AMPHIREGULIN, EPIDERMAL GROWTH-FACTOR RECEPTOR, AND ESTROGEN-RECEPTOREXPRESSION IN HUMAN PRIMARY BREAST-CANCER

Amphiregulin is a recently described member of the epidermal growth fa ctor family. Primary breast cancers were assessed for expression of am phiregulin by immunochemistry (111 cases), Northern, and/or dot blots (68 cases). Epidermal growth factor and estrogen receptors were measur ed in all cases. p53 and erbB-2 expression was assessed by immunohisto chemistry for most cases. There was no association of these factors wi th amphiregulin expression, which was detected by immunochemistry in 4 0 of 111 cases. A significant association of amphiregulin expression a ssessed by Northern dot blots versus immunochemical staining was seen (P 0.0016). Expression was not detected in adjacent nontumor tissue by immunochemistry. Amphiregulin was expressed in tumor epithelium, but not stromal or inflammatory cells. Expression was more common in lymph node positive cases (23 of 49; 47%) than lymph node negative cases (1 1 of 42; 26%; P = 0.04). The coexpression of epidermal growth factor r eceptor and amphiregulin in 35% of epidermal growth factor receptor po sitive cases raises the possibility of an autocrine loop in this subse t of patients. Amphiregulin stimulates fibroblast growth and is up-reg ulated in breast cancer. A possible effect on tumor stroma may relate to the association with metastases.