Survivin downregulation by siRNA/cationic liposome complex radiosensitises human hepatoma cells in vitro and in vivo.

PURPOSE: To investigate the effect of survivin-short hairpin RNA (shRNA) on the proliferation, apoptosis and radiosensitivity of human hepatoma SMMC-7721 cells.

MATERIALS AND METHODS: Survivin-targeted small interfering RNA (siRNA) expression vector was constructed and transfected into SMMC-7721 cells mediated by cationic liposome. Survivin mRNA and protein expression were analysed by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting. Cell viability was measured by 3-(4, 5-dimethylthiazol-2-yl)- 2, 5-diphenyl tetrazolium bromide (MTT) assay. Cell cycle and apoptosis were measured by flow cytometry (FCM) assay. Radiosensitivity of SMMC-7721 cells was examined using a colony-forming assay. Mice subcutaneously implanted with SMMC-7721 cells were monitored for tumour growth and survival after treatment, and tumours were analysed for proliferation, apoptosis, and angiogenesis biomarkers by immunohistochemistry staining.

RESULTS: After transfection, the mRNA and protein expression of survivin gene in SMMC-7721 cells downregulated, which led to significant cell growth inhibition, cell arrest in G2/M phase, increased apoptotic rate and radiosensitivity. Survivin-shRNA in combination with radiotherapy was more effective than radiotherapy or survivin-shRNA therapy alone in suppressing tumour growth and extending survival duration. Combined therapy inhibited cell proliferation and tumour angiogenesis and increased apoptosis in tumour xenografts.

CONCLUSION: Survivin downregulation by siRNA/cationic liposome inhibited proliferation, induced apoptosis and enhanced radiosensitivity in human hepatoma cells in vitro and in vivo.