RESUMO
Tumor recurrence and drug resistance impact patients'therapeutic effect and prognosis seriously.In recent years,it has been found that epigenetic changes are involved in drug resistance.DNA methylation is one of the ways of epigenetic.DNA methylation of drug metabolism enzyme gene can affect gene's expression,leading to drug resistance.Methotrexate(MTX),a folic acid antagonist,is the most widely used drug in the treatment of malignant tumors,such as leukemia,osteosarcoma,head and neck cancer,and so on.Reduced folate carrier(RFC) is the main transporter cartier of MTX,and gene methylation is related to tumor cells'resistance to MTX.This paper reviews the role of RFC,relation of RFC methylation and methotrexate resistance and the factors of RFC methylation.