Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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

Four transplantable cell lines (PA-I, II, III, and IV) derived from four Lobund-Wistar (L-W) rats that manifested spontaneous prostate cancer have demonstrated metastatic capacity in visceral organs. Interestingly, PA-III cells, when deposited over the scapula or calvarium of the Lobund-Wistar rat, could produce lytic and blastic reactions on rat skeleton. Since growth factors and growth factor receptors have been implicated in bone remodeling, cancer biology, and metastatic growth of cancer cells, we have examined 1) the effects of insulin and insulin-like growth factors (IGF-I and IGF-II) on the proliferation of PA-III cells; and 2) the presence of specific receptors for these peptides. IGF-I (0.5 to 100 ng/ml), IGF-II (0.5 to 100 ng/ml), and insulin (0.5 to 10 micrograms/ml) stimulated tritiated thymidine uptake and increased the number of PA-III cells in culture. Receptor studies demonstrated the presence of specific bindings sites for IGF-I and II but not for insulin. The number and affinity of the receptor sites were: IGF-I (nb = 675 fmol/100 g protein, Kd = 0.56 nmol) and IGF-II (nb = 225 fmol/100 g protein, Kd = 0.71 nmol). Molecular characterization of IGF binding sites by polyacrylamide gel electrophoresis under denaturing conditions indicated only the presence for the type I IGF receptor. The presence of the IGF-I receptor and the absence of IGF-II and insulin receptors are discussed in relation to the capacity of PA-III cells to produce bone lesions on the L-W rat.
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PMID:Mitogenic effects of insulin and insulin-like growth factors on PA-III rat prostate adenocarcinoma cells: characterization of the receptors involved. 166 15

Prostate cancer and benign prostate hyperplasia (BPH) are major public health problems. Prostate epithelial cell proliferation is regulated by insulin-like growth factor I (IGF-I) which is mitogenic and anti-apoptotic, and IGF binding protein 3 (IGFBP-3) which is an apoptotic agent in these cells. We demonstrate that the 1,25(OH)2D3 and its analog EB1089-induced growth inhibition was associated with increased IGFBP-3 mRNA abundance, IGFBP-3 mRNA stability, IGFBP-3 protein accumulation, and decreased IGF-II gene expression. Anti-IGF-II antibody and exogenous recombinant human IGFBP-3 inhibit PC-3 cell proliferation. The results document the inhibitory effects of 1,25(OH)2D3 and EB1089 on the IGF system of mitogens in prostate cancer cells, and suggest a potential therapeutic use of EB1089 in treatment of BPH and prostate cancer.
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PMID:Regulation of insulin-like growth factor (IGF) II and IGF binding protein 3 autocrine loop in human PC-3 prostate cancer cells by vitamin D metabolite 1,25(OH)2D3 and its analog EB1089. 962 15

The protein product of the novH oncogene, a member of the CCN family, is structurally related to the insulin-like growth factor (IGF) binding proteins (IGFBPs). We have characterized aspects of structure, function, and distribution of this protein, which, as IGFBP-related protein 3 (IGFBP-rP3), is a proposed member of the IGFBP Superfamily. Affinity cross-linking experiments performed with baculovirus synthesized recombinant human IGFBP-rP3 established that rhIGFBP-rP3 binds IGF-I, IGF-II, and insulin with low affinity. Specificity of binding was shown by competitive cross-linking experiments; binding to IGF-I and -II was also demonstrated by nondenaturing Western ligand blots. Northern blot analysis indicated the presence of IGFBP-rP3 messenger RNA (mRNA) in a broad range of human tissues. Western immunoblotting studies, using a polyclonal rabbit anti-rhIGFBP-rP3 antibody, demonstrated that IGFBP-rP3 protein is synthesized in vitro by several breast and prostate cancer cell lines: Hs578T, PC3, P69, and LNCaP cells. Western immunoblotting studies of human biological fluids identified that IGFBP-rP3 was present in normal serum, pregnancy serum, serum from patients with growth hormone receptor deficiency, cerebrospinal fluid, amniotic fluid, peritoneal fluid, and follicular fluid, while IGFBP-rP3 fragments were identified in cerebrospinal fluid, amniotic fluid, and prepubertal and pubertal urine samples. Our studies demonstrate that IGFBP-rP3 exhibits IGF binding, albeit at low affinity, and IGFBP-rP3 thus merits inclusion in the IGFBP Superfamily. The low affinity IGF binding suggests that IGFBP-rP3 may act primarily independently of the IGFs. The synthesis of IGFBP-rP3 by several malignant cell lines and its presence in human biological fluids suggest that this protein possesses other interesting roles, potentially in cell growth regulation.
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PMID:Binding properties and distribution of insulin-like growth factor binding protein-related protein 3 (IGFBP-rP3/NovH), an additional member of the IGFBP Superfamily. 1008 1

Recent case-control studies have found a 7-8% increase in the serum levels of insulin-like growth factor (IGF)-I in patients with prostate cancer (CaP), the most frequently diagnosed cancer in men. We hereby review what is currently known about growth hormone (GH) and the IGF axis in CaP, take a closer inspection of the studies published to date reporting IGF-I levels in CaP patients, and derive implications for the future medical management of patients receiving trophic hormone therapies as well as those at risk for developing CaP. The role of GH in controlling prostate growth and carcinogenesis is still unclear from animal studies and human disease patterns. However, multilayered perturbations of the IGF axis, including the autocrine production of IGFs, IGF binding proteins (IGFBPs) and IGFBP proteases, such as prostate-specific antigen, have been identified in CaP cells and tissues. Interestingly, IGFBP-3 is a potent inhibitor of prostatic IGF action and also mediates prostate apoptosis via an IGF-independent mechanism. Serum IGFBP-3 levels have been identified to be negatively correlated to the risk of CaP. Notably, GH therapy raises both IGF-I and IGFBP-3 levels in serum. Conclusions based on the studies of IGF-I levels in CaP patients are affected by both the populations studied and the types of IGF-I assay employed. While the studies do indicate an association between serum IGF-I levels and CaP risk, causality has not been established. Thus, serum IGF-I level may actually be a confounding variable, serving as a marker for local prostatic IGF-I production. Increased GH levels as seen in acromegaly have been associated with benign prostatic hyperplasia but not with CaP. Thus, serum IGF-I may lead to an ascertainment bias among younger men with benign prostatic hyperplasia who are more likely to present with prostatic symptoms and have subclinical CaP diagnosed. Should serum IGF-I levels be proven to play a causal role in the pathogenesis of CaP, interpreting the risk associated with therapies such as GH must take into account both the duration of exposure and the risk magnitude associated with the degree of serum IGF-I elevation. Since GH-deficient patients often have a subnormal IGF-I serum level, which normalizes on therapy, their CaP risk on GH therapy probably does not increase substantially above that of the normal population. Until further research in the area dictates otherwise, ongoing surveillance and routine monitoring of IGF-I and IGFBP-3 levels in GH recipients must become standard of care.
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PMID:Growth hormone and prostate cancer: guilty by association? 1044 74

Insulin-like growth factor (IGF)-I is an important mitogen required by some cell types to progress from the G1 phase to the S phase of the cell cycle. IGF binding proteins (IGFBPs) can have opposing actions, in part by binding IGF-I, but also by direct inhibitory effects on target cells. As mitogens and anti-apoptotic agents, IGFs may be important in carcinogenesis, possibly by increasing the risk of cellular transformation by enhancing cell turnover. Indeed, many types of neoplastic cells express or overexpress IGF-I receptors, which stimulate mitogenesis when activated by IGF-I in vitro. In vivo, tissue IGF bioactivity is determined not only by circulating IGF-I and IGFBP levels, but also by local production of IGFs, IGFBPs, and possibly IGFBP proteases that enhance IGF-I availability by cleaving IGFBPs. Because determinants of tissue IGF bioactivity appear to be regulated in parallel with circulating IGF-I level, it is reasonable to hypothesize that the substantial intraindividual variability in circulating levels of IGF-I and IGFBP-3 may be important in determining risk of some cancers. In recent epidemiologic studies, relatively high plasma IGF-I and low IGFBP-3 levels have been independently associated with greater risk of prostate cancer in men, breast cancer among premenopausal women, and colorectal adenoma and cancer in men and women and possibly lung cancer. These include prospective data from the Physicians' Health Study and the Nurses' Health Study. In general, two- to fourfold elevated risks have been observed for prostate cancer in men in the top quartile of IGF-I relative to those in the bottom quartile, and low levels of IGFBP-3 were associated with an approximate doubling of risk. For breast cancer, an association with IGF-I for postmenopausal women was not apparent, but strong associations were observed for premenopausal cases in the Nurses' Health Study. Further study is needed to confirm this subgroup finding in women. Recent data also indicate that high IGF-I and low IGFBP-3 increase risk of colorectal cancer and large or villous adenomas. Of note, for colorectal neoplasia, fourfold elevated risks were observed in men and women with low IGFBP-3, whereas high IGF-I was associated with a doubling of risk. These emerging epidemiologic data indicate that high levels of IGF-I and low levels of IGFBP-3 are associated with an increased risk of at least several types of carcinoma that are common in economically developed countries. Further study is required to determine the clinical relevance of these findings.
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PMID:Insulin-like growth factor-I and binding protein-3 and risk of cancer. 1059 42

Insulin-like growth factor-1 (IGF-1) is an important mitogen, and IGF binding protein-3 (IGFBP-3) has opposing effects. Acromegalics, who have abnormally elevated levels of IGF-1, are at increased risk of colorectal tumors. Recent studies have found that IGF-1 levels correlate with risk of prostate cancer and colorectal cancer in men, premenopausal breast cancer in women, and lung cancer in men and women. We examined whether prediagnostic plasma levels of IGF-1 and IGFBP-3 influence risk of colorectal cancer and adenoma in women. From 1989 to 1990, a total of 32,826 women from the Nurses' Health Study provided blood specimens that were archived in liquid nitrogen. During 6 years of follow-up from 1989 to 1994, we documented 79 new cases of colorectal cancer, 90 cases of intermediate/late-stage adenoma (> or =1 cm or tubulovillous/villous histology), and 107 cases of early-stage adenoma (<1 cm and tubular histology). After matching controls (2:1 for cancers and 1:1 for adenomas) to cases by age, month of blood draw, fasting status, and indication for endoscopy (for adenoma controls), plasma IGF-1 and IGFBP-3 levels were measured. Controlling for IGFBP-3 level, relative to women in the low tertile of IGF-1, those in the high tertile were at elevated risk of intermediate/late-stage colorectal neoplasia adenoma [multivariate relative risk (RR), 2.78; 95% confidence interval (CI), 0.76-9.76] and cancer (RR, 2.18; 95% CI, 0.94-5.08). Controlling for IGF-1 level, relative to women in the low tertile of IGFBP-3, women in the high tertile of IGFBP-3 were at lower risk of intermediate/late-stage colorectal adenoma (RR, 0.28; 95% CI, 0.09-0.85) and cancer (RR, 0.28; 95% CI, 0.10-0.83). Neither IGF-1 nor IGFBP-3 had any appreciable relation with early-stage adenoma. These analyses indicate that high levels of circulating IGF-1 and particularly low levels of IGFBP-3 are associated independently with an elevated risk of large or tubulovillous/villous colorectal adenoma and cancer.
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PMID:A prospective study of plasma insulin-like growth factor-1 and binding protein-3 and risk of colorectal neoplasia in women. 1079 77

A chemoprevention (CP) strategy has evolved for conducting efficient clinical trials for prostate cancer (PCa) prevention. It integrates five key components, including agents, biomarkers, cohorts, designs, and endpoints. The rationale for the CP strategy relates to the natural history of prostate cancer. There is a wide array of natural and synthetic agents that hold promise for inhibiting, reversing, or modulating the transition from normal to precancer and from precancer to cancer. These agent classes include antiandrogens, antiestrogens, phytoestrogens, antioxidants, anti-inflammatory (proapoptotic) agents, antiproliferation/antidifferentiation agents, signal transduction modulators of receptor tyrosine kinase and ras farnesylation, antiangiogenesis agents, insulinlike growth factor (IGF)-1, peroxisome proliferator-activator receptor modulators (-gamma and -delta), and gene-based interventions. Biomarkers and endpoints are guided by the level of evidence required (eg, phase 1, 2, 3). Two candidate surrogate endpoints (SE) based on histology are high-grade prostatic intraepithelial neoplasia (HGPIN) and computer-assisted image analysis of dysplastic lesions. Phase 1 trials use standard endpoints of safety, pharmacokinetics and limited pharmacodynamics. Phase 2 trials use endpoints of modulation of biomarkers and correlation with histology. Phase 3 trials use endpoints of clinical benefit, such as cancer incidence reduction and quality of life. Validation of a biomarker as a SE involves correlation of the biomarker with clinical benefit. Cohorts (target populations) for phase 2/3 trials include the general population of men over age 50 with a normal prostate-specific antigen (PSA), subjects with a strong family history of PCa, subjects with elevated PSA/negative biopsy, and subjects with HGPIN/negative biopsy. These at-risk populations reflect key individual risk factors (age, race, serum PSA [free/total]; serum IGF-1/IGF binding protein (IGFBP)-3; 1, 25(OH)(2) D3; family history of PCa; carriers of PCa susceptibility genes [ELAC2, CYP3A4, SRD5A2, etc.]; and histology such as atypia and HGPIN) that could be combined into a multivariate risk model for PCa. The probability of cancer risk (recurrence) is a key factor that impacts on the clinical trial design (power, sample size, and primary endpoint). Multivariate predictive mathematical models for biochemical recurrence after radical prostatectomy by decreasing sample size and time to clinical outcomes maximize trial efficiency and identify the patients most likely to benefit from secondary prevention. The two large primary prevention trials, Prostate Cancer Prevention Trial/Seleninium and Vitamin E Chemoprevention Trial (PCPT/ SELECT), in low- and average-risk subjects have sample sizes of 18,000 to 32,000, with a treatment duration of 7 years to detect a 25% reduction in biopsy-proven PCa. Subjects with HGPIN have the highest known cancer risk (approximately 50% at 3 years), and thus require a small sample size (n = 450) to detect a 33% reduction in cancer incidence. A schema involving three sequential trials for agent registration is described. In summary, a CP strategy that incorporates well-defined agents, clinical and validated SE, and high-risk cohorts defined by genetic and acquired risk factors in a series of well-designed randomized controlled trials provides an efficient pathway for evaluating and approving new agents for PCa prevention.
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PMID:Prostate cancer chemoprevention: Strategies for designing efficient clinical trials. 1129 33

An inverse association has been observed between dietary intake of lycopene and the risk of prostate cancer. We investigated the effects of lycopene supplementation in patients with prostate cancer. Twenty-six men with newly diagnosed, clinically localized (14 T(1) and 12 T(2)) prostate cancer were randomly assigned to receive 15 mg of lycopene (n = 15) twice daily or no supplementation (n = 11) for 3 weeks before radical prostatectomy. Biomarkers of differentiation and apoptosis were assessed by Western blot analysis on benign and malignant parts of the prostate gland. Prostatectomy specimens were entirely embedded, step-sectioned, and evaluated for pathological stage, Gleason score, volume of cancer, and extent of high-grade prostatic intraepithelial neoplasia. Plasma levels of lycopene, insulin-like growth factor-1 (IGF-1), IGF binding protein-3, and prostate-specific antigen were measured at baseline and after 3 weeks of supplementation or observation. Eleven (73%) subjects in the intervention group and two (18%) subjects in the control group had no involvement of surgical margins and/or extra-prostatic tissues with cancer (P = 0.02). Twelve (84%) subjects in the lycopene group and five (45%) subjects in the control group had tumors <4 ml in size (P = 0.22). Diffuse involvement of the prostate by high-grade prostatic intraepithelial neoplasia was present in 10 (67%) subjects in the intervention group and in 11 (100%) subjects in the control group (P = 0.05). Plasma prostate-specific antigen levels decreased by 18% in the intervention group, whereas they increased by 14% in the control group (P = 0.25). Expression of connexin 43 in cancerous prostate tissue was 0.63 +/- 0.19 absorbance in the lycopene group compared with 0.25 +/- 0.08 in the control group (P = 0.13). Expression of bcl-2 and bax did not differ significantly between the two study groups. IGF-1 levels decreased in both groups (P = 0.0002 and P = 0.0003, respectively). The results suggest that lycopene supplementation may decrease the growth of prostate cancer. However, no firm conclusions can be drawn at this time because of the small sample size.
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PMID:Phase II randomized clinical trial of lycopene supplementation before radical prostatectomy. 1148 52

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

Insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3) can stimulate apoptosis and inhibit cell proliferation directly and independently of binding IGFs or indirectly by forming complexes with IGF-I and IGF-II that prevent them from activating the IGF-I receptor to stimulate cell survival and proliferation. To date, IGF-independent actions only have been demonstrated in a limited number of cells that do not synthesize or respond to IGFs. To assess the general importance of IGF-independent mechanisms, we have generated human IGFBP-3 mutants that cannot bind IGF-I or IGF-II by substituting alanine for six residues in the proposed IGF binding site, Ile(56)/Tyr(57)/Arg(75)/Leu(77)/Leu(80)/Leu(81), and expressing the 6m-hIGFBP-3 mutant construct in Chinese hamster ovary cells. Binding of both IGF-I and IGF-II to 6m-hIGFBP-3 was reduced >80-fold. The nonbinding 6m-hIGFBP-3 mutant still was able to inhibit DNA synthesis in a mink lung epithelial cell line in which inhibition by wild-type hIGFBP-3 previously had been shown to be exclusively IGF-independent. 6m-hIGFBP-3 only can act by IGF-independent mechanisms since it is unable to form complexes with the IGFs that inhibit their action. We next compared the ability of wild-type and 6m-hIGFBP-3 to stimulate apoptosis in serum-deprived PC-3 human prostate cancer cells. PC-3 cells are known to synthesize and respond to IGF-II, so that IGFBP-3 could potentially act by either IGF-dependent or IGF-independent mechanisms. In fact, 6m-hIGFBP-3 stimulated PC-3 cell death and stimulated apoptosis-induced DNA fragmentation to the same extent and with the same concentration dependence as wild-type hIGFBP-3. These results indicate that IGF-independent mechanisms are major contributors to IGFBP-3-induced apoptosis in PC-3 cells and may play a wider role in the antiproliferative and antitumorigenic actions of IGFBP-3.
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PMID:Insulin-like growth factor (IGF)-binding protein-3 mutants that do not bind IGF-I or IGF-II stimulate apoptosis in human prostate cancer cells. 1178 19


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