Objective:Studies have shown that TNF-α secreted by tumor cells and macrophages infiltrated in the tumor microenvironment may promote the metastasis of a variety of malignant cancers,including breast cancer. The present study was designed to detect global metastasis related gene expression changes of MCF-7 cells treated by low dose TNF-α(20 ng/ml),and to explore the mechanisms of TNF-α-induced metastasis. Methods:Transwell assay was used to investigate the invasion capability. cDNA array analysis was applied to detect the metastasis related gene expressions. Results:The invasive ability of MCF-7 cell was enhanced by low dose TNF-α. There were 39 gene expressions significantly changed after treatment of TNF-α. There were 6 genes which have not been reported to be regulated by TNF-α. Most of these genes promoted the metastasis of MCF-7 cells while the others inhibited. The gene expressions induced by TNF-α were somewhat time-dependent. Conclusions:TNF-α can enhance the invasive ability of MCF-7 cells by regulation of metastasis related genes,which may take part in every step of metastasis. Further study on some of the genes is needed.