PIP GCDFP-15 GENE-EXPRESSION AND APOCRINE DIFFERENTIATION IN CARCINOMAS OF THE BREAST/

The frequency and the significance of apocrine differentiation in carc inomas of the breast are uncertain, because of the lack of reliable an d reproducible criteria for morphological diagnosis. The 15 kDa glycop rotein of cystic breast disease (GCDFP-15) is regarded as a specific f unctional marker of apocrine cells. Expression of the prolactin-induci ble protein (PIP)/GCDFP-15 gene was investigated by Northern blot anal ysis and in situ hybridization in breast cancer cell lines and in an u nselected series (33 cases) of primary carcinomas of the breast. On th e same cases, histological assessment of apocrine differentiation and immunocytochemical detection of GCDFP-15 were also performed and corre lated with follow-up data. The presence of PIP/GCDFP-15 mRNA was a fea ture of a relatively high number of cases, but was incompletely correl ated with histological and immunocytochemical evidences of apocrine di fferentiation. Expression of the PIP/GCDFP-15 gene was significantly a ssociated with relapse-free survival, and may represent a novel variab le of functional and prognostic relevance.