6-gingerol promotes G2/M phase cell cycle arrest and apoptosis in hepatocellular carcinoma

Abstract

6-Gingerol (6-G), an active biological natural polyphenolic compound extracted from ginger (Zingiber officinale) has been reported to exhibit promising anticancer activity over a panel of cell lines. Here, we evaluated 6-G significantly reduces the cell viability and clonogenic property, induces apoptosis characterized by activation of procaspase-3 and PARP1, and arrests cell cycle at the G2/M phase in hepatocellular carcinoma (HCC) cells. Cell viability and colony formation assays showed that 6-G inhibits cell proliferation and clonogenic property of HCC cells significantly in comparison to untreated control cells. Higher doses of 6-G activate apoptosis proteins caspase-3 and PARP1 as revealed by immunoblotting analysis. Annexin V FITC staining followed by flow cytometry demonstrates the induction of apoptosis in HCC cells, in a dose-dependent manner. Moreover, phase-contrast microscopy analysis revealed that the higher doses of 6-G display morphological changes in Huh7 cells. Further, the flow cytometry analysis showed that 6-G promotes significant arrest of the cell cycle at the G2/M phase when compared with untreated control cells. Additionally, immunoblotting results revealed that 6-G treatment abrogates Akt and Erk1/2 signaling in Huh7 cells. Further 6-G upregulates the cell cycle checkpoint proteins p27/ Kip1 and p21/Cip1 and concomitantly downregulates the expression of cyclin D1, c-Myc, and CDK4 in Huh7 cells. In conclusion, the present study provides evidence that 6-G exhibits significant antiproliferative effect by induces apoptosis and attenuates Akt/Erk1/2 signaling mediated G2/M phase arrest of the cell cycle in Huh7 cells.