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)

Toll-like receptors (TLRs) are known to play a key role in the innate immune system particularly in inflammatory response against invading pathogens. Recent reports strongly indicate that they play important roles in cancer cells. Prostate cancer represents one of the most common cancer for which no cure is available once metastatic and androgen refractory. Since TLR3 has been recently suggested as a possible therapeutic target in some cancer cell lines, we studied TLR3 expression and functionality in two human prostate cancer cell lines, LNCaP and PC3. We report that both cell lines express TLR3 and that the TLR3 agonist poly (I:C) activates mitogen-activated protein kinases and induces inhibition of proliferation as well as caspase-dependent apoptosis. By using pharmacological and genetic approaches, we demonstrate the involvement of TLR3 in poly (I:C)-induced effects. We also show that a novel interferon-independent pathway involving protein kinase C (PKC)-alpha activation, upstream of p38 and c-jun N-terminal kinase, is responsible for poly (I:C) pro-apoptotic effects on LNCaP cells. To our knowledge, this is the first report describing a role of PKC-alpha in poly (I:C)-mediated apoptosis. The comprehension of the mechanisms underlying TLR3-mediated apoptosis can contribute tools to develop new agonists useful for the treatment of prostate cancer.
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PMID:Toll-like receptor 3 triggers apoptosis of human prostate cancer cells through a PKC-alpha-dependent mechanism. 1856 14

Antrodia camphorata (AC) has been used as a health supplement in Asia to control different cancers; however, the cellular mechanisms of its effects are unclear. The effect of AC on cultured human prostate cancer cells (PC3) has not been explored. This study examined the effect of AC on viability, apoptosis, mitogen-activated protein kinases (MAPKs) phosphorylation and Ca2+ handling in PC3 cells. AC at concentrations of 5-50 microg/ml did not affect cell viability, but at 100-200 microg/ml decreased viability and induced apoptosis in a concentration-dependent manner. AC at concentrations of 25-200 microg/ml did not alter basal [Ca2+]i, but at a concentration of 25 microg/ml decreased the [Ca2+]i increases induced by ATP, bradykinin, histamine and thapsigargin. ATP, bradykinin and histamine increased cell viability whereas thapsigargin decreased it. AC (25 microg/ml) pretreatment inhibited ATP-, bradykinin-, and histamine-induced enhancement on viability, but reversed thapsigargin-induced cytotoxicity. Immunoblotting showed that AC (200 microg/ml) did not induce the phosphorylation of ERK, JNK, and p38 MAPKs. Collectively, in PC3 cells, AC exerted multiple effects on viability and [Ca2+]i, caused apoptosis via pathways unrelated to [Ca2+]i signal and phosphorylation of ERK, JNK and p38 MAPKs.
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PMID:Effects of antrodia camphorata on viability, apoptosis, and [Ca2+]i in PC3 human prostate cancer cells. 1866 10

Akt/mammalian target of rapamycin (mTOR) signaling plays an important role in tumorigenesis and is dysregulated in many tumors, especially metastatic prostate cancers. Curcumin has been shown to effectively prevent or inhibit prostate cancer in vivo and inhibit Akt/mTOR signaling in vitro, but the mechanism(s) remains unclear. Here, we show that curcumin concentration- and time-dependently inhibited the phosphorylation of Akt, mTOR, and their downstream substrates in human prostate cancer PC-3 cells, and this inhibitory effect acts downstream of phosphatidylinositol 3-kinase and phosphatidylinositol-dependent kinase 1. Overexpression of constitutively activated Akt or disruption of TSC1-TSC2 complex by small interfering RNA or gene knockout only partially restored curcumin-mediated inhibition of mTOR and downstream signaling, indicating that they are not the primary effectors of curcumin-mediated inhibition of Akt/mTOR signaling. Curcumin also activated 5'-AMP-activated protein kinase and mitogen-activated protein kinases; however, inhibition of these kinases failed to rescue the inhibition by curcumin. Finally, it was shown that the inhibition of Akt/mTOR signaling by curcumin is resulted from calyculin A-sensitive protein phosphatase-dependent dephosphorylation. Our study reveals the profound effects of curcumin on the Akt/mTOR signaling network in PC-3 cells and provides new mechanisms for the anticancer effects of curcumin.
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PMID:Curcumin inhibits Akt/mammalian target of rapamycin signaling through protein phosphatase-dependent mechanism. 1879 Jul 44

Androgen receptor (AR) signaling is involved in the development and progression of prostate cancer. Tumor microvasculature contributes to continual exposure of prostate cancer cells to hypoxia-reoxygenation, however, the role of hypoxia-reoxygenation in prostate cancer progression and modulation of AR signaling is not understood. In this study, we evaluated the effects of hypoxia-reoxygenation in LNCaP cells, a line of hormone responsive human prostate cancer cells. Our results demonstrate that hypoxia-reoxygenation resulted in increased survival, higher clonogenicity and enhanced invasiveness of these cells. Moreover, hypoxia-reoxygenation was associated with an increased AR activity independent of androgens as well as increased hypoxia inducible factor (HIF-1alpha) levels and activity. We also observed that the activation of p38 mitogen-activated protein (MAP) kinase pathway was an early response to hypoxia, and inhibition of p38 MAP kinase pathway by variety of approaches abolished hypoxia-reoxygenation induced increased AR activity as well as increased survival, clonogenicity and invasiveness. These results demonstrate a critical role for hypoxia-induced p38 MAP kinase pathway in androgen-independent AR activation in prostate cancer cells, and suggest that hypoxia-reoxygenation may select for aggressive androgen-independent prostate cancer phenotype.
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PMID:Hypoxia-associated p38 mitogen-activated protein kinase-mediated androgen receptor activation and increased HIF-1alpha levels contribute to emergence of an aggressive phenotype in prostate cancer. 1915 63

Overexpression of epidermal growth factor receptor (EGFR) and mutation of pten tumor suppressor gene in human cancer cells leads to activated EGFR downstream signaling including PI3-kinase/AKT (PI3K/AKT) and/or mitogen-activated protein kinases (RAS/RAF/MAPK) and have been linked to resistance to anti-EGFR targeted therapies. Cetuximab is a chimeric IgG1 monoclonal antibody that binds the EGFR with high specificity and have been developed as promising therapeutic anticancer treatments in several solid tumors, including colorectal and head and neck squamous cell carcinomas. Cetuximab activity is related to PI3K/AKT and RAS/RAF/MAPK signaling pathways functionality and its activity has been shown to be higher in wild-type KRAS tumors. To study the influence of PTEN expression on cell response to cetuximab, we used wild-type KRAS, PTEN-null, EGFR overexpressing PC3 prostate cancer cells. Reintroduction of PTEN significantly reduced the constitutive overexpression of phosphorylated-AKT (p-AKT) and downstream kinases (p-GSK3beta and p-P70S6 kinase) as well as phosphorylated-ERK1/2 (p-ERK1/2) and consequently significantly restored cetuximab-induced cell growth inhibition and apoptosis induction. Taken together, the results achieved in the present study show that PTEN controls the cellular response to cetuximab in KRAS wild-type prostate carcinoma PC3 cells through the regulation of AKT phosphorylation and restoration of the functionality of EGFR downstream signaling. Extrapolation of these findings to clinical situation, suggests that the assessment of EGFR downstream signaling functionality could be proposed as a diagnostic response predictive marker for anti-EGFR targeted therapies.
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PMID:PTEN expression controls cellular response to cetuximab by mediating PI3K/AKT and RAS/RAF/MAPK downstream signaling in KRAS wild-type, hormone refractory prostate cancer cells. 1921 33

As part of our effort to understand the mechanism underlying alpha-tocopheryl succinate [vitamin E succinate (VES)]-mediated antitumor effects, we investigated the signaling pathway by which VES suppresses androgen receptor (AR) expression in prostate cancer cells. VES and, to a greater extent, its truncated derivative TS-1 mediated transcriptional repression of AR in prostate cancer cells but not in normal prostate epithelial cells; a finding that underscores the differential susceptibility of normal versus malignant cells to the antiproliferative effect of these agents. This AR repression was attributable to the ability of VES and TS-1 to facilitate the proteasomal degradation of the transcription factor Sp1. This mechanistic link was corroborated by the finding that proteasome inhibitors or ectopic expression of Sp1 protected cells against drug-induced AR ablation. Furthermore, evidence suggests that the destabilization of Sp1 by VES and TS-1 resulted from the inactivation of Jun N-terminal kinases (JNKs) as a consequence of increased phosphatase activity of protein phosphatase 2A (PP2A). Stable transfection of LNCaP cells with the dominant-negative JNK1 plasmid mimicked drug-induced Sp1 repression, whereas constitutive activation of JNK kinase activity or inhibition of PP2A activity by okadaic acid protected Sp1 from VES- and TS-1-induced degradation. From a mechanistic perspective, the ability of VES and TS-1 to activate PP2A activity underscores their broad spectrum of effects on multiple signaling mechanisms, including those mediated by Akt, mitogen-activated protein kinases, nuclear factor kappaB, Sp1 and AR. This pleiotropic effect in conjunction with low toxicity suggests the translational potential for developing TS-1 into potent PP2A-activating agents for cancer therapy.
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PMID:alpha-Tocopheryl succinate and derivatives mediate the transcriptional repression of androgen receptor in prostate cancer cells by targeting the PP2A-JNK-Sp1-signaling axis. 1942 15

Apoptosis, a form of cell death, is a fundamental process for the development and maintenance of multicellular organisms that promotes the removal of damaged, senescent or unwanted cells. Induction of cancer cell apoptosis is an important strategy of anticancer therapy. In this study, we examined if melatonin, the main secretory product of the pineal gland, inhibited the growth of prostate cancer cells (LNCaP) and promoted apoptosis via mitogen-activated protein kinases (MAPKs), which are closely associated with apoptosis and survival. Melatonin treatment significantly inhibited the growth of LNCaP cells in a dose- and time-dependent manner. It clearly induced both an early stage of apoptosis (propidium iodide(-), FITC Annexin-V(+)) and a late apoptosis/secondary necrosis (propidium iodide(+) and FITC Annexin-V(+)), which indicated induction of serial stages of apoptosis in cells. Moreover, melatonin markedly activated c-JUN N-terminal kinase (JNK) and p38 kinase, whereas extracellular signal-regulated kinase (ERK) was not responsive to melatonin. Treatment with MAPK inhibitors, PD98059 (ERK inhibitor), SP600125 (JNK inhibitor) and SB202190 (p38 inhibitor), confirmed that melatonin-induced apoptosis was JNK- and p38-dependent, but ERK-independent. In the presence of PD98059, caspase-3 activity increased, while levels of Bax/cytochrome c (Cyt c) and Bcl-2 decreased. These effects were opposite to those observed with SP600125 and SB202190 treatments. Together, these results strongly suggest that JNK and p38 activation directly participate in apoptosis induced by melatonin. Thus, melatonin may be of promise for anti-prostate cancer strategies.
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PMID:Melatonin induces apoptotic death in LNCaP cells via p38 and JNK pathways: therapeutic implications for prostate cancer. 1952 39

The excessive proliferation and migration of synoviocytes are well-characterized phenomena that play key roles in the pathophysiology of rheumatoid arthritis (RA). Melatonin has been shown to have potent anti-proliferative effect in various cancer cells such as breast and prostate cancer cells. In this study, we examined the role of melatonin on synoviocyte proliferation in primary cultured human fibroblast-like synoviocytes (FLSs) by analyzing protein expression of P21(CIP1) (P21) and P27(KIP1) (P27), the cyclin-dependent kinase inhibitors that are important in cell cycle control, and the phosphorylation of mitogen-activated protein kinases (MAPKs). RA-FLS proliferation was determined by a [(3)H]-thymidine incorporation assay. Western blot analysis was applied to examine the underlying mechanisms of melatonin's effect. Melatonin inhibited RA-FLS proliferation in a dose-dependent manner. It reduced proliferation of passage 2 FLSs by 25% at 10 microm and by nearly 40% at 100 microm concentrations. The inhibitory effect of melatonin on RA-FLS proliferation was also observed in passages 4 and 6. Melatonin upregulated the expression levels of P21 and P27 dose-dependently (24 hr), induced the phosphorylation of extracellular signal-regulated protein kinase (ERK) time-dependently (10 microm), but did not affect phosphorylation of P38 in RA-FLSs. In addition, the expression of P21 and P27 triggered by melatonin was inhibited by the pretreatment of the ERK inhibitor, PD98059 (10 microm). The anti-proliferative action of melatonin in RA-FLSs was also blocked by PD98059. Taken together, these results suggest that melatonin exerts the inhibitory effect of the proliferation of RA-FLSs through the activation of P21 and P27 mediated by ERK. Hence we suggest that melatonin could be used as a therapeutic agent for the treatment of RA.
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PMID:Melatonin inhibits human fibroblast-like synoviocyte proliferation via extracellular signal-regulated protein kinase/P21(CIP1)/P27(KIP1) pathways. 1953 37

Inflammation has increasingly been recognized as a critical component influencing tumor growth. Recent reports have revealed conflicting evidence for the role of Toll-like receptors (TLR) in modulating tumorigenesis. In our study, we implicate TLR3 in mediating immune surveillance with increased growth of implanted transgenic adenocarcinoma of the mouse prostate (TRAMP) tumors in TLR3(-/-) compared with TLR3(+/+) mice. Activation of TLR3 by polyinosinic-polycytidylic acid (polyI:C) leads to induction of multiple inflammatory pathways, including NF-kappaB, mitogen-activated protein kinases, and interferon (IFN) regulatory factors. We explored the potential of TLR3 stimulation in prostate cancer immunotherapy and showed that treatment with polyI:C can strongly suppress both s.c. implanted TRAMP tumors in syngenic mice as well as orthotopic prostate cancers in TRAMP C57Bl6 x FvB F1 Tg(+/-) transgenic mice. Treated tumors remained well differentiated to moderately differentiated with increased infiltration of T lymphocytes and natural killer (NK) cells compared with poorly differentiated adenocarcinoma observed in untreated tumors. Like TLR3(-/-) mice, IFN-alpha receptor 1 (IFNAR1)(-/-) mice exhibited reduced tumor surveillance and impaired tumor suppression following polyI:C treatment. We observed that type I IFN-dependent induction of cytokines was responsible for NK activation, with depletion of NK cells leading to increased tumor growth as well as expansion of CD4(+)CD25(+)Foxp3(+) T regulatory lymphocytes. Our study therefore delineates the importance of IFNAR-dependent functions in TLR3-mediated tumor suppression and supports the use of TLR3 agonists for prostate cancer immune-based therapies.
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PMID:Toll-like receptor 3-mediated suppression of TRAMP prostate cancer shows the critical role of type I interferons in tumor immune surveillance. 2023 80

Fibroblast growth factor-2 (FGF-2) is highly expressed in prostate cancer. It promotes tumour progression through multiple pathways including those of signal transducers and activators of transcription factor 3 (STAT3), mitogen-activated protein kinases (MAPKs) and Akt. In previous studies, we have reported that STAT3 phosphorylation inversely correlates with suppressor of cytokine signalling-3 (SOCS-3) expression in prostate cancer cells. Recently, it has become evident that SOCS-3-negative regulation is not only limited to the interleukin-6 (IL-6) receptor. We hypothesised that SOCS-3 interferes with FGF signalling, thus influencing the outcome of its action in prostate cancer cells. For this purpose, we treated DU-145 and LNCaP-IL-6+ cells with increasing concentrations of FGF-2, and verified protein phosphorylation. In the presence of FGF-2, neither STAT3, STAT1, nor Akt could be phosphorylated. Solely the p44/p42 MAPK pathway was activated after FGF-2 stimulation. We show for the first time that SOCS-3 interferes with the FGF-2 signalling pathway by modulating p44 and p42 phosphorylation in prostate cancer cells. Decreased SOCS-3 protein expression results in increased MAPK phosphorylation, whereas SOCS-3 overexpression leads to a decreased cellular proliferation and migration. On the basis of the present results, we propose that SOCS-3 is a novel modulator of FGF-2-regulated cellular events in prostate cancer.
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PMID:SOCS-3 antagonises the proliferative and migratory effects of fibroblast growth factor-2 in prostate cancer by inhibition of p44/p42 MAPK signalling. 2033 9


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