Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027627 (metastases)
 103,950 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Resistance to chemotherapy is a major cause of mortality in advanced cancer patients. In this study, digital karyotyping was used to search for genomic alterations in liver metastases that were clinically resistant to 5-fluorouracil (5-FU). In two of four patients, we identified amplification of an approximately 100-kb region on 18p11.32 that was of particular interest because it contained the gene encoding thymidylate synthase (TYMS), a molecular target of 5-FU. Analysis of TYMS by fluorescence in situ hybridization identified TYMS gene amplification in 23% of 31 5-FU-treated cancers, whereas no amplification was observed in metastases of patients that had not been treated with 5-FU. Patients with metastases containing TYMS amplification had a substantially shorter median survival (329 days) than those without amplification (1,021 days, P <0.01). These data suggest that genetic amplification of TYMS is a major mechanism of 5-FU resistance in vivo and have important implications for the management of colorectal cancer patients with recurrent disease.
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PMID:Digital karyotyping identifies thymidylate synthase amplification as a mechanism of resistance to 5-fluorouracil in metastatic colorectal cancer patients. 1497 Mar 24

Hepatic metastases occur in about half of patients with colorectal cancer. Since hepatic metastases are often not accessible for surgery, chemotherapy of metastases is important. The most commonly used chemotherapy drugs for hepatic metastases are fluorouracil, irinotecan, and oxaliplatin. Several enzymes are known to be involved in the catabolism and anabolism of these drugs, and the activity of these enzymes varies greatly between individuals. The causes of this variation include genetic polymorphisms, different regulation between normal and cancer tissue, and the influence of chemotherapy on enzyme expression. The varying enzyme activity may have an important effect on the outcome of chemotherapy. Several studies confirm the influence of the activity of thymidylate synthase, thymidine phosphorylase and dihydropyrimidine dehydrogenase on the outcome of fluorouracil therapy for colorectal cancer, with higher enzyme activities predicting lower treatment efficacy. Although fewer studies are available regarding therapy of hepatic metastases, the same relationship between thymidylate synthase activity and outcome of fluorouracil therapy observed for primary colorectal cancer was found. For the other two enzymes, only a few studies are available, but the results indicate similarly that higher enzyme activity seems to be disadvantageous. The enzymes responsible for the activation, metabolism and mechanism of action of irinotecan, namely carboxylesterase 2, cytochrome P450 (CYP) 3A4, uridine diphosphate glucuronosyltransferase isoform 1A1 (UGT1A1), and topoisomerase-I, also exhibit variable interindividual activity. Thus, there may be an association between enzyme activity and response to therapy. For instance, in patients with colorectal cancer, higher enzyme activity of topoisomerase-I seems to be predictive of a better response to irinotecan. CYP3A4 and UGT1A1 activity levels might be predictive of irinotecan toxicity rather than efficacy. The degradation of oxaliplatin is independent of potentially varying enzyme activity, but for this drug, the DNA repair enzyme ERCC1 may influence the survival time after chemotherapy. Taken together, the available data indicate the importance of the different enzyme activities on the outcome of chemotherapy of hepatic metastases in colorectal cancer. More information is needed, especially for the newer drugs irinotecan and oxaliplatin. However, the existing data are very promising in respect to the potential to guide dose and drug selection for more efficient and less toxic chemotherapy of hepatic metastases.
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PMID:Pharmacogenomics of fluorouracil, irinotecan, and oxaliplatin in hepatic metastases of colorectal cancer: clinical implications. 1572 86

Colorectal carcinoma shows several sex-related differences with regard to incidence, response to chemotherapy and microsatellite instability. These differences may relate to differential expression of ERbeta1 (wild-type) as well as the truncated ERbeta2 and ERbeta5 splice variant isoforms, which have recently been detected in normal and malignant colorectal epithelium. This hypothesis was tested through the study of ERbeta isoform protein and/or mRNA expression amongst 91 primary colorectal carcinoma cases and 20 colorectal carcinoma cell lines. Study of the latter showed an absolute correlation between mRNA and protein expressions for ERbeta1 and ERbeta2. ERbeta1 and ERbeta2 protein expression was lost in 22% and 49%, respectively, of the primary colorectal carcinomas. By contrast, ERbeta5 expression was found in all primary colorectal carcinomas and all colorectal carcinoma cell lines studied. Lower ERbeta1 protein expression was associated with poorer differentiation, higher pT stage and absence of microsatellite instability. Higher ERbeta2 protein expression was associated with right-sided location and presence of lymph node metastases. Protein expression of ERbeta1 correlated positively with expression of the oestrogen-responsive protein trefoil factor 1 (TFF1). There was no correlation between ERbeta protein isoform expression and response to 5-fluorouracil therapy, tumour proliferation, or thymidylate synthase expression. These data suggest that ERbeta1 and/or ERbeta2 isoform expression may have prognostic value and may explain sex-related differences in microsatellite instability and colorectal carcinoma. The opposing associations shown by ERbeta1 and/or ERbeta2 in relation to colorectal carcinoma are in keeping with differential activities shown by the two isoforms.
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PMID:ERbeta isoform expression in colorectal carcinoma: an in vivo and in vitro study of clinicopathological and molecular correlates. 1595 65

The purpose of this study was to estimate the possibility of using thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), and p53 as predictive values of clinical outcome in adenoid cystic carcinoma (ACC). The expressions of TS, DPD, and p53 were examined with immunohistochemistry in 27 ACC patients, and the association with clinicopathological factors was determined. Cases with high DPD expression had significantly higher distant metastasis rates compared to those with low DPD expression (p=0.001), whereas neither TS nor p53 expression showed any significant correlation to clinicopathological factors. Interestingly, six of 14 early-stage patients had distant metastases and all of their tumors showed high DPD expression. Kaplan-Meier analysis revealed that a solid histological pattern and distant metastasis correlated with a poor prognosis. In early-stage patients, whose tumor was completely resected, those with high TS or DPD expression had a worse prognosis compared to those with low expression, but the difference did not reach statistical significance (TS, p=0.178; DPD, p=0.251). Our results suggest that assessment of DPD expression in ACC may be a useful tool in determining the mode of treatment as well as evaluating clinical outcome.
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PMID:Expression of thymidylate synthase and dihydropyrimidine dehydrogenase in adenoid cystic carcinoma of the head and neck: correlation with clinical outcome. 1707 99

Folates play a key role in one-carbon metabolism essential for the biosynthesis of purines, thymidylate and hence DNA replication. The antifolate methotrexate has been rationally-designed nearly 60 years ago to potently block the folate-dependent enzyme dihydrofolate reductase (DHFR) thereby achieving temporary remissions in childhood acute leukemia. Recently, the novel antifolates raltitrexed and pemetrexed that target thymidylate synthase (TS) and glycineamide ribonucleotide transformylase (GARTF) were introduced for the treatment of colorectal cancer and malignant pleural mesothelioma. (Anti)folates are divalent anions which predominantly use the reduced folate carrier (RFC) for their cellular uptake. (Anti)folates are retained intracellularly via polyglutamylation catalyzed by folylpoly-gamma-glutamate synthetase (FPGS). As the intracellular concentration of antifolates is critical for their pharmacologic activity, polyglutamylation is a key determinant of antifolate cytotoxicity. However, anticancer drug resistance phenomena pose major obstacles towards curative cancer chemotherapy. Pre-clinical and clinical studies have identified a plethora of mechanisms of antifolate-resistance; these are frequently associated with qualitative and/or quantitative alterations in influx and/or efflux transporters of (anti)folates as well as in folate-dependent enzymes. These include inactivating mutations and/or down-regulation of the RFC and various alterations in the target enzymes DHFR, TS and FPGS. Furthermore, it has been recently shown that members of the ATP-binding cassette (ABC) superfamily including multidrug resistance proteins (MRP/ABCC) and breast cancer resistance protein (BCRP/ABCG2) are low affinity, high capacity ATP-driven (anti)folate efflux transporters. This transport activity is in addition to their established facility to extrude multiple cytotoxic agents. Hence, by actively extruding antifolates, overexpressed MRPs and/or BCRP confer antifolate resistance. Moreover, down-regulation of MRPs and/or BCRP results in decreased folate efflux thereby leading to expansion of the intracellular folate pool and antifolate resistance. This chapter reviews and discusses the panoply of molecular modalities of antifolate-resistance in pre-clinical tumor cell systems in vitro and in vivo as well as in cancer patients. Currently emerging novel strategies for the overcoming of antifolate-resistance are presented. Finally, experimental evidence is provided that the identification and characterization of the molecular mechanisms of antifolate-resistance may prove instrumental in the future development of rationally-based novel antifolates and strategies that could conceivably overcome drug-resistance phenomena.
Cancer Metastasis Rev 2007 Mar
PMID:Molecular basis of antifolate resistance. 1733 44

Following resection of hepatic colorectal metastases, there are few criteria for predicting which patients have more aggressive disease and are, therefore, more likely to experience recurrence and reduced survival. Traditionally, primary tumor stage, preoperative carcinoembryonic antigen level, time from primary tumor treatment to diagnosis of hepatic metastases (disease-free interval), hepatic tumor size, number of hepatic metastases, and presence of extrahepatic disease have been reported to be predictors of survival after resection. However, the data regarding the prognostic importance of these clinicopathologic factors are inconsistent and conflicting. Therefore, conventional clinicopathologic factors may be inadequate for the purposes of prognostication. More recently, there has been increased interest in identifying biologic indicators that may help better define patients at risk for recurrence after hepatic resection for colorectal metastases. Recent studies have shown that proliferation markers such as p53 expression, tritiated thymidine uptake, thymidylate synthase, Ki-67, and human telomerase reverse transcriptase may be better predictors of outcome after resection of hepatic colorectal metastases. Moreover, tumor response to preoperative chemotherapy may also prove to be a useful predictor of outcome following liver resection for colorectal metastases.
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PMID:Shifting from clinical to biologic indicators of prognosis after resection of hepatic colorectal metastases. 1743 Jun 90

Ezrin is a membrane-cytoskeleton anchor, which, in experimental models, regulates tumor cell invasion and metastatic ability. We carried out immunohistochemical analysis of ezrin in 74 advanced colorectal cancer patients and correlated it to clinicopathologic variables and disease outcome. In contrast to the predominantly membraneous immunoreactivity of normal colorectal epithelium, ezrin expression in the colorectal cells was typically cytoplasmic. Altogether, 16.2% (12/74) of the tumors showed negative/weak ezrin staining, 35.1% (26/74) had moderate staining, and 48.6% (36/74) had intense staining. The expression was more intense in colon than in rectal carcinomas (P = .003). Increased ezrin expression was associated with adverse outcome, that is, shorter disease-specific survival; 48.3 months and 36.6 months for negative-weak versus intense expression (P = .041) as well as shorter survival with metastases at 36 months (P = .030); the metastases(36) rates in ezrin(neg/weak), ezrin(moderate), ezrin(intense) are 58.3%, 25.0%, and 18.4%, respectively. In univariate survival analysis, dichotomized (negative/weak versus moderate/strong) ezrin expression significantly predicted both the 5-year disease specific survival (P = .035) and 5-year metastases (P = .018) but lost this predictive power in multivariate (Cox) analysis. High ezrin expression was also related to high E-cadherin (cytoplasmic) expression, DNA aneuploidy, and high thymidylate synthase expression (P = .046, P = .042, P = .046, respectively). These results suggest that ezrin may play a role in colorectal cancer progression and that ezrin expression might provide clinically valuable information in predicting the biological behavior of colorectal cancer.
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PMID:Intense cytoplasmic ezrin immunoreactivity predicts poor survival in colorectal cancer. 1870 Nov 34

The published data about thymidylate synthase (TS) expression and its predictive value in advanced colorectal cancer (CRC) patients receiving fluoropyrimidine-based chemotherapy seemed inconclusive. To derive a more precise estimation of the relationship, a metaanalysis was performed. Studies have been identified by searching PubMed and Embase. Inclusion criteria were advanced CRC patients, received fluoropyrimidine-based chemotherapy and evaluation of TS expression and overall response rate (ORR). The relative ratio (RR) for ORR in patients with low-TS expression over those with high-TS expression with 95% confidence interval (CI) was calculated for each study as an estimation of the predictive effect of TS. A total of 24 studies including 1,112 patients were involved in this metaanalysis. The overall RR was 2.20 (95% CI, 1.82-2.66; p = 0.000). For studies evaluating TS expression in metastatic lesions, the pooled RR was 3.23 (95% CI, 2.27-4.59; p = 0.000); for studies testing TS expression in primary lesions, a pooled RR of 1.89 (95% CI, 1.45-2.48; p = 0.000) was estimated. Focusing the analysis on immunohistochemistry (IHC)-based or RTPCR-based assessments, the pooled RR was 1.83 (95% CI, 1.44-2.34; p = 0.000) and 2.96 (95% CI, 2.07-4.22; p = 0.000), respectively. The results indicated that low-TS expression tumors in advanced CRC patients were more sensitive to fluoropyrimidine-based chemotherapy. Subgroup analyses indicated that the predictive value of TS expression evaluated in metastases was more prominent than that of primary lesions, and that TS expression tested by RTPCR was also of greater predictive value than by IHC.
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PMID:Predictive value of thymidylate synthase expression in advanced colorectal cancer patients receiving fluoropyrimidine-based chemotherapy: evidence from 24 studies. 1872 95

Resistance to chemotherapy is believed to be a major cause of treatment failure in pancreatic cancer. Thus, it is necessary to explore alternative therapeutic modalities to overcome drug resistance in pancreatic cancer treatment. We tested the hypothesis that Src tyrosine kinase inhibition could augment the chemosensitivity of 5-fluorouracil (5-FU)-resistant human pancreatic cancer cells to 5-FU. As detected by MTT proliferation assay, propidium iodide and annexin V staining, a combination of 5-FU+Src kinase inhibitor PP2 (4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine) reflected the chemotherapeutic sensitivity and restored the 5-FU-induced apoptosis in 5-FU-resistant cells. Furthermore, when small-interfering RNA approach to silence Src gene expression was applied, the degree of 5-FU-induced apoptosis was increased in all cell lines independently of the chemoresistance status. Western blotting and RT-PCR analysis revealed that the expression of thymidylate synthase (TS) was higher in 5-FU-resistant cells, however, decreased significantly after pretreatment with PP2. Furthermore, the combination of 5-FU+PP2 decreased the 5-FU-induced activation of epidermal growth factor receptor (EGFR)-AKT pathway. Finally, PP2 in combination with 5-FU substantially decreased the in vivo tumor growth and inhibited distant metastases. Taken together, 5-FU chemoresistance can be reversed through indirect TS regulation by inhibiting Src tyrosine kinase. A potential mechanism of action of Src kinase inhibitors on 5-FU chemosensitivity might be linked to the inhibition of 5-FU-induced EGFR-AKT activation.
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PMID:Inhibition of Src tyrosine kinase reverts chemoresistance toward 5-fluorouracil in human pancreatic carcinoma cells: an involvement of epidermal growth factor receptor signaling. 1879 7

5-Fluorouracil (5-FU) continues to be widely used for treatment of gastrointestinal cancers. Because many tumors show primary or acquired resistance, it is important to understand the molecular basis underlying the mechanism of resistance to 5-FU. In addition to its effect on thymidylate synthase inhibition and DNA synthesis, 5-FU may also influence RNA metabolism. Our previous studies revealed that colorectal cancer cells resistant to bolus 5-FU (HCT-8/4hFU) showed significantly decreased incorporation of the drug into RNA. Resistance to bolus 5-FU was associated with lower expression of UMP kinase (UMPK), an enzyme that plays an important role in the activation of 5-FU to 5-FUTP and its incorporation into RNA. Activities of other 5-FU-metabolizing enzymes (e.g., thymidine kinase, uridine phosphorylase, thymidine phosphorylase, and orotate phosphoribosyltransferase) remained unchanged between sensitive and resistant cell lines. Herein, we show that UMPK down-regulation in 5-FU-sensitive cells (HCT-8/P) induces resistance to bolus 5-FU treatment. Moreover, HCT-8/4hFU cells are even more cross-resistant to treatment with 5-fluorouridine, consistent with the current understanding of 5-fluorouridine as a RNA-directed drug. Importantly, colorectal cancer hepatic metastases isolated from patients clinically resistant to weekly bolus 5-FU/leucovorin treatment exhibited decreased mRNA expression of UMPK but not thymidylate synthase or dihydropyrimidine dehydrogenase compared with tumor samples of patients not previously exposed to 5-FU. Our findings provide new insights into the mechanisms of acquired resistance to 5-FU in colorectal cancer and implicate UMPK as an important mechanism of clinical resistance to pulse 5-FU treatment in some patients.
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PMID:Decreased levels of UMP kinase as a mechanism of fluoropyrimidine resistance. 1938 47


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