Abstract 7005: Distinct DNA methylation patterns between early-onset and average-onset colorectal cancer patients
Authors: Su L. Joseph , Hsu Ping-Ching , Rathod Aniruddha , Liu Yulun , Ferruzzi Jacopo , Kazmi Syed , Huang Emina 
Published: March 2024

Abstract
Objective: Early onset colorectal cancer (EO CRC) is rising at an alarming rate. While average onset colorectal cancer (AO CRC) affects patients mostly above 65 years of age, EO CRC affects patients under 50 years of age, disproportionately affecting males from low-income communities and racial/ethnic minorities. Chronic inflammation has been identified as a strong contributor to pathogenesis. We hypothesize that methylation of DNA may serve as a potential mechanism associated with chronic inflammation that contributes to the etiology differentially between EO and AO CRC.
Methods: Formalin-fixed paraffin-embedded (FFPE) tissue specimens from four AO and EO CRC patients each were retrieved from the Tissue Repository. Paraffin curls containing tumor and adjacent normal tissues were generated from appropriate EO and AO CRC patient tissues. The Qiagen GeneRead DNA FFPE genomic DNA kit was then used to extract the DNA from the paraffin curls. Illumina Methylation EPIC v2.0 kit was used to evaluate DNA methylation (DNAm) patterns after the restoration process from deamination in the fixed/embedded sample using the Uracil-N-Glycosylase enzyme. Unreliable and non-specific probes were removed before statistical analysis for differentially methylated CpG sites. Age acceleration for each tissue was calculated by comparing the estimated DNAm age with chronological age using the Horvath approach.
Results: A clear clustering of DNAm patterns by age of onset were observed for both normal and tumor tissues. However, there was no difference when comparing tumor and normal tissues after multiple corrections. Four-way ANCOVA adjusting for race, gender, BMI, and tissue type suggested that age onset was the most significant factor. We also found that age acceleration in EO CRC tissue is greater than in AO CRC. After applying Bonferroni correction, significant differentially methylated regions (DMRs) were found in the promoter and the gene body of SNTB1, NFATC3, SLC25A24, RABGAP1L, WDSUB1, WWOX, SELB, SLC28A3, and PPP6R2 in EO CRC patients when compared to AO CRC. SNTB1 regulates colorectal cancer progression and stemness, while NFATC3 has been associated with inflammation and cancer.
Conclusions: The preliminary results from this study showed a significant difference in the DNAm profile of FFPE samples between AO and EO CRC. The finding suggests that epigenetics may play a role in the etiology of CRC, potentially involved in the chronic inflammation pathway. The analysis of a larger patient number is underway to strengthen these findings.
Citation Format: L. Joseph Su, Ping-Ching Hsu, Aniruddha Rathod, Yulun Liu, Jacopo Ferruzzi, Syed Kazmi, Emina Huang. Distinct DNA methylation patterns between early-onset and average-onset colorectal cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7005.