Abstract PO-019: DNA methylation status in a promoter region of the K-RAS gene in patients with Colorectal Cancer

Background: DNA methylation plays an important role in colorectal cancer (CRC) carcinogenesis. The mutated K-RAS gene has been reported to be crucial in CRC progression, but it is not known whether the wild-type gene is regulated by methylation and whether or not this mechanism contributes to disease progression. Now, there are not known reports about the methylation status of the distal K-RAS gene promoter in patients diagnosed with CRC. Materials and methods: Fifty-seven formalin-fixed, paraffin-embedded (FFPE) tissue samples from 57 patients diagnosed with CRC, without K-RAS mutation, were analyzed to determine the methylation status of the distal promoter of this gene. The analysis was performed by DNA extraction from laser microdissections, and 2 mm diameter punch, conversion with sodium bisulfite, amplification by nested PCR, and direct sequencing of purified PCR products. Results: Of the 57 cases, in 2 (6.25%) partial methylation was found in island 2 for one of the cases and in islands 1 and 2 for the other. In 30 (93.75%) cases no methylation was found and in the remaining 25 (43.85%) cases methylation could not be determined, probably due to the quantity and quality of DNA extracted from these blocks. Conclusion: The results found from the preliminary analysis of the methylation status of a region of the distal promoter of the K-RAS gene that serves as an anchorage to Sp1, allowed to determine a partial methylation status in 6.25% of the cases studied, concluding that methylation in this region is not a frequent event Citation Format: Jehison Alirio Herrera-Pulido, Orlando Ricaurte-Guerrero, Jinneth Acosta-Forero, Pablo Moreno-Acosta, Maria Carolina Sanabria-Salas, Humberto Arboleda-Granados, Gustavo Hernandez, Martha Lucia Serrano-Lopez. DNA methylation status in a promoter region of the K-RAS gene in patients with Colorectal Cancer [abstract]. In: Abstracts: AACR Special Virtual Conference on Epigenetics and Metabolism; October 15-16, 2020; 2020 Oct 15-16. Philadelphia (PA): AACR; Cancer Res 2020;80(23 Suppl):Abstract nr PO-019.