Background: Congenital hyperinsulinism of infancy (CHI) mainly arises from loss-of-function mutations in the KATP channel genes. As a consequence, insulin release is uncontrolled and causes persistent or recurrent episodes of hypoglycaemia in neonates. In patients with diffuse-CHI (CHI-D) increased rates of cell proliferation has been reported, but the causes of proliferation are unknown.
Objective/Hypotheses: To assess the extent of cell proliferation and the role of CDK6 in control of the cell cycle in the CHI-D pancreas.
Methods: We used immunostaining in paraffin-embedded samples of CHI-D (n=7, 213 months), age-matched control pancreata (n=6, 6 weeks13 months) and foetal pancreas (10 weeks post-conception) to examine the extent of proliferation in different cell types including α- (glucagon+), β- (insulin+), ductal (SOX9+), and exocrine (GATA4+) cells. Ki67 was used to document cell proliferation and to define the proliferative index of the pancreas through high-content analysis of digital images. The control of cell proliferation was investigated via immunostaining of the cell cycle regulator CDK6.
Results: In controls we found Ki67 staining correlated inversely with age between 6 weeks and 1 year after birth (rs=−0.929, P<0.01). In contrast, proliferation remained elevated in all cell types in CHI-D with SOX9-, GATA4-, and insulin-positive cells reaching statistical significance, P<0.01. By analysing regions of tissue each containing 20 00030 000 cells we found that, on average, 4.3±0.1% of the CHI pancreas was proliferative (n=3 cases) compared to 36.3±8% of the foetal pancreas. CDK6 was detected in the cytoplasm of control islets where it colocalised with insulin. By comparison, in CHI-D, CDK6 was strongly nuclear in islet-, exocrine- and a sub-fraction of ductal-cells.
Conclusion: CHI-D retains high rates of proliferation in SOX9-, GATA4-, and insulin-positive cell types compared to age-matched controls. Detection of nuclear-localised CDK6 in these cells supports a role for CDK6 in inappropriate cell proliferation.
20 - 22 Sep 2014
European Society for Paediatric Endocrinology