Oncogenic GNAS uses PKA-dependent and independent mechanisms to induce cell proliferation in human pancreatic ductal and acinar organoids.

Ductal and acinar pancreatic organoids generated from human pluripotent stem cells (hPSCs) are promising models to study pancreatic diseases, including precursor lesions of pancreatic cancer. Genome sequencing studies have revealed that mutations in a G-protein (GNAS(R201C)) are exclusively observed in intraductal papillary mucinous neoplasms (IPMNs), one of the most common cystic pancreatic precancerous lesions. GNAS(R201C) cooperates with oncogenic KRAS(G12V/D) to produce IPMN lesions in mice; however, the biological mechanisms by which oncogenic GNAS affects the ductal and acinar exocrine pancreas are not understood. In this study, we use pancreatic ductal and acinar organoids generated from human embryonic stem cells to investigate mechanisms by which GNAS(R201C) functions. As expected, GNAS(R201C)-induced cell proliferation in acinar organoids was PKA-dependent. Surprisingly, GNAS(R201C)-induced cell proliferation independent of the canonical PKA signaling in short-term and stable, long-term cultures of GNAS-expressing ductal organoids and in an immortalized ductal epithelial cell line, demonstrating that GNAS(R201C) uses PKA-dependent and independent mechanisms to induce cell proliferation in the exocrine pancreas. Co-expression of oncogenic KRASG12V and GNAS(R201C) induced cell proliferation in ductal and acini organoids in a PKA-independent and dependent manner, respectively. Thus, we identify cell lineage-specific roles for PKA signaling driving pre-cancerous lesions and report the development of a human pancreatic ductal organoid model system to investigate mechanisms regulating GNAS(R201C)-induced IPMNs.