Constitutive Insulin-like Growth Factor-II Expression Interferes with the Enterocyte-like Differentiation of CaCo-2 Cells

• Published in: The Journal of biological chemistry 1996-04, Vol.271 (14), p.8108-8114
• Main Authors: Zarrilli, R, Romano, M, Pignata, S, Casola, S, Bruni, C B, Acquaviva, A M
• Format: Article
• Language: English
• Subjects: Apolipoprotein A-I - metabolism; Caco-2 Cells; Cell Adhesion; Cell Differentiation; Cell Division; Gene Expression; Humans; Insulin-Like Growth Factor II - physiology; Intestinal Mucosa - cytology; Receptor, IGF Type 1 - physiology; RNA, Messenger - genetics; Sucrase-Isomaltase Complex - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.271.14.8108

In this study we have examined the role of insulin-like growth factor-II (IGF-II) in the differentiation of the CaCo-2 human colon carcinoma cell line. We have shown previously that IGF-II is an autocrine growth factor for CaCo-2 cells. IGF-II expression is high in proliferating, undifferentiated CaCo-2 cells and markedly decreases when cells become confluent and start to differentiate. To evaluate whether differentiation of CaCo-2 cells depends on an IGF-II related pathway, we treated cells with a blocking antibody to the IGF-I receptor that mediates most IGF-II biological effects. Treatment of preconfluent CaCo-2 cells with this antibody decreased by 40% autonomous cell proliferation and induced differentiation as shown by an increase in sucrase isomaltase activity and apolipoprotein A-I (apoA-I) mRNA levels. To examine the significance of autocrine IGF-II production in CaCo-2 cell differentiation, we generated stable CaCo-2 cell lines that constitutively express rat IGF-II under the control of a Rous sarcoma virus promoter. Sustained expression of IGF-II resulted in: ( a ) increased proliferative rate; ( b ) high IGF-I receptor number, even after reaching confluence; ( c ) increased capability of anchorage-independent growth; ( d ) inhibition of the expression of apoA-I and SI mRNAs. Analysis of several independent IGF-II-transfected clones showed an inverse correlation between IGF-II mRNA levels and expression of the differentiation markers, the cells expressing the higher levels of the transfected IGF-II being the less differentiated ones. Our data suggest that perturbation of IGF-II-mediated cell proliferation interferes with the enterocyte-like differentiation pathway of CaCo-2 cells.