Abstract: Rad51 is the central molecule of homologous recombination (HR), which assembles on ssDNA as an oligomeric nucleoprotein filament and then invades the homologous double'stranded DNA during chromosome pairing to complete the repairing of DNA damage through different downstream pathways. The role of Rad51 in malignant tumors is mainly to promote tumor development, metastasis and anticancer drug resistance, including: (1) The interactions between Rad51 and cycle checkpoint molecules play a regulatory role in related pathways to affect tumor development and metastasis. (2) The reduced expression of Rad51 leads to partial reversal of epithelial mesenchymal transformation(EMT) process to regulate EMT'related metastasis and drug resistance of tumor cells. (3)The relationship between Rad51 and drug resistance of tumor can be revealed through gene polymorphism studies. (4) A number of microRNAs and long non'coding RNAs targeting the coding region of Rad51 can regulate gene expression and ultimately regulate HR efficiency and the development of drug resistance of tumor cells. Recently, the mechanisms above have been identified by the reports of Rad51 overexpression in ovarian, breast and lung cancer, which indicates that the over'expression of Rad51 is related to metastasis and drug resistance of malignant tumor. The regulation of Rad51 expression can reverse the process of tumor drug resistance, and it is expected to become a novel target for the treatment and drug resistance of cancer.

Key words: Malignant tumor')">">, Rad51')">">, Homologous recombination')">">, Tumor metastasis')">">, Drug resistance