RESUMO
Sequential treatment of bisulfate-converted DNA was used to study methylation of promoter areas of SEPT9, HLTF, ALX4 and CDH1 genes. Methylation profiles were evaluated by comparing bioptical findings on colorectal cancer (n=55) and morphologically intact areas of the large bowel (n=71). Significant differences between groups were established for SEPT9, HLTF and ALX4 genes (p < or = 10(-9)) in evaluating medium-rate methylation of CpG. Diagnostic sensitivity (Se) peaked for SEPT9 (78 +/- 7%); specificity--(86 +/- 4%) (Sp). On site CpG (position "+14"), similar findings were reported: Se=81 +/- 6%, Sp=77 +/- 5%. Therefore, CpG(14)SEPT9 may be used as a separate marker. As a result of the use of HLTF as marker on all 23 sites, Se was 67 +/- 6% and Sp--87 +/- 3%; ALX4 diagnostic sensitivity--59 +/- 6%. Specificity level was similar to those of the other genes (88 +/- 3%). Despite the role of CDH1 gene in colorectal cancer, the group-to-group differences in methylation rates were minimal. Such values of Se and Sp as 54 +/- 6% and 67 +/- 5%, respectively, could not support methylation of the CDH1 promoter area for diagnostic purposes. Therefore, combined evaluation of SEPT9, HLTF and ALX4 genes offered more advantage as far as diagnosis is concerned. Hypermethylation in two of the three genes was assumed as a criterion for diagnosis. Under such conditions, diagnostic sensitivity was 81 +/- 7% (Sp=93 +/- 3%). With such high values, the criterion has a potential of being instrumental in working out diagnostic tests for colorectal cancer.
Assuntos
Biomarcadores Tumorais/genética , Caderinas/genética , Neoplasias Colorretais/diagnóstico , Proteínas do Citoesqueleto/genética , Metilação de DNA , Proteínas de Ligação a DNA/genética , Proteínas de Ligação ao GTP/genética , Fatores de Transcrição/genética , Adulto , Idoso , Antígenos CD , Neoplasias Colorretais/genética , Ilhas de CpG , Diagnóstico Diferencial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Sensibilidade e Especificidade , SeptinasRESUMO
High prevalence of colorectal cancer makes it a most serious socio-medical problem. Hence, the necessity of overall screening for prodromal changes and malignant neoplasms at the early stages of the disease. Despite a variety of efficacious instrumental diagnostic tools, the development of non-invasive screening techniques based on recent progress in understanding molecular mechanisms of carcinogenesis remains a highly topical issue. A pathogenetic model of colorectal cancer and pathophysiological basis of screening for colonic neoplasms are considered with the emphasis on the detection of tumour cells in faeces and their DNA carrying mutations in suppressor genes and oncogenes. Results of the studies with the use of one or several DNA oncomarkers are analysed in the context of their value for the diagnosis of colorectal neoplasms. High sensitivity and specificity of these methods make them very promising for application to the screening for colorectal cancer.
Assuntos
Neoplasias Colorretais/diagnóstico , Programas de Rastreamento/métodos , Biomarcadores Tumorais/análise , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Marcadores Genéticos , Humanos , Técnicas de Diagnóstico Molecular , Mutação , Lesões Pré-Cancerosas/diagnóstico , Lesões Pré-Cancerosas/patologia , Lesões Pré-Cancerosas/terapiaRESUMO
Polymorphisms of promotor region of IL-8, IL-10, and IL-12 genes were analyzed in cancer patients and subjects without history of cancer. The distribution of alleles of the analyzed polymorphisms in the control group coincided with that in other Caucasian populations. The incidences of three IL-10 gene polymorphisms (G-1082A, C-819T, and C-592A) significantly differed in controls and patients. Of 8 theoretically probable IL-10 gene haplotypes determined by these polymorphisms, 3 variants were revealed. Haplotype ACC was more incident in cancer patients, while ATA haplotype was rarer. The results are in line with the findings of other studies indicating the involvement of the immune system genes in the pathogenesis of cancer.
Assuntos
Predisposição Genética para Doença , Haplótipos , Interleucina-10/genética , Neoplasias , Polimorfismo Genético , Alelos , Humanos , Interleucina-12/genética , Interleucina-8/genética , Neoplasias/genética , Neoplasias/imunologia , Regiões Promotoras GenéticasRESUMO
The conformational models of the active site of adenosine deaminase (ADA) and its complexes in the basic state with adenosine and 13 isosteric analogues of the aza, deaza, and azadeaza series were constructed. The optimization of the conformational energy of the active site and the nucleoside bound with it in the complex was achieved in the force field of the whole enzyme (the 1ADD structure was used) within the molecular mechanics model using the AMBER 99 potentials. The stable conformational states of each of the complexes, as well as the optimal conformation of the ADA in the absence of ligand, were determined. It was proved that the conformational state that is close to the structure of the ADA complex with 1-deazaadenosine (1ADD) known from the X-ray study corresponds to one of the local minima of the potential surface. Another, a significantly deeper minimum was determined; it differs from the first minimum by the mutual orientation of side chains of amino acid residues. A similar conformational state is optimal for the ADA active site in the absence of the bound ligand. A qualitative correlation exists between the values of potential energies of the complexes in this conformation and the enzymatic activity of ADA toward the corresponding nucleosides. The dynamics of conformational conversions of the active site after the binding of substrate or its analogues, as well as the possibility of the estimation of the inhibitory properties of nucleosides on the basis of calculations, are discussed.