Effect Of Silencing TGF-β1with Small Interfering RNA On Cisplatin Resistance Of Lung Cancer Cells

Objective The corr-elation between epithelial-mesenchymal transition (EMT) and chemoresistance in non-small cell lung cancer (NSCLC) has been confirmed by our previous experiments and some other reseach. This experiment took the main regulator of EMT-transforming growth factor-β1(TGF-β1), as the starting point to explore the effect of small interfering RNA (siRNA) on chemoresistance of A549/DDP cells, and to further investigated the mechanisms of cisplatin-resistance.Methods The mRNA and protein expression of E-cadheim、vimentin and ERCC1were investigated by RT-PCR and immunocytochemistry of A549/DDP cells transfected with TGF-β1siRNA. The mortality and sensitivity to cisplatin of cells was observed by cck-8assay in different group retreated with cisplatin.Results1. We observed that A549/DDP assumed a spindle shape, and arranged in a spiral or radial shape. This observation was further supported by expression of EMT marke by RT-PCR:E-cadherin of A549/DDP cells were down regulated and the vimentin of which were up regulated, which consistent with the EMT phenotype;2. Knockdown of TGF-β1in A549/DDP cells resulted in a significant increase in the expression of E-cadherin, and down regulation of vimentin and ERCC1;3. We observed the changes of drug resistance index and sensitivity to cisplatin of A549/DDP cells after transfection by cck-8assay, finding that the drug resistance index of A549/DDP cells group was2.77, and that of transfected group was1.28, there was significant difference in the two groups (P=0.000). The inhibition rate at24h、48h、72h of cisplatin in A549/DDP transfected group was increased significantly compared with A549/DDP group (P=0.000), and there was no significant difference in the control group(P>0.05).Conclusion1. A549/DDP cells acquired cisplatin-resistance and occurred EMT simultaneously. The expression of epithelial phenotype marker of A549/DDP cells was enhanced and the expression of resistance factor-ERCC1was reduced after TGF-β1-siRNA transfection. It indicated that targeting silence TGF-β1can reverse the EMT progress of A549/DDP cells.2.We confirmed that inhibit the expression of TGF-β1can restore the sensitivity to cisplatin of A549/DDP cells by cck-8assay. It suggested that reverse the EMT can enhance the sensitivity to cisplatin of A549/DDP cells effectively. It further confirmed the correlation between TGF-β1-mediated EMT and chemoresistance of tumor cells.