The effect of a novel antagonist of growth hormone releasing hormone on cell proliferation and on the key cell signaling pathways in nine different breast cancer cell lines.

Abstract

Growth hormone releasing hormone (GHRH) antagonists have been developed for the treatment of various cancers. We investigated the effects of a novel GHRH antagonist, MIA-602, on nine breast cancer cell lines, differing in their expression for estrogen-, progesterone- and HER-2 receptors. We detected the presence of pituitary-type GHRH receptors (pGHRH-R) on 6 of the 9 breast cancer cell lines. The main splice variant of pGHRH-R, SV1, was found on all 9 cell lines. MTT assay showed that following treatment with MIA-602, cell viability decreased significantly in all 9 cell lines. The reduction in cell viability was greater in cells positive for both pGHRH-R and SV1, than in cells positive for only SV1, but the difference was not significant. Using Western blotting, we demonstrated that the levels of phospho-Akt, -GSK3β and -ERK1/2 decreased significantly following exposure to MIA-602 and the level of phospho-p38 increased after treatment. The reduction of the phosphorylated anti-apoptotic proteins was significantly greater in cells where both pGHRH-R and SV1 were present, than where only SV1 was expressed. In conclusion, our study shows that MIA-602 is effective against a wide range of breast cancer cells in vitro, independently of their receptor positivity, suggesting the potential use of GHRH antagonists also in the treatment of triple-negative breast cancer. The effect of MIA-602 was mediated nearly as well in tumors that expressed only the SV1 receptor compared to those in which both SV1 and pGHRH-R were present, although a difference could be detected at the level of cell signaling.

• Authors: Eva Pozsgai, Andrew V Schally, Eniko Hocsak, Marta Zarandi, Ferenc Rick, Szabolcs Bellyei
• Journal: International journal of oncology (Int J Oncol) Vol. 39 Issue 4 Pg. 1025-32 (Oct 2011) ISSN: 1791-2423 [Electronic] Greece
• PMID: 21701777 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• GHRH(1-29)NH2, (PhAc-Ada)(0)-Tyr(1), Arg(2), Fpa(5,6), Ala(8), Har(9), Tyr(Me)(10), His(11), Orn(12,) Abu(15), His(20), Orn(21), Nle(27), Arg(28), Har(29)-
• Receptors, Estrogen
• Receptors, Neuropeptide
• Receptors, Pituitary Hormone-Regulating Hormone
• Receptors, Progesterone
• Sermorelin
• Growth Hormone-Releasing Hormone
• ERBB2 protein, human
• Receptor, ErbB-2
• GSK3B protein, human
• Glycogen Synthase Kinase 3 beta
• Oncogene Protein v-akt
• MAPK1 protein, human
• Mitogen-Activated Protein Kinase 1
• Mitogen-Activated Protein Kinase 3
• p38 Mitogen-Activated Protein Kinases
• Glycogen Synthase Kinase 3
• somatotropin releasing hormone receptor

Topics

• Apoptosis (drug effects)
• Breast Neoplasms (drug therapy, metabolism, pathology)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• Cell Survival (drug effects)
• Female
• Glycogen Synthase Kinase 3 (metabolism)
• Glycogen Synthase Kinase 3 beta
• Growth Hormone-Releasing Hormone (antagonists & inhibitors)
• Humans
• Mitogen-Activated Protein Kinase 1 (metabolism)
• Mitogen-Activated Protein Kinase 3 (metabolism)
• Oncogene Protein v-akt (metabolism)
• Phosphorylation (drug effects)
• Receptor, ErbB-2 (biosynthesis)
• Receptors, Estrogen (biosynthesis)
• Receptors, Neuropeptide (metabolism)
• Receptors, Pituitary Hormone-Regulating Hormone (metabolism)
• Receptors, Progesterone (biosynthesis)
• Sermorelin (analogs & derivatives, pharmacology)
• Signal Transduction (drug effects)
• p38 Mitogen-Activated Protein Kinases (metabolism)