Growth hormone receptor is expressed in human breast cancer

Several clinical observations and experimental studies indicate that pituit ary hormones, including growth hormone, play a role in the development of h uman breast cancer, We analyzed 48 human breast carcinomas using reverse tr anscription polymerase chain reaction, irnmunohistochemistry, and Western b lotting techniques to assess growth hormone receptor expression. In 17 of t hese cases, adjacent normal breast tissue was similarly analyzed. These ana lyses revealed that growth hormone receptor (GHR) is expressed in human bre ast cancer and appeals to be up-regulated compared to adjacent normal breas t tissue. GHR expression correlated inversely with tumor grade and MIB-1 in dex. Progesterone receptor expression correlated positively with GHR expres sion. These findings, along with our observation of GHR expression in breas t cancer stromal cells and previous reports of local production of growth h ormone in breast carcinoma, suggest that GHR-mediated signaling pathways ar e involved in the development of human breast cancer, possibly via autocrin e or paracrine mechanisms.