Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0376358 (prostate cancer)
 59,338 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Androgen-dependent prostate cancer cells eventually progress to androgen -independent cells after hormonal manipulation. Due to chemotherapeutic drug resistance and toxic side effects, new targets for antineoplastic therapy are urgently needed. In the present study, cerulenin, a fatty acid synthase inhibitor, was used to induce the death of androgen-independent prostate cancer cells. Cerulenin induces the apoptosis of TSU-prl cells based upon the temporal sequence of DNA fragmentation, morphologic changes and loss of cell viability. During apoptotic process induced by the agents, expression of cyclin-dependent kinase inhibitors p21 and p27 increased, whereas expression of cyclin D1 decreased. Flow cytometric analysis showed that the treatment resulted in a block in G2/M of the cell cycle. These results demonstrated that inhibition of fatty acid synthesis could be a target to treat hormone-independent prostate cancer cells via apoptosis, and cyclin-dependent kinase inhibitors played some role during apoptotic pathway.
 ...
PMID:Apoptosis of androgen-independent prostate cell line induced by inhibition of fatty acid synthesis. 949 73

Prostate cancer (PCA) is the most common nonskin malignancy and the second leading cause of cancer deaths in United States males. One practical and translational approach to control PCA is to define a mechanism-based anticarcinogenic agent(s). Recently, we showed that silymarin, a flavonoid antioxidant isolated from milk thistle, possesses exceptionally high to complete protective effects against experimentally induced tumorigenesis. Because the epidermal growth factor receptor (erbB1) and other members of the erbB family have been shown to play important roles in human PCA, efforts should be directed to identify inhibitors of this pathway for PCA intervention. In this study, we assessed whether silymarin inhibits erbB1 activation and associated downstream events and modulates cell cycle regulatory proteins and progression, leading to growth inhibition of human prostate carcinoma DU145 cells. Treatment of serum-starved cells with silymarin resulted in a significant inhibition of transforming growth factor alpha-mediated activation of erbB1 but no change in its protein levels. Silymarin treatment of cells also resulted in a significant decrease in tyrosine phosphorylation of an immediate downstream target of erbB1, the adapter protein SHC, together with a decrease in its binding to erbB1. In the studies analyzing cell cycle regulatory molecules, silymarin treatment of cells also resulted in a significant induction of cyclin-dependent kinase inhibitors (CDKIs) Cip1/p21 and Kip1/p27, concomitant with a significant decrease in CDK4 expression, but no change in the levels of CDK2 and CDK6 and their associated cyclins E and D1, respectively. Cells treated with silymarin also showed an increased binding of CDKIs with CDKs, together with a marked decrease in the kinase activity of CDKs and associated cyclins. In additional studies, treatment of cells grown in 10% serum with anti-epidermal growth factor receptor monoclonal antibody clone 225 or different doses of silymarin also resulted in significant inhibition of constitutive tyrosine phosphorylation of both erbB1 and SHC but no change in their protein levels. Furthermore, whereas silymarin treatment resulted in a significant increase in the protein levels of both Cip1/p21 and Kip1/p27, monoclonal antibody 225 showed an increase only in Kip1/p27. These findings suggest that silymarin also inhibits constitutive activation of erbB1 and that the observed effect of silymarin on an increase in CDKI protein levels is mediated via inhibition of erbB1 activation only in the case of Kip1/p27; however, additional pathways independent of inhibition of erbB1 activation are possibly responsible for the silymarin-caused increase in Cip1/p21 in DU145 cells. In other studies, silymarin treatment also induced a G1 arrest in the cell cycle progression of DU145 cells and resulted in a highly significant to complete inhibition of both anchorage-dependent and anchorage-independent growth of DU145 cells in a dose- and time-dependent manner. Taken together, these results suggest that silymarin may exert a strong anticarcinogenic effect against PCA and that this effect is likely to involve impairment of erbB1-SHC-mediated signaling pathway, induction of CDKIs, and a resultant G1 arrest.
 ...
PMID:A flavonoid antioxidant, silymarin, inhibits activation of erbB1 signaling and induces cyclin-dependent kinase inhibitors, G1 arrest, and anticarcinogenic effects in human prostate carcinoma DU145 cells. 958 34

Loss of expression or mutational deletion of the cyclin-dependent kinase inhibitor p27(Kip1) has recently been implicated in malignant development. In this study, we investigated the relationship between p27(Kip1) protein expression and tumor grade in human prostate cancer by conducting an immunohistochemical analysis in a series of normal prostate, benign prostatic hyperplasia, and malignant prostate cancer specimens. The proliferative activity of prostatic tumors was determined on the basis of the Ki-67 nuclear antigen staining. A uniformly intense immunoreactivity for p27(Kip1) was localized to the nuclei of glandular epithelial cells of normal prostates. The benign glandular epithelia exhibited moderate immunostaining. In the malignant prostate tissue, however, a heterogeneous pattern of substantially reduced p27(Kip1) immunoreactivity was found among the glandular epithelial cells. The majority of primary prostate cancer specimens (68%) were totally negative for p27(Kip1) immunoreactivity, whereas the rest exhibited a significantly decreased p27(Kip1) expression, compared with the normal prostate (P < 0.01). Moreover, there was progressively diminished p27(Kip1) immunostaining with increased tumor grade. This loss of p27(Kip1) was associated with an increase in the proliferative index of prostatic tumors (r = 0.88). There was no significant relationship between p27(Kip) loss and the transforming growth factor beta receptor status of prostatic adenocarcinomas. These results indicate that frequent loss of the cyclin-dependent kinase inhibitor p27(Kip1) in human prostate cancer cells correlates with advancing histological aggressiveness, implicating deregulation of p27(Kip1) in prostate tumor progression.
 ...
PMID:Loss of the cyclin-dependent kinase inhibitor p27(Kip1) protein in human prostate cancer correlates with tumor grade. 981 24

Integrins are a large family of transmembrane receptors that, in addition to mediating cell adhesion, modulate cell proliferation. The beta1C integrin is an alternatively spliced variant of the beta1 subfamily that contains a unique 48-amino acid sequence in its cytoplasmic domain. We have shown previously that in vitro beta1C inhibits cell proliferation and that in vivo beta1C is expressed in nonproliferative, differentiated epithelium and is selectively downregulated in prostatic adenocarcinoma. Here we show, by immunohistochemistry and immunoblotting analysis, that beta1C is coexpressed in human prostate epithelial cells with the cell-cycle inhibitor p27(kip1), the loss of which correlates with poor prognosis in prostate cancer. In the 37 specimens analyzed, beta1C and p27(kip1) are concurrently expressed in 93% of benign and 84%-91% of tumor prostate cells. Forced expression of beta1C in vitro is accompanied by an increase in p27(kip1) levels, by inhibition of cyclin A-dependent kinase activity, and by increased association of p27(kip1) with cyclin A. beta1C inhibitory effect on cell proliferation is completely prevented by p27(kip1) antisense, but not mismatch oligonucleotides. beta1C expression does not affect either cyclin A or E levels, or cyclin E-associated kinase activity, nor the mitogen-activated protein (MAP) kinase pathway. These findings show a unique mechanism of cell growth inhibition by integrins and point to beta1C as an upstream regulator of p27(kip1) expression and, therefore, a potential target for tumor suppression in prostate cancer.
 ...
PMID:p27(kip1) acts as a downstream effector of and is coexpressed with the beta1C integrin in prostatic adenocarcinoma. 992 92

The c-Myc oncoprotein is a transcription factor involved in cellular transformation. We previously found (M. V. Blagosklonny, et al., Cancer Res., 57: 320-325, 1997) that exposure of human SkBr3 breast cancer and LNCaP prostate cancer cells to 12-O-tetradecanoylphorbol-13-acetate (TPA) led to a growth arrest associated with the up-regulation of the cyclin-dependent kinase inhibitor p21(WAF1/cIP1) and the inhibition of c-Myc expression. We show here that exogenous c-Myc inhibits p21 expression in SkBr3 and LNCaP cells induced to enter into S-phase. p27 expression was not increased from basal levels in TPA-treated growth-arrested cells. A time course after infection of TPA-arrested cells using a c-Myc-expressing adenovirus revealed that the inhibition of p21 expression preceded entry into S-phase. In contrast, after infection by E2F-1-expressing adenovirus, p21 expression was reduced after the cells entered S-phase. Overexpression of c-Myc reduced the levels of endogenous p21 mRNA, and transfection of c-Myc repressed p21-promoter luciferase-reporter gene expression. The results suggest that the down-regulation of p21 expression may contribute to c-Myc-dependent entry into S-phase, possibly in situations in which growth arrest is associated with increased p21 expression.
 ...
PMID:Overexpression of c-Myc inhibits p21WAF1/CIP1 expression and induces S-phase entry in 12-O-tetradecanoylphorbol-13-acetate (TPA)-sensitive human cancer cells. 1031 92

Reduction in serum prostate-specific antigen (PSA) levels has been proposed as an endpoint biomarker for hormone-refractory human prostate cancer intervention. We examined whether a flavonoid antioxidant silibinin (an active constituent of milk thistle) decreases PSA levels in hormone-refractory human prostate carcinoma LNCaP cells and whether this effect has biological relevance. Silibinin treatment of cells grown in serum resulted in a significant decrease in both intracellular and secreted forms of PSA concomitant with a highly significant to complete inhibition of cell growth via a G1 arrest in cell cycle progression. Treatment of cells grown in charcoal-stripped serum and 5alpha-dihydrotestosterone showed that the observed effects of silibinin are those involving androgen-stimulated PSA expression and cell growth. Silibinin-induced G1 arrest was associated with a marked decrease in the kinase activity of cyclin-dependent kinases (CDKs) and associated cyclins because of a highly significant decrease in cyclin D1, CDK4, and CDK6 levels and an induction of Cip1/p21 and Kip1/p27 followed by their increased binding with CDK2. Silibinin treatment of cells did not result in apoptosis and changes in p53 and bcl2, suggesting that the observed increase in Cip1/p21 is a p53-independent effect that does not lead to an apoptotic cell death pathway. Conversely, silibinin treatment resulted in a significant neuroendocrine differentiation of LNCaP cells as an alternative pathway after Cip1/p21 induction and G1 arrest. Together, these results suggest that silibinin could be a useful agent for the intervention of hormone-refractory human prostate cancer.
 ...
PMID:Silibinin decreases prostate-specific antigen with cell growth inhibition via G1 arrest, leading to differentiation of prostate carcinoma cells: implications for prostate cancer intervention. 1037 42

The cyclin dependent kinase inhibitor p27 binds to and inhibits preferentially S-phase kinases thereby halting cell cycle progression. Loss of p27 expression has been shown to be associated with aggressive behavior in a variety of human epithelial tumors including prostate cancer. In this review, the role of p27 in cell cycle progression as well as its regulation by the ubiquitin-proteasome pathway are discussed. The experimental evidence pointing to the role of p27 as a tumor suppressor gene is outlined. The data generated to date on the prognostic significance of loss of p27 protein expression in human prostate cancers are summarized. Finally, the implications of the changes in p27 expression which occur as a result of androgen ablation in normal and neoplastic prostate are discussed.
 ...
PMID:Role of p27 in prostate carcinogenesis. 1045 77

p27KIP1 is a member of the CIP/KIP family of cyclin-dependent kinase inhibitory proteins that negatively regulate cell proliferation. Recent studies reported decreased p27 expression in breast and colon carcinomas and found that the loss of p27 is associated with a poor prognosis. We report here the results of our immunohistochemical analysis of p27 in human prostate cancer. Formalin-fixed, paraffin-embedded, whole-mount sections of prostate cancer from 73 selected patients treated by radical retropubic prostatectomy were obtained from the Department of Pathology, The Methodist Hospital, Houston, Texas. Ten histologically normal and nine high-grade prostatic intraepithelia neoplasia foci were selected from these whole-mount sections, and nine cases of transplant donor prostates were chosen as controls. Also, 10 prostate cancer metastatic lymph nodes were used to compare with the primary cancer group. Sections were immunostained with a monoclonal antibody against p27 protein using the avidin-biotin complex immunohistochemical method. Immunoactivity was evaluated without knowledge of follow-up and recorded as the p27 labeling index (LI) (defined as the percentage of p27-positive cells among epithelia of the same category). The p27 (LI) in normal prostatic epithelia was 86.4+/-3.5% (the mean +/- the standard error of the mean). In contrast, the p27 immunoreactivity was significantly lower in cancers (LI: 43.5 +/-3.7%, P < .001) and in the high-grade prostatic intraepithelial neoplasia group (LI: 59.3 +/- 3.2%, P < .05). Expression of p27 in the metastatic lymph node group was significantly lower than in the other groups, including the prostate cancer cases and the cases of high-grade intraepithelial neoplasia (LI, 7.0%; P = .05). There was no association of the mean p27 LI with progression after radical prostatectomy. Nonrecurrent cases, with a mean follow-up time of greater than 5 years (n = 45), equalled 41.9%; recurrent cases, with a mean follow-up time of 18.3 months (n = 28), equalled 40.0%. The mean p27 LI was not associated with pathologic stage. Organ-confined specimens (n = 21) equalled 34.2%; cases of extraprostatic extension (n = 24) equalled 46.5%; and samples showing seminal vesicle involvement (n = 14) equalled 47.6%. In 14 cases with lymph node metastases, the mean p27 LI was 48.1% in the primary cancer (P = .2322). There was no association of the mean p27 LI with the Gleason score (P = .4747) nor with the clinical stage (P = .9914).
 ...
PMID:Levels of expression of p27KIP1 protein in human prostate and prostate cancer: an immunohistochemical analysis. 1046 75

The PTEN tumor suppressor gene is frequently inactivated in human prostate cancers, particularly in more advanced cancers, suggesting that the AKT/protein kinase B (PKB) kinase, which is negatively regulated by PTEN, may be involved in human prostate cancer progression. We now show that AKT activation and activity are markedly increased in androgen-independent, prostate-specific antigen-positive prostate cancer cells (LNAI cells) established from xenograft tumors of the androgen-dependent LNCaP cell line. These LNAI cells show increased expression of integrin-linked kinase, which is putatively responsible for AKT activation/Ser-473 phosphorylation, as well as for increased phosphorylation of the AKT target protein, BAD. Furthermore, expression of the p27(Kip1) cell cycle regulator was diminished in LNAI cells, consistent with the notion that AKT directly inhibits AFX/Forkhead-mediated transcription of p27(Kip1). To assess directly the impact of increased AKT activity on prostate cancer progression, an activated hAKT1 mutant was overexpressed in LNCaP cells, resulting in a 6-fold increase in xenograft tumor growth. Like LNAI cells, these transfectants showed dramatically reduced p27(Kip1) expression. Together, these data implicate increased AKT activity in prostate tumor progression and androgen independence and suggest that diminished p27(Kip1) expression, which has been repeatedly associated with prostate cancer progression, may be a consequence of increased AKT activity.
 ...
PMID:Increased AKT activity contributes to prostate cancer progression by dramatically accelerating prostate tumor growth and diminishing p27Kip1 expression. 1082 91

Transcriptional activation of the p53 target genes plays a critical role in the cellular response to DNA damage, hypoxia, cellular stress and other signals regulating the cell cycle and apoptosis. The discovery of new p53 target genes continues to reveal novel mechanisms of action of this multifaceted protein. We used cDNA arrays to search for p53-regulated genes in prostate cancer cells. In this report, we describe robust induction of heat shock protein 27 (hsp27) in prostate cancer cells (DU145, LNCaP, PC3) following wild-type p53 expression from an adenoviral p53 expression vector (AdWTp53). A mutant p53 (R175H)-containing adenoviral expression vector did not induce hsp27. hsp27 expression was not altered in prostate cancer cells following expression of cyclin-dependent kinase inhibitors: p21(waf1/cip1) and p27(kip1) from adenoviral expression vectors. Treatment of cells with staurosporine, an apoptosis-inducing agent, did no affect hsp27 expression. These observations provide evidence that induction of hsp27 expression was wild-type p53-specific and was not due to non-specific effects of cell growth arrest and/or apoptosis. Previous studies and the experiment reported here show induction of hsp27 expression in response to androgen ablation, a physiological state that induces apoptosis in prostatic epithelial cells. The nature of p53 and hsp27 interactions in the regulation of apoptosis and/or cell growth needs to be further defined.
 ...
PMID:p53-dependent induction of heat shock protein 27 (HSP27) expression. 1100 67


1 2 3 4 5 6 7 8 9 10 Next >>