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Presence of IGF-I in Human Midgut Carcinoid Tumours--An Autocrine Regulator of Carcinoid Tumour Growth?

Presence of IGF-I in Human Midgut Carcinoid Tumours--An Autocrine Regulator of Carcinoid Tumour Growth?

O Nilsson, B Wängberg, E Theodorsson, A Skottner, H Ahlman

Int J Cancer. 1992 May 8;51(2):195-203.

PMID: 1314781

Abstract:

The presence of IGF-I and IGF-I receptors in human midgut carcinoid tumours has been investigated. Using immunocytochemistry, IGF-I-positive tumour cells were demonstrated in 11/11 tumour cases studied. Labelling of consecutive sections with antibodies against IGF-I and proliferating cell nuclear antigen (PCNA)/cyclin demonstrated a co-distribution of the 2 antigens in carcinoid tumours. Extracts of tumour tissues were subjected to radioimmunoassay and shown to contain significant amounts of IGF-I. Reverse-phase HPLC of tumour extracts demonstrated a major IGF-I-immunoreactive component eluting in the position of rhIGF-I, but also 2 other more hydrophobic forms. Conditioned serum-free media from primary cultures of carcinoid tumors contained detectable amounts of IGF-I, indicating a spontaneous release of IGF-I from tumour cells into the culture medium. Levels of IGF-I in media were reduced (19%) after incubation of cultures with a somatostatin analogue for 4 days. IGF-I receptors were observed on tumour cells in 4/10 tumours by immunocytochemistry. Tumour cells with immunoreactive IGF-I receptors could be stimulated to enhanced growth, measured as an increase in DNA contents, by exogenous administration of IGF-I every 3-4 days for 2 weeks. The results show that cultured human midgut carcinoid tumours secrete IGF-I and that some of the tumours also have IGF-I receptors. We therefore suggest that IGF-I may act as an autocrine or paracrine regulator of carcinoid tumour-cell growth.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
IAR42413310	IGF-I human			Price

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