Standardization of TP53 gene mutations analysis on oral squamous cell carcinoma from paraffin-embedded tissues

Introduction:The tumor protein p53 gene (TP53) is a constant target of investigation in cancer pathogenesis. Analysis by immunohistochemistry provides limited data about p53 in oral carcinogenesis, and TP53sequencing can contribute to this analysis. However, obtaining high-quality and contamination-free deoxyribonucleic acid (DNA) for a proper amplification can be a difficult task when using paraffin-embedded tissues.Objective:Standardize DNA extraction, polymerase chain reaction (PCR) amplification and DNA sequencing techniques for TP53 mutation analysis.Material and methods:Thirty-nine cases of oral squamous cell carcinoma (OSCC) were selected from the Pathology Division of Instituto Nacional de Câncer (Inca). The DNA extraction method used was the QIAamp® DNA minikit® system. After DNA quantification by spectrophotometry, 250 ng of genetic material obtained from TP53 gene were amplified by PCR for exon 2 and by nested PCR for exon 6. Out of the total sample, 11 cases were selected for exon 2 sequencing. Results: The DNA samples presented mean concentration of 119.74 ± 88.86 ng/µl (28.9-556.4) and purity of 1.69 ± 0.18 (1-1.9). Thirty-three (84.6%) samples were amplified for exon 2, and all samples for exon 6 (39/100%). Readable sequencing data were obtained in 10 (90.9%) cases.Conclusion:Optimization of conditions for TP53 sequencing was obtained, and this will facilitate the analysis of mutations in paraffin-embedded tissues, allowing molecular retrospective studies.