Julie Alldersea

Glutathione S-transferase GSTM1 phenotypes and protection against cutaneous tumours

Multiple allelism at loci encoding detoxicating enzymes is associated with cancer risk. We have studied genetic variation at the glutathione S-transferase GSTM1 locus to see whether phenotypes confer altered susceptibility to basal cell carcinoma (BCC), squamous cell carcinoma (SCC), malignant melanoma (MM), or multiple skin tumours of different histological types. The frequency of GSTM1 null in cases and controls (52%) was similar, except for patients with two or more tumours of different types (71%, p = 0.033). GSTM1 A/B was reduced in frequency (p < 0.05) in patients with single or multiple BCC. Thus GSTM1 A/B may be protective, and effectiveness of detoxication may be a factor determining susceptibility to skin cancer.

Polymorphism in cytochrome P450 CYP2D6, CYP1A1, CYP2E1 and glutathione S-transferase, GSTM1, GSTM3, GSTT1 and susceptibility to tobacco-related cancers: studies in upper aerodigestive tract cancers.

Glutathione S-transferase GSTM1, GSTM3 and GSTT1 and cytochrome P450 CYP2D6, CYP1A1 and CYP2E1 loci are susceptibility candidates for cancers of the upper aerodigestive tract because putatively protective and risk genotypes have been identified from studies in other diseases associated with alcohol and tobacco consumption. We describe genotype frequencies in 398 oral, pharyngeal and laryngeal squamous cell carcinoma patients and 219 control individuals. Of the genotypes presumed to be protective, only GSTM1 A/B influenced susceptibility; the GSTM1 A/B frequency was lower in the patients than the control individuals both before [odds ratio = 0.3, 95% confidence interval (CI) 0.1-0.7] and after correction for imbalances in age, sex, smoking and alcohol consumption (odds ratio = 0.2, 95% CI 0.1-0.5). Of the putatively risk genotypes, GSTM3 AA, previously associated with susceptibility to skin cancer, was higher in the cases (odds ratio = 1.6, 95% CI 1.1-2.4). Dividing cases into oral/pharyngeal and laryngeal squamous cell carcinoma showed the GSTM3 AA frequency was higher in laryngeal squamous cell carcinoma than control individuals (odds ratio = 1.6, 95% CI 1.1-2.5) and the difference between control individuals and oral/pharyngeal squamous cell carcinoma approached significance (odds ratio = 1.7, 95% CI 1.0-2.8). The putatively protective GSTM3 BB genotype was lower in patients with glottic (1.0%) than supraglottic (3.0%) squamous cell carcinoma. We identified no differences between patients and control individuals in the frequencies of presumed risk genotypes (e.g. CYP2D6 EM, CYP1A1 m1/m1, CYP1A1 Ile/Ile, CYP2E1 DD, CYP2E1 c1c1, GSTT1 null) or, interactions between genotypes and smoking or alcohol consumption. We conclude, first, that mu class glutathione S-transferase influence risk of upper aerodigestive tract cancers thereby complementing studies in skin cancer patients showing GSTM1 A/B is protective, while GSTM3 AA moderately increases risk. The influence of GSTM1 A/B, but not GSTM1 A or GSTM1 B (mostly heterozygotes with GSTM1*0) suggests that two expressed alleles may attenuate risk. While we found immunohistochemical evidence of GSTM3 expression in the cilia lining the larynx, the biochemical consequences of the polymorphism are unclear. Indeed, the influence of the gene may reflect linkage disequilibrium with another gene. However, we did not find an association with GSTM1 genotypes. Second, we conclude that the CYP2D6, CYP2E1, CYP1A1 and GSTT1 alleles studied, although putatively good candidates, either do not determine the effectiveness of detoxification of tobacco-derived carcinogens in the upper aerodigestive tract or, that chronic consumption of tobacco and alcohol overwhelms enzyme defences, irrespective of genotype.

The glutathione S-transferase GSTP1 polymorphism: effects on susceptibility to oral/pharyngeal and laryngeal carcinomas.

We have examined the hypothesis that the polymorphic, glutathione S-transferase GSTP1 gene is a susceptibility candidate for squamous cell cancer of the oral/pharynx and larynx. We describe GSTP1 genotype frequencies in 380 cases and 180 controls. We found a lower frequency of GSTP1 AA in the oral/pharyngeal cases compared with controls (p = 0.003, odds ratio = 0.47) after correction for age and gender. We used an immunohistochemical approach to show widespread expression of the GSTP1 subunit throughout the pharynx and larynx. In uninfiltrated tissue, strong positivity was found throughout the squamous cell epithelium with the exception of the basal cell layer. The cilia of the respiratory epithelium of the larynx also showed positivity for GSTP1. In tumour tissue, expression of GSTP1 was similar in pharyngeal and laryngeal samples. These data are the first to show that polymorphism at GSTP1 mediates susceptibility to squamous cell cancer of the upper aerodigestive tract. No significant interactions were identified between GSTP1 and GSTM1, GSTM3, GSTT1 and the cytochrome P450 CYP1A1, CYP2D6 and CYP1A1 genotypes.

Glutathione S-transferase polymorphisms in MS Their relationship to disability

Background: Oxidative stress has been implicated in inflammatory demyelination. The glutathione S-transferase (GST) supergene family encodes isoenzymes that appear to be critical in protection against oxidative stress. Certain GST loci are polymorphic, demonstrating alleles that are null (GSTM1/GSTT1), encode low activity variants (GSTP1), or are associated with variable inducibility (GSTM3). Objectives: To investigate the association between clinical outcome in MS and allelic variants of GSTM1, GSTM3, GSTT1, and GSTP1. Methods: Four hundred patients with clinically definite MS were studied. Disability was measured using the Kurtzke Expanded Disability Status Scale (EDSS). Disability was graded as mild (EDSS 0–4), moderate (4.5–5.5), or severe (EDSS 6–10). PCR-based genotyping was performed using DNA extracted from lymphocytes. Significant associations between GST genotypes and clinical outcome were corrected for gender, onset age, and disease duration using logistic regression. Results: We found that the GSTM3 AA genotype was associated with severe disability in patients with a disease duration of more than 10 years (p = 0.027, n = 177, OR = 2.4, 95% CI = 1.1–5.0). Homozygosity for both GSTM1*0 and GSTP1*Ile105 containing allele was associated with severe disability in patients with a disease duration greater than 10 years (p = 0.022, n = 179, OR = 5.0, 95% CI = 1.3–19.8). Conclusions: Our results suggest that long-term prognosis in MS is influenced by a genetically determined ability to remove the toxic products of oxidative stress.

Association of polymorphism in glutathione S-transferase loci with susceptibility and outcome in rheumatoid arthritis: comparison with the shared epitope

OBJECTIVE To determine whether glutathione S-transferase GSTM1, GSTM3, GSTT1, and GSTP1 genotypes influence susceptibility or outcome in rheumatoid arthritis (RA). METHODS 277 RA patients were compared with 577 controls to examine any associations between GST genotypes and susceptibility to RA. The effect of genotypes on outcome (Larsen and functional scores) and time integrated acute phase responses (erythrocyte sedimentation rate and C reactive protein) was assessed in 122 patients with disease duration of 5–10 years. GST and HLA-DRB1 genotypes were determined using polymerase chain reaction based assays. Data were analysed using multiple regression analysis with correction for age, sex, disease duration, and the DRB1 associated shared epitope (SE) and rheumatoid factor (RF) positivity where appropriate. RESULTS TheGSTM1*A/*B genotype was less common in RA cases (3 of 276) than in controls (22 of 591) (exact p=0.047), though significance was lost when adjustment was made for multiple comparisons. The Larsen score was higher (p=0.039) in the GSTM1 null patients (89.9) than those with other GSTM1 genotypes (74.7), and this was independent of the SE. Again, correction for multiple testing resulted in loss of significance. The difference in Larsen scores between patients homozygous or negative for the SE (87.9v 74.3) was similar to that between GSTM1 null and non-null patients. No associations between GSTM3 or GSTT1 genotypes and disease markers were identified although the association between GSTP1*B/*B and Larsen score approached significance (p=0.096). CONCLUSION It is proposed that certain GSTs may influence susceptibility and radiological progression in RA and that this is independent of the effect of the HLA-DRB1 associated SE. The mechanism for this effect is presumed to be because of differences in the ability of various GST enzymes to utilise the cytotoxic products of oxidant stress. Although significance was lost after correction for multiple testing, the data indicate that further studies may be of value in RA to determine the influence of the GST and other genes involved in cellular protection against oxidative stress.

Susceptibility to multiple cutaneous basal cell carcinomas: significant interactions between glutathione S-transferase GSTM1 genotypes, skin type and male gender

The factors that determine development of single and multiple primary cutaneous basal cell carcinomas (BCCs) are unclear. We describe a case-control study firstly, to examine the influence of allelism at the glutathione S-transferase GSTM1 and GSTT1 and cytochrome P450 CYP2D6 loci on susceptibility to these tumours and, secondly, to identify interactions between genotypes and relevant individual characteristics, such as skin type and gender. Frequency distributions for GSTM1 genotypes in cases and controls were not different, although the frequency of GSTM1 A/B was significantly lower (P = 0.048) in the multiple BCCs than in controls. We found no significant differences in the frequencies of GSTT1 and CYP2D6 genotypes in cases and controls. Interactions between genotypes were studied by comparing multinomial frequency distributions in mutually exclusive groups. These identified no differences between cases and controls for combinations of the putatively high risk GSTM1 null, GSTT1 null, CYP2D6 EM genotypes. Interactions between GSTM1 A/B and the CYP2D6 PM and GSTT1-positive genotypes were also not different. Frequency distributions of GSTM1 A/B with CYP2D6 EM in controls and multiple BCCs were significantly different (P = 0.033). The proportion of males in the multiple BCC group (61.3%) was greater than in controls (47.0%) and single BCC (52.2%), and the frequency of the combination GSTM1 null/male gender was significantly greater in patients with multiple tumours (P = 0.002). Frequency distributions of GSTM1 null/skin type 1 were also significantly different (P = 0.029) and the proportion of subjects who were GSTM1 null with skin type 1 was greater (P = 0.009) in the multiple BCC group. We examined the data for interactions between GSTM1 null/skin type 1/male gender by comparing frequency distributions of these factors in the single and multiple BCC groups. The distributions were almost significantly different (exact P = 0.051). No significant interactions between GSTT1 null or CYP2D6 EM and skin type 1 were identified. Comparisons of frequency distributions of smoking with the GSTM1 null, GSTT1 null and CYP2D6 EM genotypes identified no differences between patients with single and multiple tumours.

SUSCEPTIBILITY TO ULCERATIVE COLITIS AND CROHN'S DISEASE: INTERACTIONS BETWEEN GLUTATHIONE S-TRANSFERASE GSTM1 AND GSTT1 GENOTYPES

Abstract The polymorphic glutathione S-transferase GSTM1 and GSTT1 loci are attractive candidates for susceptibility to ulcerative colitis and Crohns disease because their enzymes catalyse the detoxification of products of oxidative stress and tobacco-derived carcinogens. We have tested this hypothesis by comparing genotype frequencies in 245 ulcerative colitis, 112 Crohns disease patients and 373 controls. Polymerase chain reaction approaches were used to identify the GSTM1 A, GSTM1 B, GSTM1 A B , GSTM1 null and GSTT1 null and GSTT1 positive genotypes. The ages and smoking characteristics of ulcerative colitis and Crohns patients were significantly different. Frequencies of GSTM1 genotypes in distal and total ulcerative colitis and controls were not different though frequency of GSTT1 null was significantly greater in the total disease (34.6%) than in the distal disease (17.5%) and control groups (17.7%). The age-corrected odds ratio for GSTT1 null was 2.40 (P = 0.0077). The frequency of GSTT1 null in the Crohns patients and controls was similar though the frequency of GSTM1 B (7.3%) was significantly reduced compared with controls (15.0%) and patients with distal ulcerative colitis (19.9%). These data indicate that GSTM1 and GSTT1 mediate risk of certain inflammatory pathologies but are not general markers of susceptibility to such diseases. They also contribute to data showing that susceptibility to distal and total ulcerative colitis and Crohns disease are influenced by different genes.

The association of maternal but not paternal genetic variation in GSTP1 with asthma phenotypes in children

Maternal factors including atopy and smoking during pregnancy are associated with asthma risk during childhood. Suggested mechanisms include transmission of specific maternal alleles and maternal influences on the intrauterine environment. We have previously shown that polymorphism in glutathione S-transferase, GSTP1 is associated with airway hyperresponsiveness (AHR) and atopy in adults. We now hypothesise that GSTP1 genotypes in the mother and child, but not the father, mediate asthma phenotypes in the child. One hundred and forty-five Caucasian families were recruited via an asthmatic proband aged 7-18 years. Atopy and asthma were assessed using a questionnaire, skin prick testing, serum IgE, spirometry and methacholine challenge (PC20, dose-response slope--DRS). GSTP1 genotyping was determined using PCR. GSTP1 Val105/Val105 genotype in the child was associated with a reduced risk of atopy (P = 0.038) and AHR (PC20, P = 0.046; DRS, P = 0.032). In mothers (P = 0.014) but not fathers (P = 0.623), Val105/Val105 was associated with a reduced risk of AHR in the child. We have identified, for the first time, an association between maternal genotype and the childs asthma phenotype that appears not to be due to transmission of specific maternal alleles. This preliminary data supports the view of in utero effects of maternal genotype and adds new insights into the possible mechanisms by which maternal factors may influence development of childhood asthma.

Vitamin D receptor gene polymorphism is associated with reduced disability in multiple sclerosis.

Ultraviolet radiation (UVR) may contribute to multiple sclerosis (MS) outcome by a mechanism involving vitamin D and the vitamin D receptor (VDR). In 512 patients with MS duration of 10 or more years, we studied the association of VDR single nucleotide polymorphisms (A/G1229, C/G3444, G/A3944, CC20965, CC30056, F/f30875, C/T48200, T/t65013) with outcome or disability. ff30875 frequency was lower in cases with EDSS ≥ 6.0 than with scores < 6.0 (odds ratio = 0.38, 95% CI = 0.20–0.70). The association of ff30875 with outcome was not mediated by cumulative exposure to UVR as assessed by questionnaire; low exposure (odds ratio = 0.42, 95% CI = 0.14–1.34) and high exposure (odds ratio = 0.34, 95% CI = 0.16–0.73).

Polymorphism in Detoxifying Enzymes and Susceptibility to Skin Cancer

ates, isomerization of urocanic acid and activation of a surprising range of cytokine genes within keratinocytes. The DNA photoproducts (1 8) and UVB-generated oxygen intermediates (19) have been implicated as damaging to cutaneous immunity. The possibility exists that polyrnorphisms at loci that encode excision and repair genes or at loci regulating free radical quenching may exist and could have a profound effect on cutaneous immunity. Similarly, polymorphisms at cytokine gene loci may contribute to UVB-S. Finally, UVB radiation produces multiple, mechanistically distinct immune aberrations. Locally, at the irradiated site, UVB radiation (1) impairs induction of CH, (2) promotes hapten-specific tolerance and (3) creates a sustained immunosuppressive microenvironment (20). Systemically, UVB radiation (1) impairs both delayed and CH to a variety of antigens (21) and (2) induces active, nonspecific unresponsiveness. Our studies have revealed genetics factors operating in only one of these aberrations, but we suspect that, in time, other polymorphic genetic factors will be identified that contribute to the damaging immune effects of UVB radiation and thereby alter an individual’s risk of developing sunlight-induced skin cancer.