Estudo do Polimorfismo Genético dos Receptores de Vitamina D BsmI, ApaI e dos Genes CYP27B1 e CYP24A1 e sua relação com os níveis séricos da Vitamina D e a suscetibilidade ao Câncer Colorretal
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Data
2015-03-31
Autores
Vidigal, Veronica Marques [UNIFESP]
Orientadores
Forones, Nora Manoukian [UNIFESP]
Tipo
Tese de doutorado
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O câncer colorretal (CCR) é mundialmente, o terceiro mais comum entre homens e o segundo entre mulheres. Fatores genéticos, ambientais e doenças inflamatórias podem aumentar o risco de CCR, enquanto a Vitamina D é apontada como componente de efeito protetor juntamente com o cálcio. A principal via de produção desta vitamina ocorre com exposição da pele à luz solar, onde os precursores são transformados em pré-vitamina e transportados aos órgãos onde são convertidos em 25-OH Vitamina D (forma circulante) e posteriormente, em 1,25(OH)2 Vitamina D3 (forma ativa) pela CYP27B1. Ocorrendo metabolização pela CYP24A1, a Vitamina D ativa se liga ao seu receptor (VDR) e levada ao meio intracelular, liga-se a sequências específicas de DNA, onde polimorfismos dos VDR interferem na absorção intestinal de cálcio. Objetivos: Investigar a relação entre os polimorfismos dos VDR BsmI, ApaI e dos genes CYP27B1 e CYP24A1 aos níveis séricos da vitamina D, assim como o estilo de vida e hábitos alimentares ao risco de desenvolvimento de CCR. Métodos: Foram incluídos 152 pacientes com de CCR, e 321 indivíduos sem câncer (grupo controle). Todos os indivíduos foram submetidos a um questionário sobre hábitos alimentares, etilismo e tabagismo, análise de prontuário e a coleta de sangue periférico para extração do DNA genômico e avaliação do nível sérico de Vitamina D por HPLC. Os polimorfismos estudados foram investigados pela a técnica de PCR e a genotipagem por RFLP e sequenciamento genético. O teste Exato de Fisher, T-Student, ANOVA, correlação de Pearson, sobrevida pelas curvas de Kaplan-Meier e teste de Log-Rank foram realizados para obtenção dos resultados, assim como as análises uni, mutlivariadas e ponderadas. Os valores de p <0,05 foram considerados estatisticamente significantes. Resultados: A média de idade nos grupos foi de 62,8 anos. O baixo ou nulo consumo de frutas, cereais, leite e derivados, bem como o tabagismo e etilismo foram associados a maior risco de CCR. A sazonalidade alterou as médias dos níveis séricos de Vitamina D circulante e quando realizada análise estatística ponderada, os indivíduos com status de deficiência, tiveram maior risco de CCR. Não houve associação entre sobrevida e as variantes genéticas estudadas e as dosagens dos níveis séricos de Vitamina D. Em ApaI, o genótipo heterozigoto Aa ou a associação aa+Aa aumentou o risco de CCR; porém para BsmI, os resultados não foram estatisticamente significantes. Após análise multivariada, foram associados a maior risco de CCR o heterozigoto e a associação AT+AA do rs6013897; os genótipos CT e CC do rs158552 e a associação CT+CC de CYP24A1 e para CYP27B1, o heterozigoto GT e a associação GT+TT do rs10877012. Conclusões: Foram associados ao risco de CCR, fatores ambientais como hábitos alimentares e estilo de vida, alguns dos polimorfismos (VDR ApaI, SNPs rs6013897, rs158552 e rs10877012) estudados e o perfil de deficiência de Vitamina D circulante. Não foram associadas à sobrevida as dosagens da Vitamina D e as variantes genéticas. As médias dos níveis séricos da Vitamina D e o risco de CCR sofreram interferências externas e intrínsecas, prejudicando a síntese e metabolismo desta vitamina.
Worldwide, colorectal cancer (CRC) is the third most common cancer among men and the second among women. Genetic, environmental and inflammatory diseases may increase the risk of CRC, while vitamin D is indicated as protective effect of component along with calcium. The major source of production of this vitamin occurs with exposing the skin to sunlight, where the precursors are transformed into pre-vitamin and transported to the organs where they are converted to 25-OH Vitamin D (current form) and later, at 1.25 (OH) 2 vitamin D3 (active form) by CYP27B1. After metabolized by CYP24A1, the active vitamin D binds to its receptor (VDR) and loaded to the intracellular and binds to specific sequences of DNA, where the polymorphism of VDR interfere with intestinal absorption of calcium. Objectives: To investigate the relationship between polymorphisms of VDR BsmI, ApaI and CYP27B1 and CYP24A1 genes to serum vitamin D levels, as well as the lifestyle and eating habits to the risk of CRC development. Methods: We included 152 patients with CRC, and 321 subjects without cancer (control group). All subjects answered a questionnaire to investigate eating habits, alcoholism and smoke. Medical record were analyzed and peripheral blood were collected for genomic DNA extraction and assessment of serum levels of Vitamin D by HPLC. Polymorphisms were studied by PCR and genotyping by RFLP and genetic sequencing. Fisher's exact test, t-Student, ANOVA, Pearson correlation, survival by Kaplan-Meier and log-rank tests were performed to analyze the results, as well as univariate, mutlivariate and weighted. P values <0.05 were considered statistically significant. Results: The mean age of groups was 62.8 years. The low or no consumption of fruits, cereals, dairy products, as well as smoking and alcohol consumption were associated with increased risk of CRC. Seasonality changed the mean serum levels of vitamin D circulating and when performed the weighted statistical analysis, individuals with deficient status, had a higher risk of CRC. There was no association between survival the genetic variants studied and the levels of serum levels of vitamin D. The heterozygous genotype Aa or association aa+Aa of ApaI increased the risk of CRC. For BsmI, the results were not statistically significant. After multivariate analysis, the heterozygous and the association AT+AA of rs6013897; CT and CC genotypes of rs158552 and the association of CT+CC of CYP24A1 and the heterozygous GT and GT+TT of CYP27B1 of rs10877012 were related to higher risk of CRC. Conclusions: Environmental factors such dietary habits and lifestyle, some polymorphisms studied (VDR ApaI, SNPs rs6013897, rs158552 and rs10877012) and the current Vitamin D deficiency were associated to a higher risk of CRC. Vitamin D and the genetic variants were not with survival. Therefore, the mean serum levels of vitamin D and the risk of CRC suffered external and intrinsic interference, impairing its synthesis and metabolism of this vitamin.
Worldwide, colorectal cancer (CRC) is the third most common cancer among men and the second among women. Genetic, environmental and inflammatory diseases may increase the risk of CRC, while vitamin D is indicated as protective effect of component along with calcium. The major source of production of this vitamin occurs with exposing the skin to sunlight, where the precursors are transformed into pre-vitamin and transported to the organs where they are converted to 25-OH Vitamin D (current form) and later, at 1.25 (OH) 2 vitamin D3 (active form) by CYP27B1. After metabolized by CYP24A1, the active vitamin D binds to its receptor (VDR) and loaded to the intracellular and binds to specific sequences of DNA, where the polymorphism of VDR interfere with intestinal absorption of calcium. Objectives: To investigate the relationship between polymorphisms of VDR BsmI, ApaI and CYP27B1 and CYP24A1 genes to serum vitamin D levels, as well as the lifestyle and eating habits to the risk of CRC development. Methods: We included 152 patients with CRC, and 321 subjects without cancer (control group). All subjects answered a questionnaire to investigate eating habits, alcoholism and smoke. Medical record were analyzed and peripheral blood were collected for genomic DNA extraction and assessment of serum levels of Vitamin D by HPLC. Polymorphisms were studied by PCR and genotyping by RFLP and genetic sequencing. Fisher's exact test, t-Student, ANOVA, Pearson correlation, survival by Kaplan-Meier and log-rank tests were performed to analyze the results, as well as univariate, mutlivariate and weighted. P values <0.05 were considered statistically significant. Results: The mean age of groups was 62.8 years. The low or no consumption of fruits, cereals, dairy products, as well as smoking and alcohol consumption were associated with increased risk of CRC. Seasonality changed the mean serum levels of vitamin D circulating and when performed the weighted statistical analysis, individuals with deficient status, had a higher risk of CRC. There was no association between survival the genetic variants studied and the levels of serum levels of vitamin D. The heterozygous genotype Aa or association aa+Aa of ApaI increased the risk of CRC. For BsmI, the results were not statistically significant. After multivariate analysis, the heterozygous and the association AT+AA of rs6013897; CT and CC genotypes of rs158552 and the association of CT+CC of CYP24A1 and the heterozygous GT and GT+TT of CYP27B1 of rs10877012 were related to higher risk of CRC. Conclusions: Environmental factors such dietary habits and lifestyle, some polymorphisms studied (VDR ApaI, SNPs rs6013897, rs158552 and rs10877012) and the current Vitamin D deficiency were associated to a higher risk of CRC. Vitamin D and the genetic variants were not with survival. Therefore, the mean serum levels of vitamin D and the risk of CRC suffered external and intrinsic interference, impairing its synthesis and metabolism of this vitamin.
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VIDIGAL, Veronica Marques. Estudo do Polimorfismo Genético dos Receptores de Vitamina D BsmI, ApaI e dos Genes CYP27B1 e CYP24A1 e sua relação com os níveis séricos da Vitamina D e a suscetibilidade ao Câncer Colorretal. 2015. Tese (Doutorado) - Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, 2015.