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)

In the present study, we demonstrate that Rosiglitazone (Rosi), a thiazolidinedione and PPARgamma agonist, induces ERE (Estrogen Receptor Response Element) reporter activity, pS2 (an endogenous ER gene target) expression, and proliferation of ER positive breast cancer (MCF-7) cells. By performing a dose-response assay, we determined that high concentrations of Rosi inhibit proliferation, while low concentrations of Rosi induce proliferation. Using the anti-estrogen ICI, ER negative breast cancer (MDA-MB-231) cells, and a prostate cancer cell line (22Rv1) deficient in both ERalpha and PPARgamma, we determined that Rosiglitazone-induced ERE reporter activation and proliferation is through an ERalpha dependent mechanism. Rosiglitazone-induced ERE activation is also dependent on activation of the Extracellular Signal-Regulated Kinase-Mitogen Activated Protein Kinase (ERK-MAPK) pathway, since it is inhibited by co-treatment with U0126, a specific inhibitor of this pathway. We also demonstrate that when ERalpha and PPARgamma are both present, they compete for Rosi, inhibiting each others transactivation. To begin to unravel the pharmacological mechanism of Rosi-induced ER activation, sub-maximally effective concentrations of E(2) were used in combination with increasing concentrations of Rosi in luciferase reporter assays. From these assays it appears that E(2) and Rosi both activate ERalpha via similar pharmacological mechanisms. Furthermore sub-maximally effective concentrations of E(2) and Rosi additively increase both ERE reporter activity and MCF-7 cell proliferation. The results of this study may have clinical relevancy for Rosi's use both as an anti-diabetic in post-menopausal women and as an anti-cancer drug in women with ER positive breast cancer.
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PMID:Transactivation of ERalpha by Rosiglitazone induces proliferation in breast cancer cells. 1745 34

Peroxisome proliferator-activated receptor gamma (PPARgamma) ligands seem to induce anticancer effects on prostate cancer cells, but the mechanism is not clear. The effect of PPARgamma ligands omega-6 fatty acids and ciglitazone (2-15 microM)--on proliferation, and apoptosis of LNCaP, PC-3, DU145, CA-K and BPH-K cells was studied. PPARgamma ligands led to: (1) reduction of proliferation (20-50%) of all the studied cell lines, (2) stimulation of differentiation of prostate cancer cells through an increased expression (1.5-3-fold: LNCaP, DU145, BPH-K) or reexpression (PC-3, CA-K) of E-cadherin with parallel inhibition of N-cadherin expression (PC-3, CA-K) and (3) down-regulation (1-2-fold) of beta-catenin and c-myc expression. The selective PPARgamma antagonist GW9662 abolished the effect of those ligands on prostate cancer cells. These results suggest that inhibition of beta-catenin and in effect c-myc expression through activation of PPARgamma may help prostate cancer cells to restore several characteristics of normal prostate cells phenotype.
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PMID:Does the inhibition of c-myc expression mediate the anti-tumor activity of PPAR's ligands in prostate cancer cell lines? 1746 58

Human PCAN1 (prostate cancer gene 1) is a prostate-specific gene that is highly expressed in prostate epithelial tissue, and frequently mutated in prostate tumors. To better understand the regulation of the PCAN1 gene, a 2.6-kb fragment of its 5' flanking region was obtained by PCR. Its promoter activity was examined via the dual-luciferase reporter assay after it had been cloned into a pGL(3)-basic vector generating pGL(3)-p2.6 kb and transfected into LNCaP cells. pGL(3)-basic and pGL(3)-control were respectively used as the negative and positive controls. Sequence analysis with the MatInspector database showed that some possible binding sites for the transcriptional factors, NKX3.1, P53, SP1, cEBP and the PPAR/RXR heterodimers may locate on a 2.6-kb region upstream of the PCAN1 gene. To examine the relevant regulation of PCAN1, pGL(3)-p2.6 kb was transfected into the prostate cancer cell line LNCaP, which was treated with R1881 (10(-7) approximately 10(-9) mol/l), 17beta-estradiol (17beta-E(2), 10(-7) approximately 10(-9) mol/l), all-trans-retinoic acid (all-trans-RA, 10(-5) approximately 10(-7) mol/l) or 9-cis-retinoic acid (9-cis-RA, 10(-5) approximately 10(-7) mol/l), and eukaryotic expression plasmids of NKX3.1, p53, Sp1, Pten, PPARgamma or cEBPalpha were cotransfected with pGL(3)-p2.6 kb into LNCaP cells. pRL-TK, a Renilla luciferase reporter vector, was cotransfected into all the transfection lines as an internal control. The activities of pGL(3)-p2.6 kb (PCAN1 promoter) were analyzed via the dual-luciferase reporter assay 48 h after transfection. The results showed that 9-cis-RA enhanced the PCAN1 promoter activity in a dose-dependent manner, while R1881, 17beta-E(2) and all-trans-RA had no significant effect on PCAN1 promoter activities. Cotransfection with pGL(3)-p2.6kb and the expression plasmids of NKX3.1, p53, Sp1 or Pten respectively resulted in 1.66-, 2.48-, 2.00-and 1.72-fold 2.6 kb PCAN1 promoter activity increases relative to the controls, which were cotransfected with pcDNA3.1(+), while cotransfection of PPARgamma and cEBPalpha yielded no significant effect on PCAN1 promoter activities. These results could be applied for further study of the function and transcription regulation of the PCAN1 gene in prostate development and carcinogenesis.
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PMID:Molecular cloning and analysis of the human PCAN1 (GDEP) promoter. 1746 39

Considering the role of aberrant beta-catenin signaling in tumorigenesis, we investigated the mechanism by which the peroxisome proliferator-activated receptor gamma (PPARgamma) agonist troglitazone facilitated beta-catenin down-regulation. We demonstrate that troglitazone and its more potent PPARgamma-inactive analogs Delta2TG and STG28 mediated the proteasomal degradation of beta-catenin in prostate cancer cells by up-regulating the expression of beta-transducin repeat-containing protein (beta-TrCP), an F-box component of the Skp1-Cul1-F-box protein E3 ubiquitin ligase. Evidence indicates that although small interfering RNA-mediated beta-TrCP knockdown protected cells against STG28-facilitated beta-catenin ablation, ectopic beta-TrCP expression enhanced the degradation. The involvement of beta-TrCP in beta-catenin degradation was also corroborated by the pull-down analysis and the concurrent down-regulation of known beta-TrCP substrates examined, including Wee1, Ikappabetaalpha, cdc25A, and nuclear factor-kappaB/p105. Furthermore, glycogen synthase kinase-3beta represented a key regulator in the effect of these thiazolidinedione derivatives on beta-catenin proteolysis even though these agents increased its phosphorylation level. It is noteworthy that this drug-induced beta-TrCP up-regulation was accompanied by the concomitant down-regulation of Skp2 and Fbw7, thereby affecting many of the target proteins of these two F-box proteins (such as p27 and cyclin E). As a consequence, the ability of troglitazone to target these F-box proteins provides a molecular basis to account for its reported effect on modulating the expression of aforementioned cell-cycle regulatory proteins. Despite this complicated mode of pharmacological actions, normal prostate epithelial cells, relative to LNCaP cells, were less susceptible to the effects of STG28 on modulating the expression of beta-catenin and beta-TrCP, suggesting the translation potential of using STG28 as a scaffold to develop more potent chemopreventive agents.
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PMID:Thiazolidinediones modulate the expression of beta-catenin and other cell-cycle regulatory proteins by targeting the F-box proteins of Skp1-Cul1-F-box protein E3 ubiquitin ligase independently of peroxisome proliferator-activated receptor gamma. 1756 95

Methyl 2-cyano-3,11-dioxo-18beta-olean-1,12-diene-30-oate (beta-CDODA-Me) is a synthetic analog of the naturally occurring triterpenoid glycyrrhetinic acid, which contains a 2-cyano substituent in the A-ring. beta-CDODA-Me was a potent inhibitor of LNCaP prostate cancer cell growth (IC(50) approximately 1 muM) and activated peroxisome proliferator-activated receptor gamma (PPARgamma), whereas analogs without the cyano group were weakly cytotoxic and did not activate PPARgamma. beta-CDODA-Me induced p21 and p27, down-regulated cyclin D1 protein expression, and induced two other proapoptotic proteins, namely nonsteroidal anti-inflammatory drug-activated gene-1 and activating transcription factor-3. However, induction of these responses by beta-CDODA-Me was PPARgamma-independent and due to activation of phosphatidylinositol-3-kinase, mitogen-activated protein kinase, and jun N-terminal kinase pathways by this compound. In contrast, beta-CDODA-Me also decreased androgen receptor (AR) and prostate-specific antigen (PSA) mRNA and protein levels through kinase-independent pathways. beta-CDODA-Me repressed AR mRNA transcription, whereas decreased PSA mRNA levels were dependent on protein synthesis and were reversed by cycloheximide. Thus, potent inhibition of LNCaP cell survival by beta-CDODA-Me is due to PPARgamma-independent activation of multiple pathways that selectively activate growth-inhibitory and proapoptotic responses.
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PMID:Methyl 2-cyano-3,11-dioxo-18 beta-olean-1,12-dien-30-oate is a peroxisome proliferator-activated receptor-gamma agonist that induces receptor-independent apoptosis in LNCaP prostate cancer cells. 1798 48

BAG-1 is a pleiotropic protein that exists as multiple isoforms. BAG-1 overexpression in breast cancer is associated with outcome. BAG-1 modulates the function of various nuclear hormone receptors, including the oestrogen receptor, and BAG-1 can influence the in vitro action of anti-hormonal therapies such as cyproterone acetate in prostate cancer. Activation of PPARgamma, a nuclear hormone receptor important for lipid and glucose homeostasis, may present a new therapeutic approach for breast cancer, since PPARgamma agonists promote cell cycle arrest, differentiation and apoptosis in breast cancer cells. Here we determined whether BAG-1 also modulated PPARgamma function in MCF7 cells. 15-deoxy-Delta12, 14-prostaglandin J(2) (15dPGJ2), an agonistic ligand for PPARgamma, induced expression of HSP70, a BAG-1 binding partner, but did not alter BAG-1 isoform expression. Overexpression of BAG-1 isoforms did not alter PPARgamma-dependent transcription or interfere with 15dPGJ2-induced cell cycle arrest or differentiation. However, overexpression of BAG-1 isoforms did interfere with induction of cell death by 15dPGJ2. Thus, BAG-1 is unlikely to directly modulate PPARgamma function, but the overexpression of BAG-1 in some breast cancers may limit the efficacy of PPARgamma agonists as cancer therapies, by suppression of PPARgamma-induced cell death pathways.
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PMID:BAG-1 inhibits PPARgamma-induced cell death, but not PPARgamma-induced transcription, cell cycle arrest or differentiation in breast cancer cells. 1828 3

Peroxisome proliferator-activated receptor-gamma (PPAR)-gamma is a ligand-activated transcriptional factor belonging to steroid receptor superfamily. PPAR-gamma plays a role in both adipocyte differentiation and tumorigenesis. Up to date, PPAR-gamma is expressed in various cancer tissues, and PPAR-gamma ligand induces growth arrest of these cancer cells. In this study, we examined the expression of PPAR-gamma in prostate cancer (PC) and testicular cancer (TC) by RT-PCR and immunohistochemistry, and we also examined the effect of PPAR-gamma ligand in these cells by MTT assay, hoechest staining, and flow cytometry. PPAR-gamma expression was significantly more extensive and intense in malignant tissues than in normal tissues. PPAR-gamma ligand induced the reduction of malignant cell viability through apoptosis. These results demonstrated that the generated PPAR-gamma in PC and TC cells might play an important role in the tumorigenesis. PPAR-gamma may become a new target in the treatment of PC and TC.
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PMID:Peroxisome Proliferator-Activated Receptor-gamma Is a Potent Target for Prevention and Treatment in Human Prostate and Testicular Cancer. 1831 13

Syndecan 1 is the major proteoglycan produced by epithelial cells. It is strategically localized at the plasma membrane to participate in growth factor signaling and cell-cell and cell-matrix interactions. Its expression may modulate the properties of epithelial lineage tumor cells in which it is generally down-regulated compared with nontumor progenitors. The present study examined the regulation of syndecan 1 in prostate epithelial cells by n-3 polyunsaturated fatty acids. In prostate tissue of mice, syndecan 1 immunostaining was demonstrated in epithelial cells throughout each gland. In animals fed an n-3 polyunsaturated fatty acid-enriched diet, syndecan 1 mRNA was increased in all prostate glands. In the human prostate cancer cell line, PC-3, delivery of exogenous n-3 (but not n-6) fatty acids resulted in up-regulation of syndecan 1 expression. This effect was mimicked by a peroxisome proliferator-activated receptor (PPAR) gamma agonist, troglitazone, and inhibited in the presence of a PPARgamma antagonist and in cells transfected with dominant negative PPARgamma cDNA. Using a luciferase gene driven either by a PPAR response element or by a DR-1 site present in the syndecan 1 promoter, reporter activation was increased by n-3 low density lipoprotein, docosahexaenoic acid, and troglitazone, whereas activity of a luciferase gene placed downstream of a mutant DR-1 site was unresponsive. These findings indicate that syndecan 1 is up-regulated by n-3 fatty acids by a transcriptional pathway involving PPARgamma. This mechanism may contribute to the chemopreventive properties of n-3 fatty acids in prostate cancer.
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PMID:In vivo and in vitro regulation of syndecan 1 in prostate cells by n-3 polyunsaturated fatty acids. 1845 Jul 55

PPARgamma, a member of the peroxisome proliferator-activated receptor family, is overexpressed in prostate cancer. Natural and synthetic ligands of PPARgamma via genomic and nongenomic actions promote cell cycle arrest and apoptosis of several prostate cancer cells, in vitro. Insulin-like growth factor 1 (IGF-1) inhibits the adriamycin-induced apoptosis of PC-3 human prostate cancer cells. Therefore, we have analyzed the ability of two PPARgamma ligands,15dPGJ2 and rosiglitazone, a natural and a synthetic PPARgamma ligand, respectively, to increase the adriamycin-induced cytotoxicity of PC-3 cells and to suppress the IGF-1 survival effect on adriamycin-induced apoptosis of PC-3 cells. Our data revealed that both the PPARgamma ligands increased the adriamycin-induced cytostasis of PC-3 cells, however, only rosiglitazone added to the adriamycin-induced apoptosis of PC-3 cells. In addition, rosiglitazone attenuated the type I IGF receptor (IGF-1R) survival signaling on adriamycin-induced apoptosis of PC-3 cells via its nongenomic action on ERK1/2 and AKT phosphorylation. Because the IGF-1R signaling is probably the most important host tissue (bone) metastasis microenvironment-related survival signaling for prostate cancer cells, we conclude that rosiglitazone effects on IGF-1R-mediated activation of ERK1/2 and AKT could have clinical implications for the management of androgen ablation-refractory and chemotherapy-resistant advanced prostate cancer with bone metastasis.
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PMID:Rosiglitazone attenuates insulin-like growth factor 1 receptor survival signaling in PC-3 cells. 1847 8

We cloned a novel splicing variant for nuclear coactivator p120(alpha), designated as p120beta and studied its function and expression in several human prostate diseases. Transfection assays demonstrated that p120beta functions as a strong coactivator for androgen receptor (AR), but weakly for other nuclear receptors. GST-pull down assay showed that a glutamine-rich region of the p120 bound to the ligand-binding domain of AR. Interestingly, p120beta mRNAs were expressed predominantly in the normal prostate, androgen-responsive prostate cancers and an androgen-sensitive prostate cancer cell line, LNCaP, but weakly in recurrent cancers and the androgen-insensitive prostate cancer cell lines PC3 and DU145. Furthermore, knockdown of p120alpha by siRNA abolished coactivator activity on thyroid hormone receptors (TR) and PPARgamma, but did not affect that of ARs in PC3 cells. In addition, competitive assay with other nuclear receptors demonstrated that TR and PPARgamma did not inhibit p120beta-induced stimulation. These findings suggested that while p120alpha was essential for ligand-dependent stimulation of TRs and PPARgamma, p120beta acted as a coactivating protein predominantly for AR.
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PMID:A novel splice variant of the nuclear coactivator p120 functions strongly for androgen receptor: characteristic expression in prostate disease. 1856 Feb 2


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