Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C1140680 (ovarian cancer)
 28,141 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

CPT-11 belongs to the class of topoisomerase I inhibitors, and it acts as a prodrug of SN-38, which is approximately 100-1000-fold more cytotoxic than the parent drug. CPT-11 has shown a broad spectrum of antitumor activity in preclinical models as well as clinically, with responses observed in various disease types including colorectal, lung, cervical, and ovarian cancer. The pharmacokinetics and metabolism of CPT-11 are extremely complex and have been the subject of intensive investigation in recent years. Both CPT-11 and SN-38 are known in an active lactone form and an inactive carboxylate form, between which an equilibrium exists that depends on the pH and the presence of binding proteins. CPT-11 is subject to extensive metabolic conversion by various enzyme systems, including esterases to form SN-38, UGT1A1 mediating glucuronidation of SN-38, as well as CYP3A4, which forms several pharmacologically inactive oxidation products. Elimination routes of CPT-11 also depend on the presence of drug-transporting proteins, notably P-glycoprotein and canalicular multispecific organic anion transporter, present on the bile canalicular membrane. The various processes mediating drug elimination, either through metabolic breakdown or excretion, likely impact substantially on interindividual variability in drug handling. Strategies to individualize CPT-11 administration schedules based on patient differences in enzyme or protein expression or by coadministration of specific agents modulating side effects are under way and may ultimately lead to more selective chemotherapeutic use of this agent.
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PMID:Clinical pharmacokinetics and metabolism of irinotecan (CPT-11). 1148 91

CYP3A4 is involved in the metabolism of endogenous steroids, and an allelic variant, CYP3A4*1B, consisting of an A to G polymorphism within the 5'-flanking region termed the nifedipine-specific response element (NFSE) has been associated with high grade and advanced stage of prostate cancers. Because steroid hormone exposure is known to influence breast and ovarian cancer risk, we conducted case-control studies to assess the relationship between CYP3A4*1B and risk of breast or ovarian cancer. CYP3A4 NFSE genotype was determined in 951 breast cancer cases and 500 controls frequency matched for age and 488 ovarian cancer cases and 276 controls of similar age distribution. Case-control analyses and comparisons of genotype distributions were conducted by unconditional logistic regression. In addition, the functional significance of the CYP3A4*1B polymorphism was assessed by analysis of CYP3A4-reporter gene constructs transiently transfected into liver-derived cell lines and primary cultures of well-differentiated rat hepatocytes. The GG genotype was rare in all groups (0-0.4%). There was no risk of cancer associated with the AG/GG genotypes combined, with an OR (95% CI) of 0.86 (0.54-1.33) for breast cancer (P = 0.5), and 1.51 (0.80-2.89) for ovarian cancer (P = 0.2). Analysis of CYP3A4-luciferase constructs showed that CYP3A4*1B did not consistently affect reporter gene activity. Our data suggest that the CYP3A4*1B polymorphism is not associated with risk of breast or ovarian cancer. In support of this negative finding, in-vitro functional studies indicate that NFSE genotype is not a critical factor in the transcriptional activity of the CYP3A4 5'-flanking region, and is thus unlikely to modulate CYP3A4-mediated metabolism of steroids.
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PMID:The CYP3A4*1B polymorphism has no functional significance and is not associated with risk of breast or ovarian cancer. 1214 25

Hypoxia-inducible factor 1 (HIF-1) is a heterodimeric basic helix-loop-helix transcription factor composed of HIF-1alpha and HIF-1beta subunits. HIF-1 expression is induced by hypoxia, growth factors, and activation of oncogenes. HIF-1 activates downstream target genes such as vascular endothelial growth factor A (VEGF-A), which plays an important role in tumor progression and angiogenesis. Estrogen exposure is considered to be the major risk factor for ovarian cancer. Estradiol (E2) is usually metabolized by CYP1A1/1A2 and CYP3A4 to the 2-hydroxy estradiol (2-OHE2) and 4-hydroxy estradiol (4-OHE2) in human liver. Many reports have suggested that the formation of 4-OHE2 is important for mammary carcinogenesis. However, the formation of 2-OHE2 may play an important role in exhibiting anticarcinogenic effects. In the present study, we have demonstrated that one of the catechol estrogen metabolites of E2, 4-OHE2, induces HIF-1alpha and VEGF-A expression at protein level in two human ovarian cancer cell lines, OVCAR-3 and A2780-CP70 cells, in dose- and time-dependent manners, whereas the other catechol estrogen metabolite of E2, 2-OHE2, does not alter HIF-1alpha and VEGF-A expression. To explore the mechanism of 4-OHE2-induced HIF-1alpha and VEGF-A expression, we studied whether phosphatidylinositol 3-kinase (PI3K) or mitogen-activated protein kinase (MAPK) signaling pathways are involved in 4-OHE2-induced HIF-1alpha and VEGF-A expression. Our findings indicate that PI3K inhibitors, LY294002 and wortmannin, inhibited HIF-1alpha and VEGF-A expression, whereas MAPK inhibitor, PD98059, did not alter HIF-1alpha and VEGF-A expression induced by 4-OHE2. 4-OHE2, but not 2-OHE2, also induced Akt phosphorylation at Ser473 in dose- and time-dependent manners, and LY294002 and wortmannin inhibited Akt phosphorylation at Ser473 induced by 4-OHE2. Our results also indicated that the mTOR/FRAP inhibitor, rapamycin, inhibited 4-OHE2-induced HIF-1alpha and VEGF-A expression. These results suggest that the PI3K/Akt/FRAP signaling pathway is required for HIF-1alpha and VEGF-A expression induced by 4-OHE2, whereas the MAPK pathway is not required. The finding that induction of HIF-1alpha and VEGF-A expression occurs via the activation of the PI3K/Akt/FRAP signaling pathway could be an important mechanism of 4-OHE2-induced carcinogenesis.
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PMID:4-Hydroxy estradiol but not 2-hydroxy estradiol induces expression of hypoxia-inducible factor 1alpha and vascular endothelial growth factor A through phosphatidylinositol 3-kinase/Akt/FRAP pathway in OVCAR-3 and A2780-CP70 human ovarian carcinoma cells. 1505 Apr 14

Interindividual differences in the pharmacokinetics of paclitaxel and its metabolites in Japanese ovarian cancer patients were investigated in relation to genetic polymorphisms of the CYP2C8, CYP3A4, and MDR1 genes. The area under the concentration-time curve (AUC) ratios of paclitaxel/6alpha-hydroxypaclitaxel and paclitaxel/3 -p-hydroxypaclitaxel calculated as the metabolic index of CYP2C8 and CYP3A4 showed 13- and 12-fold interindividual variations, respectively. No patient had any CYP2C8 variants, while 2 patients were heterozygotes of CYP3A4*16. For the MDR1 gene, the frequencies of -129C, 1236C, 2677T, 2677A, and 3435T alleles were 2.2%, 8.7%, 56.5%, 4.4%, and 52.2%, respectively. Subjects possessing the 3435T allele had a significantly (P < .05) higher AUC of 3'- p-hydroxypaclitaxel compared to those possessing the 3435C allele. Leukocytopenia was significantly (P < .05) related to the AUC of paclitaxel. Genotyping of the CYP2C8, CYP3A4, and MDR1 genes might not be essential to predict adverse effects of paclitaxel in Japanese patients, although an allelic variant of MDR1 may functionally affect the pharmacokinetics of its metabolite.
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PMID:Pharmacokinetics of paclitaxel in ovarian cancer patients and genetic polymorphisms of CYP2C8, CYP3A4, and MDR1. 1590 49

Therapy-related leukemia or myelodysplasia (t-leuk/MDS) is a serious problem that is increasing in frequency. We studied the clinical characteristics of 96 patients (pts) with a mean age of 48 years, and analyzed the molecular parameters that could predispose to t-leuk/MDS. Hematological malignancies were the most common primary (53%), followed by breast and ovarian cancer (30% combined). The mean latency until the development of t-AML was 45.5 months. Median survival was 10 months. Cytogenetics was abnormal in 89% of pts. FLT3 internal tandem duplications were found in six of 41 (14.6%) pts, of whom four had an abnormal karyotype. Analysis of drug metabolism and disposition genes showed a protective effect of the CYP3A4 1*B genotype against the development of t-leuk/MDS, whereas the CC genotype of MDR1 C3435T and the NAD(P)H:quinone oxidoreductase1 codon 187 polymorphism were both noncontributory. Microsatellite instability (MSI) analysis using fluoresceinated PCR with ABI sequence analyzer demonstrated that 41% of pts had high levels of MSI in four or more of 10 microsatellite loci. Immunohistochemistry demonstrated reduced expression of MSH2 and MLH1 in 6/10 pts with MSI as compared to 0/5 of pts without MSI. In conclusion, genetic predisposition as well as epigenetic events contribute to the etiology of t-AML/MDS.
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PMID:Therapy-related leukemia: clinical characteristics and analysis of new molecular risk factors in 96 adult patients. 1616 58

Sex hormones have been implicated in prostate carcinogenesis and are thought to modulate cell proliferation and growth. To investigate the association between polymorphisms in hormone-related genes and prostate cancer risk, we conducted a two-stage, case-control study within the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Using DNA extracted from blood specimens, we initially genotyped 14 single nucleotide polymorphisms in genes involved in hormone regulation or metabolism (AKR1C3, CYP1A1, CYP1B1, CYP3A4, ESR1, GNRH1, HSD173B, HSD3B2, SHBG, and SRD5A2) in 488 prostate cancer cases and 617 matched controls. Heterozygotes at SHBG D356N were found to be associated with an increased risk of prostate cancer compared with the homozygous wild type, particularly among non-Hispanic whites (odds ratio, 1.54; 95% confidence interval, 1.13-2.09; P = 0.006). No significant associations were observed with the other polymorphisms. The SHBG D356N polymorphism, which has potential functional significance, was subsequently genotyped in additional 769 cases and 1,168 controls. Overall, SHBG D356N heterozygotes were found to have an increased risk of prostate cancer among whites (odds ratio, 1.34; 95% confidence interval, 1.10-1.63; P = 0.0007). This study suggests that genetic variation in SHBG may influence prostate cancer susceptibility.
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PMID:Variant in sex hormone-binding globulin gene and the risk of prostate cancer. 1722 Mar 47

The search for genetic variants associated with ovarian cancer risk has focused on pathways including sex steroid hormones, DNA repair, and cell cycle control. The Ovarian Cancer Association Consortium (OCAC) identified 10 single-nucleotide polymorphisms (SNPs) in genes in these pathways, which had been genotyped by Consortium members and a pooled analysis of these data was conducted. Three of the 10 SNPs showed evidence of an association with ovarian cancer at P< or =0.10 in a log-additive model: rs2740574 in CYP3A4 (P=0.011), rs1805386 in LIG4 (P=0.007), and rs3218536 in XRCC2 (P=0.095). Additional genotyping in other OCAC studies was undertaken and only the variant in CYP3A4, rs2740574, continued to show an association in the replication data among homozygous carriers: OR(homozygous(hom))=2.50 (95% CI 0.54-11.57, P=0.24) with 1406 cases and 2827 controls. Overall, in the combined data the odds ratio was 2.81 among carriers of two copies of the minor allele (95% CI 1.20-6.56, P=0.017, p(het) across studies=0.42) with 1969 cases and 3491 controls. There was no association among heterozygous carriers. CYP3A4 encodes a key enzyme in oestrogen metabolism and our finding between rs2740574 and risk of ovarian cancer suggests that this pathway may be involved in ovarian carcinogenesis. Additional follow-up is warranted.
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PMID:Validating genetic risk associations for ovarian cancer through the international Ovarian Cancer Association Consortium. 1912 55

The purpose of this study was to evaluate the role of sequence variants in the CYP2C8, ABCB1 and CYP3A4 genes and the CYP3A4 phenotype for the pharmacokinetics and toxicity of paclitaxel in ovarian cancer patients. Thirty-eight patients were treated with paclitaxel and carboplatin. The genotypes of CYP2C8*1B, *1C, *2, *3, *4, *5, *6, *7, *8 and P404A, ABCB1 G2677T/A and C3435T, as well as CYP3A4*1B, were determined by pyrosequencing. Phenotyping of CYP3A4 was performed in vivo with quinine as a probe. The patients were monitored for toxicity and 23 patients underwent a more extensive neurotoxicity evaluation. Patients heterozygous for G/A in position 2677 in ABCB1 had a significantly higher clearance of paclitaxel than most other ABCB1 variants. A lower clearance of paclitaxel was found for patients heterozygous for CYP2C8*3 when stratified according to the ABCB1 G2677T/A genotype. In addition, the CYP3A4 enzyme activity in vivo affected which metabolic pathway was dominant in each patient, but not the total clearance of paclitaxel. The exposure to paclitaxel correlated to the degree of neurotoxicity. Our findings suggest that interindividual variability in paclitaxel pharmacokinetics might be predicted by ABCB1 and CYP2C8 genotypes and provide useful information for individualized chemotherapy.
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PMID:Pharmacogenetic studies of Paclitaxel in the treatment of ovarian cancer. 1914 48

Using the most comprehensive approach to selecting polymorphisms to date, we sought to examine whether time to recurrence in ovarian cancer was associated with common inherited variation in eight genes involved in drug metabolism, multi-drug resistance, or DNA repair, namely ABCB1, CYP2C8, CYP3A4, ERCC1, ERCC2, GSTM1, XPC, and XRCC1. Invasive epithelial ovarian cancer patients (N=445) seen at the Mayo Clinic from 1999 to 2009 with 275 observed recurrences or deaths were analyzed at 94 SNPs in these candidate genes. Cox regression was used to estimate hazard ratios and 95% confidence intervals for each single nucleotide polymorphism (SNP) and outcome (defined as time to recurrence or death). Analyses were conducted at the gene level and on case subsets defined by histopathology and chemotherapeutic agent. At ABCB1, minor alleles at several SNPs were associated with outcome, with the most significant being the intronic SNP rs12334183 (HR=0.65, 95% Cl 0.51-0.83; p=0.0005). Overall variation in ABCB1 was predictive of outcome as well (p=0.003). At ERCC2, minor alleles at several SNPs were associated with outcome among women with high-grade serous disease (e.g., rs238417, HR 0.74, 95% Cl 0.59-0.92; p=0.006). No associations with outcome were observed in GSTM1, CYP2C8, CYP3A4, ERCC1, XPC, or XRCC1. In summary, inherited variation in ABCB1 and ERCC2 was associated with outcome in patients with ovarian cancer seen at the Mayo Clinic. As the associated SNPs have not been studied previously in ovarian cancer, these findings suggest novel sites of variation which may, in part, explain the range of treatment responses seen in this disease.
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PMID:Polymorphisms in ABCB1 and ERCC2 associated with ovarian cancer outcome. 2168 33

Cytochrome P450 proteins are the most important enzymes involved in metabolic activation or detoxification of various drugs used in clinical practice. However, some drug metabolism pathways may be responsible for their increased toxicity. New expression systems of cytochrome P450 proteins in mammalian cells, including human, are designed to explore the influence of metabolism on the cellular and molecular mechanisms of action of potential drugs and those used therapeutically. They can also be used to study the effect of tested compounds on activity and expression of metabolizing enzymes. Human tumor cell lines with overexpression of cytochrome P450 isoenzymes are of particular importance, especially in studies of potential chemotherapeutics. The HepG2 cell line, derived from human liver cancer, is the most commonly used in studies on drug metabolism and toxicity. However, due to the low level of metabolizing enzymes in these cells, the Hep3A4 cell line with overexpression of CYP3A4 isoenzyme was developed. The stable overexpression of cytochrome P450 isoenzymes was also obtained in other human cancer cell lines, including hepatoma HepaRG cells, ovarian cancer IGROV-1 cells, colon cancer Caco-2, and LS180 cells. This review describes currently developed bacterial, yeast, insect and mammalian (including human) cytochrome P450 protein expression systems, in terms of their advantages and disadvantages in the context of their suitability for basic research and use on a commercial scale.
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PMID:[Expression systems of cytochrome P450 proteins in studies of drug metabolism in vitro]. 2173 21


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