Insulin-like growth factors induce apoptosis as well as proliferation in LIM 1215 colon cancer cells.

The insulin-like growth factor (IGF) system plays an important role in cell proliferation and survival. However, more recently, a small number of studies have shown that IGFs induce apoptosis in some cells. Our initial studies showed this occurred in LIM 1215 colon cancer cells but not RD rhabdomyosarcoma cells.

Contributions of the N- and C-terminal domains of IGF binding protein-6 to IGF binding.

Insulin-like growth factors IGF-I and IGF -II are important mediators of growth. A family of six high affinity IGF binding proteins (IGFBPs) modulate IGF action. IGFBPs have three domains, of which the N- and C-domains are involved in high affinity IGF binding.

Improved contractile function of the mdx dystrophic mouse diaphragm muscle after insulin-like growth factor-I administration.

Limited knowledge exists regarding the efficacy of insulin-like growth factor I (IGF-I) administration as a therapeutic intervention for muscular dystrophies, although findings from other muscle pathology models suggest clinical potential. The diaphragm muscles of mdx mice (a model for Duchenne muscular dystrophy) were examined after 8 weeks of IGF-I administration (1 mg/kg s.c.

Insulin-like growth factors decrease catecholamine content in PC12 rat pheochromocytoma cells.

Insulin-like growth factors (IGFs) stimulate proliferation and differentiation of PC12 rat pheochromocytoma cells and modulate catecholamine release in bovine adrenal medullary cells. Dexamethasone increases catecholamine synthesis in PC12 cells. We therefore studied the effects of IGFs and dexamethasone on catecholamine content in PC12 cells.

Insulin-like growth factor-II renders LIM 2405 human colon cancer cells resistant to butyrate-induced apoptosis: a potential mechanism for colon cancer cell survival in vivo.

Butyrate has potent anti-tumorigenic effects on many colon cancer cell lines, including inhibition of growth and promotion of apoptosis in vitro. Nevertheless, despite the butyrate concentration in the colonic lumen being sufficient to result in the death of almost all cells in vitro, colon cancers still develop and grow in vivo, suggesting that cancer cells must develop mechanisms by which they escape the effects of butyrate observed in vitro. Insulin-like growth factor-II (IGF-II) is an autocrine growth factor in many colon cancer cells.

Insulin-like growth factor (IGF)-binding protein-6 inhibits IGF-II-induced but not basal proliferation and adhesion of LIM 1215 colon cancer cells.

IGF-II is an autocrine growth factor for many colon cancer cells. This study aimed to determine the role of IGF-II in proliferation and adhesion of LIM 1215 colon cancer cells. RT-PCR demonstrated expression of IGF-I and IGF-II mRNA.

Cyclic AMP agonists increase levels of insulin-like growth factor (IGF) binding protein-6 in PC12 rat phaeochromocytoma cells.

The predominant insulin-like growth factor binding protein (IGFBP) synthesized by PC12 rat phaeochromocytoma cells is IGFBP-6. Since cAMP agonists regulate IGFBP-6 in other cells, and they may increase neurite outgrowth and catecholaminergic enzyme expression in PC12 cells, we studied regulation of IGFBP-6 by these agents. After 72 h incubation, forskolin and 8-(4-chlorophenylthio)-cAMP (CPT-cAMP) both increased IGFBP-6 protein levels in conditioned media to maximum levels of 231 +/- 40 and 275 +/- 30%, respectively.

O-glycosylation of insulin-like growth factor (IGF) binding protein-6 maintains high IGF-II binding affinity by decreasing binding to glycosaminoglycans and susceptibility to proteolysis.

Insulin-like growth factor binding protein-6 (IGFBP-6) is an O-linked glycoprotein which specifically inhibits insulin-like growth factor (IGF)-II actions. The effects of O-glycosylation of IGFBP-6 on binding to glycosaminoglycans and proteolysis, both of which reduce the IGF binding affinity of other IGFBPs were studied. Binding of recombinant human nonglycosylated (n-g) IGFBP-6 to a range of glycosaminoglycans in vitro was approximately threefold greater than that of glycosylated (g) IGFBP-6.

Induction of insulin-like growth factor binding protein expression by ICI 182,780 in a tamoxifen-resistant human breast cancer cell line.

Earlier studies in our laboratory demonstrated that the steroidal antiestrogen ICI 182,780 is very effective in abolishing the tamoxifen-resistant proliferation of MCF 7/5-23 cells. In addition, preliminary binding studies showed that ICI 182,780 increased the binding of insulin-like growth factor (IGF)-I to the MCF 7/5-23 cells, although this finding was not the result of an increase in the expression of the insulin-like growth factor-I receptor (IGF-IR). Hence, we reasoned that the inhibition of tamoxifen-resistant cell growth by ICI 182,780 might have been due to increased expression of insulin-like growth factor binding proteins (IGFBPs).

HaCaT human keratinocytes express IGF-II, IGFBP-6, and an acid-activated protease with activity against IGFBP-6.

The insulin-like growth factor (IGF) system plays an important role in skin. HaCaT human keratinocytes proliferate in response to IGFs and synthesize IGF-binding protein-3 (IGFBP-3). Recently, IGFBP-6 was also identified by NH2-terminal sequencing, but it has not been identified by Western ligand blotting.

Regulation of IGF-binding protein-6 by dexamethasone and IGFs in PC12 rat phaeochromocytoma cells.

PC12 rat phaeochromocytoma cells are widely used as a model of neuronal differentiation. They express IGF receptors and are responsive to IGFs. The main IGF-binding protein synthesized by these cells is IGFBP-6.

Roles of insulin-like growth factor (IGF) receptors and IGF-binding proteins in IGF-II-induced proliferation and differentiation of L6A1 rat myoblasts.

Insulin-like growth factor II (IGF-II) stimulates the proliferation and differentiation of rat myoblasts. Previous studies suggest that these response are mediated by the IGF-I receptor, but the IGF-II/mannose 6-phosphate receptor was recently implicated in differentiation of mouse myoblasts. L6A1 myoblasts synthesize IGF-binding protein-4 (IGFBP-4), IGFBP-5, and IGFBP-6, which modulate IGF action.