Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P17174 (aspartate aminotransferase)
 14,872 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Induction of replicative DNA synthesis (RDS) and mitoinhibitory effects were studied in the hepatocytes of F344 rats exposed in vivo to the methylating agents dimethylnitrosamine (DMN, hepatocarcinogen) and methylnitrosourea (MNU, non-hepatocarcinogen). Cytotoxicity and chromosome aberrations (CA) in rat liver were also investigated to clarify the cause of changes in RDS and mitoinhibitory effects, respectively. The animals were killed at different intervals (up to 14 days) after a single oral dose, or 1 day after 7 or 14 days of repeated oral doses. The hepatocytes were isolated and cultured with Williams' medium E to assess their RDS, mitoinhibitory effects and CA. Mitoinhibitory effects were investigated by monitoring their effect on epidermal growth factor-induced replicative DNA synthesis (EGF-induced RDS) in rat hepatocytes. Hepatotoxic effects were assessed by measuring aspartate transaminase and alanine transaminase in the plasma and by histopathological examination. In the single-dose study, DMN (20 mg/kg body weight (bw)) induced both RDS and hepatotoxicity. MNU (50 mg/kg bw) induced RDS without causing hepatotoxicity, and thus was classified as a mitogen. In the repeated-dose study, DMN (4 mg/kg bw) induced both RDS and hepatotoxicity, but MNU (10 mg/kg bw) induced neither. Both inhibition of EGF-induced RDS and induction of CA were observed in the hepatocytes of rats treated with DMN, but were not observed with MNU in both single and repeated dose studies. The mitoinhibitory effect of DMN persisted for 14 days after the single dose and time dependently increased for 14 days after repeated administration. This mitoinhibitory effect correlated positively with CA. The mitoinhibitory effect was thought to be attributable to the DNA-damaging effect that induces CA. We concluded that the differences which we found in this study between DMN and MNU contribute to the differences in their hepatocarcinogenicity. Our findings suggested that both cell proliferative and mitoinhibitory properties play an important role in tumor promotion, and measuring them may provide an ancillary index that is useful in predicting hepatocarcinogenicity.
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PMID:A short-term assessment of tumor-promotion activity in the livers of rats treated with two genotoxic methylating agents: dimethylnitrosamine and methylnitrosourea. 978 84

The indolizidine alkaloid swainsonine, a potent inhibitor of Golgi alpha-mannosidase II, has been shown to reduce tumor cell metastasis, enhance cellular immune responses, and reduce solid tumor growth in mice. In our previous Phase I study, swainsonine administered by 5-day continuous infusion inhibited L-phytohemagglutinin-reactive N-linked oligosaccharide expression on peripheral blood lymphocytes. Significant toxicities included edema and elevated serum aspartate aminotransferase (AST). One patient with head and neck cancer had objective (>50%) tumor remission. Two patients showed symptomatic improvement. The objectives of this Phase IB trial were to examine the pharmacokinetics, toxicities, and biochemical effects of bi-weekly oral swainsonine at escalating dose levels (50-600 microgram/kg) in 16 patients with advanced malignancies and 2 HIV-positive patients unsuitable for conventional therapy. Eastern Cooperative Oncology Group performance status was </=2. The maximum tolerated dose was defined as 300 microgram/kg/day due primarily to serum AST abnormalities and dyspnea. Other adverse events present in >20% of patients included increase in serum AST (all patients), fatigue (n = 9), anorexia (n = 6), dyspnea (n = 6), and abdominal pain (n = 4). Inhibition of Golgi alpha-mannosidase II occurred in a dose-dependent manner. Examination of immunological parameters revealed a transient decrease in CD25(+) peripheral blood lymphocytes and, in seven of eight patients, an increase in CD4(+):CD8(+) ratios at 2 weeks. Serum drug levels peaked 3-4 h following a single oral dose in most patients and were proportional to dose at levels >/=150 microgram/kg. We conclude that oral swainsonine is tolerated by chronic intermittent administration at doses up to 150 microgram/kg/day. Adverse events considered drug related were similar to those observed in the infusional study but with fatigue and neurological effects also noted. Investigations of alternative dosing schedules with low starting doses are suggested for further clinical testing.
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PMID:Phase IB clinical trial of the oligosaccharide processing inhibitor swainsonine in patients with advanced malignancies. 981 86

The interaction between glycolysis, glutaminolysis and tumor growth in WAG/Fra rnu/rnu rats has been investigated. Small tumors are characterized by a low conversion of glucose to lactate whereas the conversion of glutamine to lactate is high. In medium sized tumors the flow of glucose to lactate as well as oxygen utilization are increased whereas glutamine and serine consumption are reduced. At this stage the tumor cells start with glutamate and alanine production. Large tumors are characterized by a low oxygen and glucose supply but a high glucose and oxygen utilization rate. The conversion of glucose to glycine, alanine, glutamate, glutamine, and proline reaches high values and the amino acids are released. Pyruvate kinase increases with tumor weight and is positively correlated with an increase in glucose and oxygen utilization. The shift from glutamate consumption to glutamate production is correlated with an increase in glutamate dehydrogenase and glutamate oxaloacetate transaminase activity.
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PMID:Pyruvate kinase and the interaction of amino acid and carbohydrate metabolism in solid tumors. 985 94

Natural products from plants are rich sources used for treating a number of diseases. Many of the pharmacological principles of the currently used anticancer agents have been initially isolated from plants. Most of the herbal drugs are a mixture of a number of plant ingredients. Their cumulative effect increases the efficacy of the drug in curing the diseases. Muthu Marunthu is a herbal formulation comprising of eight various plant ingredients, and has been claimed to possess antitumor effect. Therefore, attention has been focused on studying the various plant ingredients in the drug as a whole for its antitumor effects. It was observed that the growth rate in rats was normal and there was no change in blood parameters such as glucose, urea, proteins, cholesterol and also in the activities of pathophysiological enzymes such as lactate dehydrogenase (LDH), glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), alkaline and acid phosphatase after Muthu Marunthu administration. The tumor weight was found to be reduced in methylcholanthrene induced fibrosarcoma rats after Muthu Marunthu treatment. Elevated levels of glycocomponents of glycoproteins such as hexose, hexosamine, sialic acid and fucose in plasma of fibrosarcoma rats decreased significantly after Muthu Marunthu treatment. The DNA and RNA levels of liver and kidney, which were increased in fibrosarcoma rats, returned to near normal levels after Muthu Marunthu treatment. The vitamins such as A, C and E in plasma were decreased in fibrosarcoma rats but increased significantly after Muthu Marunthu treatment. The altered levels of copper, zinc and selenium in plasma have also been corrected after Muthu Marunthu treatment. These observations clearly suggested the antitumor potency of Muthu Marunthu in experimentally induced fibrosarcoma in rats.
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PMID:Biochemical evaluation of antitumor effect of muthu marunthu (a herbal formulation) on experimental fibrosarcoma in rats. 1040 24

Oval cells are liver epithelial cells that proliferate during the early stages of hepatocarcinogenesis induced by a variety of chemicals. The oval cell lines OC/CDE 6 and OC/CDE 22 have been established in our laboratory at two time points (6 and 22 weeks) of the carcinogenic process and have been malignantly transformed by different procedures. During the transformation process, the glycolytic and glutaminolytic flux rates were consistently up-regulated and this process was accompanied by an overproportional increase in the activities of cytosolic hexokinase and 6-phosphogluconate dehydrogenase. In transformed oval cells, a strong correlation between the glycolytic flux rate and glutamine consumption as well as glutamate production was observed. Furthermore, the transport of glycolytic hydrogen, produced by the glyceraldehyde 3-phosphate dehydrogenase-catalyzed reaction, from the cytosol into the mitochondria by means of the malate-aspartate shuttle was enhanced, this being due to alterations in the activities of malate dehydrogenase and glutamate oxaloacetate transaminase. The up-regulation of the glycolytic hydrogen transport and the alterations in the glycolytic enzyme complex led to an enhanced pyruvate production at high glycolytic flux rates. Taken together, our data are further proof that a special metabolic feature (increased glycolysis and glutaminolysis) is characteristic for tumor cells and that the mechanisms by which this metabolic state is induced can be totally different.
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PMID:Alterations in the glycolytic and glutaminolytic pathways after malignant transformation of rat liver oval cells. 1045 61

High-dose interleukin-2 (IL-2) therapy has a response rate of approximately 20% in patients with metastatic melanoma and renal cell cancer. Animal models have shown that the anti-tumor effects of IL-2 are dose and schedule dependent, and one report has shown that patients with melanoma who responded to IL-2 therapy received more doses of IL-2 than did those who did not respond. The current study evaluated patients' tolerance to IL-2 over multiple courses of therapy and the factors that affected the number of doses delivered. Patients with metastatic melanoma or renal cell cancer who received at least two consecutive courses of high-dose intravenous IL-2 alone from October 1, 1985 through December 31, 1996 were evaluated. Patients served as their own controls in paired analyses. The number of doses tolerated from one course to the next and the reasons for stopping therapy were analyzed. One hundred fifty-nine patients received two or more courses of therapy during the study. The median number of doses of high-dose IL-2 decreased from course 1 (15 doses) to course 2 (12 doses) (p2 = 0.0001). Pretreatment factors were not found to significantly influence the decrease in the number of doses delivered. Only 2 of 33 separate toxic effects resulting in discontinuation of IL-2 dosing were found to be significantly different between courses. After adjusting for multiple tests of statistical significance, serum aspartate aminotransferase elevations were more likely to stop course 1 (p2 = 0.0033) and creatinine elevations were more likely to stop course 2 (p2 = 0.00007). The influence of renal toxicity was further assessed by comparing the median creatinine value at the time IL-2 dosing was discontinued. This difference was found to be significant when cycle 1 of course 1 (1.5 mg/dL) was compared with cycle 1 of course 2 (1.8 mg/dL; p2 = 0.0001). When pretreatment factors were analyzed, male sex (p2 = 0.006), a diagnosis of renal cell cancer (p2 = 0.008), previous nephrectomy (p2 = 0.001), and older age (p2 = 0.0055) were significantly associated with the development of renal toxicity that resulted in discontinuation of IL-2 therapy. Furthermore, the same four patient subsets had higher baseline creatinine values in individual univariate analyses. This study identified subsets of patients who tolerated less IL-2 with repeated courses. The decreasing tolerance to IL-2 was associated primarily with elevations in creatinine. Finding ways to ameliorate the renal toxicity seen during IL-2 therapy in this patient population may allow an increase in the number of IL-2 doses administered and potentially an increase in clinical response.
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PMID:Decreased tolerance to interleukin-2 with repeated courses of therapy in patients with metastatic melanoma or renal cell cancer. 1083 68

Because in experimental hepatocarcinogenesis apoptosis increases from normal to preneoplastic to carcinoma tissue, proapoptotic factors, such as activin-A, may represent useful markers for hepatocellular carcinoma (HCC). In this study, serum activin-A was measured in 99 cirrhotic patients, of whom 55 had HCC. Activin-A concentrations were higher in HCC patients (median, 2.33 ng/ml; range, 0.41-8.12) than in patients with nonmalignant cirrhosis (1.28 ng/ml; range, 0.35-6.25) (P < .05). All 12 patients with activin-A greater than 3 ng/ml and serum alpha-fetoprotein greater than 30 ng/ml had HCC, in comparison to 32 of 41 patients who had only one and to 11 of 46 patients who had both markers below these cutoffs (P < .0001). No correlation was found between activin-A and alpha-fetoprotein in the two groups, whereas in patients with HCC, activin-A was strictly correlated with serum aspartate aminotransferase (P < .001). Activin-A mRNA for inhibin betaA subunit was expressed both in tumor and nontumor liver tissues in a case of HCC superimposed on cirrhosis and was not expressed in a case of HCC without cirrhosis. In conclusion, cirrhotic patients with HCC have high serum activin-A, to the production of which both the cirrhotic liver and the liver tumor are likely to contribute.
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PMID:Evaluation of circulating activin-A as a serum marker of hepatocellular carcinoma. 1091 35

Recent studies have shown that expression levels of the multidrug resistance gene MDR1, which encodes the drug transporter P-glycoprotein, correlate with prognostic outcomes of certain tumor types. These findings suggest that expression of MDR1 may affect tumor behaviors. To address this issue further, we investigated the expression of mdr1a, a human MDR1 homolog, on the development of hepatocellular carcinoma in a transgenic mouse model carrying the liver-targeted expression of human hepatitis-B virus (HBV) surface antigen. The pathogenetic program was compared in HBV mice carrying either mdr1a(+/+) or mdr1a(-/-). We found that the expressions of proliferative activity markers, Ki67 nuclear antigen, and proliferating cell nuclear antigen were elevated in mdr1a(-/-) mice younger than 10 wk in comparison with those in the same age group of wild-type animals. Replication in the hepatic population as determined by bromodeoxyuridine incorporation tended to support observation that mdr1a(-/-) mice exhibited elevated labeling indices in this age group. Moreover, histologic staining and flow-cytometric analysis showed that the mdr1a(-/-) animals exhibited a higher cell population with polyploidy than did the mdr1a(+/+) counterparts of the same age. However, no significant differences in the expression of the liver-injury markers serum alanine transaminase and aspartate transaminase were observed. Although our results showed that absence of mdr1a expression is correlated with modest enhanced proliferative characteristics in the livers at stage before the development of hepatocellular carcinoma, the overall life spans between these two strains of mice were not significantly different. The implication of these findings to the role of P-glycoprotein in tumor development and cancer chemotherapy is discussed.
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PMID:Elevated expression of hepatic proliferative markers during early hepatocarcinogenesis in hepatitis-B virus transgenic mice lacking mdr1a-encoded P-glycoprotein. 1107 7

Ecteinascidin (ET) 743 is an anticancer agent derived from the Caribbean tunicate Ecteinascidia turbinata. Preclinical studies revealed activity of ET-743 against different tumor types. A Phase I clinical trial was designed with ET-743 to identify the maximum tolerated dose and dose-limiting toxicities (DLTs). Furthermore, the pharmacokinetics of ET-743 and relationships with pharmacodynamics were evaluated. Adult patients with solid, resistant tumors received ET-743 as a 24-h i.v. infusion every 21 days. Blood samples were obtained during the first treatment course and in several consecutive courses. Noncompartmental pharmacokinetic analysis was performed. Relationships between pharmacokinetics and hepatic and hematological toxicities were explored. Fifty-two patients were treated at nine dose levels (50-1800 microg/m2). The DLTs, neutropenia and thrombocytopenia, were experienced at 1800 microg/m2. Twenty-five patients were treated at the recommended Phase II dose of 1500 microg/m2. At this dose, the mean value +/- SD for total body clearance was 59 +/- 31 liters/h, and the mean t(1/2) was 89 +/- 41 h. Pharmacokinetics were linear over the dose range tested. Prior exposure to ET-743 did not alter the pharmacokinetics in subsequent courses. The percentage of decrease in WBC count and absolute neutrophil count was correlated to the area under the plasma concentration versus time curve (AUC). Hepatic toxicity, defined as rise in alanine aminotransferase and aspartate aminotransferase, increased with dose and AUC but was reversible and not dose limiting. In conclusion, ET-743 administered as a 24-h i.v. infusion at a dose of 1500 microg/m2 is clinically feasible; severe thrombocytopenia and neutropenia are the DLTs.
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PMID:Pharmacokinetics and pharmacodynamics of the novel marine-derived anticancer agent ecteinascidin 743 in a phase I dose-finding study. 1115 26

Prognosis and outcome of patients with pancreatic carcinoma is poor. The aim of the study was to investigate (1) which factors of medical history and clinical status as well as which laboratory parameters determine survival in pancreatic carcinoma and (2) whether specific data can be used as prognostic parameters or for early diagnosis of pancreatic carcinoma. In total, 287 patients with pancreatic carcinoma were enrolled in the study. In 193 subjects, only palliative treatment was possible. Survival was assessed using univariate survival probability curves by Kaplan-Meier. Comparison of patient groups with regard to survival was achieved using the log-rank test. Multivariate analysis was carried out using the Cox regression model. Overall, 22 factors, showing a significant impact on survival in pancreatic carcinoma were found, e.g., tumor-associated factors such as (1) tumor stage according to the UICC classification including TNM-based staging, grading, tumor site, and vascular infiltration; (2) preoperative habits and signs and symptoms (physical condition, pain, loss of appetite, ethanol consumption); (3) change of laboratory parameters (CA 19-9, bilirubin, prothrombin time, urea, C-reactive protein), and (4) type of intervention (surgical approach, R0/1/2 resection). Using multivariate analysis, seven factors (UICC tumor stage and site, surgical intervention including number of resected lymph nodes, chemotherapy, occurence of a carcinoma in relatives, preoperative physical condition, night sweat) were determined. In the 193 patients with palliative treatment, only ten factors (among them UICC tumor stage including the presence of metastases; data from the medical history such as physical condition, loss of appetite, and carcinoma in relatives, and laboratory parameters including prothrombin time, protein content, and aspartate aminotransferase levels) were found to be important. Chemotherapy had the strongest impact on survival which was confirmed by multivariate analysis, followed by tumor stage (UICC) and preoperative appetite. Besides tumor-associated determinants, data from the medical history, and pathological laboratory parameters, the prognosis in pancreatic carcinoma is considerably determined by the treatment such as interventional and/or using antineoplastic agents.
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PMID:Prognostic parameters determining survival in pancreatic carcinoma and, in particular, after palliative treatment. 1138 55


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