Efficiency of Base Excision Repair of Oxidative DNA Damage and Its Impact on the Risk of Colorectal Cancer in the Polish Population.

DNA oxidative lesions are widely considered as a potential risk factor for colorectal cancer development. The aim of this work was to determine the role of the efficiency of base excision repair, both in lymphocytes and in epithelial tissue, in patients with CRC and healthy subjects. SNPs were identified within genes responsible for steps following glycosylase action in BER, and patients and healthy subjects were genotyped. A radioisotopic BER assay was used for assessing repair efficiency and TaqMan for genotyping. Decreased BER activity was observed in lymphocyte extract from CRC patients and in cancer tissue extract, compared to healthy subjects. In addition, polymorphisms of EXO1, LIG3, and PolB may modulate the risk of colorectal cancer by decreasing (PolB) or increasing (LIG3 and EXO1) the chance of malignant transformation.

DNA double strand breaks repair and apoptosis induction in peripheral blood lymphocytes of head and neck cancer patients.

AIM: To evaluate the generation and repair of DNA double strand breaks (DSBs) as a critical factors that define the efficiency of radiation therapy of cancer patients. METHODS: Peripheral blood lymphocytes obtained from 18 patients with head and neck squamous cell carcinoma (HNSCC) and 18 healthy donors were studied. The efficiency of DSBs repair after genotoxic treatment with hydrogen peroxide and gamma-radiation were examined by neutral comet assay. MTT assay was used for cell viability analysis and Annexin V-FITC kit specific for kinase-3 was employed to determine apoptosis. RESULTS: Lymphocytes from HNSCC patients were sensitive to genotoxic treatment and displayed impaired DSBs repair. Finally, as a consequence of this finding we have evidenced higher rate of apoptosis induction after gamma-radiation treatment of lymphocytes from HNSCC patients than those from healthy controls. CONCLUSIONS: DSBs repair and increased apoptosis in cells of patients with head and neck cancer is relevant for efficient therapy of HNSCC.

The T/G mutation in exon 8 of hMSH2 gene in the sporadic colon cancer patients.

The DNA mismatch repair (MMR) system guards against genomic instability, therefore the mutations in the human MMR genes cause the majority of the hereditary nonpolyposis colorectal cancer (HNPCC) and a small percentage of the sporadic colon cancer. hMSH2 is one of MMR genes involved in the correction of mispairing during replication and its mutations are associated with both--microsatellite instability and the hereditary and sporadic colon tumourgenesis. The aim of this study was to analyse the T/G mutation (codon 458) in exon 8 of hMSH2 gene in the sporadic colon cancer cells. We also examined the relationship between the T/G mutation of hMSH2 gene, and the selected prognostic factors such as Dukes' stage, histological grade and lymph node metastasis. We analysed samples of tumour from 75 patients with sporadic colorectal cancers. The mutation in the hMSH2 gene ware determined by the RFLP-PCR. We found T/G mutation in exon 8 of hMSH2 gene in 5 patients (6,7%). There was no statistically significant difference between this mutation and selected clinical parameters. The results of our studies revealed that mutations of hMSH2 gene may lead to development of colorectal cancer. No dependence between the mutation of hMSH2 gene and clinical parameters, suggests that the mutation of hMSH2 gene may have a critical significance for the first steps of carcinogenesis in colon epithelial.

The Trp64Arg beta3-adrenergic receptor amino-acid variant is not associated with overweight and type 2 diabetes mellitus in Polish population.

The Trp64Arg amino-acid variant of the beta3 adrenoreceptor gene may be associated with a genetic predisposition to human obesity and related disorders, including type 2 diabetes mellitus. This relationship has been reported in various ethnic groups, however it was not extensively studied in Polish population. Therefore, the aim of the study was to investigate the association of Trp64Arg polymorphism of the beta3 adrenergic receptor gene with overweight and type 2 diabetes mellitus in polish subjects. The Trp64Arg polymorphism was determined by PCR-based MspI restriction fragment length polymorphism (PCR-RFLP). The study population consisted of 358 subjects, among whom 200 were diagnosed as overweight (BMI > 27 kg/m (2)). Among overweight subjects 111 presented with type 2 diabetes mellitus and 89 with normal glucose metabolism. All study participants were unrelated Caucasians and inhabited the city of Lodz, Poland. The frequency of the Arg allele did not differ significantly between overweight and normal weight patients (13 % vs. 11 %, OR 1.17, CI 0.74 - 1.85). The same applied to overweight diabetic patients vs. overweight patients without diabetes mellitus (13 % vs. 13 %, OR 0.97, CI 0.54 - 1.76). The obtained results suggest no association between Trp64Arg polymorphism of the beta3-AR gene and the incidence of overweight and type 2 diabetes mellitus in Polish population.

Distribution of C-->T and T-->C polymorphisms of the urokinase-type plasminogen activator gene in children with type 1 diabetes mellitus and insulin resistance.

We analysed the distribution of genotypes and frequency of alleles of two polymorphisms in the urokinase-type plasminogen activator (uPA) gene: a C-->T substitution in exon 6 and a T-->C substitution in intron 7 in 89 children with type 1 diabetes mellitus and insulin resistance compared with 120 non-diabetic control subjects. All genotypes were determined by the allele-specific polymerase chain reaction. We found that the frequency of the T/T homozygote (15%) in the patient group was significantly (P<0.05) higher than in the controls (7%). There were no differences in the distribution of the T-->C polymorphism between patients and controls, which suggests that this genetic change is probably phenotypically silent. In conclusion, our results indicate that the higher percentage of T/T homozygotes in patients might be associated with T1DM coexisting with insulin resistance.

An association between the matrix metalloproteinase 1 promoter gene polymorphism and lymphnode metastasis in breast cancer.

A single guanine insertion (1G/2G polymorphism) in the promoter of the matrix metalloproteinase (MMP-1) gene creates a binding site for the transcription factor and may affect the level of transcription of MMP-1. An elevated level of MMP-1 in cancer cells may facilitate their invasion and contribute to metastasis. To evaluate the contribution of 1G/2G polymorphism in the development and/or progression of breast cancer we genotyped 135 subjects with breast cancer. The 1G/2G polymorphism was determined by the method based on restriction endonuclease digestion. We found that the frequency of the 2G allele was higher in lymphnode-metastasis patients than in the group without metastasis (p < 0.001). We did not find differences between distribution of the genotypes and frequencies of alleles in cancer patients and in healthy subjects served as control. Our results suggest that allele 2G may be associated with lymphnode metastasis in patients with breast cancer and therefore it can be considered as a prognostic marker in this disease.

An association between the Trp64Arg polymorphism in the beta3-adrenergic receptor gene and endometrial cancer and obesity.

Beta3-adrenergic receptor (beta3AR) stimulates lipolysis in human fat cells, so its gene can constitute a candidate to explain a part of genetic predisposition to human obesity and related disorders. The Trp64Arg polymorphism in the beta3AR gene has been reported to be associated with insulin resistance, obesity and type 2 diabetes; little is known about its possible association with cancer. To check this association we determined the distribution of its genotypes and frequency of alleles in endometrial cancer patients with or without overweight/obesity as compared to appropriate controls. The Trp64Arg polymorphism was determined by PCR-based MspI restriction fragment length polymorphism in DNA of peripheral blood leukocytes. The study population consisted of 169 subjects, among them were 79 endometrial cancer patients and 90 controls without cancer. There were 34 obese (BMI > or = 30 kg/m2) and 22 overweight (30 BMI > or = BMI > or = 27 kg/m2) individuals among endometrial cancer patients. There was a significant (p < 0.001) difference in genotype distribution and allele frequency between endometrial cancer patients and controls without cancer. The odds ratios for the Trp/Arg and Arg/Arg genotypes as well as for the Arg allele were considerably higher than 1. Analysis of the polymorphism in the cancer group patients due to BMI revealed that the distribution of genotypes and the frequency of alleles in obese/overweight patients differed significantly from those in patients with normal weight with an odds ratio for the Trp/Arg genotype and the Arg allele of about 4. The prevalence of the Arg allele of the Trp64Arg polymorphism in the beta3-adrenergic receptor gene may contribute to the susceptibility to endometrial cancer among obese/overweight individuals.

Antigen levels of the urokinase-type plasminogen activator and its gene polymorphisms in colorectal cancer.

We analysed the distribution of genotypes of two polymorphisms in the urokinase-type plasminogen activator (uPA) gene: C-->T substitution in exon 6 and T-->C substitution in intron 7 in 52 subjects with colorectal cancer. Genotypes were determined in tumour tissue and distant mucosa samples by allele-specific polymerase chain reaction. The antigen levels of uPA in cancer tissue were higher than in distant mucosa as measured by enzyme-linked immunosorbent assay. The level of uPA antigens in cancer samples with the C/C genotype of C-->T polymorphism in exon 6 was higher than in samples with C/T and T/T genotypes. No differences in the level of uPA antigens between the alleles of the intron 7 T-->C polymorphism were found. As uPA can be involved in cancer invasion and metastasis, C/C genotype in exon 6 of uPA gene can be further considered as being related to colorectal cancer progression.

A C/T polymorphism in the urokinase-type plasminogen activator gene in colorectal cancer.

Urokinase plasminogen activation system can play an important role in the appearance and progression of many cancers. Urokinase-type plasminogen activator (uPA) is implicated in the control of cell adhesion and invasion, and is regarded as a strong prognostic marker in colorectal cancer. A C-->T substitution (the C/T polymorphism) in the nucleotide sequence encoding the kringle structure of uPA results in an alteration from proline to leucine at position 121. This substitution may be directly or indirectly involved in the decreased affinity for uPA substrates. In the present work the distribution of genotypes and frequencies of alleles of the C/T polymorphism were investigated. Tumour tissues and distal mucosa samples were obtained from 40 patients with colorectal cancer. Blood samples from sex and age matched healthy individuals served as control. The C/T polymorphism was determined by PCR amplification using the allele specific primers. No differences between genotypes of the C/T polymorphism in cancer tissue and distant mucosa of each patient were found. The distributions of the genotypes in both patients and control differed significantly (p < 0.05) from that predicted by the Hardy-Weinberg distribution. A distinct preference of heterozygotes (70% - patients, 65% - controls) was observed in both patients and controls. Additionally, there were no differences in the frequencies of the C and T alleles in both groups. The C/T polymorphism of the uPA gene may not be linked with colorectal cancer.