Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

mRNA differential display polymerase chain reaction analysis was used to screen systematically for novel androgen-regulated genes in the human prostatic adenocarcinoma cell line LNCaP. A 232 bp PCR fragment was found to be consistently down-regulated by the synthetic androgen R1881. Sequencing revealed complete identity with the human homologue of mouse Paternally expressed gene 3 (Peg3), an imprinted gene that plays an important role as a downstream mediator of the effects of tumor necrosis factor (TNF). The down-regulation of Peg3 mRNA by androgens was confirmed by Northern blot hybridization. The effect proved time and dose dependent with maximal repression (3.5-fold) after 24 h of treatment with 10(-8) M R1881. The steroid specificity of Peg3 mRNA regulation reflected the aberrant ligand specificity of the mutated androgen receptor in LNCaP cells, supporting the involvement of the androgen receptor in the repression process. Basal expression of Peg3 mRNA was almost completely abolished by the protein synthesis inhibitor cycloheximide. Experiments with Actinomycin D suggested that androgens act at a transcriptional level rather than by changing the stability of Peg3 mRNA. Comparison of the expression of Peg3 mRNA in 50 different human tissues revealed ubiquitous expression, but low levels in the prostate. The highest levels were observed in endocrine tissues such as ovary, placenta, adrenal and pituitary. High levels were also noted in various parts of the brain. No detectable levels of Peg3 mRNA were observed in two other androgen receptor-positive prostate tumor cell lines (MDA PCa-2a and -2b), and in the poorly differentiated and androgen receptor-negative prostate tumor lines PC-3 and DU-145. It is concluded that both androgens and loss of differentiation may affect the expression of Peg3, a mediator of the effects of TNF. Further experiments will be required to explore whether these changes affect the responsiveness of prostate tumor cells to TNF.
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PMID:Androgens down-regulate the expression of the human homologue of paternally expressed gene-3 in the prostatic adenocarcinoma cell line LNCaP. 1058 Aug 40

Trans-resveratrol, a polyphenol present in red wines and various human foods, inhibited the proliferation of LNCaP cells and the expression of a prostate specific gene, PSA. A 4-day treatment with resveratrol reduced the levels of intracellular and secreted PSA by approximately 80%, as compared to controls. To test whether this decrease was coordinated with changes in AR expression, levels of AR were assayed by Western blot analysis, using the cognate antibody, or by binding with the radioactive ligand methyltrienolone [3H]R1881. With either assay, little or no change in AR expression could be detected between control and resveratrol-treated cells. Thus, it would appear that the prostate tumor marker PSA is down regulated by resveratrol, by a mechanism independent of changes in AR.
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PMID:Grape-derived chemopreventive agent resveratrol decreases prostate-specific antigen (PSA) expression in LNCaP cells by an androgen receptor (AR)-independent mechanism. 1076 59

Biologic effects of androgen on target cells are mediated in part by transcriptional regulation of androgen-regulated genes (ARGs) by androgen receptor. Using serial analysis of gene expression (SAGE), we have identified a comprehensive repertoire of ARGs in LNCaP cells. One of the SAGE-derived tags exhibiting homology to an expressed sequence tag was maximally induced in response to synthetic androgen R1881 treatment. The open reading frame of the androgen-induced RNA (PMEPA1) was characterized as a 759-bp nucleotide sequence coding for a 252-amino-acid protein. The analysis of PMEPA1 protein sequence indicated the existence of a type Ib transmembrane domain between residues 9 and 25. Analysis of multiple-tissue Northern blots revealed the highest level of PMEPA1 expression in prostate tissue. PMEPA1 expression was predominately detected in glandular epithelial cells of prostate by in situ hybridization analysis. The expression of PMEPA1 in LNCaP cells was induced by androgen in a time- and dose-specific manner. Evaluation of PMEPA1 expression in androgen-dependent/independent tumors of the CWR22 xenograft model revealed that PMEPA1 was overexpressed in three of four androgen-independent tumor tissues. These observations define PMEPA1 as a novel androgen-regulated gene exhibiting abundant expression in prostate tissue. The increased expression of PMEPA1 in relapsed tumors of the CWR22 model suggests activation of androgen signaling in hormone refractory disease. PMEPA1, along with other highly androgen-induced prostate-specific genes, has potential to serve as an androgen signaling read-out biomarker in prostate tissue.
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PMID:A novel androgen-regulated gene, PMEPA1, located on chromosome 20q13 exhibits high level expression in prostate. 1087 80

Androgen-induced calcium fluxes and gap junctional intercellular communication (GJIC) were studied in three different cell types. A transient (2-3 min duration) increase in intracellular calcium levels was observed within 20-30 sec of androgen addition, which was followed by a plateau phase with steroid concentrations higher than 1 nM. The kinetics of the calcium responses were similar in immature rat Sertoli cells, which contain normal nuclear receptors; the human prostatic tumor cell line, LNCaP, which contains a mutated nuclear receptor; and the human prostatic cell line, PC3, which does not contain a nuclear receptor. The human A431 tumor cell line did not respond to androgens. Concentrations of testosterone and the synthetic androgen, R1881, between 1-1000 pM induced transient calcium increases with ED(50) values near 1 pM and 1 nM, whereas dihydrotestosterone (DHT) was not active at these concentrations. At concentrations higher than 1 nM, testosterone, R1881, and DHT were equipotent in stimulating an increase in calcium that lasted for more than 10 min, with ED(50) values between 5 and 20 nM. Testosterone covalently bound to albumin was also active, whereas 11 related androstane compounds as well as progesterone and estradiol-17beta were inactive at 1000 nM. The calcium response induced by the three androgens (10 nM) was abolished in all cell types by hydroxyflutamide (1000 nM) and finasteride (1000 nM), but not by cyproterone acetate (1000 nM). The calcium response was also abolished in the absence of extracellular calcium and strongly inhibited by the presence of verapamil. Exposure of the responsive cells to brief (150-sec) pulses of androgens generated calcium responses that were similar to those after continuous exposure. After exposure of Sertoli cells for only 30 sec to 100 nM testosterone, the calcium response lasted for at least 50 min. Although nuclear binding of androgens could be demonstrated, there was no evidence for tight binding to the plasma membrane under similar conditions. When protein synthesis was inhibited, an enhancement of GJIC between rat Sertoli cells, but not between LNCaP cells or PC3 cells, was observed within 15 min of the addition of 10 nM testosterone. Because nuclear androgens are not present in PC3 cells and many functional properties of the responsive system are different from the nuclear receptor in all three cell types, we postulate the existence of an alternative cell surface receptor system with biphasic response characteristics (high and low affinity). The calcium signals are probably coupled to the regulation of gap junctional efficiency between Sertoli cells. The low-affinity receptors may convey complementary androgen signals at elevated local levels such as in the testis, when nuclear receptors are (over)saturated.
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PMID:Rapid androgen actions on calcium signaling in rat sertoli cells and two human prostatic cell lines: similar biphasic responses between 1 picomolar and 100 nanomolar concentrations. 1095 15

We have found that in addition to being potent inhibitors of 17alpha-hydroxylase/C17,20-lyase and/or 5alpha-reductase, some of our novel androgen synthesis inhibitors also interact with the mutated androgen receptor (AR) expressed in LNCaP prostate cancer cells and the wild-type AR expressed in hormone-dependent prostatic carcinomas. The effects of these compounds on the proliferation of hormone-dependent human prostatic cancer cells were determined in vitro and in vivo. L-2 and L-10 are delta4-3-one-pregnane derivatives. L-35 and L-37 are delta5-3beta-ol-androstane derivatives, and L-36 and L-39 are delta4-3-one-androstane-derived compounds. L-2, L-10, and L-36 (L-36 at low concentrations) stimulated the growth of LNCaP cells, indicating that they were interacting agonistically with the mutated AR expressed in LNCaP cells. L-35, L-37, and L-39 acted as LNCaP AR antagonists. To determine whether the growth modulatory effects of our novel compounds were specific for the mutated LNCaP AR, competitive binding studies were performed with LNCaP cells and PC-3 cells stably transfected with the wild-type AR (designated PC-3AR). Regardless of AR receptor type, all of our novel compounds were effective at preventing binding of the synthetic androgen methyl-trienolone[17alpha-methyl-(3H)-R1881 to both the LNCaP AR and the wildtype AR. L-36, L-37, and L-39 (5.0 microM) prevented binding by >90%, whereas L-35 inhibited binding by 30%. To determine whether the compounds were acting as agonists or antagonists, LNCaP cells and PC-3AR cells were transfected with the pMAMneoLUC reporter gene. When luciferase activity was induced by dihydrotestosterone, all of the compounds were found to be potent inhibitors of transcriptional activity, and the pattern of inhibition was similar for both receptor types. However, L-2, L-10, and L-36 were determined to be AR agonists, and L-35, L-37, and L-39 were wild-type AR antagonists. When tested in vivo, L-39 was the only AR antagonist that proved to be effective at inhibiting the growth of LNCaP prostate tumor growth. L-39 slowed tumor growth rate in LNCaP tumors grown in male SCID mice to the same level as orchidectomy, significantly reduced tumor weights (P < 0.05), significantly lowered serum levels of prostate-specific antigen (P < 0.02), and significanty lowered serum levels of testosterone (P < 0.05). L-39 also proved to be effective when tested against the PC-82 prostate cancer xenograft that expresses wild-type AR. These results show that some of our compounds initially developed to be inhibitors of androgen synthesis also interact with the human AR and modulate the proliferation of hormone-dependent prostatic cancer cells. Therefore, compounds such as L-39, which have multifunctional activities, hold promise for the treatment of androgen-dependent prostate tumors.
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PMID:Antiandrogenic effects of novel androgen synthesis inhibitors on hormone-dependent prostate cancer. 1111 46

Tissue-specific transcriptional regulatory elements can increase the safety of gene therapy vectors. Unlike prostate-specific antigen (PSA/hK3), whose expression displays an inverse correlation with prostate cancer grade and stage, human glandular kallikrein 2 (hK2) is upregulated in higher grade and stage disease. Therefore, our goal was to develop a strong and prostate-specific hK2-based promoter for targeted gene therapy. We identified the minimum "full-strength" hK2 enhancer and built transcriptional regulatory elements composed of multiple tandem copies of this 1.2-kb enhancer, fused to the hK2 minimal promoter. Relative to the weak induction of the minimal hK2 promoter by androgen analog (R1881) in androgen receptor (AR)-positive LNCaP cells, transcriptional activity was increased by 25-, 44-, 81-, and 114-fold when one to four enhancers were spliced to the hK2 promoter, respectively. In contrast, the enhancer/promoter elements were inactive in the AR(-) prostate cancer line PC-3 and in a panel of nonprostate lines, including 293, U87, MCF-7, HuH-7, and HeLa cells. Furthermore, we generated a recombinant adenovirus, ADV.hK2-E3/P-EGFP, expressing enhanced green fluorescent protein (EGFP) under the control of the hK2 triplicate enhancer/promoter, and compared its properties with ADV.CMV-EGFP expressing EGFP under the control of the cytomegalovirus (CMV) enhancer/promoter. Unlike the CMV promoter, the hK2-E3/P promoter was at least 100-fold inducible by R1881 in the adenoviral backbone. Compared with in situ injection of subcutaneous LNCaP tumors with ADV.CMV-EGFP, which led to detectable EGFP expression in tumor, liver, and brain tissue, ADV.hK2-E3/P-EGFP injection led to robust but tumor-restricted EGFP expression. These results suggest that the hk2 multienhancer/promoter should be a powerful novel reagent for safer targeted gene therapy of prostate cancer.
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PMID:Robust prostate-specific expression for targeted gene therapy based on the human kallikrein 2 promoter. 1126 87

The androgen receptor (AR) is highly expressed in androgen-dependent and recurrent prostate cancer (CaP) suggesting it has a role in the growth and progression of CaP. Previously proposed mechanisms for AR reactivation in recurrent CaP include altered growth factor signaling leading to protein phosphorylation and AR mutations that broaden ligand specificity. To further establish a role for AR in recurrent CaP, we compared several properties of AR in relation to the growth response to low levels of androgens in model systems of androgen-dependent and recurrent CaP. AR from all of the tumors and cell lines bound [3H]R1881 with similar high affinity (mean Kd, 0.12 nM). In the absence of androgen, AR in androgen-dependent LNCaP cells was unstable with a degradation half-time (t(1/2)) of 3 h at 37 degrees C. In contrast, AR was 2-4 times more stable in recurrent CWR22 tumors (t(1/2), >12 h) and CWR-R1 or LNCaP-C4-2 cell lines (t(1/2), 6-7 h) derived from recurrent prostate tumors. In the recurrent CWR22 tumor and its CWR-R1 cell line grown in the absence of androgen, AR immunostaining was entirely nuclear, whereas under the same conditions AR in LNCaP-C4-2 and LNCaP cells was predominantly nuclear but was also detected in the cytoplasm. High level expression, increased stability, and nuclear localization of AR in recurrent tumor cells were associated with an increased sensitivity to the growth-promoting effects of dihydrotestosterone in the femtomolar range. The concentration of dihydrotestosterone required for growth stimulation in CWR-R1 and LNCaP-C4-2 cells was four orders of magnitude lower than that required for androgen-dependent LNCaP cells. The results suggest that AR is transcriptionally active in recurrent CaP and can increase cell proliferation at the low circulating levels of androgen reported in castrated men.
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PMID:Androgen receptor stabilization in recurrent prostate cancer is associated with hypersensitivity to low androgen. 1130 64

MUC1 mucin is transcriptionally regulated by estrogen, progesterone, and glucocorticoids. Our objective was to determine whether androgen receptor (AR) activation regulates expression of MUC1. The following breast and prostatic cell lines were phenotyped and grouped according to AR and MUC1 protein expression: 1) AR+MUC1 + [DAR17+19 (AR transfectants of DU-145), ZR-75-1, MDA-MB-453, and T47D]; 2) AR-MUC1 + [DZeo1 (AR-vector control), DU-145, BT20, MDA-MB-231, and MCF7]; 3) AR+MUC1 - (LNCaP and LNCaP-r). Cell proliferation was determined using the MTT assay in the presence of synthetic androgen R1881, 0.1 microM to 1 microM. Cell surface MUC1 expression was determined by flow cytometry in the presence or absence of oestradiol, medroxy progesterone acetate or R1881, with and without 4 hydroxy-flutamide (4-OH), a nonsteroidal AR antagonist. The functional significance of MUC1 expression was investigated with a cell-cell aggregation assay. Only AR+MUC1 + cell lines showed a significant increase in MUC1 expression with AR activation (P (range) =.01 to .0001), reversed in the presence of 4-OHF. Cell proliferation was unaffected. Increased expression of MUC1 was associated with a significant (P (range) = .002 to .001) reduction in cell-cell adhesion. To our knowledge, this is the first description of androgen-dependent regulation of MUC1 mucin. This is also functionally associated with decreased cell-cell adhesion, a recognised feature of progressive malignancy. These findings have important implications for physiological and pathological processes.
Neoplasia
PMID:Androgen-dependent regulation of human MUC1 mucin expression. 1192 95

Poly(ADP-ribose) polymerase (PARP) has strong affinity for DNA strand breaks and cycles on and off the DNA ends to allow DNA repair. A DNA-binding domain of PARP (PARP-DBD) acts as a dominant-negative mutant by binding to DNA strand breaks irreversibly and sensitizing mammalian cells to DNA-damaging agents. Therefore, expression of PARP-DBD in prostate carcinoma cells offers a strategy to achieve sensitization to genotoxic treatments. Toward this end, we developed recombinant plasmids expressing the PARP-DBD under the control of the 5'-flanking sequences of the human prostate-specific antigen (PSA) gene. Tissue specificity of PARP-DBD expression in human tumor cells was confirmed using the PSA-producing (LNCaP) and PSA-negative (PC-3) prostate cancer cells, as well as cells of nonprostate origin, Ewing's sarcoma (A4573 cells). LNCaP cells stably transfected with the PSA-regulated cDNA for PARP-DBD exhibit an androgen-dependent induction of PARP-DBD expression as determined by Western blotting, reverse transcription-PCR, and in situ immunofluorescence. Furthermore, we found that PARP-DBD sensitized LNCaP cells to DNA-damaging agents, such as ionizing radiation and etoposide. Androgen (R1881) -dependent stimulation of PARP-DBD expression resulted in a 2-fold growth inhibition in LNCaP cells as compared with controls, and an augmented apoptotic cell death in response to ionizing radiation or etoposide. Taken together, the plasmid vector developed in this study permits the expression of the human PARP-DBD in an androgen-inducible and PSA-dependent fashion, and sensitizes prostatic adenocarcinoma cells to DNA-damaging treatments. These results provide proof-of-principle for a novel therapeutic strategy for the treatment of prostate cancer.
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PMID:Gene therapy for prostate cancer by targeting poly(ADP-ribose) polymerase. 1246 Sep 2

Research into molecular and genetic mechanisms underlying prostate carcinogenesis would be greatly advanced by in vitro models of prostate tumors representing primary tumors. The generation of immortalized primary prostate cancer cells that will accurately reflect the in situ characteristics of malignant epithelium is greatly needed. We have successfully established a neoplastic immortalized human prostate epithelial (HPE) cell culture derived from a primary tumor. The RC-9 cells transduced through infection with a retrovirus vector expressing the E6 and E7 genes (E6E7) of human papilloma virus-16 (HPV-16) are currently growing well at passage 40, whereas RC-9 cells senesced at passage 7. RC-9/E6E7 cells exhibit epithelial morphology and high level of telomerase activity. More importantly, these immortalized cells produced tumors (SCID5038D) when inoculated into SCID mice. RC-9/E6E7 cells and SCID-5038D cells exhibit a high level of telomerase activity and androgen-responsiveness when treated with R1881. Expression of prostate specific antigen (PSA), androgen receptor (AR), prostate stem cell antigen (PSCA), an androgen-regulated prostate specific gene (NKX3.1), p16, cytokeratins 8, 15 and HPV-16 E6 gene was detected in both of these cells. RC-9/E6E7 and SCID5038D cells also showed growth inhibition when exposed to retinoic acid and transforming growth factor (TGF)-beta1, potent inhibitors of prostate epithelial cell growth. A number of chromosome alterations were observed including the loss of chromosomes 2p, 3p, 8p, 13, 14, 16, 17, 18, 21 and the gain of 7 and 20 in the tumor cell line (SCID5038D). These results demonstrate that this primary tumor-derived HPE cell line retained its neoplastic phenotypes and its prostate-specific markers and should allow studies to elucidate molecular and genetic alterations involved in prostate cancer. This is the first documented case of a malignant AR and PSA positive established human prostate cancer cell line from a primary tumor of a prostate cancer patient.
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PMID:A novel neoplastic primary tumor-derived human prostate epithelial cell line. 1273 99


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