Establishment Of Nude Mice Xenografts Of MTX Enantiomers-resistant A549 Cells

Background An enantiomer is one of two stereoisomers that are non-superposable complete mirror images of each other, much as one's left and right hands are"the same"but opposite. Many molecules in the bodies of living beings are enantiomers themselves, such as DNA, proteins,there is often a marked difference in the effects of two symmetrical enantiomers on living beings. Methotrexate, one of chiral drugs, has two monomer forms, L-MTX and D-MTX. It was widely used in tumor therapy as classical antifolate. But acquired drug-resistance was common in clinical MTX application. According to the feature of enantiomers and conclusions of our experiments in vitro, the ratio of L-MTX and D-MTX in commercial praeparatum can impact on therapeutic effect and degree of drug-resistance. It is necessary to build tumor animal models to analyze the anti-tumor difference of L-MTX and D-MTX.Objective To establish a nude mice xenograft model of MTX enantiomers-resistant human lung carcinoma A549 for exploring the mechanism of tumor proliferation and drug-resistanceMethods Two drug-resistant cell lines, A549/L-MTX, A549/D-MTX were transplanted into nude mice subcutaneously in right flank. The parent A549 cells were transplanted as control. Tumor growth activities and xenografts'resistance index were compared. The expression of proliferation marker ki-67, multi-drug resistance-associated protein 1 (MRP1) and apoptosis inhibitor survivin were assessed by RT-PCR and immunohistochemistry.Results Tumor volume of A549/L-MTX/nude grew smaller than that of A549/D-MTX/nude, and the tumor ki-67, MRP1 and survivin expression of A549/L-MTX/nude decreased ( P<0.05). Low drug-resistance (RI=4.9) in A549/L-MTX/nude tumor and medium drug-resistance (RI=14.5) in A549/D-MTX/nude tumor were shown.Conclusions Nude mice xenografts of MTX enantiomers-resistant A549 cells were established and retained the characteristics of tumor drug-resistance phenotype, but appearanced different enantiomers'effects on tumor proliferation, apoptosis and degree of drug-resistance. This provides an ideal animal model for future study of MTX enantiomers.