Polymorphisms of glutathione S-transferase M1, T1 and P1 in patients with reflux esophagitis and Barrett's esophagus

J Hum Genet (2007) 52:527–534 DOI 10.1007/s10038-007-0148-z ORIGINAL ARTICLE Polymorphisms of glutathione S-transferase M1, T1 and P1 in patients with reflux esophagitis and Barrett’s esophagus Zdenek Kala Æ Jiřı́ Dolina Æ Filip Marek Æ Lydie Izakovicova Holla Received: 8 February 2007 / Accepted: 29 March 2007 / Published online: 3 May 2007
The Japan Society of Human Genetics and Springer 2007 Abstract Reflux esophagitis (RE) and Barrett’s esophagus (BE) belong to the most common esophageal complications of gastroesophageal reflux disease. Glutathione S-transferase (GST) enzymes play an important role in cellular protection against oxidative stress and toxic foreign chemicals. Therefore, we investigated the hypothesis that polymorphisms in genes for these detoxifying enzymes could influence susceptibility to RE and BE. GSTM1, GSTT1 and GSTP1 loci were analyzed by PCR-based methods in 64 patients with RE (and an additional group of 22 subjects with BE as the fourth grade of esophagitis) and 173 unrelated controls. There were no significant differences in the distributions of GSTM1 and GSTT1 genotypes between the controls and patients with RE or BE. Similarly, frequencies of GSTP1 alleles were non-significantly different between the control and RE groups. However, GSTP1 B allele carriers were more frequent among the patients with BE compared to those in the reflux esophagitis group (P = 0.04, OR = 2.10, 95% CI 0.99–4.44) and most significantly when compared to the controls (P = 0.0067, Pcorr < 0.05, OR = 2.56, 95%CI 1.30–5.05). Although the GSTM1 and GSTT1 genes did not show any relationship with reflux Z. Kala
F. Marek Department of Surgery, University Hospital Brno-Bohunice, Brno, Czech Republic J. Dolina Department of Gastroenterology, University Hospital Brno-Bohunice, Brno, Czech Republic L. Izakovicova Holla (&) Department of Pathophysiology, Medical Faculty, Masaryk University, Komenskeho nam. 2, 662 43 Brno, Czech Republic e-mail: disease, the GSTP1 gene might be one of the risk factors associated with susceptibility to RE, especially to BE. Keywords GERD
GSTs
Glutathione S-transferase
Polymorphism
Reflux esophagitis
Gene
Barrett’s esophagus Introduction Gastroesophageal reflux disease (GERD) is defined as a failure of the antireflux barrier, allowing abnormal reflux of gastric contents into the esophagus. Profound knowledge of the ethiology of GERD is limited due to a scarcity of valid population-based data of sufficient statistical power. Furthermore, many intrinsic (TLESR, delayed gastric emptying, etc.) and extrinsic factors (environmental factors, such as tobacco smoking, alcohol drinking, coffee and tea consumption or regular use of non-steroidal anti-inflammatory drugs, etc.) exist. A population-based study comparing reflux symptoms in monozygotic and dizygotic twins showed that also genetic factors might contribute to the ethiology by 30% (Cameron et al. 2002). Approximately 50% of patients with GERD develop esophagitis. The fourth grade of esophagitis includes strictures, ulcerations and Barrett’s esophagus (BE). Patients with BE have a 30–125 times greater risk of developing adenocarcinoma of the esophagus (Hameeteman et al. 1989; Spechler et al. 1984; Pera et al. 1993). Recent studies reported that interactions between the environmental factors and genetic variations of enzymes involved in the detoxification of oxygen radicals through the binding and transport of harmful compounds may represent one of the possible mechanisms of the carcinogenic process (Fitzgerald 2005). These enzymes include glutathione S- 123 528 transferases (GSTs) that are involved in the conjugation of a wide range of electrophilic substances with glutathione, thus facilitating detoxification and further metabolisation and excretion. They can also metabolize tobacco-related carcinogens (Berhane et al. 1994). In addition, the relation between tobacco smoking and reflux symptoms was previously reported (Nilsson et al. 2004). GSTs form a supergene family of enzymes involved in the phase II detoxification of toxins and enzymes (Brabender et al. 2002). GSTs comprise four main classes: A, M, P and T. They are present in many species and tissues and also in the epithelial tissues of the human gastrointestinal tract (Lieshout et al. 1999). Among them, GSTP1 enzyme is the most important form in the esophagus (Brabender et al. 2002). Previously, polymorphism in the GSTP1 gene on chromosome 11q13 was identified with six common phenotypes resulting from homo- and heterodimeric combinations of GSTP1*A, GSTP1*B and GSTP1*C (Ali-Osman et al. 1997). The transition changed codon 105 from ATC (Ile) in GSTP1*A to GTC (Val) in GSTP1*B and GSTP1*C and also codon 114 from GCG (Ala) to GTG (Val) in GSTP1*C. Both amino acid changes are in the electrophile-binding active site of the GSTP1 enzyme, and GSTP1-1 isoforms have been shown to possess different enzymatic activities (Hu et al. 1997; Watson et al. 1998; Zimniak et al. 1994). Decreased GSTP1 enzyme activity has been detected in BE, suggesting that these alterations may contribute to an increased cancer risk in this disease (Brabender et al. 2002). The most important polymorphism encodes a partial gene deletion at the GSTM1 locus on chromosome 1p13.3 (GSTM1 null genotype) resulting in the complete absence of GSTM1 enzyme activity (Garte et al. 2001). At the GSTT1 locus on chromosome 22q11.2, the GSTT1 null genotype represents a partial gene deletion and is associated with the absence of functional activity of the GSTT1 enzyme. The frequency of the GSTM1 and GSTT1 null genotypes are approximately 50 and 20% in the Caucasians (Garte et al. 2001). Both null genotypes have been reported to enhance the risk of developing gastric, colorectal or lung cancer (Lai et al. 2005; Holley et al. 2006), probably due to a low ability to detoxify several xenobiotics and a decreased defense toward oxidative stress and free radicalmediated cellular damage. In vivo studies have shown that also Helicobacter pylori causes oxidative damage and that H. pylori eradication attenuates oxidative stress in human gastric mucosa (Pignatelli et al. 2001). ROS (reactive oxygen species) are believed to be involved in inflammation, expression of oncogenes and cell proliferation. The GST activity was lower before the eradication of H. pylori compared to afterwards, and the GSH level was significantly higher after the eradication of this bacterium. This demonstrates 123 J Hum Genet (2007) 52:527–534 the loss of a detoxification mechanism of GST by H. pylori infection (Wang et al. 2000). So, the GST polymorphisms, single and/or in combination, are associated with compromised antioxidant capacity, especially in the presence of H. pylori infection, and therefore may be considered an additional risk factor for cancers, determining interindividual differences in susceptibility. Although several studies have been undertaken to examine the association between (...truncated)