Genetic Monitoring of Human Polymorphic Cancer Susceptibility Genes by Polymerase Chain Reaction: Application to Glutathione Transferase m

Abstract

Several genes involved in the metabolism of carcinogens have been found to be polymorphic in human populations and are associated with increased risk of cancer at some sites. This study focuses on the polymorphic enzyme glutathione transferase mu (GT mu). Smokers with low lymphocyte GT mu activity are at an approximately 2-fold higher risk for lung cancer and an approximately 3-fold higher risk for stomach and colon adenocarcinomas. Recent cloning and sequencing of the GST1 gene has allowed the development of convenient genotyping methods based on restriction fragment length polymorphisms (RFLP) or the polymerase chain reaction (PCR). The GST1 polymorphism has been shown to be a deletion of the gene locus. To detect the presence or absence of the gene we amplified exons 4-5 and/or exons 6-7 of the GST1 gene by PCR. PCR amplification produced bands of 215-bp or 273-bp from individuals with one or two copies of the GST1 allele and no band if the individual was homozygously deleted (0/0). In the exon 6-7 PCR, we co-amplified a 268-bp portion of the beta-globin gene as an internal reference standard for quantitative analysis of product yield. This allowed homozygote individuals (+/+) to be distinguished from heterozygotes (+/0). We have compared the GST1 genotype to lymphocyte GT mu activity measured on trans-stilbene oxide (TSO) in the lymphocytes of 45 individuals. Low GT mu activity (< 67 pmole/min/10(7) cells) was strongly associated (24/24) with the GST1 0/0 genotype. With the exception of one individual, activities greater than 67 pmole/min/10(7) were associated with the presence of the GST1 allele (20/21). Individuals with the highest GT-TSO activity were found to be homozygous for GST1. (+/+), while heterozygotes (+/0) generally had lower activity, suggesting a gene dosage effect in lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of individual susceptibility in cancer burden related to environmental exposure.

“…About 50% of the Caucasian population inherits two deficient alleles (i.e., they are homozygous for the null allele of the gene) and are thus devoid of GSTM1 activity. The GSTMI null genotype frequency has been reported to show marked ethnic variation (51). Individuals lacking GSTM1 could be at a greater risk for developing lung cancer due to deficient detoxification processes; this notion is supported by recent studies (52).…”

“…There are, however, several putative confounding factors that are known to affect the phenotype such as environmental exposures, nutrition, and differences in smoking habits (56). In recent genotyping studies using PCR assays (51), no association has been found between null genotype and lung adenocarcinoma, but a tendency for an association between the GSTMI genotype and squamous cell carcinoma has been reported (57)(58)(59). GSTT1 Recently a GST null phenotype unrelated to the GSTMI was described for the glutathione-dependent detoxification of naturally occurring monohalomethanes.…”

Occupational history and genetic N-acetyltransferase polymorphism of urothelial cancer patients in Leverkusen, Germany

“…In this context, environmental tobacco smolce should also be considered (35) in that it contains at least 17 different mono-and bicyclic aromatic amines, including 2-naphthylamine and 4-aminodiphenyl (36). 011 the other hand, recent studies on the polyrnorphisrn of the huinan glutathione transferase GSTM1 (37) and its relevance to human lung (38) and bladder (39) cancer have introduced the concept that the GSTMl gene ought to have a protective role in tobacco-induced bladder cancer, possibly through increased detoxification of biologically reactive i~lternledlates of polycyclic aromatic hydrocarbons.…”

Genetic monitoring of human polymorphic cancer susceptibility genes by polymerase chain reaction: application to glutathione transferase mu.

“…In order to detect the GT p. sequence polymorphism by PCR, we used oligonucleotide primers that amplify exons 4-5 (8,12) or exons 6-7 of the GST1 gene. PCR amplification with these primer sets produced 273-bp or 215-bp bands on agarose gels from individuals with one or two copies of the GST1 allele, and no visible band if the individual was homozygously deleted.…”