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Query: UMLS:C0376358 (prostate cancer)
 59,338 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We present a review of the epidemiological evidence for relations of prostate cancer risk to circulating total and bioavailable androgens, to alterations in the metabolism of insulin-like growth factor-1 (IGF-1), and to anthropometric indices of longitudinal growth (body stature) and overweight. In addition, we review the physiological inter-relationships between insulin, growth hormone/IGF-1 axis, and sex steroid metabolism, as well as the associations of bioavailable sex steroid levels with overweight and obesity. A first conclusion of this review is that, taken together, epidemiological studies have provided little support for the hypothesis that prostate cancer risk is increased in men with elevated total or biovailable testosterone (T). Although one prospective study showed an increased risk in men with low plasma sex hormone-binding globulin (SHBG) and with elevated plasma T for given levels of SHBG, this was not confirmed by results from other cohort studies. A second conclusion is that overweight, which is generally associated with moderate reductions in both total and bioavailable plasma T, appears to be unrelated to any significant increase or decrease in prostate cancer risk. However, significant increases in risk have been observed for men with a taller body stature, or with elevated plasma IGF-1. IGF-1 may directly enhance prostate tumorigenesis by inhibiting apoptosis and by stimulating cell proliferation. In addition, IGF-1 downregulates the synthesis of SHBG, and enhances sex steroid synthesis. Therefore, we do not entirely rule out that due to an elevation of plasma IGF-1 levels, men at increased risk of prostate cancer also have mildly elevated plasma bioavailable T, which epidemiological studies may have failed to demonstrate because of methodological problems. Prostate Cancer and Prostatic Diseases (2000) 3, 157-172
Prostate Cancer Prostatic Dis 2000 Nov
PMID:Plasma androgens, IGF-1, body size, and prostate cancer risk: a synthetic review. 1249 92

The antiproliferative effects of an antagonist of growth hormone-releasing hormone (GHRH) JV-1-38 were evaluated in nude mice bearing s.c. xenografts of LNCaP and MDA-PCa-2b human androgen-sensitive and DU-145 androgen-independent prostate cancers. In the androgen-sensitive models, JV-1-38 greatly potentiated the antitumor effect of androgen deprivation induced by surgical castration, but was ineffective when given alone. Thus, in castrated animals bearing MDA-PCa-2b cancers, the administration of JV-1-38 for 35 days virtually arrested tumor growth (94% inhibition vs. intact control, P < 0.01; and 75% vs. castrated control, P < 0.05). The growth of LNCaP tumors was also powerfully suppressed by JV-1-38 combined with castration (83% inhibition vs. intact control, P < 0.01; and 68% vs. castrated control, P < 0.05). However, in androgen-independent DU-145 cancers, JV-1-38 alone could inhibit tumor growth by 57% (P < 0.05) after 45 days. In animals bearing MDA-PCa-2b and LNCaP tumors, the reduction in serum prostate-specific antigen levels, after therapy with JV-1-38, paralleled the decrease in tumor volume. Inhibition of MDA-PCa-2b and DU-145 cancers was associated with the reduction in the expression of mRNA and protein levels of vascular endothelial growth factor. The mRNA expression for GHRH receptor splice variants was found in all these models of prostate cancer. Our results demonstrate that GHRH antagonists inhibit androgen-independent prostate cancers and, after combination with androgen deprivation, also androgen-sensitive tumors. Thus, the therapy with GHRH antagonist could be considered for the management of both androgen-dependent or -independent prostate cancers.
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PMID:Growth hormone-releasing hormone (GHRH) antagonists inhibit the proliferation of androgen-dependent and -independent prostate cancers. 1253 52

The incidence of colon, pancreatic, and kidney cancers, as well as aggressive prostate cancer in men, and breast and endometrial cancer in women is invariably high in Western countries. Nutritional and related factors have been typically implicated. This review presents a model integrating nutrition, insulin and IGF-1 physiology ("bioactive" IGF-1), and carcinogenesis based on the following: (1) insulin and the IGF-1 axis function in an integrated fashion to promote cell growth and survival; (2) chronic exposure to these growth properties enhances carcinogenesis; (3) factors that influence bioactive IGF-1 will affect cancer risk. The model presented here summarizes the data that chronic exposure to high levels of insulin and IGF-1 may mediate many of the risk factors for some cancers that are high in Western populations. This hypothesis may help explain some of the epidemiologic patterns observed for these cancers, both from a cross-national perspective and within populations. Of particular importance is that some of relevant factors are modifiable through nutritional and lifestyle interventions. Out of a variety of perspectives presented, nutritional manipulation through the insulin pathway may be more feasible than attempting to influence total IGF-1 concentrations, which are determined largely by growth hormone. Further study is required to test these conclusions.
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PMID:Nutrition, insulin, insulin-like growth factors and cancer. 1471 Mar 48

Various hormones and growth factors have been implicated in progression of prostate cancer, but their role and the underlying molecular mechanism(s) involved remain poorly understood. In this study, we investigated the role of human growth hormone (GH) and its receptor (GHR) in human prostate cancer. We first demonstrated mRNA expression of GHR and of its exon 9-truncated isoform (GHR(tr)) in benign prostate hyperplasia (BPH) and prostate adenocarcinoma patient tissues, as well as in LNCaP, PC3 and DU145 human prostate cancer cell lines. GHR mRNA levels were 80% higher and GHR(tr) only 25% higher, in the carcinoma tissues than in BPH. Both isoforms were also expressed in LNCaP and PC3 cell lines and somewhat less so in DU145 cells. The LNCaP cell GHR protein was further characterized, on the basis of its M(r) of 120kDa, its binding to two different GHR monoclonal antibodies, its high affinity and purely somatogenic binding to (125)I-hGH and its ability to secrete GH binding protein, all characteristic of a functional GHR. Furthermore, GH induced rapid, time- and dose-dependent signaling events in LNCaP cells, including phosphorylation of JAK2 tyrosine kinase, of GHR itself and of STAT5A (JAK2-STAT5A pathway), of p42/p44 MAPK and of Akt/PKB. No effect of GH (72h) could be shown on basal or androgen-induced LNCaP cell proliferation nor on PSA secretion. Interestingly, however, GH caused a rapid (2-12h) though transient striking increase in immunoreactive androgen receptor (AR) levels (< or =5-fold), followed by a slower (24-48h) reduction (< or = 80%), with only modest parallel changes in serine-phosphorylated AR. In conclusion, the GH-induced activation of signaling pathways, its effects on AR protein in LNCaP cells and the isoform-specific regulation of GHR in prostate cancer patient tissues, suggest that GH, most likely in concert with other hormones and growth factors, may play an important role in progression of human prostate cancer.
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PMID:Growth hormone (GH) receptors in prostate cancer: gene expression in human tissues and cell lines and characterization, GH signaling and androgen receptor regulation in LNCaP cells. 1519 5

The aim of the study was to quantify the expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) in prostate cancer and adjacent non-tumorous tissue in a standardized experimental set-up and to evaluate the paracrine effects of three endothelial stimuli on neovascularisation. Immunohistochemical staining of prostate cancer (PCa) specimens for VEGF, bFGF, EGF and the endothelial marker CD31 was performed (n=56). Sections were analyzed for growth factor-positive cancer/epithelial cells as well as staining intensity in (I) malignant and (II) non-tumorous tissue. Within PCa the topographic relationship (TR) of maximum microvessel density (MWD) and maximum expression of each growth factor was assessed. The number of VEGF- and EGF-positive cells in PCa was significantly enhanced compared with non-tumorous tissue (p<0.0001), whereas there was no difference in staining intensity. In contrast, the staining intensity of bFGF sections revealed a stronger expression in non-tumorous tissue compared with PCa (p<0.0001). In benign glands, VEGF, EGF and bFGF expression is chiefly restricted to basal cells. VEGF and EGF displayed a close TR in 65 and 57% of cases, respectively, whereas bFGF revealed a close TR in only 43% of PCa specimens. The results outline the relationship of the investigated growth factors and angiogenesis in PCa, which is strongest for VEGF and EGF. The relevance of VEGF and EGF is underlined by the increased number of positive cancer cells. Although previously reported to be a pro-angiogenic growth hormone, bFGF appears to play an assimilably minor role in the angiogenesis of PCa.
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PMID:Expression of pro-angiogenic growth factors VEGF, EGF and bFGF and their topographical relation to neovascularisation in prostate cancer. 1525 Jan 2

The endocrine system of aging males reveals changes of more or less unknown significance for estrogens, dehydroepiandrosterone (DHEA), melatonin and growth hormone. The difference between physiological changes and clear hormone deficiency is not really understood and the clinical relevance of the observed changes needs to be investigated. Estrogens do not show any changes, but DHEA, melatonin or growth hormone show several changes in their concentrations concomitant with increasing age, without validated clinical significance. According to the guidelines of the ISSAM, the significance of changes in DHEA, DHEAS, melatonin, growth hormone and IGF-1 are not well enough understood to justify routine examination when investigating late-onset hypogonadism in aging men. There is no indication for treatment with these hormones (with the exception of, e.g., estrogens in prostate cancer or male-to-female-transsexualism), as the assumed positive effects as well as negative side effects are not clearly understood and need further investigation.
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PMID:[Hormone therapy in the aging male. Estrogen, DHEA, melatonin, somatotropin]. 1530 6

Is well being in the elderly be improved by hormone replacement therapy which compensate deficits accounting for generalized weakness, poor endurance, loss of muscle strength, impaired mobility and balance and decreased cognitive functions? Hormone replacement therapy of menopause has favorable effects on bone loss and decreased cognitive functions but also on several unpleasant symptoms--vasomotor instability, skin atrophy, mucosal dryness, anxiety and fatigue--but at the prize of increased incidence of cancer and cardiovascular morbidity. Decreased testosterone levels in elderly men are associated with increased fatigability, decreased muscle strength and bone mass and increased risks of accelerated atheromatosis. Testosterone substitution seems to be helpful but with side effects, particularly development of prostate cancer. Aging also affects adrenal function. The consequences of decreased DHEA production are still matter of debate. DHEA administration in elderly women seems to be associated with favorable effects on physical and psychological well being. Somatopause is characterized by a progressive decrease of growth hormone production starting as soon as the third decade. Growth hormone therapy has favorable effects on lean body mass, skin atrophy as well on body fat reduction. However, numerous side effects and the theoretical increased risk of cancer limit the use of growth hormone therapy in the elderly.
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PMID:[Hormone therapy of ageing: myths and realities]. 1551 74

Antagonists of growth hormone-releasing hormone (GHRH) exert antiproliferative effects directly on cancer cells, which are mediated by the tumoral GHRH receptors. However, the signal transduction pathways involved in antiproliferative effect of GHRH antagonists have not yet been elucidated. We used flow cytometry to investigate whether GHRH antagonist JV-1-38 can induce changes in the cytosolic free Ca2+ concentration leading to apoptosis in LNCaP human prostate cancer cells. JV-1-38 evoked prompt Ca2+ signal in a dose-dependent way (1-10 microM) and induced early stage of apoptosis in LNCaP human prostate cancer cells at a concentration effective in suppression of cell proliferation (10 microM) peaking after 3 h. Unexpectedly, agonist GHRH(1-29)NH2, which elevates cytosolic free Ca2+ concentration in pituitary somatotrophs at nanomolar concentrations, failed to induce Ca2+ signal or apoptosis even at a 10-fold higher concentration (100 microM). However, agonist GHRH(1-29)NH2 inhibited JV-1-38-induced Ca2+ signals in a dose-dependent way without affecting the antagonist-induced apoptosis. Peptides unrelated to GHRH did not induce Ca2+ signals in LNCaP human prostate cancer cells. EDTA (10 mM) or nifedipine (10 microM) significantly reduced the Ca2+ signal and early stage of apoptosis induced by JV-1-38, supporting the view that the increase in intracellular Ca2+ in response to JV-1-38 occurs primarily through extracellular Ca2+ entry through voltage-operated Ca2+ channels. In conclusion, GHRH antagonists activate tumoral GHRH receptors and are able to induce apoptosis in LNCaP human prostate cancer cells through a Ca2+-dependent pathway. Treatment with GHRH antagonists may offer a new approach to the therapy of prostate and other hormone-sensitive cancers.
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PMID:Antagonist of growth hormone-releasing hormone induces apoptosis in LNCaP human prostate cancer cells through a Ca2+-dependent pathway. 1572 67

Circulating insulin-like growth factor-I (IGF-I) levels have been shown to be related to risk of prostate cancer in epidemiologic studies. While specific genetic loci responsible for interindividual variation in circulating IGF-I levels in normal men have not been identified, candidate genes include those involved in the growth hormone (GH)-IGF-I axis such as the hypothalamic factors GH releasing hormone (GHRH) and somatostatin and their receptors. To investigate the role of the GH-IGF-I axis on in vivo prostate carcinogenesis and neoplastic progression, we generated mice genetically predisposed to prostate cancer (the TRAMP model) to be homozygous for lit, a mutation that inactivates the GHRH receptor (GHRH-R) and reduces circulating levels of GH and IGF-I. The lit mutation significantly reduced the percentage of the prostate gland showing neoplastic changes at 35 weeks of age (P=0.0005) and was also associated with improved survival (P<0.01). These data provide an example of a germ line mutation that reduces risk in an experimental prostate carcinogenesis model. The results suggest that prostate carcinogenesis and progression may be influenced by germ line variation of genes encoding signalling molecules in the GH-IGF-I axis.
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PMID:A germ line mutation that delays prostate cancer progression and prolongs survival in a murine prostate cancer model. 1587 Jul 5

Bombesin/gastrin-releasing peptide (BN/GRP) antagonists RC-3940-II and RC-3940-Et, and growth hormone-releasing hormone (GHRH) antagonists MZ-J-7-118 and RC-J-29-18 inhibit the growth of human androgen-independent PC-3 and DU-145 prostate cancers in nude mice. Additive inhibitory effects were observed after treatment with both classes of analogs. In the present study, we investigated the effects of these antagonists on intracellular signalling pathways of protein kinase C (PKC), mitogen activated protein kinases (MAPK) and c-fos and c-jun oncogenes that are involved in tumour cell proliferation. In PC-3 tumours, antagonists of BN/GRP and GHRH decreased significantly the expression of PKC isoforms alpha (alpha), eta (eta) and zeta (zeta) and increased that of delta (delta) PKC protein. MAPK was not detectable. In DU-145 tumours, which constitutively express MAPK, all treatments strongly decreased the levels of p42/44 MAPK. Treatment with the antagonists tended to reduce m-RNA for c-jun in both tumour models. In proliferation assays in vitro, inhibitors of PKC and MAPK diminished growth of DU-145 and PC-3 cells. These findings suggest that antagonists of BN/GRP and GHRH inhibit the growth of androgen-independent prostate cancer by affecting intracellular signalling mechanisms of PKC, MAPK and c-jun.
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PMID:Inhibition of human androgen-independent PC-3 and DU-145 prostate cancers by antagonists of bombesin and growth hormone releasing hormone is linked to PKC, MAPK and c-jun intracellular signalling. 1629 Oct 86


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