Abstract

HERRERA, JehisonA. et al. Evaluation of DNA methylation in formalin-fixed, paraffin embedded colorectal cancer tissues (FFPE). rev.colomb.cancerol. [online]. 2021, vol.25, n.2, pp.110-114.  Epub May 06, 2022. ISSN 0123-9015.  https://doi.org/10.35509/01239015.704.

Alterations in the methylation of CpG dinucleotides in promoter regions is one of the epigenetic mechanisms involved in cancer that has potential use as a biomarker. Its evaluation from formalin-fixed and paraffin-embedded (FFPE) tissues represents a great challenge given the partial degradation, crosslinking, and low amounts of the obtained DNA. In this technical note we describe a protocol for the study of the methylation status of the distal promoter of the K-RAS proto-oncogene from several samples obtained from two 11-years old FFPE tissues of colorectal cancer. An alternative bisulfite conversion protocol to the usual one was used; a modified DNA polymerase and a nested PCR were used and the direct sequencing of the converted DNA with bisulfite was optimized. This protocol could be applied to determine methylation states in other genes and types of cancer.

Keywords : DNA Methylation; 5-Methylcytosine; Genes ras; Colorectal Neoplasms; Paraffin-embedded tissue.

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