sermorelin and Breast-Neoplasms

This study evaluated the effects of a modern antagonistic analog of GHRH on tumor growth and on expression of inflammatory cytokine genes in two models of human triple negative breast cancers (TNBC). The TNBC subtype is refractory to the treatment options available for other hormone-independent breast cancers. Inflammatory cytokines play a major role in the cellular signaling associated with breast cancer pathogenesis and enhance epithelial-mesenchymal transitions (EMT), drug resistance, and metastatic potential. Growth hormone-releasing hormone (GHRH) is a hypothalamic neuropeptide which regulates the synthesis and release of growth hormone by the pituitary and is an autocrine/paracrine growth factor for multiple human cancers. The effects of analogs of GHRH on tumoral cytokine expression have not been previously investigated. Animals bearing xenografts of the human TNBC cell lines, HCC1806 and MX-1, were treated with MIA-602, an antagonistic analog of GHRH. Treatment with MIA-602 significantly reduced tumor growth. We quantified transcript levels of the genes for several inflammatory cytokines. Expression of INFγ, IL-1α, IL-4, IL-6, IL-8, IL-10, and TNFα, was significantly reduced by treatment with MIA-602. We conclude that treatment of TNBC with GHRH antagonists reduces tumor growth through an action mediated by tumoral GHRH receptors and produces a suppression of inflammatory cytokine signaling. Silencing of GHRH receptors in vitro with siRNA inhibited the expression of GHRH-R genes and inflammatory cytokine genes in HCC1806 and MX-1 cells. Further studies on GHRH antagonists may facilitate the development of new strategies for the treatment of resistant cancers.

Topics: Animals; Breast Neoplasms; Cell Line, Tumor; Cytokines; Female; Gene Expression; Gene Silencing; Growth Hormone-Releasing Hormone; Humans; Mice; Mice, Nude; Receptor, ErbB-2; Receptors, Estrogen; Receptors, Neuropeptide; Receptors, Pituitary Hormone-Regulating Hormone; Receptors, Progesterone; RNA, Messenger; RNA, Small Interfering; Sermorelin; Signal Transduction; Xenograft Model Antitumor Assays

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.

Topics: Apoptosis; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Cell Survival; Female; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Growth Hormone-Releasing Hormone; Humans; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Oncogene Protein v-akt; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Receptor, ErbB-2; Receptors, Estrogen; Receptors, Neuropeptide; Receptors, Pituitary Hormone-Regulating Hormone; Receptors, Progesterone; Sermorelin; Signal Transduction

Triple-negative breast cancers do not express receptors for estrogen or progesterone and do not overexpress HER2. These tumors have an unfavorable prognosis and at present chemotherapy is the only treatment option. Because the antagonists of growth hormone-releasing hormone (GHRH) have been shown to inhibit growth of a variety of cancers by endocrine and paracrine/autocrine mechanisms, we evaluated the expression of GHRH receptors in human specimens of triple-negative breast cancers and the response to GHRH by in vitro models. In samples of triple-negative breast cancers we found mRNA expression for the GHRH receptor and its functional splice variant SV1 in 25 and 70% of the cases, respectively and for GHRH in 80% of the samples. Immunoreaction of SV1 was detected in the human triple-negative breast cancer cell line HCC1806 while HCC1937 was negative. The growth of HCC1806 was stimulated by GHRH(1-44)NH(2) and inhibited by GHRH antagonist MZ-J-7-118. In addition, in HCC1806 MAP-kinases ERK-1/2 were activated by GHRH. Our findings suggest the existence of an autocrine loop consisting of GHRH and GHRH receptors in triple-negative breast cancers. Our in vitro studies demonstrate that targeting the GHRH receptor may be a therapeutic option which should be evaluated in studies in vivo.

Topics: Blotting, Western; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Extracellular Signal-Regulated MAP Kinases; Female; Humans; Receptors, Neuropeptide; Receptors, Pituitary Hormone-Regulating Hormone; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sermorelin

GHRH antagonists have been shown to inhibit growth of various human cancer cell lines xenografted into nude mice including estrogen receptor negative human breast cancers. Previous observations also suggest that GHRH locally produced in diverse neoplasms including breast cancer might directly affect proliferation of tumor cells. In the present study we demonstrate that a novel highly potent GHRH antagonist JMR-132 strongly inhibits the proliferation of both estrogen receptor negative SKBR 3 and estrogen receptor positive ZR 75 human breast cancer cell lines in vitro. The proliferation in vitro of ZR 75 and SKBR 3 was increased after direct stimulation with GHRH(1-29)NH2. The GHRH antagonist JMR-132 had a significant antiproliferative activity in the absence of GHRH and nullified the proliferative effect of GHRH in these cell lines. SKBR 3 and ZR 75 expressed the GHRH ligand as well as the pituitary type of GHRH-receptor, which likely appears to mediate the antiproliferative mechanisms in these cell lines. These in vitro results suggest that JMR-132 is a potent inhibitor of breast cancer growth, independent of the estrogen receptor status. Further investigations on the combination treatment with endocrine agents affecting the estrogen pathway and GRHR antagonists are needed in order to improve the treatment of breast cancer.

Topics: Antineoplastic Agents; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Cell Survival; Female; Growth Hormone-Releasing Hormone; Humans; Receptors, Estrogen; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sermorelin

GHRH, in addition to stimulating the release of growth hormone (GH) from the pituitary, is a trophic factor for pituitary somatotrophs. Growth hormone-releasing hormone is also expressed in the gonads, gastrointestinal tract, pancreas, thymus, and lymphocytes, as well as in tumors of the pancreas, lung, central nervous system, and breast. Since GHRH has mitogenic effects, we examined the hypothesis that GHRH is an autocrine/paracrine growth factor in neoplastic breast tissue. The effect of disrupting endogenous GHRH on cell growth and apoptosis of MDA231 cells was examined through the use of a competitive GHRH antagonist, [N-acetyl-Tyr1, D-Arg2] fragment 1-29Amide (GHRHa). Cell proliferation was determined by direct cell counting and tritiated thymidine incorporation. Apoptosis was analyzed by examination of DNA laddering and nuclear condensation. GHRHa resulted in a dose-dependent, transient, and reversible decrease in cell number, proliferation rate, and tritiated thymidine uptake. Conversely, GHRHa led to a marked and dose-dependent increase in both DNA laddering and nuclear condensation. These results indicate that disruption of endogenous GHRH action in MDA231 cells results in both decreased cellular proliferation and increased apoptosis. Taken together, the findings suggest that endogenous GHRH acts as an autocrine/paracrine factor in the regulation of growth of at least some breast cancer cell types.

Topics: Apoptosis; Breast Neoplasms; Cell Division; Cell Nucleus; DNA Fragmentation; Growth Hormone-Releasing Hormone; Humans; Peptide Fragments; Sermorelin; Tumor Cells, Cultured

Since antagonists of growth hormone-releasing hormone (GH-RH) inhibit proliferation of various tumors, in this study we investigated the effects of GH-RH antagonists MZ-5-156 or JV-1-36 on growth of estrogen-independent MDA-MB-468 human breast cancers xenografted into nude mice. Both GH-RH antagonists administered at a dose of 20 microg/day induced regression of some and growth-arrest of other tumors, while control tumors continued to grow. After 5 weeks of therapy with MZ-5-156 or JV-1-36, final volume and weight of MDA-MB-468 tumors were significantly decreased (all p values < 0.001) and serum IGF-I levels as well as tumor IGF-I mRNA expression were reduced as compared with controls. High affinity binding sites for IGF-I were detected by the ligand binding method. Gene expression of human IGF-I receptors, as measured by the RT-PCR, was not significantly different in control and treated MDA-MB-468 tumors. In cell culture, IGF-I did not stimulate, GH-RH slightly stimulated, while MZ-5-156 and JV-1-36 inhibited proliferation of MDA-MB-468 cells known to possess defective insulin and IGF-I receptor signaling. The expression of mRNA for human GH-RH was found in five of 8 tumors treated with GH-RH antagonists, and in one of the five control tumors. These results suggest that GH-RH antagonists inhibit MDA-MB-468 breast cancers possibly through mechanisms involving interference with locally produced GH-RH.

Topics: Animals; Breast Neoplasms; Disease Models, Animal; DNA Primers; Female; Gene Expression Regulation, Neoplastic; Growth Hormone-Releasing Hormone; Humans; Insulin-Like Growth Factor I; Insulin-Like Growth Factor II; Mice; Mice, Nude; Radioimmunoassay; Receptor, IGF Type 1; Receptors, Neuropeptide; Receptors, Pituitary Hormone-Regulating Hormone; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sermorelin; Transplantation, Heterologous; Tumor Cells, Cultured

Antagonistic analogs of growth hormone-releasing hormone (GHRH) inhibit growth of various human cancers both in vivo and in vitro. GHRH, vasoactive intestinal peptide (VIP), and pituitary adenylate cyclase-activating peptide stimulate cyclic AMP (cAMP) release from various human cancer cell lines in vitro. Thus, in the present study, we investigated the effects of antagonistic analogs of GHRH on the GHRH- and VIP-induced cAMP release from cultured human cancer cells in a superfusion system. Various human cancer cell lines were exposed to human GHRH(1-29)NH2 (2-20 nM) or VIP (0.1-5 nM) repeatedly for 12 min or continuously for 96 min. GHRH antagonist MZ-5-156 at 100 to 200 nM concentration inhibited the GHRH- or VIP-induced cAMP release from mammary (MDA-MB-468), prostatic (PC-3), and pancreatic (SW-1990 and CAPAN-2) cancer cells. These results show that antagonistic analogs of GHRH suppress the stimulatory effects of GHRH and VIP on the cAMP production of various cancer cells. Because cAMP is a potent second messenger controlling many intracellular functions, including the stimulation of cell growth, an inhibition of autocrine/paracrine action of GHRH by the GHRH antagonists may provide the basis for the development of new methods for cancer treatment.

Topics: Animals; Breast Neoplasms; Cell Division; Cyclic AMP; Female; Growth Hormone-Releasing Hormone; Human Growth Hormone; Humans; In Vitro Techniques; Male; Neoplasms; Pancreatic Neoplasms; Pituitary Gland, Anterior; Prostatic Neoplasms; Rats; Second Messenger Systems; Sermorelin; Tumor Cells, Cultured; Vasoactive Intestinal Peptide