Abstract A025: Cell of origin does not underlie transcription heterogeneity in pancreatic ductal adenocarcinoma

Abstract Pancreatic ductal adenocarcinoma (PDAC) it though to develop through induction of different precursor lesions, however, the normal cell type that gives rise to these precancerous lesions and PDAC is unclear. Recent studies using mouse models and ex vivo cultured human cells suggest that the cellular origin of PDAC may be either acinar or ductal cells. Potential transcriptional markers associated with PDAC of different cellular origins have been identified. Here, we interrogate whether these markers are predictive of cellular of origin across models using mouse models where acinar and ductal cells (Ptf1aCreER or Sox9CreER) expressing oncogenic Kras in the absence of Trp53 or Pten give rise to PDAC tumors. We found that acinar- and ductal-cell-derived PDAC exhibit transcriptional differences both in vivo and in vitro when comparing within one genotype or sample source type (e. g. bulk tumor or primary cell lines). However, previously predicted markers of cellular origin had variable expression across models and sample types suggestive of differences specific to those sample sets. Using our larger sample sets and multiple genotypes and source types, we proposed a more comprehensive set of cell of origin markers for consideration. Application of these markers to our own data sets, however, failed to properly segregate acinar- and ductal-cell-derived PDAC into separate groups. This suggests that the transcriptional heterogeneity observed in our sample set was not driven by the tumors arising from different cellular origins. We also examined the relationship between cell of origin and patient PDAC transcriptional subtypes using our mouse model datasets. Our findings support previous research indicating that mouse models of acinar-cell-derived PDAC favor those of a classical subtype. However, our mouse PDAC samples all express similar or very low levels of the genes denoting the basal subtype, suggesting that the basal subtype was not strongly present in any of the datasets we examined. In summary, our data suggest that acinar and ductal cells converge into a very similar PDAC transcriptional state and that, if differences can be identified, they will likely be identified by non-transcript based readouts. Citation Format: Ken Chu, Alex Lee, Karnjit Sarai, Yan Dou, Wesley Hunt, Emma Croft, Atefeh Samani, Farnaz Taghizedeh, Claire Dubois, Stephane Flibotte, Janel Kopp. Cell of origin does not underlie transcription heterogeneity in pancreatic ductal adenocarcinoma abstract. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84 (17 Suppl₂): Abstract nr A025.