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No constant relationship between islet amyloid polypeptide (IAPP) and insulin expression in insulinomas
M G Nieuwenhuis1, A D van Mansfeld, J A van Unnik
1Department of Internal Medicine, University Hospital, Utrecht, Netherlands.
The Netherlands Journal of Medicine
|December 1, 1992
Summary
In insulinoma tumors, the expression of insulin and islet amyloid polypeptide (IAPP) varies. This study found no constant relationship between insulin and IAPP RNA or peptide levels in these tumors.
Area of Science:
- Endocrinology
- Molecular Biology
- Oncology
Background:
- Insulinomas are pancreatic tumors that secrete insulin.
- Islet amyloid polypeptide (IAPP) is co-secreted with insulin by pancreatic beta cells.
- The relationship between insulin and IAPP expression in insulinomas is not fully understood.
Observation:
- Three patients with insulinoma (two solitary, one MEN-I syndrome) were analyzed.
- Both normal pancreas and insulinoma tissues expressed two IAPP mRNA species.
- IAPP mRNA levels were lower than insulin mRNA in two tumors, but equal in one.
Findings:
- Amyloid deposits, detected by anti-IAPP antibodies, were present in one solitary tumor and the MEN-I tumor.
- Cytoplasmic IAPP staining was weak despite positive amyloid staining.
- A consistent relationship between insulin and IAPP expression was not observed in these insulinomas.
Implications:
- Insulinoma pathogenesis may involve dysregulated IAPP expression.
- Understanding IAPP's role could offer new therapeutic targets for insulinomas.
- Further research is needed to clarify IAPP's function in pancreatic neuroendocrine tumors.