p95HER-2 predicts worse outcome in patients with HER-2-positive breast cancer.

BACKGROUND: The HER-2 receptor undergoes a proteolytic cleavage generating an NH(2)-terminally truncated fragment, p95HER-2, that is membrane-associated and tyrosine-phosphorylated. We have reported that p95HER-2, but not the full-length receptor, p185HER-2, correlated with the extent of lymph node involvement in patients with breast cancer and its expression was significantly enhanced in nodal metastatic tissue. These facts suggested an important role for p95HER-2 either as a marker or cause of metastasis and poor outcome in breast cancer. In this work, we have studied the prognostic value of p95HER-2 in breast cancer. METHODS: Primary breast tumor tissues (n = 483) were from surgical resections conducted in hospitals in two different countries: the U.S. (n = 334) and Spain (n = 149). HER-2 protein forms, including p185HER-2 and p95HER-2, were examined in extracts of primary breast tumors by Western blot analysis. The levels of the two forms (high or low) were tested for association with other clinicopathologic factors and for correlation with disease-free survival. RESULTS: The median follow-up was 46 months. A high level of p95HER-2 in primary tumor tissue correlated with reduced 5-year disease-free survival (hazard ratio, 2.55; 95% confidence interval, 2.13-8.01; P < 0.0001). The median time for disease-free survival was 32 versus 139 months in patients with low levels of p95HER-2. In comparison, high levels of the full-length p185HER-2 did not significantly correlate with poor outcome (P > 0.1). Multivariate analysis revealed that high p95HER-2 was an independent predictor of disease-free survival (hazard ratio, 1.59; 95% confidence interval, 1.246-1.990; P = 0.0004). CONCLUSIONS: p95HER-2 expression is an independent prognostic factor in breast cancer and defines a group of patients with HER-2-positive breast cancer with significantly worse outcome.

NH(2)-terminal truncated HER-2 protein but not full-length receptor is associated with nodal metastasis in human breast cancer.

BACKGROUND: The full-length receptor p185HER-2 undergoes a metalloprotease-dependent cleavage producing a membrane-associated fragment (p95HER-2) in cultured breast cancer cells. P95HER-2 has potentially enhanced signaling activity, but its expression and role in human breast cancer is poorly characterized. PURPOSE: The purpose of this project was to characterize the expression of p95HER-2 in primary breast cancers and nodal metastasis, and to study association with clinicopathological factors. EXPERIMENTAL DESIGN: P95HER-2 and p185HER-2 were examined in 337 primary breast tumors and 81 metastatic lymph nodes by Western blot analysis, and tested for associations with other clinicopathological factors. RESULTS: P95HER-2 was present in 20.9% of primary tumors from node-negative patients, in 29.1% from patients with one to three metastatic nodes, and in 36.7% from patients with four or more metastatic nodes (P = 0.027). Whereas p185HER-2 overexpression was unrelated to nodal disease (P = 0.63), the odds of lymph node metastasis were enhanced 2.9-fold by the presence of p95HER-2 (48.8% of node-negative versus 73.5% of node-positive patients; P = 0.03; odds ratio = 2.9). P95HER-2 was more frequent in metastatic lymph nodes than in primary tumors (45.7% versus 26.7%; P = 0.0009), whereas p185HER-2 overexpression was similar in both (22.3% versus 23.5%; P = 0.933). P95HER-2 did not significantly correlate with patient age, tumor size, stage, histotype, or hormone receptor status. CONCLUSIONS: P95HER-2 in primary tumors was related to extent of lymph node involvement and was enhanced in nodal tissue suggesting an important role as a marker or cause in breast cancer metastasis. Examination of the prognostic value of p95HER-2 in breast cancer and its coexpression with metalloprotease activity seem warranted.