JP5116935B2 - Method for evaluating the degree of canceration of a mammal-derived specimen - Google Patents

Description

  The present invention relates to a method for evaluating the degree of canceration of a mammal-derived specimen.

  Although it is becoming increasingly clear that cancer is a disease caused by genetic abnormalities, the mortality rate of cancer patients is still high, and the evaluation of currently available diagnostic methods and treatment methods etc. is not always satisfactory It is not. One of the causes may be diversity based on the type of cancer tissue, low accuracy of a gene serving as a marker, low detection sensitivity, and the like.

"Cancer as a genetic disease" (ISBN4-89553-447-2 C3047), edited by Toshio Kuroki and Tadao Kakizoe, published by Medical View Inc. (May 10, 1994)

  Therefore, development of a method for evaluating the degree of canceration of a mammal-derived specimen based on detection of a genetic abnormality, which is suitable for evaluation of diagnostic methods and treatment methods for early detection of cancer, is eagerly desired.

As a result of intensive studies under these circumstances, the present inventors have described p53-responsive gene 2 gene (PXN gene, MG50 gene, PRG2 gene, D2S448E gene, or KIAA0230 gene in cancer cell lines and cancer tissue samples. However, the expression level of the p53-responsive gene 2 gene is immortal in cancer cell lines, and is significantly methylated compared to immortalized normal cell lines and normal tissue specimens. And found that the expression level of such genes can be increased by allowing a DNA methylation inhibitor to act on a cancer cell line, leading to the present invention. .
That is, the present invention
1. A method for evaluating the degree of canceration of a mammal-derived specimen,
(1) a first step of measuring the methylation frequency of p53-responsive gene 2 gene contained in a mammal-derived specimen or an index value correlated therewith; and (2) the measured methylation frequency or correlation thereto. An evaluation method comprising the second step of determining the degree of canceration of the specimen based on a difference obtained by comparing a related index value with a control (hereinafter referred to as the evaluation method of the present invention) There is also
2. 2. The evaluation method according to item 1 above, wherein the mammal-derived specimen is a cell;
3. 2. The evaluation method according to item 1 above, wherein the mammal-derived specimen is a tissue;
4). A method for evaluating the degree of canceration of a mammal-derived specimen,
(1) First step of measuring the methylation frequency of p53-responsive gene 2 gene contained in a mammal-derived specimen, and (2) obtained by comparing the measured methylation frequency with a control. An evaluation method comprising a second step of determining the degree of canceration of the specimen based on the difference;
5. 2. The evaluation method according to item 1 above, wherein the mammal-derived specimen is a cell, and the canceration degree of the specimen is a malignancy of a mammal-derived cell;
6). The evaluation method according to item 4 above, wherein the mammal-derived specimen is a cell, and the canceration degree of the specimen is a malignancy of a mammal-derived cell;
7). 2. The evaluation method according to item 1 above, wherein the mammal-derived specimen is a tissue, and the cancerous degree of the specimen is an abundance of cancer cells in the mammal-derived tissue;
8). 5. The evaluation method according to item 4 above, wherein the mammal-derived specimen is a tissue, and the cancerous degree of the specimen is an abundance of cancer cells in the mammal-derived tissue;
9. 9. The evaluation method according to item 8 above, wherein the tissue is pancreatic tissue and the cancer is pancreatic cancer;
10. The methylation frequency of a cytosine in the nucleotide sequence represented by one or more 5'-CG-3 'existing in the nucleotide sequence in the promoter region, untranslated region or translated region of the gene The evaluation method according to item 1 or 4 above, wherein
11. 11. The evaluation method according to item 10 above, wherein the tissue is pancreatic tissue and the cancer is pancreatic cancer;
12 The methylation frequency of a gene is the methylation frequency of cytosine in the base sequence represented by one or more 5′-CG-3 ′ present in the base sequence in the promoter region of the gene The evaluation method according to 1 or 4 above;
13. The methylation frequency of a gene is the methylation frequency of cytosine in the base sequence represented by one or more 5′-CG-3 ′ present in the base sequence in the untranslated region or translated region of the gene. The evaluation method according to 1 or 4 above, characterized in that:
14 The methylation frequency of the gene is the methylation frequency of cytosine in the base sequence represented by one or more 5′-CG-3 ′ present in the base sequence represented by SEQ ID NO: 1. The evaluation method according to 1,
15. 15. The evaluation method according to item 14 above, wherein the tissue is pancreatic tissue and the cancer is pancreatic cancer;
16. A method for evaluating the degree of canceration of a mammal-derived specimen,
(1) a first step of measuring an index value correlated with the methylation frequency of the p53-responsive gene 2 gene contained in a mammal-derived specimen, and (2) a correlation between the measured methylation frequency An evaluation method comprising a second step of determining the degree of canceration of the specimen based on a difference obtained by comparing a certain index value with a control;
17. The evaluation method according to item 16 above, wherein the index value correlated with the methylation frequency of the p53-responsive gene 2 gene is the amount of the expression product of the p53-responsive gene 2 gene;
18. 18. The evaluation method according to item 17 above, wherein the amount of the expression product of the p53-responsive gene 2 gene is the amount of the transcription product of the gene;
19. 18. The evaluation method according to item 17 above, wherein the amount of the expression product of the p53-responsive gene 2 gene is the amount of the translation product of the gene;
20. A method for searching for a substance having the ability to promote the expression of p53-responsive gene 2 gene,
(1) a first step of bringing a test substance into contact with a cancer cell;
(2) After the first step (1), a second step of measuring the expression product amount of the p53-responsive gene 2 gene contained in the cancer cell,
(3) A third step of determining the ability of the test substance to promote the expression of the p53-responsive gene 2 gene based on the difference obtained by comparing the amount of the measured expression product with the control. (Hereinafter, also referred to as the present invention search method);
21. 21. The searching method according to item 20 above, wherein the cancer cell is a pancreatic cancer cell;
22. An anticancer agent comprising a substance having the ability found by the search method of the preceding item 20 as an active ingredient, wherein the active ingredient is formulated in a pharmaceutically acceptable carrier:
23. An anticancer agent comprising a nucleic acid comprising a base sequence encoding the amino acid sequence of p53-responsive gene 2 as an active ingredient, wherein the active ingredient is formulated in a pharmaceutically acceptable carrier;
24. Use of methylated p53-responsive gene 2 gene as a cancer marker;
25. 25. The use according to item 24 above, wherein the cancer marker is a pancreatic cancer marker;
26. A method of inhibiting canceration, comprising a step of administering a substance that decreases the methylation frequency of the p53-responsive gene 2 gene to cells in a mammal that can be diagnosed as having cancer;
27. 27. The method for inhibiting canceration according to 26 above, wherein the cancer is pancreatic cancer;
Etc. are provided.

  According to the present invention, a method for evaluating the degree of canceration of a mammal-derived specimen can be provided.

The present invention is described in detail below.
The present invention may be described as a methylated p53-responsive gene 2 gene (hereinafter referred to as PXN gene, MG50 gene, PRG2 gene, D2S448E gene, or KIAA0230 gene) as a cancer marker (eg, pancreatic cancer marker etc.). It is an invention related to the use etc.).
Examples of the p53-responsive gene 2 gene used as a marker gene in the present invention include, for example, an untranslated region and a translated region (coding region) containing a base sequence encoding the amino acid sequence of the human-derived p53-responsive gene 2 gene, Examples thereof include a gene containing a promoter region located 5 ′ upstream. The amino acid sequence of the human-derived p53-responsive gene 2 gene and the base sequence encoding it are described in, for example, Genbank Accession No. XM_056455. In addition, among the untranslated region and the translated region (coding region) containing the base sequence encoding the amino acid sequence of the human-derived p53-responsive gene 2 gene, the exon located on the most 5 ′ upstream side (hereinafter referred to as exon 1). )) And a promoter region located 5 ′ upstream thereof are described in, for example, Genbank Accession No. AC009471. In the base sequence described in Genbank Accession No. AC009471, for example, the base sequence of exon 1 of human-derived p53-responsive gene 2 protein is represented by base numbers 114193 to 114443. The p53-responsive gene 2 gene used in the present invention naturally occurs in addition to the gene having the above-mentioned known base sequence, such a base sequence due to species differences of individuals, individual differences or differences between organs and tissues, etc. A gene having a base sequence in which deletion, substitution or addition of a base due to mutation has occurred is also included.

  In mammals, there is a phenomenon in which only cytosine is methylated out of four types of bases constituting a gene (genomic DNA). For example, in the p53-responsive gene 2 gene derived from a mammal, a part of cytosine in the genomic DNA of the gene is methylated. The DNA methylation modification is performed in a base sequence represented by 5′-CG-3 ′ (C represents cytosine and G represents guanine. Hereinafter, the base sequence may be referred to as CpG). Limited to cytosine. The site that is methylated in cytosine is at position 5. During DNA replication prior to cell division, only cytosine in CpG of the template strand is methylated immediately after replication, but cytosine in CpG of the nascent strand is also methylated immediately by the action of methyltransferase. . Therefore, the DNA methylation state is inherited as it is by two new sets of DNA even after DNA replication.

In the first step of the evaluation method of the present invention, “methylation frequency” means, for example, that cytosine is methylated when the presence or absence of cytosine methylation in CpG to be investigated is examined for a plurality of haploids Expressed as a percentage of haploid.
In the first step of the evaluation method of the present invention, the “index value correlated with (methylation frequency)” means, for example, the amount of the expression product of the p53-responsive gene 2 gene (more specifically, the gene The amount of the transcription product, the amount of the translation product of the gene), and the like. In the case of the amount of such an expression product, there is a negative correlation that decreases as the methylation frequency increases.

The mammal-derived specimen in the first step of the evaluation method of the present invention may include, for example, cancer cells such as pancreatic cancer cells or tissues containing the same, and DNA derived from cancer cells such as pancreatic cancer cells. A cell, a tissue containing it (the tissue here has a broad meaning including blood, plasma, serum, lymph fluid, pancreatic fluid and other body fluids, lymph nodes, etc.) or body secretion (urine, milk, etc.) ) And the like. Specifically, for example, when the cancer is pancreatic cancer, pancreatic tissue (including pancreatic juice) collected from the subject animal can be exemplified.
These biological samples may be used as they are as specimens, or biological samples prepared by various operations such as separation, fractionation, and immobilization from such biological samples may be used as specimens.
When the mammal-derived specimen is blood, it can be expected that the evaluation method of the present invention will be used in periodic health examinations and simple tests.

  In the first step of the evaluation method of the present invention, a method for measuring the methylation frequency of the p53-responsive gene 2 gene contained in a mammal-derived specimen or an index value correlated therewith can be performed, for example, as follows. Good.

As a first method, DNA is first extracted from a mammal-derived specimen using, for example, a commercially available DNA extraction kit.
Incidentally, when blood is used as a specimen, plasma or serum is prepared from blood according to a normal method, and free DNA contained in the prepared plasma or serum as a specimen (cancer cells such as pancreatic cancer cells) Analysis of cancer cells such as pancreatic cancer cells, avoiding blood cell-derived DNA, and detecting cancer cells such as pancreatic cancer cells and tissues containing them Sensitivity can be improved.
Subsequently, the extracted DNA is brought into contact with a reagent that modifies unmethylated cytosine, and then is present in the base sequence of the promoter region, untranslated region or translated region (coding region) of the p53-responsive gene 2 gene. DNA containing cytosine in the base sequence represented by two or more CpGs is amplified by a polymerase chain reaction (hereinafter referred to as PCR) using a primer capable of discriminating the presence or absence of cytosine methylation to be analyzed, and Examine the amount of amplification product obtained.
Here, the base sequence represented by one or more CpGs present in the base sequence of the promoter region, untranslated region or translated region (coding region) of the p53-responsive gene 2 gene is a human-derived p53-responsive gene. The base sequence of genomic DNA containing exon 1 of 2 genes and the promoter region located 5 ′ upstream thereof can be mentioned. More specifically, the base sequence represented by SEQ ID NO: 1 (Genbank Accession No. This corresponds to a complementary sequence of the base sequence represented by base numbers 113501 to 116000 of the base sequence described in AC009471. In the base sequence represented by SEQ ID NO: 1, the base sequence of exon 1 of the human-derived p53-responsive gene 2 gene is represented by base numbers 1558 to 1808. Cytosine in the base sequence represented by CpG present in the base sequence represented by SEQ ID NO: 1 exhibits high methylation frequency (ie, hypermethylation) in cancer cells such as pancreatic cancer cells. . More specifically, as cytosine having high methylation frequency in pancreatic cancer cells, for example, in the base sequence represented by SEQ ID NO: 1, base numbers 1282, 1284, 1301, 1308, 1315, 1319, 1349, 1351, 1357 , 1361, 1365, 1378, 1383, etc. can be mentioned cytosine.

  As a reagent for modifying unmethylated cytosine, for example, bisulfite such as sodium bisulfite can be used. Incidentally, in principle, a reagent that specifically modifies only methylated cytosine may be used.

In order to bring the extracted DNA into contact with a reagent that modifies unmethylated cytosine, for example, the DNA is first denatured with an alkaline solution (pH 9-14), and then bisulfite (bisulfite) such as sodium hydrogen sulfite (solution Medium concentration: For example, the final concentration is 3 M) and the like, and the treatment is performed at 55 ° C. for about 10 to 16 hours (overnight). To accelerate the reaction, denaturation at 95 ° C and reaction at 50 ° C can be repeated 10-20 times. In this case, unmethylated cytosine is converted to uracil, while methylated cytosine is not converted to uracil and remains cytosine.
Next, when DNA treated with bisulfite or the like is used as a template and methylated cytosine is included, the base sequence [cytosine at the methylated position (cytosine in CpG) remains cytosine, PCR using a pair of methylation-specific primers each selected from a non-methylated cytosine (a cytosine not included in CpG is a uracil base sequence) and a base sequence complementary to the base sequence , And may also be referred to as methylation-specific PCR.) And nucleotide sequences when DNA treated with bisulfite or the like is used as a template and cytosine is not methylated (all cytosines became uracil) PCR using a pair of unmethylated specific primers each selected from a base sequence) and a base sequence complementary to such base sequence (hereinafter referred to as unmethylated specific P Sometimes also referred to as R.) And perform.
In the above PCR, in the case of PCR using methylation specific primers (the former), DNA in which cytosine to be analyzed is methylated is amplified, while in the case of PCR using unmethylation specific primers ( In the latter case, DNA in which cytosine to be analyzed is not methylated is amplified. By comparing the amounts of these amplified products, the presence or absence of methylation of the target cytosine is examined. In this way, the methylation frequency can be measured.

  Here, the methylation-specific primer is a cytosine that has undergone methylation in consideration that cytosine that has not been methylated is converted to uracil, and that cytosine that has undergone methylation is not converted to uracil. Design PCR primers (methylation specific primers) specific to nucleotide sequences containing, and PCR primers (non-methylation specific primers) specific to nucleotide sequences containing unmethylated cytosine To do. Since the design is based on DNA strands that have been chemically converted by bisulfite treatment and are no longer complementary, based on each strand of DNA that was originally double-stranded, a methylation specific primer and Unmethylated specific primers can also be made. Such a primer is preferably designed to contain cytosine in CpG in the vicinity of the 3 ′ end of the primer in order to increase the specificity of methyl and non-methyl. Further, in order to facilitate analysis, one of the primers may be labeled.

More specifically, primers for measuring the methylation frequency of the p53-responsive gene 2 gene by methylation-specific PCR are, for example, the promoter region, untranslated region or translated region (coding region) of the p53-responsive gene 2 gene. It can be designed as described above based on a base sequence containing one or more cytosines in CpG present in the base sequence in the region). For example, cytosine in CpG present in the nucleotide sequence represented by SEQ ID NO: 1, specifically, nucleotide numbers 1282, 1284, 1301, 1308, 1315, 1319, 1349, 1351 in the nucleotide sequence represented by SEQ ID NO: 1. , 1357, 1361, 1365, 1378, 1383, etc., can be designed based on a base sequence containing one or more cytosines. Examples of such primers are shown below.
<Unmethylated specific primer>
U1: 5'-TTTTGTGTAGGTTTTAGGGTTTT-3 '(SEQ ID NO: 2)
U2: 5'-CAACCCACATAACCAAAACA-3 '(SEQ ID NO: 3)
<Methylation specific primer>
M1: 5'-TCGCGTAGGTTTTAGGGTTTC-3 '(SEQ ID NO: 4)
M2: 5'-GACCCGCATAACCAAAACG-3 '(SEQ ID NO: 5)

As a reaction solution in methylation-specific PCR, for example, 50 ng of DNA as a template, 1 μl of each primer solution of 10 pmol / μl, 4 μl of 2.5 mM dNTP, 10 × buffer (100 mM Tris-HCl pH8 .3, mix 2.5 μl of 500 mM KCl, 20 mM MgCl ₂ ) and 0.2 μl of thermostable DNA polymerase 5 U / μl, and add sterilized ultrapure water to this to make the reaction volume 25 μl. Can do. As the reaction conditions, for example, the above reaction solution is kept at 95 ° C. for 10 minutes, then at 95 ° C. for 30 seconds, then at 55 to 65 ° C. for 30 seconds, and further at 72 ° C. for 30 seconds for one cycle. The conditions for performing the heat insulation for 30 to 40 cycles are mentioned.
After performing such PCR, the amount of amplification product obtained is compared. For example, an analytical method (denaturing polyacrylamide gel electrophoresis or agarose gel that can compare the amount of each amplification product obtained by PCR using a methylation specific primer and PCR using an unmethylated specific primer. In the case of electrophoresis, the gel after electrophoresis is stained with DNA to detect the band of the amplification product, and the concentration of the detected band is compared. Here, instead of DNA staining, a pre-labeled primer can be used to compare the band concentrations using the label as an index. In addition, when quantification is required, high-precision quantification that can detect even a slight difference of about twice as much as the gene amount can be performed by monitoring PCR reaction products in real time and performing kinetic analysis. Real-time PCR, which is a possible PCR method, can also be used to compare the amount of each product. Examples of the method for performing real-time PCR include a method using a probe such as a template-dependent nucleic acid polymerase probe or a method using an intercalator such as Cyber Green. Equipment and kits for real-time PCR are already commercially available.

  Such a method is generally called methylation-specific PCR, and is a method reported by Herman et al. (Herman et al., Proc. Natl. Acad. Sci USA, 93, 9821-9826, 1996). Thus, this method utilizes the difference in chemical properties between cytosine and 5-methylcytosine.

As a second method, DNA is first extracted from a mammal-derived specimen using, for example, a commercially available DNA extraction kit.
Incidentally, when blood is used as a specimen, plasma or serum is prepared from blood according to a normal method, and free DNA contained in the prepared plasma or serum as a specimen (cancer cells such as pancreatic cancer cells) Analysis of cancer cells such as pancreatic cancer cells, avoiding blood cell-derived DNA, and detecting cancer cells such as pancreatic cancer cells and tissues containing them Sensitivity can be improved.
Subsequently, the extracted DNA is brought into contact with a reagent that modifies unmethylated cytosine, and then is present in the base sequence of the promoter region, untranslated region or translated region (coding region) of the p53-responsive gene 2 gene. Amplification by polymerase chain reaction (hereinafter referred to as PCR) using primers designed as described later based on DNA containing cytosine in the base sequence represented by two or more CpGs, and A method for directly analyzing the base sequence can also be mentioned.
Here, the base sequence represented by one or more CpGs present in the base sequence of the promoter region, untranslated region or translated region (coding region) of the p53-responsive gene 2 gene is a human-derived p53-responsive gene. The base sequence of genomic DNA containing exon 1 of 2 genes and the promoter region located 5 ′ upstream thereof can be mentioned. More specifically, the base sequence represented by SEQ ID NO: 1 (Genbank Accession No. This corresponds to a complementary sequence of the base sequence represented by base numbers 113501 to 116000 of the base sequence described in AC009471. In the base sequence represented by SEQ ID NO: 1, the base sequence of exon 1 of the human-derived p53-responsive gene 2 gene is represented by base numbers 1558 to 1808. The cytosine in the base sequence represented by CpG present in the base sequence represented by SEQ ID NO: 1, particularly the cytosine in CpG present in the region where CpG is densely present in the base sequence represented by SEQ ID NO: 1, In cancer cells such as pancreatic cancer cells, a high methylation frequency (ie, hypermethylation state) is exhibited. More specifically, as cytosine having high methylation frequency in pancreatic cancer cells, for example, in the base sequence represented by SEQ ID NO: 1, base numbers 1282, 1284, 1301, 1308, 1315, 1319, 1349, 1351, 1357 , 1361, 1365, 1378, 1383, etc. can be mentioned cytosine.

  The primer used for the PCR may be designed as a primer pair capable of amplifying DNA having a base sequence containing the cytosine based on the base sequence 5 ′ upstream and 3 ′ downstream of the cytosine to be analyzed. . The base sequence for primer design is selected so as not to contain cytosine in the CpG to be analyzed. If the base sequence selected for primer design does not contain cytosine at all, the selected base sequence and the base sequence complementary to the base sequence should be used as the base sequence of the primer. Can do. In addition, if the base sequence selected for primer design includes cytosine other than the target of analysis but the cytosine is not cytosine in CpG, the primer is designed in consideration of the conversion of these cytosines into uracil. . That is, a pair of primers each having a base sequence in which all cytosines are uracil and a base sequence complementary to the base sequence are designed. Furthermore, when the base sequence selected for primer design contains cytosine other than the analysis target and the cytosine is cytosine in CpG, cytosine that has not undergone methylation is converted to uracil, and methylation is performed. Primers are designed taking into account that the cytosine undergoing treatment is not converted to uracil. That is, the base sequence in the case where methylated cytosine is included [cytosine at the position to be methylated (cytosine in CpG) remains cytosine, and unmethylated cytosine (cytosine not included in CpG) is A base sequence in the form of uracil], a pair of methylation-specific primers each selected from a base sequence complementary to such a base sequence, and a base sequence when cytosine is not methylated (all cytosines are uracil) And a pair of unmethylated specific primers each having a base sequence complementary to the base sequence. In this case, in the above PCR, a methylation specific primer pair and an unmethylation specific primer pair are mixed in equal amounts and used.

  As a reagent for modifying unmethylated cytosine, for example, bisulfite such as sodium bisulfite can be used. Incidentally, in principle, a reagent that modifies only methylated cytosine may be used.

In order to bring the extracted DNA into contact with a reagent that modifies unmethylated cytosine, for example, first, the DNA is bisulphite (bisulfite) such as sodium bisulfite (concentration in the solution) in an alkaline solution (pH 9-14). : Treat at 55 ° C. for about 10 to 16 hours (overnight) with a final concentration of 3M, for example. To accelerate the reaction, denaturation at 95 ° C and reaction at 50 ° C can be repeated 10-20 times. In this case, unmethylated cytosine is converted to uracil, while methylated cytosine is not converted to uracil and remains cytosine.
Next, PCR is performed using DNA treated with bisulfite or the like as a template and using primers designed as described above. By comparing the base sequences of the obtained amplification products, the methylation frequency can be measured from the comparison.

More specifically, the primer for measuring the methylation frequency of the p53-responsive gene 2 gene by direct analysis of the base sequence is, for example, a promoter region, an untranslated region or a translated region of the p53-responsive gene 2 gene ( It can be designed as described above based on a base sequence containing one or more cytosines in CpG present in the base sequence in the coding region). For example, cytosine in CpG existing in the base sequence represented by SEQ ID NO: 1, specifically, base numbers 991, 999, 1004, 1023, 1042, 1097, 1114, 1122 in the base sequence represented by SEQ ID NO: 1. , 1150, 1152, 1158, 1160, 1170, 1176, 1190, 1218, 1234, 1243, 1258, 1282, 1284, 1301, 1308, 1315, 1319, etc. be able to. Examples of such primers are shown below.
Incidentally, in the base sequence represented by SEQ ID NO: 1, base numbers 991, 999, 1004, 1023, 1042, 1097, 1114, 1122, 1150, 1152, 1158, 1160, 1170, 1176, 1190, 1218, 1234, 1243, 1258 , 1282, 1284, 1301, 1308, 1315, 1319, etc., to determine the methylation frequency of cytosine, using the primer designed as described above, the bisulfite of base numbers 967 to 1342 in SEQ ID NO: 1 DNA (376 bp) corresponding to the base sequence after the treatment is amplified.
<Primer>
B1: 5'-AGAGAGTAGGTGGTTGATAG-3 '(SEQ ID NO: 6)
B2: 5'-AACATTAACACCCCTAATTCTA-3 '(SEQ ID NO: 7)

As a reaction solution in PCR, for example, 25 ng of DNA as a template, 1 μl of each primer solution of 20 pmol / μl, 3 μl of 2 mM dNTP, 10 × buffer (100 mM Tris-HCl pH 8.3, 500 mM KCl, A reaction solution in which 2.5 μl of 15 mM MgCl ₂ ) and 0.2 μl of thermostable DNA polymerase 5 U / μl are mixed, and sterilized ultrapure water is added to make the solution volume 25 μl can be mentioned. As the reaction conditions, for example, the above reaction solution is kept at 95 ° C. for 10 minutes, then at 95 ° C. for 30 seconds, then at 53 ° C. for 30 seconds, and further at 72 ° C. for 30 seconds as one cycle. A condition for performing the heat insulation for 30 to 40 cycles is mentioned.
After performing such PCR, the base sequences of the amplification products obtained are compared, and the methylation frequency is measured from the comparison.
That is, by directly analyzing the base sequence of the amplification product, it is determined whether the base at the position corresponding to the cytosine to be analyzed is cytosine or thymine (uracil). In the peak chart showing the base in the obtained amplification product, by comparing the area of the peak showing cytosine detected at the position corresponding to the cytosine to be analyzed with the area of the peak showing thymine (uracil), The frequency of cytosine methylation to be analyzed can be measured. In addition, as a method for directly analyzing the base sequence, each cloned DNA is prepared from a plurality of clones obtained by cloning the amplification product obtained by PCR once using Escherichia coli or the like as a host. The base sequence may be analyzed. The frequency of cytosine methylation to be analyzed can also be measured by obtaining the ratio of the sample whose base detected at the position corresponding to the cytosine to be analyzed in the sample to be analyzed is cytosine.

As a third method, DNA is first extracted from a mammal-derived specimen using, for example, a commercially available DNA extraction kit.
Incidentally, when blood is used as a specimen, plasma or serum is prepared from blood according to a normal method, and free DNA contained in the prepared plasma or serum as a specimen (cancer cells such as pancreatic cancer cells) Analysis of cancer cells such as pancreatic cancer cells, avoiding blood cell-derived DNA, and detecting cancer cells such as pancreatic cancer cells and tissues containing them Sensitivity can be improved.
Subsequently, the extracted DNA is brought into contact with a reagent that modifies unmethylated cytosine, and then is present in the base sequence of the promoter region, untranslated region or translated region (coding region) of the p53-responsive gene 2 gene. DNA containing cytosine in the base sequence represented by two or more CpGs is hybridized with a probe capable of discriminating the presence or absence of cytosine to be analyzed, and the presence of binding between the DNA and the probe is examined. You can also give a way.
Here, the base sequence represented by one or more CpGs present in the base sequence of the promoter region, untranslated region or translated region (coding region) of the p53-responsive gene 2 gene is a human-derived p53-responsive gene. The base sequence of genomic DNA containing exon 1 of 2 genes and the promoter region located 5 ′ upstream thereof can be mentioned. More specifically, the base sequence represented by SEQ ID NO: 1 (Genbank Accession No. This corresponds to a complementary sequence of the base sequence represented by base numbers 113501 to 116000 of the base sequence described in AC009471. In the base sequence represented by SEQ ID NO: 1, the base sequence of exon 1 of the human-derived p53-responsive gene 2 gene is represented by base numbers 1558 to 1808. The cytosine in the base sequence represented by CpG present in the base sequence represented by SEQ ID NO: 1, particularly the cytosine in CpG present in the region where CpG is densely present in the base sequence represented by SEQ ID NO: 1, In cancer cells such as pancreatic cancer cells, a high methylation frequency (ie, hypermethylation state) is exhibited. More specifically, as cytosine having high methylation frequency in pancreatic cancer cells, for example, in the base sequence represented by SEQ ID NO: 1, base numbers 1282, 1284, 1301, 1308, 1315, 1319, 1349, 1351, 1357 , 1361, 1365, 1378, 1383, etc. can be mentioned cytosine.

  The probe used for the hybridization is based on a base sequence containing cytosine to be analyzed, and cytosine that has not been methylated is converted to uracil, and methylated cytosine is not converted to uracil. It is better to design in consideration of this. That is, the base sequence in the case where methylated cytosine is included [cytosine at the position to be methylated (cytosine in CpG) remains cytosine, and unmethylated cytosine (cytosine not included in CpG) is Base sequence in which uracil is converted] or a methylation specific probe having a base sequence complementary to such a base sequence, and a base sequence in the case where cytosine is not methylated (base sequence in which all cytosines are converted into uracil) Or an unmethylated specific probe having a base sequence complementary to such a base sequence is designed. Such a probe may be used after being labeled in order to facilitate analysis of the presence or absence of binding between the DNA and the probe. In addition, the probe may be used by being immobilized on a carrier according to a usual method. In this case, DNA extracted from a mammal-derived specimen may be labeled in advance.

  As a reagent for modifying unmethylated cytosine, for example, bisulfite such as sodium bisulfite can be used. Incidentally, in principle, a reagent that specifically modifies only methylated cytosine may be used.

In order to bring the extracted DNA into contact with a reagent that modifies unmethylated cytosine, for example, the DNA is first denatured with an alkaline solution (pH 9-14), and then bisulfite (bisulfite) such as sodium hydrogen sulfite (solution Medium concentration: For example, the final concentration is 3 M) and the like, and the treatment is performed at 55 ° C. for about 10 to 16 hours (overnight). To accelerate the reaction, denaturation at 95 ° C and reaction at 50 ° C can be repeated 10-20 times. In this case, unmethylated cytosine is converted to uracil, while methylated cytosine is not converted to uracil and remains cytosine.
If necessary, the DNA may be amplified in advance by performing PCR in the same manner as in the second method using DNA treated with bisulfite or the like as a template.
Next, hybridization between DNA treated with bisulfite or the like or DNA previously amplified by PCR and a probe capable of identifying the presence or absence of methylation of cytosine to be analyzed is performed. By comparing the amount of DNA that binds to a methylation-specific probe and the amount of DNA that binds to an unmethylated-specific probe, the frequency of cytosine methylation to be analyzed can be measured.

More specifically, the probe for measuring the methylation frequency of the p53-responsive gene 2 gene is, for example, a base sequence in the promoter region, untranslated region or translated region (coding region) of the p53-responsive gene 2 gene. It can be designed as described above based on a base sequence containing one or more cytosines in CpG. For example, cytosine in CpG present in the nucleotide sequence represented by SEQ ID NO: 1, specifically, nucleotide numbers 1282, 1284, 1301, 1308, 1315, 1319, 1349, 1351 in the nucleotide sequence represented by SEQ ID NO: 1. , 1357, 1361, 1365, 1378, 1383, etc., can be designed based on a base sequence containing one or more cytosines. Examples of such probes are shown below.
<Set 1>
Unmethylated specific probe: 5'-TTGTGTAGGTTTTAGGGTTTTGAGTTTTGAGTTTTG-3 '(SEQ ID NO: 8)
Methylation specific probe: 5'-TCGCGTAGGTTTTAGGGTTTCGAGTTTCGAGTTTCG-3 '(SEQ ID NO: 9)
<Set 2>
Unmethylated specific probe: 5'-TTGTGTTTTTGAGTGTTTGTTTTGGTTATGTGGGTT-3 '(SEQ ID NO: 10)
Methylation specific probe: 5'-TCGCGTTTTCGAGCGTTCGTTTTGGTTATGCGGGTC-3 '(SEQ ID NO: 11)

Hybridization is a conventional method described in, for example, Sambrook J., Frisch EF, Maniatis T., Molecular Cloning 2nd edition, Cold Spring Harbor Laboratory press. It can be performed according to. Hybridization is usually performed under stringent conditions. Here, “under stringent conditions” means, for example, hybrid at 45 ° C. in a solution containing 6 × SSC (a solution containing 1.5M NaCl and 0.15M trisodium citrate is 10 × SSC). And the like (Molecular Biology, John Wiley & Sons, NY (1989), 6.3.1-6.3.6) and the like. The salt concentration in the washing step can be selected, for example, from 2 × SSC at 50 ° C. (low stringency conditions) to 0.2 × SSC at 50 ° C. (high stringency conditions). The temperature in the washing step can be selected, for example, from room temperature (low stringency conditions) to 65 ° C. (high stringency conditions). It is also possible to change both the salt concentration and the temperature.
After such hybridization, the amount of DNA bound to the methylation-specific probe is compared with the amount of DNA bound to the non-methylation-specific probe, so that the cytosine to be analyzed (that is, the probe) The frequency of methylation of cytosine in CpG contained in the base sequence on which the design was based can be measured.

As a fourth method, DNA is first extracted from a mammal-derived specimen using, for example, a commercially available DNA extraction kit.
Incidentally, when blood is used as a specimen, plasma or serum is prepared from blood according to a normal method, and free DNA contained in the prepared plasma or serum as a specimen (cancer cells such as pancreatic cancer cells) Analysis of cancer cells such as pancreatic cancer cells, avoiding blood cell-derived DNA, and detecting cancer cells such as pancreatic cancer cells and tissues containing them Sensitivity can be improved.
Next, after the extracted DNA is allowed to act on a restriction enzyme capable of identifying the presence or absence of methylation of cytosine to be analyzed, a method for examining the presence or absence of digestion with the restriction enzyme can also be mentioned.
Here, the base sequence represented by one or more CpGs present in the base sequence of the promoter region, untranslated region or translated region (coding region) of the p53-responsive gene 2 gene is a human-derived p53-responsive gene. The base sequence of genomic DNA containing exon 1 of 2 genes and the promoter region located 5 ′ upstream thereof can be mentioned. More specifically, the base sequence represented by SEQ ID NO: 1 (Genbank Accession No. This corresponds to a complementary sequence of the base sequence represented by base numbers 113501 to 116000 of the base sequence described in AC009471. In the base sequence represented by SEQ ID NO: 1, the base sequence of exon 1 of the human-derived p53-responsive gene 2 gene is represented by base numbers 1558 to 1808. The cytosine in the base sequence represented by CpG present in the base sequence represented by SEQ ID NO: 1, particularly the cytosine in CpG present in the region where CpG is densely present in the base sequence represented by SEQ ID NO: 1, In cancer cells such as pancreatic cancer cells, a high methylation frequency (ie, hypermethylation state) is exhibited. More specifically, as cytosine having high methylation frequency in pancreatic cancer cells, for example, in the base sequence represented by SEQ ID NO: 1, base numbers 1282, 1284, 1301, 1308, 1315, 1319, 1349, 1351, 1357 , 1361, 1365, 1378, 1383, etc. can be mentioned cytosine.

  The “restriction enzyme capable of distinguishing the presence or absence of cytosine methylation” (hereinafter sometimes referred to as a methylation-sensitive restriction enzyme) used in the method means that a recognition sequence containing methylated cytosine is not digested. Means a restriction enzyme capable of digesting a recognition sequence containing unmethylated cytosine. When the cytosine contained in the recognition sequence is methylated, the DNA is not cleaved by the action of a methylation sensitive restriction enzyme, whereas the cytosine contained in the recognition sequence is not methylated When the methylation sensitive restriction enzyme is allowed to act, the DNA is cleaved. Specific examples of the methylation-sensitive enzyme include HpaII, BstUI, NarI, SacII and the like.

As a method for examining the presence or absence of digestion with the restriction enzyme, for example, the DNA is used as a template, the cytosine to be analyzed is included in the recognition sequence, and the DNA that does not contain the restriction enzyme recognition sequence other than the recognition sequence is amplified. There can be mentioned a method in which PCR is performed using possible primer pairs and the presence or absence of DNA amplification (amplification product) is examined. When cytosine to be analyzed is methylated, an amplification product is obtained. On the other hand, when the cytosine to be analyzed is not methylated, an amplification product cannot be obtained. Thus, by comparing the amounts of amplified DNA, the frequency of cytosine methylation to be analyzed can be measured. When quantification is required, high-accuracy quantification is possible by detecting PCR reaction products in real time and performing kinetic analysis, for example, to detect even a slight difference of about twice the gene amount. The amount of each product can also be compared using real-time PCR, which is a PCR method. Examples of the method for performing real-time PCR include a method using a probe such as a template-dependent nucleic acid polymerase probe or a method using an intercalator such as Cyber Green. Equipment and kits for real-time PCR are already commercially available.
For example, in the case of cytosine represented by base numbers 1218, 1498, 1636, and 1790 in the base sequence represented by SEQ ID NO: 1, the cytosine is included in the recognition sequence of NarI, and the cytosine is methylated by the above method. The frequency can be measured.

  In addition, as another method for examining the presence or absence of digestion with the restriction enzyme, for example, the p53-responsive gene 2 gene is converted to DNA subjected to the action of a methylation sensitive restriction enzyme containing cytosine to be analyzed in the recognition sequence. A method of examining the length of the hybridized DNA by carrying out Southern hybridization using a DNA derived from and not containing the restriction enzyme recognition sequence as a probe can also be mentioned. When the cytosine to be analyzed is methylated, longer DNA is detected than when the cytosine is not methylated. By comparing the amount of detected long DNA and the amount of short DNA, the frequency of cytosine methylation to be analyzed can be measured.

Using the various methods as described above, the methylation frequency of the p53-responsive gene 2 gene contained in a mammal-derived specimen is measured. Compare the measured methylation frequency with the methylation frequency (control) of the p53-responsive gene 2 gene contained in a sample derived from a healthy mammal that can be diagnosed as having no cancer cells such as pancreatic cancer cells. Then, the canceration degree of the specimen is determined based on the difference obtained by the comparison. If the methylation frequency of the p53-responsive gene 2 gene contained in the mammal-derived sample is higher than that of the control (if the p53-responsive gene 2 gene is hypermethylated compared to the control) It can be determined that the degree of canceration of the specimen is high in comparison with the control.
Here, the “degree of canceration” is generally the same as the meaning used in this field, and specifically, for example, when the mammal-derived specimen is a cell, it means the malignancy of the cell. For example, when the mammal-derived specimen is a tissue, it means the abundance of cancer cells in the tissue.

The expression of the p53-responsive gene 2 gene is lower in cancer cells such as pancreatic cancer cells than in specimens such as cells and tissues derived from healthy mammals. This is because the gene methylation frequency is high in cancer cells such as pancreatic cancer cells, and the gene cannot be normally expressed. As a result, the amount of the expression product of the gene (more specifically, the transcription product The amount of translation products). As described above, in the evaluation method of the present invention and the like, instead of the methylation frequency, there is an index value correlated therewith (in the above case, the index value is an amount of the expression product and has a negative correlation). ) May be measured.
That is, in the evaluation method of the present invention, an index value (for example, the amount of the expression product) correlated with the methylation frequency of the p53-responsive gene 2 gene contained in the mammal-derived specimen is measured, and the measured methyl The degree of canceration of the specimen can be determined on the basis of a difference obtained by comparing an index value (for example, the amount of an expression product) having a correlation with the conversion frequency and a control.

In the first step of the evaluation method of the present invention, as a method for measuring an index value correlated with the methylation frequency of the p53-responsive gene 2 gene contained in the mammal-derived specimen, for example, the p53-responsive gene 2 gene A method for measuring the amount of mRNA that is the transcription product of can be mentioned. For the measurement, for example, RT-PCR method, Northern blot method [Molecular Cloning, Cold Spring Harbor Laboratory (1989)], in situ RT-PCR method [Nucleic Acids Res., 21, 3159-3166 (1993)], in A known method such as in situ hybridization method or NASBA method [Nucleic acid sequence-based amplification, nature, 350, 91-92 (1991)] may be used.
A sample containing mRNA which is a transcription product of p53-responsive gene 2 gene contained in a mammal-derived specimen may be prepared by extraction, purification, etc. from the specimen according to a normal method.
When Northern blotting is used to measure the amount of mRNA contained in the prepared sample, the detection probe is the p53-responsive gene 2 gene or a part thereof (restriction enzyme cleavage of the p53-responsive gene 2 gene). , About 100 bp to about 1000 bp oligonucleotide etc. chemically synthesized according to the base sequence of p53-responsive gene 2 gene) and the detection conditions used in hybridization with mRNA contained in the sample There is no particular limitation as long as it gives a detectable specificity.
If RT-PCR is used to measure the amount of mRNA contained in the prepared sample, the primer used should be one that can specifically amplify only the p53-responsive gene 2 gene. The region to be amplified and the base length are not particularly limited. Examples of such primers include the following primers (S: sense, A: antisense). Using these primers, the amount of the transcription product by RT-PCR method can also be measured as shown in the Examples below. When quantification is required, high-accuracy quantification is possible by detecting PCR reaction products in real time and performing kinetic analysis, for example, to detect even a slight difference of about twice the gene amount. The amount of each product can also be compared using real-time PCR, which is a PCR method. Examples of the method for performing real-time PCR include a method using a probe such as a template-dependent nucleic acid polymerase probe or a method using an intercalator such as Cyber Green. Equipment and kits for real-time PCR are already commercially available.
S: 5'-GCCGCAGACCTCCATCC-3 '(SEQ ID NO: 12)
A: 5'-GCAATGTGTTCAAGTTCCTCAGC-3 '(SEQ ID NO: 13)

In the first step of the evaluation method of the present invention, as another method for measuring an index value correlated with the methylation frequency of the p53-responsive gene 2 gene contained in a mammal-derived specimen, for example, p53-responsive A method for measuring the amount of p53-responsive gene 2 protein, which is the translation product of gene 2, can be mentioned. For the measurement, for example, an immunoblot method described in Cell Engineering Handbook, Yodosha, 207 (1992) using a specific antibody (monoclonal antibody, polyclonal antibody) against p53-responsive gene 2 protein, A known method such as a separation method by immunoprecipitation or an indirect competitive inhibition method (ELISA method) may be used.
Incidentally, a specific antibody against the p53-responsive gene 2 protein can be produced according to an ordinary immunological method using the protein as an immunizing antigen.

  Using the various methods as described above, an index value correlated with the methylation frequency of the p53-responsive gene 2 gene contained in the mammal-derived specimen is measured. Index value correlated with the measured methylation frequency and methylation of p53-responsive gene 2 gene contained in specimens derived from healthy mammals that can be diagnosed as having no cancer cells such as pancreatic cancer cells, for example An index value (control) having a correlation in frequency is compared, and the degree of canceration of the specimen is determined based on a difference obtained by the comparison. For example, if the index value that is positively correlated with the methylation frequency of the p53-responsive gene 2 gene contained in the mammal-derived specimen is higher than that of the control, the index value that is negatively correlated is compared with the control. If it is low (if the p53-responsive gene 2 gene is hypermethylated in comparison with the control), it can be determined that the degree of canceration of the sample is high in comparison with the control.

  The primer, probe or specific antibody that can be used in various methods for measuring the methylation frequency of p53-responsive gene 2 gene or an index value correlated therewith in the evaluation method of the present invention is used for cancers such as pancreatic cancer cells. It is useful as a reagent for a cell detection kit. The present invention relates to a kit for detecting cancer cells such as pancreatic cancer cells containing these primers, probes or specific antibodies as a reagent, or a pancreas in which these primers, probes or specific antibodies are immobilized on a carrier. A chip for detecting cancer cells such as cancer cells is also provided, and the scope of rights of the evaluation method of the present invention is such as the detection kit and the detection chip as described above using the substantial principle of the method. Of course, use in various forms is also included.

The expression of the p53-responsive gene 2 gene is lower in cancer cells such as pancreatic cancer cells than in specimens such as cells and tissues derived from healthy mammals. On the other hand, as shown in Examples described later, by causing a substance that inhibits DNA methylation related to the p53-responsive gene 2 gene to act on cancer cells such as pancreatic cancer cells, the amount of the expression product of the gene is increased. be able to. This is a substance that can compensate for the decreased expression level of the p53-responsive gene 2 gene in cancer cells such as pancreatic cancer cells or the associated functional decrease—for example, unmethylated (or methylated as found in cancer) P53-responsive gene 2 gene, which is not abnormal), an expression product of the gene, a substance capable of promoting the expression of the gene (for example, a substance that inhibits DNA methylation of the p53-responsive gene 2 gene, p53 -responsive gene 2 is a substance that reduces the methylation frequency of gene 2)-and the like means that it is useful for the treatment of cancer such as pancreatic cancer and the suppression of canceration of normal tissues such as pancreas.
For example, administration of a substance that decreases the methylation frequency of the p53-responsive gene 2 gene to cells in the body of a mammal that can be diagnosed as cancer will suppress canceration. Also, for example, by providing a substance that inhibits DNA methylation related to the p53-responsive gene 2 gene to cancer cells such as pancreatic cancer cells, the nucleotide sequence in the promoter region or coding region of the p53-responsive gene 2 gene The cytosine in the existing CpG is hypomethylated in the same way as in normal tissues, increasing the expression level of mRNA, which is the transcription product of the p53-responsive gene 2 gene, and consequently the translation product of the p53-responsive gene 2 gene. It would be possible to increase the expression level of the p53-responsive gene 2 protein. In addition, for example, p53-responsive gene 2 gene or p53-responsive gene 2 protein is introduced into a cancer cell such as pancreatic cancer cell by introducing a cDNA comprising a base sequence encoding the amino acid sequence of p53-responsive gene 2 protein into p53 in cancer cells such as pancreatic cancer cells. -Responsive gene 2 protein expression could be increased.

  That is, in the present invention, (1) the active ingredient contains a substance having the ability to promote the expression of the p53-responsive gene 2 gene, and the active ingredient is formulated in a pharmaceutically acceptable carrier. And (2) a nucleic acid comprising a base sequence encoding the amino acid sequence of the p53-responsive gene 2 gene as an active ingredient, and the active ingredient is formulated in a pharmaceutically acceptable carrier Are also provided (hereinafter, collectively referred to as the anticancer agent of the present invention).

The dosage form of the anticancer agent of the present invention is not particularly limited as long as it is a normal formulation, but such a formulation is pharmaceutically acceptable, for example, a water-soluble solvent, a water-insoluble solvent, a buffering agent, a solubilizing agent. It can be produced by blending an active ingredient in a carrier such as an isotonic agent and a stabilizer. You may add adjuvants, such as antiseptic | preservative, a suspending agent, and an emulsifier, as needed. Moreover, when administering parenterally (in general, injection etc. are preferable), the said anticancer agent can be used with the form of normal liquid agents, such as a solution.
An effective amount of the anticancer agent of the present invention can be administered parenterally to a mammal such as a human (for example, cells in the body of a mammal that can be diagnosed as having cancer). For example, parenteral administration methods include injection (subcutaneous, intravenous, topical) and the like.
The dosage varies depending on the age, sex, weight, disease level, type of the anticancer drug of the present invention, dosage form, etc. of the mammal to be administered, but usually the active ingredient is effective in the patient cell. The amount of the active ingredient that produces an intracellular level equal to the appropriate concentration level may be administered. In addition, the above-mentioned daily dose can be administered once or divided into several times.

Here, as a method for introducing the p53-responsive gene 2 gene into a cell, a gene introduction method using a viral vector or a gene introduction method using a non-viral vector (Nikkei Science, April 1994, 20-45). Page, Experimental medicine special edition, 12 (15) (1994), Experimental medicine separate volume "Basic technology of gene therapy", Yodosha (1996)).
As the former gene transfer method, for example, a TR4 or mutant TR4 is encoded on a DNA virus or RNA virus such as a retrovirus, adenovirus, adeno-associated virus, herpes virus, vaccinia virus, poxvirus, poliovirus, symbisvirus, etc. For example, a method of introducing and incorporating DNA to be performed is included. Examples of gene introduction methods using non-viral vectors include a method in which an expression plasmid is directly administered into muscle (DNA vaccine method), a liposome method, a lipofectin method, a microinjection method, a calcium phosphate method, an electroporation method, and the like. Can be given.
In addition, as a method of using DNA of p53-responsive gene 2 gene as an active ingredient of a gene therapy agent as an anticancer agent, an in vivo method in which DNA of the gene is directly introduced into the body, a specific cell is removed from a human body Ex vivo method of introducing DNA of the gene into the cell and returning the cell to the body (Nikkei Science, April 1994, pages 20-45, Monthly Pharmaceutical Affairs, 36 (1), 23-48 (1994), Experimental medicine special edition, 12 (15) (1994)).
In the former in vivo method, the DNA of the gene can be administered by an appropriate administration route according to the disease, symptoms and the like. For example, it can be administered by injection into pancreatic cancer cells, veins, arteries, subcutaneous, intradermal, intramuscular or the like.
As a dosage form of the gene therapy agent as the anticancer agent, it can also be a liposome preparation such as an injection, a suspension, a freezing agent, and a centrifugal concentrated freezing agent. Such a preparation is pharmaceutically acceptable, for example, the gene (vector type or virus type, or the like) in a carrier such as a water-soluble solvent, a water-insoluble solvent, a buffer, a solubilizing agent, an isotonic agent, and a stabilizer. Or a plasmid type of the above gene form). You may add adjuvants, such as antiseptic | preservative, a suspending agent, and an emulsifier, as needed. Moreover, when administering parenterally (in general, injection etc. are preferable), the said anticancer agent can be used with the form of normal liquid agents, such as a solution.

The search method of the present invention is a search method for a substance having the ability to promote the expression of the p53-responsive gene 2 gene, wherein (1) a first step of contacting a test substance with a cancer cell, (2) a first step ( 1) Later, based on the difference obtained by comparing the amount of the measured expression product with the control, the second step of measuring the expression product amount of the p53-responsive gene 2 gene contained in the cancer cell A third step of determining the ability of the test substance to promote the expression of the p53-responsive gene 2 gene;
The cancer cell in the first step of the search method of the present invention is not particularly limited, and may be a cancer cell isolated from a mammal-derived cancer tissue, or a mammal-derived cancer established as a cell line. It may be a cell line. Examples of the mammal include humans, monkeys, mice, rats, hamsters and the like. Preferred types of cancer include pancreatic cancer and the like. Specifically, for example, known human-derived pancreatic cancer cell lines such as BXPc3, HPAF-II, Capan-2, MiaPaCa-2, Hs766T, PANC-1 and HPAC (all available from ATCC) can be mentioned. it can.
The amount of cancer cells for bringing the test substance into contact with the cancer cells in the first step of the search method of the present invention is usually about 10 ⁴ to 10 ⁸ cells, preferably about 10 ⁵ to 10 ⁷ cells. The concentration of the test substance is usually about 0.1 ng / ml to about 100 μg / ml, preferably about 1 ng / ml to about 50 μg / ml. The time for contacting the test substance with the cancer cells is usually about 1 hour to 5 days, preferably about several hours to 2 days. The number of times that the test substance is brought into contact with the cancer cell may be one time or a plurality of times.
The environment in which the test substance is brought into contact with the cancer cell is preferably an environment in which the vital activity of the cancer cell is maintained. For example, an environment in which the energy source of the cancer cell coexists can be given. Specifically, it is convenient that the first step is performed in a medium.
In order to measure the amount of the expression product of p53-responsive gene 2 gene contained in cancer cells in the second step of the search method of the present invention, the above-mentioned “in the first step of the evaluation method of the present invention, a sample derived from a mammal is used. The measurement may be performed according to “Method for Measuring Index Value Correlated to Methylation Frequency of Included p53-responsive Gene 2 Gene”.
To determine the ability of the test substance to promote the expression of the p53-responsive gene 2 gene based on the difference obtained by comparing the amount of expression product measured in the second step of the search method of the present invention with a control As described above, when the measured expression product amount and, for example, the concentration of the test substance for bringing the test substance into contact with the cancer cell in the first step of the search method of the present invention is zero (ie, the cancer cell Expression of the p53-responsive gene 2 gene (control) when the test substance is not in contact) and the expression of the p53-responsive gene 2 gene in the test substance based on the difference obtained by the comparison Determine the ability to promote. If the amount of expression product of the p53-responsive gene 2 gene contained in the cancer cell contacted with the test substance is the control (in this case, the amount of the p53-responsive gene 2 gene contained in the cancer cell not contacted with the test substance). If it is higher than the expression product amount), it can be determined that the test substance has the ability to promote the expression of the p53-responsive gene 2 gene. Of course, as a control, the amount of the expression product of the p53-responsive gene 2 gene when another test substance is brought into contact with the cancer cell may be used, and in this case, the p53-responsive gene that the other test substance has in advance. It is preferable that the ability to promote the expression of two genes is known.
In this way, it is possible to search for substances having the ability to promote the expression of the p53-responsive gene 2 gene. As a background or control, the p53-responsive gene 2 gene contained in a normal cell line such as a normal gastric cell line or a healthy mammal that can be diagnosed as having no cancer cells such as pancreatic cancer cells. It is preferable to measure the amount of the expression product both when the test substance is contacted and when it is not contacted.

  EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 (Confirmation test of p53-responsive gene 2 gene methylation status in pancreatic cancer cell line)
7 human pancreatic cancer cell lines [BXPc3, HPAF-II, Capan-2, MiaPaCa-2, Hs766T, PANC-1 and HPAC (all manufactured by ATCC)] are described in the catalog of ATCC (American Type Culture Collection) After culturing in a dedicated medium for each cell line until subconfluent, about 1 × 10 ⁷ cells were collected. Two immortalized (normal) pancreatic ductal epithelial cell lines (HPDE-4 / E6E7 and HPDE6-E6E7c7) obtained by a general immortalization method [Am. J. Pathol., 148,1763-1770 (1996)] [These are preserved and managed by Dr. Tsao (Ontario Cancer Institute and Department of Pathology, Unversity of Toronto) and can be transferred from the investigator]. The final concentration of 50 U / mL penicillin and After culturing until Keratinocyte-SFM, liquid (manufactured by Invitrogen) supplemented with 50 ug / mL streptomycin as a medium until subconfluent, about 1 × 10 ⁷ cells were collected. A 10-fold volume of SEDTA buffer [10 mM Tris-HCl (pH 8.0), 10 mM EDTA (pH 8.0), 100 mM NaCl]] was added to the collected cells, and this was homogenized. After adding proteinase K (Sigma) to 500 μg / ml and sodium dodecyl sulfate to 1% (w / v) to the obtained mixture, it was shaken at 55 ° C. for about 16 hours. After completion of the shaking, the mixture was extracted with phenol [saturated with 1M Tris-HCl (pH 8.0)] and chloroform. The aqueous layer was recovered, and NaCl was added to this to 0.5 N, followed by ethanol precipitation to recover the precipitate. The recovered precipitate was dissolved in TE buffer (10 mM Tris, 1 mM EDTA, pH 8.0), and RNase A (Sigma) was added to this so as to be 40 μg / ml, followed by incubation at 37 ° C. for 1 hour. The incubated mixture was extracted with phenol / chloroform. The aqueous layer was collected, and NaCl was added to this to 0.5 N, followed by ethanol precipitation to collect the precipitate (genomic DNA). The collected precipitate was rinsed with 70% ethanol to obtain genomic DNA.
The obtained genomic DNA was digested with the restriction enzyme BamHI, and then Clark et al., Nucl. Acids. Res., 22, 2990-2997, 1994; Herman et al., Pro. Natl. Acad. Sci. USA, 93, 9821-9826, 1996 The sodium bisulfite treatment was performed according to the method described in 1996. That is, restriction enzyme-treated genomic DNA (about 500 ng) was dissolved in distilled water to prepare 20 μl of genomic DNA solution. After adding about 1 μl of 6M sodium hydroxide (final concentration: about 0.3M), The mixture was incubated at 37 ° C. for 15 minutes. To this mixture, 0.6 mM hydroquinone (Sigma) was added to a final concentration of 0.5 mM, and sodium bisulfite (Sigma) was added to a final concentration of 3.1 M. Then, this was added at 95 ° C. for 30 seconds and at 50 ° C. for 15 minutes for one cycle. Insulation was performed for 15 cycles. DNA was purified from the incubated solution using Wizard DNA clean-up system (Promega). The purified DNA was dissolved in 50 μl of TE buffer, and sodium hydroxide was added to this to a final concentration of 0.3 M, and then the mixture was allowed to stand at room temperature for 5 minutes. Subsequently, precipitation (DNA) was collect | recovered by carrying out ethanol precipitation of the left-over mixture. The collected precipitate was suspended in 20 μl of TE buffer.

Using the obtained DNA as a template, PCR was performed using unmethylated specific primers U1 and U2 shown below or methylated specific primers M1 and M2. When the unmethylated specific primers U1 and U2 are used, 106 bp DNA corresponding to the base sequence after the bisulfite treatment of base numbers 1279 to 1384 of the base sequence shown in SEQ ID NO: 1 is amplified, When methylation-specific primers M1 and M2 are used, 103 bp DNA corresponding to the base sequence after the bisulfite treatment of base numbers 1281 to 1383 shown in SEQ ID NO: 1 is amplified.
<Unmethylated specific primer>
U1: 5'-TTTTGTGTAGGTTTTAGGGTTTT-3 '(SEQ ID NO: 2)
U2: 5'-CAACCCACATAACCAAAACA-3 '(SEQ ID NO: 3)
<Methylation specific primer>
M1: 5'-TCGCGTAGGTTTTAGGGTTTC-3 '(SEQ ID NO: 4)
M2: 5'-GACCCGCATAACCAAAACG-3 '(SEQ ID NO: 5)
In order to confirm the specificity of the methylation-specific primer and the non-methylation-specific primer, first, genomic DNA (from an immortalized (normal) pancreatic duct epithelial cell line (HPDE-4 / E6E7) by a conventional method ( 1) was extracted, and a part of this was treated with methylase SssI (NEB) to methylate all 5′-CG-3 ′ of genomic DNA (2). These (1) and (2) were also subjected to methylation-specific PCR and unmethylation-specific PCR.

As a PCR reaction solution, 25 ng of DNA as a template, 1 μl of the above primer solution of 20 pmol / μl, 2.5 μl of each 2 mM dNTP, 10 × buffer (100 mM Tris-HCl pH 8.3, 500 mM KCl , 20 mM MgCl ₂ ) and 2.5 μl of thermostable DNA polymerase 5 U / μl were mixed together, and sterilized ultrapure water was added thereto to make a liquid volume of 25 μl. When the unmethylated specific primer is used, the reaction solution is kept at 95 ° C. for 10 minutes, then at 95 ° C. for 30 seconds, then at 59 ° C. for 30 seconds, and further at 72 ° C. for 30 seconds. PCR was performed under the condition that the incubation was performed for 32 cycles. When the above methylation-specific primer is used, the reaction solution is kept at 95 ° C. for 10 minutes, then at 95 ° C. for 30 seconds, then at 62 ° C. for 30 seconds, and further at 72 ° C. for 30 minutes. PCR was performed under the condition of performing heat retention for 32 cycles with 1 cycle per second. In either case, after PCR, the PCR reaction solution containing the amplification product was subjected to 2% agarose gel electrophoresis. The results are shown in FIG. In the case of immortalized (normal) pancreatic ductal epithelial cell lines derived from humans (HPDE-4 / E6E7 and HPDE6-E6E7c), when an unmethylated specific primer is used (lane U), the amplified DNA band is Amplified DNA bands were not detected when methylation-specific primers were used (lane M). Therefore, in the case of human-derived immortalized (normal) pancreatic duct epithelial cell lines (HPDE-4 / E6E7 and HPDE6-E6E7c), at least base numbers 1282, 1284, 1301, 1365 of the base sequence represented by SEQ ID NO: 1, It was determined that the cytosines shown at 1378 and 1383, respectively, were not methylated. In the case of 7 types of pancreatic cancer cell lines (BXPc3, HPAF-II, Capan-2, MiaPaCa-2, Hs766T, PANC-1 and HPAC), when using unmethylated specific primers (lane U) No amplified DNA band was detected, and when a methylation specific primer was used (lane M), an amplified DNA band was observed. Therefore, it was determined that the cytosine represented by base numbers 1282, 1284, 1301, 1365, 1378, and 1383 of the base sequence represented by SEQ ID NO: 1 was methylated under these conditions.

Example 2 (Confirmation test of methylation status of p53-responsive gene 2 gene in pancreatic cancer tissue)
Human-derived pancreatic cancer tissue and normal pancreatic tissue around it [obtained by obtaining informed consent from the patient] Each of 12 specimens (Case 1 to Case 12) was subjected to SEDTA buffer [10 mM Tris-HCl (pH 8.0), 10 mM EDTA ( After adding 10 times volume of pH 8.0), 100 mM NaCl], this was homogenized. After adding proteinase K (Sigma) to 500 μg / ml and sodium dodecyl sulfate to 1% (w / v) to the obtained mixture, it was shaken at 55 ° C. for about 16 hours. After completion of the shaking, the mixture was extracted with phenol [saturated with 1M Tris-HCl (pH 8.0)] and chloroform. The aqueous layer was recovered, and NaCl was added to this to 0.5 N, followed by ethanol precipitation to recover the precipitate. The recovered precipitate was dissolved in TE buffer (10 mM Tris, 1 mM EDTA, pH 8.0), and RNase A (Sigma) was added to this so as to be 40 μg / ml, followed by incubation at 37 ° C. for 1 hour. The incubated mixture was extracted with phenol / chloroform. The aqueous layer was collected, and NaCl was added to this to 0.5 N, followed by ethanol precipitation to collect the precipitate (genomic DNA). The collected precipitate was rinsed with 70% ethanol to obtain genomic DNA.
The obtained genomic DNA was digested with the restriction enzyme BamHI, and then Clark et al., Nucl. Acids. Res., 22, 2990-2997, 1994; Herman et al., Pro. Natl. Acad. Sci. USA, 93, 9821-9826, 1996 The sodium bisulfite treatment was performed according to the method described in 1996. That is, restriction enzyme-treated genomic DNA (about 500 ng) was dissolved in distilled water to prepare 20 μl of genomic DNA solution. After adding about 1 μl of 6M sodium hydroxide (final concentration: about 0.3M), The mixture was incubated at 37 ° C. for 15 minutes. To this mixture, 0.6 mM hydroquinone (Sigma) was added to a final concentration of 0.5 mM, and sodium bisulfite (Sigma) was added to a final concentration of 3.1 M. Then, this was added at 95 ° C. for 30 seconds and at 50 ° C. for 15 minutes for one cycle. Insulation was performed for 15 cycles. DNA was purified from the incubated solution using Wizard DNA clean-up system (Promega). The purified DNA was dissolved in 50 μl of TE buffer, and sodium hydroxide was added to this to a final concentration of 0.3 M, and then the mixture was allowed to stand at room temperature for 5 minutes. Subsequently, precipitation (DNA) was collect | recovered by carrying out ethanol precipitation of the left-over mixture. The collected precipitate was suspended in 20 μl of TE buffer.

Using the obtained DNA as a template, PCR was performed using unmethylated specific primers U1 and U2 shown below or methylated specific primers M1 and M2. When the unmethylated specific primers U1 and U2 are used, 106 bp DNA corresponding to the base sequence after the bisulfite treatment of base numbers 1279 to 1384 of the base sequence shown in SEQ ID NO: 1 is amplified, When methylation-specific primers M1 and M2 are used, 103 bp DNA corresponding to the base sequence after the bisulfite treatment of base numbers 1281 to 1383 shown in SEQ ID NO: 1 is amplified.
<Unmethylated specific primer>
U1: 5'-TTTTGTGTAGGTTTTAGGGTTTT-3 '(SEQ ID NO: 2)
U2: 5'-CAACCCACATAACCAAAACA-3 '(SEQ ID NO: 3)
<Methylation specific primer>
M1: 5'-TCGCGTAGGTTTTAGGGTTTC-3 '(SEQ ID NO: 4)
M2: 5'-GACCCGCATAACCAAAACG-3 '(SEQ ID NO: 5)
As described in Example 1, the specificity of the methylation-specific primer and the non-methylation-specific primer was determined using the genomic DNA (1) of an immortalized (normal) pancreatic duct epithelial cell line (HPDE-4 / E6E7) and A part of this was treated with methylase SssI (NEB) and confirmed in genomic DNA (2).

As a PCR reaction solution, 25 ng of DNA as a template, 1 μl of the above primer solution of 20 pmol / μl, 2.5 μl of each 2 mM dNTP, 10 × buffer (100 mM Tris-HCl pH 8.3, 500 mM KCl , 20 mM MgCl ₂ ) and 2.5 μl of thermostable DNA polymerase 5 U / μl were mixed together, and sterilized ultrapure water was added thereto to make a liquid volume of 25 μl. When the unmethylated specific primer is used, the reaction solution is kept at 95 ° C. for 10 minutes, then at 95 ° C. for 30 seconds, then at 59 ° C. for 30 seconds, and further at 72 ° C. for 30 seconds. PCR was performed under the condition that the incubation was performed for 32 cycles. When the above methylation-specific primer is used, the reaction solution is kept at 95 ° C. for 10 minutes, then at 95 ° C. for 30 seconds, then at 62 ° C. for 30 seconds, and further at 72 ° C. for 30 minutes. PCR was performed under the condition of performing heat retention for 32 cycles with 1 cycle per second. In either case, after PCR, the PCR reaction solution containing the amplification product was subjected to 2% agarose gel electrophoresis. The results are shown in FIG. In 12 samples of normal human pancreatic tissue, an amplified DNA band was observed when an unmethylated specific primer was used (lane U), and when a methylated specific primer was used (lane M). No amplified DNA band was detected. Therefore, in the case of normal pancreatic tissue derived from human, it is determined that at least cytosine represented by base numbers 1282, 1284, 1301, 1365, 1378 and 1383 of the base sequence represented by SEQ ID NO: 1 is not methylated. It was. In 7 of 12 pancreatic cancer tissues, in addition to the DNA band amplified when using unmethylated specific primers (lane U), amplified when using methylated specific primers (lane M) The observed DNA band was observed. Therefore, under these conditions, at least cytosine represented by base numbers 1282, 1284, 1301, 1365, 1378, and 1383 of the base sequence represented by SEQ ID NO: 1 is methylated by canceration of a part of the tissue. It was judged.

Example 3 (Confirmation test of expression state of p53-responsive gene 2 gene in pancreatic cancer cell line and effect of methylation inhibitor on expression of the gene)
Seven human pancreatic cancer cell lines (BXPc3, HPAF-II, Capan-2, MiaPaCa-2, Hs766T, PANC-1 and HPAC) and immortalized (normal) pancreatic duct epithelial cell lines (HPDE-4 / E6E7 and HPDE6) -E6E7c7) was cultured in a dedicated medium until 70% confluent, and each cell was collected. Each collected cell (about 100 mg wet weight) was homogenized by mixing 1 ml of ISOGEN solution (Nippon Gene), and then 0.2 ml of chloroform was added to suspend it. After the suspension, the mixture was centrifuged (4 ° C., 15000 × g, 15 minutes) to recover the supernatant. After 0.5 ml of isopropanol was added to the collected supernatant and suspended, the precipitate (RNA) was collected by centrifugation (4 ° C., 15000 × g, 15 minutes). The recovered precipitate was rinsed with 75% ethanol and then dissolved in DEPC (diethyl pyrocarbonate) -treated water.
In addition, two human pancreatic cancer cell lines (PANC-1 and HPAC) were inoculated at a density of about 6 × 10 ⁵ cells / 10 cm plate and cultured using a dedicated medium. On the first day after the inoculation, methylation inhibitor 5-aza-2'-deoxycytidine (manufactured by Sigma) (hereinafter referred to as 5Aza-dC) was added to the medium to a concentration of 0.5 μM or 1 μM. Twenty-four hours after the addition of 5Aza-dC, the medium was replaced with the above medium to which 5Aza-dC was not added, and the culture was continued. Next, on the third day after inoculation, 5Aza-dC was similarly added to the medium. On day 4 after inoculation, cells were collected, and RNA was extracted and collected from the collected cells in the same manner as described above.
After 3 μg of the RNA thus obtained was treated with DNase I (Ambion), cDNA was synthesized using this as a template and Superscript II (Invitrogen) according to the protocol attached to the enzyme. MRNA of the p53-responsive gene 2 gene is obtained by performing Real Time PCR using the synthesized cDNA as a template and the p53-responsive gene 2 S and p53-responsive gene 2 A shown below as a primer pair. DNA derived from was amplified. In this case, as a control, PCR was performed using the above cDNA as a template and the following GAPDH S and GAPDH A as a primer pair, thereby deriving from mRNA of the Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene. DNA to be amplified was amplified.
<Primer (S: sense, A: antisense)>
p53-responsive gene 2 S: 5'-GCCGCAGACCTCCATCC-3 '(SEQ ID NO: 12)
p53-responsive gene 2 A: 5'-GCAATGTGTTCAAGTTCCTCAGC-3 '(SEQ ID NO: 13)
GAPDH S: 5'-AGGTGAAGGTCGGAGTCAACG-3 '(SEQ ID NO: 14)
GAPDH A: 5'-AGGGGTCATTGATGGCAACA-3 '(SEQ ID NO: 15)

As PCR reaction solution, 50 ng of cDNA as a template, 1 μl of each of the above 10 pmol / μl primer solutions, 4 μl of each 2.5 mM dNTP, 4 μl of 5 mM dUTP, and 10 × SYBR Green PCR Buffer Mix 5 μl, 25 μM MgCl ₂ 6 μl, thermostable DNA polymerase (AmpliTaq Gold) 5 U / μl 0.3 μl, AmpEraseUNG 0.5 μl, and add sterilized ultrapure water to make the volume 50 μl. Using. Real Time PCR was performed using iCycler Thermal Cycler (Bio-Rad Laboratories). When amplifying DNA derived from p53-responsive gene 2 gene and GAPDH gene mRNA, the reaction solution is kept at 95 ° C for 10 minutes, then at 95 ° C for 30 seconds, and at 59 ° C for 30 seconds. Real time PCR was performed at 72 ° C. for 30 seconds as one cycle, and the p53-responsive gene 2 gene and the GAPDH gene were quantified.
The results are shown in FIGS. In human immortalized (normal) pancreatic ductal epithelial cell lines (HPDE-4 / E6E7 and HPDE6-E6E7c7), DNA derived from mRNA of p53-responsive gene 2 gene was detected, whereas pancreatic cancer The DNA was not detected in any of the seven cell lines. That is, in the immortalized (normal) pancreatic duct epithelial cell lines derived from humans (HPDE-4 / E6E7 and HPDE6-E6E7c7), the expression of the p53-responsive gene 2 gene was confirmed, whereas in seven pancreatic cancer cell lines In any case, expression of the p53-responsive gene 2 gene was not observed.
In the case of PANC-1 and HPA cultured in the presence of 0.5 μM or 1 μM 5Aza-dC, DNA derived from mRNA of the p53-responsive gene 2 gene was detected. In addition, DNA derived from mRNA of GAPDH gene is an immortalized (normal) pancreatic duct epithelial cell line (HPDE-4 / E6E7 and HPDE6-E6E7c7) and pancreatic cancer cell line PANC cultured in the absence of 5Aza-dC. -1 and HPA, or in the case of PANC-1 and HPA cultured in the presence of 0.5 μM or 1 μM 5Aza-dC, were similarly detected. That is, in the case of pancreatic cancer cell lines PANC-1 and HPA, expression of the p53-responsive gene 2 gene was observed in the presence of a methylation inhibitor.
The above results revealed that the cytosine methylation in the pancreatic cancer cell line was inhibited by the methylation inhibitor and the p53-responsive gene 2 gene was expressed in the presence of the methylation inhibitor. .

  According to the present invention, a method for evaluating the degree of canceration of a mammal-derived specimen can be provided.

Immortalized (normal) pancreatic ductal epithelial cell lines (HPDE-4 / E6E7 and HPDE6-E6E7c7) and 7 pancreatic cancer cell lines (BXPc3, HPAF-II, Capan-2, MiaPaCa-2, Hs766T, PANC-1 And HPAC), and PCR was performed using genomic DNA treated with sodium bisulfite as templates, and the PCR reaction solution after PCR was analyzed by agarose gel electrophoresis. The names of the cells used are shown above. The figure described as HPDE4 / SssI shows DNA obtained by treating the genomic DNA of HPDE-4 / E6E7 with methylase SssI. Lane U: PCR reaction solution for PCR using unmethylated specific primer, Lane M: PCR reaction solution for PCR using unmethylated specific primer. Human-derived pancreatic cancer tissue and surrounding normal pancreatic tissue [obtained by obtaining informed consent from a patient] PCR was performed using genomic DNA prepared from each of 12 specimens and treated with sodium bisulfite as a template. It is the figure which showed the result of having analyzed the subsequent PCR reaction liquid by agarose gel electrophoresis. Case 1 to Case 12 showed specimens. Cancer is a pancreatic cancer tissue, and Normal is a surrounding normal pancreatic tissue. Lane U: PCR reaction solution for PCR using unmethylated specific primer, Lane M: PCR reaction solution for PCR using unmethylated specific primer. Seven human pancreatic cancer cell lines (BXPc3, HPAF-II, Capan-2, MiaPaCa-2, Hs766T, PANC-1 and HPAC) and immortalized (normal) pancreatic duct epithelial cell lines (HPDE-4 / E6E7 and HPDE6) -E6E7c7) shows the amount of p53-responsive gene 2 gene obtained by amplifying DNA derived from mRNA of p53-responsive gene 2 gene by Real Time PCR. The names of the cells used are shown at the bottom of the figure. The vertical axis shows the value obtained by dividing the amount of p53-responsive gene 2 gene by the amount of GAPDH gene. Immortalized (normal) pancreatic duct epithelial cell line (HPDE-4 / E6E7) and two human-derived pancreatic cancer cell lines added with methylation inhibitor 5Aza-dC at concentrations of 0, 0.5 μM or 1 μM In (PANC-1 and HPA), it is the figure which showed the amount of p53-responsive gene 2 genes obtained by amplifying DNA derived from mRNA of p53-responsive gene 2 gene by Real Time PCR. The names of the cells used are shown at the bottom of the figure. The vertical axis shows the value obtained by dividing the amount of p53-responsive gene 2 gene by the amount of GAPDH gene.

SEQ ID NO: 2
Oligonucleotide primer designed for PCR SEQ ID NO: 3
Oligonucleotide primer designed for PCR SEQ ID NO: 4
Oligonucleotide primer designed for PCR SEQ ID NO: 5
Oligonucleotide primer designed for PCR SEQ ID NO: 6
Oligonucleotide primer designed for PCR SEQ ID NO: 7
Oligonucleotide primer designed for PCR SEQ ID NO: 8
Oligonucleotide designed for probe SEQ ID NO: 9
Oligonucleotide designed for probe SEQ ID NO: 10
Oligonucleotide designed for probe SEQ ID NO: 11
Oligonucleotide designed for probe SEQ ID NO: 12
Oligonucleotide primer designed for PCR SEQ ID NO: 13
Oligonucleotide primer designed for PCR SEQ ID NO: 14
Oligonucleotide primer designed for PCR SEQ ID NO: 15
Oligonucleotide primers designed for PCR

Claims (14)

A method for assessing the presence of cancer cells in test body from the pancreas of mammals,
(1) a first step of measuring the methylation frequency of the p53-responsive gene 2 gene or the amount of the expression product contained in a sample derived from the pancreas of a mammal, and (2) the measured methylation frequency or expression product evaluation method characterized by comprising a quantity, a second step of determining the presence of cancer cells in the test body based on a difference obtained by comparing the control.   2. The evaluation method according to claim 1, wherein the specimen derived from the pancreas of a mammal is a cell.   The evaluation method according to claim 1, wherein the specimen derived from the pancreas of a mammal is a tissue. A method for assessing the presence of cancer cells in test body from the pancreas of mammals,
(1) a first step of measuring the methylation frequency of the p53-responsive gene 2 gene contained in a sample derived from the pancreas of a mammal, and (2) by comparing the measured methylation frequency with a control evaluation method characterized by having a second step of determining the presence of cancer cells in the test object based on a difference obtained. Evaluation method according to claim 4, wherein the analyte from the pancreas of mammals are cells. Evaluation method according to claim 4, wherein the sample derived from the pancreas of a mammal is woven set.   The methylation frequency of a cytosine in the nucleotide sequence represented by one or more 5'-CG-3 'existing in the nucleotide sequence in the promoter region, untranslated region or translated region of the gene The evaluation method according to claim 1, wherein:   The methylation frequency of a gene is the methylation frequency of cytosine in the base sequence represented by one or more 5′-CG-3 ′ present in the base sequence in the promoter region of the gene The evaluation method according to claim 1 or 4.   The methylation frequency of a gene is the methylation frequency of cytosine in the base sequence represented by one or more 5′-CG-3 ′ present in the base sequence in the untranslated region or translated region of the gene. The evaluation method according to claim 1, wherein:   Among the cytosines in the base sequence represented by 5′-CG-3 ′ present in the base sequence represented by SEQ ID NO: 1 in the methylation frequency of the gene, The methylation frequency of cytosine, which is the base number represented by any one or more of base numbers 1282, 1284, 1301, 1308, 1315, 1319, 1349, 1351, 1357, 1361, 1365, 1378 or 1383 The evaluation method according to claim 1, wherein: A method for assessing the presence of cancer cells in test body from the pancreas of mammals,
(1) a first step of measuring the amount of expression product of p53-responsive gene 2 gene contained in a specimen derived from the pancreas of a mammal; and (2) comparing the amount of the measured expression product with a control. evaluation method characterized by having a second step of determining the presence of cancer cells in the test body based on a difference obtained by. The evaluation method according to claim 11 , wherein the amount of the expression product of the p53-responsive gene 2 gene is the amount of the transcription product of the gene. The evaluation method according to claim 11 , wherein the amount of the expression product of the p53-responsive gene 2 gene is the amount of the translation product of the gene.   Use of methylated p53-responsive gene 2 gene as a marker for pancreatic cancer.

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