Relationship between Methylation Status of Multi-drug Resistance Protein (MRP) and Multi-drug Resistance in Lung Cancer Cell Lines

Objective: To study the relationship between the methylation status of multi-drug resistance protein (MRP) gene and the expression of its mRNA and protein in lung cancer cell lines. Methods:Human lung cell line WI-38.lung adenocarcinoma cell line SPCA-1 and its drug-resistant cells induced by different concentrations of doxorubicin were treated with restriction endonuclease Eco47III.The methylation status of MRP was examined by PCR,and the expressions of its mRNA and protein were evaluated by in situ hybridization and immunohistochemistry. Resuits: MRP gene promoter region of WI-38 cells was in hypermethylation status.but the promoter region of MRP in SPCA-1 cells and their resistant derivatives induced by different concentrations of doxorubicin were in hypomethylation status.There were Significant differences in the expression of MRP mRNA among WI-38 cell line.SPCA-1 cells and their drug-resistan t derivatives induced by different con- centration of doxorubicin.Consistently.MRP immunostaining presented similar significant differences. Conclusion:The promoter region of MRP in SPCA-1 lung adenocarcinoma cells was in hypomethylation status. The hypomethylation status of regulatory region of MRP promoter is an important structural basis that can increase the activity of transcrip-tion and results in the development of drug resistan cc in lung cancer.