Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.3.1.21 (CPT)
4,580 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In MAG-camptothecin (MAG-CPT), the topoisomerase inhibitor camptothecin is linked to a water-soluble polymer. Preclinical experiments showed enhanced antitumour efficacy and limited toxicity compared to camptothecin alone. Prior phase I trials guided the regimen used in this study. The objectives were to determine the maximum tolerated dose, dose-limiting toxicities, safety profile, and pharmacokinetics of weekly MAG-CPT. Patients with solid tumours received MAG-CPT intravenously administered weekly for 3 weeks in 4-week cycles. At the starting dose level (80 mg x m(-2) week(-1)), no dose-limiting toxicities occurred during the first cycle (n=3). Subsequently, three patients were enrolled at the second dose level (120 mg x m(-2) week(-1)). Two of three patients at the 80 mg x m(-2) week(-1) cohort developed haemorrhagic cystitis (grade 1/3 dysuria and grade 2/3 haematuria) during the second and third cycles. Next, the 80 mg x m(-2) week(-1) cohort was enlarged to a total of six patients. One other patient at this dose level experienced grade 1 haematuria. At 120 mg x m(-2) week(-1), grade 1 bladder toxicity occurred in two of three patients. Dose escalation was stopped at 120 mg x m(-2) week(-1). Cumulative bladder toxicity was dose-limiting toxicity at 80 mg x m(-2) week(-1). Pharmacokinetics revealed highly variable urinary camptothecin excretion, associated with bladder toxicity. Due to cumulative bladder toxicity, weekly MAG-CPT is not a suitable regimen for treatment of patients with solid tumours.
Br J Cancer 2004 Jun 14
PMID:A phase I study with MAG-camptothecin intravenously administered weekly for 3 weeks in a 4-week cycle in adult patients with solid tumours. 1515 Jun 11

Polymeric cytotoxic conjugates are being developed with the aim of preferential delivery of the anticancer agent to tumour. MAG-CPT comprises the topoisomerase I inhibitor camptothecin linked to a water-soluble polymeric backbone methacryloylglycynamide (average molecular weight 18 kDa, 10% CPT by weight). It was administered as a 30-min infusion once every 4 weeks to patients with advanced solid malignancies. The objectives of our study were to determine the maximum tolerated dose, dose-limiting toxicities, and the plasma and urine pharmacokinetics of MAG-CPT, and to document responses to this treatment. The starting dose was 30 mg m(-2) (dose expressed as mg equivalent camptothecin). In total, 23 patients received 47 courses at six dose levels, with a maximum dose of 240 mg m(-2). Dose-limiting toxicities were myelosuppression, neutropaenic sepsis, and diarrhoea. One patient died after cycle 1 MAG-CPT at the maximum dose. The maximum tolerated dose and dose recommended for further clinical study was 200 mg m(-2). The half-lives of both MAG-CPT and released CPT were prolonged (>6 days) and measurable levels of MAG-CPT were retrieved from plasma and urine 4 weeks after treatment. However, subsequent pharmacodynamic studies of this agent have led to its withdrawal from clinical development.
Br J Cancer 2004 Jul 05
PMID:Phase I and pharmacokinetic (PK) study of MAG-CPT (PNU 166148): a polymeric derivative of camptothecin (CPT). 1518 95

In an effort to improve the water solubility of camptothecin, 16 water soluble 10-substituted quaternary ammonium salt derivatives of camptothecin were prepared. Their antitumor activity was evaluated on cancer cells in vitro. All of these salts possess lower cytotoxicities than CPT in comparison. The camptothecin salts 16, 20 showed similar cytotoxic activity to topotecan. Especially the salts 21 showed similar cytotoxic activity to CPT in vitro.
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PMID:Synthesis and cytotoxicity of water soluble quaternary salt derivatives of camptothecin. 1522 19

To compare irinotecan (CPT-11)+gemcitabine vs CPT-11 alone as second-line treatment for patients with advanced non-small cell lung cancer (NSCLC) progressing after docetaxel-cisplatinum-based therapy. A total of 147 evaluable, pretreated patients, with NSCLC, received either gemcitabine (1000 mg m(-2), days 1 and 8)+CPT-11 (300 mg m(-2), day 8) (Group A, n=76) or CPT-11 (300 mg m(-2), day 1) (Group B, n=71), every 3 weeks. All patients were evaluable for response and toxicity. The objective response rate was 18.4% (95% CI: 9.71-27.14%) and 4.2% (95% CI: 0-8.90%) (P=0.009) for groups A and B, respectively. No significant differences between the two groups in terms of the median duration of response, time to tumour progression, overall survival and 1-year survival were observed. The CPT-11/gemcitabine regimen significantly improved the patients' quality of life ('general mood today' (P=0.014), 'coughing' (P=0.003) and 'intensity of symptoms' (P=0.034)) compared with CPT-11. More cycles had to be delayed (P=0.001) and required prophylactic growth factor support (P=0.001) in Group A than B. Three (3.9%) patients in Group A and eight (11.3%) in Group B developed febrile neutropenia (P=0.09); one patient died of sepsis in each group. Three additional (Group A, n=1; Group B, n=2) treatment-related deaths were observed. Grade 3-4 haematologic toxicity was comparable in the two groups except anaemia (P=0.03 in favour of CPT-11). Other nonhaematologic toxicities were mild and similar in the two groups. CPT-11+gemcitabine resulted in a higher response rate and better control of disease-related symptoms than CPT-11 alone, but without any improvement in the overall survival.
Br J Cancer 2004 Aug 02
PMID:Irinotecan plus gemcitabine vs irinotecan for the second-line treatment of patients with advanced non-small-cell lung cancer pretreated with docetaxel and cisplatin: a multicentre, randomised, phase II study. 1523 86

Hepatic mitochondrial outer membrane carnitine palmitoyltransferase I (CPT I) and mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase (HMG-CoA synthase) enzymes play a key role in regulation of fatty acid oxidation and in ketogenic pathways, respectively. Their expression are regulated by fatty acids mainly by the peroxisome proliferator-activated receptor alpha (PPARalpha). To investigate possible mechanisms through which cancer alters the lipid metabolism, we analyzed by Northern blot, the mRNA relative abundance of these proteins in liver from healthy and DMBA-induced mammary tumor-bearing rats fed a low or high corn oil diet. Serum levels of lipids, body weight and mass were also determined. Whereas mRNA steady-state levels of CPT I and mit HMG-CoA synthase were unaffected by the presence of the extra-hepatic tumor, the cancer state seemed to modify the regulation of the expression of these genes by high fat diet. We hypothesize that putative changes in PPARalpha mRNA levels could have contributed to such alterations. These results, together with changes in serum lipid profiles, body weight and mass, indicate fat mobilization and non-enhanced oxidation rates despite a high-fat feeding. This effect of the cancer state could be related to tumor aggressiveness and suggest a preferential redirection of long-chain fatty acids into energetic and specific pathways of the cancer cells.
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PMID:Influence of DMBA-induced mammary cancer on the liver CPT I, mit HMG-CoA synthase and PPARalpha mRNA expression in rats fed a low or high corn oil diet. 1525 79

Twenty-three quassinoids (1-23), which were isolated previously from Simaroubaceous plants, were evaluated for cytotoxicity against three multidrug-resistant cancer cell lines, KB-VIN, KB-7d, and KB-CPT. Nine compounds (2-7 and 9-11) showed significant cytotoxicity in all three cell lines. Compounds 1, 12-14, 17, and 20 demonstrated significant activity against the KB-7d and KB-CPT cell lines, and compounds 18, 19, and 23 revealed notable activity only against KB-7d cells. Structure-activity relationships were drawn based on these data. In addition, six quassinoid derivatives (24-29) and four canthin alkaloids (30-33), which were isolated from Brucea antidysenterica, were examined for their inhibitory effects on 12-O-tetradecanoylphorbol-13-acetate (TPA) induced Epstein-Barr virus early antigen (EBV-EA) activation as cancer chemopreventive agents. All of these compounds demonstrated significant inhibitory effects against EBV-EA activation.
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PMID:Multidrug-resistant cancer cell susceptibility to cytotoxic quassinoids, and cancer chemopreventive effects of quassinoids and canthin alkaloids. 1533 75

Camptothecins selectively target topoisomerase I (Top1) by trapping the catalytic intermediate of the Top1-DNA reaction, the cleavage complex. Hence, camptothecins represent a paradigm for targeting macromolecular interactions. Instead of preventing the binding of the two macromolecules they target (Top1 and DNA), camptothecins slow down the dissociation of these macromolecules. The activity of camptothecins underlines the usefulness of screening for drugs that inhibit the dissociation of macromolecules. Camptothecins and non-CPT Top1 inhibitors are being developed to improve the pharmacodynamics, pharmacokinetics and clinical pharmacology of camptothecins, and it is likely that drugs with improved anticancer activity will be discovered. Although Top1 is the only primary target of camptothecins, the mechanisms of camptothecins' anticancer activity rest beyond the formation of cleavage complexes. Indeed, Top1 cleavage complexes lead to replication- (and transcription-) mediated DNA damage. It is likely that DNA damage can be repaired more efficiently in normal than in cancer cells that are intrinsically deficient for DNA repair and cell cycle checkpoints. Evaluating such deficiencies in clinical samples is becoming possible. If specific deficiencies are associated with clinical responses, their detection should guide therapeutic decisions. Furthermore, targeting DNA repair (Tdp1) and checkpoints (ATM, Chk1 and Chk2) might increase the selectivity of Top1 inhibitors for tumors, thereby increasing the antitumor activity while reducing the side effects of Top1 inhibitors.
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PMID:Camptothecins and topoisomerase I: a foot in the door. Targeting the genome beyond topoisomerase I with camptothecins and novel anticancer drugs: importance of DNA replication, repair and cell cycle checkpoints. 1537 98

A 54-year-old man underwent abdominoperineal resection for rectal cancer. Adjuvant chemotherapy was not performed because of stage I cancer. Nine months after the operation, solitary liver metastasis, and elevated CEA and CA19-9, were found during the postoperative work-up. A combination chemotherapy of CPT-11 and UFT-E was performed before scheduled liver resection. 150 mg/m2 of CPT-11 was administered on days 1 and 15. 375 mg/m2/day of UFT-E was divided in half and administered on days 3-7, 10-14, 17-21, and 24-28 as one course of treatment. This regimen was repeated every 5 weeks. The patient had a grade 2 diarrhea and nentropenia during the treatment. Bowel obstruction was also observed after 5 courses of treatment, which required hospitalization. In addition, the liver metastasis had disappeared. There was no evidence of recurrence after 8 months of chemotherapy. It was suggested that CPT-11+UFT-E combination chemotherapy was effective for advanced colorectal cancer.
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PMID:[Case report--Complete response of liver metastasis of rectal cancer after combination chemotherapy of CPT-11 + UFT-E]. 1555 88

Activation of the oncogenic kinase Akt stimulates glucose uptake and metabolism in cancer cells and renders these cells susceptible to death in response to glucose withdrawal. Here we show that 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) reverses the sensitivity of Akt-expressing glioblastoma cells to glucose deprivation. AICAR's protection depends on the activation of AMPK, as expression of a dominant-negative form of AMPK abolished this effect. AMPK is a cellular energy sensor whose activation can both block anabolic pathways such as protein synthesis and activate catabolic reactions such as fatty acid oxidation to maintain cellular bioenergetics. While rapamycin treatment mimicked the effect of AICAR on inhibiting markers of cap-dependent translation, it failed to protect Akt-expressing cells from death upon glucose withdrawal. Compared to control cells, Akt-expressing cells were impaired in the ability to induce fatty acid oxidation in response to glucose deprivation unless stimulated with AICAR. Stimulation of fatty acid oxidation was sufficient to maintain cell survival as activation of fatty acid oxidation with bezafibrate also protected Akt-expressing cells from glucose withdrawal-induced death. Conversely, treatment with a CPT-1 inhibitor to block fatty acid import into mitochondria prevented AICAR from stimulating fatty acid oxidation and promoting cell survival in the absence of glucose. Finally, cell survival did not require reversal of Akt's effects on either protein translation or lipid synthesis as the addition of the cell penetrant oxidizable substrate methyl-pyruvate was sufficient to maintain survival of Akt-expressing cells deprived of glucose. Together, these data suggest that activation of Akt blocks the ability of cancer cells to metabolize nonglycolytic bioenergetic substrates, leading to glucose addiction.
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PMID:The glucose dependence of Akt-transformed cells can be reversed by pharmacologic activation of fatty acid beta-oxidation. 1580 54

The CD94/NKG2A heterodimer is a natural killer receptor (NKR), which inhibits cell-mediated cytotoxicity upon interaction with MHC class I gene products. It is expressed by NK cells and by a small fraction of activated T cells, predominantly of CD8+ phenotype. Abnormal upregulation of the CD94/NKG2A inhibitory NKR on cytotoxic T cells (CTLs) could be responsible for a failure of immunosurveillance in cancer or HIV infection. In an attempt to identify the mechanisms leading to inhibitory NKR upregulation on T cells, we analyzed the expression of the CD94/NKG2A heterodimer on human CTLs activated with anti-CD3 mAb in the presence of PGE2 or with 8-CPT-cAMP, an analogue of cyclic AMP. As previously described, anti-CD3 mAb-mediated activation induced the expression of CD94/NKG2A on a small fraction of CD8+ T cells. Interestingly, when low concentrations of PGE2 or 8-CPT-cAMP were present during the culture, the proportion of CD8+ T cells expressing CD94/NKG2A was two- to five-fold higher. This upregulation was partially prevented by PKA inhibitors, such as KT5720 and Rp-8-Br-cAMP (type I selective). We also report that cAMP induces upregulation of NKG2A at the mRNA level. We further demonstrated that cross-linking of CD94 on CD8+ T cells expressing the CD94/NKG2A heterodimer inhibits their cytotoxic activity in a bispecific antibody redirected lysis assay. Our findings clearly demonstrate that the PGE2/cAMP/PKA type I axis is involved in the expression of CD94/NKG2A receptor on human CD8+ T lymphocytes.
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PMID:Prostaglandin E2 induces the expression of functional inhibitory CD94/NKG2A receptors in human CD8+ T lymphocytes by a cAMP-dependent protein kinase A type I pathway. 1597 47


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