Effective inhibition of hTERT expression by RNA interference on the radiosensitivity of human laryngeal cancer Hep-2 cell line / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To construct an eukaryotic expression vector of human telomerase reverse transcriptase (hTERT) gene specific shRNA, and investigate the effect of pshRNA-hTERT combined with gamma-irradiation on cell survival and telomerase activity.</p><p><b>METHODS</b>According to the coding sequence of hTERT mRNA, the target of RNAi was designed, and recombinant expression plasmid pshRNA-hTERT was constructed. The vector was transfected into Hep-2 cells. The radiosensitivity of Hep-2 cells was determined by clonogenic assay. Telomeric repeat amplification protocol (TRAP-PCR-ELISA) was used to observe the telomerase activity in each group. Results Recombinant expression vector pshRNA-hTERT was successfully transfected into Hep-2 cells. The hTERT expression inhibition rate reached 60. 8%. pshRNA-hTERT not only inhibited telomerase activity of Hep-2, but also inhibited the raise of telomerase activity induced by gamma-irradiation. Exposure of Hep-2 cells to pshRNA-hTERT for 24 hrs before irradiation resulted in a decrease in mean surviving fraction of Hep-2 cells compared with cells of group with irradiation alone (67. 7% vs 85. 7%, P <0. 05) .</p><p><b>CONCLUSION</b>RNAi showed a significant inhibitory effect to the expression of hTERT. The results indicate that pshRNA-hTERT can effectively inhibit telomerase activity of Hep-2 cells treated or untreated with 2 Gy gamma-irradiation and significantly enhance the radiosensitivity of Hep-2 cells in vitro. The role of radiosensitization of pshRNA-hTERT may be related with the inhibition of telomerase activity.</p>

Apoptosis induced by short hairpin RNA-mediated STAT6 gene silencing in human colon cancer cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The relationship between signal transduction and tumors has become one of the foci in cancer research. Signal transducer and activator of the transcription 6 (STAT6) signaling pathway is found to be activated in some cancer cells. But the function of the pathway in cancer cells is unknown. This study was undertaken to investigate the effect of the Stat6 signaling pathway on apoptosis in human colon cancer cells (HT-29 cells) and the possible mechanism of Stat6 by RNA interference techniques.</p><p><b>METHODS</b>Four eukaryotic expression plasmid vectors of short hairpin RNA (shRNA) specific for the STAT6 gene were designed and generated by molecular biological technology. The plasmid vectors were transfected into HT-29 cells by cation liposomes to block the Stat6 signaling pathway. The expressions of STAT6 mRNA and phosph-Stat6 protein were detected by the reverse transcriptase polymerase chain reaction (RT-PCR) method and flow cytometry respectively to screen the most effective shRNA at 72 hours after transfection. The apoptosis condition of the cells in which the expression of the STAT6 gene had been interfered was analyzed by flow cytometry and confocal microscopy. Both mRNA and protein expression of B cell lymphoma-2 (Bcl-2) and Bax were detected by RT-PCR and western blotting.</p><p><b>RESULTS</b>Two effective eukaryotic expression plasmid vectors of shRNA specific for the STAT6 gene were generated successfully. One can reduce the expression of the STAT6 gene by 82.4% and the other by 56.8% (P < 0.01). The apoptotic rate of colon cancer cells in which STAT6 gene expression had been interfered was significantly higher than that in controlled colon cancer cells (P < 0.01). In the cells in which the Stat6 signaling pathway was blocked, the levels of mRNA and protein Bcl-2 were significantly decreased, whereas those of Bax were significantly increased (P < 0.01).</p><p><b>CONCLUSIONS</b>The Stat6 signaling pathway can inhibit apoptosis in human colon cancer cells. The subsequent disorder of Bcl-2/Bax expression may play an important part in that process. The STAT6 gene may serve as a potential target in cancer therapy.</p>