Abstract A33: Characterizing telomere and chromatin dynamics in colorectal cell transformation

Colon polyps are the most common neoplastic finding at colonoscopy and have the potential to transform to cancer. Understanding the mechanisms involved in the transformation from normal colon to polyp is central to the identification of interventions to prevent or stop a polyp from forming or, in the worst case, from transforming. Therefore, the clinical conundrum is to predict which polyps will progress. It is crucial to understand if there are molecular features that define premalignant lesions and that may contribute to the final steps of transformation, which could potentially be targets for early detection or more individualized clinical management. Cellular transformation is driven by the interplay of genetic and epigenetic changes, and a large body of research has identified modifications of chromatin and the role of those modifications in regulating genes. Telomeres, telomere maintenance mechanisms, and chromatin remodelers maintain genetic stability, and their disruption is associated with the development of many diseases, including cancer. Organoids are multicellular structures grown from the stem cells of an organ to recapitulate the diverse cell types of the parent organ. This renewable resource of an individual’s tissue provides the opportunity to study colon carcinogenesis in combination with advanced genomic tools such as gene editing. The overall objective of this study is to determine the role of telomere and chromatin remodeler alterations in neoplastic transformation. The functional interaction between hTERT and specific chromatin remodelers will be resolved in two steps: 1) activating telomerase in normal colon and polyp organoids from patients and measuring chromatin remodeler expression, and 2) incorporating mutations in the chromatin remodelers using genome editing and then measuring the expression of hTERT in the normal colon and polyp organoids from patients with cancer-adjacent and cancer-free polyps. Gene editing experiments were performed utilizing transposon-based vectors (PiggyBac), short homology arm-based knockin (GeneWeld), or CRISPR/Cas9, coupled with electroporation for cargo delivery. To assess neoplastic transformation as a result of the gene edits, we used histology and cellular morphology of the organoid specimen by hematoxylin and eosin staining and pathologist review, and the markers by immunofluorescence. These models of neoplastic transformation in organoids from patient tissues provide an accessible tool to visualize the functional changes that correspond to alterations in telomerase and chromatin remodelers and how alterations in these targets affect growth, proliferation, differentiation, and cell turnover. Identification of epigenomic molecular alterations linked with progression of polyps to cancer could lead to modifiable targets for preventive interventions and provide candidate molecular markers in order to better tailor polyp patient screening recommendations. Note: This abstract was not presented at the conference. Citation Format: Brooke R. Druliner, Brandon Simone, Miguel Munoz-Gomez, Kim Kossick, Daniel O9Brien, Alexej Abyzov, Stephen Ekker, Lisa A. Boardman. Characterizing telomere and chromatin dynamics in colorectal cell transformation [abstract]. In: Proceedings of the AACR Special Conference on the Evolving Landscape of Cancer Modeling; 2020 Mar 2-5; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2020;80(11 Suppl):Abstract nr A33.