Modeling MEN1 with Patient-Origin iPSCs Reveals GLP-1R Mediated Hypersecretion of Insulin

Area of Science:

• Endocrinology
• Genetics
• Stem Cell Biology

Background:

• Multiple Endocrine Neoplasia type 1 (MEN1) is an inherited disorder caused by mutations in the MEN1 gene, leading to various endocrine tumors.
• Pancreatic neuroendocrine tumors (PNETs) are a life-threatening manifestation of MEN1, with existing mouse models showing species differences and limitations in fully recapitulating human disease phenotypes.
• Human cell-based models are needed to better understand MEN1 pathogenesis and explore therapeutic strategies, especially concerning genotype-phenotype correlations.

Purpose of the Study:

• To investigate whether patient-derived induced pluripotent stem cell (iPSC) lines can effectively model key defects associated with Multiple Endocrine Neoplasia type 1 (MEN1).
• To characterize the in vitro differentiation of MEN1-iPSCs into pancreatic beta-like cells and assess their functional and molecular characteristics.
• To evaluate the tumorigenic potential of MEN1-iPSC-derived cells in vivo and identify potential therapeutic targets for MEN1-related hyperinsulinemia.

Main Methods:

• Generation and in vitro differentiation of patient-origin induced pluripotent stem cell (iPSC) lines from individuals with MEN1.
• Assessment of insulin production, insulin secretion, and proliferative activity during beta-cell differentiation.
• Analysis of gene and protein expression, including prohormone convertase1/3 (PC1/3), glucagon-like peptide-1 (GLP-1), GLP-1 receptor (GLP-1R), and the PI3K/AKT pathway.
• Pharmacological inhibition of GLP-1R and PI3K signaling pathways.
• In vivo transplantation of differentiated MEN1-iPSC-derived cells into immune-deficient mice to assess tumor formation and PNET mimicry.

Main Results:

• MEN1-iPSC derived cells exhibited a two-fold increase in insulin-positive cells and insulin secretion compared to controls, primarily due to enhanced proliferation in pancreatic progenitor stages.
• Increased expression of PC1/3, GLP-1, GLP-1R, and PI3K/AKT pathway components was observed in MEN1-iPSC derived cells, with GLP-1R localized to beta-like cells.
• Inhibition of GLP-1R or PI3K significantly reduced insulin hypersecretion and the percentage of insulin-positive cells in MEN1-derived cells.
• Transplantation studies revealed that only beta-like cells derived from MEN1-iPSCs formed tumors mimicking human PNETs.

Conclusions:

• Patient-derived iPSCs successfully model key aspects of MEN1, including hyperinsulinemia and PNET development, offering a valuable human cell resource for studying the disease.
• The study highlights the critical role of the GLP-1R and PI3K/AKT signaling pathway in MEN1-associated beta-cell dysfunction and tumor formation.
• GLP-1R emerges as a promising therapeutic target for managing MEN1-related hyperinsulinemia and potentially PNETs.