Expression of NKX3.1 in normal and malignant tissues

BACKGROUND. NKX3.1, a member of the NK-class of homeodomain proteins, is expressed primarily in the adult prostate and has growth suppression and differentiating effects in prostate epithelial cells. METHODS. We performed immumohistochemical analysis for NKX3.1 and PSA expression in 4,061 samples included in a tissue microarray of a broad spectrum of human cancers and normal tissues. RESULTS. NKX3.1 expression was seen in prostate epithelial cells, prostate cancer, normal testis, 9% of primary and 5% of metastatic infiltrating ductal breast carcinoma, and 27% of primary and 26% of metastatic infiltrating lobular breast carcinoma. In a cohort of 474 primary breast cancers with median follow-up over 62.5 month survival, we found no effect of NKX3.1 expression on prognosis. NKX3.1 expression was more restricted than the spectrum of prostate specific antigen expression. CONCLUSIONS. Expression of NKX3.1 is highly restricted and is found primarily in benign and malignant prostatic epithelial cells and also in normal testis and lobular carcinoma of the breast. (C) 2003 Wiley-Liss, Inc.