Int J Med Sci 2012; 9(3):216-224. doi:10.7150/ijms.4004

Research Paper

Effects of STAT3 Gene Silencing and Rapamycin on Apoptosis in Hepatocarcinoma Cells

Yi Zhang1*, Jun-Wei Zhang2*, Guo-Yue Lv 1, Shu-Li Xie3, Guang-Yi Wang1✉

1. Department of Hepatobiliary and Pancreatic Surgery, the First Hospital of Jilin University, Changchun ,130021, P. R. China;
2. Department of Oncology, the Third Hospital of Liaoning Medical University, Jinzhou,121000, P. R. China;
3. Research Laboratory, Department of General Surgery, the First Hospital of Jilin University, Changchun 130021, P. R. China.
* Yi Zhang and Jun-Wei Zhang contributed equally to the work.

Abstract

The PI3K/Akt/mTOR and JAK/STAT3 signaling pathways are important for regulating apoptosis, and are frequently activated in cancers. In this study, we targeted STAT3 and mTOR in human hepatocellular carcinoma Bel-7402 cells and examined the subsequent alterations in cellular apoptosis. The expression of STAT3 was silenced with small interfering RNA (siRNA)-expressing plasmid. The activity of mTOR was inhibited using rapamycin. Following treatment, Annexin V/propidium iodide staining followed by flow cytometry and Hoechst33258 immunofluorescence staining was used to examine cellular apoptosis. JC-1 staining was used to monitor depolarization of mitochondrial membrane (ΔΨm). Furthermore, the expression of activated caspase 3 protein was analyzed by Western blotting. Compared to non-treated or control siRNA-transfected cells, significantly higher levels of apoptosis were detected in siSTAT3-transfected or rapamycin-treated cells (P < 0.05), which was further enhanced in cells targeted for both molecules (P < 0.05). The pro-apoptotic effects were accompanied with concomitant depolarization of mitochondrial membrane and up-regulation of activated caspase 3. Combined treatments using rapamycin and STAT3 gene silencing significantly increases apoptosis in Bel-7402 cells, displaying more dramatic effect than any single treatment. This study provides evidence for targeting multiple molecules in cancer therapy.

Keywords: mTOR, STAT3, RNAi, rapamycin, apoptosis, hepatocelluar carcinoma.

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How to cite this article:
Zhang Y, Zhang JW, Lv GY, Xie SL, Wang GY. Effects of STAT3 Gene Silencing and Rapamycin on Apoptosis in Hepatocarcinoma Cells. Int J Med Sci 2012; 9(3):216-224. doi:10.7150/ijms.4004. Available from http://www.medsci.org/v09p0216.htm