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Expression of insulin‐like growth factor‐II and insulin‐like growth factor binding proteins during Caco‐2 cell proliferation and differentiation
Author(s) -
Park Jung H. Y.,
Corkins Mark R.,
Vanderhoof Jon A.,
Caruso Nia M.,
Hrbek Marjorie J.,
Schaffer Beverly S.,
Slentz Dorothy H.,
McCusker Robert H.,
MacDonald Richard G.
Publication year - 1996
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/(sici)1097-4652(199602)166:2<396::aid-jcp18>3.0.co;2-9
Subject(s) - biology , growth factor , insulin like growth factor binding protein , caco 2 , cell culture , fetal bovine serum , messenger rna , northern blot , endocrinology , insulin like growth factor , cell growth , microbiology and biotechnology , cellular differentiation , medicine , gene expression , secretion , cell , receptor , biochemistry , gene , genetics
The components of the insulin‐like growth factor (IGF) axis and their roles in regulating proliferation and differentiation of the human colon adenocarcinoma cell line, Caco‐2, have been investigated. Caco‐2 cells proliferated in serum‐free medium at 75% the rate observed in medium containing 10% fetal bovine serum. IGF‐I (10 nM) increased Caco‐2 cell growth in serum‐free medium, but not to the rate seen with serum. Multiple IGF‐II mRNA species were produced by Caco‐2 cells, but IGF‐I mRNA was undetectable. Secretion of radioimmunoassayable IGF‐II corresponded with steady‐state levels of IGF‐II mRNA, neither of which was observed to change markedly over the course of 16 days of Caco‐2 cell differentiation. Levels of sucrase‐isomaltase mRNA, a marker for enterocytic differentiation, increased 12‐fold between days 5 and 16 of culture. Northern blotting of total RNA and ligand blot and immunoblot analyses of serum‐free conditioned medium revealed that Caco‐2 cells produce several IGF binding proteins (IGFBPs), including IGFBP‐2, ‐3, and ‐4, as well as a 31,000 M, species that was not identified. The pattern of IGFBP secretion changed dramatically during Caco‐2 cell differentiation: IGFBP‐3 and IGFBP‐2 increased 8.5‐fold and 5‐fold, respectively, whereas IGFBP‐4 and the 31,000 M, species decreased 43% and 90%. Caco‐2 cell clones stably transfected with a human IGFBP‐4 cDNA construct exhibited a 60% increase in steady‐state level of IGFBP‐4 mRNA, and secreted twice as much IGFBP‐4 protein as controls. Moreover, IGFBP‐4‐overexpressing cells proliferated at only 25% the rate of control cells in serum‐free medium, in conjunction with a 70% increase in expression of sucrase‐isomaltase. In summary, these studies indicate that a complex IGF axis is involved in autocrine regulation of Caco‐2 cell proliferation and differentiation. © 1996 Wiley‐Liss, Inc.