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A A Fryer

Publications and source records attributed to A A Fryer.

At least 91 records · Page 5Linked to original sources

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.

Aged↗

Polymorphism within the cyclin D1 gene is associated with prognosis in patients with squamous cell carcinoma of the head and neck.

We have examined the correlation of a frequent A/G polymorphism within exon 4 of the cyclin D1 gene (CCND1) with genetic susceptibility and clinical outcome in 384 patients with squamous cell carcinoma (SCC) of the head and neck. CCND1 genotype frequencies were similar in the cases and 191 controls. Furthermore, the CCND1 genotype was not associated with susceptibility to SCC of the larynx, pharynx, or oral cavity. The influence of the CCND1 genotype on clinical outcome was also assessed. We found no correlation between genotype and tumor size (T1-T4), the involvement of nodes at presentation, or patient age and gender. However, the distribution of CCND1 genotypes in cases with poorly differentiated tumors was significantly different to that in patients with well-/moderately differentiated tumors (P = 0.016; chi2(2) = 8.71). Homozygosity for CCND1*G (GG genotype) was associated with poorly differentiated tumors (G3). We used Cox's proportional hazards model to investigate the influence of the CCND1 genotype on disease-free interval. CCND1 GG was associated with reduced disease-free interval [P = 0.001; hazard ratio (HR) = 2.95; 95% confidence interval (CI) = 1.54-5.63]. This remained significant after correction for tumor differentiation (P = 0.013; HR = 2.34; 95% CI = 1.2-4.6) and tumor stage (P = 0.005; HR = 2.64; 95% CI = 1.34-5.19). Analysis of the data from patients with tumors at different sites showed that the CCND1 GG genotype was associated with reduced disease-free interval in laryngeal (P = 0.004; HR = 3.63; 95% CI = 1.44-8.83) and pharyngeal (P = 0.006; HR = 3.48; 95% CI = 1.43-8.46) tumors. This is the first report of an association between CCND1 polymorphism and prognosis in SCC of the head and neck. These data show that the CCND1 GG genotype is an independent prognostic indicator of disease-free interval and supports initial observations in non-small cell lung cancer, that polymorphism within CCND1 influences tumor behavior.

Adult↗

Association of glutathione S-transferase GSTM1 and GSTT1 null genotypes with clinical outcome in epithelial ovarian cancer.

Epithelial ovarian cancer is generally associated with a poor outcome, although the mechanisms that determine survival and progression-free interval (PFI) are unclear. Data from ovarian tumors showing associations between (a) null genotypes at the glutathione S-transferase GSTM1 and GSTT1 loci and expression of p53 protein and (b) outcome and expression of p53 suggest that polymorphism at these loci is a factor determining outcome. Accordingly, we have studied the association between the GSTM1 null and GSTT1 null genotypes and survival and PFI in 148 women with epithelial ovarian cancer. Although we did not find an association between individual genotypes and outcome, women with both GSTM1 null and GSTT1 null genotypes demonstrated poorer survival (P = 0.001) and reduced PFI (P = 0.003). Thus, no cases with both these genotypes survived past 42 months postdiagnosis. In contrast, 43% of the women without this combination survived beyond this time. Because response to chemotherapy is a major factor determining outcome in ovarian cancer, we also examined the data for associations between the glutathione S-transferase genotypes and response to such treatment. Thus, in 78 patients treated with chemotherapy, the combination of GSTM1 null and GSTT1 null was associated with unresponsiveness to primary chemotherapy (P = 0.004); none of the eight patients with both these genotypes responded, compared with 38 of 70 (54%) of patients with other genotype combinations. The effect of the combination of genotypes on survival and PFI was lost in a multivariate model that included response to chemotherapy as a confounding factor. This suggests that the combination of GSTM1 null/GSTT1 null is associated with outcome because of its influence on response to chemotherapy. These preliminary findings may provide a basis for the selection of patients for treatment with chemotherapeutic agents.

Adolescent↗

Truncal site and detoxifying enzyme polymorphisms significantly reduce time to presentation of further primary cutaneous basal cell carcinoma.

Basal cell carcinoma (BCC) is the commonest cancer in Caucasians. Its incidence is rising and many patients develop multiple primary tumours at separate sites. Factors determining time between first primary tumour presentation and the next new primary lesion are unclear. We used Cox's proportional hazards model to study, in 856 Caucasians, the influence of tumour site, individual characteristics and polymorphism in glutathione S-transferase (GSTM1, GSTT1) and cytochrome P450 (CYP2D6, CYP1A1) loci on time to next primary tumour presentation. More than one tumour at first presentation (P <0.0001, hazard ratio 2.72) and GSTT1 null (P = 0.028, hazard ratio 1.74) were associated with decreased time to next primary tumour presentation. Significant two-factor interactions, corrected for number of tumours at presentation, were identified between a truncal tumour at first presentation and each of male gender, GSTM1 null and CYP2D6 EM (P <0.003, hazard ratios 3.09-3.82). In each of these cases, all patients with the risk combination demonstrated further separate tumours within 5 years of first presentation. Thus, patients with a truncal tumour at first presentation, especially males and those presenting with more than one lesion have a significantly decreased time to presentation of further tumours and should receive more meticulous follow-up. Polymorphism in GSTM1 and CYP2D6 also influences the rate of new primary tumour accrual giving insights into the link between ultraviolet exposure and multiple tumour development.

Aged↗

Truncal tumor site is associated with high risk of multiple basal cell carcinoma and is influenced by glutathione S-transferase, GSTT1, and cytochrome P450, CYP1A1 genotypes, and their interaction.

Basal cell carcinoma (BCC) places increasing burdens on clinicians; incidence is rising and patients may develop multiple primary tumors. Although UV exposure is critical, many patients develop tumors at less-exposed sites, such as the trunk, suggesting a genetic predisposition. We previously showed that polymorphism in loci encoding the detoxifying enzymes, glutathione S-transferase (GSTM1, GSTM3, GSTT1) and cytochrome P450 (CYP2D6, CYP1A1) influences susceptibility to BCC. We now describe a case-control approach in 345 patients with BCC that examines the role of these polymorphisms and patient characteristics (age, gender, skin type, hair color, eye color, smoking, occupation) in determining susceptibility to truncal tumors. GST and CYP genotypes were identified using polymerase chain reaction-based methods. Patients with one or more truncal tumors were significantly younger (p = 0.0170) than those with no truncal tumors. Male gender also appeared more common in the truncal tumor group, although this did not achieve significance (p = 0.0925). Patients whose first tumor was truncal had significantly more tumors (p = 0.0297). GSTT1 null (p = 0.0245, odds ratio 2.24) and CYP1A1 Ile/Ile (p = 0.0386, odds ratio 2.86) were associated with truncal site after correction for age and gender. The combination, GSTT1 null and CYP1A1 Ile/Ile, was particularly significant (p = 0.0059, odds ratio = 2.95). These effects were present after correction for tumor numbers. These data show first, patients with truncal tumors constitute a high-risk group for BCC, second, a significant genetic influence on BCC site, and third, a significant interaction between GSTT1 and CYP1A1 genotypes.

Aged↗

Risk factors for basal cell carcinoma in the UK: case-control study in 806 patients.

Basal cell carcinoma (BCC) is the commonest malignant neoplasm in white people. We present a large UK case-control study in which conditional logistic regression analysis of age-matched and gender-matched data sets was used to compare, first, cases with controls (n = 403) and second, patients having multiple BCC with those having a single BCC (n = 278). Eye/hair colour, occupation, skin type, social class, tumour site at presentation and smoking history were assessed. Social class 1/2, skin type 1, red/blonde hair and blue/green eyes were all related to BCC risk, social class most strongly (odds ratio 2.36, P = 0.007). Truncal site at presentation was a risk factor for the development of multiple BCC (odds ratio 4.03, P = 0.002). These data support the view that genetically mediated differences in ultraviolet responsiveness are important in BCC, though the scale of their effect is small. They may be exploitable in primary and secondary prevention as well as giving insights into pathogenesis. In particular, the fact that patients presenting with a truncal tumour are at increased risk of further BCC suggests that intermittent exposure in genetically predisposed individuals may contribute to a cancer susceptibility syndrome.

Basal Cell Carcinoma↗

Polymorphism at the glutathione S-transferase locus GSTM3: interactions with cytochrome P450 and glutathione S-transferase genotypes as risk factors for multiple cutaneous basal cell carcinoma.

The influence of polymorphism in the glutathione S-transferase, GSTM3 gene on susceptibility to cutaneous basal cell carcinoma (BCC) has been investigated. We have reported previously two GSTM3 alleles, GSTM3*A and GSTM3*B, distinguished by a recognition motif for the YY1 transcription factor in GSTM3*B. In this study, immunohistochemistry was used to identify GSTM3 expression in the epidermis of skin samples from 11 controls and 9 patients with BCC. A PCR method was used to identify GSTM3*A and GSTM3*B and thereby the GSTM3 AA, GSTM3 AB, and GSTM3 BB genotypes in 300 controls and 286 Caucasians with 1-35 primary BCCs. Genotypes at GSTM1, GSTT1, and the cytochrome P450 CYP1A1 and CYP2D6 loci were also determined. Frequencies of GSTM3, GSTM1, GSTT1, CYP2D6, and CYP1A1 genotypes in the cases and controls were not different. Dividing the BCC cases into groups of 92 patients with 1 lesion and 194 patients with 2-35 lesions showed that the frequencies of GSTM3 BB (2.6%) and GSTM1 A/B (1.3%) in the group with 2-35 tumors were almost significantly lower than in the group with 1 lesion (7.6%, exact P = 0.0601, chi 2(1) = 3.390; 6.5%, exact P = 0.055, chi 2(1) = 4.946, respectively). Within the cases with 2-35 tumors, a Poisson regression model was used to identify genotypes, characteristics such as skin type, and interactions between genotypes and characteristics associated with increasing numbers of tumors. This showed, after correction for male gender and age, that GSTM3 AA was not associated with risk of increased numbers of tumors, although in combination with skin type 1, GSTM1 null, and CYP1A1 m1m1, the genotype did confer increased risk (P < 0.001, rate ratio, 2.058; P < 0.001, rate ratio, 1.606; P < 0.001, rate ratio, 1.470 respectively). The data suggest that, like other allelic GST, GSTM3 influences cancer risk. As GSTM3 AA was associated with increased tumor numbers, it appears that YY1 acts as an activator of the recognition motif in GSTM3*B.

Aged↗

Epithelial ovarian cancer: influence of polymorphism at the glutathione S-transferase GSTM1 and GSTT1 loci on p53 expression.

The importance of polymorphism in the glutathione S-transferase GSTM1, GSTT1 and, cytochrome P450, CYP2D6 loci in the pathogenesis of epithelial ovarian cancer has been assessed in two studies; firstly, a case-control study designed to determine the influence of these genes on susceptibility to this cancer, and secondly, the putative role of these genes in the protection of host cell DNA has been studied by comparing p53 expression in patients with different GSTM1, GSTT1 and CYP2D6 genotypes. The frequencies of GSTM1, GSTT1 and CYP2D6 genotypes in 84 cases and 325 controls were not different. Immunohistochemistry was used to detect p53 expression in 63 of these tumours. Expression was found in 23 tumours. Of the patients demonstrating immunopositivity, 20 (87%) were GSTM1 null. The frequency distributions of GSTM1 genotypes in p53-positive and -negative samples were significantly different (P = 0.002) and those for GSTT1 genotypes approached significance (exact P = 0.057). The proportion of patients with both GSTM1 null and GSTT1 null was also significantly greater in the immunopositive (4/22) than in the immunonegative group (1/40) (P = 0.0493). Single-strand conformational polymorphism (SSCP) analysis was used to detect mutations in the 23 tumour samples demonstrating p53 positivity. A shift in electrophoretic mobility of amplified fragments was found in 11 patients (exons 5, 6, 7 and 8) and these exons were sequenced. In eight samples a mutation was found. No SCCP variants were identified in the other 12 immunopositive patients. Sequencing of exons 4-9 of p53 from these tumours resulted in the detection of mutations in two patients (exons 5 and 7). Thus, in 23 patients who demonstrated immunopositivity, p53 mutations were found in nine patients with GSTM1 null (90.0%). In the 13 patients in whom no mutations were identified, 11 were GSTM1 null (84.6%). The data show that overexpression of p53 is associated with the GSTM1 null genotype. We propose the data are compatible with the view that GSTM1 and GSTT1 are critical in the detoxification of the products of oxidative stress produced during the repair of the ovarian epithelium. Thus, failure to detoxify products of this stress may result in damage to various genes in the host cell, including to p53, resulting in persistent expression of mutant protein. In other patients, oxidative stress effects damage to various genes, but not including p53, resulting in overexpression of wild-type p53.

Case-Control Studies↗

Glutathione S-transferase GSTT1 genotypes and susceptibility to cancer: studies of interactions with GSTM1 in lung, oral, gastric and colorectal cancers.

Allelism in glutathione S-transferase GSTM1 and GSTT1 has been suggested as a risk factor in various cancers. Accordingly, we describe a group of case-control studies carried out to identify associations between GSTT1 genotypes and susceptibility to lung, oral, gastric and colorectal cancers. The frequencies of the putatively high risk GSTT1 null genotype were not increased in the lung, oral or gastric cancer cases compared with controls but the frequency of this genotype was significantly increased (P = 0.0011, odds ratio = 1.88) in the colorectal cancer cases. No significant interactions between the GSTT1 and GSTM1 null genotypes types were identified in the cancer groups studied. Indeed, no significant associations between GSTM1 genotypes and susceptibility were identified though further evidence was obtained that the protective effect of GSTM1*A and GSTM1*B is not equal. The data complement studies showing that GSTT1 null is associated with an increased susceptibility to total ulcerative colitis and suggests that this enzyme is important in the detoxification of unidentified xenobiotics in the large intestine.

Case-Control Studies↗

Multiple cutaneous basal cell carcinomas: glutathione S-transferase (GSTM1, GSTT1) and cytochrome P450 (CYP2D6, CYP1A1) polymorphisms influence tumour numbers and accrual.

The genetic factors that mediate the pathogenesis of multiple primary cutaneous basal cell carcinomas (BCC) are largely unclear. Thus, some patients suffer many BCC (>30) and/or rapid accrual (number of tumours/year from first presentation) of further lesions. We have studied, in 827 English Caucasians, the influence of polymorphism in carcinogen-metabolizing enzymes on susceptibility to this cancer. Accordingly, we describe, first, a cross-sectional analysis of the influence of GSTM1, GSTT1, CYP2D6 and CYP1A1 genotypes on tumour numbers, and secondly, a longitudinal analysis, in 169 of these cases, of the effect of these genes on tumour accrual. We have confirmed the expected importance of age and number of lesions at presentation, and male gender and skin type as risk factors. Furthermore, the cross-sectional analysis showed CYP1A1 m1m1 (P = 0.004; rate ratio 1.242) and CYP2D6 EM (P < 0.001, rate ratio 1.266) are associated with increased numbers of BCC. The longitudinal study showed, after adjustment for age and tumour number at presentation, that GSTT1 null (P < 0.001, rate ratio 2.677) and CYP2D6 EM (P < 0.001, rate ratio 2.154) were significant determinants of accrual while CYP1A1 Ile/Ile was associated with slower accrual than the Ile/Val and Val/Val genotypes (P = 0.008, rate ratio 0.690). We believe these are the first genetic factors to be associated with tumour accrual. No significant interactions between genotypes were identified, though the combinations GSTM1 null/skin type 1 (P < 0.001, rate ratio 2.702), CYP2D6 EM/male gender (P = 0.049, rate ratio 1.279) and CYP2D6 EM/blue+green eyes (P = 0.046, rate ratio 1.388) influenced tumour numbers. Previous studies indicate the importance of effective repair of UV-damaged DNA in the pathogenesis of multiple BCC; indeed the influence of GSTM1 may result from its ability to utilize 5'-hydroxymethyluracil. However, the finding that CYP2D6 and CYP1A1 influence tumour numbers and accrual indicates detoxification of unknown molecules is important and supports the view that factors other than UV are important in the pathogenesis BCC.

Adult↗

Allelism at the glutathione S-transferase GSTM3 locus: interactions with GSTM1 and GSTT1 as risk factors for astrocytoma.

We describe studies to assess the influence of polymorphism in the human glutathione S-transferase GSTM3 gene on susceptibility to high grade astrocytoma. Immunohistochemical studies using a GSTM3-specific antiserum identified expression of the GSTM3 subunit in astrocytes. The relative levels of expression of GSTM1 and GSTM3 in brain cytosols were determined after resolution of these enzymes using chromatofocusing. We found no differences in the level of GSTM3 activity in individuals with GSTM1 null and those with GSTM1-positive genotypes (GSTM1 A, GSTM1 B and GSTM1 A/B). A case-control study was performed to determine if GSTM3 alone or in combination with GSTM1 or GSTT1 influenced susceptibility to high grade astrocytoma. After correction for differences in age and gender, GSTM3 AA was not significantly different in cases compared with controls. No significant interactions between GSTM3 AA and GSTM1 null were identified. The significant interaction between GSTM3 AA and GSTT1 null appeared to result from the strength of the main effect (GSTT1 null). The data show that while GSTM3 is expressed in astrocytes and contributes significantly to total GST activity in human brain, it does not appear to influence susceptibility to high grade astrocytoma. Further, unlike lung, there appears to be no relationship between the level of GSTM3 activity in brain and GSTM1 genotype.

Alleles↗

[Initial results of glutathione-S-transferase GSTM1 and GSTT1 genotypes and genetic predisposition for laryngeal carcinoma].

BACKGROUND: While cigarette smoking and alcohol consumption have been linked to laryngeal carcinoma, the role of genetic factors in determining individual susceptibility is unknown. We describe the role of allelism at glutathione-S-transferase GSTM1, GSTT1, and cytochrome P 450 CYP2D6 loci in determining individual susceptibility to laryngeal squamous cell carcinoma. METHODS: Enzyme genotypes were determined using the polymerase chain reaction in 169 patients suffering T1-T4 laryngeal carcinoma and in 145 controls. RESULTS: While the frequency of the heterozygote GSTM1 A/B genotype was statistically significantly lower in the cases than controls, the frequency of the GSTT1 null genotype was higher in cases than controls. CONCLUSION: These initial data suggest that allelism at GST loci mediates susceptibility to squamous cell carcinoma of the larynx. Thus, GSTM1 A/B appears to be associated with a reduced risk while GSTT1 null confers increased risk. The findings are compatible with the view that genetic predisposition is important in determining risk of this cancer.

Adult↗

GSTM1 and CYP2D6 genotype frequencies in patients with pituitary tumours: effects on P53, ras and gsp.

We describe studies to determine if susceptibility to pituitary tumours is associated with the putatively high risk GSTM1 null and CYP2D6 EM genotypes. Frequency distributions of these genotypes were similar in cases and controls though the frequency of CYP2D6 PM and GSTM1 B tended to be lower (P = 0.072 and P = 0.095 respectively) in the tumour group. Immunopositivity for p53 was found in 18/97 tumours. In these samples GSTM1 null (39%) and CYP2D6 EM (56%) frequencies were not different to those in controls. The frequencies of CYP2D6 PM and GSTM1 B in the p53 immunonegative tumours tended to be lower (P = 0.055 and P = 0.1185 respectively) than in controls. Mutations in gsp and ras were studied using the polymerase chain reaction and allele specific oligonucleotide analysis. Eight of 19 somatotrophinomas demonstrated mutations in gsp; frequencies of GSTM1 null and CYP02D6 EM were similar to controls. No ras mutations were identified in 55-tumour studies. The data indicate the GSTM1 null and CYP2D6 EM genotypes are not associated with altered expression of p53 or, mutation of gsp and ras in these adenomas and, suggest the CYP2D6 PM genotype is associated with a reduced risk of pituitary adenomas and, that GSTM1*B confers greater protection than GSTM1*A.

Adult↗

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.

Aged↗