Mechanisms of synergism between antagonists of growth hormone‐releasing hormone and antagonists of luteinizing hormone‐releasing hormone in shrinking experimental benign prostatic hyperplasia

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The etiology of benign prostatic hyperplasia (BPH) is multifactorial, and chronic inflammation plays a pivotal role in its pathogenesis. Growth hormone-releasing hormone (GHRH) is a hypothalamic neuropeptide that has been shown to act as paracrine/autocrine factor in various malignancies including prostate cancer. GHRH and its receptors are expressed in experimental models of BPH, in which antagonists of GHRH suppressed the levels of proinflammatory cytokines and altered the expression of genes related to epithelial-to-mesenchymal transition (EMT). We investigated the effects of GHRH antagonist on prostatic enlargement induced by inflammation. Autoimmune prostatitis in Balb/C mice was induced by a homogenate of reproductive tissues of male rats. During the 8-wk induction of chronic prostatitis, we detected a progressive increase in prostatic volume reaching 92% at week 8 compared with control (P < 0.001). Daily treatment for 1 mo with GHRH antagonist MIA-690 caused a 30% reduction in prostate volume (P < 0.05). Conditioned medium derived from macrophages increased the average volume of spheres by 82.7% (P < 0.001) and elevated the expression of mRNA for N-cadherin, Snail, and GHRH. GHRH antagonist reduced the average volume of spheres stimulated by inflammation by 75.5% (P < 0.05), and TGF-β2 by 91.8% (P < 0.01). The proliferation of primary epithelial cells stimulated by IL-17A or TGF-β2 was also inhibited by 124.1% and 69.9%, respectively. GHRH stimulated the growth of BPH-1 and primary prostate spheres. This study provides evidence that GHRH plays important roles in prostatic inflammation and EMT and suggests the merit of further investigation to elucidate the effects of GHRH antagonists in prostatitis and BPH. chronic prostatic inflammation | neuropeptide | prostatic hyperplasia | targeted therapy | experimental autoimmune prostatitis

Section: Significancementioning

confidence: 69%

Antagonists of growth hormone-releasing hormone inhibit proliferation induced by inflammation in prostatic epithelial cells

Popovics

Salgueiro

Kovacs

et al. 2017

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“…Hypothalamic neurohormone GHRH and GHRH-R are not confined to the hypothalamic-pituitary axis, however, but are also produced by various extrahypothalamic sites. GHRH/GHRH-R modulates cell proliferation and apoptosis in many tissues, including prostate (8)(9)(10)(11)(12).…”

mentioning

confidence: 99%

Preclinical efficacy of growth hormone-releasing hormone antagonists for androgen-dependent and castration-resistant human prostate cancer

Fahrenholtz

Rick

García

et al. 2014

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Advanced hormone-sensitive prostate cancer responds to androgen-deprivation therapy (ADT); however, therapeutic options for recurrent castration-resistant disease are limited. Because growth hormone-releasing hormone (GHRH) and GHRH receptor (GHRH-R) are regulated in an autocrine fashion in prostate cancer, inhibition of GHRH-R represents a compelling approach to treatment. We investigated the effects of the latest series of improved, highly potent GHRH antagonists-MIA-602, MIA-606, and MIA-690-on the growth of androgen-dependent as well as castration-resistant prostate cancer (CRPC) cells in vitro and in vivo. GHRH-R and its splice variant, SV1, were present in 22Rv1, LNCaP, and VCaP human prostate cancer cell lines. Androgen-dependent LNCaP and VCaP cells expressed higher levels of GHRH-R protein compared with castration-resistant 22Rv1 cells; however, 22Rv1 expressed higher levels of SV1. In vitro, MIA-602 decreased cell proliferation of 22Rv1, LNCaP, and VCaP prostate cancer cell lines by 70%, 61%, and 20%, respectively (all P < 0.05), indicating direct effects of MIA-602. In vivo, MIA-602 was more effective than MIA-606 and MIA-690 and decreased 22Rv1 xenograft tumor volumes in mice by 63% after 3 wk (P < 0.05). No noticeable untoward effects or changes in body weight occurred. In vitro, the VCaP cell line was minimally inhibited by MIA-602, but in vivo, this line showed a substantial reduction in growth of xenografts in response to MIA-602, indicating both direct and systemic inhibitory effects. MIA-602 also further inhibited VCaP xenografts when combined with ADT. This study demonstrates the preclinical efficacy of the GHRH antagonist MIA-602 for treatment of both androgen-dependent and CRPC.androgen-independent | G protein-coupled receptor | hypothalamic neurohormone | neuropeptide | targeted therapy

“…We also showed that neurohormones including growth hormone-releasing hormone (GHRH) and luteinizing hormone-releasing hormone (LHRH) can act as growth factors in experimental BPH. Potent synthetic antagonists of GHRH and of LHRH cause marked shrinkage of experimental BPH by direct inhibition of prostatic GHRH and LHRH and by suppression of proinflammatory IL-1β, NF-κβ/p65, and COX-2 and various other growth factors and inflammatory cytokines (27)(28)(29)(30).…”

mentioning

confidence: 99%

Shrinkage of experimental benign prostatic hyperplasia and reduction of prostatic cell volume by a gastrin-releasing peptide antagonist

Rick

Abi-Chaker

Szalontay

et al. 2013

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Gastrin releasing-peptide (GRP) is a potent growth factor in many malignancies. Benign prostatic hyperplasia (BPH) is a progressive age-related proliferation of glandular and stromal tissues; various growth factors and inflammatory processes are involved in its pathogenesis. We have demonstrated that potent antagonists of GRP inhibit growth of experimental human tumors including prostate cancer, but their effect on models of BPH has not been studied. Here, we evaluated the effects of GRP antagonist RC-3940-II on viability and cell volume of BPH-1 human prostate epithelial cells and WPMY-1 prostate stromal cells in vitro, and in testosterone-induced BPH in Wistar rats in vivo. RC-3940-II inhibited the proliferation of BPH-1 and WPMY-1 cells in a dosedependent manner and reduced prostatic cell volume in vitro. Shrinkage of prostates was observed after 6 wk of treatment with RC-3940-II: a 15.9% decline with 25 μg/d; and a 18.4% reduction with 50 μg/d (P < 0.05 for all). Significant reduction in levels of proliferating cell nuclear antigen, NF-κβ/p50, cyclooxygenase-2, and androgen receptor was also seen. Analysis of transcript levels of genes related to growth, inflammatory processes, and signal transduction showed significant changes in the expression of more than 90 genes (P < 0.05). In conclusion, GRP antagonists reduce volume of human prostatic cells and lower prostate weight in experimental BPH through direct inhibitory effects on prostatic GRP receptors. GRP antagonists should be considered for further development as therapy for BPH.bombesin | cell volume measurement | prostatic inflammation | rodent benign prostatic hyperplasia model | targeted therapy H ormonal polypeptides, bombesin (BN) and gastrin-releasing peptide (GRP), can act as autocrine and paracrine growth factors, and regulate cellular growth, differentiation, and apoptosis (1, 2). Tetradecapeptide bombesin was isolated from the skin of the European fire-bellied toad (Bombina bombina) (3), and subsequently, two mammalian bombesin-like peptides were characterized: GRP and neuromedin B (NMB) (4). GRP and BN influence the secretion of gastrointestinal hormones, stimulate the release of gastrin and somatostatin, induce pancreatic exocrine secretion (5), and induce contractions of the smooth muscle of the stomach, gall bladder, uterus, urinary bladder, and prostate (6). GRP was first shown to be a mitogen for Swiss 3T3 murine embryonal fibroblasts and, subsequently, for a number of normal cell types and cancers in vivo and in cell culture (7). GRP is now recognized as the prototypical autocrine growth factor, based on the detection of GRP and its receptors in small cell lung carcinoma and other tumors (8). GRP was shown to stimulate growth of several other types of carcinomas including those of prostate, breast, colon, and pancreas (9). Three different receptor subtypes for the BN/GRP family of peptides have been described in mammals (10). Receptor subtype 1 (termed GRP-R or BB 2 ) binds BN, GRP, and GRP antagonist RC-3940-II with high affinity (11). ...