TRPC6 channel inhibition disturbs store-operated Ca2+ entry to delay proliferation in bladder cancer

Abstract

Background and ObjectiveDespite its prevalence, bladder cancer (BC) remains an unsolved pathogenesis. It is believed that TRPC6 channels have unique electrophysiological properties that contribute to intracellular Ca2+ signalling and tumorigenesis in cells. However, the mechanism by which TRPC6 contributes to BC progression and intracellular Ca2+ homeostasis remains unclear. MethodIn this study, TRPC6 expressions in paired BC and adjacent normal tissues were measured by immunohistochemistry. A KEGG pathway enrichment analysis was conducted to determine TRPC6s potential contribution to BC. Ca2+ imaging analysis was performed to explore the contribution of TRPC6 in the BC cell. Flow cytometry and Cell Counting Kit-8 assay were performed to explore the effects of TRPC6 on the proliferation of BC. The impacts of TRPC6 SOCE on PI3K/Akt/mTOR pathway were measured by western blot. Based on the above bunch of studies, TRPC6 was found to be overexpressed in human BC tissue, which correlated with poor survival rates for patient overall survival (OS). We used the TRPC6-specific antagonist SAR7334 to explore and reveal significant inhibition of BC cell proliferation. Mechanistically, TRPC6 mediated cytosolic Ca2+ and regulation of SOCE, leading to the activation of the IP3K/AKT/mTOR pathway. ResultsWe found that SAR7334 arrested the phosphorylation of PI3K and Akt, thus causing a significant decrease in phosphorylated mTOR. Similar effects were observed for the SOCE-specific antagonist MRS1845. In contrast, the Akt inhibitor MK2206 did not alter the SOCE in BC cells. Conclusionsour results indicate that the pharmacological inhibition of TRPC6 arrests tumour cell proliferation through SOCE targeting the PI3K/Akt/mTOR pathway. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=101 SRC="FIGDIR/small/702689v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@bf783aorg.highwire.dtl.DTLVardef@6e3487org.highwire.dtl.DTLVardef@13aad23org.highwire.dtl.DTLVardef@13cfe7e_HPS_FORMAT_FIGEXP M_FIG C_FIG Schematic of proposed pathway. A model for summarizing TRPC6 contributes to cell proliferation in bladder cancer. TRPC6 specific inhibitor SAR7334 alter cellular cytosolic Ca2+ and SOCE, thus arrested phosphorylation of the PI3K/Akt pathway and the proliferation of bladder cancer cells.