Abstract 4254: Genetically engineered human lung organoid models for lung cancer evolution study

Abstract Initial cellular events in a transitional period from normal to cancer cells, such as transcriptomic or epigenetic dynamics, are poorly understood. Observing these is more challenging than in cancer progression, especially for humans. Mapping this phenomenon in early cancer evolution is crucial, as we can identify targetable molecules to inhibit cancer development at the precancerous stage. Immortalized human cancer cell lines hardly capture these appropriately as they have lost usual cellular characteristics. Normal organoids harbor stem cells and their differentiated cells, reflecting the epithelial physiology of tissues, and are more suitable models for cancer evolution studies. To establish a human cancer development model in vitro, we genetically engineered normal human airway organoids derived from adult stem cells into small cell lung cancer (SCLC). We used CRISPR-Cas9 systems to induce non-homologous end-joining in both TP53 and RB1, the most frequently mutated genes of SCLC. First, we knocked out TP53 of the airway organoids, selected by Nutlin-3a, an MDM2 antagonist, for 3-4 weeks, demonstrating 88-89% editing efficiencies calculated from Sanger sequencing results. Most mutations were one base pair deletion or insertion, which induced frameshift mutation in TP53. They did not show a significant difference from wild-type organoids morphologically at bright-field microscopy. Subsequently, we targeted RB1 on TP53-/- airway organoids to induce SCLC. We used Palbociclib, a CDK4/6 inhibitor, to enrich the mutated cells. They had 67.1% efficiency, and 20.4% had a 7-base pair deletion mutation. In the initial period, they seemed to have similar shapes to TP53-/- organoids. Unexpectedly and interestingly, however, we noticed more rapidly proliferating and disorganized organoids disrupting their original round shapes appeared in 4-5 weeks. The cells were indiscriminately piled up on the airway organoids' apical and basolateral surfaces, indicating their malignant traits. Their chaotic proliferation represented the rapidly progressing clinical feature of SCLC with a median survival of 7-16 months with treatment. This is the first work constructing the SCLC development model from the normal human airway organoid. By sequentially single-cell sequencing this organoid model changing to tumorous condition, we can capture the multi-omics landscape during the initial evolution of SCLC. Citation Format: Sungji Moon, Rokhyun Kim, Dakyung Lee, Kyunghyuk Park, Woochan Lee, Seyoon Lee, Young Jun Park, Jongil Kim. Genetically engineered human lung organoid models for lung cancer evolution study [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 4254.