WO2011129494A1

WO2011129494A1 - Nucleolin specific aptamer and use thereof

Info

Publication number: WO2011129494A1
Application number: PCT/KR2010/006311
Authority: WO
Inventors: Jung-Hwan Lee; Soon-Hag Kim; Mi-Jin Kwon; Hyun-Gu Kang; Sung-Ho Ryu; Jong-In Kim; Youn-Dong Kim; Young-Chan Chae; Sung-Key Jang; Jong-Hun Im; Sun-Hak Lee; Hye-Jung Lee; Eun-Jung Jang; Ki Seok Kim
Original assignee: Posco Co Ltd; POSTECH Academy Industry Foundation
Current assignee: POSTECH Academy Industry Foundation; Posco Holdings Inc
Priority date: 2010-04-14
Filing date: 2010-09-15
Publication date: 2011-10-20
Anticipated expiration: 2012-10-14
Also published as: US20100317723A1; KR20130095635A; US9018185B2; US8569252B2; US9018186B2; US20140213636A1; KR101671863B1; US20140093886A1

Abstract

Improved G-rich oligonucleotide (GRO) aptamers specific to nucleolin, a method of preparing the aptamers, and a use of the aptamers for diagnosing and/or treating a nucleolin-associated disease, are provided.

Description

NUCLEOLIN SPECIFIC APTAMER AND USE THEREOF

TECHNICAL FIELD

The present invention relates to improved G-rich oligonucleotide (GRO) aptamers specific to nucleolin, a method of preparing the aptamers and a use of the aptamers for diagnosing and/or treating a nucleolin-associated disease.

BACKGROUND

Nucleolin is a protein that is expressed at elevated levels in transformed cells.

Tumor cells have been shown to present nucleolin on the cell surface as well as expressing it in the cytoplasm and nucleus. Nucleolin plays multiple roles in the cell and is involved in ribosome biogenesis, cell growth, and DNA replication.

Aptamers are about 60~80mers of synthetic ribonucleic acid(RNA) or deoxyribonucleic acid(DNA) oligonucleotides which are known to be discovered by the process called systematic evolution of ligands by exponential enrichment(SELEX) based on high affinity and specific molecular fit with their targets of interest.

Aptamer have recently preferred to be applied for diagnosing and treating cancers as imaging target agents rather than monoclonal antibodies due to the following characteristics: inexpensive, efficient and rapid for production, highly stable for long- term storage, versatile molecules that can be easily modified with imaging probe, small size (8-15 kDa) resulting low immune risk and better penetration into target tissues in vivo, and high affinity molecular probe.

A large number of aptamers targeting cancer-related proteins, such as Wilim's tumor protein 1 (WT1), transcription factor l (TCF-l), human epidermal growth factor receptor 3(HER-3), prostate-specific membrane antigene(PSMA), tenascin-C, nucleolin, pigpen and vascular endothelial growth factor(VEGF), have been developed to target and image cancers.

Some chemical modifications on the ribose backbone of aptamer nucleotides using 2'-amino or 2'-fluoro pyrimidines have been in situ and in vitro studied with the existing aptamers to be resistant to nucleases, more capable of transfer across membranes or more capable of specific binding to the target of interest, but they influence the structure of aptamers, resulting in the loss of aptamer properties. SUMMARY OF THE INVENTION

The present inventors found that chemically 5 -modified deoxyuridine (dU)- containing GR029A(SEQ ID NO: 1) and AS1411 (SEQ ID NO: 2) exhibit much higher affinity to nucloelin protein than that of non-modified AS 1411 and GR029A in various cancer cell types, to complete the present invention.

An embodiment provides a nucleolin-specific aptamer having the nucleotide sequence of SEQ ID NO: 1 or 2, wherein one or more thymidines (T) are independently substituted with a modified deoxyuridine (dU), and wherein the modified dU is a deoxyuridine having a hydrophobic group at 5' position. The modified deoxyuridine may be 5-(N-benzylcarboxyamide)-2'-deoxyuridine (BzdU), 5-(N- naphthylcarboxyamide)-2' -deoxyuridine (NapdU), or 5-(N-4- pyrrolebenzylcarboxyamide)-2'-deoxyuridine (4-PBdU).

Another embodiment provides a pharmaceutical composition containing the nucleolin-specific aptamer. The pharmaceutical composition may a nucleolin inhibitor or agent for inhibiting an abnormal hyper-proliferation of cell, for example an anticancer agent.

Another embodiment provides a method of diagnosing a hyper-proliferative cell disorder, such as cancer using the nucleolin-specific aptamer labeled with a detectable label.

Another embodiment provides a method of treating a nucleolin-associated cancer using the nucleolin-specific aptamer.

Another embodiment provides a method of inhibiting an abnormal hyper- proliferation of call using the nucleolin-specific aptamer.

Still another embodiment provides a method of inhibiting nucleolin using the nucleolin-specific aptamer. DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to improved G-rich oligonucleotide (GRO) aptamers specific to nucleolin, a method of preparing the aptamers and a use of the aptamers for diagnosing and/or treating a cancer.

GR029A(TTTGGTGGTGGTGGTTGTGGTGGTGGTGG; SEQ ID NO: 1) and AS1411 (GGTGGTGGTGGTTGTGGTGGTGGTGG; SEQ ID NO: 2) are G-rich oligonucleotide (GRO) aptamers comprising a single-strand DNA chain of 29 or 26 bases with unmodified phosphodiester linkages. G-rich oligonucleotide (GROs) are a class of non-antisense nucleic acids that exhibit potent anti-proliferative effects against almost every cancer cell type that was tested and thus, appears to have broad therapeutic potential. GR029A and AS 1411 have been known to bind to the nucleolin protein, which is expressed at elevated levels in transformed cells. Almost all tumor cells have been shown to present nucleolin on the cell surface as well as expressing it in the cytoplasm and nucleus. Nucleolin plays multiple roles in the cell and is involved in ribosome biogenesis, cell growth and DNA replication. The mechanism of GRO antiproliferative activity appears to depend on their binding to the nucleolin protein.

GR029A and AS 1411 self-anneal to form a biomolecular quardruplex structure that is extremely stable and resistant to degradation by serum enzyme. GR029A and AS 1411 have shown activity against a wide range of solid and blood cancer cell lines in preclinical experiments and could therefore have potential against a variety of human cancers.

The inventors directly applied chemically modified pyrimidine-based nucleoside(s) (e.g., deoxyuridine (dU), deoxycytidine (dC), uridine (U), cytidine (C), etc.) into the GRO aptamers (AS 141 land GR029A), which binds to nucleolin protein expressed in abnormally hyperproliferative cells, such as cancer cells, to find a type of GRO aptamer more capable of specific binding to abnormally hyperproliferative cells, such as cancer cells. The modified nucleoside may be a pyrimidine nucleoside modified by a hydrophobic group, such as benzyl group, a naphthyl group, or a pyrrolebenzyl group, at its 5' position. Modified nucleoside may be exemplified as 5-(N- benzylcarboxyamide)-2'-deoxyuridine(called BzdU), 5-(/V-naphthylcarboxyamide)-2'- deoxyuridine(called NapdU), 5-(N-4-pyrrolebenzylcarboxyamide)-2'- deoxyuridine(called 4-PBdU), 5-(N-benzylcarboxyamide)-2'-deoxycytidine (called BzdC), 5-(N-naphthylcarboxyamide)-2'-deoxycytidine (called NapdC), 5-(N-4- pyrrolebenzylcarboxyamide)-2'-deoxycytidine (called 4-PBdC), 5-(N- benzylcarboxyamide)-2'-uridine(called BzU), 5-(N-naphthylcarboxyamide)-2'- uridine(called NapU), 5-(N-4-pyrrolebenzylcarboxyamide)-2'-uridine(called 4-PBU), 5- ( V-benzylcarboxyamide)-2'-cytidine (called BzC), 5-(N-naphthylcarboxyamide)-2'- cytidine (called NapC), 5-(N-4-pyrrolebenzylcarboxyamide)-2'-cytidine (called 4-PBC), and the like.

In the concrete embodiment, several hundred compounds of GRO aptamer

(AS 1411 and GR029A)-containing modified dU such as BzdU, NapdU and 4-PBdU (BzdU-containing-, NapdU-containing- and 4-PBdU-containing GRO aptamer) were exemplarily synthesized by randomly substituting one to twelve thymidines(T) in GR029A (SEQ ID NO: 1) and one to nine thymidine in AS1411 (SEQ ID NO: 2) with modified dUs. The modified pyrimidine nucleoside having a hydrophobic group, such as benzyl group, a naphthyl group, or a pyrrolebenzyl group, at its 5' position can be sufficiently exemplified by the modified dUs as described above. Several statistically quantified fluorescence measurement, qualified confocal imaging analysis, FACS analysis, and MTT assay demonstrated with replaced T by modified dUs of a particular position of GRO aptamers (AS 1411 and GR029A). The results show that the modified dU-containing GRO aptamers significantly increased the targeting affinity to various cell lines, implying that the position and number of substituents in GRO aptamers (AS 1411 and GR029A) are critical parameters to improve the aptamer function. In the present invention, it is revealed that chemical modification on the existing aptamers would enhance the binding and targeting affinity to targets of interest without additional SELEX procedure.

The inventors also found that AS 1411 , which is a modified form of GR029A by deletion of 'ΤΤΤ' present at 5' end of GR029A, has similar or higher affinity to nucleolin compared to GR029A, indicating that the three bases present at 5' end of GR029A (SEQ ID NO: 1) play no important role in the affinity to nucleolin. Therefore, the sequence and/or presence/absence of the three bases may not matter in the present invention, and thus following SEQ ID NO: 3 can also be included in the present invention:

NGGTGGTGGTGGTTGTGGTGGTGGTGGN (SEQ ID NO: 3)

wherein 'N' may be absent or 1 to 20 nucleosides, preferably 1 to 10 nucleosides, which is independently selected from the group consisting of adenosine(A), thymidine(T)/uridine(U), cytidine(C), and guanosine(G).

Hereinafter, the present invention is described in detail.

In an aspect, a nucleolin-specific aptamer is provided. As used herein, 'nucleolin-specific aptamer' means an aptamer having a specifically high affinity to nucleolin protein, thereby being capable of specifically binding to nucleolin protein.

The aptamer has the nucleotide sequence of SEQ ID NO: 3, preferably SEQ ID NO: 1 or 2, wherein one or more thymidines (T) are independently substituted with a modified pyrimidine nucleoside (e.g., deoxyuridine (dU), deoxycytidine (dC), uridine (U), cytidine (C), etc.). The modified pyrimidine nucleoside may be a pyrimidine nucleoside having a hydrophobic group at 5' position. The hydrophobic group may have a benzyl group, a naphthyl group, or a pyrrolebenzyl group. By such modification of pyrimidine nucleoside with a hydrophobic group, the affinity of the aptamer to nucleolin is considerably improved compared with that of non-modified aptamer.

In a concrete embodiment, the hydrophobic group may be benzylcarboxyamide, naphthylcarboxyamide, pyrrolebenzylcarboxyamide and the like, and accordingly, the modified pyrimidine nucleoside may be 5-(N-benzylcarboxyamide)-2'- deoxyuridine(called BzdU), 5-(N-naphthylcarboxyamide)-2'-deoxyuridine(called NapdU), 5-(N-4-pyrrolebenzylcarboxyamide)-2'-deoxyuridine(called 4-PBdU), 5-(N- benzylcarboxyamide)-2'- deoxycytidine (called BzdC), 5-(N-naphthylcarboxyamide)- 2 '-deoxycytidine (called NapdC), 5-(N-4-pyrrolebenzylcarboxyamide)-2'- deoxycytidine (called 4-PBdC), 5-(N-benzylcarboxyamide)-2'-uridine(called BzU), 5- (N-naphthylcarboxyamide)-2'-uridine(called NapU), 5-(N-4- pyrrolebenzylcarboxyamide)-2'-uridine(called 4-PBU), 5-(N-benzylcarboxyamide)-2'- cytidine (called BzC), 5-(N-naphthylcarboxyamide)-2'-cytidine (called NapC), 5-(N-4- pyrrolebenzylcarboxyamide)-2'-cytidine (called 4-PBC), and the like.

The inventors found that the position of thymidine to be modified is also important to improve the affinity to nucleolin. The modification of thymidines present at central region of the aptamer considerably contributes to improve the affinity to nucleolin. The central region may be a loop site of the aptamer. More specifically, the central region may be 12^th to 18^th positions, preferably 15^th and 16^th positions of SEQ ID NO: 1 , or 9^th to 18^th positions, preferably 12^th and 13^th positions of SEQ ID NO: 2 or SEQ ID NO: 3 (when the positions are counted starting from 'G' after 'N' at 5'-end). As shown in Fig. 23, it is found that a more modification on any position in addition to central double modified dU-containing GR029A or AS 1411 did not increase binding to nucleolin on various cancer cell lines, indicating that the central region (2 bases) of the aptamer may be a critical region for the modification of the aptamer to effect on the affinity of the aptamer to nucleolin.

Therefore, in a preferable embodiment, at least two thymidines present in 12^th to 18^th positions, preferably at 15^th and 16^th positions of SEQ ID NO: 1 , or present in 9^th to 18^th positions, preferably at 12^th and 13^th positions of SEQ ID NO: 2 or SEQ ID NO: 3 (when the positions are counted starting from 'G' after 'N' at 5 '-end) are substituted with the modified deoxyuridine. In a concrete embodiment, the aptamer has the nucleotide sequence of SEQ ID NO: 1 , wherein 2 to 12 thymidines essentially comprising two thymidines present in 12 to 18 positions, preferably at 15 and 16 positions are replaced with modified deoxyuridines. In another concrete embodiment, the aptamer has the nucleotide sequence of SEQ ID NO: 2 or SEQ ID NO: 3 (when the positions are counted starting from 'G' after 'N' at 5'-end), wherein 2 to 9 thymidines essentially comprising two thymidines present in 9^th to 18^th positions, preferably at 12^th and 13^th positions are replaced with modified deoxyuridines.

In another aspect, a method of preparing the nucleolin-specific aptamer according to the present invention is provided. The method may comprise the steps of replacing one or more thymidines (T) present in the nucleotide sequence of SEQ ID NO: 1 or 2 with the modified pyrimidine nucleoside(s) (e.g., dU, dC, U, C, etc.) as described above.

Nucleolin functions as a marker of hyper-proliferative cells, such as cancer cells, since nucleolin is specifically expressed on surface of hyper-proliferative cells, such as cancer cells. Therefore, the nucleolin-specific aptamer according to the present invention can be useful in diagnosing various hyper-proliferative cell disorders.

As used herein, the hyper-proliferative cell disorder refers to excess (abnormally high) cell proliferation (abnormal hyper-proliferation of cell), relative to that occurring with the same type of cell in the general population and/or the same type of cell obtained from a patient at an earlier time. The term denotes malignant as well as non-malignant cell populations. Such disorders have an excess cell proliferation of one or more subsets of cells, which often appear to differ from the surrounding tissue both morphologically and genotypically. The excess cell proliferation can be determined by reference to the general population and/or by reference to a particular patient, e.g. at an earlier point in the individual's life. Hyper-proliferative cell disorders can occur in different types of animals and in humans, and produce different physical manifestations depending upon the affected cells. The hyper-proliferative cell disorders may include various cancers.

Therefore, in another aspect, a composition for diagnosing a hyper-proliferative cell disorder, such as a cancer, containing the nucleolin-specific aptamer according to the present invention as an active ingredient, and a method of diagnosing a hyper- proliferative cell disorder, such as a cancer, using the nucleolin-specific aptamer, are provided. Alternatively, a use of the nucleolin-specific aptamer according to the present invention in diagnosing a hyper-proliferative cell disorder is provided. The method may comprise the steps of:

contacting the nucleolin-specific aptamer with a sample from a subject, wherein the aptamer is labeled with a detectable label; and

detecting a signal from the label.

In the method, the subject is determined as having a hyper-proliferative cell disorder, such as a cancer, when the signal is detected. The nucleolin specific aptamer is as described above. The subject to be diagnosed may be from any mammalian species, e.g. primate sp., particularly humans; rodents including mice, rats and hamsters; rabbits; equines, bovines, canines, felines; and the like. Animal models may be of interest for experimental investigations, providing a model for treatment of human disease. The sample may be any bio-sample from the subject, such as cells, tissues, blood, body fluid, and the like.

The cancer that can be diagnosed by the present invention may be any nucleolin-associated cancer including any solid cancers and blood cancers, including leukemias, lymphomas (Hodgkins and non-Hodgkins), and other myeloproliferative disorders; carcinomas of solid tissue, sarcomas, melanomas, adenomas, hypoxic tumors, squamous cell carcinomas of the mouth, throat, larynx, or lung, genitourinary cancers such as cervical and bladder cancer, hematopoietic cancers, head and neck cancers, and nervous system cancers, benign lesions such as papillomas, and the like. The nucleolin-associated cancer may be selected from the group consisting of leukemia, lymphoma, breast cancer, liver cancer, gastric cancer, ovarian carcinoma, cervical carcinoma, glioma cancer, colon cancer, lung cancer, pancreas cancer, prostate cancer, liver cancer, stomach cancer, uterine cancer, bladder cancer, thyroid cancer, ovary cancer, melanoma cancer, cervical cancer, and the like, but not be limited thereto.

The label may be any one which can be detectable by any conventional means. For example, the label may be one or more selected from the group consisting of a fluorescence material, infrared material, quantum dots, ion oxide bead, PET probe (e.g., ⁶⁸gallium), Tl MR probe including iron oxide (e.g., Fe₃0₄), T2 MR probe (e.g., MnFe₂0₄, or GdFe₂0₄ nanoparticles), and the like, but not be limited thereto.

When the labeled-nucleolin specific aptamer is contacted with the sample, and then, non-reacted aptamer is removed (for example, by washing), if nucleolin is present in the sample (i.e., the subject having abnormally hyper-proliferative cells, such as cancer cells, resulted from the presence of nucleolin), the aptamer specifically binds to nucleolin on cells, and the signal from the label attached to the aptaemer is detected, allowing to diagnose a hyper-proliferative cell disease, such as a cancer, as described above. Nucleolin is associated with cell cycle and cell division, and thus, when the nucleolin specific aptamer of the present invention binds to nucleolin, thereby interfering with the function of nucleolin, resulting in interfering with the cell cycle, arresting cell-cycle, for example at the S-phase, inhibiting DNA replication, inducing cell death, etc. Therefore, the nucleolin specific aptamer of the present invention can function as an inhibitor of nucleolin, and agent for inhibiting hyperproliferation of cell, and thereby being useful in treating a hyper-proliferative cell disease, such as cancer, as described above.

Therefore, in another aspect, a composition for inhibiting nucleolin, containing the nucleolin-specific aptamer as an active ingredient, and a method of inhibiting nucleolin using the nucleolin-specific aptamer, are provided. Alternatively, a use of the nucleolin-specific aptamer in inhibiting nucleolin is provided. The method may comprise the step of administering the nucleolin-specific aptamer according to the present invention to a subject or a sample comprising nucleolin-expressing cells. In addition, a method of inhibiting hyperproliferation of cell cased by nucleolin using the nucleolin-specific aptamer is also provided. The method may comprise the step of administering the nucleolin-specific aptamer of Claim 1 to a subject or a sample comprising nucleolin-expressing cells.

The nucleolin-specific aptamer is as described above. The subject may be from any mammalian species, e.g. primate sp., particularly humans; rodents including mice, rats and hamsters; rabbits; equines, bovines, canines, felines; and the like, who is in need of the inhibition of nucleolin and/or hyperpriliferation of cell caused by nucleolin. Animal models may be of interest for experimental investigations, providing a model for treatment of human disease. The sample may be any bio-sample from the subject, such as cells, tissues, blood, body fluid, and the like.

In another aspect, a composition for inhibiting hyperproliferation of cell cased by nucleolin, containing the nucleolin-specific aptamer as an active ingredient, and a method of inhibiting an abnormal hyper-proliferation of cell using the nucleolin-specific aptamer according to the present invention, are provided. Alternatively, a use of the nucleolin-specific aptamer in inhibiting hyperproliferation of cell cased by nucleolin is provided. In addition, a composition, a use, and a method of treating a hyper- proliferative cell disorder, such as a cancer (nucleolin-associated cancer), using the nucleolin-specific aptamer according to the present invention, are also provided.

The method may comprise the step of administering an effective amount of the nucleolin-specific aptamer to a subject who needs the inhibition of the abnormal hyper- proliferation of cell and/or the treatment of the abnormal hyper-proliferation of cell, for example, the treatment of a cancer. As described above, the nucleolin-specific aptamer has an excellent affinity to nucleolin to inhibit nucleolin, thereby exhibiting a treatment effect for cell hyper-proliferation, such as a cancer.

The nucleolin specific aptamer is as described above. The subject may be from any mammalian species, e.g. primate sp., particularly humans; rodents including mice, rats and hamsters; rabbits; equines, bovines, canines, felines; and the like, who needs the inhibition of the abnormal hyper-proliferation of cell and/or the treatment of the abnormal hyper-proliferation of cell, for example, the treatment of a cancer. Animal models may be of interest for experimental investigations, providing a model for treatment of human disease. The cancer that can be treated by the present invention may be any nucleolin-associated cancer including any solid cancers and blood cancers, including leukemias, lymphomas (Hodgkins and non-Hodgkins), and other myeloproliferative disorders; carcinomas of solid tissue, sarcomas, melanomas, adenomas, hypoxic tumors, squamous cell carcinomas of the mouth, throat, larynx, and lung, genitourinary cancers such as cervical and bladder cancer, hematopoietic cancers, head and neck cancers, and nervous system cancers, benign lesions such as papillomas, and the like. The nucleolin-associated cancer may be selected from the group consisting of leukemia, lymphoma, breast cancer, liver cancer, gastric cancer, ovarian carcinoma, cervical carcinoma, glioma cancer, colon cancer, lung cancer, pancreas cancer, prostate cancer, liver cancer, stomach cancer, uterine cancer, bladder cancer, thyroid cancer, ovary cancer, melanoma cancer, cervical cancer, and the like, but not be limited thereto.

The effective amount means an amount exhibiting a therapeutic effect on the inhibition of nucleolin or hyper-proliferation of cell, for example treating a cancer, and may be properly controlled depending on the condition of the subject and/or severity of disease. The effective amount can be administered in one or more administrations. The administration may be performed by oral or parenteral (e.g., intravenous, subcutaneous, intramuscular, and the like) pathway, but not limited thereto.

In still another aspect, a pharmaceutical composition containing the nucleolin- specific aptamer according to the present invention as an active ingredient is provided. The pharmaceutical composition may a nucleolin inhibitor or agent for inhibiting an abnormal hyper-proliferation of cell, for example an anticancer agent. BRIEF DESCRIPTION OF THE FIGURES

Fig.l shows a schematic diagram to synthesize nucleolin aptamer containing 5- (N-benzylcarboxyamide)-2'-deoxyuridine (BzdU-containing GR029A), wherein Z indicates that thymidines in GR029A oligonucleotides were substituted with 5-(N- benzylcarboxyamide)-2'-deoxyuridine(BzdU).

Fig. 2 shows results of fluorescence analysis of Cy3-labeled BzdU-containing

GR029A compounds targeting C6 cells.

Fig. 3 shows confocal microscopy images of Cy3 -labeled BzdU-containing GR029A targeting C6 cells.

Fig. 4 shows fluorescence intensities measured by fluorescence analysis of numbers 1642-39, 1642-51, 1642-19 and Cy3-labeled GR029A, and Cy3-labeled CR029A (the control form of GR029A labeled with Cy3) in HeLa and CHO cells.

Figs. 5A and 5B show confocal microscopy images in HeLa cells (5A) and CHO cells (5B).

Fig. 6 shows cell viabilities measured by MTT assay to show anti-proliferation effects.

Fig. 7 shows results of fluorescence analysis of Cy3 -labeled NapdU-containing GR029A compounds targeting C6 cells.

Fig. 8 shows results of a flow cytometric analysis of MDA-MB231 cells treated with NapdU -containing AS 1411.

Fig. 9 shows results of a flow cytometric analysis of MDA-MB231 cells treated with 4-PBdU -containing AS 1411.

Fig. 10 shows results of a flow cytometric analysis of HepG2 cells treated with NapdU -containing AS 1411.

Fig. 11 shows results of a flow cytometric analysis of HepG2 cells treated with 4-PBdU -containing AS 1411.

Fig. 12 shows results of a flow cytometric analysis of AGS cells treated with NapdU -containing AS 1411.

Fig. 13 shows results of a flow cytometric analysis of AGS cells treated with 4- PBdU -containing AS 141 1.

Fig. 14 shows results of a flow cytometric analysis of OVCAR-3 cells treated with NapdU -containing AS 1411.

Fig. 15 shows results of a flow cytometric analysis of OVCAR-3 cells treated with 4-PBdU -containing AS 1411.

Fig. 16 shows results of a flow cytometric analysis of HeLa cells treated with NapdU -containing AS 1411.

Fig. 17 shows results of a flow cytometric analysis of HeLa cells treated with 4- PBdU -containing AS 1411.

Fig. 18 shows results of a flow cytometric analysis of U87MG cells treated with NapdU -containing AS 1411.

Fig. 19 shows results of a flow cytometric analysis of U87MG cells treated with

4-PBdU -containing AS 1411.

Fig. 20 shows results of a flow cytometric analysis of NIHT3 cells treated with NapdU -containing AS 1411.

Fig. 21 shows results of a flow cytometric analysis of NIHT3 cells treated with 4-PBdU -containing AS 1411.

Fig. 22 shows results of a quantification of FACS analysis for various cell lines.

Fig. 23 shows activities between central double modification and a more modification of AS 1411.

Fig. 24 shows specificities of all NapdU-containing AS 1411(1642-132) and central double NapdU-containing AS 1411 (1642- 161) in cancer and normal cell lines determined with FACS analysis.

Fig. 25 shows specificities of all 4-PBdU-containing AS 141 1(1642-206) and central double 4-PBdU-containing AS 1411 (1642-177) in cancer and normal cell lines determined with FACS analysis.

Fig. 26 shows results of a quantification of FACA analysis data of AS 1411 and central modified dU-containing AS 1411 binding to nucleolin on various cell lines

Fig. 27 shows MR images of turmor-bearing mice before and after tail-vein injection of central double NapdU-containing AS 1411(1642-161), wherein dark signal intensities at tumor sites were detected in AS 141 1 -MF particle- and modified AS 1411- MF-injected mice (arrowhead).

Fig. 28 shows the effect of central double NapdU-containing AS 1411 on the cell viability of MDA-MB231 breast cancer cells.

Fig. 29 shows the relation between structure and activity of central double modified dU-containing AS1411 (or GR029A).

EXAMPLES

A better understanding of the present invention may be obtained in light of the following examples that are set forth to illustrate, but are not to be construed to limit, the present invention.

EXAMPLE 1: Preparation of Cy3-labled modified dU AS1411 and GR029A

1.1: Design of Cy3-labied modified dU AS1411 and GR029A

Forty-seven different compounds of Cy3 -labeled BzdU-containing GR029A were designed and synthesized. The GR029A oligonucleotides

(TTTGGTGGTGGTGGTTGTGGTGGTGGTGG, SEQ ID NO: 1) incorporated with 5- (N-benzylcarboxyamide)-2'-deoxyuridine(BzdU) and labeled with Cy3 were prepared according to the following synthesis procedure of Example 1.2. One to twelve thymidines in GR029A oligonucleotides were randomly replaced with BzdU (see Fig. 1). Fig. 1 is a schematic diagram to synthesize nucleolin aptamer containing 5- N- benzylcarboxyamide)-2'-deoxyuridine (BzdU-containing GR029A), wherein Z indicated where thymidines in GR029A oligonucleotides were substituted with 5-(N- benzylcarboxyamide)-2 ' -deoxyuridine(BzdU) .

The designed forty-seven Cy3 -labeled BzdU-containing GR029A are summarized in Table 1.

(Table 1) A list of modified GR029A containing Bz at 5 position of dU (5-(N- benzylcarboxyamide)-2'-deoxyuridine, BzdU)

Comp. No. Cy3-labeled Modified dU- GR029A Sequence (5'→3') Cal. MS Obs. MS

Cy3- 1642-8 Cy3-labeled-ZTTGGTGGTGGTGGTTGTGGTGGTGGTGG 9811.71 9812.32

Cy3-1642-9 Cy3-labeled-TZTGGTGGTGGTGGTTGTGGTGGTGGTGG 9811.71 9811.72

Cy3-1642-10 Cy3-labeled-TTZGGTGGTGGTGGTTGTGGTGGTGGTGG 981 1.71 9811.92

Cy3-1642-l l Cy3-labeled-TTTGGZGGTGGTGGTTGTGGTGGTGGTGG 9811.71 9812.27

Cy3-1642-12 Cy3- labeled-TTTGGTGGZGGTGGTTGTGGTGGTGGTGG 9811.71 981 1.83

Cy3-1642-13 Cy3 - labeled-TTTGGTGGTGGZGGTTGTGGTGGTGGTGG 9811.71 9812.38

Cy3-1642-14 Cy3- labeled-TTTGGTGGTGGTGGZTGTGGTGGTGGTGG 9811.71 9812.18

Cy3-1642-15 Cy3- labeled-TTTGGTGGTGGTGGTZGTGGTGGTGGTGG 9811.71 9812.22

Cy3-1642-16 Cy3- labeled-TTTGGTGGTGGTGGTTGZGGTGGTGGTGG 9811.71 9812.01

Cy3-1642-I 7 Cy3- labeled-TTTGGTGGTGGTGGTTGTGGZGGTGGTGG 9811.71 9812.10

Cy3-1642-18 Cy3- labeled-TTTGGTGGTGGTGGTTGTGGTGGZGGTGG 981 1.71 9812.69

Cy3-1642-19 Cy3- labeled-TTTGGTGGTGGTGGTTGTGGTGGTGGZGG 9811.71 981 1.78

Cy3- 1642-21 Cy3- labeled-TZZGGTGGTGGTGGTTGTGGTGGTGGTGG 9930.82 9931.40

Cy3- 1642-23 Cy3- labeled-ZZZGGTGGTGGTGGTTGTGGTGGTGGTGG 9930.82 9931.24

Cy3- 1642-24 Cy3 - labeled-TTTGGTGGTGGTGGTTGTGGTGGZGGZGG 9930.82 9931.02

Cy3- 1642-25 Cy3- labeled-TTTGGTGGTGGTGGTTGTGGZGGTGGZGG 9930.82 9931.10

Cy3- 1642-26 Cy3- labeled-TTTGGTGGTGGTGGTTGZGGTGGTGGZGG 9930.82 9931.81

Cy3- 1642-27 Cy3- labeled-TTTGGTGGTGGTGGTZGTGGTGGTGGZGG 9930.82 9930.93

Cy3- 1642-28 Cy3- labeled-TTTGGTGGTGGTGGZTGTGGTGGTGGZGG 9930.82

Cy3- 1642-29 Cy3- labeled-TTTGGTGGTGGZGGTTGTGGTGGTGGZGG 9930.82

Cy3- 1642-30 Cy3- labeled-TTTGGTGGZGGTGGTTGTGGTGGTGGZGG 9930.82

Cy3- 1642-31 Cy3- labeled-TTTGGZGGTGGTGGTTGTGGTGGTGGZGG 9930.82 9931.81 Cy3- 1642-32 Cy3- labeled-TTZGGTGGTGGTGGTTGTGGTGGTGGZGG 9930.82

Cy3- 1642-33 Cy3- labeled-TZTGGTGGTGGTGGTTGTGGTGGTGGZGG 9930.82

Cy3-1642-34 Cy3- labeled-ZTTGGTGGTGGTGGTTGTGGTGGTGGZGG 9930.82

Cy3-1642-35 Cy3- labeled-TTTGGTGGTGGTGGZZGTGGTGGTGGZGG 10049.93

Cy3- 1642-36 Cy3- labeled-TZZGGTGGTGGTGGTTGTGGTGGTGGZGG 10049.93

Cy3-1642-37 Cy3- labeled-ZZTGGTGGTGGTGGTTGTGGTGGTGGZGG 10049.93 10051.40

Cy3- 1642-39 Cy3- labeled-TTTGGTGGTGGTGGZZGTGGTGGTGGTGG 9930.82

Cy3- 1642-40 Cy3- labeled-TTTGGTGGTGGTGGZZGZGGTGGTGGTGG 10049.93

Cy3- 1642-41 Cy3- labeled-TTTGGTGGTGGTGGZZGTGGZGGTGGTGG 10049.93

Cy3- 1642-42 Cy3- labeled-TTTGGTGGTGGTGGZZGTGGTGGZGGTGG 10049.93

Cy3- 1642-43 Cy3- labeled-TTTGGTGGTGGZGGZZGTGGTGGTGGTGG 10049.93

Cy3- 1642-44 Cy3- labeled-TTTGGTGGZGGTGGZZGTGGTGGTGGTGG 10049.93

Cy3- 1642-45 Cy3- labeled-TTTGGZGGTGGTGGZZGTGGTGGTGGTGG 10049.93 10050.99

Cy3-1642-46 Cy3- labeled-TTZGGTGGTGGTGGZZGTGGTGGTGGTGG 10049.93

Cy3- 1642-47 Cy3- labeled-TZTGGTGGTGGTGGZZGTGGTGGTGGTGG 10049.93

Cy3- 1642-48 Cy3- labeled-ZTTGGTGGTGGTGGZZGTGGTGGTGGTGG 10049.93

Cy3- 1642-49 Cy3- labeled-TZZGGTGGTGGTGGZZGTGGTGGTGGTGG 10169.04

Cy3- 1642-50 Cy3- labeled-ZZTGGTGGTGGTGGZZGTGGTGGTGGTGG 10169.04

Cy3-1642-51 Cy3- labe!ed-ZTZGGTGGTGGTGGZZGTGGTGGTGGTGG 10169.04

Cy3-1642-52 Cy3- labeled-ZZZGGTGGTGGTGGZZGTGGTGGTGGTGG 10288.15 10288.41

Cy3- 1642-53 Cy3- labeled-TTTGGTGGTGGZGGTTGZGGTGGTGGTGG 9930.82

Cy3- 1642-54 Cy3- labeled-TTTGGTGGZGGTGGTTGTGGZGGTGGTGG 9930.82

Cy3- 1642-55 Cy3- labeled-TTTGGZGGTGGTGGTTGTGGTGGZGGTGG 9930.82

Cy3-1642-56 Cy3- labeled-TTTGGTGGZGGZGGTTGZGGZGGZGGTGG 10288.15

Cy3- 1642-57 Cy3- labeled-TTTGGZGGZGGZGGTTGZGGZGGTGGZGG 10407.26

Cy3-1641- Cy3- labeled-TTTGGTGGTGGTGGTTGTGGTGGTGGTGG 9692.6 0 9693.85

3(GR029A)

Cy3-1641- Cy3- labeled-TTTCCTCCTCCTCCTTCTCCTCCTCCTCC 9012.09 9012.70

8(CR029A)

Z: BzdU Cy3-labeled BzdU-containing GR029A derivatives contained 5-(N- benzylcarboxyamide)-2'-deoxyuridine(BzdU) in Z. CR029A indicated the control form of GR029A, wherein all 'G's in GR029A are substituted with 'C. The GR029A oligonucleotides incorporated with 5-(N-napthylcarboxyamide)-

2'-deoxyuridine(NapdU) instead of BzdU and labeled with Cy3 were also designed (see Table 2), and prepared according to the following synthesis procedure of Example 1.2.

(Table 2) A list of modified GR029A containing Nap at 5 position of dU (5-(JV- naphthylcarboxyamide)-2'-deoxyuridine, NapdU)

Cy3-labeled NapdU-containing GR029A derivatives contained 5-( - napthylcarboxyamide)-2'-deoxyuridine (NapdU) in Z. CR029A indicated the control form of GR029A, wherein all 'G's in GR029A are substituted with 'C. Modified dU-containing AS 1411 derivatives were also designed and synthesized by randomly substituting one to nine thymidine(T) in AS 1411 (GGTGGTGGTGGTTGTGGTGGTGGTGG, SEQ ID NO: 2). Modified dU inserting on AS 1411 is independently selected from 5-(N-benzylcorboxyamide)-2'- deoxyuridine[BzdU] and 5-(7V-naphthylcarboxyamide)-2'-deoxyuridine[NapdU] and 5- (N-4-pyrrimidylbenzylcarboxyamide)-2'-deoxyuridine[4-PBdU]. The modified dU- containing AS 1411 derivatives were summarized in Tables 3-5.

(Table 3) A list of modified AS 1411 having hydrophobic groups such as Bz at 5 position of dU (5-(N-benzylcarboxyamide)-2'-deoxyuridine, BzdU)

Cy3- 1642- 129 Cy3-CCZCCZCCZCCZZCZCCZCCZCCZCC 9171.48 Cy3- 1642- 130 Cy3 -CCZCCZCCZCCTTCTCCZCCZCCZCC 8814.15

Cy3-1642-131 Cy3 -CCTCCTCCTCCZZCZCCTCCTCCTCC 8456.82

Cy3-1642-80

Cy3-GGTGGTGGTGGTTGTGGTGGTGGTGG 8780.0 (AS1411)

Cy3- 1642-81

Cy3-CCTCCTCCTCCTTCTCCTCCTCCTCC 8099.49 (Control AS 141 1)

Z = BzdU

Cy3-labeled BzdU-containing AS1411 derivatives contained 5-(N- benzylcarboxyamide)-2'-deoxyuridine (BzdU) in Z. Control AS 1411 indicated the control form of AS 1411 , wherein all 'G's in AS 1411 are substituted with 'C\.

(Table 4) A list of modified AS 1411 having hydrophobic groups such as Nap at 5 position of dU (5-(N-naphthylcarboxyamide)-2'-deoxyuridine, NapdU)

Comp. No. Cy3-labeled MS

Modified dU-AS1411 sequence

Cy3- 1642- 132 Cy3-GGZGGZGGZGGZZGZGGZGGZGGZGG 10302.53

Cy3- 1642- 133 Cy3-GGZGGZGGZGGTTGTGGZGGZGGZGG 9795.02

Cy3- 1642- 134 Cy3-GGZGGZGGTGGTTGTGGTGGZGGZGG 9456.68

Cy3- 1642- 135 Cy3-GGTGGZGGZGGTTGTGGZGGZGGTGG 9456.68

Cy3- 1642- 136 Cy3 -GGZGGTGGTGGTTGTGGTGGTGGZGG 91 18.34

Cy3- 1642- 137 Cy3 -GGTGGZGGTGGTTGTGGTGGZGGTGG 9118.34

Cy3- 1642- 138 Cy3 -GGTGGTGGZGGTTGTGGZGGTGGTGG 9118.34

Cy3- 1642- 139 Cy3 -GGZGGTGGZGGTTGTGGZGGTGGZGG 9456.68

Cy3- 1642- 140 Cy3-GGTGGTGGTGGTZGTGGTGGTGGTGG 8949.17

Cy3- 1642- 141 Cy3 -GGTGGTGGTGGZZGZGGTGGTGGTGG 9287.51

Cy3- 1642- 142 Cy3-GGTGGTGGTGGZTGZGGTGGTGGTGG 91 18.34

Cy3- 1642- 143 Cy3 -GGZGGTGGTGGTTGTGGTGGTGGTGG 8949.17

Cy3- 1642- 144 Cy3 -GGTGGZGGTGGTTGTGGTGGTGGTGG 8949.17 Cy3-1642-145 Cy3 -GGTGGTGGZGGTTGTGGTGGTGGTGG 8949.17

Cy3-1642-146 Cy3 -GGTGGTGGTGGZTGTGGTGGTGGTGG 8949.17

Cy3-1642-147 Cy3 -GGTGGTGGTGGTZGTGGTGGTGGTGG 8949.17

Cy3- 1642- 148 Cy3 -GGTGGTGGTGGTTGZGGTGGTGGTGG 8949.17

Cy3- 1642- 149 Cy3-GGTGGTGGTGGTTGTGGZGGTGGTGG 8949.17

Cy3- 1642- 150 Cy3 -GGTGGTGGTGGTTGTGGTGGZGGTGG 8949.17

Cy3-1642-151 Cy3 -GGTGGTGGTGGTTGTGGTGGTGGZGG 8949.17

Cy3- 1642- 152 Cy3 -GGTGGTGGTGGTTGTGGTGGZGGZGG 91 18.34

Cy3- 1642- 153 Cy3-GGTGGTGGTGGTTGTGGZGGTGGZGG 91 18.34

Cy3- 1642- 154 Cy3 -GGTGGTGGTGGTTGZGGTGGTGGZGG 91 18.34

Cy3- 1642- 155 Cy3-GGTGGTGGTGGTZGTGGTGGTGGZGG 91 18.34

Cy3- 1642- 156 Cy3 -GGTGGTGGTGGZTGTGGTGGTGGZGG 91 18.34

Cy3-1642-157 Cy3- GGTGGTGGZGGTTGTGGTGGTGGZGG 91 18.34

Cy3-1642-158 Cy3-GGTGGZGGTGGTTGTGGTGGTGGZGG 91 18.34

Cy3-1642-159 Cy3-GGZGGTGGTGGTTGTGGTGGTGGZGG 91 18.34

Cy3-1642- 160 Cy3-GGTGGTGGTGGZZGTGGTGGTGGZGG 9287.51

Cy3-1642-161 Cy3-GGTGGTGGTGGZZGTGGTGGTGGTGG 91 18.34

Cy3- 1642- 162 Cy3 -GGTGGTGGTGGZZGZGGTGGTGGTGG 9287.51

Cy3- 1642- 163 Cy3 -GGTGGTGGTGGZZGTGGZGGTGGTGG 9287.51

Cy3-1642-164 Cy3-GGTGGTGGTGGZZGTGGTGGZGGTGG 9287.51

Cy3- 1642- 165 Cy3-GGTGGTGGZGGZZGTGGTGGTGGTGG 9287.51

Cy3-1642-166 Cy3-GGTGGZGGTGGZZGTGGTGGTGGTGG 9287.51

Cy3- 1642- 167 Cy3-GGZGGTGGTGGZZGTGGTGGTGGTGG 9287.51

Cy3-1642-168 Cy3 -GGTGGTGGZGGTTGZGGTGGTGGTGG 91 18.34

Cy3- 1642- 169 Cy3 -GGTGGZGGTGGTTGTGGZGGTGGTGG 91 18.34

Cy3- 1642- 170 Cy3-GGZGGTGGTGGTTGTGGTGGZGGTGG 91 18.34

Cy3-1642-171 Cy3-GGTGGZGGZGGTTGZGGZGGZGGTGG 9625.85

Cy3- 1642- 172 Cy3-GGZGGZGGZGGTTGZGGZGGTGGZGG 9795.02

Cy3- 1642- 173 Cy3 -ZGGTGGTGGTGGTTGTGGTGGTGGTGGZ 9726.74

Cy3- 1642- 174 Cy3 -CCZCCZCCZCCZZCZCCZCCZCCZCC 9622.02

Cy3- 1642- 175 Cy3-CCZCCZCCZCCTTCTCCZCCZCCZCC 91 14.51

Cy3- 1642- 176 Cy3-CCTCCTCCTCCZZCZCCTCCTCCTCC 8607

Z = NapdU

(Table 5) A list of modified AS 1411 having hydrophobic groups such as 4-PB at position of dU (5-(N-4-pyrrolebenzylcarboxyamide)-2'-deoxyuridine, 4-PBdU)

Cy3-1642-197 Cy3 -GGTGGTGGTGGTTGTGGTGGZGGZGG 9148.28

Cy3- 1642- 198 Cy3-GGTGGTGGTGGTTGTGGZGGTGGZGG 9148.28

Cy3- 1642- 199 Cy3 -GGTGGTGGTGGTTGZGGTGGTGGZGG 9148.28

Cy3- 1642-200 Cy3 -GGTGGTGGTGGTZGTGGTGGTGGZGG 9148.28

Cy3- 1642-201 Cy3 -GGTGGTGGTGGZTGTGGTGGTGGZGG 9148.28

Cy3- 1642-202 Cy3- GGTGGTGGZGGTTGTGGTGGTGGZGG 9148.28

Cy3-1642-203 Cy3 -GGTGGZGGTGGTTGTGGTGGTGGZGG 9148.28

Cy3-1642-204 Cy3 -GGZGGTGGTGGTTGTGGTGGTGGZGG 9148.28

Cy3- 1642-205 Cy3 -GGTGGTGGTGGZZGTGGTGGTGGZGG 9332.42

Cy3- 1642-206 Cy3-GGTGGTGGTGGZZGTGGTGGTGGTGG 9148.28

Cy3- 1642-207 Cy3 -GGTGGTGGTGGZZGZGGTGGTGGTGG 9332.42

Cy3- 1642-208 Cy3 -GGTGGTGGTGGZZGTGGZGGTGGTGG 9332.42

Cy3-1642-209 Cy3 -GGTGGTGGTGGZZGTGGTGGZGGTGG 9332.42

Cy3-1642-210 Cy3-GGTGGTGGZGGZZGTGGTGGTGGTGG 9332.42

Cy3-1642-211 Cy3-GGTGGZGGTGGZZGTGGTGGTGGTGG 9332.42

Cy3- 1642-212 Cy3-GGZGGTGGTGGZZGTGGTGGTGGTGG 9332.42

Cy3- 1642-213 Cy3-GGTGGTGGZGGTTGZGGTGGTGGTGG 9148.28

Cy3-1642-214 Cy3-GGTGGZGGTGGTTGTGGZGGTGGTGG 9148.28

Cy3-1642-215 Cy3 -GGZGGTGGTGGTTGTGGTGGZGGTGG 9148.28

Cy3-1642-216 Cy3-GGTGGZGGZGGTTGZGGZGGZGGTGG 9700.7

Cy3- 1642-217 Cy3 -GGZGGZGGZGGTTGZGGZGGTGGZGG 9884.84

Cy3- 1642-218 Cy3-ZGGTGGTGGTGGTTGTGGTGGTGGTGGZ 9756.68

Cy3- 1642-219 Cy3-CCZCCZCCZCCZZCZCCZCCZCCZCC 9756.75

Cy3- 1642-220 Cy3 -CCZCCZCCZCCTTCTCCZCCZCCZCC 9204.33

Cy3- 1642-221 Cy3-CCTCCTCCTCCZZCZCCTCCTCCTCC 8651.91

Z = 4-PBdU

1.2: Synthesis of Cy3-labled modified dU AS1411 and GR029A

Cy3-labeled AS 1411 (GGTGGTGGTGGTTGTGGTGGTGGTGG, SEQ ID NO: 2) and GR029A(TTTGGTGGTGGTGGTTGTGGTGGTGGTGG, SEQ ID NO: 1), and Cy3-labeled modified dU-containing AS 1411 and GR029A were synthesized using a Mermade 12 DNA synthesizer (BioAutomation Manufacturing, Irging, TX,) with standard solid phase phosphoramidite chemistry. 5-(JV-benzylcarboxyamide)-2'- deoxyuridine (BzdU), 5-(N-naphthylcarboxyamide)-2'-deoxyuridine (NapdU), and 5- (N-4-Pyrrolebenzylcarboxyamide)-2 ' -deoxyuridine(4-PBdU)-phosphoramidite were offered by Samchully Pharmaceutical (Seoul, Korea). All oligonucleotide syntheses were performed in house.

All oligonucleotides were synthesized on functionalized controlled pore glass (CPG) synthesized using a Mermade 12 DNA synthesizer (BioAutomation Manufacturing, Irging, TX) with 0.067 M solution of the modified dU(BzdU, NapdU or 4-PBdU)-amidite in anhydrous acetonitrile. For incorporation of dA, dG, dC and dT residues standard phosphoramidites with excyclic amino groups protected with benzoyl group (for dA and dC) and isobutyryl group (for G) were used. For incorporation of modified dU-amidite, phosphoramidite solution was delivered in two portions, each followed by a 5 min coupling wait time. Oxidation of the internucleotide phosphate to phosphate was carried out using an oxidizer [tetrahydrofuran (THF), pyridine, 0.02 M iodine and water] with waiting time. All other steps in the protocol supplied by the manufacturer were used without modification. The coupling efficiencies were >97%. After completion of the synthesis, the next step is treatment with the cleavage solution(t-butylamine:methanol:water, 1 : 1 :2) at 70 ^°C for 5 hours to hydrolyze the ester linking the DNA to the support and to remove protecting groups from the purine and pyrimidine bases and followed by freezing, filtration, and speed-vac evaporation to dryness.

Crude oligonucleotides were purified by high performance liquid chromatography (AKTA basic HPLC, XBridge OST CI 8 10x50mm, A = 100 mM buffer triethylammoniumbiocarbonate (TEAB), pH = 7, B = acetonitrile, 8% to 40% B in 20 min, flow 5 mL min-1 , at 65 ^°C , 1 = 254 and 290nm). Purified aptamers were precipitated by ethanol and desalted by Centricon (Millipore Bedford, MA). Finally, desalted aptamers were resuspened in water or phosphate buffered saline and sterilized by filtration through a 0.2-μηι syringe filter. Molecular weight and purity of each aptamer was checked by Q-TRAP 2000 ESI-MS spectroscopy (Applied Biosystems foster city, CA) and P/ACE™ 2000 capillary gel electrophoresis(Beckman coulter, fullerton, CA).

Example 2: Affinity of the aptamer to nucleolin

2.1: Cell culture

C6 cells (American type culture collection), which are a rat glioma cell lines, were maintained in DMEM (Gibco, Grand Island, NY) supplemented with 10% fetal bovine serum (FBS, Invitrogen, Grand Island, NY), 10 U/ml penicillin (Invitrogen, Grand Island, NY), and 10 μg/ml streptomycin in a 5% C0₂-humidified chamber at 37 ^°C . The cells were cultured in multiwell chamber slides overnight or 2 days till they reach about 50-80% confluence. After confluent of cells 90-100%, cells were aspirated off media with transfer pipettes and washed with PBS (1 x Phosphate Buffered Saline) briefly. After trypsinization, cells were collected by standard culture media and 1/5 cells that were centrifuged 1000 rpm for 5 min were transferred into T75 flask holding 10 ml media.

2.2: Protein assay

To normalize fluorescence signals of forty-seven Cy3 -labeled BzdU-containing

GR029A and eighteen Cy3-labeled NapdU-containing GR029A compounds, cells treated with each compound were collected with 120 μί PBS buffer after trypsinization and followed with BCA protein assay (Thermo Fisher Scientific Inc. Waltham, MA). Then, the collected cells were moved into 96-microplate well and treated mixture of reagent A and B (1 :50 (v/v)) and incubated at 37°C for 30 min. After the buret reaction, the absorbance at or near 562 nm reader measured on a plate.

2.3: Fluorescence intensity

To determine the targeting efficiency of the cancers, fluorescence intensities of forty-seven Cy3-labeled BzdU-containing GR029A and eighteen Cy3-labeled NapdU- containing GR029A compounds were quantified to evaluate their targeting efficiency at C6 cells by the Varioskan Flash spectral scanning multimode reader (Thermo Fisher Scientific Inc. Waltham, MA; excitation: 535 nm, scanning wavelength: 570 nm with a band width: 12 nm). C6 cells were seeded 1 * 10⁵ cell density onto Magne to FACTION 24 plate (Chemicell, GmbH, Germany) and caring at a 5% C0₂-humidified chamber. After 24 hours of grown, these seeded cells were incubated in DMEM (Dubelocos' modified essential media) with 20 nM of Cy3-labeled GR029A or AS 1411, or 20 nM of each of the Cy3 -labeled modified dU-containing GR029A or AS 1411 compounds at for 30 minute at 4 ^°C for decreasing non-specific binding during 30 min and rinsed by PBS (1 *), then replaced to 200 μΧ Tris buffer, and then treated with each of 47 different compounds (20 pmole). Then, seeded cells was washed with PBS (phosphate buffered saline) two times each for 10 min at RT using shaking incubation (30 rpm) to remove the unbound Cy3-labeled modified dU-containing GR029A or AS 141 1 compounds, and subjected to trypsinization to detach from the plate surface. These cells were collected by PBS (l x) (120 <!) and transferred into 96-well plate (Chemicell, GmbH, Germany) for measurement of fluorescence intensity (100 μί).

The fluorescence intensities of the Cy 3 -labeled modified dU-containing GR029A or AS 141 1 compounds, targeting the nucleolin proteins expressed in the cellular membrane of the C6 cells, were quantified and normalized by units of the cells measured by the Bradford protein assay using Varioskan Flash spectral scanning multimode reader.

2.4: Confocal laser microscopy assay

To further validate the increased binding affinity of modified dU-containing GR029A or AS 1411 by confocal microscopy analysis. Confocal microscopy imaging a laser scanning microscope (Carl Zeiss, Inc., Weimer, Germany; HFT 405/488 nm, DAPI imaging: 420-480 nm, Cy3-labeled compounds: 488/543) was used and each C6 cell was seeded 1 *10⁵ cells onto 12 mm sterile coverslip in 24- well plate. After 24 hr, C6 cells were incubated in PBS for 30 min at 4 °C with Cy3- GR029A or AS1411 , or Cy3-(5-BzdU)-modified GR029A or AS1411 compounds (respectively, 20nM). To remove the unbound conjugates, the cells were washed three times during 10 min using shaking incubation (30 rpm) in PBS (l x) and fixed with 200ul of 3.7 % formaldehyde solution (Sigma, Saint Louis, MO) that was treated 200 βί into cells and incubated at shaking incubation (20 rpm) each for 20 min. After washed three times with PBS for 10 min into shaking incubation, this was followed by staining of the nucleus with a 4',6-diamidino-2-phenylindole dihydrochloride (DAPI; emission: 460 nm, blue color) using the mounting solution (Vector Laboratories, Inc., Burlingame, CA). Fluorescent imaging of targeting C6 cells was visualized by red color. All fluorescence data were acquired at an excitation of 535 nm and emission of 570 nm. The side of fixed cells onto coverslip was put on 10 d of mountain solution (Vector Resources Inc, Torrance, CA. USA). The confocal images were acquired at low magnifications (200x).

2.5: Statistical analysis

Fold ratio of fluorescence activity for 47 different compounds of Cy3 -labeled

BzdU-containing GR029A and eighteen Cy3-labeled NapdU-containing GR029A and the Cy3-labeled CR029A was normalized to the fluorescence signals of Cy3-AS1411 and p-values were calculated using the Student's t-test. 2.6: Results

The results of fluorescence analysis for several Cy3 -labeled BzdU-containing GR029A compounds are shown in Fig. 2. Fig. 2 shows the results of fluorescence analysis of Cy3-labeled BzdU-containing GR029A compounds targeting C6 cells. The fluorescence of the Cy3-labeled BzdU-containing GR029A compounds that were bound and targeted the nucleolin protein in the C6 cells was quantified. The X-axis indicates numbers of compounds. These data are presented as the means ± SD calculated from quadruple wells. All fluorescence data were obtained at an excitation of 488 nm and emission of 543 nm. Fig. 2 presents comparison of the fluorescent intensity of the Cy3-labeled GR029A with excitation at 488 nm and emission at 543 nm, showing that Cy3-labeled BzdU-containing GR029A compounds showed either a slightly or a significantly greater fluorescent activity in the C6 cells compared to Cy3-labeled GR029A or CR029A.

The fold ratio of which the fluorescence signals for 47 different compounds of Cy3-labeled BzdU-containing GR029A was normalized to that of Cy3-labeled GR029A showed that seven different compounds, Compound No. 1642-11, 1642-13, 1642-19, 1642-30, 1642-39, 1642-49, and 1642-51 had about a 1.5 fold or more binding affinity to C6 cells as shown in Fig. 2. In particular, No. 1642-19 compound had approximately 2.5 fold higher fluorescent signals than Cy3-labeled GR029A. The statistical analysis using Student-t test demonstrated that p-value with higher than 0.05 was found in 18 different compounds of Cy3 -labeled BzdU-containing GR029A including No. 1642-19, 1642-39, 1642-49, and 1642-51. This result implied that BzdU modification, such as compounds No. 1642-19, 1642-39, 1642-49, and 1642-51 , significantly increased targeting affinity to C6 cells.

To further validate the increased binding affinity of Cy3-labeled BzdU- containing GR029A by confocal microscopy analysis, compounds No. 1642-19, 1642- 39 and 1642-51 were incubated and visualized in C6 cells with Cy3 -labeled GR029A and Cy3-labeled CR029A (negative control). Twenty 20 nM of each compound was targeted in the C6 cells. The results of confocal microscopy analysis for compounds No. 1642-19, 1642-39, and 1642-51 were shown in Fig. 3. As shown in Fig. 3, comparison of the phase-contrast image and the nuclear DAPI staining revealed that numbers 1642- 19, 1642-39, and 1642-51, and Cy3-labeled GR029A were extensively bound to the plasma membrane of the C6 cells while the Cy3 -labeled CR029A was not clearly visualized in the C6 cells. The targeting affinity to C6 cells, shown in Fig. 3, demonstrated that compounds 1642-19, 1642-39, and 1642-51 had better targeting affinity than did Cy3 -labeled GR029A. The 1642-19 compound showed the highest fluorescent brightness in C6 cells.

To test functional activity of BzdU-containing GR029A, the compounds numbers 1642-39, 1642-51 and 1642-19, in other cancer cells, the inventors first extended cancer targeting assay by selecting another cancer cells, HeLa (human cervix cancer cell line, ATCC), and a normal healthy cell line, CHO (Chinese hamster ovary cell line, ATCC). The measurement of fluorescence intensity was performed as described above for C6 cells. The obtained results are shown in Fig. 4.

Fig. 4 shows the results of fluorescence analysis of numbers 1642-39, 1642-51, 1642-19 and Cy3-labeled GR029A, and Cy3-labeled CR029A (the control form of GR029A labeled with Cy3). Quantitative fluorescence intensity in HeLa and CHO cells. Data are represented as means ± standard error of means (*/?<.05,**Ρ<.005 unpaired t -test). Similar results with C6 cell quantitative fluorescence intensity showed that compounds 1642-39, 1642-51 and 1642-19 had the higher binding affinity for the HeLa cells than the Cy3 -labeled GR029A, while the CR029A had no significant fluorescent signal in HeLa cells. Especially, the 1642-19 compound had approximately a 2.3 -fold higher fluorescent activity in HeLa cells than the Cy3 -labeled GR029A. However, in CHO cells, the compounds including numbers 1642-39, 1642- 51 and 1642-19, Cy3-labeled CR029A, and Cy3-labeled GR029A showed undetectable fluorescence intensity. These results indicate that BzdU-containing GR029A high- specifically targets to cancer cell compared with GR029A.

As shown in Fig. 4, there was no significant difference in binding affinity to CHO cells compared with the mutant. To confirm that the modified GR029A has increased affinity compared to non-modified GR029A other cells than C6, confocal microscopy analyses for HeLa cells and CHO cells were performed as the same method described above. The observed confocal microscopy images in HeLa cells and CHO cells are shown in Fig. 5A (Hela cell) and 5B (CHO cell). Confocal microscopy analysis validated that the compounds numbers 1642-39, 1642-51 and 1642-19 had extensively and better binding affinity to the plasma membrane of the HeLa cells than the Cy3 -labeled GR029A, while the CR029A was not significantly visualized in the HeLa cells. There was no significant difference in binding affinity to CHO cells compared with the mutant. Confocal microscopy analysis validated that the compounds numbers 1642-39, 1642-51 and 1642-19 had extensively and better binding affinity to the plasma membrane of the HeLa cells than the Cy3 -labeled GR029A, while the CR029A was not significantly visualized in the HeLa cells. As expected, the compounds including numbers 1642-39, 1642-51 and 1642-19, CR029A, and GR029A were not clearly visualized in CHO cells.

The results for Cy3 -labeled NapdU-containing GR029A compounds are shown in Fig. 7. Fig. 7 shows the results (fluorescence intensity) measured by fluorescence analysis of Cy3 -labeled NapdU-containing GR029A compounds targeting C6 cells with excitation 488 nm and emission 543nm 4 different compounds. The fluorescence quantification of 18 different Cy3 -labeled NapdU-containing GR029A compounds which were bound and target nucleolin protein in C6 cells. X-axis indicated No. of compounds. These data are presented as means ±SD calculated from quadruple wells. As shown in Fig. 7, compound nos. 1642-70, 1642-71 , 1642-72 and 1642-73 had extensively and better binding affinity to the plasma membrane of the C6 cells than the Cy3-labeled GR029A.

Example 3: FACS (fluorescence activated cell sorter) analysis

3.1: Cell culture

All cultures were grown in a humidified incubator maintained at 37°C with 95% air/5% C0₂. C6 (Glioma cancer), MDA-MB231 (Breast cancer), MG63 (osteosarcoma), U87MG (Glioma cancer), OVCAR-3 (Ovarian carcinoma), and HeLa (Cervical Carcinoma) human cancerous cells were obtained from the American Type Culture Collection (ATCC) and were propagated in DMEM medium supplemented with 10% fetal bovine serum (FBS), penicillin (lOOIUmmL^"1), and streptomycine (lOOIUmmL^"1). AGS (Gastric cancer, ATCC) and HepG2 (Liver cancer, ATCC) cells were grown in RPMI1640 and MEM (Invitrogen, Carlsbad, CA), respectively. NIH3T3 cells (Normal, ATCC) were cultured in DMEM supplemented with 10% FBS and antibiotics (lOOIUmmL^"1 penicillin, lOOIUmmL^"1 streptomycin, Invitrogen, Carlsbad, CA). The modified aptamer was dissolved in culture media before addition to the cell cultures for the cell proliferation assay.

3.2: FACS (fluorescence activated cell sorter) analysis

Cells monolayers were detached by 2mM EDTA, filtered with 40 μπι Cell strainer (BD Falcon), and then washed with HBSS solution (Gibco). The each Cy3- labeled aptamer (AS 1411 or modified dU containing AS1411, lOOpmol) was incubated with cells respectively in 200 μΐ, of HBSS solution on ice for 60 min. Cells were washed three times with 500 μΐ, of HBSS solution and suspended in lmL of 1% paraformaldehyde solution. The fluorescence was determined with FACSCalibur (BD Biosciences) by counting 10,000 events.

The obtained results in various cell lines are shown in Figs 8-21. As shown in Figs 8-21, the intensities corresponding to the peaks for the modified dU-containing aptamer (modified dU containing AS 1411) is higher than those of non-modified aptamer (AS 1411), indicating that the modified aptamer has a higher specificity to cancer cells compared to the non-modified aptamer.

Figs. 22-26 shows the results of quantification of the results of FACS analysis for various cell lines as shown in Figs 8-21, indicating that chemical modification of thymidine at the particular region of AS 1411 with Bz, Nap, or 4-PB, would form more stable G-quardruplex structure via hydrophobic cavities and enhance the potential binding affinity of AS1411 to cancer cells. As shown in Fig. 22-26, Al modified dU- containing AS1411 (GGZGGZGGZGGZZGZGGZGGZGGZGG), a central double modifiddU-containing AS 1411 (GGTGGTGGTGGZZGTGGTGGTGGTGG) and several central double and a more modifieddU-containing AS 1411 (GGTGGTGGTGGZZGTGGTGGTGGZGG,

GGTGGTGGTGGZZGZGGTGGTGGTGG,

GGTGGTGGZGGZZGTGGTGGTGGTGG and GGZGGTGGTGGZZGTGGTGGTGGTGG) increase binding to nucleolin on various cancer cell lines compare to AS 1411.

In particular, both of central double modified dU-containing and a more modified dU-containing AS 1411 have been shown, same or similar binding to various cancer cell lines. The activity between central double modification and a more modification of AS 1411 were measured through the FACS analysis as described above, and the obtained results are shown in Fig. 23. A more modification on any position of central double modified dU-containing AS 1411 was not increased binding to nucleolin on various cancer cell lines, indicating that the modification of the central region (2 bases) may be critical region for the modification of the aptamer to effect on the affinity of the aptamer to nucleolin.

Example 4: MR Imaging

C6 rat glioma cells (ATCC) were cultured in Dulbecco's modified Eagle's medium (Invitrogen), supplemented with 10% heat-inactivated (65 °C for 20 min) fetal bovine serum (Invitrogen) with 1% antibiotics (Invitrogen), in a standard incubator (5% C0₂ atmosphere at 37 °C). 5 <10⁶ cells of the cultured C6 cells were transplanted into subcutaneous tissue of both thigh of nude mice (male, BALB/c, 7-weeks old, Chalsriver).

T2 axial images were obtained using 1.5-T MR imager (GE Medical Systems, Milwaukee, WI, USA) in animal coil box. During the experimentation, the tumor- bearing nude mice were intraperitoneal injections of 50 mL of a ketamine and xylazine (2: 1) solution for anesthesia. The temperature and respirations of the tumor-bearing nude mice were monitored by a rectal thermistor. The sequence parameters for repetitive time (TR) and echo time (TE) were 1400 and 55.8 ms, respectively.

MNP@Si0₂(RITC)-(PEG)/COOH/pro-N/NH₂ nanoparticles (MF, 2 mg/mL) were purchased from Biterials (Seoul, Korea) and prepared as previously described (17). Carboxyl moieties (l . lxl0⁴/nanoparticle) of the MF particles (size; 50nm; hydrodynamic diameter; 58.1 nm) were covalently linked to a 5'-NH₂-modified AS 141 1 aptamer (SEQ ID NO: 2) or the modified dU containing AS 141 1 aptamer using N-(3-dimethylaminopropyl)-N-ethylcarbodiimide (EDC) (MF:aptamer molar ratio in conjugation reaction, 1 :3, Sigma) for 1 h at room temperature. The AS141 1-MF conjugates were washed off by centrifugation at 22,250g for 10 min and resuspended in selection buffer solution (50 mM Tris-HCl, pH 7.4). Amine groups (6.4x10⁴/nanoparticle) protected by the Fmoc group were released by 20% piperidine (Sigma) in an N,N-dimethylformamide solution (Sigma). After 1 h of incubation, the AS141 1-MF particles were washed off twice with Tris buffer (pH 7.4) and briefly sonicated.

The AS1411-MF particle and modified dU containing AS 1411 (central double NapdU-containing AS1411(1642-161))-MF particle were suspended in PBS, and injected into the tumor-bearing nude mice through tail-vein injection in the amount of 5mg/kg of body weight. T2-weighted MR images were obtained from the both thigh of the tumor-bearing nude mice before and 24 hr after intravenous injection of AS 1411- MF or AS1411(1642-161)-MF, and shown in Fig. 27. As shown in Fig. 27, T2- weighed MR images from tumor-bearing mice injected with modified AS1411-MF showed the AS1411-MF particles as bigger block spots than that of AS1411. No T2- negative images were observed in the control AS1411-MF particle-injected tumor- bearing mice.

Example 5: Cell proliferation assay

To test another functional activity of the chemically modified nucleolin aptamer on tumor cell death, cell proliferation test was performed by MTT assay, based on the fact that nucleolin aptamer has antiproliferative effects by specifically binding to the nucleolin transmembrane protein in cancer cells.

To determine cell survival after exposure to the chemically modified aptamer for 5 days, measurement of cell proliferation was preformed colorimetrically by 3-(4,5- dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulphophenyl)-2H-tetrazolium (MTS) assay, using the CellTiter96 Aqueous One Solution Reasgent (Promega). Cells were seeded onto 96-well plates at 4 x 10⁵ cells well^"1 in 100 μΐ_^ of medium, and the tested modified aptamer was added to allow to attach for 24 hr. The cell monolayer was washed with phosphate buffered saline (PBS) to remove unattached cells, and the cells were maintained in serum-free medium (SFM) for 24h, and then washed with PBS. Fresh SFM with the modified aptamer was added, and the cells were incubated for an additional 5 days. Subsequently, the cells were exposed to MTS for 15 min and absorbance was measured using a microplate reader (Dynex Technology, Chantilly, VA, USA) at an optical density (OD) of 490 nm. OD values from the control cells were designated 100% as a standard.

For test the activity CR029A on cell proliferation, 4M of each compound, numbers 1642-39, 1642-51 and 1642-19, Cy3-labeled CR029A, and Cy3-labeled GR029A were added directly to MDA-MB231 cells (Breast cancer, ATCC) and incubated for 1 day. The cell viability(%) was measured based on that of control (100%). The control is a cell group without treatment of aptamer, and the results are shown in Fig. 6.

Fig. 6 shows anti-proliferation effects measured by MTT assay. 4mM of each compounds was treated at 2xl0⁵ C6 cells per well. Data are represented as means ± standard error of means (**P < .005 unpaired t-test). The compounds numbers 1642- 51 and 1642-19 showed significantly higher antiproliferative effect than the Cy3-labeled GR029A, representing 55% and 65% of cell viability.

To confirm that the central double modification of the aptamer is also critical in treating cancer, the effect of central double NapdU-containing AS 1411 (4μΜ) on the viability of MDA-MB231 breast cancer cells (ATCC) were measured by the method as described above, and the results are shown in Fig. 28 (wherein, '6' refers to NapdU). The results indicate that central double NapdU-containing AS 1411 showed higher inhibition effect than AS 1411.

The inventors synthesized various compounds of Cy 3 -labeled modified dU- containing AS 1411 (or GR029A) with single or multiple modifieddUs to increase their binding affinity to nucleolin proteins in the cell membranes of cancer cells. The quantification of fluorescent signals demonstrated that a variety of chemically modified AS 141 1 compounds using modifieddU had varied binding affinity to cancer cells. The number and position of substituents in the AS 1411 (or GR029A) nucleotides were compared with the original sequences of AS141 l(or GR029A). Our statistical analysis and confocal microscopy imaging showed that at least three compounds, numbers 1642- 19 (TTTGGTGGTGGTGGTTGTGGTGGTGGZGG, Z = BzdU), 1642-39 (TTTGGTGGTGGTGGZZGTGGTGGTGGTGG, Z = BzdU), and 1642-51 (ZTZGGTGGTGGTGGZZGTGGTGGTGGTGG, Z = BzdU) out of 47 different Cy3- labeled BzdU-containing GR029A, resulted in a significant increase in targeting the C6 cells. To assess whether the number and position of the BzdU incorporated into GR029A had the influence of targeting and binding the C6 cells, the chemically modified sequences of the 47 different compounds of Cy3 -labeled BzdU-containing GR029A were compared with regard to their fluorescent activity in targeting of the C6 cells. For incorporation of NapdU into GR029A, some central double modification, No. 1642-70(ZTTGGTGGTGGTGGZZGTGGTGGTGGTGG), 1642-71 TZZGGTGGTGGTGGZZGTGGTGGTGGTGG), 1642- 72(ZTZGGTGGTGGTGGZZGTGGTGGTGGTGG) and 1642-

73(ZZGGTGGTGGTGGZZGTGGTGGTGGTGG) had extensively and better binding affinity to the plasma membrane of the C6 cells than the Cy3 -labeled GR029A. There are 12 thymidine nucleotides in the GR029A sequence that can be substituted with modifieddU such as BzdU and NapdU. One fixed incorporation of BzdU at the 12^th thymidine, resulted in the highest binding affinity to the cancer cells and showed increased targeting affinity. In addition, most of the double incorporated BzdU or NapdU at the 7^th and 8^th thymidine, in the GR029A compound, produced either a slight improvement or a significant improvement in the binding affinity for the C6 cells. Other random heavy modification of AS 141 1 did not result in a significant increase in the binding affinity for the C6 cells. These findings imply that chemical modification of thymidines at the central double region of GR029A with modifieddU such as BzdU or NapdU forms a more stable G-quadruplex structure via hydrophobic cavities and enhances the potential binding affinity of GR029A for cancer cells. At the results of FACS analysis with modifieddU-containing AS1411, central double modifieddU- containing AS 1411 (GGTGGTGGTGGZZGTGGTGGTGGTGG, Z = BzdU, NapdU and 4-PBdU) had extensively and better binding affinity to the nucleolin of cancer cell lines than AS 141 1. (see Fig. 29).

FIG. 29 shows a relation between structure and activity of central double modifieddU-containing AS141 1 (or GR029A). The position and structure of chemical modification in central double modification and the original sequence of AS 141 1 were drawn in G-quardruplex structure that normally forms by dimerization of AS 1411 aptamers to bind to nucleolin protein. The results of the examples highlight the fact that chemical modifications can directly applied to alter existing aptamers thereby increasing their binding affinity for targets without a significant increase in time or labor for the SELEX procedure. Such chemically modified aptamers could be used as a valuable clinical tool for identifying serious cancer disease, in a very early stage, and evaluation of cancer therapy. However, further analysis including the study of diverse existing aptamers and their targets as well as study of resistance to enzymatic degradation, biostability in vivo, and optimization of the number and positioning of the modifieddU such as BzdU, NapdU and 4-PBdU compounds in the sequence of the existing aptamers must be studied before in vivo application is considered for the detection and treatment of cancers.

Claims

WHAT IS CLAIMED IS:

1. Nucleolin-specific aptamer, which has the sequence of SEQ ID NO: 3, and one or more thymidines(T) present in the nucleotide sequence are independently substituted with a modified pyrimidine nucleoside, and wherein the modified pyrimidine nucleoside is deoxyuridine(dU), deoxycytidine(dC), uridine(U), or cytidine(C) having a hydrophobic group at 5' position:

NGGTGGTGGTGGTTGTGGTGGTGGTGGN (SEQ ID NO: 3)

wherein each N is absent or 1 to 20 nucleosides, which is independently selected from the group consisting of adenosine(A), thymidine(T)/uridine(U), cytidine(C), and guanosine(G).

2. The nucleolin-specific aptamer according to Claim 1 , which has the sequence of SEQ ID NO: 1 or 2, and one or more thymidines(T) present in the nucleotide sequence are independently substituted with a modified pyrimidine nucleoside, and wherein the modified pyrimidine nucleoside is deoxyuridine(dU), deoxycytidine(dC), uridine(U), or cytidine(C) having a hydrophobic group at 5' position.

3. The nucleolin-specific aptamer according to Claim 1 , wherein the hydrophobic group is selected from the group consisting of a benzyl group, a naphthyl group, or a pyrrolebenzyl group.

4. The nucleolin-specific aptamer according to Claim 1 , wherein the modified pyrimidine nucleoside is selected from the group consisting of 5-(JV- benzylcarboxyamide)-2'-deoxyuridine(called BzdU), 5-(N-naphthylcarboxyamide)-2'- deoxyuridine(called NapdU), 5-(N-4-pyrrolebenzylcarboxyamide)-2'- deoxyuridine(called 4-PBdU), 5-(N-benzylcarboxyamide)-2'-deoxycytidine (called BzdC), 5-(N-naphthylcarboxyamide)-2'-deoxycytidine (called NapdC), 5-(N-4- pyrrolebenzylcarboxyamide)-2'-deoxycytidine (called 4-PBdC), 5-(N- benzylcarboxyamide)-2'-uridine(called BzU), 5-(N-naphthylcarboxyamide)-2'- uridine(called NapU), 5-(N-4-pyrrolebenzylcarboxyamide)-2'-uridine(called 4-PBU), 5- (iV-benzylcarboxyamide)-2'-cytidine (called BzC), 5-(JV-naphthylcarboxyamide)-2'- cytidine (called NapC), and 5-(N-4-pyrrolebenzylcarboxyamide)-2'-cytidine (called 4- PBC).

5. The nucleolin-specific aptamer according to Claim 1 , wherein at least two thymidines present in 9^th to 18^th positions of SEQ ID NO: 3 are substituted with the modified pyrimidine nucleoside, and the positions positions are counted starting from 'G' after 'N' at 5'-end.

6. The nucleolin-specific aptamer according to Claim 2, wherein at least two thymidines present in 12^th to 18^th positions of SEQ ID NO: 1 or 9^th to 18^th positions of SEQ ID NO: 2 are substituted with the modified pyrimidine nucleoside.

7. A composition for diagnosing a cancer, containing the nucleolin- specific aptamer of any one of Claim 1 to Claim 6.

8. The composition according to Claim 7, wherein nucleolin-specific aptamer is labeled by one or more selected from the group consisting of a fluorescence material, infrared material, quantum dots, ion oxide bead, PET probe, Tl MR probe, and T2 MR probe.

9. The composition according to Claim 7, wherein the cancer is selected from the group consisting of leukemias, lymphomas, myeloproliferative disorders, carcinomas of solid tissue, sarcomas, melanomas, adenomas, hypoxic tumors, squamous cell carcinomas of the mouth, throat, larynx, or lung, genitourinary cancers, hematopoietic cancers, head and neck cancers, and nervous system cancers, and benign lesions.

A composition for treating a cancer, containing the nucleolin-specific aptamer of any one of Claim 1 to Claim 6 as an active ingredient.

11. The composition according to Claim 10, wherein the cancer is selected from the group consisting of leukemias, lymphomas, myeloproliferative disorders, carcinomas of solid tissue, sarcomas, melanomas, adenomas, hypoxic tumors, squamous cell carcinomas of the mouth, throat, larynx, or lung, genitourinary cancers, hematopoietic cancers, head and neck cancers, and nervous system cancers, and benign lesions.

12. A composition for inhibiting nucleolin, containing the nucleolin- specific aptamer of any one of Claim 1 to Claim 6 as an active ingredient.

13. A composition for inhibiting hyperproliferation of cell cased by nucleolin, containing the nucleolin-specific aptamer of any one of Claim 1 to Claim 6 as an active ingredient.

14. A pharmaceutical composition containing the nucleolin-specific aptamer of any one of Claim 1 to Claim 6.