MiR-21 mediates sorafenib resistance of hepatocellular carcinoma cells by inhibiting autophagy via the PTEN/Akt pathway
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Changjun He1,2,3, Xuesong Dong3, Bo Zhai3, Xian Jiang3, Deli Dong2, Baoxin Li2, Hongchi Jiang3, Shidong Xu1, Xueying Sun3
1Department of Surgery, the Affiliated Cancer Hospital of Harbin Medical University, Harbin, China
2Department of Pharmacology, the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Harbin Medical University, Harbin, China
3The Hepatosplenic Surgery Center, Department of General Surgery, the First Affiliated Hospital of Harbin Medical University, Harbin, China
Shidong Xu, e-mail: firstname.lastname@example.org
Keywords: sorafenib, hepatocellular carcinoma, miR-21, phosphatase and tensin homolog, Akt, autophagy
Received: March 23, 2015 Accepted: July 17, 2015 Published: July 30, 2015
Sorafenib resistance remains a major obstacle for the effective treatments of hepatocellular carcinoma (HCC). Recent studies indicate that activated Akt contributes to the acquired resistance to sorafenib, and miR-21 dysregulates phosphatase and tensin homolog (PTEN), which inhibits Akt activation. Sorafenib-resistant HCC cells were shown to be refractory to sorafenib-induced growth inhibition and apoptosis. Akt and its downstream factors were highly activated and/or upregulated in sorafenib-resistant cells. Inhibition of autophagy decreased the sensitivity of sorafenib-resistant cells to sorafenib, while its induction had the opposite effect. Differential screening of miRNAs showed higher levels of miR-21 in sorafenib-resistant HCC cells. Exposure of HCC cells to sorafenib led to an increase in miR-21 expression, a decrease in PTEN expression and sequential Akt activation. Transfection of miR-21 mimics in HCC cells restored sorafenib resistance by inhibiting autophagy. Anti-miR-21 oligonucleotides re-sensitized sorafenib-resistant cells by promoting autophagy. Inhibition of miR-21 enhances the efficacy of sorafenib in treating sorafenib-resistant HCC tumors in vivo. We conclude that miR-21 participates in the acquired resistance of sorafenib by suppresing autophagy through the Akt/PTEN pathway. MiR-21 could serve as a therapeutic target for overcoming sorafenib resistance in the treatment of HCC.
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