Comparison of protocols for removal of melanin from genomic DNA to optimize PCR amplification of DNA purified from highly pigmented lesions

Autor(es)

Silva Almeida Vicentel, Anna Luiza ^[1] ; Bianchini, Raquel Alves ^[1] ; Laus, Ana Carolina ^[1] ; Macedo, Graziela ^[2] ; Reis, Rui Manuel ^{[3, 1, 4]} ; Vazquez, Vinicius de Lima ^{[1, 5]}

Afiliação do(s) autor(es)

^[1] Barretos Canc Hosp, Mol Oncol Res Ctr, Antenor Duarte Villela 1331, BR-14784400 Sao Paulo - Brazil

^[2] Barretos Canc Hosp, Dept Pathol, Sao Paulo - Brazil

^[3] Univ Minho, Sch Hlth Sci, Life & Hlth Sci Res Inst ICVS, Braga - Portugal

^[4] ICVS 63Bs PT Govt Associate Lab, Braga - Portugal

^[5] Barretos Canc Hosp, Dept Surg Melanoma Sarcoma, Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: HISTOLOGY AND HISTOPATHOLOGY; v. 34, n. 9, p. 1089-1096, SEP 2019.
• Citações Web of Science: 0

Resumo

Melanin is produced by melanocytes and protects against DNA damage by ultraviolet light. Unfortunately, the melanin protein present in melanoma tumor cells is often co-purified during DNA extraction, and this contamination may inhibit subsequent PCR methods, which directly impacts research applications and the molecular diagnostic tests needed for targeted therapeutics. There are presently no described purification protocols that efficiently remove melanin from genomic DNA. In this study, we compare six different methods for melanin removal from genomic DNA: Agarose Gel Electrophoresis, 1mg Chelex (R)-100, Chelex (R)-100 5%, centrifugation, OneStep (TM) PCR Inhibitor Removal Kit and centrifugation plus OneStep (TM) PCR Inhibitor Removal Kit. Each comparison was made using 16 formalin-fixed paraffin-embedded (FFPE) and 11 fresh cell line samples. All samples were initially tested using the multiplex PCR reaction for GAPDH gene that generates different sized amplified products: 100, 200, 300 and 400 base pairs, which could be inhibited by the addition of exogenous melanin. Six purification protocols were then applied, and all samples that amplified at least one GAPDH fragment were sequenced to analyze the presence of the BRAF V600E mutation. The efficiencies of amplification decreased for larger sized fragments in all methods. Our comparisons showed that centrifugation combined with the OneStep (TM) PCR Inhibitor Removal Kit was superior to all other methods for successful BRAF sequencing with 100% (100bp), 75% (200bp), 50% (300bp), and 31.3% (400bp) amplification efficiencies for the different amplicon sizes. In conclusion, this genomic DNA extraction method is highly efficient for successful PCR when tumor samples are contaminated with melanin. (AU)

• Processo FAPESP: 17/09612-0 - O Papel da Metilação na Iniciação e Progressão do Melanoma e o Impacto Epigenético in vitro
• Beneficiário: Anna Luiza Silva Almeida Vicente
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado
• Processo FAPESP: 12/04194-1 - Avaliação do papel biológico e clínico de alterações nas vias moleculares RAS-MAPK e PI3K-Akt , em melanomas cutâneos e de mucosa em população brasileira e comparação com a população estadunidense
• Beneficiário: Vinicius de Lima Vazquez
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 16/15941-3 - O Papel da Metilação na Iniciação e Progressão do Melanoma e o Impacto Epigenético in vitro.
• Beneficiário: Anna Luiza Silva Almeida Vicente
• Modalidade de apoio: Bolsas no Brasil - Doutorado