Pawel Rusin

Genetic polymorphisms in DNA base excision repair gene XRCC1 and the risk of squamous cell carcinoma of the head and neck

BackgroundThe genes of base excision repair (BER) pathway have been extensively studied in the association with various human cancers. We performed a case-control study to test the association between two common single nucleotide polymorphisms (SNPs) of XRCC1 gene with human head and neck squamous cell carcinoma (HNSCC).MethodsThe genotype analysis of Arg194Trp and Arg399Gln gene polymorphisms for 92 HNSCC patients and 124 controls of cancer free subjects, in Polish population were performed using the PCR-based restriction fragment length polymorphism (PCR-RFLP) with endonuclease Msp I.ResultsNo altered risk has been found individually for these SNPs, however haplotypes analysis showed high association with head and neck cancer. The highest frequency, according to wild-type of Arg194Arg and Arg399Arg genotypes, was identified for Arg194Trp-Arg399Arg haplotype (OR, 2.96; 95% CI, 1.01–8.80).ConclusionFinally, we identified the combined Arg194Trp-Arg399Arg genotype of base excision repair gene XRCC1 that was associated with HNSCC and may have an impact on identification of a high-risk cancer population.

Polymorphisms of the XRCC3 C722T and the RAD51 G135C genes and the risk of head and neck cancer in a Polish population

Genetic variations in DNA repair genes may affect an individuals susceptibility to head and neck cancer. We performed a case-control study to test the association between head and neck cancer risk and two polymorphisms: the C722T of the XRCC3 and the G135C of the RAD51-genes of DNA double strand break (DSB) repair by homologous recombination (HRR). Genotypes were determined by PCR-restriction fragment length polymorphism (PCR-RFLP). DNA was isolated from peripheral blood lymphocytes of a group of 288 patients consisting of 97 subjects with precancerous hyperplastic laryngeal lesions (PHLL) and 191 subjects with head and neck squamous cell carcinoma (HNSCC) as well as 353 healthy control donors. We found an association between PHLL and the 722CT (OR 6.67; 95% CI 3.02-14.74) as well as 722TT (OR 4.65; 95% CI 2.30-9.43) variants of the XRCC3 gene. Similar relation was observed between these genotypes and HNSCC (OR 2.59; 95% CI 1.61-4.16 and OR 5.54; 95% CI 3.22-9.52, respectively). Moreover, we also observed an association between PHLL (OR 6.04; 95% CI 3.69-9.90) and HNSCC (OR 6.04; 95% CI 3.69-9.90) and the 135GC variant of the RAD51 gene. The gene-gene interaction between XRCC3 and RAD51 polymorphic variants may contribute to higher prevalence of PHLL. The increased risk of this disease was observed in case of the combination of the 722CT/135GC (OR 3.81; 95% CI 1.55-9.75) as well as the 722TT/135GC genotypes (OR 5.33; 95% CI 1.96-14.47). The presence of the same genes combinations plays a part in higher probability of HNSCC occurrence (OR 2.42; 95% CI 1.22-4.79 for 722CT/135GC and OR 3.63; 95% CI 1.69-7.76 for 722TT/135GC). We also found an association between these XRCC3 or RAD51 polymorphic variants and smoking status in PHLL (ORs 2.85-10.28 and 1.82-7.35, respectively) and HNSCC patients (ORs 2.94-13.93 and 1.36-3.94, respectively) as well as alcohol intake among PHLL (ORs 3.44-6.12 and 3.52-8.43, respectively) and HNSCC subjects (ORs 2.71-7.01 and 2.33-4.62, respectively). In conclusion our data showed that the C722T and the G135C polymorphisms of the XRCC3 and the RAD51 genes might be associated with HNSCC. Finally we suggested that these polymorphisms might be used as predictive factor of precancerous lesion for head and neck cancer in a Polish population.

MUTYH Tyr165Cys, OGG1 Ser326Cys and XPD Lys751Gln polymorphisms and head neck cancer susceptibility: a case control study.

In the present study we investigated the association between three polymorphisms of the MUTYH (Tyr165Cys, rs34612342), the OGG1 (Ser326Cys, rs1052133) and the XPD (Lys751Gln, rs13181) genes with head and neck cancer risk. Genotypes were determined in DNA from peripheral blood lymphocytes of 265 patients with head and neck squamous cell carcinoma (HNSCC) as well as 280 cancer-free controls by PCR-restriction fragment lenght polymorphisms. We found an association between HNSCC and the Ser326Cys (OR 1.69; 95% CI 1.19–2.45) as well as Cys326Cys (OR 4.56; 95% CI 2.07–10.05) variants of the OGG1 gene. The gene–gene interaction between MUTYH and OGG1 as well as OGG1 and XPD polymorphic variants may contribute to higher prevalence of HNSCC. We also found an association between Ser326Cys and Cys326Cys variants of OGG1 gene and smoking status in HNSCC patients (OR 1.97; 95% CI 1.25–3.11), (OR 3.54; 95% CI 1.39–9.04), respectively. Moreover, we also observed a protective association between Tyr165Cys variant of the MUTYH gene and non-smoking status in HNSCC (OR 0.34; 95% CI 0.17–0.66). We also found a link between gene–gene interaction (MUTYH and OGG1 or OGG1 and XPD) and smoking (ORs 2.17–4.20 and 2.18–5.23) or non-smoking status (ORs 0.11 and 7.61) in HNSCC patients, respectively. In conclusion our data showed that the Ser326Cys polymorphism of the OGG1 gene may modify the risk of HNSCC associated with smoking. Finally we suggested that this polymorphism might be used as predictive factor for head and neck cancer in Polish population.

Association between sorbitol dehydrogenase gene polymorphisms and type 2 diabetic retinopathy

Diabetic retinopathy (DR) may affect 98% of diabetic patients, but its aetiology is poorly understood. Besides glycaemic exposure, genetic factors likely contribute to the onset of DR. The polyol pathway, including aldose reductase and sorbitol dehydrogenase (SDH), can be activated under hyperglycaemic conditions. In our work we searched for an association between the C-1214G and G-888C polymorphisms of the SDH gene promoter and the occurrence and progression of type 2 DR. Two hundred and fifteen unrelated individuals with type 2 diabetes mellitus (T2DM) were divided into three groups: without DR, with non-proliferative diabetic retinopathy (NPDR) and with proliferative diabetic retinopathy (PDR). Genotypes of the C-1214G (rs2055858) and G-888C (rs3759890) polymorphisms of the SDH gene were determined with DNA from the peripheral blood lymphocytes of patients by restriction fragment length polymorphism and allele-specific PCR, respectively. The genotype distributions were contrasted by the chi(2) test and the significance of the polymorphism was assessed by multiple logistic regression producing odds ratios (ORs) and 95% confidence intervals (CIs). We found an association (OR 1.73, 95% CI 1.06-2.83) between NPDR and the G allele of the G-888C polymorphism. There was no association between NPDR and the other polymorphisms of the SDH gene. No differences were found in the distributions of these polymorphisms between patients with PDR and those with NPDR. A weak association (OR 2.0, 95% CI 1.29-3.07) was found between DR and the G allele of the G-888C polymorphism. Analysis of the combined genotypes (haplotypes) of both polymorphisms revealed associations between the C/G-C/G genotype and NPDR (OR 2.95, 95% CI 1.07-8.13) as well as DR in general (OR 2.91, 95% CI 1.15-7.36). The G-888C polymorphism of the SDH gene may be associated with the onset of DR rather than with its progression, and its effect may be strengthened by the interaction with the C-1214G polymorphism, but this association is rather weak and requires further study.

Reactive oxygen species promote localized DNA damage in glaucoma-iris tissues of elderly patients vulnerable to diabetic injury.

Glaucoma is typically an insidious-onset disease with serious visual consequences that has been positively linked to diabetes mellitus (DM). Glaucoma is more often present in the elderly. Important prognostic factors of glaucoma may be oxidative stress resulting from the toxic effects of glucose, and diabetes-associated vascular complications. Fifty-five patients and control subjects aged 71.0+/-10.1 yrs were enrolled in this study. Iris-tissue samples from DM type-2 patients, primary open-angle glaucoma-positive and -negative DM patients, and from healthy subjects were examined by use of the alkaline comet assay. We measured the DNA damage as numbers of strand breaks (SBs), oxidized purines as glycosyl-formamido-glycosylase (Fpg)-susceptible sites, and oxidized pyrimidines as endonuclease III (Nth)-susceptible sites. It was found that the level of oxidative damage in iris tissue was statistically higher in DM and glaucoma patients than that in healthy controls (oxidized purines: 38.0% and 34.7% vs 15.4%; oxidized pyrimidines: 43.3% and 39.0% vs 23.3%; P<0.001). Interestingly, we found strongly elevated levels of oxidized purines and pyrimidines in glaucomatous patients who also had DM, in comparison with healthy controls (oxidized purines: 55.7% vs 15.4%; oxidized pyrimidines: 61.8% vs 23.3%; P<0.001). Our observations suggest that the generation of reactive oxygen species may promote localized DNA damage in glaucoma-iris tissues of elderly patients vulnerable to diabetic injury.

Role of impaired DNA repair in genotoxic susceptibility of patients with head and neck cancer.

DNA repair is critical for genotoxic susceptibility and cancer development. Forty-seven patients with head and neck squamous cell carcinoma (HNSCC) and 38 healthy controls were enrolled in this study. Among the patients, 16 subjects had metastasis of HNSCC. The extent of DNA damage, including oxidative lesions, and efficiency of repair after genotoxic treatment with hydrogen peroxide were examined using the alkaline comet assay. HNSCC cells were sensitive to genotoxic treatment and displayed impaired DNA repair. In particular, lesions caused by hydrogen peroxide were repaired less effectively in cancer cells from patients with metastasis than in cells from healthy controls. We suggest that impaired DNA repair might play a role in genotoxic susceptibility of patients with head and neck cancer. Finally, as a consequence of this finding we have shown that treatment with DNA-reactive drugs could be considered as an effective therapy strategy for head and neck cancer.

Comparative study of DNA damage and repair in head and neck cancer after radiation treatment.

We compared DNA damage and the efficacy of its repair after genotoxic treatment with γ‐radiation of lymphocytes and tissue cells isolated from patients with squamous cell carcinoma of head and neck (HNSCC) and healthy donors. Thirty‐seven subjects with HNSCC and 35 healthy donors were enrolled in the study. The extent of DNA damage including oxidative lesions and efficiency of the repair were examined by alkaline comet assay. HNSCC cancer cells were more sensitive to genotoxic treatment and displayed impaired DNA repair. In particular, lesions caused by γ‐radiation were repaired less effectively in metastasis of HNSCC than in healthy controls. The differences in radiation sensitivity of cancer and control cells suggested that DNA repair might be critical for HNSCC treatment. We conclude that γ‐radiation might be considered as an effective therapeutic strategy for head and neck cancers, including patients in advanced stage of the disease with clear evidence of metastasis.