Growth hormone (GH) is vital for normal human cells. The secretion of GH is controlled by growth hormone-releasing hormone (GHRH). But when normal cellular checks and balances fail, GH and GHRH can stimulate cancer growth.

New research from the University of Miami Sylvester Comprehensive Cancer Center identifies a protein receptor that is activated by GHRH. It plays a key role in the growth of certain malignancies, including prostate, pancreatic, kidney, breast, ovarian, and bone cancer.

Nobel laureate Andrew V. Schally, Ph.D., M.D.hc., professor in the Department of Pathology and the Division of Hematology/Oncology at the Miller School of Medicine, has long been a leader in the study of hormone-related cancers. He and his colleague, Nektarios Barabutis, Ph.D., showed that a splice variant (SV1) of GHRH receptor stimulated breast cancer cells. The research was published in March in the Proceedings of the National Academy of Sciences USA.

SV1 is a variant of hormone growth factor receptor—a protein molecule that “receives” and responds to GHRH. In a normal setting, GHRH binds to its receptors in the pituitary gland and stimulates the release of growth hormone. How GHRH attached to and stimulated cancer cells wasn’t known.

Schally and his colleagues were able to show that cells transfected with the SV1 variant were five times more likely to stimulate tumor cell growth than control cells. Identifying the importance of this splice variant in cancer growth is critical for developing specific GHRH antagonists for cancer treatment—the focus of Schally’s career.