ABSTRACT
Objective To study the relationship between the expression of p53 and its downstream effecter p21~(waf1)protein and multi-drug resistance(MDR) of Tca8113/BLM cell line.Methods The cDNA of wildtype p53 gene was introduced into the drug-resistance cell line Tca8113/BLM by Lipofectamine-mediated transfection.The expression of p53 mRNA in Tca8113/BLM and its parental counterpart Tca8113 cell lines were analyzed using molecular beacons.The expression of p53,p21~(waf1),P-gp,and MRP proteins in Tca8113/BLM cell line transfected by wt-p53 cDNA,the untransfected control Tca8113/BLM cell line,its parental counterpart Tca8113 were analyzed by Western blotting.MTT assay was used to determine the drug-sensitivity of different cell lines.The cell cycle distribution and apotosis of different cell lines were also observed by flow cytometery(FCM) and laser confocus microscope(LCM),respectively.Results The expression of p53 protein was significantly lower,and no p21~(waf1) protein was detected in Tca8113/BLM cells.The protein expression of P-gp and MRP were significantly higher in Tca8113/BLM cells than in Tca8113 cells.By Western Blotting,the expression of p53 and p21~(waf1)proteins was significantly increased,while the expression of P-gp and MRP proteins was significantly decreased in Tca8113/BLM/p53 cells.Comparing to Tca8113/BLM cells,the sensitivity of BLM treatment in Tca8113/BLM/p53 cells was 10.1 fold increased.Tca8113/BLM/p53 cells decreased at G1 and S phase,and increased at G2 phase.LCM results showed that the apoptosis of Tca8113/BLM/p53 cells was more obvious than Tca8113/BLM cells when treated with the drug BLM.Conclusion The multi-drug resistance in Tca8113/BLM cell line is involved in down-regulation of p53 and p21~(waf1) protein levels,and up-regulation of P-gp and MRP protein levels.