HER-2/neu and urokinase-type plasminogen activator and its inhibitor in breast cancer

Purpose: Recent studies suggest that HER-2/neu specifically promotes the in vasive capacity of tumor cells by upregulating secretion of the proteolytic enzyme, urokinase-type plasminogen activator (uPA), or its inhibitor, plas minogen activator inhibitor-1 (PAI-1), in colon and gastric cancer. It was the purpose of this study to: (a) evaluate the association between HER-2/ne u and uPA and PAI-1 expression in a large primary breast cancer cohort; (b) perform the first multivariate analysis, including HER-2/neu, uPA, and PAI -1 in breast cancer; and (c) define the effect of HER-2/neu overexpression on uPA and PAI-1 expression in breast cancer cells. Experimental Design: HER-2/neu, uPA, and PAI-1 were measured as continuous variables by ELISA in primary breast cancer tissue extracts from 587 patien ts with clinical follow-up and analyzed for correlations with clinical outc ome. Furthermore, a full-length human HER-2/neu cDNA was introduced into fi ve human breast cancer cell lines to define the effects of HER-2/neu overex pression on uPA and PAI-1 expression. In addition, we tested whether HER-2/ neu antibodies could reverse any given alteration of uPA and PAI-1 levels. Results: Our findings indicate a weak positive association between HER-2/ne u and uPA (r = 0.147; P < 0.001) and no association between HER-2/neu and P AI-1 (r = 0.07; P = 0.085). HER-2/neu overexpression (greater than or equal to 400 fmol/mg) and high levels of uPA/PAI-1 (greater than or equal to 5.5 ng/mg and/or greater than or equal to 14 ng/mg, respectively) were signifi cantly associated with shorter disease-free survival (DFS; P < 0.001 and P = 0.003) and metastasis-free survival (MFS; P = 0.015 and P < 0.001). Multi variate analysis revealed prognostic independence between HER-2/neu and the uPA/PAI-1 axis for DFS and MFS. Both uPA and PAI-1 had no significant disc riminatory effect among HER-2/neu-positive patients for DIPS. The prognosti c value of HER-2/neu overexpression for MFS, however, was significantly enh anced by elevated uPA expression (P = 0.053). Stable transfection of the HE R-2/neu gene into multiple human breast cancer cell lines resulted in consi stent down-regulation of uPA or PAI-1 expression. In addition, anti-HER-2/n eu antibodies did not significantly affect uPA or PAI-1 expression in human cancer cell lines naturally overexpressing HER-2/neu. Conclusions: The present findings suggest that the invasive phenotype elici ted by HER-2/neu overexpression in breast cancer is not a direct effect of uPA or PAI-1 expression. HER-2/neu and the uPA/PAI-1 axis have been shown t o affect the invasive capacity of breast cancer independently. Determinatio n of uPA can provide significant additional prognostic information for MFS in HER-2/neu-positive and-negative patients.