bms-777607 and Prostatic-Neoplasms

The c-Met receptor tyrosine kinase is aberrantly activated in many solid tumors. In a prior study we showed that prostate cancer PC-3 cells exhibit constitutively activated c-Met without exogenous hepatocyte growth factor (HGF); however whether this characteristic is due to an endogenous HGF/c-Met autocrine loop remains controversial. In the current study we examined the response of PC-3 cells to an anti-HGF neutralizing antibody or a small molecule Met kinase inhibitor (BMS-777607).. Cell scattering was tested by monitoring cell morphology after HGF stimulation. Cell migration was examined by both "wound-healing" and transwell assasy and invasion was detected by Matrigel-coated transwell assay. Proliferation, survival and anoikis were determined by MTT, colony formation and trypan blue exclusion assay, respectively. Gene and protein expression were assessed by real-time PCR and Western blot, respectively.. Although HGF mRNA could be detected in PC-3 cells, the molecular weight of secreted "HGF" protein was inconsistent with the functional recombinant HGF. Furthermore, conditioned medium from PC-3 cell cultures was ineffective at triggering either motogenic behavior or c-Met signaling in DU145, another prostate cancer cell line expressing c-Met but lacking basal c-Met activation. PC-3 cells also were not responsive to the anti-HGF neutralizing antibody in experiments assessing proliferation, migration, or c-Met signaling. BMS-777607 treatment with micromolar doses nonetheless led to significant inhibition of multiple PC-3 cell functions including proliferation, clonogenicity, migration and invasion. At the molecular level, BMS-777607 suppressed autophosphorylated c-Met and downstream c-Src and Akt pathways.. These results suggest that the constitutive c-Met activation in PC-3 is independent of autocrine stimulation. Because PC-3 cells were responsive to BMS-777607 but not the anti-HGF antibody, the findings also indicate that under circumstances where c-Met is constitutively hyperactive in the absence of functional HGF, targeting the c-Met receptor remains a viable therapeutic option to impede cancer progression.

Topics: Aminopyridines; Antibodies, Neutralizing; Autocrine Communication; Cell Line, Tumor; Gene Expression Regulation, Neoplastic; Hepatocyte Growth Factor; Humans; Male; Prostatic Neoplasms; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-met; Pyridones; RNA, Messenger; Signal Transduction

Most prostate cancer-related deaths are due to advanced disease with patients with metastatic prostate cancer having a 5-year survival rate of only 34%. Overexpression of c-Met receptor tyrosine kinase has been highly associated with prostate cancer progression and metastasis. In the present studies, the effect of BMS-777607, a selective and potent small-molecule Met kinase inhibitor that has been advanced to clinical evaluation, on hepatocyte growth factor (HGF)-mediated cell functions and signaling pathways was evaluated in c-Met-expressing PC-3 and DU145 prostate cancer cells. BMS-777607 treatment had little effect on tumor cell growth but inhibited cell scattering activated by exogenous HGF, with almost complete inhibition at 0.5 micromol/L in PC-3 and DU145 cells. This agent also suppressed HGF-stimulated cell migration and invasion in a dose-dependent fashion (IC(50) < 0.1 micromol/L) in both cell lines. Mechanistically, nanomolar doses of BMS-777607 potently blocked HGF-stimulated c-Met autophosphorylation and downstream activation of Akt and extracellular signal-regulated kinase. In addition, both wortmannin and U0126, but not dasatinib, attenuated cell scattering and migration induced by HGF, suggesting the involvement of the phosphoinositide 3-kinase and mitogen-activated protein kinase pathways, but not of Src or focal adhesion kinase, in HGF-mediated motogenic effects. Taken together, these data indicate that the downregulation of c-Met signaling by BMS-777607 treatment can significantly disrupt key steps in the metastatic cascade, suggesting that such a targeting strategy may hold promise for the treatment of advanced prostate cancer.

Topics: Aminopyridines; Cell Line, Tumor; Cell Movement; Cell Proliferation; Drug Screening Assays, Antitumor; Extracellular Signal-Regulated MAP Kinases; Hepatocyte Growth Factor; Humans; Male; Neoplasm Invasiveness; Neoplasm Metastasis; Phenotype; Phosphatidylinositol 3-Kinases; Prostatic Neoplasms; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-met; Pyridones; Signal Transduction; Small Molecule Libraries