Genetic and pharmacologic abrogation of Snail1 inhibits acinar-to-ductal metaplasia in precursor lesions of pancreatic ductal adenocarcinoma and pancreatic injury.

Pancreatic cancer (PDAC) is one of the most dismal of human malignancies. Inhibiting or delaying the progression of precursor lesions of PDAC, pancreatic intraepthial neoplasia (PanINs), to invasive cancer, would be a major step. In the present study, we used a transgenic murine model of pancreatic cancer to evaluate the impact of a conditional knockout of the transcription factor Snail1, a major factor in epithelial-to-mesenchymal transition, on acinar-to-ductal formation and on PanIN progression. By interbreeding conditional LsL-Snail ^floxf/wt ; LsL-Kras ^G12D and Pdx1-Cre strains, we obtained LsL-Kras ^G12D ;Pdx1-Cre(KP) mice, Snail1 heterozygous knockout LsL-Kras ^G12D ; LsL-Snail ^flox/- ;Pdx1-Cre(KPS ^het ) mice or Snail1 homozygous knockout LsL-Kras ^G12D ;LsL-Snail ^flox/flox ;Pdx1-Cre(KPS) mice. Mice were then followed in a longitudinal study for 2, 4, 6, 8, 10, and 12 months. Furthermore, in mice with a genetic or pharmacological inhibition of Snail1, using the Snail1 inhibitor GN25, a model of pancreatic injury by administration of cerulein was introduced to evaluate ADM formation in this setting. A translational approach with a tissue microarray (TMA) of human PanINs and an in vivo nude mouse platform to test GN25 in human pancreatic adenocarcinoma was then adopted. Quantification of PanINs showed delayed initiation and progression of PanIN lesions at all ages in both homozygous and heterozygous Snail ^del1 ;Pdx-1-Cre;LSL-Kras ^G12D/+ -Mice. PanINs at TMA revealed snail expression in the majority of cases. GN25 showed growth inhibition in 2/2 human pancreatic adenocarcinomas using a nude mice in vivo platform. Genetic and pharmacologic abrogation of Snail1 signaling in exocrine pancreas impairs development of acinar-to-ductal metaplasia following cerulein-mediated pancreatic injury. The present study suggests a fundamental new approach to delay the progression of PDAC.