Avaliação de dois métodos de extração de DNA de material parafinado para amplificação em PCR
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Data
2007-04-01
Autores
Simonato, Luciana Estevam [UNESP]
Garcia, José Fernando [UNESP]
Nunes, Caris Maroni [UNESP]
Miyahara, Glauco Issamu [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Patologia ClínicaSociedade Brasileira de PatologiaSociedade Brasileira de Citopatologia
Resumo
INTRODUÇÃO: Diversos métodos para extração de DNA a partir de tecidos biológicos inclusos em parafina encontram-se descritos na literatura, sendo o sucesso desse procedimento de grande importância para a realização de métodos moleculares de diagnóstico empregando a reação em cadeia da polimerase (PCR). OBJETIVO: Este estudo avaliou dois métodos de extração de DNA de material parafinado, visando à amplificação do DNA genômico pela técnica da PCR. MATERIAL E MÉTODO: Foram utilizadas 35 amostras de casos de carcinoma epidermóide de assoalho bucal diagnosticados e tratados no Centro de Oncologia Bucal da Universidade Estadual Paulista (Unesp). Os métodos de extração de DNA avaliados incluíram: 1. digestão com proteinase K seguida por purificação com Chelex 100® (BioRad); e 2. sistema QIAamp DNA minikit® (Qiagen). O DNA obtido foi quantificado por espectrofotometria e amplificado pela técnica da PCR, utilizando-se oligonucleotídeos iniciadores para betaglobina. RESULTADOS: A concentração de DNA obtido do material extraído com o primeiro método apresentou média de 120,62 ng/µl com razão entre as leituras das absorbâncias 260/280 variando de 0,8 a 1,41. Para as amostras extraídas com o segundo procedimento, o rendimento médio foi de 67,38 ng/µl, no entanto a razão 260/280 variou entre 1,11 e 2,53. O material foi submetido à PCR e, das 35 amostras extraídas com cada método, respectivamente, 29 e 30 apresentaram sinal positivo. CONCLUSÃO: Os dois métodos utilizados para obtenção de DNA de material parafinado apresentaram desempenho semelhante, revelando que ambos têm potencial para auxiliar na prática da biologia molecular diagnóstica, assim como no estudo diagnóstico retrospectivo em material parafinizado.
BACKGROUND: There are several methods for DNA extraction from formalin-fixed paraffin-embedded tissues reported in the literature. High success rate on this procedure is important for the use of molecular diagnostic methods based on the polymerase chain reaction (PCR). OBJECTIVE: Two methods of DNA extraction from paraffin-embedded samples were tested aiming at PCR amplification of genomic DNA. MATERIAL and METHOD: Thirty-five samples were obtained from patients with squamous cell carcinoma of mouth floor treated at the Oral Oncology Center in Universidade Estadual Paulista. The DNA extraction methods included: 1. proteinase K digestion followed by Chelex 100® (BioRad) purification and 2. QIAamp DNA minikit® system (Qiagen). Purified DNA was quantified by spectrophometry and a beta-globin gene fragment was amplified using PCR. RESULTS: The DNA concentration from samples applied to the first method presented an average of 120.62 ng/µl and absorbance ratio 260/280 varying between 0.8 and 1.41. From the samples extracted using the second procedure, the mean DNA concentration was 67.38 ng/µl, with absorbance ratio varying between 1.11 and 2.53. DNA samples were submitted to PCR and from 35 samples extracted with both methods, respectively, 29 and 30 were successfully amplified for the beta-globin gene. CONCLUSION: Both methods used to obtain genomic DNA from formalin-fixed paraffin-embedded tissues presented similar performance, revealing their potential to be included in diagnosis of molecular biology, as well as in retrospective studies using archived paraffin-embedded samples.
BACKGROUND: There are several methods for DNA extraction from formalin-fixed paraffin-embedded tissues reported in the literature. High success rate on this procedure is important for the use of molecular diagnostic methods based on the polymerase chain reaction (PCR). OBJECTIVE: Two methods of DNA extraction from paraffin-embedded samples were tested aiming at PCR amplification of genomic DNA. MATERIAL and METHOD: Thirty-five samples were obtained from patients with squamous cell carcinoma of mouth floor treated at the Oral Oncology Center in Universidade Estadual Paulista. The DNA extraction methods included: 1. proteinase K digestion followed by Chelex 100® (BioRad) purification and 2. QIAamp DNA minikit® system (Qiagen). Purified DNA was quantified by spectrophometry and a beta-globin gene fragment was amplified using PCR. RESULTS: The DNA concentration from samples applied to the first method presented an average of 120.62 ng/µl and absorbance ratio 260/280 varying between 0.8 and 1.41. From the samples extracted using the second procedure, the mean DNA concentration was 67.38 ng/µl, with absorbance ratio varying between 1.11 and 2.53. DNA samples were submitted to PCR and from 35 samples extracted with both methods, respectively, 29 and 30 were successfully amplified for the beta-globin gene. CONCLUSION: Both methods used to obtain genomic DNA from formalin-fixed paraffin-embedded tissues presented similar performance, revealing their potential to be included in diagnosis of molecular biology, as well as in retrospective studies using archived paraffin-embedded samples.
Descrição
Palavras-chave
DNA, Reação em cadeia da polimerase, Tecido parafinado, DNA, Polymerase chain reaction, Paraffin-embedded tissue
Como citar
Jornal Brasileiro de Patologia e Medicina Laboratorial. Sociedade Brasileira de Patologia ClínicaSociedade Brasileira de PatologiaSociedade Brasileira de Citopatologia, v. 43, n. 2, p. 121-127, 2007.