Sestrin 2(SESN2) promotes primary resistance to sorafenib by activating AKT in hepatocellular carcinoma cells

: Objective To explore the role of sestrin2 (SESN2) in sorafenib primary resistance and the underlying mechanism in hepatocellular carcinoma (HCC) cells. Methods Real-time quantitative PCR (qRT-PCR) and Western blot analysis were performed to examine SESN2 mRNA and protein levels in Bel-7404, SNU-398, HLE, HLF and Hep3B cell lines. Immunohistochemical staining was used to detect SESN2 expression in HCC tissues. After the treatment of 0, 2, 5, 10, 15, 20, 25 μmol/L sorafenib for 24 hours, CCK-8 assay was performed to detect the cell viability and subsequent IC50 of sorafenib in the above HCC cell lines. After the treatment of 0, 2, 4, 6, 8 μmol/L sorafenib for 24 hours, qRT-PCR and Western blot analysis were conducted to measure the alterations of SESN2 mRNA and protein expressions in Bel-7404 and SNU-398 cells. CCK-8 assay and flow cytometry were performed to examine the viability and apoptosis of Bel-7404 and SNU-398 cells after sorafenib treatment with or without SESN2 knockdown by siRNA transfection. Western blot analysis was used to test the expressions of AKT and phosphorylated-AKT. Results Compared with the control, SESN2 expression markedly increased in both HCC cell lines and tissues and there was a positive correlation between SESN2 expression and IC50 of sorafenib in different HCC cell lines. Subsequently, the mRNA and protein levels of SESN2 were significantly elevated after sorafenib treatment in Bel-7404 and SNU-398 cells, and SESN2 knockdown led to decreased cell viability and increased cell apoptosis after sorafenib treatment. More importantly, SESN2 knockdown impaired sorafenib-induced AKT activation in HCC cells. Conclusion SESN2 up-regulation conferred primary resistance to sorafenib by activating AKT in HCC cells.