Abstract PR11: Investigating lung cancer cells-of-origin using three-dimensional organoid cultures

Abstract

Abstract There are many distinct epithelial cell types in the adult lung that could give rise to non-small cell lung cancer. These cell types include tracheal basal stem cells, tracheal club cells, distal lung bronchioalveolar stem cells (BASCs), and distal lung alveolar type 2 cells (AT2). My laboratory is using mouse models to test directly which lung stem and progenitor cells are most fit to serve as cells-of-origin of lung adenocarcinoma and lung squamous cell carcinoma. Previously, we demonstrated that tracheal club cells and BASCs are the likely cells-of-origin for KRASG12D; Lkb1-null adenosquamous tumors. The same strategy is now being used to test which cells can give rise to adenocarcinomas using the LSL:EGFRT90M/L858R (LSL=lox-stop-lox) mouse strain, or squamous cell carcinoma using the Lkb1flox/flox; Ptenflox/flox mouse strain. Briefly, tracheas and lungs from Cre-naïve mice are enzymatically dissociated, and fluorescence activated cell sorting (FACS) is used to enrich for four distinct populations: NGFR+/Sca1+ tracheal basal cells, NGFR-/Sca1+ tracheal club cells, Sca1+ distal lung BASCs, and Sca1- distal lung AT2 cells. Each population is then incubated with either adeno-GFP control virus or adeno-Cre virus to induce EGFR T790M/L858R expression or delete both alleles of Lkb1 and Pten. Three dimensional air-liquid-interface cultures are then used to expand the populations as organoids. For EGFR organoids, both basal and club cells give rise to larger, faster-growing bronchiolar organoids after EGFR is induced. AT2 cells similarly give rise to much larger alveolar organoids after EGFR induction, and BASCs change from giving rise to both bronchiolar and alveolar organoids to nearly exclusively alveolar. For Lkb1/Pten organoids, all four populations can tolerate deletion of the two genes, but it is only the basal cell and club cell organoids that progress to a squamous morphology in vitro. While both BASC and AT2 organoids continue to grow, they appear phenotypically normal. Transplant assays to assess malignancy and RNA-seq and ChIP-seq studies to explore gene transcription and epigenetic changes are under way. These experiments will shed light on the cells of the adult lung that give rise to genotype-specific tumors, and will aid us to better classify lung cancer heterogeneity from a cell-of-origin perspective. Citation Format: Kwok-Kin Wong, Carla Kim, Christine Fillmore Brainson. Investigating lung cancer cells-of-origin using three-dimensional organoid cultures [abstract]. In: Proceedings of the AACR Special Conference: Advances in Modeling Cancer in Mice: Technology, Biology, and Beyond; 2017 Sep 24-27; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(10 Suppl):Abstract nr PR11.