Abstract A069: Development of an AAV-mediated GEM model to investigate the impact of age on pancreatic tumorigenesis
Authors: Duong-Polk Karen XD , Neff Madelaine , Commisso Cosimo 
Published: September 2024

Abstract
Much of our understanding of PDAC initiation comes from Genetically Engineered Mouse (GEM) models where a pancreas-specific Cre (such as Pdx- or p48-Cre) drives expression of specific mutations. While these GEM models generally recapitulate the key histopathological features of human PDAC, they have limitations when it comes to studying the impact of age on PDAC initiation since the Cre drivers induce recombination at the embryonic stage. This is an important consideration since in humans the disease manifests later in life, with the median age at diagnosis being 70 years old. Here, we describe the development of an intrapancreatic injection model using adeno-associated virus (AAV) to study how age influences PDAC initiation and the dynamics of tumor progression. This new viral transduction-based mouse model employs AAV-Cre to induce expression of an oncogenic KRasG12D allele together with a Trp53R172H tumor suppressor mutation within the pancreata of mice at different ages. Our approach utilizes mice with the genotype LSL-KrasG12D; LSL-Trp53R172H that are injected with different AAV-Cre directly into the parenchyma of the pancreas. In our initial studies, we used rAAV vectors expressing Cre recombinase and EGFP (AAV-Cre-EGFP) into young mice (10-14 weeks old) and older mice (32 weeks old) and analyzed EGFP expression using IVIS imaging and immunohistochemistry (IHC) at various timepoints post-injection. To evaluate tumor initiation, we assessed the extent of PanIN lesion formation using H&E staining. Our preliminary findings indicate that AAV-Cre-EGFP effectively transduces cells in vivo and triggers tumor development in the pancreas. To account for potential immunogenicity of the fluorescent protein, we then used rAAV vectors lacking EGFP expression. As controls, we administered identical rAAV vectors to wild-type cohorts matched for age and sex, along with mock injections. Transduction efficiency within the pancreas was determined by evaluating Cre and p53 expression levels, given that the R172H mutation stabilizes the protein. Notably, we found that EGFP is not necessary for either successful transduction or tumor initiation. We are currently evaluating PDAC initiation using a wide spectrum of ages, but our preliminary data using this model suggest that increased age may impact tumor progression, and that this effect may be sex-specific. Our novel AAV-Cre injection model holds promise for investigating age-related aspects of PDAC initiation, and in the future, such approaches could be leveraged to investigate how age impacts the effectiveness of different therapeutic modalities.
Citation Format: Karen XD Duong-Polk, Madelaine Neff, Cosimo Commisso. Development of an AAV-mediated GEM model to investigate the impact of age on pancreatic tumorigenesis [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 Suppl_2):Abstract nr A069.