Difference of Drug-Resistance between Single-Factor Resistance Cell Line K562/MDR1 Transfected with mdr1 Gene and Multi-Factor Resistance Cell Line K562/A02 Induced by Doxorubicin.

Objective To study difference of drug-resistance between single-factor resistance cell line K562/MDR1 transfected with mdr1 gene and multi-factor resistance cell line K562/A02 induced by doxorubicin.

Methods Retroviral virions carrying the complete sequence of mdr1 gene cDNA were produced and infected drug-sensitive leukemia cell line K562 and mdr1 single-factor resistance cell line K562/MDR1 was established. The difference of drug-resistance between K562/MDR1 and K562/A02, a kind of multi-factor resistance cell line induced by doxorubicin, was studied by checking the expression of mdr1 gene and Pgp, daunorubicin efflux rate, MTT drug sensitivity to chemotherapeutic drug. Lentiviral vector encoding shRNA which targeted MDR1 gene was transfected into two kinds of cell lines and effect of RNAi on reversing drug resistance was detected.

Results The results of Q-PCR and flow cytometry demonstrated that there were high expression of mdr1 mRNA and Pgp in both kinds of drug-resistance cell lines and no difference between them. The function of Pgp detected by daunorubicin efflux rate is higher in K562/MDR1 (90.93%) than K562/A02 (78.67%). The results of MTT test showed that IC₅₀ of K562/MDR1 and K562/A02 is 0.55 and 1.22μmol/L respectively and this confirmed that drug-resistance in K562/A02 is higher than that in K562/MDR1. After RNA interference, the expression of the mdr1 gene and Pgp in K562/MDR1 markedly was down-regulated and the drug resistance was restored and IC₅₀ is 0.16μmol/L, similar to K562 sensitive cell line. The expression of the mdr1 gene and Pgp in K562/A02 markedly was downregulated too, and drug resistance to anticancer drug is reduced to some extent but IC₅₀ is 0.56μmol/L, it is still higher than that in sensitive cell line.

Conclusion Drug-resistance in K562/A02 induced by anticancer-drug was made of many factors and it is more resistance to anticancer-drug than that in K562/MDR1 caused by mdr1 gene. Due to only mdr1 resistance, K562/MDR1 is better cell model to make mdr1/Pgp research.