UMLS:C0376358 - FACTA Search

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

The insulin-like growth factor (IGF) system has been shown to regulate prostate cancer cell growth in vitro and, possibly, in vivo. In this study we examined RNA expression of IGF ligands and their receptors in 23 paired benign and neoplastic prostate tissues. In addition to comparing gene expression of IGF ligands and receptors between benign and neoplastic tissue samples, we correlated IGF-I, IGF-II, IGFR-1, and IGFR-2 RNA levels in tumor samples with prognostic clinico-pathological parameters such as stage, grade, Gleason score, perineural or extraprostatic invasion. We found higher IGF-I RNA levels in benign vs. malignant tissues (p = 0.014), whereas IGF-II RNA expression was higher in tumors with high Gleason score (GS) (p = 0.045). Using the Spearman rank correlation test we also found a positive correlation between IGFR-2 RNA levels and GS (p = 0.01). No correlation was found between expression of IGF ligands and receptors and tumor grade, stage perineural invasion, or extraprostatic involvement. We conclude that differential expression of certain IGF system components may be important in the biology and clinical behavior of prostate cancer.
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PMID:Gene expression of insulin-like growth factors and receptors in neoplastic prostate tissues: correlation with clinico-pathological parameters. 1129 53

The preprostatectomy setting serves as a valuable clinical model for early developmental clinical trials for evaluating promising agents for chemoprevention. In the preprostatectomy model, study agents are administered between the diagnostic biopsy for prostate cancer and definitive therapy. The prostatic tissue that is available after prostatectomy allows for biomarker evaluation of all the components of the prostate, including the glandular epithelium, blood vessels, and the stroma. This provides an opportunity to study the reciprocal interactions between the stroma and the epithelium. Morphologic studies suggest that prostatic stromal cells play a critical role in affecting the growth and maturation of prostatic epithelium. Experimental studies in tissue culture show that carcinoma-associated stromal cells can promote prostatic carcinogenesis, and normal stromal cells may be able to inhibit prostatic carcinogenesis by inducing differentiation and decreasing the proliferation of the epithelium. Although the complex molecular mechanisms through which stroma modulates the epithelial cell phenotype remain to be elucidated, there are several well-characterized signaling pathways, such as for growth factors and steroid hormones, that are likely to contribute to the modulation of transformed epithelial cells. There is evidence of an association between increased serum levels of IGF-I and an increased risk of prostate cancer. The IGF system appears to play an important role in the development of prostate cancer by modulation of paracrine pathways, and also by modulation of the concentrations of different stromal and epithelial IGFBP, which are differentially expressed in the epithelium and stroma. Nerve growth factor is capable of stimulating a proliferative response via a high affinity Trk receptor present in normal and malignant prostate epithelia, and alternatively can mediate apoptosis via the low affinity p75NTR receptor that is progressively lost from the malignant prostate. As the role of each stromal element involved in carcinogenesis becomes further defined, these elements offer promising targets for new chemopreventive strategies.
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PMID:Preprostatectomy: A clinical model to study stromal-epithelial interactions. 1129 26

Insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3) possesses both growth-inhibitory and -potentiating effects on cells that are independent of IGF action and are mediated through specific IGFBP-3 binding proteins/receptors located at the cell membrane, cytosol, or nuclear compartments and in the extracellular matrix. We have here characterized transferrin (Tf) as one of these IGFBP-3 binding proteins. Human serum was fractionated over an IGFBP-3 affinity column, and a 70-kDa protein was eluted, sequenced, and identified (through database searching and Western immunoblot) as human Tf. Tf bound IGFBP-3 but had negligible affinity to the other five IGFBPs, and iron-saturated holo-Tf bound IGFBP-3 more avidly than unsaturated Tf. Biosensor interaction analysis confirmed that this interaction is specific and sensitive, with a high association rate similar to IGF-I, and suggested that binding occurs in the vicinity of the IGFBP-3 nuclear localization site. As an independent confirmation of this interaction, using a yeast two-hybrid system, we cloned Tf from a human liver complementary DNA library as an IGFBP-3 protein partner. Tf treatment blocked IGFBP-3-induced cell proliferation in bladder smooth muscle cells, and IGFBP-3-induced apoptosis in prostate cancer cells. In summary, we have employed a combination of techniques to demonstrate that Tf specifically binds IGFBP-3, and we showed that this interaction has important physiological effects on cellular events.
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PMID:Transferrin is an insulin-like growth factor-binding protein-3 binding protein. 1129 22

G-protein coupled receptor (GPCR) agonists such as neuropeptides activate the insulin-like growth factor-1 receptor (IGF-IR) or the serine-threonine protein kinase Akt, suggesting that neuropeptides-GPCR signaling can cross-communicate with IGF-IR-Akt signaling pathways. Neutral endopeptidase 24.11 (NEP) is a cell-surface peptidase that cleaves and inactivates the neuropeptides endothelin-1 (ET-1) and bombesin, which are implicated in progression to androgen-independent prostate cancer (PC). We investigated the mechanisms of NEP regulation of neuropeptide-mediated cell survival in PC cells, including whether neuropeptide substrates of NEP induce phosphorylations of IGF-IR and Akt in PC cells. Western analyses revealed ET-1 and bombesin treatment induced phosphorylation of IGF-IRbeta and Akt independent of IGF-I in TSU-Pr1, DU145, and PC-3 PC cells, which lack NEP expression, but not in NEP-expressing LNCaP cells. Recombinant NEP and induced NEP expression in TSU-Pr1 cells using a tetracycline-repressive expression system inhibited ET-1-mediated phosphorylation of IGF-IRbeta and Akt, and blocked the protective effects of ET-1 against apoptosis induced by serum starvation. Incubation of TSU-Pr1 cells with specific kinase inhibitors together with ET-1 or bombesin showed that IGF-IR activation is required for neuropeptide-induced Akt phosphorylation, and that neuropeptide-induced Akt activation is predominantly mediated by Src and phosphatidylinositol 3-kinase but not by mitogen-activated protein kinase or protein kinase C. These data show that the neuropeptides ET-1 and bombesin stimulate ligand-independent activation of the IGF-IR, which results in Akt activation, and that this cross-communication between GPCR and IGF-IR signaling is inhibited by NEP.
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PMID:Neutral endopeptidase inhibits neuropeptide-mediated transactivation of the insulin-like growth factor receptor-Akt cell survival pathway. 1130 83

Recent theories propose that a Western lifestyle may increase cancer risk through alterations in the metabolism of insulin and insulin-like growth factors (IGF: McKeown-Eyssen, 1994; Giovannucci, 1995; Kaaks, 19%; Werner & LeRoith, 1996). Insulin regulates energy metabolism, and increases the bioactivity of IGF-I, by enhancing its synthesis. and by decreasing several of its binding proteins (IGFBP; IGFBP-1 and -2). Insulin and IGF-I both stimulate anabolic processes as a function of available energy and elementary substrates (e.g. amino acids). The anabolic signals by insulin or IGF-I can promote tumour development by inhibiting apoptosis, and by stimulating cell proliferation. Furthermore, both insulin and IGF-I stimulate the synthesis of sex steroids, and inhibit the synthesis of sex hormone-binding globulin (SFIBG), a binding protein that regulates the bioavailability of circulating sex steroids to tissues. The present paper reviews epidemiological findings relating the risk of cancers of the colo-rectum, pancreas, breast, endometrium and prostate to body size (obesity, height) and physical activity, and discusses the relationships between obesity and physical activity and plasma levels of insulin, IGF-I and IGFBP. Subsequent sections review epidemiological findings relating cancer risk to indices of chronic hyperinsulinaemia, and to plasma levels of IGF-I and IGFBP. Conclusions are that chronic hyperinsulinaemia may be a cause of cancers of the colon, pancreas and endometrium, and also possibly of the breast. On the other hand, elevated plasma IGF-I, as total concentrations or relative to levels of IGFBP-3, appears to be related to an increased risk of prostate cancer, breast cancer in young women, and possibly cob-rectal cancer. For cancers of the endometrium, breast and prostate, these findings are discussed in the context of relationships between insulin and IGF-I and levels of bioavailable sex steroids.
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PMID:Energy balance and cancer: the role of insulin and insulin-like growth factor-I. 1131 Apr 28

LNCaP cells are human prostatic cancer cells that have a frame-shift mutation of the tumor suppressor gene PTEN and do not express the insulin receptor substrate-1 (IRS-1), a major substrate of the type 1 insulin-like growth factor receptor (IGF-IR). Ectopic expression of IRS-1 in LNCaP cells increases cell adhesion and decreases cell motility by an IGF-I-independent mechanism. We show now that these effects of IRS-1 are accompanied by serine phosphorylation of IRS-1 and are inhibited by inhibitors of phosphatidylinositol 3-kinase (PI3K). We have confirmed the requirement for PI3K activity and serine phosphorylation by the use of IRS-1 mutants, expressed in LNCaP cells. Serine phosphorylation inhibits IGF-I-induced tyrosyl phosphorylation of IRS-1, which is restored by the expression of wild-type PTEN or by inhibition of PI3K activity. Finally, IRS-1 in LNCaP cells co-immunoprecipitates with integrin alpha 5 beta 1, and the association is again IGF-I-independent. We conclude that in LNCaP cells, IRS-1 is serine phosphorylated by PI3K, generating effects that are different, and even opposite, from those generated by IGF-I.
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PMID:Mechanisms of regulation of cell adhesion and motility by insulin receptor substrate-1 in prostate cancer cells. 1131 80

Insulin-like growth factors (IGFs) have potent mitogenic and antiapoptotic effects on prostate epithelial cells. Through modulation of IGF bioactivity and other mechanisms, IGF-binding proteins (IGFBPs) also have growth-regulatory effects on prostate cells. Recently, IGF-I and IGFBP-3 have been implicated in prostate cancer risk among Western populations. To assess whether IGF-I, IGF-II, IGFBP-1, or IGFBP-3 are also associated with prostate cancer in a low-risk population, we measured plasma levels of these factors among 128 newly diagnosed prostate cancer cases and 306 randomly selected population controls in Shanghai, China. Relative to the lowest quartile of IGF-I levels, men in the highest quartile had a 2.6-fold higher prostate cancer risk, with a significant trend [odds ratio (OR) = 2.63; 95% confidence interval (95% CI) = 1.19-5.79; P(trend) = 0.01]. In contrast, men in the highest quartile of IGFBP-3 levels had a 46% decreased risk relative to the lowest quartile (OR = 0.54; 95% CI = 0.26-1.15; P(trend) = 0.08). A similar but less distinct result was observed for IGFBP-1 (OR = 0.60; 95% CI = 0.31-1.17; P(trend) = 0.25). Men in the highest quartile for the IGF-I:IGFBP-3 molar ratio (an indirect measure of free IGF-I) had a 2.5-fold higher risk compared with the lowest quartile (OR = 2.51; 95% CI = 1.32-4.75, P(trend) < 0.001). These associations were more pronounced after adjustment for serum 5alpha-androstane-3alpha,17beta-diol glucuronide and sex hormone-binding globulin levels. There was no significant association with IGF-II levels. Our findings in a low-risk population provide evidence that IGF-I, IGFBP-3, and IGFBP-1 are determinants of prostate cancer and indicate that additional studies are needed to evaluate their effects on ethnic and geographic incidence differentials and to elucidate carcinogenic mechanisms.
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PMID:Insulin-like growth factors and prostate cancer: a population-based case-control study in China. 1135 50

Operating through the vitamin D receptor (VDR), vitamin D inhibits prostate cancer growth and increases insulin-like growth factor binding protein (IGFBP) expression, suggesting that the vitamin D and insulin-like growth factor (IGF) regulatory systems may operate together to affect prostate cancer. Among 191 newly diagnosed prostate cancer cases and 304 randomly selected population controls in Shanghai, China, we found no significant association between the BsmI or FokI VDR gene polymorphisms and prostate cancer risk. However, we found that among men with the ff FokI genotype, those in the highest tertile of plasma IGFBP-3 had a decreased risk versus those in the lowest tertile (odds ratio, 0.14; 95% confidence interval, 0.04-0.56; P(trend) < 0.01), whereas among men with the FF and Ff genotypes, IGFBP-3 was not associated with risk. Similarly, IGFBP-1 was inversely associated with prostate cancer risk only among men with the ff FokI genotype (odds ratio, 0.25; 95% confidence interval, 0.07-0.85; P(trend) = 0.02). No such FokI genotype-specific effects were observed for IGF-I or IGF-II. Our findings in a low-risk population suggest that the IGF and vitamin D regulatory systems may interact to affect prostate cancer risk. Larger studies are needed to confirm these findings and clarify the underlying mechanisms.
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PMID:Vitamin D receptor gene polymorphisms, insulin-like growth factors, and prostate cancer risk: a population-based case-control study in China. 1138 55

Androgen deprivation therapies for metastatic prostate cancer are useful initially, but progression to androgen independence usually results in relapse within 2 years. The molecular mechanisms underlying the clinically important transition from androgen dependence to androgen independence are poorly described. Several lines of investigation have suggested that insulin-like growth factors (IGFs) are involved in the biology of prostate cancer, but little is known about their relevance to progression to androgen independence. We used three in vivo models of androgen-dependent (AD) human prostate cancer to study this issue. Progression to androgen-independent (AI) growth was associated with a 60-fold increase in expression of IGF-I mRNA in LAPC-9 xenografts and a 28-fold increase in IGF-I expression in LNCAP xenografts, relative to the initial AD neoplasms. IGF type I receptor (IGF-IR) mRNA levels were approximately 2.5-fold and approximately 5-fold higher, respectively, in AI LAPC-9 and LNCaP tumors compared with the original AD neoplasms. AI growth of these xenografts was also associated with significant reductions in IGF binding protein-3 expression. LAPC-4 xenografts, which previously have been shown to exhibit molecular pathology related to HER-2/neu expression with progression to AI, showed relatively minor changes in expression of the genes investigated, but we nevertheless found evidence of increased IGF-IR phosphorylation with progression to androgen independence in this model. Taken together with prior observations, our results suggest that deregulation of expression of genes related to any one of several critical receptor tyrosine kinase regulatory systems, including IGF signaling, may confer androgen independence.
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PMID:In vivo progression of LAPC-9 and LNCaP prostate cancer models to androgen independence is associated with increased expression of insulin-like growth factor I (IGF-I) and IGF-I receptor (IGF-IR). 1150 82

Prostate cancer is the most diagnosed invasive malignancy in males. Androgens and oestrogens have been implicated in the pathogenesis of prostate cancer. We report herein that the pure anti-oestrogen ICI 182,780 (ICI) reduces Ki-67 labelling index and IGF-I receptor levels in rat prostate. Increase of IGF-I mRNA and IGF-binding protein 3 (IGFBP-3) accumulation occur without any effect on prostate weight. Finasteride significantly decreases prostate weight and inhibits IGF-I gene expression. IGFBP-3 mRNA, Akt and phospho-Akt are not affected by finasteride. Co-administration of ICI plus finasteride reduces prostate weight by approximately 50% and causes acinar dilation with decreased luminal epithelial cell thickness. The acinar epithelial cells became atrophic and inactive with minimal cytoplasm. We also demonstrate a synergistic effect of ICI and finasteride on induction of IGFBP-3 accumulation and inhibition of Akt phosphorylation. Because the IGF and IGFBP-3 system plays an important role in prostate epithelial cell proliferation, apoptosis and tumour progression, the inhibitory effects of finasteride and ICI on IGF system may contribute to their anti-proliferative activity. These observations support a potential use of ICI in conjunction with finasteride in the prevention and/or treatment of prostate cancer.
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PMID:Co-administration of finasteride and the pure anti-oestrogen ICI 182,780 act synergistically in modulating the IGF system in rat prostate. 1157 95

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