ABSTRACT
Objective To investigate the relationship of STAT3 with expressions of MMP-2,MMP-9 and TIMP-1 and with epithelial-mesenchymal transition (EMT) in breast cancer cells,and to explore the clinical significances.Methods The mRNA of STAT3 and the protein expressions of pSTAT3,MMP-2,MMP-9 and TIMP-1 of breast cancer cells in 84 patients with breast cancer were determined by real-time RT-PCR technique and immunohistochemical method in paraffin-embedded specimensm respectively.Normal breast tissues adjacent to breast cancer were taken as controls.Results mRNA expression of STAT3 was significantly higher in breast cancer tissues than in controls (t=4.513,P＜ 0.001).Protein expressions of pSTAT3,MMP-2,MMP-9 and TIMP-1 were higher in breast cancer tissues than in controls (all P＜ 0.05).There were positive correlations between pSTAT3 expression and the expressions of MMP-2,MMP-9 and TIMP-1 in breast cancer tissues (all P＜0.05).The higher levels of pSTAT3 and MMP-2 were associated with poorer differentiation and more lymph node metastasis of breast cancer (both P＜0.05).The positive expression of MMP-9 was correlated with lymph node metastasis (P＜0.05),but not with histological grading (P＞0.05).The positive expression of TIMP-1 had no associations with histological grading and lymph node metastasis (both P＞0.05).There were no significant differences in the protein expressions level of pSTAT3,MMP-2,MMP-9 and TIMP-1 between different ages and different breast tumor sizes (all P＞0.05).Conclusions The increased expression of STAT3 in breast cancer cells is closely correlated with the increased expressions of MMP-2,MMP-9 and STAT3 inhibitor TIMP-1.The activation of STAT3 gene can mediate EMT by inducing the protein expressions of MMP-2,MMP-9,which promotes the invasion and metastasis of breast cancer.