Abstract C061: Loss of CaMK2B accelerates tumor formation and enhances metastatic competency in genetically engineered mouse models of PDAC

Abstract Background Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer- related deaths in the United States and is often not diagnosed until it has already metastasized. Our prior work established that calcium signaling pathways facilitate a pro-metastatic phenotype through the induction of an epithelial-to-mesenchymal transition (EMT) program in PDAC tumor cells, but the downstream signaling molecules mediating this phenotype have remained elusive. MethodsUsing a novel genetically engineered model of pancreatic cancer, we demonstrate that loss of Calcium/calmodulin-dependent kinase-II B (CaMK2B), a downstream effector kinase activated by calcium, enhances cellular plasticity, and increases metastasis. To this end, we generated a genetically engineered mouse model where Camk2b was knocked out in tumor cells in a lineage-labeled Kras- and p53-driven PDAC mouse model (herein KPCY-Camk2bcKO). Results Genetic deletion of Camk2b in the KPCY genetically engineered model accelerated tumor formation and dramatically reduced the overall median survival of KPCY- Camk2b cKO mice (78 days) relative to KPCY controls (136 days). Pathological and immunofluorescence analysis of KPCY-Camk2b cKO animals showed an increased number of poorly differentiated tumor regions and a higher metastatic burden, with 85% of KPCY- Camk2b cKO animals presenting with multi-focal metastases. Further analysis of tumor cells in KPCY-Camk2b cKO mice showed enhanced expression of markers of the highly aggressive squamous PDAC subtypes. Strikingly, Camk2b deletion combined with oncogenic Kras G12D (in the absence of p53 alterations), was sufficient to form lethal metastatic PDAC tumors, while age-matched control Kras G12D tumors with intact Camk2b only progressed to the acinar-to-ductal metaplasia (ADM) or Pancreatic Intraepithelial Neoplasia (PanIN) stage. Collectively, these results establish Camk2b loss as a new oncogenic and pro-metastatic mechanism in PDAC Conclusion This work demonstrates that Camk2b loss enhances tumor cell evolution and plasticity within PDAC to promote metastasis. In this context, we speculate that loss of Camk2b rewires calcium signaling to drive an aggressive subtype of PDAC with increased metastasis. Citation Format: Jessica Peura, Nikita Bhalerao, Calvin Johnson, Yamini Ogoti, Faith Keller, Emma Watson, Zhen Zhao, Jason Pitarresi. Loss of CaMK2B accelerates tumor formation and enhances metastatic competency in genetically engineered mouse models of PDAC 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 C061.