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Published on: July 30, 2011
High plasma amylin/islet amyloid polypeptide levels in patients with residual medullary thyroid carcinoma after total
M Alevizaki1, S I Grigorakis, S Tseleni-Balafouta
11st Endocrine Section and Diabetes Centre, Department of Clinical Therapeutics, Alexandra University Hospital, 80, Vassilissis Sofias Avenue, 115 28 Athens, Greece. mani@OTENET.gr
Objective:
We have previously reported that amylin/islet amyloid polypeptide (IAPP) mRNA is detected in a substantial subset of medullary carcinomas of the thyroid (MTCs). The aim of this study was to determine if the amylin/IAPP gene is expressed as the IAPP peptide in MTC tissues.
Design And Methods:
In 10 patients with a histological diagnosis of MTC and with persisting or recurrent disease (basal calcitonin levels >250 pg/ml), the fasting serum insulin and plasma glucose, IAPP and calcitonin levels were measured and compared with those of 18 normal control subjects matched for age and body mass index. IAPP expression was studied by immunohistochemistry in MTCs and lymph-node metastasis tissues.
Results:
Seven of ten MTC patients had abnormally elevated IAPP levels. Plasma IAPP and serum insulin levels were correlated in both patients and controls, but the slope of the regression line was significantly higher for MTC patients. IAPP staining was detected in four out of 12 random MTC samples and in two out of five lymph-node metastases, using immunohistochemistry.
Conclusions:
These results indicate that MTC cells express IAPP at the peptide level and that this raises the peripheral plasma levels. Further studies may reveal whether this is a feature of malignant disease.
Insights
Medullary thyroid carcinoma (MTC) cells express islet amyloid polypeptide (IAPP) at the peptide level, leading to elevated plasma IAPP levels in patients. This suggests IAPP expression may be a feature of MTC malignancy.
Area of Science:
- Endocrinology
- Oncology
- Molecular Biology
Background:
- Previous studies detected islet amyloid polypeptide (IAPP) mRNA in medullary thyroid carcinomas (MTCs).
- The expression of IAPP peptide in MTC tissues remained unconfirmed.
Purpose of the Study:
- To investigate whether the amylin/IAPP gene is expressed as the IAPP peptide in MTC tissues.
- To determine if IAPP peptide expression in MTC correlates with elevated peripheral plasma levels.
Main Methods:
- Immunohistochemistry was used to study IAPP expression in MTC and lymph-node metastasis tissues.
- Fasting serum insulin, plasma glucose, IAPP, and calcitonin levels were measured in 10 MTC patients and 18 controls.
Main Results:
- Seven out of ten MTC patients exhibited abnormally elevated IAPP levels.
- IAPP peptide staining was observed in MTC samples and lymph-node metastases.
- Plasma IAPP and serum insulin levels showed a significantly steeper correlation in MTC patients compared to controls.
Conclusions:
- MTC cells express IAPP at the peptide level.
- This expression leads to increased peripheral plasma IAPP levels.
- Further research is needed to ascertain if IAPP expression is a characteristic of malignant disease.
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