Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0006142 (breast cancer)
 160,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The syntheses of new cycloalkyl- and cycloalkylalkyl-substituted 3-(4-aminophenyl)-piperidine-2,6-diones and their evaluation as aromatase inhibitors is described. Seven of the new compounds were more active in vitro than the cyclohexyl compound (CHAG), a former clinical candidate: cycloheptyl (1), cycloheptylmethyl (2), cyclohexylmethyl (3), cyclopentylmethyl (4), 1-adamantylmethyl (6), 2-cyclohexylethyl (7) and 2-cyclopentylethyl (8). Compound 3 was the most active, exceeding the potency of aminoglutethimide (AG) and CHAG by factors of 356 and 3, respectively, and reaching the activity of fadrozole. With the exception of 4, the other highly potent aromatase inhibitors were less active towards P450 scc compared with AG. Selected compounds showed only little inhibition of P450 18. In a QSAR study including analogous non-cyclic alkyl-substituted piperidinediones a linear relationship between logP and -logIC50 was found. Tested in vivo, compounds 1, 3, 4, 6 and 7 inhibited androgen-stimulated uterine growth in immature Sprague-Dawley rats as potently as CHAG. At a dose of 8.6 micromol/kg body wt compound 2 was superior to CHAG and thus might be a candidate for the treatment of breast cancer.
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PMID:Synthesis, evaluation and QSAR studies of highly potent aromatase inhibitors of the piperidinedione type. 1176 43

Oxford BioMedica is developing gene therapies for treating various forms of cancer. The therapies comprise the transfer of several anticancer genes at a time using a recombinant retrovirus approach based on the company's proprietary LTR Deleted Vector and Accelerated Vector Evolution technologies [238147]. MetXia-P450 is a gene therapy construct containing the cytochrome P450 gene CYP2B6, and is designed to be injected directly into tumors to convert them into 'drug factories'. This is achieved because CYP2B6 converts the inactive produg form cyclophosphamide into the active cytotoxic drug. MetXia-P450 is in phase I/II trials for breast cancer [339582].
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PMID:Technology evaluation: MetXia-P450, Oxford Biomedica. 1180 75

Polycyclic aromatic hydrocarbons (PAHs) and metals are often environmental cocontaminants, yet there have been relatively few studies of combined effects of PAHs and metals on cytochrome P450 (P450)-catalyzed metabolism. We examined the effects of NaAsO(2) in combination with benzo[a]pyrene (BAP) on CYP1A1 and CYP1B1 in T-47D human breast cancer cells by using estrogen metabolism as a probe of their activities. Exposure to BAP caused elevated rates of the 2- and 4-hydroxylation pathways of estrogen metabolism, indicating induction of both CYP1A1, an estradiol 2-hydroxylase, and CYP1B1, an estradiol 4-hydroxylase. BAP-induced metabolism peaked 9 to 16 h after exposure and returned to near-basal levels by 48 h. Concentration-response studies showed maximal induction of the 2- and 4-hydroxylation pathways at 3 microM BAP; higher levels caused reduced rates of metabolism due to inhibition of CYP1A1 and CYP1B1. NaAsO(2) caused pronounced decreases in the induction of CYP1A1 and CYP1B1 by 3 microM BAP because cotreatment with 10 microM NaAsO(2) inhibited the rates of the 2- and 4-hydroxylation pathways by 86 and 92%, respectively. Western immunoblots showed diminished levels of BAP-induced CYP1A1 by coexposure to NaAsO(2). The levels of the CYP1A1 and CYP1B1 mRNAs induced by BAP were not significantly affected by coexposure to NaAsO(2); however, heme oxygenase 1 mRNA levels were markedly induced by coexposure to BAP and NaAsO(2). These results indicate a post-transcriptional inhibitory effect of arsenite on the expression of CYP1A1 and CYP1B1 in T-47D cells, possibly resulting from reduced heme availability.
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PMID:Induction of CYP1A1 and CYP1B1 in T-47D human breast cancer cells by benzo[a]pyrene is diminished by arsenite. 1185 43

Aromatase is the cytochrome P450 enzyme responsible for the last step of estrogen biosynthesis, and aromatase inhibitors constitute an important class of drugs in clinical use for the treatment of breast cancer. Nonsteroidal aromatase inhibitors (NSAIs) are competitive inhibitors of aromatase, which bind to the enzyme active site by coordinating the iron atom present in the heme group of the P450 protein. Presently, third generation NSAIs are in use, and research efforts are being carried out both to identify new molecules of therapeutic interest and to clarify the mechanism of action. In this article, we present a survey of the compounds that have been recently reported as NSAIs, to provide a broad view on the general structure-activity relationships of the class. Moreover, starting from the current knowledge of the mechanistic aspects of aromatase action and from recent theoretical work on the molecular modeling of both enzyme and inhibitors, we try to indicate a way to integrate these different studies in view of a more general understanding of the aromeatase-inhibitor system. Finally, some aspects regarding the possible future development of the field are considered briefly.
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PMID:Nonsteroidal aromatase inhibitors: recent advances. 1193 21

Tamoxifen is a major drug used for adjuvant chemotherapy of breast cancer; however, its use has been associated with a small but significant increase in risk of endometrial cancer. In rats, tamoxifen is a hepatocarcinogen, and DNA adducts have been observed in both rat and human tissues. Tamoxifen has been shown previously to be metabolized to reactive products that have the potential to form protein and DNA adducts. Previous studies have suggested a role for P450 3A4 in protein adduct formation in human liver microsomes, via a catechol intermediate; however, no clear correlation was seen between P450 3A4 content of human liver microsomes and adduct formation. In the present study, we investigated the P450 forms responsible for covalent drug-protein adduct formation and the possibility that covalent adduct formation might occur via alternative pathways to catechol formation. Recombinant P450 3A4 catalyzed adduct formation, and this correlated with the level of uncoupling in the P450 incubation, consistent with a role of reactive oxygen species in potentiating adduct formation after enzymatic formation of the catechol metabolite. Whereas P450s 1A1, 2D6, and 3A5 generated catechol metabolite, no covalent adduct formation was observed with these forms. By contrast, P450 2B6, 2C19, and rat liver microsomes catalyzed drug-protein adduct formation but not catechol formation. Drug protein adducts formed specifically with P450 3A4 in incubations using membranes isolated from bacteria expressing P450 3A4 and reductase, as well as in reconstitutions of purified 3A4, suggesting that the electrophilic species reacted preferentially with the P450 enzymes concerned.
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PMID:Bioactivation of tamoxifen by recombinant human cytochrome p450 enzymes. 1201 81

Hormone-dependent breast cancer is stimulated by the female hormones oestrone and oestradiol, therefore compounds which inhibit the specific enzymes involved in the formation of the nitogenic hormones, namely CYP19 aromatase (P450arom) and 17beta-hydroxysteroid dehydrogenase (17beta-HSD) type 1, are targets of therapeutic interest for the treatment of breast cancer. A series of novel 1-[(benzofuran-2-yl)phenylmethyl]1,2,4-triazoles were prepared using a three-step synthesis and evaluated for their inhibitory activity against human placental aromatase in vitro, using [1,2,6,7-3H]androstenedione as the substrate for the aromatase enzyme. Inhibitory activity was dependent on both substituent and position of substitution, with introduction of small electron-withdrawing groups in the phenyl ring showing optimum activity (IC50 ranging from 0.065 to 2.02 microm). Substitution in the benzofuran ring resulted in a loss of activity when substituted at C-5 (IC50 > 20 microm). The compounds were all shown to exhibit weak inhibitory activity against rat testes P450 17 (17,20-lyase), indicating good selectivity towards P450arom.
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PMID:1-[(Benzofuran-2-yl)phenylmethyl]triazoles as steroidogenic inhibitors: synthesis and in vitro inhibition of human placental CYP19 aromatase. 1204 80

Glutathione S-transferases (GSTs) are a family of detoxification isozymes that protect cells by conjugating GSH to a variety of toxic compounds, and they may also play a role in the regulation of both cellular proliferation and apoptosis. We have previously shown that human GST P1-1, which is the most widely distributed extrahepatic isozyme, could be inactivated by the catechol estrogen metabolite 4-hydroxyequilenin (4-OHEN) in vitro [Chang, M., Shin, Y. G., van Breemen, R. B., Blond, S. Y., and Bolton, J. L. (2001) Biochemistry 40, 4811-4820]. In the present study, we found that 4-OHEN and another catechol estrogen, 4,17beta-hydroxyequilenin (4,17beta-OHEN), significantly decreased GSH levels and the activity of GST within minutes in both estrogen receptor (ER) negative (MDA-MB-231) and ER positive (S30) human breast cancer cells. In addition, 4-OHEN caused significant decreases in GST activity in nontransformed human breast epithelial cells (MCF-10A) but not in the human hepatoma HepG2 cells, which lack GST P1-1. We also showed that GSH partially protected the inactivation of GST P1-1 by 4-OHEN in vitro, and depletion of cellular GSH enhanced the 4-OHEN-induced inhibition of GST activity. In addition, 4-OHEN GSH conjugates contributed about 27% of the inactivation of GST P1-1 by 4-OEHN in vitro. Our in vitro kinetic inhibition experiments with 4-OHEN showed that GST P1-1 had a lower K(i) value (20.8 microM) compared to glyceraldehyde-3-phosphate dehydrogenase (GAPDH, 52.4 microM), P450 reductase (PR, 77.4 microM), pyruvate kinase (PK, 159 microM), glutathione reductase (GR, 230 microM), superoxide dismutase (SOD, 448 microM), catalase (562 microM), GST M1-1 (620 microM), thioredoxin reductase (TR, 694 microM), and glutathione peroxidase (GPX, 1410 microM). In contrast to the significant inhibition of total GST activity in these human breast cancer cells, 4-OHEN only slightly inhibited the cellular GAPDH activity, and other cellular enzymes including PR, PK, GR, SOD, catalase, TR, and GPX were resistant to 4-OHEN-induced inhibition. These data suggest that GST P1-1 may be a preferred protein target for equine catechol estrogens in vivo.
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PMID:Inhibition of cellular enzymes by equine catechol estrogens in human breast cancer cells: specificity for glutathione S-transferase P1-1. 1211 4

Tamoxifen, a nonsteroidal antiestrogen, is used widely in the treatment of breast cancer and is undergoing evaluation as a chemopreventive agent. In this study, we investigated several long-term effects of tamoxifen in intact adult female rats following acute treatment at various dosages. The effects of tamoxifen on somatic growth, growth hormone (GH) levels, thyroid hormone levels, and on hepatic cytochrome P450 (P450) expression were compared with those of fulvestrant (ICI 182,780), 17beta-estradiol-3-benzoate, and 4-hydroxytamoxifen under the same experimental conditions. Each compound was injected s.c. for two consecutive days, and rats were killed 37 days after treatment. Tamoxifen decreased body weight and serum triiodothyronine (T3) levels at dosages ranging from 0.5 to 200 mg/kg. Ovary weight, uterus weight, peak plasma GH concentration, and hepatic CYP2A1 content were decreased 37 days after treatment with tamoxifen at a dosage of 20 mg/kg, but expression of other P450 enzymes was not affected. However, tamoxifen and 4-hydroxytamoxifen could not be detected in plasma by high performance liquid chromatography analysis at this time, which suggests that the effects of tamoxifen were mediated indirectly. 4-Hydroxytamoxifen exhibited effects similar to those of tamoxifen, indicating that this metabolite contributes to the in vivo activity of tamoxifen. Estradiol benzoate decreased CYP2A1 and increased CYP3A hepatic levels, but had no effect on serum T3 concentration. In contrast, treatment with ICI 182,780 had little or no effect on the endpoints measured. In summary, 2-day tamoxifen treatment of intact adult female rats resulted in persistent suppression of somatic growth, serum T3 levels, and hepatic CYP2A1 expression.
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PMID:Persistent suppression of hepatic CYP2A1 expression and serum triiodothyronine levels by tamoxifen in intact female rats: dose-response analysis and comparison with 4-hydroxytamoxifen, fulvestrant (ICI 182,780), and 17beta-estradiol-3-benzoate. 1213 Jul 19

Intratumoral expression of aromatase P450 (P450arom) promotes the growth of breast tumors via increased local estrogen concentration. We cloned a novel 101-bp untranslated first exon (I.7) that comprises the 5'-end of 29-54% of P450arom transcripts isolated from breast cancer tissues (n = 7). The levels of P450arom transcripts with exon I.7 were significantly increased in breast tumor tissues and adipose tissue adjacent to tumors. We identified a promoter immediately upstream of exon I.7 and mapped this to about 36 kb upstream of ATG translation start site of the CYP19 (aromatase cytochrome P450) gene. Sequence analysis of I.7 revealed a TATA-less promoter containing an initiator, two consensus GATA sites, and cis-regulatory elements found in megakaryocytes and endothelial type promoters. Luciferase activity directed by the promoter I.7 sequence (-299/+81 bp) was 4-fold greater than a minimum length promoter sequence (-35/+81 bp) in human microvascular endothelial cells (HMEC-1), but only 2-fold greater in MCF-7 breast malignant epithelial cells. There was no promoter activity in primary breast adipose fibroblasts. Site-directed mutations demonstrated that maximal basal promoter activity required two GATA motifs at -146/-141 bp and -196/-191 bp. Gel shift and deoxyribonuclease I footprinting assays demonstrated the binding of GATA-2 transcription factor but not GATA-1 to the -196/-191-bp region. Overexpression of GATA-2 in HMEC-1 cells increases promoter I.7 activity by 5-fold. In conclusion, promoter I.7 is a GATA-2-regulated endothelial promoter of the human CYP19 gene and may increase estrogen biosynthesis in vascular endothelial cells of breast cancer. The activity of this promoter may also be important for intracrine and paracrine effects of estrogen on blood vessels.
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PMID:Cloning and characterization of a novel endothelial promoter of the human CYP19 (aromatase P450) gene that is up-regulated in breast cancer tissue. 1235 90

The oxidative metabolites of estrogen have been proposed to play an important role in the development of some human cancers. The two major pathways of estrogen metabolism, to the carcinogenic 4-hydroxyestradiol (4-OHE2) and to the non-carcinogenic 2-hydroxyestradiol (2-OHE2), are mediated by cytochromes P450 CYP1B1 and CYP1A1, respectively. The expression of CYP1A1 and CYP1B1 is regulated by the aromatic hydrocarbon receptor/Ah receptor nuclear translocator (AhR/ARNT) transcription factor complex. CYP1B1 expression is elevated in a wide range of human cancers but is not found in corresponding normal tissue. Thioredoxin-1 (Trx-1) is a small redox protein that is overexpressed in a number of human cancers. We report that the expression of CYP1B1 mRNA and protein is increased by Trx-1 transfection of MCF-7 human breast cancer cells and decreased by a redox inactive mutant Trx-1. The Trx-1 inhibitor PX-12 inhibits CYP1B1 gene expression. Trx-1 transfected MCF-7 cells show increased AhR/ARNT DNA binding activity that is not due to altered AhR or ARNT protein expression. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD, dioxin) induced expression of CYP1B1 in MCF-7 cells is increased by Trx-1. Trx-1 does not effect the basal expression of CYP1A1, but increases CYP1A1 mRNA in response to TCDD. The redox inactive mutant Trx-1 completely blocks the induction of both CYP1B1 and CYP1A1 by TCDD. Expression of CYP1A1 but not CYP1B1 has been linked to estrogen receptor (ERalpha) status. Trx-1 transfected MCF-7 cells have decreased ERalpha expression, which may account for the lack of CYP1A1 induction by Trx-1 in the absence of ligand. The results suggest that Trx-1 is involved in the constitutive expression of CYP1B1 and is required for the induction of CYP1B1 and CYP1A1 by TCDD in human MCF-7 breast cancer cells.
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PMID:The redox protein thioredoxin-1 regulates the constitutive and inducible expression of the estrogen metabolizing cytochromes P450 1B1 and 1A1 in MCF-7 human breast cancer cells. 1237 70


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