Effects of chemokine receptor 5 (CCR5) blockage on cell survival and expression levels of apoptosis related genes (FAS, FASL) in hepatocellular carcinoma cells

Abstract

Background: Hepatocellular carcinoma (HCC) is a malignant tumor which arises from the liver cells (hepatocytes). HCC is 3^rd leading cause of cancer related mortalities worldwide. Various treatment strategies for HCC include surgery, radiotherapy, targeted agents and chemotherapy. Despite the availability of diverse therapeutic options, 5-year survival rates are low (10-30%) especially in advanced stages of HCC. This, in turn, highlights the need to identify new therapeutic targets/compounds for HCC treatment. Purpose of this study was to evaluate effects of blocking a chemokine receptor (CCR5) on cell proliferation and apoptosis related genes (FAS/FASL) in HCC cells (HepG2).

Materials & Methods: CCR5 receptor was blocked by using an FDA approved antagonist (Maraviroc) in HepG2 cells and effects on proliferation were identified. For this purpose, the cells were exposed to various concentrations (7.5-500µM) of the test compound and cell viability was monitored by MTT dye reduction assay for 24, 48 and 72 hours. Afterwards, HepG2 cells were exposed to three distinct concentrations of maraviroc (IC₂₅, IC₅₀, IC₇₅) in a separate experiment and expressional modulations in two apoptosis related genes (FAS and FASL) were identified by qRT-PCR methodology.

Results: The results indicated that blocking CCR5 via maraviroc induced substantial anti-proliferative effects in HepG2 cells. The effects were time and concentration dependent and were especially clearer following exposure with 100µM of maraviroc. Blockage of CCR5 induced marginal up-regulation of FAS gene in the cells. In contrast, blocking of CCR5 inhibited the expression of FASL gene in HepG2 cells in a concentration dependent format with a maximum inhibition of 5fold.  

Conclusion: CCR5 blockage by maraviroc induces prominent cytotoxic effects in HCC cancer cells. Expressional modulations in apoptosis related genes are imposed in response to blockage of the chemokine receptor in the cells. Further studies are needed to understand the precise nature of growth inhibitory effects observed in response to blockage of CCR5 in HepG2 cells.