Anti-tumor activity of the TRPM8 inhibitor BCTC in prostate cancer DU145 cells

The present study investigated the anti-tumor activity of N-(4-tertiarybutylphenyl)-4-(3-chloropyridin-2-yl)tetra0hydropyrazine-1(2H)-carbox-amide (BCTC), a potent and specific inhibitor of transient receptor potential cation channel subfamily M member 8 (TRPM8) in prostate cancer (PCa) DU145 cells. TRPM8 expression in DU145 and normal prostate PNT1A cells was detected by reverse transcription polymerase chain reaction and western blot analysis. The effect of BCTC on DU145 cells was analyzed by flow cytometry analysis, and MTT, scratch motility and Transwell invasion assays. The molecular mechanism through which BCTC acts was investigated by western blot analysis. TRPM8 expression was increased in DU145 cells compared with PNT1A cells at the mRNA and protein levels. The present study provided evidence that inhibition of TRPM8 by BCTC reduced the viability of DU145 cells, but not PNT1A cells. In addition, BCTC inhibited cell cycle progression, migration and invasion in DU145 cells. Cell cycle-associated proteins, including phosphorylated protein kinase B, cyclin D1, cyclin dependent kinase (CDK) 2 and CDK6 were downregulated by BCTC, while phosphorylated glycogen synthase kinase 3 beta was upregulated. However, investigations in the present study revealed that BCTC failed to trigger apoptosis in DU145 cells. In addition, in BCTC-treated DU145 cells, phosphorylated extracellular signal-regulated kinase 1/2 was downregulated substantially while phosphorylated p38 (p-p38) and phosphorylated c-Jun N-terminal kinases (p-JNK) were upregulated. The anti-proliferative activity of BCTC on DU145 cells was attenuated by p38 and JNK-specific inhibitors, suggesting that MAPK pathways are involved. Overall, the TRPM8 specific antagonist BCTC demonstrated excellent anti-tumor activity in PCa DU145 cells, and therefore has the potential to become a targeted therapeutic strategy against PCa.