Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A thymidylate synthase (TS)-ribonucleoprotein (RNP) complex composed of TS protein and the mRNA of the tumor suppressor gene p53 was isolated from cultured human colon cancer cells. RNA gel shift assays confirmed a specific interaction between TS protein and the protein-coding region of p53 mRNA, and in vitro translation studies demonstrated that this interaction resulted in the specific repression of p53 mRNA translation. To demonstrate the potential biological role of the TS protein-p53 mRNA interaction, Western immunoblot analysis revealed nearly undetectable levels of p53 protein in TS-overexpressing human colon cancer H630-R10 and rat hepatoma H35(F/F) cell lines compared to the levels in their respective parent H630 and H35 cell lines. Polysome analysis revealed that the p53 mRNA was associated with higher-molecular-weight polysomes in H35 cells compared to H35(F/F) cells. While the level of p53 mRNA expression was identical in parent and TS-overexpressing cell lines, the level of p53 RNA bound to TS in the form of RNP complexes was significantly higher in TS-overexpressing cells. The effect of TS on p53 expression was also investigated with human colon cancer RKO cells by use of a tetracycline-inducible system. Treatment of RKO cells with a tetracycline derivative, doxycycline, resulted in 15-fold-induced expression of TS protein and nearly complete suppression of p53 protein expression. However, p53 mRNA levels were identical in transfected RKO cells in the absence and presence of doxycycline. Taken together, these findings suggest that TS regulates the expression of p53 at the translational level. This study identifies a novel pathway for regulating p53 gene expression and expands current understanding of the potential role of TS as a regulator of cellular gene expression.
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PMID:Thymidylate synthase protein and p53 mRNA form an in vivo ribonucleoprotein complex. 989 Oct 91

OGT 719 is a novel p.o. bioavailable nucleoside analogue in which galactose is incorporated onto the fluoropyrimidine moiety of the cytotoxic agent 5-fluorouracil (5-FU). OGT 719 has been designed to reduce the systemic toxicity normally associated with 5-FU while retaining activity against disease localized in the liver, in which it may be preferentially localized through the asialoglycoprotein receptor (ASGP-R). We report studies confirming the activity of OGT 719 in inhibiting growth of metastatic human colorectal tumors in the liver of nude mice. The human colorectal cancer cell line C170HM2 readily forms liver metastases in vivo. Oral administration of 1500 mg/kg/day OGT 719 inhibited liver tumor burden by 95% compared with vehicle control, without any observable signs of toxicity. When the tumor burden was increased and the same OGT 719 treatment was compared with a standard clinical dose regimen of 25 mg/kg/day 5-FU/leucovorin given i.v., both treatments were equally efficacious, although 5-FU/leucovorin treatment started 7 days earlier. In contrast to 5-FU, OGT 719 is p.o. bioavailable and has a plasma half-life between 1.5 and 3 h. Several colorectal cancer cell lines express the asialoglycoprotein receptor, although no significant levels can be detected in C170HM2 cells, consistent with the observation that OGT 719 is approximately 3 log orders of magnitude less potent in vitro than 5-FU. Flux through thymidylate synthase, as measured by 3H release from [3H]dUrd, was inhibited by OGT 719 at 4 h. The notable difference in the potency of OGT 719 efficacy on C170HM2 cells in vitro and in vivo supports our model of liver-specific activation of OGT 719. As our data suggest, OGT 719 may significantly inhibit growth of metastatic colorectal tumors in the liver in vivo. This hypothesis is presently being explored in clinical trials for primary hepatocellular carcinoma and colorectal liver metastases.
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PMID:A novel, orally administered nucleoside analogue, OGT 719, inhibits the liver invasive growth of a human colorectal tumor, C170HM2. 1009 58

The synergistic mechanism of cisplatin (CDDP) and 5-fluorouracil (5-FU) in combination remains unclear, despite its substantial antitumor activity, which has been demonstrated clinically. To clarify the mechanism(s), we determined the sensitivity or resistance factors to either drug in seven gastrointestinal cancer cell lines and then analyzed the altered gene expression after different exposures to CDDP and 5-FU. At the basal gene expression level, glutathione S-transferase pi (GSTpi) expression correlated with the observed resistance to CDDP, whereas dihydropyrimidine dehydrogenase (DPD) and multidrug resistance-associated protein (MRP) expression was related to 5-FU resistance. GSTpi, DPD, and MRP expression increased in response to the respective drug, but they also increased in response to the other drug as well. Additionally, 5-FU revealed a drastically increased thymidylate synthase (TS) gene expression in 5-FU-resistant cells. However, the increasing actions of CDDP and 5-FU on GSTpi, DPD, MRP, and TS expression varied according to the exposure time, concentration, and schedule. A low concentration of CDDP (1 microg/ml, 30 min) followed by 5-FU (0.5 microg/ml, 72 h) was found to cause a less increased expression of DPD, MRP, GSTpi, and TS than either drug alone, thus resulting in synergistic cytotoxicity in 5-FU-resistant COLO201 and CDDP-resistant HCC-48 cells. The sequential combination of CDDP and 5-FU inhibited the growth of human normal renal proximal tubule cells by less than 20%. Low concentrations of CDDP followed by continuous exposure to 5-FU can repress increased gene expression related to both drug resistances, thereby being synergistically cytotoxic in human gastrointestinal cancer cells.
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PMID:Low-dose cisplatin and 5-fluorouracil in combination can repress increased gene expression of cellular resistance determinants to themselves. 1049 41

2-Deamino-2-methyl-N10-propargyl-5,8-dideazafolic acid (ICI 198583) is a potent inhibitor of thymidylate synthase. Its analogue, N(alpha)-[4-[N-[(3,4-dihydro-2-methyl-4-oxo-6-quinazolinyl)methyl]-N-propargylamino]phenylacetyl]-L-glutamic acid, containing p-aminophenylacetic acid residue substituting p-aminobenzoic acid residue, was synthesized. The new analogue exhibited a moderately potent thymidylate synthase inhibition, of linear mixed type vs. the cofactor, N(5,10)-methylenetetrahydrofolate. The Ki value of 0.34 microM, determined with a purified recombinant rat hepatoma enzyme, was about 30-fold higher than that reported for inhibition of thymidylate synthase from mouse leukemia L1210 cells by ICI 198583 (Hughes et al., 1990, J. Med. Chem. 33, 3060). Growth of mouse leukemia L5178Y cells was inhibited by the analogue (IC50 = 1.26 mM) 180-fold weaker than by ICI 198583 (IC50 = 6.9 microM).
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PMID:Synthesis and biological activity of N(alpha)-[4-[N-[(3,4-dihydro-2-methyl-4-oxo-6-quinazolinyl)methyl]-N-propargylamino]phenylacetyl]-L-glutamic acid. 1213 41

We developed an original in vitro model dedicated to the exploration of molecular pharmacology of the new oral fluoropyrimidine capecitabine (Xeloda). More specifically, in this report, we investigated whether apoptosis induced by capecitabine was mediated by the Fas/FasL system. To achieve this goal, a specific in vitro coculture model mixing hepatoma and human colorectal cell line was used. A bystander effect was observed between HepG2 and LS174T cells treated with capecitabine. Besides this, Xeloda showed a 7-fold higher cytotoxicity and markedly stronger apoptotic potential in thymidine phosphorylase (TP)-transfected LS174T-c2 cells. The striking enhancement of thymidylate synthase inhibition that we observed in cells with high TP activity was most probably at the origin of the potentiation of capecitabine antiproliferative efficacy. In addition, this increase of sensitivity was accompanied by a strong overexpression of the CD95-Fas receptor on the cell surface. Both Fas and FasL mRNA expression were triggered after exposing TP+ cells to the drug. This implication of Fas in Xeloda-induced apoptosis was next confirmed by using antagonistic anti-Fas and anti-FasL antibodies that proved to reverse capecitabine antiproliferative activity, thus highlighting the key role that Fas could play in the optimization of an antitumor response to fluoropyrimidine drugs. Our data, therefore, show that TP plays a key role in the capecitabine activity and that the Fas/FasL system could be considered as a new determinant for Xeloda efficacy.
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PMID:Transmission of apoptosis in human colorectal tumor cells exposed to capecitabine, Xeloda, is mediated via Fas. 1248 13

To investigate the effect of biochemical modulation on antitumor activity shown by the combination of 5-Fluorouracil (5-FU) and interferon-alpha (IFN-alpha), experimental therapy was performed on human hepatocellular carcinoma cell (HuH7, PLC/PLF/5) xenografts inoculated into nude mice, using 5-FU and IFN-alpha, either alone or in combination. These agents showed antitumor activity in different degrees. Although IFN-alpha, given as 100,000 units/mouse/3 times/week subcutaneously x 6, and 5-FU, given as 0.5 mg/mouse/3 times/week intraperitoneally, showed addititive antitumor effect against HuH7 and PLC/PLF/5, the activities of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), thymidine phosphorylase (TP), orotate phosphoribosyltransferase (OPRT), uridine phosphorylase (UP) and uridine kinase (UK) were not significantly influenced in the tumors treated with the 5-FU/IFN-alpha combination, compared with those treated with 5-FU or IFN-alpha alone. This suggested that antitumor activity of 5-FU and IFN-alpha in combination was not significantly involved in 5-FU metabolism in two human hepatocellular carcinoma cell lines examined.
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PMID:[Influence on 5-fluorouracil metabolism by combination of interferon-alpha and 5-fluorouracil against human hepatocellular carcinoma xenografts]. 1550 42

The combination of epirubicin, cisplatin, and protracted venous-infusion 5-fluorouracil is the standard treatment of advanced gastric carcinoma in many European countries, and it is also an active regimen in hepatobiliary tumors. Raltitrexed is a specific inhibitor of thymidylate synthase with clinical activity in gastrointestinal malignancies. The aim of the study was to evaluate the clinical activity and toxicity of the combination of epirubicin, cisplatin, and raltitrexed in patients with advanced gastric and hepatobiliary tumors. Twenty consecutive patients with gastric carcinoma, 7 with biliary-tract carcinoma, and 5 patients with hepatocarcinoma were treated with epirubicin (60 mg/m2), cisplatin (60 mg/m2) on day 1, and raltitrexed (1 mg/m2) on days 1 and 8, every 3 weeks. The median age was 63 years (range, 28-76). Eight patients had locally advanced disease and 24 had metastatic tumors. Seven of the 18 evaluable patients (39%) with gastric carcinoma and 2 of the 5 patients with hepatocarcinoma have a partial response; 1 minimal response and 4 stabilization of disease were documented in the 7 patients with biliary-tract carcinoma. The median time to progression of the entire group was 6.8 months, and the median survival was 9.0 months. The toxicity was mild and no toxic death occurred. The combination of epirubicin, cisplatin, and raltitrexed, using this schedule, is tolerable and has clinical activity in gastric and hepatobiliary tumors.
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PMID:Epirubicin, cisplatin, and raltitrexed in patients with advanced gastric and hepatobiliary carcinoma: a phase II study. 1559 7

The inhibition of thymidylate synthase (TS) by 5-fluorouracil (5-FU) was known to increase the incorporation of radiolabelled iododeoxyuridine (IdUrd) into DNA. The relatively non-toxic compounds such as thiol-containing antioxidant pyrrolidinodithiocarbamte (PDTC) or aromatic fatty acid phenylbutyrate (PB) had been reported to enhance the cytotoxic efficacy of 5-FU. We designed a novel strategy through triplet combination of PB, PDTC and 5-FU to increase the radiolabelled IdUrd uptake and investigated the underlying mechanisms. The growth inhibition and [(125)I]IdUrd-DNA incorporation by PB, PDTC, 5-FU in different combinations were tested on parent or p21(Waf1) transfected Hep3B cells. The combination of PB and PDTC was more effective in enhancing 5-FU cytotoxicity than either drug alone. The combination of PB/PDTC and 5-FU blocked cells in S-phase and resulted in 8.5-fold increase of radiolabelled IdUrd-DNA incorporation. The transfection of p21(Waf1) did not change the general pattern of enhancement. Intriguingly, the combination of PB and PDTC effectively down-regulated NF-kappaB and TS and prevented their up-regulation from 5-FU treatment than either drug alone through a p21(Waf1)-independent mechanism. Based on this strategy, the 3-drug combination offered potential for improved radiolabelled IdUrd molecular radiotherapy for hepatoma treatment.
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PMID:Modulation of 5-fluorouracil cytotoxicity through thymidylate synthase and NF-kappaB down-regulation and its application on the radiolabelled iododeoxyuridine therapy on human hepatoma cell. 1567 May 80

Fluoropyrimidines [5-Fluorouracil (5-FU) and its prodrugs] have been widely used in the treatment of solid cancers. The anticancer effects primarily depend on intratumoral levels of enzymes metabolizing the drugs, such as dihydropyrimidine dehydrogenase (DPD), orotate phosphoribosyltransferase (OPRT), thymidine phosphorylase (TP), and thymidylate synthase (TS). In order to know the tumor types susceptible to respective fluoropyrimidines, we investigated the expression of DPD, OPRT, TP and TS in various types of cancer with the immunoperoxidase method. These four enzymes existed in all of the cancer types studied, such as pulmonary, gastric, colorectal, hepatic, cholecystic, pancreatic, renal, urocystic, and mammary cancers. Respective types of cancers presented characteristic immunohistochemical features as follows: pulmonary adenocarcinoma, DPD- and TP-high; pulmonary squamous cell carcinoma, TS- and TP-high; intestinal-type gastric adenocarcinoma, TP-high; diffuse-type gastric adenocarcinoma, DPD-low and TS-high; colorectal adenocarcinoma, DPD- and TP-low, hepatocellular carcinoma, DPD-high, and TS- and OPRT-low; cholecystic adenocarcinoma, DPD- and TS-high; renal cell carcinoma, DPD-low, and OPRT- and TP-high; urocystic transitional cell carcinoma, DPD-high and OPRT-low; and mammary ductal carcinoma, OPRT-low, and TS- and TP-high. The enzyme expression pattern in cancer tissue was generally similar to that of their normal counterparts. However, TP immunoreactivity in adenocarcinomas of the lung, stomach and gallbladder, and urothelial carcinoma of the urinary bladder was stronger, and DPD immunoreactivity in adenocarcinoma of the breast was weaker, when compared with normal epithelial cells. Non-epithelial cells were also positive for these enzymes. These results indicated that the key enzymes influencing the effects of fluoropyrimidines differ from cancer to cancer. Fluoropyrimidine treatment may be selected, based on the simultaneous immunohistochemical evaluation of the fluoropyrimidine metabolic enzymes.
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PMID:Immunohistochemical demonstration of fluoropyrimidine-metabolizing enzymes in various types of cancer. 1621 Dec 89

Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme in the catabolism of 5-fluorouracil (5-FU) and its activity is closely associated with cellular sensitivity to 5-FU. This study examines the role of DPD in the antiproliferative effects of 5-FU combined with IFN-alpha on hepatocellular carcinoma (HCC) cells in culture and asks whether IFN-alpha could affect DPD expression. The combined action of IFN-alpha and 5-FU on three HCC lines was quantified by a combination index method. Coadministration of IFN-alpha and 5-FU showed synergistic effects against HAK-1A and KYN-2 but antagonistic effects against KYN-3. The cellular expression levels of DPD mRNA and protein were markedly up-regulated in KYN-3 cells by IFN-alpha but were down-regulated in HAK-1A and KYN-2. The expression of thymidylate synthase mRNA and protein was down-regulated by IFN-alpha in all three cell lines. Coadministration of a selective DPD inhibitor, 5-chloro-2,4-dihydroxypyridine (CDHP), enhanced the antiproliferative effect of 5-FU and IFN-alpha on KYN-3 approximately 4-fold. However, the synergistic effects of 5-FU and IFN-alpha on HAK-1A and KYN-2 were not affected by CDHP. The antiproliferative effect of 5-FU could thus be modulated by IFN-alpha, possibly through DPD expression, in HCC cells. Inhibition of DPD activity by CDHP may enhance the efficacy of IFN-alpha and 5-FU combination therapy in patients with HCC showing resistance to this therapy.
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PMID:Alteration of dihydropyrimidine dehydrogenase expression by IFN-alpha affects the antiproliferative effects of 5-fluorouracil in human hepatocellular carcinoma cells. 1769 26


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