Development of a real-time fluorescence quantitative PCR method for detection of FPGS mRNA expression in methotrexate enantiomer-resistant A549 cell lines and patients with leukemia

Abstract

Objective To establish a real-time fluorescence quantitative PCR method for detection of the different expression level of FPGS in methotrexate enantiomer-resistant A549 cell lines,and observe FPGS mRNA expression in patients with leukemia.Methods A real-time fluorescence quantitative PCR method for detection FPGS mRNA was established using SYBR Green Ⅰ as fluorescence and β-actin as reference.The method was evaluated by Ct,correlation coefficient,slope,repeatability curve,melting curve and amplification efficiency curve.The expression levels of FPGS gene in methotrexate enantiomer-resistant A549 cell lines and methotrexate resistant leukemia cells in bone marrow were detected by the method.Results The standard curves had a high linear relationship between cycle threshold and template concentration.The correlation coefficients of FPGS and β-actin were 0.996 8 and 0.998 7,and the slopes were -3.595 and -3.740,respectively.The inter-coefficient of variation was from 1.27% to 2.95%.The intra-coefficient of variation was 3.82%.The method was characterized with specific melting curve and similar amplification efficiency(slope was 0.021 7).The relative contents of FPGS mRNA were(3.51 ±0.66),(0.16 ±0.01) and(1.00 ±0.31) in L-(+)-MTX/A549 cells(L),D-(-)-MTX/A549 cells(D)and A549 parent cells,and there was statistically difference among the three groups(F = 64.45 ,P＜ 0.01)Statistical difference was observed between L and D(q =9.29,P＜0.01).After treated with MTX,the expression level of FPGS mRNA was(0.35 ± 0.04) in methotrexate resistant leukemia patients,compared with(1.00 ± 0.44) before treatment.Statistical difference was observed(t = 8.83 ,P＜ 0.01).Conclusions The real-time fluorescence quantitative PCR is suitable for the quantification of FPGS.The expression levels of FPGS in methotrexate resistant leukemia cells in bone marrow and drug resistant cells are different.Two enantiomer forms of methotrexate may play different roles in drug resistance mechanisms. Key words: Cell line,tumor; Leukemia; Methotrexate; Peptide synthases; Drug resistance,neoplasm; Polymerase chain reaction; Stereoisomerism