UMLS:C0009402 - FACTA Search

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Query: UMLS:C0009402 (colorectal cancer)
53,228 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Activation of 5-fluorouracil into its nucleotides requires phosphorylation by three pathways involving orotate phosphoribosyl-transferase (OPRT), uridine phosphorylase (UP), or thymidine phosphorylase (TP). In this study, we investigated the association between gene expressions of these three enzymes and antitumour effect. Gene expressions in primary colorectal tumours were analysed by a real-time reverse transcriptional-polymerase chain reaction method in 37 patients receiving oral treatment of tegafur-uracil and leucovorin for metastatic diseases. The median values of OPRT mRNA expressions were 1.39 and 0.85 for responding tumours and nonresponding tumours, respectively, showing a statistically significant difference (P=0.0008). Responding tumours had statistically lower expressions of TP mRNA than nonresponding tumours (P=0.006). However, there was no difference in UP mRNA expression between responding and nonresponding tumours. Patients with high OPRT (>/=1.0) gene expression survived longer than those with low OPRT (<1.0) expression. Dihydropyrimidine dehydrogenase (DPD) gene expressions were measured. Responding tumours had a statistically higher OPRT/DPD ratio than the nonresponding ones (P=0.003). When the median value of the OPRT/DPD ratio was selected as the cutoff value, patients with a high OPRT/DPD ratio survived statistically longer than those with a low ratio (P=0.0014). In conclusion, both the expression of OPRT gene and the OPRT/DPD ratio might be useful as predictive parameters for the efficacy of fluoropyrimidine-based chemotherapy for metastatic colorectal cancer.
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PMID:Both gene expression for orotate phosphoribosyltransferase and its ratio to dihydropyrimidine dehydrogenase influence outcome following fluoropyrimidine-based chemotherapy for metastatic colorectal cancer. 1456 21

5-Fluorouracil (5-FU) is the most common chemotherapeutic agent used in the treatment of colorectal cancer, yet objective response rates are low. Recently, camptothecin (CPT) has emerged as an effective alternative therapy. Decisive means to determine treatment, based on the likelihood of response to each of these agents, could greatly enhance the management of this disease. Here, the ability of cDNA microarray-generated basal gene expression profiles to predict apoptotic response to 5-FU and CPT was determined in a panel of 30 colon carcinoma cell lines. Genes whose basal level of expression correlated significantly with 5-FU- and CPT-induced apoptosis were selected, and their predictive power was assessed using a "leave one out" jackknife cross-validation strategy. Selection of the 50 genes best correlated with 5-FU-induced apoptosis, but not 50 randomly selected genes, significantly predicted response to this agent. Importantly, this gene expression profiling approach predicted response more effectively than four previously established determinants of 5-FU response: thymidylate synthase and thymidine phosphorylase activity; and p53 and mismatch repair status. Furthermore, reanalysis of the database demonstrated that selection of the 149 genes best correlated with CPT-induced apoptosis maximally and significantly predicted response to this agent. These studies demonstrate that the basal gene expression profile of colon cancer cells can be used to predict and distinguish response to multiple chemotherapeutic agents and establish the potential of this methodology as a means by which rational decisions regarding choice of therapy can be approached.
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PMID:Gene expression profiling-based prediction of response of colon carcinoma cells to 5-fluorouracil and camptothecin. 1469 96

TAS-102 is a new oral anti-tumor drug preparation, composed of a 1:0.5 mixture (on a molar basis) of alpha,alpha,alpha-tri-fluorothymidine (FTD) and thymidine phosphorylase inhibitor (TPI). TAS-102 is currently undergoing clinical trials, and has been demonstrated to have at least 2 mechanisms; inhibition of thymidylate synthase (TS) and incorporation into DNA. 5-FU is widely used in the treatment of solid tumor, but the inherent or acquired resistance of certain tumors to 5-FU therapy is a major clinical problem. In the present study, we investigated FTD in vitro and in vivo comparing with 5-FU and using FU-resistant cells. There was no relationship between FTD and 5-FU growth inhibition effect in vitro. A different sensitivity pattern was observed by the log-mean graph. We next investigated the anti-tumor activity of TAS-102 in a FU-resistant xenograft model. Comparative efficacy was observed between FU-resistant cell and its parent cell. We also studied the influence of TAS-102 on liver metastasis in a mouse model of human colorectal cancer, because liver metastasis of colorectal cancer is associated with patient survival. Human cancer DNA was detected by PCR, and TAS-102 markedly inhibited the number of liver metastasis. A novel angiogenic factor, platelet-derived endothelial cell growth factor (PD-ECGF), was shown to be identical to a previously characterized intracellular enzyme, thymidine phosphorylase, TAS-102 can be expected to have not only anti-tumor cytocidal effects but also antiangiogenesis activity and may inhibit liver metastasis. Our findings suggested that TAS-102 is a promising candidate for clinical use and can be expected to decrease minimal residual disease.
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PMID:A novel antimetabolite, TAS-102 retains its effect on FU-related resistant cancer cells. 1501 Aug 54

To elucidate mechanisms of resistance to chemotherapies currently used in the first-line treatment of advanced colorectal cancer, we have developed a panel of HCT116 p53 wild-type (p53(+/+)) and null (p53(-/-)) isogenic colorectal cancer cell lines resistant to the antimetabolite 5-fluorouracil (5-FU), topoisomerase I inhibitor irinotecan (CPT-11), and DNA-damaging agent oxaliplatin. These cell lines were generated by repeated exposure to stepwise increasing concentrations of each drug over a period of several months. We have demonstrated a significant decrease in sensitivity to 5-FU, CPT-11, and oxaliplatin in each respective resistant cell line relative to the parental line as determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide analysis, with increases in IC(50 (72 h)) concentrations ranging from 3- to 65-fold. Using flow cytometry, we have also demonstrated compromised apoptosis and cell cycle arrest in 5-FU-, oxaliplatin-, and CPT-11-resistant cell lines compared with the parental lines after exposure to each drug. In addition, we found that resistance to 5-FU and oxaliplatin was higher in parental p53(-/-) cells compared with parental p53(+/+) cells, with an approximately 5-fold increase in IC(50 (72 h)) for each drug. In contrast, the IC(50 (72 h)) doses for CPT-11 were identical in the p53 wild-type and null cell lines. Furthermore, apoptosis after treatment with 5-FU and oxaliplatin, but not CPT-11, was significantly reduced in parental p53(-/-) cells compared with parental p53(+/+) cells. These data suggest that p53 may be an important determinant of sensitivity to 5-FU and oxaliplatin but not CPT-11. Using semiquantitative reverse transcription-PCR, we have demonstrated down-regulation of thymidine phosphorylase mRNA in both p53(+/+) and p53(-/-) 5-FU-resistant cells, suggesting that decreased production of 5-FU active metabolites may be an important resistance mechanism in these lines. In oxaliplatin-resistant cells, we noted increased mRNA levels of the nucleotide excision repair gene ERCC1 and ATP-binding cassette transporter breast cancer resistance protein. In CPT-11-resistant cells, we found reduced mRNA levels of carboxylesterase, the enzyme responsible for converting CPT-11 to its active metabolite SN-38, and topoisomerase I, the SN-38 target enzyme. In addition, we noted overexpression of breast cancer resistance protein in the CPT-11-resistant lines. These cell lines are ideal tools with which to identify novel determinants of drug resistance in both the presence and absence of wild-type p53.
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PMID:Characterization of p53 wild-type and null isogenic colorectal cancer cell lines resistant to 5-fluorouracil, oxaliplatin, and irinotecan. 1504 37

We confirmed that the enzyme activity of thymidine phosphorylase (TP) can substitute for 5'-deoxy-5-fluorouridine (5'-dFUR) sensitivity in clinical colorectal cancer (CRC) tissues. Moreover, the idenfication of susceptible genes other than TP will be desired for prediction or treatment of 5'-dFUR. We initially established conditions for the MTT assay system in vivo to compare the growth inhibition rate and TP activity in 18 cases of CRC. TP activity levels were concordant with 5'-dFUR sensitivity in the CRCs (p<0.05). In 18 CRC cases, 4 cases of high sensitivity and 3 cases of low sensitivity to 5'-dFUR were compared to analyze expression profiles of 9437 genes on cDNA microarray chips. As a result, a cluster of genes related to the sensitivity were identified and another cluster of genes related to the insensitivity of 5'-DFUR were also listed. We determined that TP expression can precisely predict 5'-dFUR sensitivity in CRCs and found susceptibility related genes.
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PMID:Prediction of 5'-deoxy-5-fluorouridine sensitivity in colorectal cancer cases by thymidine phosphorylase activity and preliminary identification of susceptibility related genes. 1520 53

TAS-102 is a new antimetabolite agent composed of a alpha, alpha, alpha-trifluorothymidine (FTD; 1 M) and thymidine phosphorylase inhibitor (TPI; 0.5 M). Here, we investigated the antitumor effect and mechanism of TAS-102 against 5-FU, or FdUrd, resistant human cancer cell lines. The respective tumor growth inhibition rate of orally administered FTD against 5-FU-resistant NUGC-3 was about 70% at a dose level of 200 mg/kg/day; this value was comparable to that against the parental NUGC-3. On the other hand, the tumor inhibition rates of 5-FU, FdUrd, and TS-1 against 5-FU-resistant NUGC-3 were lower than those against parental NUGC-3. Similar observations were made in an FdUrd-resistant human colorectal cancer cell line (DLD-1). TAS-102 was also effective in 5-FU-less sensitive human pancreatic cancer cell lines (PAN-12 and BxPC-3) and human esophagus cancer (T.T.) when compared with 5-FU or UFT. Our hypothesis was that a relatively short and high dosage of TAS-102 results in an additional mechanism of FTD incorporation into DNA other than thymidylate synthase (TS) inhibition. We then examined the effects of FTD on DNA at the cellular level. After treatment with FTD or FdUrd, the DNA fragmentation pattern was examined using filter elution and in situ nick translation. Treatment with FTD for 2 h resulted in marked DNA fragmentation. When the tumor cells were treated with FTD for 72 h or with FdUrd for 2 or 72 h, only a small amount of DNA fragmentation was observed, and the appearance of the tumor cells did not differ markedly from that of untreated cells. Moreover, the DNA fragmentation rate in the TAS-102 treatment group was significantly higher than that in the control group in vivo. These results suggest that when tumor cells are exposed to high concentrations of FTD for short periods of time, FTD manifests its antitumor activity primarily through the induction of DNA fragmentation after FTD incorporation into the DNA. We conclude that TAS-102 is expected to manifest antitumor effects against 5-FU-resistant tumors that are similar to those exerted in 5-FU-sensitive tumors.
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PMID:A novel combination antimetabolite, TAS-102, exhibits antitumor activity in FU-resistant human cancer cells through a mechanism involving FTD incorporation in DNA. 1528 58

For the last four decades, synthesis and testing of potentially active drugs (e.g., antimetabolites) have focused on structural modification of existing metabolites as precursors of DNA and RNA synthesis. In recent years, the focus has shifted to synthesis of target-specific agents. Thus, the current emphasis of drug development is directed at inhibiting specific target(s) expressed preferentially, if not exclusively, in tumor tissues, with the ultimate goal of improving the therapeutic efficacy and selectivity of these new agents. Preclinically, proof-of-principle studies were carried out in tumors with specific expression of the intended target. With the hope of translating preclinical findings to the design of implementation of clinical trials. Thymidylate synthase (TS) continues to be a critical target for 5-fluorouracil (5-FU) and its prodrugs, UFT/LV (Orzel), capecitabine (Xeloda), and S-1, primarily because this enzyme is essential for the synthesis of 2-deoxythymidine-5-monophosphate, a precursor for DNA synthesis. While fluoropyrimidine antimetabolites have other sites of action, antifolates ZD1694 (raltitrexed, Tomudex) and AG337 (Thymitag) are more specific and potent TS inhibitors. Thus, it is hoped that pronounced and sustained inhibition of this enzyme could result in downstream regulation of molecular markers associated with sensitivity and resistance to these agents. It is also critical to recognize that the degree and duration of inhibition of the target enzyme may depend on the expression level of the target enzyme, thymidylate synthase. Correlative studies in preclinical and clinical systems demonstrated a close relationship between the enzyme level (mRNA and protein) and response to therapy of colorectal cancer patients treated with fluoropyrimidine or Tomudex. However, significant overlap was demonstrated between responders and non-responders. These data are consistent with the hypothesis that prediction of response to anticancer drugs is multifactorial, and TS is one target. Clinically, although overall response of colorectal cancer patients to a variety of TS inhibitors is similar, toxicity profiles are different. The availability of the 5-FU prodrugs offers the possibility of greater therapeutic selectivity based on the demonstration that thymidine phosphorylase, the activating enzyme for 5-FU, is expressed at a higher level in tumor tissue compared with normal tissue counterparts. It is likely that successful application of TS inhibitors will not only be based on measurement of the TS level in tumors vs. normal tissues, but on the delineation of the consequences of this inhibition on molecular markers associated with cellular proliferation, apoptosis and cell cycle regulation.
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PMID:Thymidylate synthase: a critical target in cancer therapy? 1535 99

We assessed the correlation among immunohistologically-stained nucleic acid metabolizing enzymes, such as thymidine phosphorylase (TP), thymidilate synthase (TS) and dehydropyrimidine dehydrogenase (DPD) detected in colorectal cancer patients, and the clinicopathologic factors, prognosis and efficacy of postoperative adjuvant chemotherapy. Results showed that TP staining positive cases had a higher incidence of vascular invasion and progression, and those with TS staining accounted for 30%. These cases also had lower 5-year survival rates. TS staining of 40% and DPD positive cases did not correlate with results shown in the TP positive and 30% TS staining group. Prognosis was better in patients who had undergone postoperative adjuvant chemotherapy and had negative DPD, TP and TS staining. These findings suggest that TP and TS are prognostic factors of colorectal cancer and that staining results of DPD combined with either TS or TP indicate the efficacy of postoperative adjuvant chemotherapy.
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PMID:[Prognosis and efficacy of postoperative adjuvant chemotherapy in colorectal cancer correlates with nucleic acid metabolizing enzymes]. 1544 56

The treatment of colorectal cancer has advanced over the past several years with the introduction of several active agents. Determining which patients to treat with chemotherapy and choosing optimal treatment would allow practioners to maximize the benefit of chemotherapy. Several prognostic and predictive markers have been identified and include oncogenes, tumor suppressor genes, genes involved in angiogenic and apoptotic pathways and cell proliferation, and those encoding targets of chemotherapy. Specifically, prognostic markers include deletion of 18q (DCC), p27 and microsatellite instability. Predictive markers are those that may determine efficacy of drugs used in colorectal cancer such as fluropyrimidines and oxaliplatin. Alterations in gene expression, protein expression and polymorphic variants in genes encoding thymidylate synthase, dihydropyrimidine dehydrogenase, and thymidine phosphorylase and excision repair cross-complementing genes (ERCC1) may be useful as markers for clinical drug response, survival and host toxicity. The integration of these prognostic and predictive markers would allow individualized treatment for patients, maximizing therapeutic effect and minimizing exposure to toxicity.
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PMID:Tailored chemotherapy for colorectal cancer: a new approach to therapy. 1558 Oct 57

Xeloda (Capecitabine), a prodrug of antitumor agent 5-fluorouracil, is the first and only oral fluoropyrimidine to be approved for use as second-line therapy in metastatic breast cancer, colorectal cancer, and other solid malignancies. Fluorine-18 labeled Xeloda may serve as a novel radiotracer for positron emission tomography (PET) to image enzymes such as thymidine phosphorylase and uridine phosphorylase in cancers. The precursor 2',3'-di-O-acetyl-5'-deoxy-5-nitro-N(4)-(pentyloxycarbonyl)cytidine (11) was synthesized from D-ribose and cytosine in 8 steps with approximately 18% overall chemical yield. The reference standard 5'-deoxy-5-fluoro-N(4)-(pentyloxycarbonyl)cytidine (Xeloda; 1) was synthesized from D-ribose and 5-fluorocytosine in eight steps with approximately 28% overall chemical yield. The target radiotracer 5'-deoxy-5-[(18)F]fluoro-N(4)-(pentyloxycarbonyl)cytidine ([(18)F]Xeloda; [(18)F]1) was prepared by nucleophilic substitution of the nitro-precursor with K(18)F/Kryptofix 2.2.2 followed by a quick deprotection reaction and purification with the HPLC method in 20-30% radiochemical yields.
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PMID:Synthesis of [18F]Xeloda as a novel potential PET radiotracer for imaging enzymes in cancers. 1560 85

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