Biomedical subjects

Charles Y F Young

Publications and source records attributed to Charles Y F Young.

17 recordsLinked to original sources

PubMed2006

Gum mastic inhibits the expression and function of the androgen receptor in prostate cancer cells.

Accumulating evidence suggests that the androgen receptor (AR) may play an important role in the development and progression of prostate cancer. To find new, useful compounds that effectively may attenuate the function of AR in prostate cancer cells, the authors investigated the effect of gum mastic, a natural resin, on AR activity. An androgen-responsive prostate cancer cell line LNCaP was used as a model for this study. Gene transfer, reverse transcriptase-polymerase chain reaction analysis, electrophoretic mobility shift assay, and Western blot analysis were used to test the effect of gum mastic on the expression and function of the AR. To demonstrate the inhibitory effect of gum mastic on the function of the AR, the expression of androgen-regulated genes, including prostate-specific antigen (PSA), human kallikrein 2 (hK2), and NKX3.1 were measured. In addition, transient transfection assays with the PSA promoter and the AR promoter also were used to test the effects of mastic. The results showed that gum mastic inhibited the expression of the AR at the transcriptional level, resulting in the down-regulation of both AR messenger RNA and protein levels. Therefore, the function of the AR was inhibited, as reflected by the reduced expression of NKX3.1 and PSA and by androgen-stimulated growth. Because gum mastic exhibited a strong in vitro potency to attenuate the expression and function of the AR, further investigation will be required to determine whether this naturally occurring substance has in vivo potency to inhibit prostate cancer development.

Androgens↗

PubMed2006

PDLIM4 repression by hypermethylation as a potential biomarker for prostate cancer.

PURPOSE: We analyzed the expression of genes to identify reliable molecular markers in the diagnosis and progression of prostate cancer. EXPERIMENTAL DESIGN: Gene expression profiling was done using HG-U133 set microarrays in 32 prostate cancer and 8 benign tissues of patients with cancer. Expression levels of 11 genes were selected for quantitative real-time PCR evaluation in 52 prostate cancer and 20 benign tissues. Further, to assess transcriptional inactivation, we analyzed the promoter methylation of genes by quantitative methylation-specific PCR in 62 tumor and 36 benign tissues. RESULTS: Our results showed a significant down-regulation in the mRNA expression levels of PRIMA1, TU3A, PDLIM4, FLJ14084, SVIL, SORBS1, C21orf63, and KIAA1210 and up-regulation of FABP5, SOX4, and MLP in prostate cancer tissues by TaqMan real-time PCR. Quantitative methylation-specific PCR of PDLIM4, SVIL, PRIMA1, GSTP1, and PTGS2 detected prostate carcinoma with a sensitivity of 94.7%, 75.4%, 47.4%, 89.5%, and 87.7%, and a specificity of 90.5%, 75%, 54.2%, 95.8%, and 90.2%, respectively. Using this panel of methylation markers in combination, we were able to distinguish between prostate cancer and adjacent benign tissues with sensitivities and specificities of about 90% to 100%. Our data provide evidence of transcriptional repression of the putative tumor suppressor gene PDLIM4 by hypermethylation. CONCLUSIONS: Our analysis revealed differential expression of eight down-regulated and three up-regulated genes, implicating their role in prostate cancer development and progression. We further showed that the hypermethylation of PDLIM4 gene could be used as a sensitive molecular tool in detection of prostate tumorigenesis.

Aged↗

PubMed2005

Perillyl alcohol inhibits the expression and function of the androgen receptor in human prostate cancer cells.

Perillyl alcohol is a hydroxylated monocyclic monoterpene. In animal study, monoterpene has shown to have an anti-tumor effect. The aim of this study is to evaluate whether POH plays an important role in the development and progression of prostate cancer (pCa). We treated LNCaP cells with different concentrations of perillyl alcohol (POH). First of all, we performed cell proliferation assay and prostate-specific antigen (PSA) and human glandular kallikrein (hK2) quantification assays. LNCaP cells were treated with or without POH for Western blot analysis of androgen receptor (AR) and c-Jun. Finally, we performed transient transfection assay by transfecting LNCaP cells-which were treated with or without POH-with pGL-3 luciferase vector containing PSA promoter and AR promoter. We observed inhibition of the expression and function of the AR by POH, through inhibition of androgen-induced cell growth and androgen-stimulated secretion of prostate-specific antigen and hK2, in human pCa cell line LNCaP. In addition, we demonstrated, for the first time, that POH inhibits the transcription activities of the AR gene promoter by over-expression of c-Jun protein. These novel properties of POH strongly suggest that POH could be highly useful for intervention of pCa.

Androgen Receptor Antagonists↗

PubMed2005

Involvement of transcription factor Sp1 in quercetin-mediated inhibitory effect on the androgen receptor in human prostate cancer cells.

The transactivation function of the human androgen receptor (AR) can be regulated by several coregulators that may be either positive or negative. Ubiquitous transcription factor Sp1 not only regulates the basal expression of the AR but also acts as its coregulator. Our previous study has shown that quercetin, one of the main polyphenols, can effectively inhibit the expression and function of the AR. The present study is to address if quercetin may affect Sp1's action on AR transactivation activity in human prostate adenocarcinoma cell lines, LNCaP and PC-3. First, we showed that indeed in transient transfections Sp1 could enhance transcriptional activity of the AR promoter and of androgen upregulated gene promoters, i.e. the prostate-specific antigen and the hK2 genes. Interestingly, the enhancing activity of Sp1 could be repressed by quercetin. The gel shift and western blot analyses indicated that the specific DNA motif binding activity of Sp1 and its protein levels were not altered by quercetin. However, the state of interaction of Sp1 with the AR treated by quercetin plus androgen was different from that by androgen treatment or none as demonstrated by coimmunoprecipitation experiments and glutathione S-transferase (GST) pull-down assays. Moreover, we showed that quercetin caused changes in post-translational modification of AR protein. The above findings strongly suggest that changes induced by quercetin in post-translational modification of the AR and in states of physical interaction of Sp1 with the AR may be critical for the attenuation of AR's function.

Adenocarcinoma↗

PubMed2005

AGR2, an androgen-inducible secretory protein overexpressed in prostate cancer.

AGR2, the human homologue of Xenopus anterior gradient 2 (XAG2), was identified by a suppression subtractive hybridization-based technique as an androgen-inducible gene. There are two AGR2 transcripts, which encode the same secretory protein of 175 amino acids. The androgen induction was time- and dose-dependent, with more than a 10-fold increase in the level of AGR2 mRNA after 48 hr of treatment with 10(-9) M R1881. Expression of AGR2 mRNA was specifically detected in limited human tissue rich in epithelial cells, including the prostate gland. Analysis of 46 microdissected primary prostate adenocarcinoma samples showed that AGR2 mRNA expression was markedly elevated in the majority of tumors as compared to matched adjacent benign tissues. Androgen-induced AGR2 protein expression was demonstrated in LNCaP cells by Western blot analysis with an anti-AGR2 antibody. Immunohistochemistry analysis indicated that AGR2 protein expression was highly restricted to the secretory epithelial cells in the prostate gland. In tissue sections from radical prostatectomy specimens, immunohistochemical staining of AGR2 showed markedly increased expression in high-grade prostatic intraepithelial neoplasia and Gleason pattern 3-4 prostatic adenocarcinoma. Therefore, the androgen-induced secretory protein AGR2 may serve as a potential therapeutic target and/or molecular marker for prostate cancer.

Adenocarcinoma↗

PubMed2005

Decoy androgen-responsive element DNA can inhibit androgen receptor transactivation of the PSA promoter gene.

Chemotherapy, hormonal therapy, or surgery may cause devastating toxic or other side effects. Androgen receptors (ARs) in the cytoplasm are activated by binding with androgen. Androgen-activated ARs bind to a specific genomic DNA sequence, the androgen-responsive element (ARE), and initiate gene expression at the transcriptional level. Even without androgen activation, ARs may have a role in androgen-refractory prostate cancer. Thus, inhibition of AR activity may have therapeutic value. We applied a genetic reporter of the Dual-Luciferase Assay System to test whether a short double-stranded genomic DNA containing prostate-specific antigen (PSA) ARE sequence as decoy DNA would inhibit the function of activated AR. A 21-mer phosphorothioated PSA ARE decoy DNA was synthesized, with a plasmid vector containing the PSA promoter upstream from a luciferase gene, the reporter gene. The promoter and reporter were co-transfected into a human prostate cancer cell line PC3-M with the aid of Lipofectamin 2000. After 24 hr exposure to androgens, the cells were lysed and luciferase activity measured to determine the ARE decoy inhibitory effect on the function of ARs. Luciferase activity was reduced significantly in the ARE decoy transfected cells but not with inactive control decoy. The results demonstrate that ARE decoy DNA can effectively suppress androgen-activated ARs in prostate cancer cells and indicate the potential utility of decoy DNA for developing a novel therapy for prostate cancer.

Androgen Receptor Antagonists↗

PubMed2004

Overexpression of c-Jun induced by quercetin and resverol inhibits the expression and function of the androgen receptor in human prostate cancer cells.

Previously, we reported that quercetin and resveratrol inhibit the function of androgen receptor (AR). Further studies showed that these two polyphenols caused an increase in expression of c-Jun as well as its phosphorylated form in a dose-dependent manner in prostatic cell lines. Gel shift assay showed that induced c-Jun has specific DNA binding activity. Transient transfections demonstrated that c-Jun repressed prostate-specific antigen promoter activity and transcriptional activity of the AR promoter. These results support a mechanism in which overexpressed c-Jun mediates inhibitory effect on the function of AR. These polyphenols might potentially be useful in prostate cancer prevention.

Angiogenesis Inhibitors↗

PubMed2004

Proteomics shows Hsp70 does not bind peptide sequences indiscriminately in vivo.

Heat shock protein 70 (Hsp70) binds peptide and has several functions that include protein folding, protein trafficking, and involvement with immune function. However, endogenous Hsp70-binding peptides had not previously been identified. Therefore, we eluted and identified several hundred endogenously bound peptides from Hsp70 using liquid chromatography ion trap mass spectrophotometry (LC-ITMS). Our work shows that the peptides are capable of binding Hsp70 as previously described. They are generally 8-26 amino acids in length and correspond to specific regions of many proteins. Through computationally assisted analysis of peptides eluted from Hsp70 we determined variable amino acid sequences, including a 5 amino acid core sequence that Hsp70 favorably binds. We also developed a computer algorithm that predicts Hsp70 binding within proteins. This work helps to define what peptides are bound by Hsp70 in vivo and suggests that Hsp70 facilitates peptide selection by aiding a funneling mechanism that is flexible but allows only a limited number of peptides to be processed.

Algorithms↗

PubMed2004

The effects of dietary factors on the androgen receptor and related cellular factors in prostate cancer.

It has been strongly suggested that androgens and the cognate receptor (AR) may play important roles in the development and progression of prostate cancer. The AR is a transcription factor consisting of three major domains, i.e., N-terminal transactivation, middle DNA binding, and C-terminal steroid binding domains. Molecular events of androgen induced activation of the AR include conformation change, phosphorylation, acetylation, genomic DNA binding, and co-regulator recruiting. Many of these events can be manipulated in certain prostate cancer cells in favor of their progression. Dietary compounds and certain herbs have recently drawn a great deal of attention because of their relevance to development of several cancers including prostate cancer. We discuss in depth the findings from our and other laboratories of effects of dietary factors or herbs on the function of the AR and potential mechanisms on expression of the AR and AR regulated genes. We further discuss the potential implication of these dietary chemicals on prevention of development and progression of prostate cancer.

Androgens↗

PubMed2004

Methyl selenium metabolites decrease prostate-specific antigen expression by inducing protein degradation and suppressing androgen-stimulated transcription.

Prostate-specific antigen (PSA) is widely used clinically for prostate cancer diagnostics and as an indicator of therapeutic efficacy and recurrence. Several human chemoprevention trials are being conducted to validate the prostate cancer prevention efficacy of selenium and PSA is used in these trials as a biomarker of response. A better understanding of the effects of selenium metabolites on the kinetics of PSA turnover and secretion in prostate cancer cells treated with selenium at concentrations which are achievable physiologically will be important for interpreting the results of these trials. This study addresses whether the putative active anticancer selenium metabolite methylselenol or its precursor methylseleninic acid (MSeA) specifically inhibits PSA expression in the androgen-responsive LNCaP prostate cancer cell model. The results show that exposure to sub-apoptotic concentrations of MSeA and methylselenol inhibited PSA protein expression and secretion, whereas sodium selenite and selenomethionine lacked inhibitory effect. The inhibition was detectable at 3 h of exposure and required a threshold level of MSeA to sustain. Turnover experiments showed that MSeA caused rapid PSA degradation, which was partially blocked by lysosomal inhibitors, but not by a proteasomal inhibitor. Furthermore, MSeA treatment reduced PSA mRNA level, down-regulated androgen receptor protein expression, and inhibited androgen-stimulated PSA promoter transcription. In summary, methylselenol or MSeA specifically and rapidly inhibited PSA expression through two mechanisms of action: inducing PSA protein degradation and suppressing androgen-stimulated PSA transcription. These findings may have important mechanistic implications for the prostate specific cancer chemopreventive action of selenium.

Androgens↗

PubMed2003

Transcriptional silencing of zinc finger protein 185 identified by expression profiling is associated with prostate cancer progression.

We profiled the expression of genes in benign and untreated human prostate cancer tissues using oligonucleotide microarrays. We report here 50 genes with distinct expression patterns in metastatic and confined tumors (Gleason score 6 and 9; lymph node invasive and noninvasive). Validation of expression profiles of 6 genes by quantitative PCR revealed a strong inverse correlation in the expression of zinc finger protein 185 (ZNF185), bullous pemphigoid antigen gene (BPAG1), and prostate secretory protein (PSP94) with progression of prostate cancer. Treatment of prostate cancer cell lines with 5-aza-2'-deoxycytidine (5-Aza-CdR), an inhibitor of DNA methylation, restored ZNF185 expression levels. Moreover, methylation-specific PCR confirmed methylation of the 5'CpG islands of the ZNF185 gene in all of the metastatic tissues and 44% of the localized tumor tissues, as well as in the prostate cancer cell lines tested. Thus, transcriptional silencing of ZNF185 by methylation in prostate tumor tissues implicates the ZNF185 gene in prostate tumorigenesis.

Aged↗

PubMed2003

A phase II trial of green tea in the treatment of patients with androgen independent metastatic prostate carcinoma.

BACKGROUND: Recent laboratory and epidemiologic studies have suggested that green tea has antitumor effects in patients with prostate carcinoma. This Phase II trial explored green tea's antineoplastic effects in patients with androgen independent prostate carcinoma. METHODS: This study, which was conducted by the North Central Cancer Treatment Group, evaluated 42 patients who were asymptomatic and had manifested, progressive prostate specific antigen (PSA) elevation with hormone therapy. Continued use of luteinizing hormone-releasing hormone agonist was permitted; however, patients were ineligible if they had received other treatments for their disease in the preceding 4 weeks or if they had received a long-acting antiandrogen therapy in the preceding 6 weeks. Patients were instructed to take 6 grams of green tea per day orally in 6 divided doses. Each dose contained 100 calories and 46 mg of caffeine. Patients were monitored monthly for response and toxicity. RESULTS: Tumor response, defined as a decline >/= 50% in the baseline PSA value, occurred in a single patient, or 2% of the cohort (95% confidence interval, 1-14%). This one response was not sustained beyond 2 months. At the end of the first month, the median change in the PSA value from baseline for the cohort increased by 43%. Green tea toxicity, usually Grade 1 or 2, occurred in 69% of patients and included nausea, emesis, insomnia, fatigue, diarrhea, abdominal pain, and confusion. However, six episodes of Grade 3 toxicity and one episode of Grade 4 toxicity also occurred, with the latter manifesting as severe confusion. CONCLUSIONS: Green tea carries limited antineoplastic activity, as defined by a decline in PSA levels, among patients with androgen independent prostate carcinoma.

Aged↗

PubMed2003

Effects of vitamin C on androgen receptor mediated actions in human prostate adenocarcinoma cell line LAPC-4.

OBJECTIVES: To examine the effects of vitamin C (VC) on androgen receptor (AR)-mediated functions in a human prostate cancer cell line, Los Angeles prostate cancer (LAPC-4). VC is an essential dietary substance in the maintenance and preservation of vital functions in humans. However, the role of VC in prostate cancer remains to be elucidated. METHODS: Cell proliferation and the expression of two well-known androgen regulated proteins, prostate-specific antigen and human glandular kallikrein-2, were studied in the presence of VC. RESULTS: In the presence of androgen and VC, both cell growth and the expression of prostate-specific antigen and human glandular kallikrein-2 proteins were decreased. Moreover, AR-mediated transcription activity of the prostate-specific antigen gene was suppressed with VC, similar to the phenomenon observed when cells were treated with hydrogen peroxide. These effects were reversed with catalase. However, additional studies did not reveal changes in the expression level of AR protein or its androgen-binding activity with the addition of VC. CONCLUSIONS: The results of our study suggest that the pro-oxidant property of VC might be one of the mechanisms by which it modulates AR-mediated function in LAPC-4 cells.

Adenocarcinoma↗

PubMed2003

The cyclooxygenase 2-specific nonsteroidal anti-inflammatory drugs celecoxib and nimesulide inhibit androgen receptor activity via induction of c-Jun in prostate cancer cells.

Nonsteroidal anti-inflammatory drugs (NSAIDs) play potential roles in cancer chemoprevention. In this study, we investigated the effects of NSAIDs on androgen receptor (AR)-mediated functions in prostate cancer cells. We found that two cyclooxygenase 2-specific NSAIDs, celecoxib and nimesulide, dramatically reduced the expression of androgen-inducible genes, such as prostate-specific antigen, hK2, and the FK506-binding protein 51 (FKBP51). We demonstrated that both NSAIDs repressed AR-mediated activation of prostate-specific antigen and hK2 promoter activity as well as AR protein expression. Finally, our findings suggested that overexpressed c-Jun by the NSAIDs not only inhibited the function of AR but also directly repressed AR expression at the transcription level. Our findings provide a strong rationale for celecoxib and nimesulide as potential agents for prostate cancer prevention and/or treatment.

Androgen Receptor Antagonists↗

PubMed2003

Polymorphisms of prostate-specific antigen gene promoter: determination from cord blood collected on filter paper.

Recent studies have shown that a single nucleotide polymorphism of A/G substitution in the androgen response element-1 (ARE-1) of the promoter for the prostate-specific antigen gene is a biomarker of prostate cancer. Portugese men with prostate cancer have a high percentage (43%) of the AA polymorphism of the gene (41% AG, 16% GG), whereas healthy Japanese men have a much lower rate (5%) of the AA polymorphism, (31% AG, 64% GG). The goal of the present study was to see whether or not the Chinese also have a low rate of the AA polymorphism. This study used 94 specimens of cord blood that were the leftover waste of cord blood banking. The samples were collected from Chinese infants onto filter paper, dried, and shipped to Rochester, MN, USA, for PCR amplification and analysis. The observed rate of the AA polymorphism in the samples was very low (5%), with 26% AG, 69% GG. The low incidence of AA polymorphism appears to be a trait of Asians that may reduce their risk of prostate cancer.

Adenine↗

PubMed2002

Effect of geldanamycin on androgen receptor function and stability.

In the ligand-binding inactive state, the steroid receptor heterocomplex contains Hsp90, Hsp70, high-molecular weight immunophilins, and other proteins. Hsp90 acts in association with co-chaperones to maintain the native state of the receptor within the cells. It was reported earlier that Hsp90 might not be as important for the androgen receptor (AR) activity as for the glucocorticoid receptor (GR) and the progesterone receptor (PR) activities. We used the Hsp90 inhibitor geldanamycin (GA) to explore the role of Hsp90 in the function of the AR heterocomplex. GA selectively binds to Hsp90 and inhibits its activity, leading to the loss of steroid receptor activity, and frequently, its degradation. In our study, LNCaP prostate cancer cells were treated with GA for 30 minutes or 24 hours, in the presence of mibolerone, a synthetic androgen. GA reduced the androgen-induced AR protein levels to 15% after 24 hours of treatment. Several androgen up-regulated genes, including immunophilin FKBP51 and prostate specific antigen (PSA), were reduced by GA treatment. In cells treated with GA after transfection with a PSA promoter or an androgen response element-driven reporter gene, AR-mediated transactivation of reporter gene expression was reversibly inhibited by GA. Loss of androgen-binding ability and AR levels was attributed to reduced transcription of AR-regulated gene expression. Degradation rate of 35S-labeled AR was significantly increased by GA in the presence or absence of mibolerone. GA induced the degradation of AR through the proteasomal pathway. AR in cells treated with proteasomal inhibitor lactacystin, was insoluble in Nonidet P-40 (NP40)-based buffer and could not restore the androgen-binding ability. We report here that GA treatment disrupted both hormone-binding activity and receptor protein stability, resulting in a dramatic loss of androgen-induced gene activation. These results show that Hsp90 activity is important for both the chaperone-mediated folding of the AR into a high-affinity ligand-binding conformation and the functional activity of the AR.

Antibiotics, Antineoplastic↗

PubMed2002

The expression of a variant prostate-specific antigen in human prostate.

Although a splicing variant of prostate specific antigen (PSA-v) mRNA has been described previously, whether its protein (PSA-v or PSA-related protein 1, i.e., PSA-RP1) is actually expressed in human prostate cells remains elusive. We report that PSA-v protein is expressed in prostatic epithelia of both cancerous and benign tissues. Also, secreted PSA-v can be detected in the medium of a prostate cancer (PCa) cell line. Consistently, PSA-v mRNA is exclusively expressed in benign luminal epithelia and cancer cells of the prostate by in situ hybridization. Northern analysis of a cohort of 51 pairs of RNA samples from microdissected tissues showed that PSA-v mRNA levels remained constant in both benign and cancerous tissues, whereas PSA levels declined in cancerous areas. Our result suggests that it would be feasible to develop proper immunoassays for PSA-v to test whether PSA-v could have some clinical utility.

Aged↗