The Up-regulation Expression of DNMT3a Resensitizes A549 Cell to Cisplatin

Abstract: The change of gene methylation status is a main cause for acquired chemo resistance of cancer. DNMTs plays an indispensable role in methylation regulations. In order to find a biomarker predicting chemo sensitivity of A549 cell to cisplatin， human lung adenocarcinoma A549 cells were chosen and transfected with a DNMT3a plasmid to enhance the expression of DNMT3a. Semi-quantitative RT-PCR was performed to confirm the expression of DNMT3a mRNA before and after plasmid transfect. Exposing to different concentrations of cispaltin， MTT assays were used to evaluate cell viability and calculate the IC50 value to cisplatin before and after plasmid transfect respectively; clone formation assay were detected to evaluate the clone forming ability before and after cell transfect. Exposing to the same concentration of cisplatin， flow cytometric analysis was used to assess apoptosis rate before and after plasmid transfect. The results indicated: exposing to cisplatin 24 h， IC50 value to cisplatin increased greatly in A549 cell with exogenous expression of DNMT3a than that in A549 cell [(9.19±0.91) μmol/L vs (4.96±0.58) μmol/L， P=0.000]. After exposing to cisplatin for 5 days， the clone number of A549 with exogenous expression of DNMT3a was significantly increased than that of A549; with the same concentration of cisplatin， the apoptosis percentage decreased greatly in A549 with exogenous expression of DNMT3a than that of A549 [(1.33±0.38)% vs (5.22±0.67)%， P=0.039]. The results suggest that the up-regulation expression of DNMT3a may be a vital cause for acquired chemo resistance of lung cancer and it needs deeply study about serum DNMT3a acts as biomarker and a predictive factor for chemosensitivity of lung cancer patients in clinic.

CSTR: 32200.14.cjcb.2013.07.0014