title: Effects of STAT3 gene silencing and rapamycin on apoptosis in hepatocarcinoma cells.
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.
authors.affiliation: Department of Hepatobiliary and Pancreatic Surgery, the First Hospital of Jilin University, Changchun, 130021, P. R. China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jun-Wei
authors.initials: JW
authors.lastname: Zhang
authors.forename: Guo-Yue
authors.initials: GY
authors.lastname: Lv
authors.forename: Shu-Li
authors.initials: SL
authors.lastname: Xie
authors.forename: Guang-Yi
authors.initials: GY
authors.lastname: Wang
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000473:pathology / Q000628:therapy*; D045744:Cell Line, Tumor; D020868:Gene Silencing; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology / Q000628:therapy*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D034622:RNA Interference; D050796:STAT3 Transcription Factor / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D020123:Sirolimus / Q000627:therapeutic use*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus