Effect of polymorphism in the human glutathione S-transferase A1 promoter on hepatic GSTA1 and GSTA2 expression

Abstract

The patterns of expression of glutathione S-transferases A1 and A2 in human liver (hGSTA1 and hGSTA2, respectively) are highly variable, notably in the ratio of hGSTA1/hGSTA2. We investigated if this variation had a genetic basis by sequencing the proximal promoters (-721 to -1 nucleotides) of hGSTA1 and hGSTA2, using 55 samples of human liver that exemplified the variability of hGSTA1 and hGSTA2 expression. Variants were found in the hGSTA1 gene: -631T or G, -567T, -69C, -52G, designated as hGSTA1*A; and -631G, -567G, -69T, -52A, designated as hGSTA1*B. Genotyping for the substitution -69C > T by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP), showed that the polymorphism was widespread in Caucasians, African-Americans and Hispanics, and that it appeared to conform to allelic variation. Constructs consisting of the proximal promoters of hGSTA1*A, hGSTA1*B or hGSTA2, with luciferase as a reporter gene, showed differential expression when transfected into HepG2 cells: hGSTA1*A approximately hGSTA2 > hGSTA1*B. Similarly, mean levels of hGSTA1 protein expression in liver cytosols decreased significantly according to genotype: hGSTA1*A > hGSTA1-heterozygous > hGSTA1*B. Conversely, mean hGSTA2 expression increased according to the same order of hGSTA1 genotype. Consequently, the ratio of GSTA1/GSTA2 was highly hGSTA1 allele-specific. Because the polymorphism in hGSTA1 correlates with hGSTA1 and hGSTA2 expression in liver, and hGSTA1-1 and hGSTA2-2 exhibit differential catalysis of the detoxification of carcinogen metabolites and chemotherapeutics, the polymorphism is expected to be of significance for individual risk of cancer or individual response to chemotherapeutic agents.

Glutathione S-transferase gene variations influence BU pharmacokinetics and outcome of hematopoietic SCT in pediatric patients

“…Gene-dosage effect was also noted. Our observation is in accordance with the functional studies suggesting higher GSTA activity in GSTA1*A carriers 10,22,24 and is also supported by several previous reports. 17,[26][27][28][29][30] Decreased CL following oral BU was seen in adults and children with GSTA*B haplotype; 17,29,31 a significant decrease in CL following i.v.…”

“…17,[26][27][28][29][30] Decreased CL following oral BU was seen in adults and children with GSTA*B haplotype; 17,29,31 a significant decrease in CL following i.v. BU was observed in pediatric GSTA1*B patients; 21,22 and accordingly increased BU CL correlated with GSTA1*A haplotype. 17,39 However, a few studies conducted in adults and children 15,31,32 failed to show such an association, which might be due to low sample size, 15 31 or different methods of estimating BU PK might also have contributed to the conflicting observations.…”

“…2,[12][13][14] Body weight and body surface area have been also shown to contribute to PK variability. [15][16][17][18][19] Nevertheless, a large proportion of BU variability remains unexplained 20 and could be due to GST polymorphisms influencing GST activity [21][22][23][24][25] (Table 1). Although some studies have shown that GSTA1 genotypes influence the PK of oral and i.v.…”

Glutathione S-transferase A1 polymorphism and the risk of recurrent spontaneous abortion in Chinese Han population

“…Three different genotypes (CC, CT and TT) of GSTA1 −69C/T polymorphism reported previously were observed after digesting the amplified DNA fragment of 899 bp with the restriction enzyme EarI [17]. The enzymatic restriction products of the rs3957357 were of the expected size.…”

Association of cyclophosphamide pharmacokinetics to polymorphic cytochrome P450 2C19

“…Discrimination between the GSTA1 alleles *A and *B was achieved by using Ear I for PCR/RFLP analysis. 37 Analysis of CP Plasma Concentrations Plasma levels of CP (Sigma-Aldrich, Steinheim, Germany) were measured by high-performance liquid chromatography (HPLC). An aliquot of 100 ml plasma was spiked with 6 mg of the internal standard ifosfamide (Baxter Oncology GmbH, Frankfurt am Main, Germany) and extracted with 1 ml Bakerbond spet Octadecyl (C18) solid-phase extraction columns (Mallinckrodt Baker, Deventer, Netherlands).…”