Genetic variation and haplotype structures of the glutathione S-transferase genes GSTA1 and GSTA2 in Japanese colorectal cancer patients.
ABSTRACT Glutathione S-transferases (GSTs) play a vital role in the phase II biotransformation of many chemicals, including anticancer drugs. In this study, to elucidate the haplotype structures of the two closely related alpha-class genes GSTA1 and GSTA2, we screened for genetic variation in 214 Japanese colorectal cancer patients who received oxaliplatin-based chemotherapy. By direct resequencing of the 5'-flanking region, all the exons, and their flanking introns for 107 patients, 29 and 27 variants were identified in GSTA1 and GSTA2, respectively. The known functional single nucleotide polymorphisms (SNPs) -567T>G, -69C>T, and -52G>A in GSTA1*B were found at allele frequencies of 0.140. Of the four major GSTA2 allelic variants reported previously (GSTA2*A, *B, *C, and *E), only GSTA2*B (frequency = 0.154), *C (0.706), and *E (0.140) were detected. Following linkage disequilibrium analysis, haplotypes of both genes were separately estimated. Then, rapid genotyping methods for 7 and 6 SNPs tagging common haplotypes of GSTA1 and GSTA2, respectively, were developed using the single-base extension assay, and an additional 107 patients were genotyped. Finally, haplotype combinations of both genes were classified into 3 major types: GSTA1*A-GSTA2*C, GSTA1*A-GSTA2*B, and GSTA1*B-GSTA2*E. These findings will be useful in pharmacogenomic studies on xenobiotics including anticancer drugs.
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ABSTRACT: Busulfan liver metabolism depends on glutathione, a crucial mediator of cellular and systemic stress. Here we investigated 40 polymorphisms at 27 loci involved in hepatic glutathione homeostasis, with the aim to test their impact on the clinical outcome of 185 busulfan-conditioned allogeneic transplants. GSTA2 S112T serine allele homozygosity is an independent prognostic factor for poorer survival (RR=2.388), for increased any time- and 100-day Transplant Related Mortality (RR=4.912 and RR=5.185, respectively). The genotype also predicts a wider busulfan area under the concentration-time curve (1214.36+570.06 vs 838.10+282.40 μMol*min) and higher post-transplant bilirubin serum levels (3.280+0.422 vs 1.874+0.197 mg/dL). In vitro, busulfan elicits pro-inflammatory activation (increased NF-KappaB activity and interleukin-8 expression) in human hepatoma cells. At the same time, the drug down-regulates a variety of genes involved in bilirubin liver clearance: constitutive androstane receptor, multidrug resistance-associated protein, solute carrier organic anion transporters, and even GSTA2. Worthy of note, is the fact that GSTA2 also acts as an intra-hepatic bilirubin binding protein. These data underline the prognostic value of GSTA2 genetic variability in busulfan-conditioned allotransplants and suggest a patho-physiological model in which busulfan-induced inflammation leads to the impairment of post-transplant bilirubin metabolism.Haematologica 09/2013; · 5.94 Impact Factor