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

• Main Author: Yi Zhang, Jun-Wei Zhang, Guo-Yue Lv, Shu-Li Xie, Guang-Yi Wang
• Format: Article
• Language: English
• Published: Ivyspring International Publisher 2012-01-01
• Series: International Journal of Medical Sciences
• Online Access: http://www.medsci.org/v09p0216.htm

<p>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 (&#916;&#936;m). 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 (<i>P</i> &#60; 0.05), which was further enhanced in cells targeted for both molecules (<i>P</i> &#60; 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.</p>