[Analysis of the multidrug resistance MDR1 gene expression in clinical leukemia with RT-PCR]

The method of reverse transcription coupled with polymerase chain reaction (RT-PCR) has been used to detect multidrug resistance gene MDR1 expression in 73 leukemia patients. Specificity of MDR1 PCR product was identified by a probe labelled with biotin. In this paper, beta 2M mRNA (a 120bp of PCR product) was selected as an internal control for semi-quantitative analysis of MDR1 mRNA (a 157bp of PCR product). Detection of MDR1 expression was positive in 31 of the 73 patients with leukemia. The percentage of MDR1+ and the value of MDR1/beta 2M in the relapsed acute leukemia and CML in blast crisis were 76.00% and 0.798 +/- 0.266, they were significantly higher than those in newly diagnosed acute leukemia (25.00% and 0.386 +/- 0.128) and complete remission leukemia (25.00% and 0.151 +/- 0.059), MDR1/beta 2M in newly diagnosed was significantly higher than that in complete remission. We found that MDR1 gene expression correlated well with response to chemotherapy in 53 cases of acute leukemia. The refractory rate in patients with MDR1+ was 75.00%, while it was 15.00% in MDR1- (P < 0.01). We thought that the determination of MDR1 expression level in acute leukemia could provide a valuble information for designing chemotherapeutic regimen in individual patient, and a high level of MDR1 expression correlated closely with drug resistance in clinical leukemia chemotherapy.