MAMMAGLOBIN, A MAMMARY-SPECIFIC MEMBER OF THE UTEROGLOBIN GENE FAMILY, IS OVEREXPRESSED IN HUMAN BREAST-CANCER

In this report, we describe a novel cDNA isolated from a primary human breast adenocarcinoma and differentially expressed in several breast carcinoma cell lines. The protein encoded by this cDNA, which we have named mammaglobin, is homologous to a family of secreted proteins that includes rat prostatic steroid-binding protein subunit C3, human Clar a cell 10-kilodalton protein, and rabbit uteroglobin. Expression of th e mammaglobin gene is restricted to the adult mammary gland. More sign ificantly, in an analysis of 35 breast tumor biopsies, mammaglobin mRN A levels were increased at least 10-fold relative to normal breast tis sue in 232 of cases. The breast-specific expression of this potentiall y secreted protein and its frequent overexpression in primary human br east tumors suggest that mammaglobin may be a novel marker for the man agement of breast cancer.