Fibroblast growth factor-2 inhibits the maturation of pro-insulin-like growth factor-II (Pro-IGF-II) and the expression of insulin-like growth factor finding protein-2 (IGFBP-2) in the human adrenocortical tumor cell line NCI-H295R

被引:30
作者
Boulle, N
Gicquel, C
Logié, A
Christol, R
Feige, JJ
Le Bouc, Y
机构
[1] Hop Trousseau, Lab Explorat Fonct Endocriniennes, F-75012 Paris, France
[2] CEA Grenoble, DBMS, BRCE, INSERM,U244, F-38054 Grenoble 9, France
[3] Hop St Antoine, INSERM, U515, F-75012 Paris, France
关键词
D O I
10.1210/en.141.9.3127
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
The IGF system is thought to play a major role in adrenocortical tumorigenesis. In this study, we used the NCI H295R cell line as a model to investigate the effects of fibroblast growth factor-2 (FGF-2), a potent mitogen for normal adrenal cells, on the proliferation and on the expression of the IGF system in cultured adrenocortical tumor cells. Three immunoreactive FGF-2 isoforms of molecular masses 18, 22, and 24 kDa were detected in H295R cell extracts. Recombinant human FGF-2 stimulated the proliferation of adrenocortical tumor cells in a dose- and time-dependent manner, with a maximal effect at a concentration of about 1 ng/ml. Treatment of H295R cells with 10 ng/ml FGF-2 for 7 days had no significant effect on IGF-II messenger RNA levels. However, a marked increase in levels of intracellular IGF-II protein was detected by immunoblotting. In contrast, FGF-2 induced a marked decrease in the amount of IGF-II protein secreted, with the disappearance of mature IGF-II and secretion of higher molecular forms of the growth factor, suggesting modifications of IGF-II processing. Cell cultures in the presence of brefeldin A (1 mu g/ml), a specific inhibitor of protein secretion, suggested that FGF-2 did not increase IGF-II synthesis but instead inhibited the secretion of pro-IGF-II from H295R cells, thereby impairing the final steps of IGF-II processing to the mature 7.5-kDa peptide. At the same concentrations, FGF-P also decreased both IGFBP-2 messenger RNA and secreted protein, which might increase IGF-II bioavailability. No proteolysis of IGFBP-2 was detected in FGF-2-conditioned medium. Altogether, these results indicate that FGF-2 is mitogenic for NCI H295R tumor cells and regulates the expression of both IGF-II and IGFBP-2 in this tumor model. Moreover, this study shows a novel effect of FGF-2, by which this growth factor modulates the processing of pro-IGF-II.
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页码:3127 / 3136
页数:10
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