Capsaicin promotes a more aggressive gene expression phenotype and invasiveness in null-TRPV1 urothelial cancer cells

Capsaicin (CPS) has been found to exhibit either tumor promoting or suppressing effects, many of which are mediated by the specific transient receptor potential vanilloid type-1 (TRPV1). Herein, we provide evidence that CPS treatment induced a more aggressive gene phenotype and invasiveness in 5637 cells-lacking TRPV1 receptor. CPS treatment of 5637 cells induced upregulation of pro-angiogenetic (angiopoietin 1, angiopoietin 2 and vascular endothelial growth factor), pro-invasive and pro-metastatic genes (MMP1, MMP9, TIMP1, TIMP3, granzyme A (GZMA), NM23A and S100A) with a downregulation of apoptotic genes (Fas/CD95 and tumor necrosis factor receptor superfamily member 1A). CPS increased the invasiveness of 5637 cells by triggering IGF (insulin-like growth factor)-1 release, GZMA and MMP9 activation, alpha-tubulin disassembly and cytoskeleton degradation. Finally, in order to evaluate the relationship between the lack of TRPV1 expression and increased CPS-induced invasiveness, we transfected 5637 cells with the TRPV1 complementary DNA (cDNA) sequence. We found that TRPV1-expressing cells show CPS-mediated calcium level increase, growth inhibition and apoptosis. Moreover, CPS-induced migration and MMP9 activation were reverted, suggesting an inhibitory role played by TRPV1 in urothelial cancer cell invasion and metastasis.