Presence of IGF-I In human midgut carcinoid tumours—an autocrine regulator of carcinoid tumour growth?
Article first published online: 18 JUL 2006
Copyright © 1992 Wiley-Liss, Inc., A Wiley Company
International Journal of Cancer
Volume 51, Issue 2, pages 195–203, 8 May 1992
How to Cite
Nilsson, O., Wängberg, B., Theodorsson, E., Skottner, A. and Ahlman, H. (1992), Presence of IGF-I In human midgut carcinoid tumours—an autocrine regulator of carcinoid tumour growth?. Int. J. Cancer, 51: 195–203. doi: 10.1002/ijc.2910510206
- Issue published online: 18 JUL 2006
- Article first published online: 18 JUL 2006
- Manuscript Revised: 24 DEC 1991
- Manuscript Received: 30 SEP 1991
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 rhlGF-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.