Progression of cervical intraepithelial neoplasia to cervical cancer: interactions of cytochrome P450 CYP2D6 EM and glutathione s-transferase GSTM1 null genotypes and cigarette smoking.

The factors that determine progression of cervical intraepithelial neoplasia (CIN) to squamous cell carcinoma (SCC) are unknown. Cigarette smoking is an independent risk factor for cervical neoplasia, suggesting that polymorphism at detoxicating enzyme loci such as cytochrome P450 CYP2D6 and glutathione S-transferase GSTM1 may determine susceptibility to these cancers. We have studied the frequencies of genotypes at these loci in women suffering low-grade CIN, high-grade CIN and SCC. A non-cancer control group was provided by women with normal cervical histology suffering menorrhagia. Comparison of the frequency distributions of the CYP2D6 PM, HET and EM genotypes (G-->A transition at intron 3/exon 4 and base pair deletion in exon 5) revealed no significant differences between the menorrhagia and SCC groups. Frequency distributions in the menorrhagia group, however, were significantly different (P < 0.04) from those in the low- and high-grade CIN groups. Thus, the proportion of EM was significantly larger (P < 0.03) and of HET generally lower. We found that the frequency of GSTM1 null in the menorrhagia and case groups was not significantly different. Interactive effects of enzyme genotypes with cigarette smoking were studied by comparing the multinomial frequency distributions of CYP2D6 EM/GSTM1 null/smoking over mutually exclusive categories. These showed no significant differences between the menorrhagia group and SCC or low-grade CIN groups. The frequency distribution in high-grade CIN, however, was significantly different to that in the menorrhagia group and in both SCC and low-grade CIN groups. This study was identified, for the first time, an inherited characteristic in women with high-grade CIN who appear to be at reduced risk of SCC. Thus, women with CYP2D6 EM who smoke have increased susceptibility to high-grade CIN but are less likely to progress to SCC, possibly because they effectively detoxify an unidentified chemical involved in mediating disease progression

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

Use of site-directed mutagenesis of allele-specific PCR primers to identify the GSTM1 A, GSTM1 B, GSTM1 A,B and GSTM1 null polymorphisms at the glutathione S-transferase, GSTM1 locus.

We describe the identification of the GSTM1 null, GSTM1 A, GSTM1 B and GSTM1 A,B polymorphisms at the glutathione S-transferase GSTM1 locus using a single-step PCR method. Target DNA was amplified using primers to intron 6 and exon 7 with site-directed mutagenesis being used to introduce a restriction site in DNA amplified from GSTM1 *A, thereby allowing differentiation of this allele and GSTM1 *B. The accuracy of this approach in identifying the GSTM1 A, GSTM1 B, GSTM1 A,B and GSTM1 null polymorphisms was confirmed by comparison with, firstly, an established PCR method that distinguishes GSTM1 *0 homozygotes from individuals with the other GSTM1 genotypes and, secondly, GSTM1 phenotypes determined using chromatofocusing

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. Immunohisto-chemical 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 GSTMl-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

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