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)

We previously reported that supplementation of a cationic liposome with transferrin (Tf) greatly enhanced lipofection efficiency (P.-W. Cheng, Hum. Gene Ther. 1996;7:275-282). In this study, we examined the efficacy of p53 and PTEN tumor suppressor gene therapy in a mouse xenograft model of human prostate PC-3 carcinoma cells, using a vector consisting of dimyristoyloxypropyl-3-dimethylhydroxyethyl ammonium bromide (DMRIE)-cholesterol (DC) and Tf. When the volume of the tumors grown subcutaneously in athymic nude mice reached 50-60 mm(3), three intratumoral injections of the following four formulations were performed during week 1 and then during week 3: (1) saline, (2) DC + Tf + pCMVlacZ, (3) DC + Tf + pCMVPTEN, and (4) DC + Tf + pCMVp53 (standard formulation). There was no significant difference in tumor volume and survival between group 1 and group 2 animals. As compared with group 1 controls, group 3 animals had slower tumor growth during the first 3 weeks but thereafter their tumor growth rate was similar to that of the controls. By day 2 posttreatment, group 4 animals had significantly lower tumor volume relative to initial tumor volume as well as controls at the comparable time point. Also, animals treated with p53 survived longer. Treatment with DC, Tf, pCMVp53, DC + pCMVp53, or Tf + pCMVp53 had no effect on tumor volume or survival. Expression of p53 protein and apoptosis were detected in tumors treated with the standard formulation, thus associating p53 protein expression and apoptosis with efficacy. However, p53 protein was expressed in only a fraction of the tumor cells, suggesting a role for bystander effects in the efficacy of p53 gene therapy. We conclude that intratumoral gene delivery by a nonviral vector consisting of a cationic liposome and Tf can achieve efficacious p53 gene therapy of prostate cancer.
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PMID:p53 and PTEN/MMAC1/TEP1 gene therapy of human prostate PC-3 carcinoma xenograft, using transferrin-facilitated lipofection gene delivery strategy. 1193 74

Understanding the molecular etiology of prostate cancer (CaP) progression is paramount for broadening current diagnostic and therapeutic modalities. Current interest in the role of wnt pathway signaling in prostate tumorigenesis was generated with the finding of beta-catenin mutation and corresponding nuclear localization in primary lesions. The recent finding of beta-catenin-induced enhancement of androgen receptor (AR) function potentially ties beta-catenin to key regulatory steps of prostate cell growth, differentiation, and transformation. By immunohistological analysis of metastatic tumors, we detected nuclear beta-catenin in 20% of lethal CaP cases, suggesting a more common role for beta-catenin in advanced disease than would be predicted by its mutation rate. Interestingly, beta-catenin nuclear localization was found to occur concomitantly with androgen-induced regrowth of normal rat prostate. These in vivo observations likely implicate beta-catenin involvement in both normal and neoplastic prostate physiology, thus prompting our interest in further characterizing modes of beta-catenin signaling in prostate cells. Extending our previous findings, we demonstrate that transient beta-catenin over-expression stimulates T cell factor (TCF) signaling in most CaP cell lines. Further, this activity is not subject to cross-regulation by phosphoinositide-3-kinase (PI3-K)/Akt signaling, a stimulatory pathway often upregulated in CaP upon PTEN inactivation. Consistent with a previous report, we observed that transient beta-catenin over-expression enhances AR-mediated transcription off two natural target gene promoters. However, we were unable to recapitulate beta-catenin-induced stimulation of ectopically expressed AR in AR-negative cells, suggesting that other AR-associated factors are required for this activity. Although LNCaP cells are capable of this mode of AR co-stimulation, stable expression of mutant beta-catenin did not alter their proliferative response to androgen. In total, our characterization of beta-catenin signaling in CaP reveals the complex nature of its activity in prostate tissue, indicating that beta-catenin potentially contributes to multiple stimulatory inputs required for disease progression.
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PMID:In vitro evidence for complex modes of nuclear beta-catenin signaling during prostate growth and tumorigenesis. 1196 41

The type 1 insulin-like growth factor receptor (IGF1R) mediates tumor cell growth, adhesion, and protection from apoptosis. High plasma IGF-I levels predispose to prostate cancer, but there is no consensus regarding IGF1R expression in primary and metastatic prostate cancer. Recent studies in a human cell line and a mouse model suggest that metastatic prostate cancer cell detachment may be favored by impairing cadherin function via loss of expression of insulin receptor substrate-1 (IRS-1), the principal IGF1R docking molecule. This may be accompanied by PTEN mutation, reactivating a key antiapoptotic pathway, and by IGF1R down-regulation to prevent Shc-mediated differentiation. We studied IGF1R expression in 54 samples of primary prostate tissue including 44 archival and 10 prospectively collected biopsies. We performed semiquantitative immunostaining for the IGF1R, IRS-1, and PTEN, and in situ hybridization for IGF1R. The IGF1R was significantly up-regulated at the protein and mRNA level in primary prostate cancer compared with benign prostatic epithelium. There was a trend toward increased expression of IRS-1 in the malignant biopsies. We also measured IGF1R, IRS-1, and PTEN expression in 12 paired biopsies of primary prostate cancer and subsequent bone metastases. In four cases, IGF1R and IRS-1 levels were lower in the metastases than in the primary tumors. Three of these metastases also lacked significant PTEN staining, compatible with findings in the model systems described above. However, this pattern was relatively uncommon, and 8 of 12 cases expressed detectable IGF1R and IRS-1 in both primary and metastatic biopsies. These findings challenge earlier reports of IGF1R down-regulation in metastatic disease and reinforce the importance of the IGF1R in prostate cancer biology.
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PMID:Expression of the type 1 insulin-like growth factor receptor is up-regulated in primary prostate cancer and commonly persists in metastatic disease. 1201 76

Not since the discovery of p53 has another molecule received as much attention as PTEN. In the 5 years since the discovery of PTEN, encoding a dual specificity phosphatase tumor suppressor on 10q23, it has been shown to be a susceptibility gene for an inherited cancer syndrome, Cowden syndrome, and for several developmental disorders; it has been shown to play a prominent role in normal murine and human development; and it has been shown to be instrumental in cell cycle arrest, apoptosis, and/or possibly cell migration and cytoskeletal affairs. Initial work on cancer cell lines had suggested that PTEN caused every type of cancer because it was reported that a relatively high frequency of a variety of cancer cell lines, whether derived from solid tumors or hematological malignancies, had homozygous or compound heterozygous genetic alterations involving PTEN. Such data, together with the germ-line human and murine model data, suggested that PTEN mutations occurred "early" in sporadic tumorigenesis. However, subsequent painstaking work in noncultured primary tumors and in careful in vitro overexpression studies over the last 4 years demonstrated that the mechanism of PTEN inactivation can be varied and might be cell type dependent. Furthermore, apart from sporadic endometrial carcinoma, PTEN alteration in noncultured sporadic neoplasias likely occurs "late," promoting progression and metastasis. The article by Davies et al. (Clin Cancer Res., 8: 1904-1914, 2002) sheds light on all of these issues when they report on data that derive from a "triple threat" strategy, i.e., in vitro, in vivo, and ex vivo, to demonstrate that adenoviral infection of PTEN into PTEN-null PC3 prostate cancer cell lines results in decreased metastatic potential without significantly altering tumor size via the predominant mechanism of G(1) cell cycle arrest but not apoptosis.
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PMID:The expanding role of PTEN in neoplasia: a molecule for all seasons? Commentary re: M. A. Davies, et al., Adenoviral-mediated expression of MMAC/PTEN inhibits proliferation and metastasis of human prostate cancer cells. Clin. Cancer Res., 8: 1904-1914, 2002. 1206 Jun 35

PI3K/Akt plays a critical role in prostate cancer cell growth and survival. Recent studies have shown that the effect of PI3K/Akt in prostate cells is mediated through androgen signaling. The PI3K inhibitor, LY294002, and a tumor suppressor, PTEN, negatively regulate the PI3K/Akt pathway and repress AR activity. However, the molecular mechanisms whereby PI3K/Akt and PTEN regulate the androgen pathway are currently unclear. Here, we demonstrate that blocking the PI3K/Akt pathway reduces the expression of an endogenous AR target gene. Moreover, we show that the repression of AR activity by LY294002 is mediated through phosphorylation and inactivation of GSK3beta, a downstream substrate of PI3K/Akt, which results in the nuclear accumulation of beta-catenin. Given the recent evidence that beta-catenin acts as a coactivator of AR, our findings suggest a novel mechanism by which PI3K/Akt modulates androgen signaling. In a PTEN-null prostate cancer cell line, we show that PTEN expression reduces beta-catenin-mediated augmentation of AR transactivation. Using the mutants of beta-catenin, we further demonstrate that the repressive effect of PTEN is mediated by a GSK3beta-regulated degradation of beta-catenin. Our results delineate a novel link among the PI3K, wnt, and androgen pathways and provide fresh insights into the mechanisms of prostate tumor development and progression.
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PMID:Phosphatidylinositol 3-kinase/Akt stimulates androgen pathway through GSK3beta inhibition and nuclear beta-catenin accumulation. 1206 52

Chromosomal deletion appears to be the earliest as well as the most frequent somatic genetic alteration during carcinogenesis. It inactivates a tumor suppressor gene in three ways, that is, revealing a gene mutation through loss of heterozygosity as proposed in the two-hit theory, inducing haploinsufficiency through quantitative hemizygous deletion and associated loss of expression, and truncating a genome by homozygous deletion. Whereas the two-hit theory has guided the isolation of many tumor suppressor genes, the haploinsufficiency hypothesis seems to be also useful in identifying target genes of chromosomal deletions, especially for the deletions detected by comparative genomic hybridization (CGH). At present, a number of chromosomal regions have been identified for their frequent deletions in prostate cancer, including 2q13-q33, 5q14-q23, 6q16-q22, 7q22-q32, 8p21-p22, 9p21-p22, 10q23-q24, 12p12-13, 13q14-q21, 16q22-24, and 18q21-q24. Strong candidate genes have been identified for some of these regions, including NKX3.1 from 8p21, PTEN from 10q23, p27/Kip1 from 12p13, and KLF5 from 13q21. In addition to their location in a region with frequent deletion, there are functional and/or genetic evidence supporting the candidacy of these genes. Thus far PTEN is the most frequently mutated gene in prostate cancer, and KLF5 showed the most frequent hemizygous deletion and loss of expression. A tumor suppressor role has been demonstrated for NKX3.1, PTEN, and p27/Kip1 in knockout mice models. Such genes are important targets of investigation for the development of biomarkers and therapeutic regimens.
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PMID:Chromosomal deletions and tumor suppressor genes in prostate cancer. 1208 61

Transformation and malignant progression of prostate cancer is regulated by the inability of prostatic epithelial cells to undergo apoptosis rather than by increased cell proliferation. The basic apoptotic machinery of most prostate cancer cells is intact and the inability to undergo apoptosis is due to molecular alterations that result in failure to initiate or execute apoptotic pathways. This review discusses the role of anti-apoptotic proteins such as Bcl-2/BclXL, NF-kappaB, IGF, caveolin, and Akt, and pro-apoptotic molecules such as PTEN, p53, Bin1, TGF-beta, and Par-4 that can regulate progression of prostate cancer. In addition to highlighting the salient features of these molecules and their relevance in apoptosis, this review provides an appraisal of their therapeutic potential in prostate cancer. Molecular targeting of these proteins and/or their innate pro- or anti-apoptotic pathways, either singly or in combination, may be explored in conjunction with conventional and currently available experimental strategies for the treatment of both hormone-sensitive and hormone-resistant prostate cancer.
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PMID:Regulation of apoptosis in prostate cancer. 1208 64

Prostate cancer presents with a broad spectrum of biologic behavior, ranging from being an indolent, incidental finding to an aggressively invasive and metastatic disease. An improved understanding of the events involved in prostate cancer progression is critically important to its diagnosis and staging, as well as to the development of new therapies. Tumor progression, particularly in aggressive and malignant tumors, is associated with the induction of an angiogenic, gene-driven switch. In prostate cancer, one of the most powerful stimulators of angiogenesis is the vascular endothelial growth factor (VEGF). VEGF transcription can be induced by hypoxia through activation of the PI3 kinase pathway and hypoxia-inducible factor alpha. MMAC/PTEN (henceforth referred to as PTEN) is a recently identified tumor suppressor gene residing on chromosome 10q23, which is frequently inactivated in a wide range of human tumors, including advanced prostate cancer. The goal of this study was to determine whether PTEN inhibits angiogenesis by modulating VEGF activity. Our results showed that reintroduction of the PTEN gene into human prostate PC-3 and LNCaP cells decreased VEGF secretion, which was accompanied by various biologic activities, including inhibited endothelial cell growth and migration. PTEN expression also down-regulated VEGF mRNA levels, as detected by RT-PCR analysis. Concomitant with lessened VEGF expression was the reduction of VEGF promoter activity in PTEN-expressing cells. Our findings suggest that PTEN modulates angiogenesis by regulating VEGF expression.
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PMID:MMAC/PTEN tumor suppressor gene regulates vascular endothelial growth factor-mediated angiogenesis in prostate cancer. 1216 88

Genetic alterations and/or deletion of the tumor suppressor gene PTEN/MMAC/TEP1 occur in many types of human cancer including prostate cancer. We describe the production of monoclonal antibody against recombinant human PTEN and the study of PTEN gene and protein expression in three commercially available human prostate cancer cell lines, PC-3, LNCaP, and DU 145. Northern blotting analyses showed that LNCaP and DU145 but not PC-3 cells expressed PTEN mRNA. However, Western blotting analyses using a monoclonal antibody against PTEN demonstrated the expression of PTEN protein in DU145 but not LNCaP cells. In DU 145 cells, PTEN expression at both the mRNA and protein levels inversely correlated with serum concentrations and levels of PKB/Akt phosphorylation. In addition, the basal activity of PKB/Akt as indicated by level of phosphorylation was higher in prostate cancer cells which do not express PTEN than that in the cells expressing wild type PTEN. Thus, PTEN may play a critical role in regulating cellular signaling in prostate cancer cells.
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PMID:Downregulation of PTEN/MMAC/TEP1 expression in human prostate cancer cell line DU145 by growth stimuli. 1219 Jan 24

A search for novel and biologically relevant androgen-regulated genes and processes in the human prostate led to the intriguing observation that androgens provoke a remarkable and coordinated increase in the expression of several genes involved in triglyceride and cholesterol synthesis in various prostatic adenocarcinoma cell lines. This coordinated activation was shown to be the result of a novel and indirect pathway in which androgens cause activation of a secondary transcription regulator, Sterol Regulatory Element Binding Protein (SREBP), a pivotal factor in the control of intracellular lipid homeostasis. The biological relevance of increased lipogenesis in the biology of prostate cancer is underlined by recent immunocytochemical investigations on needle biopsies showing an increase in the expression of Fatty Acid Synthase (FAS) in 94% of the tumor-lesions examined. This increase is already evident in the earliest recognizable lesions (Prostatic Intra-epithelial Neoplasia; PIN) and is more pronounced in tumors with a higher Gleason score, suggesting that increased FAS expression may serve both as an early tumor marker and as a marker of tumor progression. As in tumor cell-lines, increased FAS expression in prostate tumors seems to be only part of a more general and coordinated activation of lipogenic pathways. Further studies revealed that lipogenesis in prostate tumor cells can be enhanced not only by androgens but also by growth factors and by tumor-associated disturbances in signal transduction pathways. EGF, for instance, is also able to activate lipogenesis via the SREBP pathway and activation of the P13 kinase system by inactivation of PTEN (a phenomenon observed in some 50% of the prostate cancers) also causes increased lipogenesis. The early and nearly universal activation of lipogenesis in prostate cancers (and also in various other tumors) suggests that this may be a fundamental event in the development of the tumoral phenotype, an element that certainly merits further investigation. In addition, there are serious indications that interference with enhanced lipogenic activity in tumor cells may cause tumor cell death and delayed tumor development, suggesting that increased lipogenic activity in tumor cells may open a novel avenue for therapeutic intervention.
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PMID:[Androgens and increased lipogenesis in prostate cancer. Cell biologic and clinical perspectives]. 1223 42

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