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)

Increased expression of mac25/insulin-like growth factor binding-protein related protein-1 (IGFBP-rP1) in human breast and prostate epithelial cell lines results in the suppression of tumor growth. CDNA expression array analysis revealed increased manganese superoxide dismutase (SOD-2) expression in the mac25/IGFBP-rP1-transfected M12 human prostate cancer cell line compared to M12 control cells. SOD-2 has been postulated to be a tumor suppressor. SOD-2 was also increased in LNCaP cells stably transfected with mac25/IGFBP-rP1, but not in mac25/IGFBP-rP1-transfected PC-3 cells. Mac25 LNCaP cells had a marked decrease in tumor growth in nude mice compared to controls, but there was no difference in tumor growth in mac25 PC-3 cells compared to control. Phosphorylated Erk and Akt were increased in the M12 and LNCaP transfected mac25/IGFBP-rP1 cells but not PC-3 mac25. Inhibition of PI-3 kinase results in a marked decrease in viability of the M12-mac25 cells compared to M12 controls. Cells treated with H(2)O(2) result in an increase in phospho-ERK. Transfection of SOD-2 in M12 cells markedly decreased tumor growth, apoptosis, G1 delay in the cell cycle, and expression of senescence associated beta-galactosidase. These results suggest that one of the downstream mediators of the senescence-associated tumor suppression effect of mac25/IGFBP-rP1 is SOD-2.
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PMID:Increased manganese superoxide dismutase (SOD-2) is part of the mechanism for prostate tumor suppression by Mac25/insulin-like growth factor binding-protein-related protein-1. 1259 89

A loss of functional androgen receptor and an enhanced expression of growth factor receptors and associated ligands are causal genetic events in prostate cancer (PCA) progression. These genetic alterations lead to an epigenetic mechanism where a feedback autocrine loop between membrane receptor and ligand (e.g. EGFR-TGFalpha) results in a constitutive activation of MAPK-Elk1-AP1-mediated mitogenic signaling in human PCA at an advanced and androgen-independent stage. We rationalized that inhibiting these epigenetic events could be useful in controlling advanced PCA growth. Recently, we found that grape seed extract (GSE), a dietary supplement rich in flavonoid procyanidins, inhibits advanced and androgen-independent human PCA DU145 cell growth in culture and nude mice. Here, we performed detailed mechanistic studies to define the effect of GSE on EGFR-Shc-MAPK-Elk1-AP1-mediated mitogenic signaling in DU145 cells. Pretreatment of serum-starved cells with GSE resulted in 70% to almost complete inhibition of EGF-induced EGFR activation and 50% to complete inhibition of Shc activation, which corroborated with a comparable decrease in EGF-induced Shc binding to EGFR. Conversely, EGF-induced ERK1/2 phosphorylation was inhibited only by lower doses of GSE; in fact, higher doses showed an increase. Additional studies showed that GSE alone causes a dose- and time-dependent increase in ERK1/2 phosphorylation in starved DU145 cells that is inhibited by an MEK1 inhibitor PD98059. Independent of this increase in ERK1/2 phosphorylation, GSE showed a strong inhibition of ERK1/2 kinase activity to Elk1 in both cellular and cell-free systems. GSE treatment of cells also inhibited both EGF-induced and constitutively active Elk1 phosphorylation and AP1 activation. GSE treatment also showed DNA synthesis inhibition in starved and EGF-stimulated cells as well as loss of cell viability and apoptotic death that was further increased by adding MEK1 inhibitor. Since GSE strongly induced apoptosis independent of its affect on an increase in phospho-ERK1/2, we hypothesized that apoptotic effect of GSE could be by other mechanism(s) including its effect on stress-associated MAPK, the JNK. Indeed, GSE-treated cells showed a strong and sustained increase in phospho-JNK1/JNK2 levels, JNK activity and phospho-cJun levels. An inhibition of GSE-induced JNK activation by a novel JNK inhibitor SP600125 resulted in a significant reversal of GSE-induced apoptotic death suggesting the involvement of JNK activation by GSE in its apoptosis response. Together, these results suggest that anticancer effects of GSE in PCA be mediated via impairment of EGFR-ERK1/2-Elk1-AP1-mediated mitogenic signaling and activation of JNK causing growth inhibition and apoptosis, respectively.
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PMID:Grape seed extract inhibits EGF-induced and constitutively active mitogenic signaling but activates JNK in human prostate carcinoma DU145 cells: possible role in antiproliferation and apoptosis. 1261 55

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in several human tumors both in vitro and in vivo, however, some tumors remain resistant for poorly understood reasons. Using a quantitative DNA fragmentation assay for apoptosis, we have shown that human prostate cancer cells are resistant to a wide range of TRAIL doses up to 500 ng/ml. However, translation inhibitors, such as anisomycin, cycloheximide, emetine, harringtonine, and puromycin, unlike several transcription inhibitors, significantly sensitized PC3-neomycin (PC3-neo) cells to TRAIL-induced apoptosis. These effects were inhibited in PC3 cells engineered to express bcl2 (PC3-bcl2). Translation inhibitors led to activation of c-Jun N-terminal kinase (JNK), which plays a role in this sensitization process because inhibition of JNK activation resulted in protection against TRAIL plus translation inhibitor-induced apoptosis. JNK activation may be required for this process, but it is not sufficient because activation of JNK using an MEKK2 expression vector did not mimic the sensitizing effect of translation inhibitors. Other stress-activated protein kinases, such as ERK and p38, play an insignificant role in determining the apoptotic sensitivity. We conclude that activation of JNK is required for sensitization of PC3 cells to TRAIL-induced apoptosis by translation inhibitors in cells that are otherwise TRAIL-resistant. However, in addition to JNK activation, other aspects of translation inhibition such as the suppressed activity of apoptosis-inhibitory proteins or activation of other signal transduction pathways must also be involved.
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PMID:Translation inhibitors sensitize prostate cancer cells to apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) by activating c-Jun N-terminal kinase. 1266 65

Within the human prostate epithelium four cell populations can be discriminated based on their expression of keratins (K). Basal cells express high levels of K5 and K14, as well as p63, whereas they have very low levels of androgen receptor, prostate-specific antigen (PSA), K8, and K18. Luminal secretory cells lack p63, K5, and K14 but express high levels of K8, K18, androgen receptor, and PSA. Additionally, cells have been identified with a keratin phenotype intermediate between basal and luminal cells that co-express high levels of K5 and K18 (K5/18) as well as hepatocyte growth factor receptor c-MET. Although intermediate cells have been proposed as precursor cells of prostate cancer, their biology is ill defined. Epithelial cells in proliferative inflammatory atrophy (PIA) appear to be cycling rapidly as indicated by expression of Ki-67, and morphological transitions have been identified between PIA and high-grade prostate intraepithelial neoplasia. Many of the atrophic epithelial luminal cells in PIA are candidates for intermediate cells based in part on weak expression of PSA and androgen receptor, high levels of K8/18, and lack of p63. The objective of this study was to further clarify the phenotype of the proposed intermediate cells in PIA and to quantitatively determine the level in which these intermediate cells preferentially occur in PIA lesions. Intermediate cells were immunohistochemically demonstrated using antibodies to K5, K14, K18, and c-MET. Using radical prostatectomy specimens (n = 15) the area fraction of intermediate cells in normally differentiated prostate epithelium and PIA were quantified by a grid point counting method. Atrophic luminal cells of PIA lesions expressed K5 in 39.2 +/- 7.4% of cells compared to 2.4 +/- 2.3% in normal epithelium (P < 0.00001). By contrast, K14 was only expressed in 3.0 +/- 3.2% of the luminal cells. Previous studies have shown that virtually 100% of these atrophic luminal cells are strongly positive for K8/18. c-MET was present in 44.1 +/- 14.1% of luminal cells in PIA but only in 2.1 +/- 2.8% of luminal cells in normal epithelium (P < 0.00001). To unambiguously determine whether intermediate luminal cells in PIA show increased proliferative activity and decreased p27(kip1) expression, double-staining immunofluorescence of Ki-67 and K5, as well as p27(Kip1) and K5 was performed. Luminal cells in PIA often co-expressed K5 and Ki-67. Although p27(Kip1) was strongly expressed in K5-negative differentiated cells in normal epithelium, p27(Kip1) staining was absent in many of the K5-positive cells in the luminal compartment of PIA. We conclude that cells phenotypically intermediate between basal and secretory cells are enriched in PIA lesions. The finding of a large number of highly proliferating intermediate cells in PIA provides further support that these cells may serve as preferred target cells in prostate carcinogenesis.
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PMID:Intermediate cells in human prostate epithelium are enriched in proliferative inflammatory atrophy. 1270 36

H11, the eukaryotic homologue of a herpes simplex virus protein, has the crystallin motif of heat shock proteins (Hsp), but it differs from canonical family members in that mRNA and protein levels were reduced in various tumor tissues and cell lines (viz. melanoma, prostate cancer and sarcoma) relative to their normal counterparts. In these cells, expression was not restored by heat shock, but rather by the demethylating agent 5-aza-2'-deoxycytidine (Aza-C). Forced H11 expression by Aza-C treatment, transient transfection with H11 expression vectors, or retrovirus-mediated delivery of H11 under the control of a tetracycline-sensitive promoter triggered apoptosis. This is evidenced by a significant (p < 0.001) increase in the percentage of cells positive for terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) and for activation of caspase-3 and p38MAPK and by the co-localization of TUNEL+ nuclei with increased H11 levels. Apoptosis was partially inhibited by the pancaspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone or the p38MAPK inhibitor SB203580. It was abrogated by co-treatment with both inhibitors, suggesting that H11-triggered apoptosis is both caspase- and p38MAPK-dependent. A single site mutant (H11-W51C) had cytoprotective activity related to MEK/ERK activation, and it blocked H11-induced apoptosis in co-transfected and Aza-C-treated cells, indicating that it is a dominant negative mutant. This is the first report of a heat shock protein with proapoptotic activity.
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PMID:Forced expression of the H11 heat shock protein can be regulated by DNA methylation and trigger apoptosis in human cells. 1283 17

In recent decades, radiation research has concentrated primarily on the cancer cell compartment. Much less is known about the effect of ionizing radiation on the endothelial cell compartment and the complex interaction between tumor cells and their microenvironment. Here we report that ionizing radiation is a potent antiangiogenic agent that inhibits endothelial cell survival, proliferation, tube formation and invasion. Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor were able to reduce the radiosensitivity of endothelial cells. Yet, it is also found that radiation induces angiogenic factor production by tumor cells that can be abrogated by the addition of antiangiogenic agents. Receptor tyrosine kinase inhibitors of Flk-1/KDR/VEGFR2, FGFR1 and PDGFR beta, SU5416, and SU6668 enhanced the antiangiogenic effects of direct radiation of the endothelial cells. In a coculture system of PC3 prostate cancer cells and endothelial cells, isolated irradiation of the PC3 cells enhanced endothelial cell invasiveness through a Matrigel matrix, which was inhibited by SU5416 and SU6668. Furthermore, ionizing radiation up-regulated VEGF and basic fibroblast growth factor in PC3 cells and VEGFR2 in endothelial cells. Together these findings suggest a radiation-inducible protective role for tumor cells in the support of their associated vasculature that may be down-regulated by coadministration of angiogenesis inhibitors. These results rationalize concurrent administration of angiogenesis inhibitors and radiotherapy in cancer treatment.
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PMID:SU5416 and SU6668 attenuate the angiogenic effects of radiation-induced tumor cell growth factor production and amplify the direct anti-endothelial action of radiation in vitro. 1283 71

Bombesin and its mammalian homologue gastrin-releasing peptide have been shown to be highly expressed and secreted by neuroendocrine cells in prostate cancer, and are thought to be related to the carcinogenesis and progression of this disease. We found, in this study, bombesin specifically induced mitogen-activated protein (MAP) kinase activation as shown by increased extracellular regulated kinase (ERK) phosphorylation and epidermal growth factor (EGF) receptor transactivation in prostate cancer cells, which express functional gastrin-releasing peptide receptor. The transactivation of EGF receptor was required for bombesin-induced ERK phosphorylation. Furthermore, non-receptor tyrosine kinase Src and cellular Ca2+ were shown to be involved in bombesin-induced EGF receptor transactivation and ERK phosphorylation. Inhibition of either EGF receptor transactivation or ERK activation blocked bombesin-induced DNA synthesis in these cells. Taken together, these data suggest bombesin may act as a mitogen in prostate cancer by activating MAP kinase pathway via EGFR transactivation.
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PMID:Activation of extracellular signal-regulated kinase mediates bombesin-induced mitogenic responses in prostate cancer cells. 1287 8

We have previously demonstrated the differential expression in tumor-associated blood vessels of two vascular endothelial growth factor receptors (VEGFRs), VEGFR1 and VEGFR2, during initiation and progression of prostate cancer in the genetically engineered transgenic adenocarcinoma of the mouse prostate (TRAMP) mouse model. In our "progression switch" model, expression of VEGFR1 is associated with early and more differentiated disease, whereas expression of VEGFR2 is associated with advanced and more poorly differentiated disease. To test the hypothesis that stage-specific inhibition of vascular endothelial growth factor signaling could be used as therapy for autochthonous prostate cancer, we initiated a preclinical trial with SU5416, a potent antiangiogenic small molecule inhibitor of VEGFR associated tyrosine kinase activity. In our early intervention trial, administration of SU5416 to TRAMP mice did not appear to influence angiogenesis or tumor progression between 10 and 16 weeks of age, a time corresponding to high levels of VEGFR1 expression. In our late intervention trial, however, we observed a significant decrease in tumor-associated mean vessel density, increased apoptotic index, and pronounced regions of cell death when SU5416 was administered to TRAMP mice between 16 and 22 weeks of age, a time corresponding to high levels of VEGFR2 expression. These results clearly demonstrate that therapy directed specifically against the VEGFR signaling axis can dramatically impair angiogenesis and induce apoptosis of autochthonous spontaneous and progressive prostate cancer.
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PMID:SU5416 selectively impairs angiogenesis to induce prostate cancer-specific apoptosis. 1288 33

Because ErbB-2 receptor is involved in hormone-independency for growth and metastasis of prostate cancer cells, the aim was to investigate the effects of quercetin on ErbB-2 and ErbB-3 expression and its critical components such as MAP kinase and PI-3 kinase. Hemocytometric counts and [3H]-thymidine incorporation were used to determine the effects of quercetin, EGF and TGF-alpha on cell proliferation and DNA synthesis in PC-3 and LnCap cells. Changes in ErbB-2, ErbB-3 and components of MAPK and PI-3K pathways were analyzed by Western blot analysis. Treatment of PC-3 and LnCap cells with quercetin resulted in a dose-dependent growth inhibition. The rate of DNA synthesis was decreased by 40, 55 and 65% on treatment with 14.5, 29.0 and 58.0 microM of quercetin, respectively. Concomitantly, these treatments led to a dose-dependent decrease in ErbB-2, ErbB-3 and their basal autophosphorylation levels as compared to controls. Cyclin D1 expression and basal phosphorylation of c-Raf, MAPK, Elk-1 and Akt-1 in PC-3 cells was also inhibited by quercetin treatment. Co-treating PC-3 cells with quercetin significantly attenuated EGF- and TGF-alpha-induced growth and phosphorylation of ErbB-2, ErbB-3, c-Raf, MAPK kinase 1/2 (MEK1/2), MAPK, Elk-1 and Akt-1. Since ErbB receptor is important for growth, metastasis and drug resistance, inhibition of ErbB-2 and ErbB-3 by pharmacological doses of quercetin may provide a new approach for treatment of prostate cancers.
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PMID:Inhibition of ErbB-2 and ErbB-3 expression by quercetin prevents transforming growth factor alpha (TGF-alpha)- and epidermal growth factor (EGF)-induced human PC-3 prostate cancer cell proliferation. 1288 23

BACKGROUND: Steroid hormone receptors (SHRs) are members of the superfamily of ligand-activated transcription factors that regulate many biological processes. Co-regulators act as bridging molecules between the SHR and general transcription factors to enhance transactivation of target genes. Previous studies demonstrated that Stat3 is constitutively activated in prostate cancer and can enhance prostate specific antigen (PSA) expression and promote androgen independent growth. In this study, we investigate whether Stat3 can enhance steroid hormone receptors activation. METHODS: CV-1 cells in which plasmids expressing androgen receptor (AR), glucocorticoid receptor (GR), progesterone receptor (PR) or estrogen receptor (ER) were cotransfected with a constitutively active STAT3 mutant. RESULTS: Stat3 stimulates the transcriptional activity of all four SHR tested, AR, GR, PR and ER, in a hormone-dependent manner. Stat3 acts in a synergistic fashion with other coactivators such as SRC-1, pCAF, CBP, and TIF-2 on the transcriptional activity of these SHR. In addition, Stat3 significantly enhanced the sensitivity of androgen receptor in response to androgen. STAT3 did not affect the specificity of AR for other steroid hormones other than androgen or binding of AR to other hormone responsive elements. CONCLUSIONS: These findings suggest that Stat3 can enhance the transactivation of AR, GR, PR and ER, and activated Stat3 could have a role in the development or progression of a hypersensitive AR.
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PMID:Stat3 enhances transactivation of steroid hormone receptors. 1290 56


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