Objective:This study investigated the expression and biological role of toll-like repeptor-4 (TLR4) in human breast cancer proliferation and metastasis. Methods:Lipopolysaccharide (LPS) was used to stimulate MCF-7,expression of TLR4 mRNA and protein was analyzed by RT-PCR,Real-time PCR,FCS and Western blotting;MMP-2,MMP-9 and VEGF were measured by RT-PCR and Real-time PCR on the mRNA levels and ELISA on the protein levels;MyD88 was analyzed by Western blotting;The cytokines in the supernatants were measured by CBA;The cell proliferation was analyzed by MTT;The invasion was analyzed by wound healing assay. Results:Using LPS to stimulate MCF-7,TLR4 mRNA and protein increased obviously. However,the proliferation had no significant changes. In addition,the activation of TLR4 promoted the expression of MMP-2,MMP-9 and VEGF notablely. LPS promoted the invasion of MCF-7. Moreover,the stimulation of LPS significantly increased the expression of MyD88,and caused the secrection of IL-6. Conclusion:This study indicated that TLR4 may participate in the progression and metastasis of human breast cancer.