Sorafenib-induced Aquaporin-3 Downregulation is Coupled With Proliferation Inhibition and Increased Apoptosis in Hepatocellular Carcinoma Cells

Abstract

Background Sorafenib is the only targeted therapy promising to improve the prognosis of patients with advanced hepatocellular carcinoma (HCC), but its long-term clinical efficacy is limited due to chemotherapy resistance. The lack of a full understanding of the anti-tumor mechanism of sorafenib in HCC is attributed to the difficulties in understanding the mechanism of drug resistance. In recent years, a large number of preclinical and clinical data have confirmed the catalytic role of aquaporin-3 (AQP3) in a variety of tumors including HCC, but none of the studies reported the regulatory mechanism of AQP3 during sorafenib treatment. This study examined the effect of sorafenib on the expression of AQP3 in HCC cells and determined whether the effect is associated with cell proliferation inhibition, cell cycle arrest, and increased apoptotic. Methods mRNA and protein levels of AQP3 in hepatoma cell lines exposed to sorafenib or UO126 were detected via real-time quantitative polymerase chain reaction (qPCR) and western blotting, respectively. The effect of AQP3 expression changes on cell proliferation, cell cycle and apoptosis were determined by cell counting kit-8 (CCK-8) and flow cytometry. In addition, western blotting detected proteins involved in the regulation of proliferation and cell cycle progression. Results The results showed that AQP3 was down-regulated in all cell lines exposed to sorafenib or UO126 in a concentration dependent manner. The downregulation of AQP3 successfully inhibited cell proliferation, induced cell cycle arrest and increased cell apoptosis, while the reverse was true when AQP3 was overexpressed. Western blotting results showed that in AQP3 knockdown cells, the amounts of Erk, Akt, p53, p-Erk, p-Akt and cyclin-dependent kinase 2 (CDK2) decreased, while the amounts of cyclin-dependent kinase 4 (CDK4), p21 and p-p53 increased. Conclusion This study found that sorafenib may inhibit proliferation, induce cell cycle arrest, and increase apoptosis of HCC cells by regulating the expression of AQP3.