RESUMEN
[Objective]To study the difference in expression of RFC, GST-?, DHFRmRNA between human osteosarcoma U2-OS cell line and the MTX-resisitant variants U2-OS/R1-R3, and to investigate the significance in MTX resistance for human osteosarcoma. [Methods]Three resistant MTX human osteosarcoma cell lines were established by pulse exposure parental cell line(U2-OS) in gradually increased dose of MTX . The expression of RFC,GST-?,DHFRmRNA were assayed by real-time fluorescence quantitative polymerase chain reaction(FQ-PCR).[Results]Three MTX-resistant variants(U2-OS/R1-R3) were successfully established , the results of the FQ-PCR revealed that the MTX resistance was associated with the decreased expression of the RFC mRNA and increased expression of DHFR mRNA and GST-? mRNA.[Conclusion]The author investigated the MTX resistant mechanism of human osteosarcoma cell line at a gene level. The decreased expression of RFC mRNA and the increased expression of DHFR mRNA and GST-? mRNA participate in the MTX resistance in human osteosarcoma cell lines U-2 OS. This provides the evidence for exploring the MTX resistance mechanism in clinical osteosarcoma patients ,and helps to screen the patients who are insensitive to MTX chemotherapy.