Simultaneous detection of WT1 and MDR1 gene expression in acute leukemia patients by a multiplex real time quantitative PCR method / 中华检验医学杂志

ABSTRACT

Objective To set up a multiplex real time quantitative PCR method to detect the expression of WT1 and MDR1 gene simultaneously in acute leukemia patient. Methods Total RNA was extracted from k562 cell line and was reverse transcribed to cDNA by the outer primers of WT1 and MDR1 respectively. The cDNA of WT1 and MDR1 were purified and digested by Bam H Ⅰ and Bgl Ⅱ , and then the two fragments were ligated to form the recombinant fragment WT1 + MDR1. The outer forward primer of WT1 and outer reverse primer of MDR1 were used to amplify the recombinant fragment WT1 + MDR1. The PCR product was purified and cloned into pMD18-T vector, and then transferred into E. coli DH-5α. A new kind of WT1-MDRl-contained standard plasmid was obtained from the positive colony. The recombinant plasmid was verified by digestion with restriction enzyme and PCR amplification. A multiplex real time quantitative PCR method was set up with FAM-labeled MDR1 probe and VIC-labeled WT1 probe in one reaction tube. The WT1 and MDR1 gene expression was detected in forty-seven AL patients and thirty-two controls by this method. Seven patients were followed-up to elucidate the relationship between the gene expression levels and clinical prognosis. Results The recombinant plasmid was confirmed by EcoR1 digestion and PCR amplification. The multiplex real time quantitative PCR technique could reach the sensitivity of WT1 and MDR1 gene up to 102 copy/μl. The standard curve slopes were 0. 999 and 0. 998. The WT1 [ 37 000( 163-6 370 000 )copies/μg RNA ] and MDR1 [ 76 200( 179-18 000 000 )copies/μg RNA ]expression levels of AL patients were significantly higher as compared to the controls [ 258( 0-643 ) copies/μg RNA and 333( 0-779 )copies/μg RNA ]( Z= 6. 755,6. 736, P ＜ 0. 01 ). Following up seven patients with similar regimen of chemotherapy, the WT1 and MDR1 expression correlated to the clinical course. Three AL patients with WT1 and MDR1 expression levels (2 170 and 86 900, 1 130 and 5 860, 1 170 and 586 copies/μg RNA )significantly decreased after chemotherapy and kept in the low range ( 370 and 560,138 and 980, 150 and 690 copies/μg RNA ), and had a favorable outcome. Three AL patients with WT1 and MDR1 expression levels ( 1 600 and 11 800, 24 800 and 968, 48 200 and 1 100 000 copies/μg RNA )decreased after initial chemotherapy, but increased significantly afterwards (20 314 and 25 660,184 364 and 31 530, 15 680 and 878 000 copies/μg RNA ),and suffered clinical relapse. One patient with high WT1 and MDR1 expression levels ( from 81 600 and 1 200 000 copies/μg RNA to 124 100 and 7 632 400 copies/μg RNA )showed the persistence of disease. Conclusions A multiplex real time quantitative PCR method to detect WT1 and MDR1 gene simultaneously is constructed successfully. The expression of WT1 and MDR1 may provide useful information for AL patients prognosis.