The effect of hyperforin which is the specific activator of the TRPC6 on proliferation rate and SOCE in Huh-7 human hepatocellular carcinoma cells

Objectives: The purpose of our study was to investigate the potential effects of hyperforin which is the specific activator of the transient receptor potential canonical 6 (TRPC6) channel on proliferation rate, store-operated calcium entry (SOCE) and expression of SOCE-related proteins (TRPC1, TRPC6, STIM1 and Orai1) in Huh-7 human hepatocellular carcinoma cell line. Methods: In this study, real-time quantitative PCR (qRT-PCR, Light Cycler 480, Roche) analysis was performed to investigate the effects of hyperforin incubation (24 h) on mRNA expression levels of TRPC1, TRPC6, STIM1 and Orai1. In order to investigate the effects of hyperforin on SOCE, changes in intracellular calcium concentrations in Fura-2-loaded Huh-7 cells were monitored on a spectroflurometer in real time. In addition, the effects of hyperforin on the proliferation of Huh-7 cells were examined using the real-time cell analysis system (xCELLigence). Results: According to qRT-PCR results, hyperforin induced statistically significant increase in TRPC1 mRNA expression levels while STIM1 and Orai1 levels were decreased. On the other hand, although not statistically significant there was a significant increase in TRPC6 mRNA expression levels. CPA-induced SOCE was significantly increased in Huh-7 cells incubated with hyperforin (2 h) compared to control cells. At the same time, hyperforin application as alone or after CPA-mediated SOCE caused an increase in intracellular calcium levels. In order to investigate the role of protein kinase C in calcium concentration increases caused by hyperforin, in the presence of the PKC inhibitor Chelerythrine, hyperforin-induced [Ca+2]i increasing was significantly reduced. Hyperforin caused a significant concentration dependent inhibition in the rate of proliferation of Huh-7 cells. Conclusions: Hyperforin-induced potentiating of SOCE may be result of increases in mRNA expression levels of TRPC1 and TRPC6. Inhibitor effects of hyperforin on Huh-7 cells suggest us that hyperforin may be a potential drug for cancer treatment. Furthermore, hyperforin may play an important role in activation and regulation of SOCE in hepatocellular carcinoma cells. Keywords; Hepatocellular carcinoma; Huh-7; Calcium; TRPC1; TRPC6