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Islet amyloid polypeptide (IAPP). A short review
1Department of Clinical Chemistry, University Hospital, Uppsala, Sweden.
Acta Oncologica (Stockholm, Sweden)
|January 1, 1991
Summary
Islet amyloid polypeptide (IAPP) is linked to type II diabetes and pancreatic tumors. High IAPP levels can inhibit insulin secretion, suggesting its use as a tumor marker.
Area of Science:
- Endocrinology
- Molecular Biology
- Oncology
Background:
- Islet amyloid polypeptide (IAPP) is a 37-amino acid peptide found in pancreatic beta-cells, co-stored and co-secreted with insulin.
- IAPP shares homology with calcitonin gene-related peptide (CGRP) and its sequence promotes islet amyloidosis, a factor in type II diabetes development.
- Reduced IAPP and insulin levels are observed in beta-cell depletion states like type I diabetes.
Purpose of the Study:
- To investigate the role of IAPP in pancreatic islet cell tumors and its effect on glucose-stimulated insulin secretion.
- To establish a radioimmunoassay for measuring plasma IAPP levels.
Main Methods:
- Development of a radioimmunoassay for plasma IAPP measurement.
- Immunohistochemical analysis of pancreatic islet cell tumors.
- Oral glucose tolerance testing in a patient with extremely elevated IAPP levels.
Main Results:
- A patient with a pancreatic islet cell tumor exhibited extremely elevated plasma IAPP levels (approx. 20,000 pmol/l) with confirmed IAPP content and amyloid deposits.
- During an oral glucose tolerance test, insulin levels remained unchanged, while glucose and IAPP levels increased.
- High plasma IAPP levels were found to inhibit glucose-stimulated insulin secretion.
Conclusions:
- IAPP can serve as a valuable tumor marker for pancreatic islet cell tumors.
- Elevated plasma IAPP levels can impair glucose-stimulated insulin secretion, potentially contributing to hyperglycemia.