Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024623 (gastric cancer)
 36,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We evaluated antitumor effect histologically and assayed the tissue levels of 5-fluorouracil (5-FU) and thymidylate synthase (TS) activity using surgical specimens obtained from the patients with rectal cancer, who were given tegafur suppositories prior to surgery. The antitumor effect was evaluated histologically according to classification of the general rules for the gastric cancer study (Japanese Research Society for Gastric Cancer). In 39 patients, 16 tumor specimens revealed no effect (grade-0), 22 tumors grade-1 effect, and one was not evaluable because of the severe inflammatory changes. In 23 of these patients, resected specimens were available for the assay. 5-FU levels in cancer tissues were significantly higher than those in normal tissues, and TS inhibition rates (TSIR) were almost identical, averaging around 20%, in both cancer and normal tissues. Comparing the 5-FU levels and TS activity according to the histological effects (i.e.: 'grade-0' vs 'grade-1'), the 5-FU levels in the tumors achieved grade-1 were significantly higher than in the tumors showed 'grade 0' (p less than 0.01), and TSIR in the former were relatively greater than in the latter (p = 0.053). It is suggested that both tissue levels of 5-FU and TSIR may be useful parameters to predict the anti-tumor effect against rectal cancer after administration of 5-FU and its derivatives.
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PMID:[Neo-adjuvant chemotherapy with tegafur suppository for rectal cancer--evaluation of the antitumor effects, tissue levels of 5-FU and inhibition of thymidylate synthase. Tochigi Colorectal Cancer Study Group]. 151 26

Leucovorin (LV), given intravenously the orally becomes 5, 10-methylene tetrahydrofolate in both cancer and normal cells. FdUMP which is an active metabolite of 5-FU binds tightly to thymidylate synthase in the presence of the cofactor 5, 10-methylene tetrahydrofolate. This interaction leads to potentiate the cytotoxic effect of 5-FU by prolonged inhibition of thymidylate synthase. Clinically, the combination of LV and 5-FU is given parenterally by two schedules; 5 consecutive days schedule and weekly schedule. Five 5 consecutive days-schedule is divided into 2 methods. One is a 200 mg/m2/day of LV by Machover, and the other is 20 mg/m2/day of LV by O'Connell. The weekly schedule is a 2-hour infusion of dl-LV (500 mg/m2) and iv bolus of 5-FU (600 mg/m2), given 1 hour after the beginning of LV infusion by Petrelli. A multicenter cooperative study in Japan was conducted to evaluate the clinical efficacy of LV and 5-FU using the weekly schedule by Petrelli. Response rates were 31.5% and 41.2% against advanced gastric and colorectal cancer respectively. Then, we carried out a randomized early phase II study using 250 mg/m2 of l-LV weekly (similar to the schedule of Petrelli's, armA) and 100 mg/m2 (similar to the schedule of Machover's, arm B) or 10 mg/m2 (similar to the schedule of O'Connell's, arm C) of l-LV for 5 consecutive days against gastric cancer. The response rate was 33.3% in arm A, 24.1% in arm B and no response in arm C. Toxicity was within acceptable limits, Toxic effects included diarrhea, stomatitis, anorexia and myelohypoplasia. Our data suggests that high-dose LV and 5-FU seems to be a very promising combination but, there was no responder using low dose (10 mg/m2) of l-LV schedule against gastric cancer patients.
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PMID:[High-dose leucovorin and 5-FU]. 162 51

In recent years the concept of metabolic modulation of fluoropyrimidines by leucovorin has been introduced clinically in patients with advanced colorectal cancer, breast cancer, gastric cancer and head and neck cancer among others. The concept of metabolic modulation was developed in the laboratory and employed clinically. Leucovorin is a noncytotoxic compound used to increase the therapeutic efficacy of 5-fluorouracil. Following 5-fluorouracil activation to 5-fluorodeoxyuridine monophosphates, its binding to thymidylate synthase is stabilized by the active cofactor, 5,10 methylene tetrahydrofolate and its polyglutamate forms. Under these conditions, both the extent and duration of inhibition of thymidylate synthase and consequently, DNA synthesis are more pronounced. The results of clinical trials (phase II and III) indicate that the response rates to 5-fluorouracil/leucovorin modulation are significantly higher than that of fluorouridine alone.
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PMID:Modulation of fluoropyrimidines by leucovorin: rationale and status. 183 38

The effects of preoperative treatment by continuous intravenous infusion of Tegafur, the antagonist of DNA synthesis, were histopathologically studied in 34 patients with gastric cancer. Histologically the treatment was found to be effective in 41.2% of patients with cancer invasion in the mucosa, 58.8% in the submucosa, 61.3% in the muscularis propria, 59.3% in the subserosa and 86.9% of those with metastatic lymph nodes. The treatment was effective, when assessed in terms of the histological type of cancer, in 90.9% of cancers of the differentiated type (papillary adenocarcinoma, well differentiated tubular adenocarcinoma and moderately differentiated tubular adenocarcinoma) and 47.8% of those of the poorly differentiated type (poorly differentiated adenocarcinoma, mucinous adenocarcinoma and signet-ring cell carcinoma), showing a higher rate of efficacy in the differentiated type cancers. Meanwhile, even among patients with cancer of poorly differentiated type, a high efficacy rate (90.0%) was found in those with metastatic cancer of the lymph nodes. No relationship was found between the total doses of Tegafur and histological effects. There was a tendency, however, for a higher frequency of a good response in patients administered more than 4,000 mg of Tegafur. In the patients with a histologically positive effect, 5-FU concentration in the tumor tissue was higher than 0.071 microgram/g. However, some patients showed no response despite a high concentration. This finding suggested that sensitivity to 5-FU and 5-FU metabolism vary depending on the tumor. The inhibitory effect of Tegafur on DNA synthesis is produced through inhibition of thymidylate synthase (TS) by the Tegafur metabolite FdUMP.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Histopathological studies on antitumor effect of tegafur administered by continuous intravenous infusion]. 211 40

The authors examined the relationship between the level of thymidylate synthase (TS) and the sensitivity to 5-fluorouracil (5-FU) and UFT, a combined oral preparation of 1-(2-tetrahydrofuryl)-5-fluorouracil (tegafur) and uracil in a molar ratio of 1:4. For the studies we used the subrenal capsule (SRC) assay and 15 human gastric cancer tissues. The TS levels were assayed by the ligand-binding technique, using [6-3H]FdUMP. The relative variation of tumor size (delta TuS/TuS0) was calculated to be as follows: delta TuS/TuS0 = [(TuS6 - TuS0)/TuS0] x 100 (%), where TuS6 was the tumor size on day 6 and TuS0 on day 0. The chemosensitivity was considered to be positive when delta TuS/TuS0 in the treated group decreased to below -10%. Decrease in tumor size was marked in case of exposure to UFT (-19.8 +/- 13.0%) (mean +/- standard deviation), compared with that to 5-FU (-9.0 +/- 7.2%), with a statistically significant difference (P less than 0.001). The TS level varied from 1.7 to 30.8 pmol/g gastric cancer tissue and the mean was 7.1 +/- 7.2 pmol/g tissue. A correlation was noted between the TS level and decrease in size of the tumor exposed to 5-FU (r = -0.671) or UFT (r = -0.758): gastric cancer tissue with higher level of TS is more sensitive to 5-FU and UFT than is that with a lower TS level. These findings show that the sensitivity to 5-FU and UFT of gastric cancer tissue is related to the TS level and that UFT shows promise for the treatment of patients with gastric cancer.
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PMID:5-Fluorouracil and UFT-sensitive gastric carcinoma has a high level of thymidylate synthase. 249 66

Pre-operative chemotherapy with concomitant use of UFT and CDDP (UFT: oral administration of 400 mg/day for 2 weeks till one day before operation, CDDP, one intravenous drip of 40 mg/m2 one week before operation) was used for 24 untreated cases of advanced stomach cancer diagnosed as resectable pre-operatively, and the histological antitumor effect analyzed in dissected preparation and the thymidylate synthase inhibition rate (TSIR: %) in tumor tissue were examined. The average administration dose of CDDP was 61.1 mg/body, and the average total administration dose of UFT was 5.0 g/body. The histological antitumor effect was grade 0 in 8 cases (33.3%), grade 1a in 10 cases (41.7%), grade 1b in 5 cases (20.8%), and grade 2 in 1 case (4.2%). TSIR in tumor tissue was under 10% in 2 cases (9.1%); over 10% and under 20% in 4 cases (18.2 %); over 20% and under 30% in 6 cases (27.3%); over 30% and under 40% in 5 cases (22.7%); over 40% and under 50% in 3 cases (13.6%); over 50 % in 2 cases (9.1%), and not measurable in 2 cases, with the average of 29.0%. The correlation was observed between histological anti-tumor effect and TSIR in tumor tissue (p < 0.05). These results suggest the possibility that the anti-tumor effect can be estimated at the in vivo level from measurement of TSIR in tumor tissue.
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PMID:[UFT/CDDP preoperative chemotherapy for progressive gastric cancer--histological antitumor effects and thymidylate synthase inhibition rate]. 748 25

Methionine-depleting total parenteral nutrition (Met-depleting TPN), infusing AO-90 amino acid solution (lacking both L-methionine and L-cysteine) as a sole nitrogen source, showed synergistic effects with 5-fluorouracil (5-FU) in tumor-bearing rats and in clinical trials with gastrointestinal tract cancers. In this study, the effect of Met-depleting TPN with 5-FU upon thymidylate synthase (TS) activity was examined, and the histological effect of this treatment on human gastric cancer was evaluated. Fourteen preoperative advanced gastric cancer patients were divided randomly into two groups. Seven cases were given Met-depleting TPN for 7 days before surgery with continuous intravenous administration of 5-FU (500 mg/body per day; total 4.0 g/body) (AO-90 group). The other 7 received conventional L-methionine-containing TPN with 5-FU (control group). All patients underwent gastrectomy without complications due to these treatments. Resected materials were examined for TS kinetics, and the anti-cancer effect was also assessed histopathologically. The specimens in the AO-90 group showed marked degeneration of cancer, while almost no effect was seen in the control group. The free TS activity of carcinoma tissue in the AO-90 group was decreased and the TS inhibition rate was increased in comparison with the control group (P = 0.0165 and P = 0.0243, respectively). Met-depleting TPN appears to play a role as a biomodulator of 5-FU in human gastric cancer.
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PMID:Synergistic effect of methionine-depleting total parenteral nutrition with 5-fluorouracil on human gastric cancer: a randomized, prospective clinical trial. 779 Mar 21

5-fluorouracil (5-FU)/methotrexate (MTX) sequential chemotherapy is one of the standard regimen for the treatment of gastric cancer. Though this combination therapy is highly effective, the mechanism is still unclear. In this study, we investigated the relationship between antitumor activity and the inhibition of thymidylate synthase and between antitumor activity and incorporation of 5-FU into RNA (F-RNA) in mice bearing Sarcoma-180 treated by tegafur alone (100 mg/kg) or by the combination of MTX (42 mg/kg) and tegafur (100 mg/kg). A new method for the determination of F-RNA of tumor tissue samples was used. Briefly, RNA fractions containing incorporated 5-FU were extracted by KOH hydrolysis. FUra in RNA fractions was released by HCl hydrolysis and its levels were determined by GC-MS. The results showed that the F-RNA levels were significantly elevated by the pretreatment of MTX. According to this result, it is suggested that the measurement of F-RNA levels together with the determination of FUra concentration and the inhibition rate of thymidylate synthase were considered as a good means for the evaluation of antitumor efficacy of FUra. We concluded that the impairment of RNA metabolism played a major role in the antitumor activity of MTX/5-FU combination.
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PMID:[The mechanism of biochemical modulation in methotrexate/5-fluorouracil sequential chemotherapy]. 797 18

The mechanism of resistance to 5-fluorourcil (5-FU) was studied with NUGC-3/5FU/L, a human stomach cancer cell line which had acquired resistance as a consequence of repeated 5-day exposures to stepwise-increasing concentrations of 5-FU in vitro. NUGC-3/5FU/L was 200-fold and over 16-fold resistant to 96-h and 1-h exposures to 5-FU, respectively. NUGC-3/5FU/L incorporated less 5-FU into RNA, indicating resistance to the RNA-directed action of 5-FU. On the other hand, NUGC-3/5/5FU/L also showed resistance to in situ thymidylate synthase (TS) inhibition by 5-FU. Polymerase chain reaction-single-strand conformation polymorphism analysis of TS cDNA and a FdUMP ligand binding assay showed that quantitative and qualitative alterations of TS are not responsible for this resistance. In contrast, the ability to metabolize 5-FU to its active metabolites, FUTP and FdUMP, was reduced in NUGC-3/5FU/L. We found that not only the activities of uridine phosphorylase/kinase and orotate phosphoribosyl-transferase (OPRT), but also the level of phosphoribosyl pyrophosphate, a cosubstrate for OPRT, were significantly lower in NUGC-3/5FU/L than in the parent NUGC-3. These results indicated that resistance to 5-FU in NUGC-3/5FU/L is due to reduced activities of 5-FU-anabolizing enzymes, but not to an alteration of TS. 2'-Deoxyinosine effectively enhanced TS inhibition by 5-FU in the resistant cells, thus markedly sensitizing them to 5-FU.
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PMID:Reduced activity of anabolizing enzymes in 5-fluorouracil-resistant human stomach cancer cells. 860 72

Currently, biochemical modulation for 5-fluorouracil (5-FU) by cisplatin (CDDP) is one of the most successful forms of chemotherapy for gastric cancer. Although the mechanism of this modulation is thought to increase intracellular folate levels, it is still unknown how much CDDP is needed to elevate folate levels. The purpose of this study is to determine the appropriate volume of CDDP as a modulator for 5-FU. Either 5, 20, 100 mg/body of CDDP was administered intravenously to advanced gastric cancer patients just before operation. Four hrs later, the stomach was resected and folate levels were measured in the tumor and normal mucosa by thymidylate synthase binding assay. The results showed folate elevation only after administration of 100 mg/body of CDDP, both in the tumor and mucosa (p < 0.01). In conclusion, if CDDP is infused as a bolus, a relatively large amount is needed to modulate the intratumor folate level.
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PMID:[Changes in folate levels after cisplatin treatment of gastric cancer]. 867 15


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