To analyze influence of variants in TYMS, MTHFR, SLC19A1 and DHFR genes on 6-mercaptopurine (MP) induced toxicity during maintenance phase of treatment for childhood acute lymphocytic leukemia (ALL).
This pilot study assessed whether expression of MRP1, MRP4, MRP5 and BCRP (real-time PCR) in primary childhood ALL blasts (n = 23) correlated with ex vivo resistance to MTX (assayed by in situ thymidylate synthase inhibition assay (TSIA)), ex vivo accumulation of (radioactive) MTX polyglutamates, and patient survival.
We analyzed the presence of a 28-base pair tandem repeat (rs34743033; 2R3R), a single nucleotide polymorphism present within the 28-base pair repeat on the 3R allele (rs2853542; 3RG>C) and a 6-base pair deletion (rs15126436; TTAAAG) within the TYMS gene in germline DNA of 117 pediatric patients with ALL.
VDR fok1 and TYMS polymorphic variants showed no association neither with gender; <i>P</i>-values 0.3808 and 0.1503, respectively, nor with ALL subtypes; <i>P</i>-values 0.9396 and 0.6596, respectively.
Accumulating studies have explored the effect of thymidylate synthase enhancer region (TSER) variation on risk of pediatric acute lymphoblastic leukemia (ALL) with controversial results.
The aims of this study were to (a) to determine the prevalence of seven common genetic polymorphisms including those that affect the folate and/or thiopurine metabolic pathways, i.e. cyclin D1 (CCND1-G870A), γ-glutamyl hydrolase (GGH-C452T), methylenetetrahydrofolate reductase (MTHFR-C677T and MTHFR-A1298C), thymidylate synthase promoter (TYMS-TSER), thiopurine methyltransferase (TPMT*3A and TPMT*3C) and inosine triphosphate pyrophosphatase (ITPA-C94A), in Caucasian (n = 94, age < 20) and Vietnamese (n = 141, age < 16 years) childhood ALL and (b) to assess the impact of a multilocus genetic risk score (MGRS) on relapse-free survival (RFS) using a Cox proportional-hazards regression model.
Among the investigated polymorphisms and mutations, NBN Glu185Gln significantly decreased susceptibility to B-cell ALL (p=0.037), while TYMS 3R allele decreased susceptibility to T-cell ALL (p=0.011).
The TYMS 5'-UTR 2R2R genotype was associated with a lower total leukocyte count, smaller percentage of blasts, and more adequate platelet count compared to 2R3R and 3R3R genotypes in ALL cases.
In conclusion, the TYMS TSER polymorphism may contribute to a susceptibility to risk of ALL in children and non-Hodgkin lymphoma in Caucasians, but protection from ALL risk in adults.
Children with ALL (n = 96) were screened for GCPII C1561T, RFC1 G80A, cSHMT C1420T, TYMS 5´-UTR 2R3R, TYMS 3´-UTR ins6/del6, MTHFR C677T, MTR A2756G polymorphisms using PCR-RFLP and PCR-amplified fragment length polymorphism techniques.
Thymidylate synthase and methionine synthase polymorphisms are not associated with susceptibility to childhood acute lymphoblastic leukemia in Kurdish population from Western Iran.
Therefore, HDACI-induced FPGS expression increases the accumulation of MTX-PG(3-7) and cytotoxicity in ALL cell lines, which is potentiated by DHFR and TS downregulation.
The analysis combining haplotype *1 with thymidylate synthase (TS) and cyclin D1 (CCND1) genotypes previously shown to affect ALL outcome showed that the number of event-predisposing genotypes was associated with increasingly lower EFS (P<.001).
We conducted a case-control study analyzing the prevalence of the polymorphisms CYP1A1*2A, CYP2E1*5B, CYP3A4*1B, del{GSTT1}, del{GSTM1}, NQO1*2, MTHFR C6777, and TYMS 2R/3R in 443 patients with AL [302 with acute myeloblastic leukemia (AML) and 141 with acute lymphoblastic leukemia (ALL)] and 454 control volunteers, using polymerase chain reaction (PCR)-based methods.
We analysed common genetic polymorphisms of 5,10-methylenetetrahydrofolate reductase (MTHFR), thymidylate synthase (TS), methionine synthase (MS) and methionine synthase reductase (MTRR) in 68 children with ALL and 258 healthy controls to investigate their influence on the risk for ALL.
In ALL, polymorphisms in the genes of folate metabolism are associated with poor prognosis, and the 3R3R TYMS polymorphism in particular is associated with methotrexate resistance.
Ex vivo MTX sensitivity of lymphoblasts obtained from pediatric patients with acute lymphoblastic leukemia (ALL; n = 157) was determined by the in situ thymidylate synthase inhibition assay after either continuous (21 hours; TSI(50, cont)) or short-term (3 hours; TSI(50, short)) MTX exposure.
In this report we analyzed the mRNA expression of the resistance-related enzymes DNA topoisomerase II (Topo II), thymidylate synthase (TS), glutathione S-transferase-pi (GST-pi) and glutathione peroxidase (GP) in childhood acute lymphoblastic leukemia (ALL) and their correlation to the proliferative activity, determined by Ki-67.