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.