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)

The effects of androgens, antiandrogens, and other steroid hormones on growth of the human prostate cancer cell line LNCaP were studied. Despite the absence of receptors for progesterone and estradiol, the growth rate of the androgen responsive LNCaP-FGC cells increased when cultured in the presence of either estrogens or progestagens. In addition, most antiandrogens were also growth stimulators. This aberrant response was due to a threonine to alanine substitution at amino acid position 868 in the steroid binding domain of the androgen receptor (AR). Only the antiandrogen ICI 176,334 could block transcription and cell growth by the mutant receptor. By immunoprecipitation of the AR from LNCaP cells with the specific antibody F39.4.1 and Western blotting, three types of heat-shock proteins co-precipitated: hsp90, hsp70 and hsp56. This co-isolation could be prevented by pre-incubating the cells with androgens or with the antiandrogen hydroxyflutamide. Only the antiandrogen ICI 176,334 could block the effect of androgens on complex dissociation and prevent tight nuclear binding of the AR. Hydroxyflutamide could only inhibit tight nuclear binding of the wild-type AR. Therefore, in LNCaP cells the mutation in the steroid binding domain of the AR prevents a blockade of receptor function by most antiandrogens, but not by ICI 176,334, probably because of a different mechanism by which this compound blocks receptor function.
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PMID:Studies on the human prostatic cancer cell line LNCaP. 804 98

Prostatic tissue specimens derived from transurethral resections of patients with metastatic prostate cancer were analyzed for genetic alterations in the hormone-binding domain of the androgen receptor (AR) gene. Direct sequencing of the polymerase chain reaction-derived DNAs of 6 of 24 specimens revealed a codon 877 mutation (ACT-->GCT, Thr-->Ala) in the hormone-binding domain of the AR gene. This same AR mutation has been reported previously in a metastatic prostate cancer cell line, LNCaP, where this mutation confers upon the AR an altered ligand-binding specificity which is stimulated by estrogens, progestagens, and antiandrogens. It is possible that analogous to an activated/altered growth factor receptor oncogene, codon 877 mutant AR with altered ligand binding may provide a selective growth advantage in the genesis of a subset of advanced prostate cancer. Although estrogens are used infrequently, antiandrogens are used increasingly in hormonal therapy for patients with advanced prostate cancer. The stimulatory effect of these therapeutic agents on the codon 877 mutant AR further suggests that this frequently observed AR mutation may contribute to the treatment refractory disease.
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PMID:Frequent detection of codon 877 mutation in the androgen receptor gene in advanced prostate cancers. 818 68

The plasminogen activator urokinase (u-PA) mediates proteolysis by a variety of human tumor cells. Competitive displacement of u-PA from cellular binding sites results in decreased proteolysis in vitro, suggesting that the cell surface is the preferred site for u-PA-mediated protein degradation. We studied the effect of u-PA receptor blockade on the metastatic capacity of human PC3 prostate carcinoma cells, using transfectants which expressed chloramphenicol acetyl-transferase (CAT). Eight weeks after subcutaneous inoculation of these cells into nude mice, CAT activity was detected in regional lymph nodes, femurs, lungs, and brain, thereby mimicking the organ tropism observed for naturally occurring metastases of prostate cancer. In a second transfection, CAT-expressing PC3 cells received cDNA encoding a mutant u-PA (Ser356-->Ala) which lacks enzymatic activity but which retains full receptor binding affinity. Three mutant u-PA expressors, each with < 5% of wild-type cell-associated u-PA activity, were compared in vivo with independently derived controls. Primary tumor growth was similar in each group of animals and all tumors expressed comparable CAT activity. In contrast, metastasis (as assessed by CAT activity) was markedly inhibited when cell surface u-PA activity was blocked. Levels of CAT activity were reduced by a factor of > 300 in regional lymph nodes, 40-100 in brain tissue, and 10-20 in lung tissue. Metastatic capacity was inhibited similarly when animals were given intermittent intraperitoneal injections of a u-PA/IgG fusion protein capable of displacing u-PA activity from the tumor cell surface. Our results indicate that cell surface u-PA activity is essential to the metastatic process. In addition, the assay system employed in these experiments may be generally useful in testing other therapeutic modalities to limit the spread of primary tumors.
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PMID:Prevention of metastasis by inhibition of the urokinase receptor. 838 64

The growth of prostate cancer is androgen responsive, and androgen receptor (AR) is thought to play an important role in the development of this cancer. Recently, some reports demonstrated that AR gene mutations were detected in human prostate cancer tissues. We have previously reported that one of eight endocrine therapy-resistant prostate cancer cases showed AR gene mutation [Suzuki et al: J Steroid Biochem Mol Biol 46:759-765, 1993]. To further investigate structural abnormality of the AR in a large number of human prostate cancers, exons B-H encoding DNA-and hormone-binding domains were examined by single-strand conformation polymorphism analysis of polymerase chain reaction products and direct sequencing. Tissues surgically removed from 30 cases of stage B or C prostate cancer and from 22 cases of endocrine therapy-resistant cancers obtained at autopsy were used in the study. Three out of 22 cancer death cases (14%) revealed AR gene mutations, one of which contained two different mutations-exon D in cancerous prostate and exon H in metastatic tissues. In the other two cases, AR gene mutations in exon H were found in metastatic tissues. All three cases in metastatic tissues showed the same mutation at codon 877 (877Thr-->Ala). In stage B or C cancer tissues and the other cancer death samples, no AR mutation was detected. The mutation in exon H was identical to that reported in a human prostate cancer cell line, LNCaP. These results indicate that AR gene mutation scarcely occurs in the early stage of prostate cancer and that the mutation is found in relation to endocrine therapy resistance. Two patients with an AR gene mutation at codon 877 revealed a remarkable fall in prostate-specific antigen after withdrawal of antiandrogen. Data on the other case were not available. These results indicate that a codon 877 mutation in the AR gene in advanced prostate cancer evokes the antiandrogen withdrawal syndrome. To our knowledge, this report is the first description of relationship between an AR mutation at codon 877 and the antiandrogen withdrawal syndrome.
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PMID:Codon 877 mutation in the androgen receptor gene in advanced prostate cancer: relation to antiandrogen withdrawal syndrome. 882 83

Progression of prostate cancer during endocrine therapy is a major clinical problem, the molecular mechanisms of which remain poorly understood. Amplification of the androgen receptor (AR) gene was recently described in recurrent prostate carcinomas from patients who had failed androgen deprivation therapy. To evaluate the hypothesis that amplification of the AR gene is a cause for the failure of androgen deprivation therapy in prostate cancer, we studied whether AR amplification leads to gene overexpression, whether the amplified AR gene is structurally intact, and whether tumors with AR amplification have distinct biological and clinical characteristics. Tumor specimens were collected from 54 prostate cancer patients at the time of a local recurrence following therapy failure. In 26 cases, paired primary tumor specimens from the same patients prior to therapy were also available. Fifteen (28%) of the recurrent therapy-resistant tumors, but none of the untreated primary tumors, contained AR gene amplification as determined by fluorescence in situ hybridization. According to single-stranded conformation polymorphism analysis, the AR gene was wild type in all but one of the 13 AR amplified cases studied. In one tumor, a presumed mutation in the hormone-binding domain at codon 674 leading to a Gly --> Ala substitution was found, but functional studies indicated that this mutation did not change the transactivational properties of the receptor. AR amplification was associated with a substantially increased level of mRNA expression of the gene by in situ hybridization. Clinicopathological correlations indicated that AR amplification was most likely to occur in tumors that had initially responded well to endocrine therapy and whose response duration was more than 12 months. Tumors that recurred earlier or those that showed no initial therapy response did not contain AR amplification. The median survival time after recurrence was two times longer for patients with AR amplification in comparison to those with no amplification (P = 0.03, Willcoxon-Breslow test). In conclusion, failure of conventional androgen deprivation therapy in prostate cancer may be caused by a clonal expansion of tumor cells that are able to continue androgen-dependent growth despite of the low concentrations of serum androgens. Amplification and the increased expression of a wild-type AR gene may play a key role in this process.
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PMID:Androgen receptor gene amplification: a possible molecular mechanism for androgen deprivation therapy failure in prostate cancer. 900 May 75

The tumor suppressor gene p16/MTS1, located on chromosome 9p21, is a cell cycle regulatory gene which is frequently altered in human cancers. The role of this gene in prostate cancer is unknown. To determine the frequency of deletions and point mutations of p16/MTS1 in human prostate cancer, we examined 18 cancer and matched benign and hyperplastic tissue specimens. Deletions of p16/MTS1 were detected by semi-quantitative multiplex polymerase chain reaction in which a portion of exon 2 of the p16/MTS1 gene and a control marker, the glyceraldehyde 3-phosphate dehydrogenase gene, were amplified simultaneously. 'Cold' single-stranded conformational polymorphism (SSCP) analysis was performed to examine exons 1 and 2 of the p16/MTS1 gene for point mutations. Our data indicate no evidence for intragenic homozygous deletion in the prostate tumors. One prostate tumor and matched benign tissue showed mobility shifts. Direct DNA sequencing of the SSCP positive samples showed a G --> A transition in codon 140 which would result in an amino acid change from alanine to threonine. Our results indicate that deletions and point mutations in the p16/MTS1 gene are rare and do not play a major role in human prostate carcinogenesis.
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PMID:Absence of p16/MTS1 gene mutations in human prostate cancer. 900 95

To identify whether alterations of the p16 tumor suppressor gene are a common event in localized prostate cancer, we examined the frequency of p16 gene mutations in 30 primary tumors. Only two tumors demonstrated altered single-strand conformation polymorphism patterns for exon 2 of p16. In both cases, sequencing revealed a missense at codon 148, a G-->A transition that resulted in the replacement of the alanine by threonine. Polymerase chain reaction-single-strand conformation polymorphism analysis of matched blood samples revealed the same abnormal band shifts as the tumor samples, suggesting that these base changes are polymorphic. In addition, transcriptional inactivation by means of CpG island methylation has also been reported as a possible means of p16 gene inactivation. To address this point, we determined the pattern of DNA methylation at the Smal site for 21 of 30 samples for which DNA was available. Only one sample had an altered methylation pattern at the Smal site downstream of exon 1 of the p16 gene, which is outside the CpG island and is not normally associated with transcriptional inactivation. However, two samples did have deletions proximal to or within the p16 gene. These results indicate that mutations in p16 may not be a dominant pathway for p16 loss of function or that inactivation of p16 by DNA methylation may not be necessary for the transformation and progression of prostate cancer.
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PMID:Analysis of the p16 tumor suppressor gene in early-stage prostate cancer. 953 47

Taxoids and other microtubule-damaging drugs are known to induce Bcl2 phosphorylation at the G2-M phase of the cell cycle, with concomitant apoptosis in malignant cells derived from a variety of human malignancies, including leukemia, lymphoma, and breast and prostate cancer. We have investigated the ability of another antineoplastic drug, dolastatin 10, in inducing Bcl2 phosphorylation and apoptosis. We also investigated the effects of a phosphatase inhibitor okadaic acid in the regulation of Bcl2 phosphorylation, cell cycle arrest, and programmed cell death. Moreover, site-directed mutagenesis studies were performed to determine the specific serine residue(s) responsible for drug-induced Bcl2 phosphorylation. Our results indicate that these antimicrotubule agents or okadaic acid can induce posttranslational modification (phosphorylation) of Bcl2 protein at multiple serine residues. Interestingly, mutation of a serine residue at position 70 to alanine can significantly decrease drug-induced posttranslational modification (phosphorylation) of Bcl2 protein. Apparently, Ser70 seems to be a critical site for drug-induced posttranslational modification (phosphorylation) of the Bcl2 protein.
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PMID:Serine-70 is one of the critical sites for drug-induced Bcl2 phosphorylation in cancer cells. 956 69

The chemotherapeutic agent paclitaxel disrupts microtubule dynamics causing mitotic arrest, which leads to cell death. However, in paclitaxel-resistant tumor cells, treatment with paclitaxel induces abnormal progression through prophase resulting in a multimininucleated phenotype. Multimininucleation and subsequent polyploidization have been correlated with paclitaxel resistance. Paclitaxel treatment of HeLa cells resulted in cell death via typical activation of the apoptotic machinery, whereas treatment of the relative paclitaxel-resistant prostate cancer cell line PC-3 induced an attenuated caspase activation and multimininucleation. The multimininucleated phenotype could be mimicked in HeLa cells treated with paclitaxel and benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (z-VAD-fmk), a peptide caspase inhibitor. Interestingly, we observed no discernible difference in the pattern of cdc-2 kinase activation or phosphorylation of bcl-2-like proteins in PC-3 and HeLa cells treated with paclitaxel, which demonstrated that these molecules could not be used as indicators for the degree of caspase activation. In this study, we establish a connection between relative paclitaxel resistance, caspase attenuation/inhibition, and the multimininucleated phenotype.
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PMID:Paclitaxel-associated multimininucleation is permitted by the inhibition of caspase activation: a potential early step in drug resistance. 978 20

We studied the molecular mechanisms of apoptosis in the prostate cancer cell line LNCaP and whether overexpression of caspase activity could force this cell line to undergo apoptosis. The inhibitor of phosphomevalonate decarboxylase, sodium phenylacetate, and the protein kinase inhibitor staurosporine induced (a) release of cytochrome c from the mitochondria to the cytosol; (b) reduction in mitochondrial transmembrane potential; (c) proteolytic processing of caspase-3 and -7 but not -2; (d) cleavage of the DEVD substrate and the death substrates poly(ADP-ribose) polymerase and DNA fragmentation factor; and (e) apoptosis. The panspecific inhibitor of caspase activation N-benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone (z-VAD-FMK) prevented all of these events except release of mitochondrial cytochrome c into the cytosol. None of these apoptotic signaling events were elicited by staurosporine or sodium phenylacetate treatment of LNCaP-Bcl-2 cells that overexpress the oncoprotein Bcl-2. Because caspase-7 is activated in every model of apoptosis that we have characterized thus far, we wished to learn whether overexpression of this protease could directly cause apoptosis of LNCaP cells. By using a replication-defective adenovirus, overexpression of caspase-7 protein in both LNCaP and LNCaP-Bcl-2 cells was accompanied by induction of cleavage of the DEVD substrate and TUNEL. These studies have demonstrated that caspase-7 and -3 are critical mediators of apoptosis in LNCaP cells. Caspase-7 was proteolytically activated in every model of apoptosis that we have developed, and the overexpression of it induced apoptosis of LNCaP and LNCaP-Bcl-2 cells. Thus, adenoviral-mediated transfer of caspase-7 may offer a new effective approach for the treatment of prostate cancer.
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PMID:Signaling pathway activated during apoptosis of the prostate cancer cell line LNCaP: overexpression of caspase-7 as a new gene therapy strategy for prostate cancer. 992 51


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