Islets of Langerhans from prohormone convertase-2 knockout mice show α-cell hyperplasia and tumorigenesis with elevated α-cell neogenesis.
Antagonism of the effects of glucagon as an adjunct therapy with other glucose-lowering drugs in the chronic treatment of diabetes has been suggested to aggressively control blood glucose levels. Antagonism of glucagon effects, by targeting glucagon secretion or disabling the glucagon receptor, is associated with α-cell hyperplasia. We evaluated the influence of total glucagon withdrawal on islets of Langerhans using prohormone convertase-2 knockout mice (PC2-ko), in which α-cell hyperplasia is present from a young age and persists throughout life, in order to understand whether or not sustained glucagon deficit would lead to islet tumorigenesis. PC2-ko and wild-type (WT) mice were maintained drug-free, and cohorts of these groups sampled at 3, 12 and 18 months for plasma biochemical and morphological (histological, immunohistochemical, electron microscopical and image analytical) assessments. WT mice showed no islet tumours up to termination of the study, but PC2-ko animals displayed marked changes in islet morphology from α-cell hypertrophy/hyperplasia/atypical hyperplasia, to adenomas and carcinomas, these latter being first encountered at 6-8 months. Islet hyperplasias and tumours primarily consisted of α-cells associated to varying degrees with other islet endocrine cell types. In addition to substantial increases in islet neoplasia, increased α-cell neogenesis associated primarily with pancreatic duct(ule)s was present. We conclude that absolute blockade of the glucagon signal results in tumorigenesis and that the PC2-ko mouse represents a valuable model for investigation of islet tumours and pancreatic ductal neogenesis.
Department of Pathological Sciences, AstraZeneca Pharmaceuticals, Macclesfield, Cheshire, UK.
Huw B
HB
Jones
Jaimini
J
Reens
Simon R
SR
Brocklehurst
Catherine J
CJ
Betts
Sue
S
Bickerton
Alison L
AL
Bigley
Richard P
RP
Jenkins
Nicky M
NM
Whalley
Derrick
D
Morgan
David M
DM
Smith
D000236:Adenoma / Q000378:metabolism / Q000473:pathology; D000818:Animals; D063646:Carcinogenesis / Q000378:metabolism / Q000473:pathology*; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000378:metabolism / Q000473:pathology*; D004195:Disease Models, Animal; D058750:Epithelial-Mesenchymal Transition; D005260:Female; D005934:Glucagon / Q000037:antagonists & inhibitors / Q000378:metabolism; D050416:Glucagon-Secreting Cells / Q000378:metabolism / Q000473:pathology*; D006965:Hyperplasia; D007515:Islets of Langerhans / Q000378:metabolism / Q000473:pathology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010190:Pancreatic Neoplasms / Q000378:metabolism / Q000473:pathology; D045706:Proprotein Convertase 2 / Q000172:deficiency* / Q000235:genetics* / Q000378:metabolism
D005934:Glucagon; D045706:Proprotein Convertase 2
islet tumours; prohormone convertase-2 knockout mouse; α-cell hyperplasia; α-cell neogenesis; α-cell tumorigenesis