IMMUNOLOCALIZATION AND GENE-EXPRESSION OF OXYTOCIN RECEPTORS IN CARCINOMAS AND NONNEOPLASTIC TISSUES OF THE BREAST

Recent evidence indicates that oxytocin (OT), in addition to the induc tion of myometrial and myoepithelial cell contraction, can influence p roliferation and differentiation in developing mammary glands and irt breast cancer cells, hence the interest is detecting and locating OT r eceptors (OTRs). We produced rabbit antisera and a monoclonal antibody against a synthetic peptide corresponding to the amino terminus and a ntisera against a peptide corresponding to the carboxy terminus of the predicted OTR sequence. We tested their specificity, in immunoblots a nd immunocytochemical tests. All of the antibodies specifically staine d myometrium (at term of pregnancy). In the human breast, OTRs were de tected in myoepithelial cells along ducts of normal lobules and in scl erosing adenosis. Intraductal cells itt benign hyperplastic lesions we re also positive. OTRs were demonstrated in cases of primary and metas tatic carcinomas of the breast. In the same tissues, OTR gene expressi on was shown by reverse transcriptase polymerase chain reaction proced ures detecting the specific mRNA. These results suggest that the inter action be tween OT and its receptors might play a role in the origin a nd evolution of non-neoplastic lesions and carcinomas of the breast.