• Asian Pacific Journal of Cancer Prevention
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• v.15 no.4
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• pp.1719-1723
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• 2014

Background: The current study was aimed to elucidate the association of thymidylate synthase (TYMS) 5'-UTR 28bp tandem repeat and cytosolic serine hydroxymethyltransferase (cSHMT) C1420T polymorphisms with acute leukemia in South Indian subjects. A total of 812 subjects [523 healthy controls, 148 acute lymphoblastic leukemia (ALL) cases and 141 acute myeloid leukemia (AML) cases] were screened for TYMS 5'-UTR 28bp tandem repeat and cSHMT C1420T using PCR-AFLP and PCR-with confronting two-pair primers (CTPP) approaches. TYMS 5'-UTR 2R allele frequencies of controls, ALL and AML cases were 35.3%, 28.0% and 30.1% respectively. This polymorphism conferred protection against ALL (OR: 0.71, 95%CI: 0.53-0.96) while showing no statistically significant association with AML (OR: 0.79, 95%CI: 0.58, 1.07). The cSHMT variant allele (T-) frequencies of ALL and AML cases (6.42% and 5.68% respectively) were significantly lower compared to controls (58.3%). This polymorphism conferred protection against ALL (OR: 0.049, 95%CI: 0.029-0.081) and AML (OR: 0.043, 95%CI: 0.025-0.074). 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. No such genotype-dependent differences were observed in AML cases. ALL cases carrying the cSHMT C1420T polymorphism showed higher disease free survival compared to those with the wild genotype. To conclude, the TYMS 5'-UTR 28bp tandem repeat reduces risk for ALL while cSHMT C1420T reduces risk for both ALL and AML. Both also influence disease progression in ALL.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.5
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• pp.2257-2262
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• 2014

A series of studies have explored the role of cytosolic serine hydroxymethyltransferase (SHMT1) C1420T polymorphism in cancer risk, but their results were conflicting rather than conclusive. To derive a more precise estimation of the association between C1420T and cancer risk, the present meta-analysis of 28 available studies with 15,121 cases and 18,023 controls was conducted. The results revealed that there was no significant association between the polymorphism and cancer risk overall. In stratified analysis by cancer type (breast cancer, gastrointestinal cancer, leukemia, lymphoma, and others), the results showed that 1420T allele was associated with decreased risk in leukemia (CT vs. CC: OR= 0.825, 95% CI =0.704-0.966; and CT+TT vs. CC: OR= 0.838, 95% CI = 0.722-0.973), but the same results were not present for other cancer types. When subgroup analysis was performed by source of control (population-based [PB] and hospital-based [HB]), a borderline inverse association was observed for the HB subgroup (CT vs. CC: OR= 0.917, 95% CI = 0.857-0.982) but not for the PB subgroup. Stratifying by geographic area (America, Asia and Europe), significant inverse association was only found in Asia subgroup (CT vs. CC: OR= 0.674, 95% CI = 0.522-0.870). In summary, the findings suggest that SHMT1 C1420T polymorphism is not associated with overall cancer development, but might decrease cancer susceptibility of Asians as well as reduce leukemia risk. Large well-designed epidemiological studies will be necessary to validate the risk identified in the current meta-analysis.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.11
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• pp.5333-5338
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• 2012

Vitamin B6 functions as a coenzyme in >140 enzymatic reactions involved in the metabolism of amino acids, carbohydrates, neurotransmitters, and lipids. It comprises a group of three related 3-hydroxy-2-methyl-pyrimidine derivatives: pyridoxine (PN), pyridoxal (PL), pyridoxamine (PM) and their phosphorylated derivatives [pyridoxal 5'-phosphate (PLP) and pyridoxamine 5'-phosphate (PMP)], In the folate metabolism pathway, PLP is a cofactor for the mitochondrial and cytoplasmic isozymes of serine hydroxymethyltransferase (SHMT2 and SHMT1), the P-protein of the glycine cleavage system, cystathionine ${\beta}$-synthase (CBS) and ${\gamma}$-cystathionase, and betaine hydroxymethyltransferase (BHMT), all of which contribute to homocysteine metabolism either through folate-mediated one-carbon metabolism or the transsulfuration pathway. Folate cofactors carry and chemically activate single carbons for the synthesis of purines, thymidylate and methionine. So the evidence indicates that vitamin B6 plays an important role in maintenance of the genome, epigenetic stability and homocysteine metabolism. This article focuses on studies of strand breaks, micronuclei, or chromosomal aberrations regarding protective effects of vitamin B6, and probes whether it is folate-mediated one-carbon metabolism or the transsulfuration pathway for vitamin B6 which plays critical roles in prevention of cancer and cardiovascular disease.

• Toxicological Research
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• v.23 no.1
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• pp.55-63
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• 2007

Diethylnitrosamine (DEN) is a nitrosamine compound that can induce a variety of liver lesions including hepatic carcinoma, forming DNA-carcinogen adducts. In the present study, microarray analyses were performed with Affymetrix Murine Genome 430A Array in order to identify the gene-expression profiles for DEN and to provide valuable information for the evaluation of potential hepatotoxicity. C57BL/6NCrj mice were orally administered once with DEN at doses of 0, 3, 7 and 20 mg/kg. Liver from each animal was removed 2, 4, 8 and 24 hrs after the administration. The histopathological analysis and serum biochemical analysis showed no significant difference in DEN-treated groups compared to control group. Conversely, the principal component analysis (PCA) profiles demonstrated that a specific normal gene expression profile in control groups differed clearly from the expression profiles of DEN-treated groups. Within groups, a little variance was found between individuals. Student's t-test on the results obtained from triplicate hybridizations was performed to identify those genes with statistically significant changes in the expression. Statistical analysis revealed that 11 genes were significantly downregulated and 28 genes were upregulated in all three animals after 2 h treatment at 20 mg/kg. The upregulated group included genes encoding Gdf15, JunD1, and Mdm2, while the genes including Sox6, Shmt2, and SIc6a6 were largely down regulated. Hierarchical clustering of gene expression also allowed the identification of functionally related clusters that encode proteins related to metabolism, and MAPK signaling pathway. Taken together, this study suggests that match with a toxicant signature can assign a putative mechanism of action to the test compound if is established a database containing response patterns to various toxic compounds.