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)

Epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) are potent mitogens that regulate proliferation of prostate cancer cells via autocrine and paracrine loops and promote tumor metastasis. They exert their action through binding to the corresponding cell surface receptors that initiate an intracellular phosphorylation cascade, leading to the activation of mitogen-activated protein kinases (MAPKs), which recruit transcription factors. We have studied the effects of EGF, IGF-I, and the protein kinase A (PKA) activator forskolin on the activation of p42/ extracellular signal-regulated kinase (ERK)2, which is a key kinase in mediation of growth factor-induced mitogenesis in prostate cancer cells. The activity of p42/ERK2 was determined by immune complex kinase assays and by immunoblotting using a phospho p44/p42 MAPK-specific antibody. EGF, IGF-I, and forskolin-induced PKA activity stimulate intracellular signaling pathways converging at the level of p42/ERK2. In the androgen-insensitive DU145 cell line, there is a constitutive basal p42/ ERK2 activity that is not present in androgen-sensitive LNCaP cells. Constitutive p42/ERK2 activity is abrogated by blockade of the EGF receptor. Hence, it is obviously caused by an autocrine loop involving this receptor. The effects of EGF on p42/ERK2 are potentiated by forskolin in both cell lines. The blockade of PKA by the specific inhibitor H89 attenuates this synergism. This finding is in contrast to those obtained in several other systems studied thus far, in which PKA activators inhibited MAPKs. p42/ERK2 in DU145 cells is highly responsive to IGF-I stimulation, whereas no effect of IGF-I on p42/ERK2 can be measured in LNCaP cells. Moreover, our results demonstrate that selective blockade of the EGF receptor in prostate cancer cells does not only inhibit the action of EGF, but also IGF-I-induced activation of the MAPK pathway and the interaction with the PKA pathway. In conclusion, these findings offer new possibilities for a therapeutical intervention in prostate cancer by targeting signaling pathways of growth factors and PKA.
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PMID:Epidermal growth factor (EGF) receptor blockade inhibits the action of EGF, insulin-like growth factor I, and a protein kinase A activator on the mitogen-activated protein kinase pathway in prostate cancer cell lines. 989 11

Intracellular signaling pathways that mediate survival of prostate carcinoma (PCa) cells are poorly understood. We examined the potential role of the phosphatidylinositol 3' kinase (PI3K) pathway as a mediator of cell survival in LNCaP human PCa cells, which express a variety of properties characteristic of human prostate cancer. LNCaP cell cultures rapidly became apoptotic when treated with the specific PI3K inhibitors, wortmannin and LY294002. In contrast, apoptosis was not induced when the cells were treated with: (a) rapamycin, an inhibitor of the ribosomal S6 kinase pp70S6K, which acts downstream of PI3K; (b) PD98059, a specific inhibitor of the extracellular signal-regulated kinase/mitogen-activated protein kinase (Erk/MAPK) kinase (MEK); or (c) the antiandrogen, Casodex; or when the cells were cultured under androgen-depleted conditions. Apoptosis induced by PI3K inhibition was attenuated by: (a) dihydrotestosterone; or (b) the ErbB1 activating ligands [epidermal growth factor (EGF), transforming growth factor alpha, or heparin-binding EGF-like growth factor]. In response to ErbB1 activation by ligand, the p85 regulatory subunit of PI3K associated specifically with ErbB3 but not detectably with ErbB1. The anti-apoptotic effect of ErbB1 activation was significantly reduced when cells were treated simultaneously with wortmannin and PD98059. These data indicate that survival signals can be evoked in LNCaP cells by several distinct pathways and can be triggered by nuclear and cell-surface receptors. Constitutive signaling through the PI3K pathway is required to prevent cell death in LNCaP, whereas activation of the Erk/MAPK and androgen response pathways is not obligatory for cell survival. These results also show that survival signals, as distinguished from mitogenic signals, can be evoked in PCa cells by ErbB1 ligands known to be synthesized within the human prostate.
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PMID:The phosphatidylinositol 3'-kinase pathway is a dominant growth factor-activated cell survival pathway in LNCaP human prostate carcinoma cells. 1038 51

We investigated the potential of genistein, the primary isoflavone of soy, to protect against breast and prostate cancers in animal models. For mammary cancer studies, Sprague-Dawley rats were fed AIN-76A diet plus minus 250 mg genistein/kg diet. Dimethylbenz[a]anthracene was administered by gavage at d 50 postpartum to induce mammary tumors. Mammary cancer chemoprevention was demonstrated after prepubertal and combined prepubertal and adult genistein treatments but not after prenatal- or adult-only treatments, demonstrating that the timing of exposure to genistein is important for mammary cancer chemoprevention. The cellular mechanism of action was found to be mammary gland and cell differentiation, as shown by whole-mount analysis and beta-casein expression. An imprinting effect was shown for epidermal growth factor receptor expression in mammary terminal end buds. For prostate cancer studies, we used two models. The first was a chemically (N-methylnitrosourea) induced prostate cancer rat model. Genistein in the diet inhibited the development of invasive adenocarcinomas in a dose-dependent manner. The second model was a transgenic mouse model that resulted in spontaneously developing adenocarcinoma tumor of the prostate. Genistein in the diet reduced the incidence of poorly differentiated prostatic adenocarcinomas in a dose-dependent manner and down-regulated androgen receptor, estrogen receptor-alpha, progesterone receptor, epidermal growth factor receptor, insulin-like growth factor-I, and extracellular signal-regulated kinase-1 but not estrogen receptor-beta and transforming growth factor-alpha mRNA expressions. We conclude that dietary genistein protects against mammary and prostate cancers by regulating specific sex steroid receptors and growth factor signaling pathways.
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PMID:Genistein chemoprevention: timing and mechanisms of action in murine mammary and prostate. 1188 May 92

Prostatic epithelial cells that are capable of surviving in the absence of androgenic steroids were found to express protein kinase Cepsilon (PKCepsilon), an oncogenic protein capable of promoting autocrine cell-signaling events. Gene transfer experiments demonstrated that PKCepsilon overexpression was sufficient to transform androgen-dependent LNCaP cells into an androgen-independent variant that rapidly initiated tumor growth in vivo in both intact and castrated male nude mice. This transformation was associated with an accelerated rate of androgen-independent LNCaP cell proliferation, resistance to apoptosis, hyperphosphorylation of the mitogen-activated protein kinase extracellular signal-regulated kinase and transcriptional repressor protein retinoblastoma, and increased expression of E2F-1 and other 5'-cap-dependent mRNAs, including the G(1) cyclins, c-myc, and caveolin-1. Coimmunoprecipitation experiments indicated that PKCepsilon was associated with members of the extracellular signal-regulated kinase signaling cascade and the scaffolding protein caveolin-1. Caveolin-1, produced by LNCaP cells overexpressing PKCepsilon, was released into the medium, possibly through a Golgi-independent route, and significant growth inhibition was observed when these cells were cultured in the presence of an anti-caveolin-1 antiserum. Finally, antisense experiments established that endogenous PKCepsilon plays an important role in regulating the growth and survival of androgen-independent prostate cancer cells. This study provides several independent lines of evidence supporting the hypothesis that PKCepsilon expression may be sufficient to maintain prostate cancer growth and survival after androgen ablation.
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PMID:Protein kinase cepsilon has the potential to advance the recurrence of human prostate cancer. 1195 6

The lipid growth factor lysophosphatidic acid (LPA) elicits multiple cellular responses, including cell growth and survival. LPA acts upon target cells by activating its cognate receptors, which belong to the G protein-coupled endothelial differentiation gene (EDG) family. To date, three known LPA receptors, termed LPA1, LPA2 and LPA3, have been molecularly characterized and cloned. Here, we review recent data describing the molecular steps involved in the LPA receptor-mediated activation of mitogenic extracellular signal-regulated kinase (ERK) pathway in prostate cancer. Induction of ERK by LPA proceeds via Gbetagamma-dependent activation of tyrosine kinases, including the epidermal growth factor (EGF) receptor and c-Src. Further, LPA-induced ERK activation involves matrix metalloproteinases (MMPs), which cause the release of active EGFR ligands. Finally, we present data demonstrating a correlation between the mitogenic effects of LPA and expression of the lp(A1) gene in the prostate cancer cells.
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PMID:Mitogenic action of LPA in prostate. 1206 37

Lysophosphatidic acid (LPA) is a lipid mediator that may play an important role in growth and survival of carcinomas. In this study, LPA production and response were characterized in two human prostate cancer (CaP) cell lines: PC-3 and Du145. Bombesin, a neuroendocrine peptide that is mitogenic for CaP cells, stimulated focal adhesion kinase phosphorylation and activated the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway. Similar responses were elicited by 18:1 LPA (oleoyl-LPA). Studies using radioisotopic labeling revealed that both PC-3 and Du145 generate LPA and that LPA production is increased by bombesin. The kinetics of bombesin-induced phospholipase D activation and LPA production were similar. Using electrospray ionization mass spectrometry, 18:1 LPA was found to be an abundant LPA species in CaP cell medium. Structure activity studies of acyl-LPAs revealed that 18:1 LPA is most efficacious for activation of extracellular signal-regulated kinase and phospholipase D in CaP cells. Incubation with 18:1 LPA caused homologous desensitization of LPA response, whereas bombesin caused heterologous desensitization. LPA was present at nanomolar levels in medium from bombesin-treated cells. LPA extracted from the medium induced calcium mobilization in CaP cells. These results demonstrate that bioactive LPA is generated by CaP cells in response to a mitogen and suggest that 18:1 LPA can act as an autocrine mediator.
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PMID:Role for 18:1 lysophosphatidic acid as an autocrine mediator in prostate cancer cells. 1208 19

Experiments with human prostate cancer cell lines have shown that forced overexpression of the ErbB2-receptor tyrosine kinase (RTK) promotes androgen-independent growth and increases androgen receptor-transcriptional activity in a ligand-independent fashion. To investigate the relationship between ErbB-RTK signaling and androgen in genetically unmanipulated human prostate cancer, we performed biochemical and biological studies with the dual ErbB1/ErbB2 RTK inhibitor PKI-166 using human prostate cancer xenograft models with isogenic sublines reflecting the transition from androgen-dependent to androgen-independent growth. In the presence of low androgen concentrations, PKI-166 showed profound growth-inhibitory effects on tumor growth, which could be partially reversed by androgen add-back. At physiological androgen concentrations, androgen withdrawal greatly enhanced the ability of PKI-166 to retard tumor growth. The level of extracellular signal-regulated kinase activation correlated with the response to PKI-166 treatment, whereas the expression levels of ErbB1 and ErbB2 did not. These results suggest that ErbB1/ErbB2 RTKs play an important role in the biology of androgen-independent prostate cancer and provide a rationale for clinical evaluation of inhibitors targeted to this pathway.
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PMID:Growth inhibitory effects of the dual ErbB1/ErbB2 tyrosine kinase inhibitor PKI-166 on human prostate cancer xenografts. 1223 93

The synthetic retinoid N-(4-hydroxyphenyl)retinamide (4-HPR) has been shown to induce apoptosis in various types of tumors, including prostate cancer. We sought to examine the key mechanisms affecting the resistance to 4-HPR-induced apoptosis in three human prostate cancer cell lines, PC-3, DU145, and LNCaP. Concentrations of more than 40 microM 4-HPR produced apoptosis to almost the same extent in all cell lines; however, only the LNCaP line remained highly sensitive to concentrations less than 10 microM. These differing sensitivities at low concentrations correlated well with the level of constitutive activation of nuclear factor kappa B (NFkappaB) in the individual cell lines. We found that NFkappaB activation inhibited c-jun NH(2)-terminal kinase and caspase 3 activation induced by 4-HPR and that NFkappaB inhibition by the I kappa B alpha phosphorylation inhibitor compound Bay 117082 resulted in increasing sensitization of both PC-3 and DU145 lines to apoptosis induced by 4-HPR at low concentrations. Furthermore, we found that inhibition of extracellular signal-regulated kinase (ERK) enhanced the suppression of NFkappaB by 4-HPR and also resulted in sensitization to apoptosis in the DU145 cell line, in which ERK is activated constitutively. It thus appears that mitogen-activated protein kinase associated with the activity of NFkappaB plays an important role in the degree of resistance to 4-HPR-induced apoptosis in human prostate cancer cells.
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PMID:Contributions of mitogen-activated protein kinase and nuclear factor kappa B to N-(4-hydroxyphenyl)retinamide-induced apoptosis in prostate cancer cells. 1241 May 64

Selenium has been implicated as a promising chemopreventive agent for prostate cancer. Whereas the anticancer mechanisms have not been clearly defined, one hypothesis relates to selenium metabolites, especially the monomethyl selenium pool, generated under supranutritional selenium supplementation. To explore potential molecular targets for mediating the chemopreventive activity, we contrasted the effects of methylseleninic acid (MSeA), a novel precursor of methylselenol, versus sodium selenite, a representative of the hydrogen selenide metabolite pool, on apoptosis execution, cell cycle distribution, and selected protein kinases in DU145 human prostate cancer cells. Exposure of DU145 cells to 3 microM MSeA led to a profound G1 arrest at 24 h, and exposure to greater concentrations led to not only G1 arrest, but also to DNA fragmentation and caspase-mediated cleavage of poly(ADP-ribose) polymerase (PARP), two biochemical hallmarks of apoptosis. Immunobiot analyses indicated that G1 arrest induced by the subapoptogenic doses of MSeA was associated with increased expression of p27kip1 and p21cip1, but apoptosis was accompanied by dose-dependent decreases of phosphorylation of protein kinase AKT and extracellular signal-regulated kinase (ERK1/2) in the absence of any phosphorylation change in p38 mitogen-activated protein kinase (p38MAPK) and c-Jun NH2-terminal kinase (JNK1/2). In contrast, selenite exposure caused S-phase arrest and caspase-independent apoptotic DNA fragmentation, which were associated with decreased expression of p27kip1 and p21cip1 and increased phosphorylation of AKT, JNK1/2, and p38MAPK. Although apoptosis induction by MSeA exposure was not sensitive to superoxide dismutase added into the cell culture medium, cell detachment and DNA nucleosomal fragmentation induced by selenite exposure were greatly attenuated by this enzyme, supporting a chemical mediator role of superoxide for these processes. Despite a temporal relationship of AKT and ERK1/2 de-phosphorylation changes before the onset of PARP cleavage in MSeA-exposed cells, experiments with phosphatidylinositol 3-kinase inhibitors wortmannin and LY294002 did not show an enhancing effect of specific blocking of AKT on MSeA-induction of PARP cleavage. Taken together, exposure of DU145 cells to MSeA versus selenite induced differential patterns of cell cycle arrest and apoptosis execution as well as distinct patterns of effects on AKT, ERK1/2, JNK1/2, and p38MAPK phosphorylation and p27kip1 and p21cip1 expression. Multiple molecular pathways are likely differentially targeted by selenium metabolite pools to mediate cancer chemoprevention.
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PMID:Distinct effects of methylseleninic acid versus selenite on apoptosis, cell cycle, and protein kinase pathways in DU145 human prostate cancer cells. 1248 29

The novel mitogen/extracellular-signal-regulated kinase kinase 5/extracellular signal-regulated kinase-5 (MEK5/ERK5) pathway has been implicated in the regulation of cellular proliferation. MEK5 expression has been detected in prostate cancer cells, although the significance of the MEK5/ERK5 pathway in human prostate cancer has not been tested. We examined MEK5 expression in 127 cases of prostate cancer and 20 cases of benign prostatic hypertrophy (BPH) by immunohistochemistry and compared the results to clinical parameters. We demonstrated that MEK5 expression is increased in prostate cancer as compared to benign prostatic tissue. Strong MEK5 expression correlates with the presence of bony metastases and less favourable disease-specific survival. Furthermore, among the patients with high Gleason score of 8-10, MEK5 overexpression has an additional prognostic value in survival. MEK5 transfection experiments confirm its ability to induce proliferation (P < 0.0001), motility (P = 0.0001) and invasion in prostate cancer cells (P = 0.0001). MEK5 expression drastically increased MMP-9, but not MMP-2 mRNA expression. Luciferase report assays suggest that the -670/MMP-9 promoter is upregulated by MEK5 and electromobility shift assay further suggests the involvement of activator protein-I (AP-1), but not the NF-kappa B, binding site in the MMP-9 promoter. Using an AP-1 luciferase construct, activation of MEK5 was confirmed to enhance AP-1 activities up to twofold. Taken together, our results establish MEK5 as a key signalling molecule associated with prostate carcinogenesis. As the MEK5/ERK5 interaction is highly specific, it represents a potential target of therapy.
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PMID:MEK5 overexpression is associated with metastatic prostate cancer, and stimulates proliferation, MMP-9 expression and invasion. 1261 64


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