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)

We are interested in the possibility of new prostate cancer therapy that would control tumor malignancy via the induction of terminal cell differentiation. We have previously reported that staurosporine induced remarkable inhibition of cell proliferation and neuronal differentiation in human prostatic cancer TSU-Pr1 cells. In the present study, we investigated the alteration of cyclin-dependent kinase (CDK) activities and cell cycle in differentiated TSU-Pr1 cells. Treatment of TSU-Pr1 cells with staurosporine resulted in G1 arrest and suppression of CDK2 activity. Protein levels of CDK2 were essentially unchanged during this time. p21 protein, however, rapidly increased for 6 hours after treatment with staurosporine. p27 protein also increased gradually for 12 to 72 hours after treatment. CDK2-bound p21 and CDK2-bound p27 also increased. These results suggest that an increase in p21 and p27 protein causes increased binding with CDK2 and inhibition of CDK2 activity. We propose that the complex regulation of CDK2 plays a key role in G1 arrest of TSU-Pr1 cells after treatment with staurosporine.
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PMID:Complex regulation of CDK2 and G1 arrest during neuronal differentiation of human prostatic cancer TSU-Prl cells by staurosporine. 1139 81

Prostate cancer is one of the most common cancers in men and it is the second leading cause of cancer related death in men in the United States. Recent dietary and epidemiological studies have suggested the benefit of dietary intake of fruits and vegetables in lowering the incidence of prostate cancer. A diet rich in fruits and vegetables provides phytochemicals, particularly indole-3-carbinol (I3C), which may be responsible for the prevention of many types of cancer, including hormone-related cancers such as prostate. Studies to elucidate the role and the molecular mechanism(s) of action of I3C in prostate cancer, however, have not been conducted. In the current study, we investigated whether I3C had any effect against prostate cancer cells and, if so, attempts were made to identify the potential molecular mechanism(s) by which I3C elicits its biological effects on prostate cancer cells. Here we report for the first time that I3C inhibits the growth of PC-3 prostate cancer cells. Induction of G1 cell cycle arrest was also observed in PC-3 cells treated with I3C, which may be due to the observed effects of I3C in the up-regulation of p21(WAF1) and p27(Kip1) CDK inhibitors, followed by their association with cyclin D1 and E and down-regulation of CDK6 protein kinase levels and activity. The induction of p21(WAF1) appears to be transcriptionally upregulated and independent of the p53 responsive element. In addition, I3C inhibited the hyperpohosphorylation of the Retinoblastoma (Rb) protein in PC-3 cells. Induction of apoptosis was also observed in this cell line when treated with I3C, as measured by DNA laddering and poly (ADP-ribose) polymersae (PARP) cleavage. We also found an up-regulation of Bax, and down-regulation of Bcl-2 in I3C-treated cells. These effects may also be mediated by the down-regulation of NF-kappaB observed in I3C treated PC-3 cells. From these results, we conclude that I3C inhibits the growth of PC-3 prostate cancer cells by inducing G1 cell cycle arrest leading to apoptosis, and regulates the expression of apoptosis-related genes. These findings suggest that I3C may be an effective chemopreventive or therapeutic agent against prostate cancer.
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PMID:Indole-3-carbinol (I3C) induced cell growth inhibition, G1 cell cycle arrest and apoptosis in prostate cancer cells. 1142 Jul 5

2-Methoxyestradiol (2-ME), an endogenous metabolite of 17beta-estradiol, is present in human blood and urine. Here we show for the first time that 2-ME significantly inhibited the growth of normal prostate epithelial cells and androgen-dependent LNCaP and androgen-independent DU145 prostate cancer cells. This growth inhibition was accompanied by a twofold increase in the G(2)/M population, with a concomitant decrease in the G(1) population, as shown by cell-cycle analysis. 2-ME treatment affected the cell-cycle progression of prostate cancer cells specifically by blocking cells in the G(2) phase. Immunoblot analysis of the key cell-cycle regulatory proteins in the G(2)/M phase showed a 14-fold increase in the expression of p21 and an eightfold increase in the expression of p34 cell division cycle 2 (cdc2). We also found an accumulation of phosphorylated cdc2 after 2-ME treatment. Furthermore, Wee 1 kinase was detectable after 2-ME treatment. 2-ME treatment also led to an increase in the activity of caspase-3, followed by apoptosis, as shown by terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate-biotin nick end-labeling and fluorescein isothiocyanate-poly(ADP-ribose) polymerase assay. Estrogen receptor levels did not change after treatment with 2-ME. Examination of the signaling pathways that mediate 2-ME-induced apoptosis showed reduction in the level of p53 expression and its DNA-binding activity. Given the fact that p53 mutations are common in patients with metastatic prostate cancer, our finding that 2-ME-mediated growth inhibition of human prostate cancer cells occurred in a p53-independent manner has considerable clinical significance. These findings, combined with the limited toxicity of 2-ME, may have significant implications for alternative treatment of advanced prostate cancer.
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PMID:2-methoxyestradiol blocks cell-cycle progression at G(2)/M phase and inhibits growth of human prostate cancer cells. 1147 20

PC SPES (BotanicLab, Brea, California) an herbal supplement for patients with prostate cancer, is composed of 7 highly concentrated Chinese herbs and 1 US herb. It was developed in seeking positive attributes of Chinese and Western medicine for cancer treatment. Chemical standardization of this composition showed that baicalin is the most abundant active compound. Several reports on phase 2 clinical studies of PC SPES suggest that it is a well-tolerated active treatment for androgen-independent prostate cancer. In this report, data obtained from various laboratory experiments will be presented to elucidate the in vitro mechanism. Profound biologic effects of PC SPES on prostate cancer cells were observed on both androgen-dependent (LNCap) and androgen-independent (DU-145) cell lines. These effects include the following: (1) induction of cell apoptosis and cell cycle modulation; (2) inhibition of cell proliferation; (3) downregulation of bcl-2, bcl-6, proliferating cell nuclear antigen, and prostate-specific antigen proteins; (4) downregulation of androgen receptor (AR); and (5) upregulation of p53, bax, and p21 proteins. Concurrent animal studies using 2 different models, Copenhagen rats and nude mice, confirmed a dose-dependent suppressive effect of PC SPES on tumor volumes and tumor progression. Our results show that the cytotoxic and cytostatic properties of PC SPES are not entirely dependent on the presence of AR. The antitumor mechanism of PC SPES is complex. It involves multiple metabolic pathways, such that the whole extract acts on redundant mechanisms, which otherwise will permit cell survival if a single-target agent is used.
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PMID:In vitro mechanism of PC SPES. 1150 43

Osteoblastic metastases are common in lethal prostate cancer. Effective therapy for bone metastases is lacking. Thus, developing an appropriate in vitro screening system is critical to prioritize which of the newly developed agents should undergo additional expensive and time-consuming in vivo evaluation in bone metastases animal models. In the past, such in vitro screening evaluated the response of prostate cancer cells to chemotherapeutic agents in monoculture without the presence of osteoblasts. In such monoculture, prostate cancer cells have a high (i.e., >90%) proliferative growth fraction. In contrast, the growth fraction (i.e., mean: 7.1 +/- 0.8%; median: 3.1%) in 117 metastatic sites of prostate cancer obtained from 11 androgen ablation failing patients at "warm" autopsy was found to be >10-fold lower. To better mimic the lower growth fraction observed clinically, LNCaP human prostate cancer cells were cocultured with membrane-separated hFOB human osteoblasts. Such coculturing significantly lowered the growth fraction of the LNCaP cells (i.e., from >90 to <30%) without enhancing their low rate (i.e., <5%) of apoptosis. This lowering of the growth fraction was documented using flow cytometry, Ki-67 immunohistochemistry, and 5-bromo-2-deoxyuridine incorporation. Using RNase protection assays, it was documented that coculture with osteoblasts causes enhanced p53, p27, and p21 expression leading to a decrease in the number of LNCaP cells entering the cell cycle (i.e., enhanced number of LNCaP cells in G(0)-G(1) and a decrease in S and G(2)-M and thus the growth fraction). This osteoblast-induced enhanced G(0)-G(1) checkpoint control affected the chemosensitivity of LNCaP cells. This was documented by coculturing LNCaP cells with hFOB cells to condition the medium for 3 days to lower the growth fraction to <30% before exposing the LNCaP cells for 48 h to various concentrations of Taxol, doxorubicin, or thapsigargin (TG). In standard high (i.e., >90%) growth fraction cultures (i.e., cultures in the absence of osteoblast-conditioned medium), there was a dose-dependent and significant (P < 0.05) increase in apoptosis of LNCaP cells exposed to Taxol or doxorubicin. In contrast, even the highest dose of Taxol (1 microM) did not enhance apoptosis of lower growth fraction LNCaP cells cultured in osteoblast-conditioned medium. Similarly, only the highest concentration of doxorubicin (1 microM) enhanced apoptosis in lower growth fraction cells. In contrast, 100 nM TG induced high levels of apoptosis in both lower and high-growth fraction LNCaP cultures. These results demonstrate that the osteoblast/LNCaP coculture system is a better in vitro screen than monoculture to identify proliferation-independent agents for the treatment of prostate cancer bone metastases, and TG is such an agent.
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PMID:Therapeutic implications of enhanced G(0)/G(1) checkpoint control induced by coculture of prostate cancer cells with osteoblasts. 1152 28

Lovastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, induces growth arrest in a variety of cancer cell lines. Its mechanism of action, however, has not been completely elucidated. E2F-1 is thought to act as an oncogene and a tumour suppressor, with its action probably dependent upon the cellular context. We have shown in this study that transcriptional regulation and proteasomal degradation of E2F-1 are critical regulatory events in lovastatin-induced cell death. Accompanying this is a reduction in the E2F-1-regulated expression of cell cycle genes such as c-myc, cyclin D1, cyclin A and cyclin B1. Cell cycle analysis demonstrated that the accumulation of apoptotic cells was preceded by a progressive decrease in the S-phase cell population in response to lovastatin. Although expression of E2F-1 was reduced in three prostate cancer cell lines-PC-3, LNCaP and DU-145-the p21 and p27 protein levels were not increased in all the cell lines treated, suggesting that increase in p21 and p27 protein expression per se is not responsible for lovastatin-mediated down-regulation of E2F-1. The subsequent apoptotic death of these cells in the presence of lovastatin can be prevented by forced ectopic expression of E2F-1. Taken together, these facts imply that E2F-1 is the target of an HMG-CoA inhibitor and critical cell death mediator in prostate cancer cells.
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PMID:Lovastatin-induced E2F-1 modulation and its effect on prostate cancer cell death. 1157 16

The effects of selenium exposure were studied in LNCaP human prostate cancer cells, and this same cell line adapted to selenium over 6 months to compare acute versus chronic effects of sodium selenite, the latter most closely resembling human clinical trials on the effects of selenium in cancer prevention and therapy. Our results demonstrated that oxidative stress was induced by sodium selenite at high concentrations in both acute and chronic treatments, but outcomes were different. After acute exposure to selenite, cells exhibited mitochondrial injury and cell death, mainly apoptosis. After chronic exposure to selenite, cells showed growth inhibition caused by cell cycle arrest, increased numbers of mitochondria and levels of mitochondrial enzymes, and only minimal induction of apoptosis. Immunoblotting analysis revealed that multiple proteins were up-regulated by chronic exposure to selenite. Among them, only up-regulation of manganese superoxide dismutase and the cyclin-dependent kinase inhibitor p21(Waf1/Cip1), proteins known to be redox sensitive and to have cell cycle regulatory functions, correlated with cell growth inhibition. Our results in selenite-adapted cells suggest that selenium may exert its effects in human prostate cancer cells by altering intracellular redox state, which subsequently results in cell cycle block.
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PMID:Redox-mediated effects of selenium on apoptosis and cell cycle in the LNCaP human prostate cancer cell line. 1158 38

An androgen-independent (AI) prostate cancer cell line, derived recently from an LNCaP cell line maintained in androgen-poor conditions, has properties resembling a subgroup of advanced prostate cancers in that it has an overexpressed androgen receptor (AR), undetectable levels of p21WAF1 and prostate-specific antigen, and is resistant to apoptosis. The loss of prostate-specific antigen expression but not the p21WAF1 is attributable to gene silencing by hypermethylation. The high AR and undetectable p21WAF1 of AI cells, and lower AR but highly expressed p21WAF1 of androgen-dependent parental LNCaP cells, suggest a possibility of a functional link between these two proteins. Therefore, we examined the impact the modulation of AR will have on the expression of p21WAF1. Treatment of androgen-dependent cells with an androgen agonist, R1881, increased the AR protein level, whereas it simultaneously reduced the endogenous p21WAF1-protein 8-fold and the activity of a transiently transfected p21-promoter-reporter 10-fold. The down-regulation of p21WAF1 promoter appeared to be ARE mediated, dependent on AR, and not cell-type specific. Furthermore, a reduction of the AR level in AI cells by AR-antisense oligonucleotide increased the p21WAF1 promoter-reporter activity by approximately 4-fold, confirming a functional link between these two proteins. A strong, direct induction of p21WAF1 expression achieved by treatment of AI cells with trichostatin A produced a partial reversion of the AI phenotype evidenced by increased sensitivity of these cells to paclitaxel-induced apoptosis. Moreover, a reduction of AR level by antisense treatment, which also increased p21WAF1 expression, partially restored the androgen dependence of AI cells for growth. The functional link between AR dosage and p21WAF1 expression suggests that therapeutic reduction of AR protein in advanced prostate cancers with elevated AR levels may re-establish their hormone dependence and improve therapeutic response to repeated hormonal ablation and/or induction of apoptosis.
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PMID:Overexpressed androgen receptor linked to p21WAF1 silencing may be responsible for androgen independence and resistance to apoptosis of a prostate cancer cell line. 1160 92

Kruppel-like factor 6 (KLF6) is a zinc finger transcription factor of unknown function. Here, we show that the KLF6 gene is mutated in a subset of human prostate cancer. Loss-of-heterozygosity analysis revealed that one KLF6 allele is deleted in 77% (17 of 22) of primary prostate tumors. Sequence analysis of the retained KLF6 allele revealed mutations in 71% of these tumors. Functional studies confirm that whereas wild-type KLF6 up-regulates p21 (WAF1/CIP1) in a p53-independent manner and significantly reduces cell proliferation, tumor-derived KLF6 mutants do not. Our data suggest that KLF6 is a tumor suppressor gene involved in human prostate cancer.
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PMID:KLF6, a candidate tumor suppressor gene mutated in prostate cancer. 1175 79

Cellular senescence has been proposed to be an in vitro and in vivo block that cells must overcome in order to immortalize and become tumorigenic. To characterize these pathways, we focused on changes in the cyclin-dependent kinase inhibitors and their binding partners that underlie the cell cycle arrest at senescence. As a model, we utilized normal human prostate epithelial cell (HPEC) and human uroepithelial cell (HUC) cultures. After 30-40 population doublings cells became growth-arrested in G0/1 with a threefold decrease in Cdk2-associated activity, a point defined as pre-senescence. Temporally following this growth arrest, the cells develop a senescence morphology and express senescence-associated beta-galactosidase (SA-beta-gal). Levels of p16(INK4a) and p57(KIP2) rise in HUCs during progressive passages, whereas only p16 increases in HPEC cultures. The induced expression of p57, similar to p16, produces a senescent-like phenotype. pRB, cyclin D, p19(INK4d) and p27(KIP1) decrease in both cell types. We find that p53, p21(CIP1) and p15(INK4b) are transiently elevated in HPECs and HUCs at the pre-senescent growth arrest, then return to low proliferating levels at terminal senescence. Analysis of p53, p21(CIP1), p15(INK4b), p16(INK4a), and p57(KIP2) reveals altered expression in immortalized, non-tumorigenic HPV16 E6 and E7 prostate lines and in tumorigenic prostate cancer cells. These results indicate: (i) the existence of a subset of growth inhibiting genes elevated at the onset of the senescence, (ii) a distinct class of genes involved in the maintenance of senescence, and (iii) the frequent inactivation of these pathways during immortalization.
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PMID:Role of cyclin-dependent kinase inhibitors in the growth arrest at senescence in human prostate epithelial and uroepithelial cells. 1178 34


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