Estudo do polimorfismo no códon 72 do gene TP53 na Leucemia Mielóide Crônica e associação com possível resposta ao tratamento com imatinibe

• Autor(a) principal: Santos, Jeany Camelo
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• dARK ID: ark:/38995/0013000005mbj
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/3358
• topic: Leucemia mielóide crônica; Códon 72; TP53; Polimorfismo; Imatinibe; Chronic mieloyd leukemia; Codon 72; Polymorphisms; Imatinib; BIOQUIMICA::BIOLOGIA MOLECULAR

The CML is a expansion clonal of cells progenitors hematopoietics and is associated to an specific genetic lesion, known as the Philadelphia chromosome, product of the reciprocal translocation t(9, 22)(q34, q11) that causes the oncogene BCR-ABL. The TP53 is a tumor suppressor gene located on the chromossome 17p13.1 coding for phosphoprotein TP53. The polymorphism arises from the exchange of G for C at codon 72, resulting the genotypes Arg/Arg, Arg/Pro and Pro/Pro. This study aims to determine the allelic and genotypic frequencies of TP53 polymorphism at codon 72 in CML patients and to correlate with the response to imatinib therapy. The work had the participation of 85 CML patients treated at the Clinic of Hematology, at Hospital das Clínicas – UFG in Goiânia city, state of Goiás for the diagnosis and control of disease. To investigate the allelic and genotypic frequencies, DNA samples were isolated from peripheral blood for analysis of PCR reactions. For genotyping, forward and reverse primers were used for each variant allelic. The study had the participation of 85 CML patients, which 69 were in chronic phase, eight in accelerated phase and only one in blast crisis. The mean age was 51 years and eight months. The frequency of genotypes Pro/Pro, Arg/Pro and Arg/Arg was 11% (4/35) 43% (15/35) 46% (16/35) for patients resistant to imatinib treatment (group case) and 16% (8/50) 62% (31/50) and 22% (11/30) for patients with response to imatinib (control group), respectively. The population in this study is in Hardy-Weinberg Equilibrium (x2 = 1, 12, P> 0, 05). Regarding age, gender, disease stage, and score Sokal not observed an association of the disease with the response or resistance to treatment (P= 0,36; P = 0.82, P = 0.47 and P = 0.72), respectively. When we evaluated the genotypes with respect to the Score Sokal (High x Intermediate/Low), it was observed that Pro/Pro genotype was significantly lower in the high Sokal Score group than Intermediate/low (P = 0.017, OR = 8, 19). For criterion, age over 40 years old at diagnosis, by analyzing the Fisher’s test, we found that patients carrying the Arg/Arg genotype are four times more susceptible to produce any resistance to imatinib therapy. When we evaluated the variables age, gender, disease phase, genotype and Sokal Score in logistic regression showed that only the variable genotype was significant (P = 0.0159). Our results are not according to the previous studies, in which suggest that the Pro/Pro genotype and the Pro allele can check risk of developing disease or resistance to imatinib treatment. Our findings suggest that patients carrying the Arg/Pro and Pro/Pro genotypes responded well to treatment and that the Pro/Pro genotype represented an indicator for a good prognosis. Genotype Arg/Arg represented a risk factor in genetic susceptibility in CML’s pathogenesis, contributing for a worse outcome.