Des‐(1–3)‐IGF‐I, an insulin‐like growth factor analog used to mimic a potential IGF‐II autocrine loop, promotes the differentiation of human colon‐carcinoma cells

Abstract

HT29-D4 human colon-carcinoma cells have been shown to secrete insulin-like growth factor (IGF)-II and to simultaneously express type-I IGF receptors. However, the sequestration of IGF-II by several molecular forms of IGF-binding proteins (IGFBP) in the culture medium prevents the establishment of an operative IGF-II autocrine loop. IGFBPs secreted by HT29-D4 cells (HT29-D4 IGFBP) comprise isoforms of IGFBP-4 (25, 27 and 30 kDa) and 2 unidentified forms (34.5 and 32-34 kDa). This latter does not bind 125I-IGF-I. The net affinity of HT29-D4 IGFBP is about 12 times stronger for IGF-II (KD approx. 10(-10) M) than for IGF-I. All the HT29-D4 IGFBP molecular forms are unable to bind the N-terminally truncated IGF-I analog, des-(1-3)-IGF-I. In contrast, HT29-D4 cell-surface type-I IGF receptors bind IGF-I and des-(1-3)-IGF-I identically (KD approx. 5 x 10(-10) M). We have taken advantage of these particular binding properties to use des-(1-3)-IGF-I to mimic a potential IGF autocrine loop and to observe its biological consequences. Nanomolar concentrations of des-(1-3)-IGF-I induce HT29-D4 cells to develop into a differentiated phenotype, as judged by a substantial carcinoembryonic antigen release and the induction of numerous intercellular cysts with well-organized microvilli. In the same way, des-(1-3)-IGF-I early induces a slight inhibition of HT29-D4 cell proliferation. Based on these findings, we conclude that the type-I IGF receptor primarily controls the differentiation of these colonic cells, and that HT29-D4 cancer cells remain in an undifferentiated state because of their inability to use endogenous IGF-II as an autocrine regulatory factor.

Prevention of cytokine-induced apoptosis by insulin-like growth factor-I is independent of cell adhesion molecules in HT29-D4 colon carcinoma cells–evidence for a NF-κB-dependent survival mechanism

“…21 For these studies, tissue culture plastic wells were coated overnight at 48C with 10 mg/ml of type IV collagen (Sigma, L'Isle d'Abeau, France), vitronectin (prepared as described previously), 27 30 mg/ml of fibronectin (Sigma), laminin-1 (prepared as described previously), 27 or 10 mg/ml of PLL (Sigma). For suspension cultures, tissue culture wells were coated with poly-(2-hydroxyethyl methacrylate) (poly-HEMA) (Sigma) following the protocol reported by Folkman and Moscona.…”

“…18 ± 20 By using the HT29-D4 human colon carcinoma cell model, we have shown that two key processes, enterocyte-like differentiation and cell migration, were under the control of the IGF system. 21,22 In addition, we recently reported that IGF-I, IGF-II and insulin induce a strong resistance in HT29-D4 cells to apoptosis triggered by TNF in IFNsensitized cells. 23 Increasing evidence shows that a collaboration between integrin-, E-cadherin-and growth factor-mediated signaling pathways is required for the cells to mount appropriate biological responses.…”

Cell polarity of the insulin-like growth factor system in human intestinal epithelial cells. Unique apical sorting of insulin-like growth factor binding protein-6 in differentiated human colon cancer cells.

“…These differentiated cells are highly polarized with mature junctional complexes, well-organized microvilli, and functional specialized apical and basolateral membrane domains which are characterized by an asymmetric distribution of plasma membrane markers (7)(8)(9). On the other hand, we have previously presented evidence that suggests the involvement of a regulatory insulin-like growth factor-II (IGF-II) autocrine loop in the control of the differentiation state of HT29-D4 cells (10,11). The inability of these cells to differentiate when grown in a standard culture medium (HT29-D4-GLU cells), would be due, in part, to their incapacity to use the regulatory potential of endogenous IGF-II because of its complete sequestration in the extracellular medium by different molecular species of IGF binding proteins (IGFBPs)' (12).…”

“…The inability of these cells to differentiate when grown in a standard culture medium (HT29-D4-GLU cells), would be due, in part, to their incapacity to use the regulatory potential of endogenous IGF-II because of its complete sequestration in the extracellular medium by different molecular species of IGF binding proteins (IGFBPs)' (12). The shunt of this IGFBPs inhibitory activity indeed allows IGF-II to interact with cell surface type I IGF receptors and to induce a differentiated phenotype in HT29-D4 cells (10,11). Six differ- 1.…”

The Efficacy of IGF-I Receptor Monoclonal Antibody against Human Gastrointestinal Carcinomas is Independent of k-ras Mutation Status

“…IGFs stimulate the proliferation of GI cancer cells and blocking of IGF-IR signaling inhibits tumor growth (9,(12)(13)(14)(15)(16)(17)(18)(19)(20). High serum concentration of IGF-I increases the risk of developing several cancers (10).…”