McCune-Albright syndrome and IPMN formation modelled in GNAS-mutated duct-like organoids derived from human pluripotent stem cells

One of the early key drivers frequently mutated in intraductal papillary mucinous neoplasia (IPMN) of the pancreas is the GNAS gene with a hotspot mutation at codon 201. McCune-Albright syndrome (MAS) is caused by such a dominant activating GNAS mutation occurring in a post-zygotic mosaic pattern. Besides other manifestations, including characteristic polycystic fibrous dysplasia, patients show an increased risk of developing pancreatic cysts and PDAC. We aimed to develop an appropriate MAS model using human pluripotent stem cells (hPSCs) to investigate the molecular basis by which GNAS mutations cause IPMN formation.

Here, we have implemented a novel in vitro differentiation platform to efficiently induce pancreatic duct-like organoids (PDLOs) from hPSCs. MAS-patient-derived cells were reprogrammed to generate induced pluripotent stem cell (iPSC) lines only differing in the GNAS mutation status. Second, using a piggyBac system, hESCs were engineered to inducibly express GNAS^R201H and KRAS^G12D.

Upon ductal commitment, GNAS^WT/R201C MAS-iPSCs formed large cystic PDLOs dramatically increasing in size compared to PDLOs from isogenic GNAS^WT/WT lines. Besides enhanced proliferation, we identified the GNAS-PKA-VASP signalling axis to be important for cystic growth of GNAS^WT/R201C PDLOs. Overexpression of GNAS^R201H within hESC-derived PDLOs faithfully recapitulated MAS patient data evident by pronounced cystic growth in vitro. After transplantation into the mouse pancreas, mutant GNAS expressing PDLOs developed well-differentiated cystic ducts resembling human IPMNs. Additive KRAS^G12D induction led to far larger IPMN-like structures with a higher degree of cellular atypia, more pseudo-papillae, and less proliferation.

These results indicate that we were able to recapitulate IPMN features in hPSC-derived organoids in vitro and in vivo. Together, our approach provides analytical access to early stages of disease development and allows to determine the effect of specific cancer driver mutations on duct-like cells with the genetic background of a cancer predisposition syndrome. This will offer new possibilities for studying tumour initiation and progression in a genetically defined humanized disease model as perquisite for personalized therapies.

Publication History

Article published online:
08 September 2020