Alpha cell-specific Men1 ablation triggers the transdifferentiation of glucagon-expressing cells and insulinoma development.
OBJECTIVE
The tumor suppressor menin is recognized as a key regulator of pancreatic islet development, proliferation, and beta-cell function, whereas its role in alpha cells remains poorly understood. The purpose of the current study was to address this issue in relation to islet tumor histogenesis.


METHODS
We generated alpha cell-specific Men1 mutant mice with Cre/loxP technology and carried out analyses of pancreatic lesions developed in the mutant mice during aging.


RESULTS
We showed that, despite the alpha-cell specificity of the GluCre transgene, both glucagonomas and a large amount of insulinomas developed in mutant mice older than 6 months, accompanied by mixed islet tumors. Interestingly, the cells sharing characteristics of both alpha and beta cells were identified shortly after the appearance of menin-deficient alpha cells but well before the tumor onset. Using a genetic cell lineage tracing analysis, we demonstrated that insulinoma cells were directly derived from transdifferentiating glucagon-expressing cells. Furthermore, our data indicated that the expression of Pdx1, MafA, Pax4, and Ngn3 did not seem to be required for the initiation of this transdifferentiation.


CONCLUSIONS
Our work shows cell transdifferentiation as a novel mechanism involved in islet tumor development and provides evidence showing that menin regulates the plasticity of differentiated pancreatic alpha cells in vivo, shedding new light on the mechanisms of islet tumorigenesis.
Laboratoire Génétique Moléculaire, Signalisation et Cancer, Centre National de Recherche Scientifique, UMR5201, Université Claude Bernard Lyon1, Centre LEON-BERARD, Lyon, France.
Jieli
J
Lu
Pedro L
PL
Herrera
Christine
C
Carreira
Rémy
R
Bonnavion
Christelle
C
Seigne
Alain
A
Calender
Philippe
P
Bertolino
Chang Xian
CX
Zhang
D000367:Age Factors; D000375:Aging / Q000378:metabolism / Q000473:pathology; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002459:Cell Fusion; D019070:Cell Lineage; D049109:Cell Proliferation; D054338:Cell Transdifferentiation; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D005838:Genotype; D005934:Glucagon / Q000378:metabolism*; D050416:Glucagon-Secreting Cells / Q000378:metabolism* / Q000473:pathology; D005935:Glucagonoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D007328:Insulin / Q000378:metabolism; D050417:Insulin-Secreting Cells / Q000378:metabolism / Q000473:pathology; D007340:Insulinoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D010190:Pancreatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D010641:Phenotype; D011518:Proto-Oncogene Proteins / Q000172:deficiency* / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism
D015415:Biomarkers; D007328:Insulin; C484898:Men1 protein, mouse; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D005934:Glucagon