Effects Of Silencing STAT3 Gene With SiRNA On HepG₂ And SMMC-7712 Hepatocarcinoma Cell Lines

Hepatocarcinoma is one of the common malignant tumors which threatening human`s life, and its happening and progressing are affected by many different factors. The curative effects of raditional radiotherapy, chemotherapy and surgery are not satisfactory. So gene therapy becomes the research focus of hepatocarcinoma therapy. Signal transducers and activators of transcription (STATs) are a cytoplasmic protein family, which were first found during the research of gene trascription induced by interferon (IFN). Recent research has found that STATs, especially STAT3 could inhibit cell apoptosis, promote cell proliferation, and involved in the happening and proceeding of various human malignent tumors. STAT3 signal transduction pathway is relative to the cell proliferation, differentiation and apoptosis, its continuous activiation would cause abnormal proliferation and malignant transformation of cells, so it has been defined as an onco-gene. RNA interference (RNAi) is an important post-transcriptional gene silencing mechanism discovered in recent years, which can trigger the post-transcriptional monitoring process and degrade the specific single chain mRNA. In present study, small hairpin RNAs (shRNA) targeting STAT3 were designed and cloned into vector pGenesil-1, and liver cancer cell lines of HepG2 and SMMC-7721 stably expressing shRNA were selected out. The specific post-trascriptional silencing effects of these siRNA on STAT3 gene in liver cancer cell HepG2 and SMMC-7721 were detected in vitro. Our research would explore a new method for liver cancer gene therapy.Objective: To study the effects of silencing signal transducers and activatiors of transcription 3 (STAT3) with RNA interference (RNAi) technique on the proliferation and apoptosis in HepG2 and SMMC-7721 hepatocarcinoma cell lines.Methods: Three recombinant plasmids pGenesil-1-shRNA-STAT3 were constructed and transfected into HepG2 and SMMC-7721 cells. The expressions of STAT3 gene were detected by RT-PCR and Western blot. MTT and flow cytometry (FCM) were used to determinant the change of cell proliferation and generation cycle of HepG2 and SMMC-7721 cells.Results: Three pGenesil-1-shRNA-STAT3 recombinant plasmids were successfully constructed, and transfected into HepG2 and SMMC-7721 cells. RT-PCR and Western blot analysis demonstrated that pGenesil-1-shRNA-STAT3 could significantly inhibit the mRNA and protein expressions of STAT3 in HepG2 and SMMC-7721 cells. MTT and FCM results showed that targeting STAT3 shRNAs could significantly suppress the proliferation and induce the apoptosis of HepG2 and SMMC-7721 cells.Conclusion: Silencing of STAT3 with shRNA could significantly inhibit STAT3 expression, suppress the growth and induce the apoptosis of HepG2 and SMMC-7721 cells.