Abstract: Objective To study the expression and significance of phosphorylated p38 (p-p38) and uPA in breast cancer tissues and cells. Methods Immunohistochemistry (S-P) was used to test the protein expression of p-p38 and uPA in 60 specimens excised during operation from 50 patients with breast cancer. Western blotting was adopted to detect the protein expression of p-p38 and uPA in breast cancer cells and uPA protein expression after SB203580, an specific inhibitor of p38 MAPK blocked p38MAPK signaling pathway. Results The positive rate of p-p38 protein and uPA protein in breast cancer tissues was 56.7%and 60.0%,respectively. The protein expression levels of p-p38 and uPA in breast cancer tissues were significantly higher than those in the adjacent normal tissues(P<0.05) The protein expression of p-p38 was linearly correlated with uPA expression(r=0.316, P<0.05). The expression of p-p38 and uPA was related to lymph node metastasis and TNM stage (P<0.05), and it was not related to patients'age and tumor size. The protein expression levels of p-p38 and uPA in breast cancer cells MDA-MB-231 were higher than that in MCF-7. SB203580 nhibited p38MAPK pathway and down-regulated uPA protein expression. Conclusion Overexpression of p-p38 and uPA may play a critical role in breast cancer malignant progression. These results provide instructive clues to breast cancer invasion and metastasis research.

Key words: p-p38 uPA Breast cancer