WO2010001258A2 - Inhibition of tumour growth and metastases - Google Patents

Abstract

The instant invention relates to compounds of formula 1 and their applications as an anti-cancer agent and/or as an angiogenesis inhibitor in mammals, preferably in humans; the instant invention also includes a method of treatment of metastases of prostate cancers using said compound and also a method of treatment of conditions in which angiogenesis must be inhibited. Said compound of formula 1 wherein R₁ is a C₁-C₆ alkyl group, substituted or not, linear or branched and R₂ represents a halogen atom, is useful for treating solid cancers or preventing metastases of solid cancers, said solid cancers being selected in the group consisting of lung cancer, glioma and prostate cancer.

Description

Inhibition of tumour growth and metastases

The instant invention relates to compounds of formula 1 and their applications as an anti-cancer agent and/or as an angiogenesis inhibitor in mammals, preferably in humans; the instant invention also includes a method of treatment of metastases of prostate cancers using said compound and also a method of treatment of conditions in which angiogenesis must be inhibited. Such conditions may be found in dermatology, ophthalmology, rheumatology, endometriosis and inflammatory diseases. Thus XRP44A may be used to treat cancer and other pathologies associated with the vascular system.

The Inventors have firstly identified a compound, XRP44X, a 3-piperazinylcarbonyl-pyrazole (figure 1) that inhibits the Ras oncogene signalling pathway in in vitro models, including cell lines and ex-vivo organ cultures (47).

More precisely, the Inventors have found in first experiments that XRP44X inhibits fibroblast growth factor 2 (FGF-2)-induced Net phosphorylation by the Ras-Erk signalling upstream from Ras. It also binds to the colchicine-binding site of tubulin, depolymerises microtubules, stimulates cell membrane blebbing, and affects the morphology of the actin skeleton. Interestingly, Combretastin-A4, which produces similar effects on the cytoskeleton, also inhibits FGF-2 Ras-Net signalling. This differs from other classes of agents that target microtubules, which have either little effect (vincristine) or no effect (docetaxel and nocodazole) on the Ras-Net pathway.

As shown in these first experiments, XRP44X inhibits various cellular properties, including cell growth, cell cycle progression, and aortal sprouting, similar to other molecules that bind to the tubulin-colchicine site. XRP44X has the potentially interesting property of connecting two important pathways involved in cell transformation and may thereby represent an interesting class of molecules that could be developed for cancer treatment. In said publication (47), the Inventors provide evidence for a novel pathway for regulation of Ras-MAPK signalling and identify XRP44X, a new molecule that may be useful for the development of cancer therapy. Further to said first experiments, the Inventors have now further on shown that XRP44X inhibits tumour growth and metastases in vivo in animal models, μsing tumour cell lines and nude mice.

In particular, the Inventors have shown that XRP44X inhibits, unexpectedly, human prostate cancer cell metastases more efficiently as combretastatin A4, a different chemical entity.

Unexpectedly, XRP44X inhibits tumour growth when it is used in a preventative or a curative regimen.

In addition, the Inventors have identified gene expression changes induced by XRP44X that can be used to understand the molecular mechanisms of XRP44X activity, and to follow treatment efficacy in the clinic.

Among the major signalling pathways that are deregulated in cancer, the Ras pathway is an attractive target for the development of chemotherapeutic intervention. Human cancers frequently have mutations in components of the Ras pathway, which result in uncontrolled cell growth that is freed from regulation by environmental signals (1-3). Ras links signals emanating from receptor tyrosine kinases signals to downstream effectors, such as Erk-1 and -2 (Erks, extracellular- signal-regulated kinases), that phosphorylate effectors such as transcription factors of the Ets family. Ets proteins are implicated in malignant transformation, and interestingly, ets gene fusions are frequently rearranged in human malignancies (5-7), in particular prostate cancer.

The Inventors have focused on one of the Ets factors that is regulated by Erk phosphorylation, namely Net (also called Elk-3). Indeed, Net is an interesting downstream target of the Ras pathway, which has an important role in physiological and pathological processes, including wound healing, cell migration, angiogenesis (8-11). The Inventors have been developing and using the Net factor as a target for tumour therapy, in particular due to Net's role in angiogenesis (WO 2002/35235). The Inventors have since shown that XRP44X is, unexpectedly, active in animal models of metastasis, using a mouse model of prostate cancer metastasis. Indeed, XRP44X effectively significanly decreases the growth of tumors and the formation of metastases, compared to controls. Further more it inhibits angiogenesis. Thus, the instant invention relates to XRP44X, a 3-piperazinylcarbonyl-pyrazole, having the formula depicted in figure 1, which is a new chemical entity compared to other anti-cancer agents.

New anti-cancer drugs are always needed due to drug resistance which may occur. XRP44X is very interesting due to its distinct mode of action, different from current cancer treatments (microtubule disruption, Ras oncogene pathway inhibition).

In pre-clinical tests in mice, its activity is superior to combretastatin A4 that is currently entering Phase II trials. It is an angiogenesis inhibitor, an area of great current interest in cancer treatment. It targets microtubules, that are already targetted for successful cancer treatment.

Angiogenesis inhibitors have additional applications related to the vasculature associated pathologies.

Another object of the invention is a drug comprising XRP44X and at least a pharmaceutically acceptable vehicle.

A further object of the invention is a method of treatment of solid cancers, which includes the administration to a subject in need thereof of an effective amount of XRP44X.

Another object of the invention is a method of prevention of metastases of solid cancers which includes the administration to a subject in need thereof of an effective amount of XRP44X.

A further object of the invention is a method of inhibiting angiogenesis, which includes the administration to a subject in need thereof of an effective amount of XRP44X. Said cancers are for instance lung cancer, glioma and prostate cancer.

The cancer treatment market is moving towards newer more targeted therapies, which replace less specific treatments or treatments inducing drug resistance. New products will account for around 30% of total drug launches. Prostate cancer is a booming market for new therapies due to 3.4% annual sales growth and the success of docetaxel (TAXOTERE) fuel new therapies. Analysts predict that annual growth will be driven primarily by new entries to the market that will add to, rather than replace, existing therapies. The rapidly increasing older population, too, will certainly increase the need for treatment, since over 75% percent of cases are diagnosed in men over age 65. The average age at the time of diagnosis is 70 and the disease is extremely rare in men under 40. The success of Sanofi-Aventis's Taxotere (docetaxel) in the treatment of hormone-refractory metastatic prostate cancer has fuelled drug developers' interest in novel agents to treat this poor-prognosis population. As a result, drug developers are expected to launch several novel drug classes for prostate cancer treatment including vaccines, angeniogenesis inhibitors, and vitamin D analogues. The Global Market for Angiogenesis Therapeutic Products is projected to reach about US$ 22 billion by 2012. Angiogenesis inhibitors have applications in diseases besides cancer; such as dermatology, ophthalmology, rheumatology, endometriosis and inflammatory diseases. In addition, angiogenesis stimulators have potential in diseases such as cardiovascular disorders including ischemia, congestive heart failure, coronary artery disease, myocardial infarction and peripheral vascular disease and chronic wound care.

XRP44X is a targeted molecule with a defined activity, and hence represents a progression towards targeted therapy moving from a solid base, that includes microtubule poisons such as TAXOTERE. It inhibits prostate cancer metastases. It is an angiogenesis inhibitor, with applications beyond cancer. XRP44X inhibits metastases, a key event for patient survival. More precisely: The invention relates to a compound of formula 1

wherein

Ri is a Ci-C₆ alkyl group, substituted or not, linear or branched and R₂ represents a halogen atom, as a drug for treating solid cancers or preventing metastases of solid cancers, said solid cancers being selected in the group consisting of lung cancer, glioma and prostate cancer.

According to an advantageous embodiment of the invention, said halogen atom is selected in the group consisting of chlorine, fluorine, bromine, and iodine.

According to another advantageous embodiment of the invention, said compound corresponds to 3-piperazinylcarbonyl-pyrazole, wherein R₁ represents a methyl group and R₂ represents a chlorine atom, named XRP44X, as a drug for treating solid cancers or preventing metastases of solid cancers, said solid cancers being selected in the group consisting of lung cancer, glioma and prostate cancer.

The instant invention also relates to a pharmaceutical composition characterized in that it comprises a compound as defined above and at least a pharmaceutically acceptable vehicle. The invention further relates to a compound of formula 1 as defined above as a drug for treating pathologies where angiogenesis is to be inhibited.

According to an advantageous embodiment of the invention, said pathologies are selected among dermatology, ophthalmology, rheumatology, endometriosis and inflammatory diseases. Figure 1. A, structure of full-length Net and its Ras-responsive

COOH terminal activation domain fused to the Gal4 DNA-binding domain (Gal4- Net). B, names, chemical formulas, and structures of piperazinylcarbonyl-pyrazole derivatives isolated in the screens and their regioisomers used as controls.

Figure 2. XRP44X inhibits FGF-2-induced Net phosphorylation (serine 363) in HUVEC. A, kinetics of Net phosphorylation induced by FGF-

2.HUVEC cells were incubated for 4 h in low serum (0.1% FCS), pretreated with

XRP44X (100 nmol/L) or vehicle (DMSO) for 90 min, and then induced with FGF-2

(20 ng/mL) for 0 to 45 min. Conditions: FGF-2 for 0 to 45 min (lanes 2-8 and 15-21), mock-induced with vehicles (lanes 9-13 and 22-26), non induced (lanes 1 and 14; samples taken at the end of the experiment), pretreated with XRP44X (100 nmol/L; lanes 15-26), and mock pretreated (lanes 2-13). Cell extracts were analyzed by

Western blotting for P-Net (MAb2F3) and GAPDH. B and C, changes in overall Net protein expression do not account for differences in P-Net levels. Conditions were as in A, except that PAb2005 was used for Western blotting. D, XRP44X inhibits FGF- 2-induced Net phosphorylation in the nucleus. HUVEC were incubated in low serum for 4 h, pretreated with vehicle (0; top) or XRP44X (100 nmol/L; bottom) for 90 min, treated with FGF-2 for 10 min, and processed for immunocytochemistry using MAb2F3.DAPI stains nuclei. Typical representative fields.

Figure 3. XRP44X inhibits activation of the Ras-Erk-1/2 pathway by FGF-2. A, activation of the Raf-l-Erk-1/2 cascade. HUVEC cells were incubated for 4 h in low serum (0.1% FCS), pretreated with XRP44X (100 nmol/L) or vehicle (DMSO) for 90 min, and then induced with FGF-2 (20 ng/mL) for 0 to 45 min. Extracts were analyzed by Western blotting for phosphorylation of p90Rsk (P-Rsk; Thr³⁵⁹/Ser³⁶³), Erk-1/2 (P-Erk-1/2, Thr²⁰²/Tyr²⁰⁴), Mekl/2 (P-Mekl/2, Ser²¹⁷/²²¹), Raf- 1 (P-Rafl, Ser³³⁸). Total Erk-1/2 and GAPDH were controls. B, Ras activation. To estimate the potential range of conversion of inactive Ras-GDP to active Ras-GTP, extracts from HUVEC growing in complete medium with FCS were loaded with excess GTP-γ-S (lane 1) and GDP (lane 2), and proteins "pulled down" with Raf-RBD beads were analyzed by Western blotting for Ras. To measure the kinetics of Ras activation by FGF-2, HUVEC cells were incubated for 16 h in low serum (0.1% FCS) and induced with FGF-2 (20 ng/mL) for 0 to 15 min (lanes 3-7). To study the effects of XRP44X on Ras activation, HUVEC cells were incubated for 16 h in low serum (0.1% FCS), preincubated with XRP44X or vehicle for 90 min, and induced with FGF-2 (20 ng/mL) for 5 min (lanes 8-10).

Figure 4. Inhibition by XRP44X of aortic microvessel sprouting (A), and inhibition by XRP44X and CA4 of proliferation of cells (B-E) as a function of time (top graphs) and concentration (bottom graphs). A, aorta were implanted in 300 μL Matrigel, overlaid with 1 mL complete medium containing growth factors and serum and incubated for 2 d. The medium was replaced with fresh medium containing vehicle (panels 1 and 6), UO 126 (panels 2, 4, and 7), or XRP44X (panels 3, 5, and 8), as indicated. After 4 d, the cultures were photographed (panels 1-5), washed thrice, incubated for a further 2 d without compounds, and photographed (panels 6-8). B-E, cells were seeded in 96- well plates (2 x 10³ per well), allowed to attach, and, after 12 h, treated with 10 nmol/L of XRPX44X or CA4, and proliferation was measured with the WTS-8 assay every 24 h for 4 d (top graρhs).The effects of different concentrations of the compounds on proliferation were measured after 3 d for HUVEC and NIH3T3 (B, C) and 2 d for HCT-116 and NIH3T3-Ki-Ras (D, E).

Figure 5. XRP44X treatment leads to accumulation of cells in the G2-M phase of the cell cycle and disorganization of the tubulin and actin cytoskeletons. A, NIH3T3 cells were incubated overnight in low serum (0.1% FCS) followed by 24 h in high serum (10% FCS) in the presence of vehicle (control), 50 nmol/L XRP44X, or XRP45X and analyzed by FACS. Similar effects were observed with a range of concentrations of XRP44X (5-500 nmol/L). One representative experiment is shown. B and C, HUVEC cells were incubated for 4 h in 0.1% FCS₃ 90 min with 50 nmol/L XRP44X, 50 nmol/L CA4, or vehicle alone (control) and processed for immunocytochemistry with antibodies against β -tubulin and FITC secondary antibodies, rhodamine-phalloidine to stain F-actin, and DAPI for nuclei. Cells were observed under visible light and by fluorescence microscopy. Representative fields are shown.

Figure 6. Inhibition of Net phosphorylation and the Ras-Erk-1/2 pathway by microtubule inhibitors. A, XRP44X and CA4 inhibit Net phosphorylation, in contrast to docetaxel, vincristine, and nocodazole. HUVEC cells were incubated for 4 h in 0.1% FCS, 90 min with the indicated compounds, and 10 min with 20 ng/mL FGF-2 and analyzed by Western blotting with MAb2F3 to detect P-Net. B, inhibition of Erk-1/2 pathway activation. HUVEC cells were incubated for 4 h in 0.1% FCS, 90 min with 100 nmol/L CA4, docetaxel, or nocodazole, and 0 to 90 min with 20 ng/mL FGF-2. Cell extracts were analyzed by Western blotting with phosphorylated-specific antibodies. C, inhibition of Ras activation. HUVEC cells were incubated for 16 h in low serum (0.1 % FCS), 90 min with 100 nmol/L XRP44X, docetaxel, CA4, or UO 126, and induced with FGF-2 (20 ng/mL) for 5 min. Cell extracts were used directly for Western blotting to detect phosphorylated Erk-1/2 and GAPDH (loading control). The activation state of Ras was determined by "pull down" with RBD beads and Western blotting with a pan-Ras antibody. Figure 7. XRP44X and CA4 inhibit egr-1 and c-fos expression in endothelial cells (HUVEC). HUVEC were seeded at 2.5 x 10⁵ cells per well in 6 well plates, incubated for 24 hours in complete medium, serum and growth factor withdrawn for 14 hours, pretreated for 90 min with vehicle alone, 100 nM XRP44X or CA4, treated with 20 ng/ml FGF-2 for different times and then processed for quantitative RT-PCR (A and B). For dose-response analysis, the concentration of compounds was varied and RNA levels determined 60 min after FGF-2 addition (C- F). RNA was extracted using the Rneasy Micro Kit (Qiagen #74004) with DNAase treatment according to the manufacturer's instructions for different times (A-C) or CA4 (D and E). The RNA was analysed by agarose gel electrophoresis and quantified by OD_2O0- Egr-1 (A, B, E and F) and c-fos (A-D) RNA were quantitated by one step RT-PCR using AMV reverse transcriptase (Roche 11495062001) using a one-step protocol and the LightCycler 480 SYBR Green 1 master kit. The values were adjusted for variations in 28S RNA, used as a control. The experiment was repeated three times, with 2 values per experiment. The average values are shown; the error bars correspond to the error of the mean.

Figure 8. XRP44X inhibits FGF-2 induced Net phosphorylation (serine 363) in mouse and human cell lines. Various cell lines were studied, including NIH3T3 (CI l), mouse fibroblasts, the derived Ki-Ras transformed line NIH3T3- KiRas (DT, C6 rat glioma (ATCC CCL- 107, LL/2 (LLCl) mouse Lewis Lung Carcinoma (ATCC CRL- 1642), SEND skin endothelial cells transformed by polyoma middle T, HCTl 16 human colorectal carcinoma (ATCC CCL-247). (A) Exponentially growing 80% confluent cultures were serum withdrawn (0.05% FCS) for 4 hours, treated with 20 ng/ml FGF-2 for the indicated times, and cell extracts were analyzed by Western blotting with Mab2F3. (B) Cells were pre-incubated with the indicated compounds (30 min C6, LL/2; 60 min SEND, 90 min HUVEC, 180 min NIH3T3), treated with FGF-2 for 10 minutes and cell extracts were analyzed by Western blotting with Mab2F3. (C, D) NIH3T3 (CI l) cells were pre-incubated in low serum (0.05% FCS) in the absence or presence of 100 nM XRP44X (or 1 μM UO 126 not shown), as indicated, and Western blotted for total Net with PAb375 (C). The cells were then treated with FGF-2 for 10 min (D) and analyzed by Western blotting for total Net (Pab375) or P-Net (Mab2F3) (D). Figure 9. XRP44X inhibits FGF-2 induced Net phosphorylation in the nucleus. NIH3T3 (CI l) were incubated in low serum for 4 h, pre-treated with vehicle (0, upper panels), XRP44X (100 nM, middle panels) or XRP45X (100 nM, lower panels) for 180 min, treated with FGF-2 for 10 min, and processed for ICC using MAb2F3. DAPI stains nuclei. Typical representative fields are shown.

Figure 10. XRP44X and CA4 inhibit Ras activation. HUVEC were incubated for 24 hours in complete medium, serum and growth factor withdrawn for 14 hours, treated with 20 ng/ml FGF-2 for different times (A), or pre-treated for 90 min with XRP44X (B) or CA4 (C) before the addition of FGF-2. Cells were processed and Ras-GTP levels were measured with an ELISA assay. The experiment was repeated three times, with duplicates in each experiment. The average values are shown; the error bars correspond to the error of the mean.

Figure 11. XRP44X and CA4 inhibit Net phosphorylation more efficiently than vincristine (Vine), whereas docetaxel (Doc) and nocodazole (Noco) have no effect. NIH3T3 (CI l) cells were incubated for 4 h in 0.05% FCS, 180 min with the indicated compounds, 10 min with 20 ng/ml FGF-2 (+lanes) and analyzed by Western blotting with MAb2F3 to detect phospho-Net (P -Net). Compounds: Lanes 1 :

0; 2: 0; 3: 5 nM; 4: 10 nM; 5: 20 nM; 6: 50 nM; 7: 100 iiM; 8: 1,000 nM; 9: 5,000 nM;

10 0. Small arrows indicate the estimate IC₅₀ values.

Figure 12. Xenographs of highly metastatic cell lines (LLCl Lewis lung carcinoma and C6 glioma) in nude mice for studying the effects of XRP44X on tumour growth and metastasis. XRP44X inhibits FGF2 induced Net phosphorylation

(A). Then tumour growth was followed in the animal (B, C). Initial experiments were performed to establish the treatment protocol (compound solubility, route of injection, regimen, dosage). This led to an initial protocol that inhibited tumour growth using both cell lines. Figure 13. The effects on metastasis were followed by counting metastatic nodules on the lungs after sacrificing the animals. XRP44X inhibited metastasis in three separate experiments.

Figure 14. Xenograft model of experimental bone metastasis. Figure 15. The number of metastases/mouse was inhibited by XRP44X and appears to be superior to CA4.

Figure 16. Detection of metastases by bioluminescence (BLI) 0, 7,

14, 21 and 24 days after treatment with XRP44X. Figure 17. Measurement of body weight.

Figures 18-19. The number of metastases were decreased by about 50% in XRP44X and CA4; however the inhibition is superior with XRP44X.

Figure 20. The tumour burden was decreased by about 80% after 21 days.

Figure 21. Established tumours affected by XRP44X (44).

Figures 22-23. Genes affected by XRP44X. EXAMPLE 1: Materials and Methods

Recombinants. Net, Gal4-N6, Gal4-N5, 8xPal-TK-Luc, Ha-Ras, and pCMV LacZ

(17, 18).

Compound library screen.

The cell-based assays used dual reporter gene read-outs. The test HCTl 16 reporter clone (Ras-Net) expresses Gal4-Net (220-409), GaW UAS-Renilla luciferase, and Ras VaI 12 (to enhance reporter gene expression). The control SW480 cell clone expresses β-catenin that activates firefly luciferase expression from a Tcf/Lef-dependent promoter. The cells in 384-well plates were treated with compounds (500,000) for 24 h before measuring the luciferases.

Transient transfections. NIH3T3 cells were transfected using the calcium phosphate technique; luciferase and control β-galactosidase activities were assayed. Fold activation relative to control vectors was determined in three experiments with two plasmid reparations.

Treatment with compounds and fibroblast growth factor 2. Cells were grown overnight from 80% to 90% confluence, incubated in 0.05% (NIH3T3) or 0.1% (human umbilical vascular endothelial cell, HUVEC) serum for 4 h, treated with compounds for 3 h (NIH3T3) or 1.5 h (HUVEC), 20 ng/mL fibroblast growth factor 2 (FGF-2) for 1 to 90 min, and lysed in Laemmli buffer containing phosphatase and protease inhibitors. Quantitative real-time reverse transcription-PCR.

Total RNA was used. Primers were designed with Oligo 4.0. Amplification specificity was verified by melting curve analysis, and the data were quantified with LightCycler software. The controls for genomic DNA contamination were not reverse transcribed.

Western blotting and antibodies.

Cells were harvested in Laemmli buffer, fractionated by 10% SDS- PAGE, transferred to nitrocellulose membranes, incubated with primary antibodies, horseradish peroxidase-conjugated secondary antibodies, and revealed with SuperSignal Pico West (Pierce).

Ras activation assay.

The Ras activation assay kit (Cytoskeleton, BK008) was used. The controls for loading and signalling pathway activation used cell lysates before affinity chromatography and Western blotting for glyceraldehyde-3 -phosphate dehydrogenase (GAPDH) and phosphorylated Erk-1/2, respectively. Fluorescence-activated cell sorting.

Cells were grown, synchronized in low serum (0.1% for NIH3T3) overnight, treated with compounds for 20 h in medium with serum (10% FCS for NIH3T3), and analyzed by fluorescence-activated cell sorting (FACS) (19) and the CellQuest program (Becton Dickinson). The experiments were repeated at least thrice with 5 to 500 nmol/L of XRP44X.

Mouse aortic ring angiogenesis assay. Thoracic aortas sections (1-mm long) from 8-week-old 129/PAS mice were placed in Matrigel, incubated for 48 h in EGM-2-MV (CC-3202, Clonetics), followed by 3 days in fresh EBM-2-MV containing various compounds. Microvessel sprouts were examined by biomicroscopy and a Cool SNAP camera. The experiments were repeated thrice. Cell proliferation.

Cells (2 x 10³ per well) were seeded in 96-well plates allowed to attach for 12 h. Growth curves were from 10 nmol/L compounds for samples every 24 h. For IC₅₀ values, at logarithmically increasing amounts of compounds, samples were analyzed after 2 (HCT-1 16 and NIH3T3-Ki-Ras) or 3 days (HUVEC and NIH3T3). The WTS-8 cell counting kit was used (Alexis Biochemical). The experiments were repeated thrice, with six wells per condition in each experiment. IC₅₀ values were determined by curve fitting (MatLab) and semilogarithmic plotting. lmmunocytochemistry .

Cells on coverslips were treated with compounds, fixed with acetone/methanol (1:1), and revealed with phosphorylated Net (P-Net) or β-tubulin monoclonal antibodies followed by FITC-conjugated antimouse antibodies. For actin, the cells were fixed with 3.7% formaldehyde, permeabilized with 0.1% Triton X-IOO, and treated with Texas red-conjugated phalloidin. Nuclei were stained with 4', 6- diamidino-2-phenylindole (DAPI; Sigma). EXAMPLE 2: Supplementary Materials and Methods

Cell lines, culture conditions and growth curves The cell lines NIH3T3 (CI l subclone), HCT116-Net-Ras

(transformed with mutated Ki-Ras, Gal-N6, UAS-Firefly-Luciferase reporter; Sanofi- Aventis), HCTl 16 (ATCC CCL-247), HUVEC-C (ATCC CRL-1730), C6 (ATCC CCL- 107) and LLCl (LL/2, ATCC CRL- 1642) were propagated at 37°C with 5% CO₂ in complete medium supplemented with 10% fetal bovine serum (FCS). All cell lines were tested to ensure they were mycoplasma free. For growth curves, cells were seeded in 96 well plates (2 x 10³ per well) in 100 μl, allowed to attach for 24 h, the compounds were added (25 μl in medium) and cell numbers were determined at various times with the Cell Counting Kit-8 (Alexis, CCKi-8, WST-8) following the manufacturer's protocol. Screen of the compound library for leads

The assay format was cell based in 384 well plates (Nunc/Polylabo: reference 164610) using generic dual reporter gene read-outs (FireLite kit, Packard, ref 6016939). The test reporter cell line (Ras-Net) was isolated by co-transfecting 3 plasmids in the human colon carcinoma HCTl 16 cell line: pCDNA3 Gal4-Net (220- 409) (Neomycin resistance), Gal4 (5xUAS-Gal4 binding site)-Renilla Luciferase (Zeocyn resistance) and pSV2 (SV40) Ras VaI 12 (Hygromycin resistance). Ras VaI 12 expression enhanced reporter gene expression, as expected from activation of the Net C-terminal activation domain by the Ras-ERK pathway.

The control cell line, which was used to exclude molecules that had non-specific effects on reporter activity, is a SW480 colon carcinoma clone that expresses a high level of β-catenin protein and contains a Firefly luciferase reporter gene under the control of a Tcf/Lef dependent promoter. The Ras-Net line was cultured in Medium C (D-MEM without phenol red + 10% FCS + 1% glutamax + 1% penicillin-streptomycin + 0.1% phenol red + 25μg/ml Zeocin + 200μg/ml hygromycine + 400μg/ml geneticin) and the β-catenin cell line in Medium B (D- MEM without phenol red + 10% FCS + 1% glutamax + 1% penicillin-streptomycin + 0.1% phenol red + lOOμg/ml zeocin). The assay protocol consisted of:

(1) Plating 10⁵ cells of each type per 50 μl of medium A (D-MEM without phenol red + 10% FCS, + 1% glutamax, + 1% penicillin-streptomycin) in 384 well plates and incubating the plates at 37°C, 5% CO₂, 90% humidity during 18h;

(2) adding 10 μl of diluted compounds (500,000) in medium D (25% D-MEM without phenol red + 74% H₂O +1% penicillins-treptomycin), incubating at

37°C, 5% CO₂, 90% humidity for 24h;

(3) adding 30 μl of LucLite reagent, incubating at room temperature for 15 min to 2h30 and measuring the Firefly luciferase luminescence signal (β- catenin signal); adding 15 μl of RenLite reagent (between 30 min and 4 hours after the addition of Luclite reagent) and incubating at room temperature for 40 to 60 min and measuring the Renilla luciferase luminescence signal (Net signal). Transient transfections and luciferase assays

NIH3T3 cells were seeded 2-3 h prior to transfection in 6 well plates at 5 x 10⁵ cells /well and transfected using the calcium phosphate technique as previously described (18) with 2 μg pTL2Net, 0.5 μg pRasCTBx2 (Ras-V12), 1 μg 8xPal-TK-Luc, lμg pCMV LacZ.

After removal of the precipitate, the cells were incubated in medium containing 0.05% FCS for 26 h. The cells were scraped into 150 μl of lysis buffer (25 mM Tris-HCl pH 7.8, 1 mM DTT, 2 mM EDTA, 10% glycerol and 0.5% Triton X- 100). The lysates were spun for 5 min, and the supernatants assayed for luciferase and β-galactosidase activity. Luciferase activities, from three experiments with two plasmid preparations, were corrected for β-galactosidase activity expressed from the internal control and used to calculate fold activation relative to control vectors. For the HCT1 16-Net-Ras clone, the Promega Renilla Luciferase Assay System (E2810) was used and a Luminometer (EG&G Berthold). At least two independently prepared DNAs were tested. Each experiment was performed at least three times, in duplicate. Luciferase activity was corrected for transfection efficiency using β- galactosidase activity as a control.

Treatment with compounds andFGF-2

Cells were seeded and grown overnight to reach 80-90% confluence, washed twice with DMEM, incubated in medium containing 0.05% (NIH3T3) or 0.1% (HUVEC) serum for 4 h (to diminish signal transduction events induced by high serum), and then treated without medium change with the indicated compounds for 3 h (NIH3T3) or 1.5 h (HUVEC). Signal transduction was induced with 20 ng/ml FGF- 2 (R&D Systems, Mineapolis, MN) for 1-90 min. Cells were washed twice with cold PBS and scraped directly into Laemmli loading buffer containing 1 mM orthovanadate, 1 mM NaF, protease inhibitors and 0.1 mM PMSF (200 μl per well of 6 well plates). Compounds: XRP44X, XRP45X, XRP57X, XRP58X, combretastatin- A4, nocodazole, vincristine and docetaxel (Sanofi-Aventis), UO 126 (Promega), PD98059 (Alexis), SB203580 (Alexis). Quantitative real-time RT-PCR

Total RNA was prepared using RNAsolv (Omega Bio-tek) and verified on 1% agarose gels. Quantitative real-time RT-PCR was performed using the LightCycler and SYBR Green I (Roche Diagnostics). Primers for egr-J, c-fos and the internal control 28S RNA were designed using the Oligo 4.0 program. The reactions, containing 250 and 500 ng of RNA, and Ix master mix [0.5 μM primers, 4 mM MgCl₂, 200 μM dNTPs, Ix PCR buffer, 1 unit/μl Superscript reverse transcriptase (Invitrogen), Taq polymerase (Promega), anti-Taq antibody diluted 1/200 (Taqstart antibody; Clontech), 4.3% glycerol, 0.15 mg/ml BSA and 0.25x SYBR green I], were reverse transcribed for 10 min at 55°C, denatured for 30 sec at 95⁰C and cycled 40 times for 2 sec at 95°C, 10 sec at 60°C and 15 sec at 72⁰C. Amplification specificity was verified by melting curve analysis, and the data quantified with LightCycler software. Genomic DNA contamination controls were performed by repeating the procedure on the same samples without reverse transcriptase - no amplification was observed. The following primers were used:

Mouse egr-1 :

ACG46 (5'-GCCGAGCGAACAACCCTA-S') (SEQ ID NO: 1) and ACG47 (5' -TCCACCATCGCCTTCTCATT-S'); (SEQ ID NO:2)

Mouse c-fos:

ACG44 (5'AAGGGAACGGAATAAGATGGC-S ') (SEQ ID NO:3) and ACG45 (5'-CAACGCAGACTTCTCATCTTCAA-S'); (SEQ ID NO:4) Human c-fos (Qiagen, QT00007070) Human egr-1:

BAH788 (5ΑGCAGCAGCACCTTCAACC-3') (SEQ ID NO:5) and BAH789 (5'-TCCACCAGCACCTTCTCGT-S '), (SEQ ID NO:6) 28S RNA:

ACD229 (5'-GGCGGCCAAGCGTTCATAGC-S') (SEQ ID NO:7) and ACD230 (5'ATTTGGTGTATGTGCTTGGC-S') (SEQ ID NO:8). Western blotting, antibodies Cells were harvested in Laemmli buffer, fractionated by 10% SDS- PAGE, transferred to nitrocellulose membranes that were then blocked [1 h in TBS-T (TBS-0.1% Tween 20) - 3% Regilait milk powder), rinsed (3 times with TBS-T), incubated with primary antibodies (1/1000 or 1/2000 in TBS-T-5% chicken ovalbumin) overnight at 4°C, washed with TBS-T, incubated with HRP conjugated secondary antibodies (1/5000 in TBS-T) for 1 h at room temperature (RT), washed 3 times with TBS-T, and revealed with SuperSignal Pico West (Pierce, Rockford, II). Antibodies: MAb2F3 [Phospho-Net (21)], PAb2005 [raised against the human Elk-3 sequence CHMPVPIPSLDRAASPVLLSSNSQKS (SEQ ID NO:9) (Peptide PG 173) in rabbits], P-Rsk [Phospho-p90RSK (Thr³⁵⁹/Ser³⁶³), Cell Signalling #9344], PERK- 1/2 [Phospho-p44/42 MAP Kinase (Thr²⁰²/Tyr²⁰⁴) Ab, Cell Signalling #9101], ERK1/2 (p44/42 MAP kinase, Cell Signalling #9102], P-Mekl/2 [Phospho-Mekl/2 (Ser²¹⁷/²²¹) Cell Signalling #9121)], P-Raf-1 [Phospho-c-Raf (Ser³³⁸) (56A6), Cell Signalling #9427], GAPDH (MAB374 Chemicon International), TBP (IGBMC, core facility), β-tubulin (Sigma, Clone Tub 2.1, T 4026). Ras activation assay The activation state of Ras was measured with pull-down and

ELISA assays. For the pulldown assay, the Ras Activation Assay Kit (Cytoskeleton, BK008) was used according to the manufacturer's protocol. 80% confluent HUVEC in 14 cm tissue culture plates were serum starved for 24 h, treated with compounds and FGF-2 as described above, and processed. Ras-GTP from cell lysates (2 mg per point quantified by Bradford) was "pulled down" with Rafl-RBD (Ras binding domain) beads and detected by 12% SDS-PAGE and Western blotting using anti-Ras antibody. Loading and signaling pathway activation were controlled using cell lysates (before affinity chromatography) and Western blotting for GAPDH and P-ERK-I /2, respectively. The experimental procedures for the assay are described in detail in the manufacturer's protocol guidebook http://www.cytoskeleton.com/products/biochem/bk008.html. For the ELISA assay, HUVEC were seeded at 2.5 x 10⁵ cells per well in 6 well plates, incubated for 24 hours in complete medium, serum and growth factor withdrawn for 14 hours, treated with 20 ng/ml FGF-2 for different times, or pre- treated for 90 min with XRP44X or CA4 before the addition of FGF-2. Cells were processed and Ras-GTP levels were measured with the Ras GTPase Chemi ELISA Kit (Active Motif #52097) according to the manufacturer's instructions. The experiment was repeated three times, with duplicates in each experiment. FACS

Cells were grown on 9 cm cell culture dishes, synchronized by incubation in low serum (0.1% for NIH3T3) overnight and treated with the compounds for 20 h in medium with serum (10% FCS for NIH3T3). Cells were processed for FACS analysis as described previously (19) and the flow cytometry data was analyzed with the CellQuest program (Becton Dickinson, San Jose,. CA, USA). The experiments were repeated at least three times with a range of concentrations of XRP44X (5-500 nM) and different cell lines. Mouse Aortic Ring angiogenesis assay

Thoracic aortas were excised from 8-week-old 129/PAS mice, washed, cut into 1-mm-long sections, and placed upright in 300 μl of Matrigel (Becton Dickinson Labware) that was allowed to solidify for 30 min (Nicosia & Ottinetti, 1990; Rohan et al., 2000). The sections were incubated for 48 h in EGM-2- MV (CC-3202, Clonetics) followed by 3 days in fresh EBM-2-MV containing various compounds. The microvessel sprouts were examined at various times by biomicroscopy and photographed with a Cool SNAP camera. The experiments were repeated three times.

Immunocytochemistry

Cells were grown on cover slips and treated with compounds as described above. To detect P-Net and β-tubulin, the cells were fixed with acetone/methanol (1/1) for 10 min at -20°C and rehydrated with TBS, blocked with 3% BSA in TBS for 30 min at RT, incubated with monoclonal antibodies raised against P-Net (MAb2F3; 1/1000 in 0.5% BSA in TBS-T) or βtubulin (Sigma; 1/500 in 0.5% BSA in PBS) for 2 h at 37°C in a humid chamber, washed in TBS, and incubated for 1 h at 37°C with FITC-conjugated anti-mouse antibody (Jackson). For actin cytoskeleton staining, the cells were fixed with 3.7% formaldehyde in TBS for 10 min at RT, permeabilised with 0.1% Triton X-100 for 5 min, washed 3 times with TBS, treated with Texas red conjugated phalloidin (Molecular Probes; 1/40 in PBS) for 20 min at RT and washed 3 times. To label nuclei, the cells were stained for 1 min at RT with DAPI (Sigma), washed 3 times, mounted on slides with 5% propylgallate and 80% glycerol in PBS, and observed with a fluorescence microscope. EXAMPLE 3: A high throughput cell-based screen for inhibitors of Ras-induced transcription activation.

To identify small molecules that inhibit Ras onco gene-induced Net transcription activation, a HCTl 16 reporter cell line was established (HCTl 16-Net- Ras). It expresses two proteins, oncogenic Ha-Ras and the Net-Ras responsive transcription activation domain (215-409) fused to the Gal4 DNA-binding domain (Gal4-N5; Fig. IA), and in addition, it contains a Gal4 UAS-Renilla luciferase reporter. A counterscreening SW480 cell line was produced containing the Firefly luciferase gene under the control of a β-catenin/T-cell factor promoter sequence (data not shown). A library of small molecules was screened, resulting in the identification of XRP44X, a 3-piperazinylcarbonyl-pyrazole (Fig. IB) that inhibited Ras-induced transcription activation (IC₅₀, 10 ± 6.5 nmol/L; Table I) with little effect on the β- catenin/T-cell factor-dependent transcription activation (IC₅0, >3,000 nmol/L). The properties of XRP44X were studied in comparison with its regioisomer XRP45X and with the related molecule XRP57X and its regioisomer XRP58X. The effects of these compounds on Net activity were investigated using the HCT116-Net-Ras reporter cell line (Table I). XRP44X inhibited luciferase activity more efficiently than its regioisomer XRP45X (IC50, ~ 10 and 700 nmol/L, respectively), the related molecule XRP57X (IC_5O, ~ 80 nmol/L), and its regioisomer XRP58X (IC₅₀, ~ 1,500 nmol/L). These values were determined from dose-response curves and reflect true differences rather than "plateau effects". The effects were not merely due to general cytotoxicity, because there was no significant variation in the total protein concentration extracted from the cultures and the compounds had no effect on the β-catenin/T-cell factor-responsive cell line. To test the effect of XRP44X on the activity of full-length Net, transfection experiments in NIH3T3 fibroblasts were used. A Ras-responsive reporter (Palx8-TK-Luc; ref. 17) was cotransfected with expression vectors for Net, Ha-Ras-Vall2 to activate Net, and β-galactosidase as an internal control. XRP44X inhibited Net activity to a greater extent than the other compounds (Table I). The Erk-1/2 pathway inhibitor U0126, which inhibits Net phosphorylation and activation (10), also decreased luciferase activity. General toxicity could not account for the effects of the compounds because there was no significant variation in β-galactosidase activity. These results indicate that XRP44X inhibits Ras-induced activation of Net efficiently and specifically.

Table I. Effects of compounds on Gal4-N6 activity in HCTl 16-Net-Ras cells, and Net activity in NIH3T3 cells.

(A) HCTl 16-Net-Ras cells were treated with the indicated compounds for 24 h, Renilla luciferase activity was measured, and IC₅₀ values were determined. (B) NIH3T3 were transfected by the calcium phosphate technique as described in the Materials and Methods, the cells were washed to remove the precipitate, and after 2 h treated with the indicated compounds in low serum for 24 h. The average and standard deviation of the corrected inhibition of luciferase activity (Inh%) for three experiments is shown. EXAMPLE 5: XRP44X inhibits Net phosphorylation.

Growth factors stimulate the Ras-Erk-TCF pathway rapidly and transiently, leading to changes in gene expression (20). The Inventors investigated the effect of XRP44X on FGF-2 induction of the endogenous c-fos and egr-1 genes by quantitative real-time reverse transcription-PCR. Mouse fibroblasts (NIH3T3 cells) were pretreated for 3 h with 100 nmol/L XRP44X, treated with FGF-2 for 40 min, and analyzed for c-fos and egr-1 RNA expression. XRP44X inhibited expression of both genes by ~ 65% (Table II).

Table II. Effects of compounds on Net target gene induction by FGF-2 in NIH3T3 cells.

NIH3T3 were incubated overnight in low serum, treated for 3 h with 100 nM of the compounds, induced with FGF-2 for 40 min and total RNA was analyzed by quantitative real time RT-PCR. The values were normalized to the control cells without compounds, and percentage of inhibition (Inh %) of either gene expression for the average of 3 experiments and the standard deviations are given.

HUVECs were studied more extensively (Fig. 7) to determine the effects on the time course (A and B) and the dose dependency (C and D). Fifty percent inhibition of egr-1 and 65% of c-fos were observed with 200 nmol/L XRP44X 60 min after FGF-2 induction (C and D). The extent of inhibition was similar after 30 min (A and B). There were no significant variations in 28S RNA levels, showing that the decrease was not due to nonspecific effects. Taken together, these results indicate that the 3-piperazinylcarbonyl-pyrazole XRP44X inhibits transcription activation induced by the growth factor-Ras-Net pathway. Because c-fos and egr-1 are Net target genes and Net is activated by Erk phosphorylation, the Inventors investigated whether inhibition resulted from effects on Net phosphorylation. Growth factors stimulate phosphorylation of the COOH terminal domain of Net through the Ras-Erk pathway. Phosphorylation of Ser , which is one of the most important phosphorylation sites for activation of the COOH terminal domain, was followed using the MAb2F3 phosphorylated-specific antibody (10, 21). Normal HUVEC were serum starved for 24 h and treated with 20 ng/mL FGF-2 and Net phosphorylation, followed by Western blotting with the phosphorylated-specific antibody (Fig. 2A). Net phosphorylation was detected after 5 min (lane 4), was maximal after 10 min (lane 5), and gradually declined up to 45 min (lane 8). There was a shift in mobility of Net that could be correlated with the intensity of the bands, as might be expected from the phosphorylation of several sites on Net (10, 21). Changes in intensity of the bands were reproducibly observed in HUVEC and other cell lines (NIH3T3 mouse fibroblasts, C6 rat glioma, LL/2 mouse Lewis lung carcinoma, SEND skin endothelial cells transformed with polyoma middle T and HCTl 16 colon carcinoma cells, but not NIH3T3-Ki-Ras and PC3 prostate carcinoma cells (Fig. 8 and data not shown), whereas the shift was more variable and depended on the cell line used, the particular conditions of electrophoresis and the initial state of phosphorylation of Net (Fig. 8A and data not shown). Similar to Net, the related protein EIk-I has been extensively characterized and shown to have several phosphorylation sites of varying importance for transcription activation (22). In some experiments, the 2F3 phosphorylated- specific antibody detects additional nonidentified bands in HUVEC cells (Fig. 2; see also Fig. 8 A and B). The identities of these bands are not known and could correspond to other modified forms of Net or other proteins. They do not compromise the identification of the P-Net bands nor the interpretations of the experiments, which have been repeated a large number of times in HUVEC and in a number of other cell lines. To investigate whether the compound inhibited Net phosphorylation, HUVEC cells were pretreated with 100 nmol/L XRP44X for 90 min and then treated with FGF- 2. XRP44X clearly inhibited Net phosphorylation by ~ 80%, without affecting the kinetics of the residual phosphorylation that could still be detected (Fig. 2 A, lanes 17— 21). XRP44X treatment alone did not induce Net phosphorylation (lanes 22-26).

The total levels of Net, detected with an antibody raised against the COOH terminal region of Net (polyclonal antibody 2005), did not significantly change during the course of the experiment (Fig. 2B, lanes 1-12; data not shown). There was a shift in the mobility (Fig. 2C, lanes 1-12) that coincided with the shift observed with the phosphorylated-specific antibody and probably reflects the effect of phosphorylation on migration once FGF-2 is added to the cells. The levels of the loading control GAPDH remained constant (Fig. 2A, lanes 1-26). Inhibition of Net phosphorylation was observed with a range of concentrations of XRP44X (20 nmol/L- 5 μmol/L; data not shown). XRP44X was also found to inhibit Net phosphorylation in other cell lines, including NIH3T3 fibroblasts, C6 glioma cells, LL/2, and SEND (Fig. 8). In NIH3T3 cells, preincubation in the absence or presence of XRP44X for up to 180 min did not affect the levels of Net protein (polyclonal antibody 375; Supplementary Fig. 8C, lanes 1-12). Similarly, preincubation with the Mek inhibitor UO 126 inhibited Net phosphorylation without affecting total Net protein (Fig. 8D, lanes 1-4). XRP45X, XRP57X, and XRP58X were considerably less efficient than XRP44X in inhibition of Net phosphorylation induced by FGF-2 (Fig. 8B₃ lanes 5- 10). These results show that XRP44X inhibits Net prosphorylation without altering total protein levels. Net phosphorylation was also evaluated by immunocytochemistry of HUVEC with MAb2F3 (Fig. 2D). FGF-2 treatment for 10 min led to a clearly detectable increase in P-Net in cell nuclei. This staining was more intense than in cells pretreated for 90 min with XRP44X. The remaining detectable P-Net in XRP44X- treated cells was still mainly located in the nucleus. Similar results were obtained in NIH3T3 cells (Fig. 9). The results from Western blotting and immunocytochemistry show that XRP44X inhibits Net phosphorylation on Ser³⁶³ in the nuclei of cells. EXAMPLE 6: XRP44X inhibits FGF-2 activation of the Erk-1/2 pathway.

The Inventors have previously shown that FGF-2 stimulates Net phosphorylation through the Erk-1/2 pathway (10), raising the possibility that XRP44X inhibits this signaling cascade. Erk-1/2 activation involves formation of Ras- GTP, Raf recruitment, sequential phosphorylation, activation of Raf-1, Mek- 1/2, and Erk-1/2, and finally phosphorylation by Erk-1/2 substrates, such as Rsk (23), as well as Net. They tested whether XRP44X affects this cascade. XRP44X inhibited phosphorylation of Rsk- 1 (Fig. 3A), showing that XRP44X is not a specific inhibitor of Net phosphorylation. XRP44X inhibited phosphorylation of Erk-1/2 on sites required for its activation without affecting overall levels of Erk-1/2 (Fig. 3A). Furthermore, it inhibited phosphorylation of Mek- 1/2 and Raf-1 (Fig. 3A) and activation of Ras (Fig. 3B; see also Fig. 6C). Because the observation that XRP44X inhibits Ras activation is important, they also measured Ras activation with an ELISA-based assay. In time course experiments, maximum Ras activation was observed after 5 min (Fig. 10), in agreement with the pulldown assays (Fig. 3B). In dose-response experiments, maximum inhibition was observed with 100 nmol/L XRP44X. These results show that XRP44X is an indirect inhibitor of Net phosphorylation that acts upstream from Erk-1/2 activation. This is not necessarily unexpected, considering that a cell-based screen and a functional readout were used to isolate XRP44X.

EXAMPLE 7; XRP44X inhibits microvessel sprouting from aorta in organ cultures and cell growth.

The mechanisms by which XRP44X inhibits the Ras-Erk pathway was investigated further using a variety of assays that led to insights into its activities. One of these approaches was to study cellular processes that are regulated by Net, including microvessel sprouting from aorta in organ culture and cell growth (10). In the aorta ring assay (Fig. 4A), XRP44X inhibited microvessel sprouting when the aorta were incubated with 5 nmol/L of XRP44X for 3 days (compare panels 1 and 3). The inhibition was greater when 50 nmol/L of XRP44X was used (panel 5). To study regrowth after removal of the inhibitor, XRP44X was soaked out of the semisolid medium by washing and adding fresh medium lacking XRP44X to the 50 nmol/L XRP44X cultures. Microvessel sprouting was clearly restimulated (panel 8), showing that regrowth was possible when the concentration of XRP44X was decreased. Inhibition of aortic sprouting by XRP44X was observed in three different experiments with three aorta cultures per treatment and 5, 10, 20, and 50 nmol/L XRP44X (data not shown). As a positive control, the mitogen-activated protein/ERK kinase 1/2 inhibitor UO 126 was shown to inhibit microvessel sprouting (panels 2 and 4), and washing out the inhibitor restored growth (compare panel 7 with panel 6), as expected from the known role of Erk-1/2 signalling in aortic sprouting (24). The effect of XRP44X on the growth of endothelial cells (HUVEC) was followed with a modified 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (WTS-8). XRP44X inhibited their growth (Fig. 4B), with an IC₅₀ of- 2 nmol/L (Table III). Table III. Anti-proliferative activity of XRP44 and CA4.

Cells were seeded at 2 x TO³ cells per well in 96 well plates, allowed to attach for 12 hours before treatment with vehicle (0.1% DMSO), different compounds, or no addition. Logarithmically increasing amounts of compounds were added (Fig 4B-E)₅ and cells were counted after 2 (HCT-116 and NIH3T3-KiRas) or 3 days (HUVEC and NIH3T3). The WTS-8 cell counting kit was used according to the manufacturer's instructions (Alexis Biochemical). The experiments were repeated 3 times, with 6 wells per condition and experiment. IC₅₀ values were determined by curve fitting (MatLab) and semi-logarithmic plotting.

XRP44X also inhibited the growth of immortalized mouse fibroblasts (Fig. 4C), the human tumor cell line used to develop the HTS target cell line (HCT-116; Fig. 4D), and the Ki-Ras transformed cell line derived from the NIH3T3 cell line clone shown (Fig. 4E). The IC₅₀ values for the endothelial cells, the human tumor cell line, and the transformed fibroblast line were similar. The nontransformed fibroblasts used for Ki-Ras transformation had a slightly higher IC₅₀ (Table III), indicating that Ki-Ras transformation might increase the sensitivity to XRP44X. The antiproliferative activity of XRP44X relative to the related compounds (XRP45X, XRP57X, and XRP58X) was measured with a thymidine incorporation assay on various cell lines derived from the most common human tumors. XRP44X inhibited proliferation more efficiently than its regioisomer XRP45X, and the related molecule XRP57X and its regioisomer XRP58X (Table IV). These results show that XRP44X specifically inhibits growth of cells derived from many common human tumors.

Table IV. Anti -proliferative activity of XRP44X and related compounds on tumor cell lines.

Cell lines were grown at 37°C under 5% CO₂ atmosphere in RPMI 1640 medium containing 10 μM 2-mercaptoethanol, 2 mM L-glutamin, 200 UI/ml penicillin, 200 μg/ml streptomycin and 10% (V /V) calf fetal serum. Cells were seeded at 2 - 10,000 cells/well in 0.17 ml in 96 well Cytostar microplates (Amersham). 20 μl of compound to be tested and 10 μl of Thymidine [methyl-14C] (100 μCi/ml - NEN Technologies) were then added and incubated at 37°C under 5% CO2 atmosphere. In each experiment, compounds were tested at various concentrations in quadruplicate. After 48 h incubation time, incorporated ⁴C-thymidine was counted in a 1450 Microbeta Wallac Trilux liquid scintillation and luminescence counter. EXAMPLE 8: XRP44X leads to G2-M cell cycle arrest and alters the tubulin and actin cytoskeletons.

The mechanisms by which XRP44X affects cell growth were examined further using cell cycle analysis, visual inspection, and immunocytochemistry in various cell types, especially NIH3T3 fibroblasts and HUVEC endothelial cells. For FACS analysis, NIH3T3 cells were synchronized by incubation overnight in medium containing 0.1% FCS. They were then incubated in high serum (10% FCS) in the presence of vehicle (control), 50 nmol/L XRP44X, or XRP45X. The treatment with XRP44X resulted in the accumulation of cells in the G₂- M phase in comparison with XRP45X or control (Fig. 5A), which is compatible with the observed inhibition of cell growth (see above; similar results were obtained with HUVEC and several other cell lines; data not shown). Cells were visually inspected by phase contrast microscopy. HUVEC were incubated in the conditions used to analyze signal transduction (see above), namely 4 h in low serum followed by 90 min with 50 nmol/L XRP44X or XRP45X, fixed, and observed under the microscope (Fig. 5B, visible). XRP44X was found to induce "blebbing" of the cell surface in contrast to XRP45X (data not shown) or vehicle control. Similar effects were observed with NIH3T3 and other cell lines data not shown). These changes are reminiscent of CA4, which has effects on both tubulin microtubules and the actin cytoskeleton (25-27). Immunocytochemistry was used to examine microtubules using antibodies against β- tubulin. Treatment of HUVEC cells with XRP44X led to disorganization of the tubulin microtubules in contrast to XRP45X (data not shown) and the control (Fig. 5B). This effect of XRP44X is similar to the effects already described for CA4 (25- 27) and reproduced in Fig. 5B ; however, the effect of XRP44X is superior to the effect of CA4. The Inventors then compared the effects of XRP44X and CA4 on Filamentous actin (F-actin) using rhodamine-phalloidine (Fig. 5C). Both compounds had similar effects on the actin cytoskeleton, leading to the formation of actin-lined cell surface protrusions (blebs). Similar effects on the actin cytoskeleton were observed in NIH3T3 (data not shown). Using FACS analysis, they also confirmed that CA4 blocked cells in the G₂-M phase, similar to XRP44X (data not shown). CA4 binds to the colchicine site and depolymerizes microtubules (27). They showed that XRP44X binds to the same site as CA4 on tubulin and also depolymerizes microtubules (Table V). They also showed that CA4 inhibits proliferation of HUVEC, NIH3T3, HCT-116, and NIH3T3-Ki-Ras (Fig. 4B-E), with IC₅₀ values similar to XRP44X (Table III). These results show that XRP44X and CA4 have similar effects on cells and may act by similar mechanisms ; however the effect of XRP44X is superior to the effect of CA4

Table V. Tubulin polymerization and Colchicine competition

Tubulin polymerization:

Tubulin (10 μM) was polymerized in the presence relevant concentrations of the compounds. The drug was added to the tubulin solution in RB/2 30% glycerol buffer at 0⁰C just prior to assembly. The polymerization was induced at 37°C by addition of 6 niM MgC12 and 1 mM GTP. The final buffer composition was 0.05 M MES-NaOH pH 6.8, 6.25 mM MgC12, 0.5 mM EGTA, 3.4 M glycerol and 1.2 mM GTP. IC_5O is the concentration of drug for which the lag time was twice that of the control. This value was determined by visual inspection of the curves.

Colchicine competition:

Tubulin (lOμM) was incubated with 40 μM [3H]-colchicine and increasing concentrations of drug (from 2.5 to 100 μM) for 2 h at 28°C in a buffer consisting of 100 mM MES-NaOH pH6.8, 1 mM EGTA, 0.5 mM MgC12 and 0.5mM GTP (RB buffer). 90 μl aliquots were loaded on DEAE-cellulose discs (DE81, Whatman) which tightly binds tubulin. After a 10 min incubation at 0°C, the unbound radioactive colchicine was removed by five successive 5 min wash steps at 0°C with 30-40 ml phosphate buffer (10 mM, pH6.8). The filters were analyzed by liquid scintillation counting using Aquasol-2 (Dupont NEN). The non-specific binding of [3H]-co lchicine to the filters was negligible (less than 1%) and 30% of the tubulin- colchicine complexes remained bound after the 5 wash steps.

EXAMPLE 9: CA4 efficiently inhibits Net phosphorylation and activation of the Erk pathway by FGF-2 in contrast to docetaxel, vincristine, or nocodazole. Tubulin-interacting molecules bind to different sites and have different effects on microtubules (28). The Inventors compared the effects of XRP44X with CA4 that binds to the same site of tubulin, as well as with docetaxel that interacts with the taxane site and stabilizes microtubules and vincristine that interacts with the Vinca site and blocks tubulin assembly. HUVEC cells were treated for 90 min with increasing amounts of the compounds, and Net phosphorylation induced by FGF-2 was examined by Western blotting (Fig. 6A). CA4 inhibited Net phosphorylation at similar concentrations as XRP44X (IC₅₀, ~ 20 nmol/L; Fig. 6A, lanes 1-12). In contrast, docetaxel did not affect Net phosphorylation, even when the concentration was increased to much higher levels than XRP44X or CA4 (lanes 13-18). Vincristine also had little effect on Net phosphorylation (lanes 19-24; IC50, > 1 μmol/L). They tested nocodazole that also binds to the colchicine site. They found that nocodazole was significantly less efficient than XRP44X in inhibiting Net phosphorylation (lanes 25- 30). The compounds did not affect the amounts of the internal control (GAPDH; data not shown). Similar results were obtained in NIH3T3 cells (Table VI and Fig. 11).

Table VI. Inhibition of Net phosphorylation in HUVEC and NIH3T3 by tubulin interactin molecules

HUVEC and NIH3T3 cells were incubated for 4 h in 0.1% FCS, 90 min (HUVEC) or 3 h (NIH3T3) with the indicated compounds, 10 min with 20 ng/ml FGF-2 and analyzed by Western blotting with MAb2F3 to detect phospho-Net (P- Net). The IC50 were estimated from 3 or more independent titration experiments. Digital images were captured with Chemidoc (BioRad) and band intensity was quantified using Chemidoc software (BioRad Quantity One). The values given should be considered as being semi-quantitative; because of the Western blot methodology used in theses experiments. The chemical family, binding site and effect on microtubules of the compounds are shown (28). The Inventors also tested whether CA4 affects the Erk signalling cascade (Fig. 6B and C). CA4 inhibited FGF-2-induced expression of egr-1 and c-fos (Fig. 7A and B) to a similar extent as XRP44X and with a similar dose response (Fig. 7E and F). CA4 also inhibited phosphorylation of Rsk, Erk- 1/2, Mek-1, and Raf-1 (Fig. 6B, lanes 1-13; the inhibition of Raf-1 by XRP44X and CA4 was confirmed by quantification of scans and correction for the internal control GAPDH; data not shown). CA4 also inhibited activation of Ras (Fig. 6C). The inhibition of Ras activation using an ELISA assay (Fig. 10) was confirmed. In contrast, docetaxel did not inhibit, but rather had a small positive effect on Erk- 1/2 activation that was observed in this and some other experiments (Fig. 6B, lanes 14-20; data not shown). Similarly, nocodazole had no prominent effect on the Erk signalling cascade under these conditions (lanes 21-26; data not shown). In line with the positive effect of docetaxel on Erk- 1/2, it was found to increase FGF-2 induction of the endogenous c- fos and egr-1 genes (Table II). Docetaxel and U0126 (that inhibits Mek-1) did not affect Ras activation (Fig. 6C; data not shown). These results provide evidence that XRP44X and CA4 have similar mechanisms, which are not common to other classes of tubulin binders and even to nocodazole that belongs to colchicine site binder class. EXAMPLE 10: In vivo tests in nude mice with metastases from lung carcinoma, glioma and human prostate cancer Cell lines Three cell lines were used to follow tumour growth and metastasis in nude mice, LLCl (LL/2) Lewis Lung Carcinoma (ATCC CRL- 1642), C6 glioma cells (ATCC CCL-107) and PC3 cells. PC3 is a prostate cancer bone metastasis cell line (Kaighn ME, Shankar N, Ohnuki Y, Lechner F₃ Jones LW. Establishment and characterization of a human prostatic carcinoma cell line (PC.3). Invest Urol 1979 ; 17 : 16-23). The PC3-M-Pro4 subline was developed for its metastastatic capacity in mice. A derivative cell line constitutively expressing lucif erase was used in the experiments (Clin Exp Metastasis. 2007;24(8):699-705. Advances in optical imaging and novel model systems for cancer metastasis research. Henriquez NV, van Overveld PG, Que I₅ Buijs JT, Bachelier R, Kaijzel EL, Lδwik CW, Clezardin P, van der Pluijm G.).

Treatment with XRP44X Experiments were performed on animal models of cancer growth and metastasis, using highly metastatic cell lines in nude mice, derived from lung carcinoma, glioma and human prostate cancer (Fig. 12-20).

The Inventors first showed that XRP44X inhibited Net phosphorylation induced by FGF-2 in LLCl and C6 cells lines (figure 12). LLCl and C6 cells were then injected subcutaneously into nude mice, and after 6 days the mice were injected in the peritoneum with 1 mg/kg of XRP44X every day. The effects on tumour growth were measured with callipers for 18 (LLCl) or 26 (C6) days, after which the mice were sacrificed, the tumours were weighed, and the lungs were examined for the presence of metastases (figure 13). XRP44X inhibited the growth of primary tumours formed by both cell lines, as well as the final weight of the tumours at sacrifice. The lungs of the XRP44X treated mice had a statistically significant decrease in the number of metastases compared to the controls (figure 13). Similar results were obtained in three separate experiments, in which 5 mice were used for each condition and cell line. However the results are superiro for XRP44X than for CA4 (figure 15)

Prostate cancer metastases predominantly to the bone through a number of steps. Prostate cancer bone metastasis was followed by injection of .1O⁵ human prostate cancer metastasis cells (PC3), engineered to express luciferase (PC3- M-Pro4 luciferase), into the left ventricle of the heart, and metastases to the bone or the lung were followed (Figures 12-16). The mice were treated daily with 1 mg/kg of XRP44X, combretastatin A4 (CA4), or vehicle. Metastases were detected by bioluminescence (BLI) after 0, 7, 14, 21 and 24 days (Figures 16, 18-19). The body weight of the animals was similar after at the end of the experiment (Figure 17). The number of metastases were decreased by about 50% in XRP44X and CA4 treated cells at all time points with detectable metastases (7-21 days, Figures 18-19). The tumour burden was decreased by about 80% after 21 days (Figure 20). These results reveal that XRP44X decreases the growth of tumours and the formation of metastases in nude mice. XRP44X is more effective thant CA4 in inhibition of tumour metastasis.

Efficacy of XRP44X on established tumours

The Inventors have also shown that XRP44X is effective on established tumours (Figure 21).

LLCl and C6 tumours were inoculated sub-cutaneously into nude mice, and XRP44X treatment was started when the tumours became established. XRP44X inhibited tumour growth compared to control tumours when the mice were sacrificed. These results show that XRP44X is also active in a curative setting. Markers for evaluating the efficacy ofXRP44X

The Inventors have analysed RNA expression in tumours from animals that had been treated with XRP44X and were not treated. The C6 and LLCl tumours were analysed by Atlas Mouse Cancer 1.2 Array" and "Atlas Mouse cDNA Expression Array". The fold up-regulation of some of the genes were: 3.95 ephrin Bl, 3.33 tolloid-like, 3.2 cyclin E2, 2.5 oncostatin M, 2.5 follistatin, 1.7 interferon gamma receptor 2, Fold changes in down-regulated genes included : 0.4 cysteine proteinase inhibitor, 0.48 MAPK 13, 0.51 MMP 3, 0.52 serine/threonine kinase 25, 0.54 MAPKAPK 2, 0.54 protein tyrosine phosphatase, 0.56 macrophage stimulating 1 receptor, 0.6 colony stimulating factor 1 receptor, 0.6 tyrosine kinase receptor 1, 0.63 PI 3 kinase, 0.65 FGFRl, 0.65 IGFBPl. In cell culture, similar analyses identified many interesting changes, including inhibition of Net (0.5 fold) and upregulation of tubulin cofactor A (3.4). Interestingly, tubulin cofactor A is linked to tubulin de- polymerisation, indicating a pathway by which XRP44X may trigger signalling. Additional interesting changes were modulation of expression of genes involved in apoptosis (BAD 2.0, p53 1.7 etc.), integrins (betal 0.5, alpha3 0.5, etc.), oncoproteins (c-myc 0.4, SRC 0.5, AbI 0.3, etc.), kinases (ERKl 0.3, PKB 0.4, etc.) and angiogenesis (VEGF 0.5). These results indicate important pathways that contribute to the tumour inhibitory properties of XRP44X that could be exploited to study the mechanisms of XRP44X functions and be used as markers to follow treatment efficacy in the clinic (Figures 22-23). EXAMPLE 11: Discussion and conclusions The Inventors have identified an inhibitor of Ras-induced transcription activation through the MAPK pathway. It inhibits growth factor-induced gene expression through the Erk signalling pathway, alters the morphology of microtubules and the actin cytoskeleton, affects transcription regulation, and blocks cell cycle progression and microvessel sprouting. Different mechanisms may contribute to the effects observed in these short, medium, and long-term assays. One of the interesting properties is that it is a microtubule poison, a class of molecules already successfully used in cancer treatment. Microtubule poisons have different effects and fall into distinct classes based on their effects on tubulin and microtubule dynamics and also on "additional" effects that are increasingly being investigated. Understanding these, "secondary" pathways are important for the design and optimum use of cancer therapeutics. The inhibitor XRP44X was identified in a cell-based screen for decreased luciferase activity driven by Ras-induced activation of Net. XRP44X is an efficient inhibitor of Ras-Erk-mediated phosphorylation of Net (IC_5O, 10—20 nmol/L). Compound inhibitory activity is structurally specific because the regioisomer XRP45X and close analogues (XRP57X and XRP58X) are much less efficient. The screen was focused on the Ras-Net pathway, with a counter selection for compounds that affected the β-catenin/T-cell factor pathway. In short-term transfections, XRP44X inhibited Ras induced activation of both the fusion proteins used in the original screen (Gal4-N5; data not shown), as well as full-length Net with a different reporter, without having an effect on the internal control. XRP44X also inhibited the expression of several endogenous genes that are induced by the Ras-Erk pathway, c-fos and egr-J. These results indicate that XRP44X is relatively selective and specific in its effects.

The Inventors investigated the mechanisms by which XRP44X affects the Ras-Net pathway. The COOH terminal domain of Net used in the screen is activated by Erk phosphorylation on Ser³⁶³, which can be followed with a phosphorylated-specific antibody (21). Treatment of different cell types with XRP44X inhibited phosphorylation of endogenous Net on Ser³⁶³. We traced the origins of the inhibition by working backwards along the pathway. Net is regulated by nuclear export in response to several stress-induced pathways (29). Net remained in the nucleus under the conditions used (see Fig. 2; Fig. 9 and data not shown), indicating that XRP44X did not significantly induce export of Net but rather suggesting that it inhibited Erk-1/2 activity. Erks are activated by phosphorylation in the cytoplasm, and they, in turn, phosphorylate cytoplasmic proteins and nuclear proteins after migration into the nucleus (30).

Inhibition of nuclear import of Erk-1/2 could have led to decreased phosphorylation of Net, which is found in the nucleus. However, the Inventors did not observe effects on nuclear import (data not shown) in agreement with other studies (review ref. 31). They showed that phosphorylation of Erk was inhibited and that the remaining detectable activated Erk-1/2 was found in both the cytoplasm and nucleus, using immunocytochemistry and subcellular fractionation (see above and data not shown). These results indicated that the major effect of XRP44X was upstream from Erk-1/2. They traced the inhibition upstream through Mekl/2, Raf-1, and Ras-GTP, showing that XRP44X inhibits Ras activation. This inhibition could come from effects of XRP44X on the cytoskeleton. Cell staining for actin and tubulin showed alterations in cytoskeletal architecture. XRP44X stimulates microtubule depolymerization in vitro and competes with colchicine for binding to tubulin. CA4 has similar effects on the cytoskeleton and microtubules (27, 32, 33), inhibits the Ras-Net signalling pathway (this study), and induces early membrane blebbing through a mechanism that involves activated Erks (25), suggesting that they act by similar mechanisms. Interestingly, nocodazole, which also belongs to colchicine "binder" class of compounds, does not inhibit the Ras-Net signalling pathway, demonstrating that microtubule depolymerization can be uncoupled from inhibition of this pathway. Despite ~ 20 years of research since the original isolation and synthesis of CA4 (34), the precise mechanisms by which it operates are incompletely understood. Importantly, CA4 has been shown to rapidly activate the small GTPase Rho and Rho- kinase (25). In line with this, the Inventors have found that XRP44X affects ezrin expression and phosphorylation, using macroarrays and phosphorylated-specific antibodies (data not shown). Ezrin belongs to the ezrin/radixin/moesin (ERM) family of actin binding proteins that act as signal transducers in response to cytoskeleton remodeling. ERM proteins are linked to Rho signalling through several pathways (35). Further studies focused on already described endogenous inhibitors of the Ras-Erk pathway (review ref. 36) may help to unravel the molecular mechanism by which CA4 and XRP44X selectively affect cellular signalling. As expected for a microtubule poison, XRP44X in cell culture inhibits cell proliferation and leads to the accumulation of cells in the G₂-M phase without obvious cell type specificity. XRP44X inhibits sprouting from aorta in ex vivo experiments (see above). XRP44X behaves as a typical tubulin poison that binds to the colchicine-binding site. The effects of XRP44X are very similar to those described for combretastatins (review ref. 27), suggesting by analogy that XRP44X is potentially a vascular-disrupting agent.

Interestingly, the Inventors have shown that Net is expressed at sites of angiogenesis and tumorigenesis during development and has a role in angiogenesis in in vitro, ex vivo, and in vivo assays (8—10), suggesting that targeting Net in the screen for XRP44X favored selection of a vascular-disrupting agent. However, XRP44X, like combretastatins, is not specific for endothelial cells, and the relative importance of its effects on different cell types (endothelial cells, tumor cells) in inhibition of tumor growth and metastasis has now been established, as it emerges from example 10 above. Indeed, there was non reason, in view of the in vitro data, that XRP44X would effectively work in vivo.

Many microtubule-targeted drugs have been described, and microtubules are good targets for anticancer therapy (review refs. 13, 14). The drugs bind to different sites on tubulin, in particular the taxane, Vinca, and colchicine domains. Taxanes stabilize microtubules, whereas Vinca alkaloids, nocodazole, combretastatins, and XRP44X destabilize microtubules (Table VI). Differences in their effects on microtubules are probably reflected in the biological properties of the drugs. The Inventors found that docetaxel did not inhibit Ras-Net signalling, and vincristine was much less efficient (IC₅₀, ~ 1 μmol/L). These results agree with other studies that show that paclitaxel does not inhibit MAPK activation (37, 38). Furthermore, the Inventors found that docetaxel has a slight positive effect on c-fos expression in contrast to XRP44X. Similar effects on c-fos expression and associated activation of Erk-1/2 have been described recently (39, 40). Taxoids and microtubule- destabilizing agents have opposite effects on c-myc oncogene expression in some cell types (41) through mechanisms involving nuclear factor-κB (NF-κB; ref. 42). They have been reported to use the NF-κB pathway to stabilize HIF- lα, a factor that is important for wound healing and angiogenesis by regulation of cell response to hypoxia (43). Interestingly, Net is also implicated in wound healing, angiogenesis, and the response to hypoxia (refs. 8-10; data not shown), indicating that MDAs may regulate several different pathways that are important in common physiologic processes. Knowledge of the differences in transcription factor control by microtubule-targeted drugs may be used to increase their therapeutic potential. Fascinatingly, the therapeutic efficacy of paclitaxel can be enhanced by inhibition of the Erk activator Mek in nude mice bearing human heterotransplants (44), and its ability to induce apoptosis can be enhanced by inhibition of NF-κB (45). The differences in the efficiencies of inhibition of the Ras-Net pathway by docetaxel, vincristine, and CA4/XRP44X could be a consequence of them binding to different sites on tubulin. However, another colchicines-binding compound, nocodazole, did not inhibit the pathway efficiently.

In conclusion, the Inventors have shown that, among microtubule poisons, XRP44X and CA4 constitute an original class of drugs, which combine two anticancer clinically validated mechanisms: antimitotic and signalling pathway inhibitory activities (46).

Furthermore, they have proved the in vivo value and efficiency of XRP44X; which is more effective that CA4. Thus, XRP44X is a powerful drug, especially for inhibiting metastasis, with the following properties:

It inhibits growth factor induced Ras-MAPK signalling It affects gene expression

It alters microtubules and the actin cytoskeleton

It blocks cell cycle progression

It blocks microvessel sprouting and

It inhibits tumour growth and metastasis in animals. References

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Claims

CLAIMS 1°) Compound of formula 1

wherein

R₁ is a C₁-C₆ alkyl group, substituted or not, linear or branched and R₂ represents a halogen atom, as a drug for treating solid cancers or preventing metastases of solid cancers, said solid cancers being selected in the group consisting of lung cancer, glioma and prostate cancer. 2°) Compound of claim 1 characterized in that said halogen atom is selected in the group consisting of chlorine, fluorine, bromine and iodine.

3°) Compound of claim 1 or of claim 2, characterized in that it corresponds to 3-piperazinylcarbonyl-pyrazole, wherein R₁ represents a methyl and R₂ represents a chlorine atom, named XRP44X, as a drug for treating solid cancers or preventing metastases of solid cancers, said solid cancers being selected in the group consisting of lung cancer, glioma and prostate cancer.

4°) Pharmaceutical composition characterized in that it comprises a compound of claims 1 to 3 and at least a pharmaceutically acceptable vehicle.

5°) Compound of claims 1 to 3 as a drug for treating pathologies where angiogenesis is to be inhibited.

6°) Compound of claim 5, characterized in that said pathologies are selected among dermatology, ophthalmology, rheumatology, endometriosis and inflammatory diseases.