Effect Of HMLH1 Gene On Cisplatin Sensitivity Of Drug-Resistant Human Ovarian Cancer Cell Line

Objective To explore the reversing effect of hMLH1 mismatch repair gene on cisplatin resistance in ovarian cancer cell line SKOV3/DDP and its possible mechanismMethods (1) Eukaryotic expression plasmid pcDNA3.1-hMLH1 or pcDNA3.1 empty vector was transfected into SKOV3/DDP cells transiently with lipofectamine 2000, SKOV3 and non-transfected SKOV3/DDP cells served as controls. Expression levels of hMLH1 mRNA and protein were detected by RT-PCR and Western blot. The growth inhibition of cisplatin(3.0,6.0,12.0,24.0,48.0μg/ml)on SKOV3/DDP cells was assayed by MTT.(2) After treatment with cisplatin(6μg/ml) for 24h, cells apoptosis were detected by flow cytometry (FCM) and Hochest dyeing.The expression level of bcl-2 protein was determined by Western blot.Results After transiently transfected with hMLH1 gene for 24 hours, the expression levels of hMLH1 mRNA and protein were increased significantly. MTT assay showed the IC50 value for cisplatin was obviously lower than the non-transfected SKOV3/DDP cells, chemosensitivity of transfected SKOV3/DDP cells to cisplatin was enhanced. FCM and Hochest dyeing showed that the apopototic rate of SKOV3/DDP cells transfected with hMLH1 gene was increased. The expression of bcl-2 in hMLH1 transfected cells was decreased in the course of apoptosis when treated with DDP.Conclusion The hMLH1 gene which successfully transfected into SKOV3/DDP cells can increase the chemosensitivity of cells to cisplatin ,induce the apoptosis and reverse the drug resistance of SKOV3/DDP cells to cisplatin to a certain extent which may be related to the down-regulation of bcl-2 expression.