Int J Med Sci 2012; 9(3):216-224. doi:10.7150/ijms.4004
Effects of STAT3 Gene Silencing and Rapamycin on Apoptosis in Hepatocarcinoma Cells
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.
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
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.