Abstract A073: Desmoglein-2 is a regulator of pancreatic ductal adenocarcinoma progression

Abstract Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies, with a dismal 5-year survival rate of 13%. We have discovered that desmoglein-2 (DSG2), a cell surface protein, is highly expressed on PDAC cells. In silico data indicate that elevated levels of DSG2 is associated with PDAC progression and poor patient survival. Immunohistochemistry (IHC) analysis of a tissue microarray of 302 patient samples showed that DSG2 was expressed by 90% of PDAC patients. We hypothesized that DSG2 is an under-appreciated contributor to PDAC progression and that DSG2 can be targeted. The main aims of this study were to: 1) investigate the role of DSG2 in PDAC cell function in vitro, 2) investigate the molecular biology underpinning the role of DSG2 in PDAC, and 3) to use murine PDAC tumor models to evaluate the contribution of DSG2 to cancer progression in vivo. Our in vitro data showed that reducing the expression of DSG2 (via small interfering RNA (siRNA) ) significantly decreased PDAC cell proliferation, migration, and invasion. Moreover, signaling analysis of PDAC cells with or without DSG2 (via siRNA) using a reverse-phase protein array and cytokine array revealed that DSG2 modulates pro-tumorigenic and pro-metastatic cellular pathways, through reducing the effects of certain proteins. Particular alterations were observed in pathways involving gene regulation (e. g. , beta-catenin), migration (e. g. , epidermal growth factor receptor and integrin-beta1), and cytokine release (e. g. , serpine-1). Next, in an orthotopic xenograft mouse model, BxPC-3 PDAC cells with a stable knockdown of DSG2 (via short-hairpin RNA) were injected into NSG (NOD scid gamma) mice, where we observed a significant reduction in tumor burden and liver metastasis when compared to control mice. IHC staining of tumor sections revealed that the DSG2 knockdown tumors contained reduced levels of collagen, tumor vasculature and cancer associated fibroblasts. Thus, suggesting that DSG2 also has a modulatory effect on the tumor microenvironment (TME). A similar reduction in tumor burden, cancer progression and changes to the TME were observed when a neutralizing anti-DSG2 monoclonal antibody was administered intraperitoneally twice a week at 5mg/kg to BxPC-3 tumor bearing mice. Finally, to investigate the immune cell landscape, we used an orthotopic syngeneic mouse model, whereby Dsg2 was knocked out of KPC (LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre) mouse PDAC cells via clustered regularly interspaced short palindromic repeats (CRISPR) /Cas9. This mouse model also showed that loss of Dsg2 resulted in a significant reduction in tumor burden, cancer cell metastasis and changes to the TME. In summary, we have identified a potential new target for the treatment of PDAC, namely DSG2, and future experiments are pursuing clinical opportunities to improve PDAC patient survival. Citation Format: Charlie B Ffrench, Kay K Myo Min, Mark DeNichilo, Michaelia P Cockshell, Emma L Dorward, Emma J Thompson, Michael Ortiz, Michael S Samuel, Savio George Barreto, Claudine S Bonder. Desmoglein-2 is a regulator of pancreatic ductal adenocarcinoma progression 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 A073.