title: Interleukin-1beta (IL-1beta) and IL-6 modulate insulin-like growth factor-binding protein (IGFBP) secretion in colon cancer epithelial (Caco-2) cells.
abstract: Chronic inflammation is characterised by modifications in cytokine concentrations, whereas growth is mainly dependent on the GH-IGF axis. IGF-I bioavailability is modulated by a family of IGF-binding proteins (IGFBPs). The aim of the present study was to evaluate the interactions among interleukin-1beta (IL-1beta), IL-6 and IGFBP secretion by intestinal cells to assess whether cytokines modulate IGFBP secretion, and in turn IGF-I and IGF-II bioavailability. The human colon carcinoma derived cell line Caco-2 was used as an in vitro model for its capacity to differentiate spontaneously. Experiments were carried out on day 4 (undifferentiated state) and day 14 (differentiated state) after plating. Carcinoembryonic antigen (CEA) was used as a marker of differentiation and increased in the conditioned media (CM) from days 4 to 14 (0.2+/-0.01 ng/ml per 10(5) cells vs 3.3+/-0.2 ng/ml per 10(5) cells, P<0.05). IGFBP-2 and IGFBP-4 secretion decreased concomitantly. Cells were stimulated with IL-1beta and IL-6 at 1, 10 and 50 ng/ml, and with IL-1beta and IL-6 in combination at the same dose of 1 and 10 ng/ml. IGF-I at 50 ng/ml was used as a control. Caco-2 cells expressed and secreted mainly IGFBP-2 and IGFBP-4 into the CM. On day 4, IL-1beta (1 ng/ml) and IL-6 (10 and 50 ng/ml) reduced IGFBP-2 by 29+/-8%, and by 32+/-9 and 38+/-8% respectively (P<0.05). IGFBP-4 was also reduced by IL-1beta at 1 and 50 ng/ml (-14+/-4% and -46+/-11% vs serum free medium (SFM) respectively, P<0.05), and IL-6 at 50 ng/ml (-46+/-15%, P<0.05). Both IGFBP-2 and IGFBP-4 were reduced by IL-1beta and IL-6 in combination at 1 and 10 ng/ml (P<0.05). On day 14, IGFBP-2 band intensity was reduced at 10 ng/ml of IL-1beta (-22+/-15% vs SFM, P<0.05) and at 50 ng/ml of both cytokines (-33%+/-8% and -13%+/-13% vs baseline respectively, P<0.05). IGFBP-4 band intensity decreased with 10 and 50 ng/ml of IL-1beta (-35+/-11% and -46+/-15% vs SFM respectively) and IL-6 (-36%+/-10% and -46+/-15% vs SFM respectively). IL-1beta and IL-6 in combination at 1 and 10 ng/ml reduced both IGFBP-2 and IGFBP-4.In conclusion, IGFBP-2 and IGFBP-4 secretion in CM decreased with Caco-2 cell differentiation. IGFBP-2 and IGFBP-4 were significantly decreased by IL-1beta and IL-6 treatment in both the undifferentiated and differentiated state. Furthermore, these cytokines increased cell proliferation whereas total protein content was significantly reduced only at the higher concentrations of IL-6 and IL-1beta. These findings suggest that interleukins modulate the IGF-IGFBP system in Caco-2 cells in vitro.
authors.affiliation: Department of Endocrinology, St Bartholomew's Hospital, London, UK. mariaelisabeth.street@unipr.it
authors.forename: M E
authors.initials: ME
authors.lastname: Street
authors.forename: F
authors.initials: F
authors.lastname: Miraki-Moud
authors.forename: I R
authors.initials: IR
authors.lastname: Sanderson
authors.forename: M O
authors.initials: MO
authors.lastname: Savage
authors.forename: G
authors.initials: G
authors.lastname: Giovannelli
authors.forename: S
authors.initials: S
authors.lastname: Bernasconi
authors.forename: C
authors.initials: C
authors.lastname: Camacho-Hübner
mesh_terms: D018938:Caco-2 Cells; D002454:Cell Differentiation; D002455:Cell Division / Q000187:drug effects; D003106:Colon / Q000187:drug effects / Q000378:metabolism*; D004247:DNA / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D006801:Humans; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000378:metabolism; D018974:Insulin-Like Growth Factor Binding Protein 4 / Q000378:metabolism; D018969:Insulin-Like Growth Factor Binding Proteins / Q000378:metabolism*; D007375:Interleukin-1 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D007378:Interleukins / Q000494:pharmacology*; D014176:Protein Biosynthesis
chemical_list: D004338:Drug Combinations; D018971:Insulin-Like Growth Factor Binding Protein 2; D018974:Insulin-Like Growth Factor Binding Protein 4; D018969:Insulin-Like Growth Factor Binding Proteins; D007375:Interleukin-1; D015850:Interleukin-6; D007378:Interleukins; D004247:DNA