Functions of endothelin-1 in apoptosis and migration in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of cancer mortality in China and the third leading cause of cancer mortality worldwide. The mechanisms involved in the development and progression of HCC are not well understood. In the present study, the functions of endothelin-1 (ET-1) in HCC were studied and its underlying mechanisms were investigated. ET-1, B-cell lymphoma 2 (Bcl-2), Bcl-2 related protein 4 (Bax), matrix metalloproteinase (MMP)-2 and MMP-9 expression was measured by reverse transcription-quantitative polymerase chain reaction and western blotting. Cell proliferation was measured via Cell Counting kit-8 assay. Flow cytometry was performed for cell cycle and apoptosis analysis. Migration was measured via Transwell assay. The results demonstrated that ET-1 expression significantly increased in HCC tissues compared with the normal tissues of patients in The Cancer Genome Atlas dataset (P<0.01). Furthermore, downregulation of ET-1 was able to significantly inhibit cell proliferation and growth in vitro (P<0.01) and in vivo (P<0.01), and induce cell cycle arrest (P<0.05) and apoptosis (P<0.01) in the HCC SMMC-7721 cell line. Bioinformatics analysis demonstrated that the cell apoptosis signaling pathway was activated by ET-1. The ratio of B-cell lymphoma (Bcl-2) -related protein 4 (Bax)/Bcl-2 was significantly increased by downregulation of ET-1 (P<0.01). ET-1 downregulation also inhibited migration of SMMC-7721 cells (P<0.05) via decreasing levels of matrix metalloproteinase (MMP) -2 (P<0.05) and MMP-9 (P>0.05). These results suggest that ET-1 may be able to affect the apoptosis and migration of HCC cells via modulation of the Bax/Bcl-2 ratio and expression levels of MMP-2 and MMP-9, which indicates that ET-1 maybe a potential novel target for HCC treatment.