VASOPRESSIN GENE-RELATED PRODUCTS ARE MARKERS OF HUMAN BREAST-CANCER

Immunohistochemical analysis for products of vasopressin and oxytocin gene expression was performed on acetone-fixed tissues from 19 breast cancers representing a variety of tumor sub-types. Studies employed th e avidin-biotin complex (ABC) immunohistochemical procedure and utiliz ed rabbit polyclonal antibodies to arginine vasopressin (VP), provasop ressin (ProVP), vasopressin-associated human glycopeptide (VAG), oxyto cin (OT), oxytocin-associated human neurophysin (OT-HNP), and a mouse monoclonal antibody to vasopressin-associated human neurophysin (VP-HN P). Western Blot analysis was performed on protein extracts of fresh-f rozen tissues from 12 additional breast tumors. While VP gene related proteins were not detected in normal breast tissue, immunohistochemist ry revealed the presence of VP, ProVP, and VAG in all neoplastic cells for all of the tumor tissues examined. Vasopressin-associated human n europhysin was evident in only one of 19 acetone-fixed tumor preparati ons. However, Western blot analysis for all 12 fresh-frozen tumor samp les showed the presence of two proteins, 42,000 and 20,000 daltons, th at were immunoreactive with antibodies to VP, VP-HNP, and VAG. Oxytoci n and OT-HNP, by immunohistochemistry, were found to be common to cell s of normal breast tissues. For tumors, positive staining for OT was o bserved in 8 of 18 tumors, while OT-HNP was not detected in any of the tumors examined. These findings indicate that VP gene expression is a selective feature of all breast cancers, and that products of this ex pression might therefore be useful as markers for early detection of t his disease and as possible targets for immunotherapy.