Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.1.1.67 (thiopurine methyltransferase)
 551 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The nature of mendelian inheritance assumes that all tissues in which a phenotype of interest is expressed have a uniform diploid karyotype, which is often not the case in cancer cells. Owing to nonrandom gains of chromosomes, trisomies are present in many cases of leukemia and other malignances. We used polymorphisms in the genes encoding thiopurine S-methyltransferase (TPMT), gamma-glutamyl hydrolase (GGH) and the reduced folate carrier (SLC19A1) to assess the nature of chromosomal acquisition and its influence on genotype-phenotype concordance in cancer cells. TPMT and GGH activities in somatic cells were concordant with germline genotypes, whereas activities in leukemia cells were determined by chromosomal number and whether the acquired chromosomes contained a wild-type or variant allele. Leukemia cells that had acquired an additional chromosome containing a wild-type TPMT or GGH allele had significantly lower accumulation of thioguanine nucleotides or methotrexate polyglutamates, respectively. Among these genes, there was a comparable number of acquired chromosomes with wild-type and variant alleles. Therefore, chromosomal gain can alter the concordance of germline genotype and cancer cell phenotypes, indicating that allele-specific quantitative genotyping may be required to define cancer pharmacogenomics unequivocally.
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PMID:Karyotypic abnormalities create discordance of germline genotype and cancer cell phenotypes. 1604 4

We investigated preliminarily whether methylenetetrahydrofolate reductase (MTHFR) 677C/T or reduced folate carrier 1 (RFC1) 80G/A polymorphisms were associated with toxicities during maintenance chemotherapy with mercaptopurine (6MP) and methotrexate (MTX) in children with acute lymphoblastic leukemia or lymphoblastic lymphoma. The clinical records of 20 children (2 to 15-y old) who had received maintenance chemotherapy were reviewed retrospectively and their genomic DNA was genotyped to identify polymorphisms at MTHFR 677C/T, RFC1 80G/A, and thiopurine methyltransferase 719A/G. Maintenance chemotherapy with 6MP and MTX was repeated on a weekly basis, and any week during which 6MP and/or MTX dosing was withheld was counted as an interrupted episode. Associations between the risk of interruptions and polymorphisms were studied using a generalized estimating equation analysis. Patients with an increasing number of T alleles at MTHFR 677C/T experienced interruptions in both 6MP (P<0.01) and MTX (P=0.03) more frequently. Patients with an increasing number of A alleles at RFC1 80G/A experienced interruptions in 6MP (P=0.04) more frequently. This preliminary study does not prove but suggests that MTHFR 677C/T and RFC1 80G/A polymorphisms may serve as predictors of toxicity during maintenance chemotherapy.
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PMID:Influence of MTHFR and RFC1 polymorphisms on toxicities during maintenance chemotherapy for childhood acute lymphoblastic leukemia or lymphoma. 1845 67

We explored the impact of mutations in the NOTCH1, FBW7 and PTEN genes on prognosis and downstream signaling in a well-defined cohort of 47 patients with pediatric T-cell acute lymphoblastic leukemia (T-ALL). In T-ALL lymphoblasts, we identified high-frequency mutations in NOTCH1 (n=16), FBW7 (n=5) and PTEN (n=26). NOTCH1 mutations resulted in 1.3- to 3.3-fold increased transactivation of an HES1 reporter construct over wild-type NOTCH1; mutant FBW7 resulted in further augmentation of reporter gene activity. NOTCH1 and FBW7 mutations were accompanied by increased median transcripts for NOTCH1 target genes (HES1, DELTEX1 and cMYC). However, none of these mutations were associated with treatment outcome. Elevated HES1, DELTEX1 and cMYC transcripts were associated with significant increases in transcript levels of several chemotherapy relevant genes, including MDR1, ABCC5, reduced folate carrier, asparagine synthetase, thiopurine methyltransferase, BCL2 and dihydrofolate reductase. PTEN transcripts positively correlated with HES1 and cMYC transcript levels. Our results suggest that (1) multiple factors should be considered with attempting to identify molecular-based prognostic factors for pediatric T-ALL, and (2) depending on the NOTCH1 signaling status, modifications in the types or dosing of standard chemotherapy drugs for T-ALL, or combinations of agents capable of targeting NOTCH1, AKT and/or mTOR with standard chemotherapy agents may be warranted.
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PMID:The impact of NOTCH1, FBW7 and PTEN mutations on prognosis and downstream signaling in pediatric T-cell acute lymphoblastic leukemia: a report from the Children's Oncology Group. 1934 1