Abstract C075: Ror2, a Novel Key Regulator Driving Cell Fate Decisions throughout Pancreatic Carcinogenesis

Abstract Introduction Reprogramming of pancreas cell fate drives development of pancreatic ductal adenocarcinoma (PDAC). Acinar cells, the most probable origin of pancreatic cancer, undergo a rapid cell identity switch towards a duct-like phenotype upon KrasG12D expression and when combined with pancreatitis or the loss of acinar differentiation factors. Metaplastic and neoplastic duct-like cells are heterogeneous with a proportion acquiring features reminiscent of gastric lineages. While some gastric signatures are maintained in the classical PDAC subtype, they are eroded in the more aggressive, basal-like PDAC. Since subtype identity has a major impact on prognosis and therapeutic targetability, druggable targets that regulate cellular reprogramming in pancreatic cancer can be exploited to increase sensitivity to therapy. Methods To elucidate mechanisms responsible for early reprogramming, pancreatic tissue of mice with conditional KrasG12D expression and loss of Pdx1 was analyzed by single-nucleus ATAC-seq. Expression of identified target genes was studied in precancerous lesions and PDAC by using multiplex RNAscope and IHC staining. Computational analyses of publicly available sequencing data were used to establish correlation to PDAC subtype identity. Genes were functionally studied in PDAC cell lines. Results By performing snATAC-seq and RNA-seq of early transformed pancreatic tissue, we discovered that acinar cells with the combined expression of KrasG12D and loss of Pdx1 activate expression of a gastric metaplastic gene signature accompanied by elevated levels of the receptor kinase Ror2. Ror2 is also highly expressed in distinct subpopulations of metaplastic and neoplastic cells, associated with a gastric neck cell phenotype and enhanced proliferative capacity. In contrast, Ror2Low lesions are characterized by a gastric pit cell-like and a senescent phenotype. Genetic ablation of Ror2 resulted in a shift in lesion identity, enriching those with a pit cell and senescent identity. In PDAC, we found that Ror2 anti-correlates with a similar gastric pit cell phenotype that is maintained in the classical subtype PDAC, but is strongly associated with the more aggressive basal-like subtype. Overexpression of ROR2 in human PDAC cell lines with a classical differentiation induced loss of the classical gene signature as well as epithelial-to-mesenchymal transition. Moreover, ROR2 enforces a strong dependency on AKT signaling, causing increased vulnerability of ROR2-expressing cells to AKT inhibition, but increased resistance to the KRAS inhibitor MRTX1133. Conclusions We discovered Ror2 as a critical determinant of precancerous lesion as well as PDAC subtype identity. Its role in driving an aggressive PDAC phenotype that is inherently resistant to Kras inhibition suggests that inhibiting this receptor tyrosine kinase will enhance sensitivity to the new generation of targeted therapies. Citation Format: Simone Benitz, Alec Steep, Malak Nasser, Jonathan Preall, Ujjwal Mukund Mahajan, Holly McQuithey, Ian Loveless, Erick T. Davis, Hui-Ju Wen, Daniel W. Long, Thomas Metzler, Samuel Zwernik, Michaela Louw, Donald Rempinski, Daniel Salas-Escabillas, Sydney Brender, Linghao Song, Ling Huang, Brian K. Theisen, Zhenyu Zhang, Nina G. Steele, Ivonne Regel, Filip Bednar, Howard C. Crawford. Ror2, a Novel Key Regulator Driving Cell Fate Decisions throughout Pancreatic Carcinogenesis 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 C075.