Insulin-like growth factor-II as a paracrine growth factor in human neuroblastoma cells.
The human neuroblastoma line, SK-N-SH, has been subcloned into SH-SY5Y, a neuroblast N cell line, and SH-EP, an epithelial Schwann S cell line. We have previously shown that SH-SY5Y neuroblastoma cells produce insulin-like growth factor II (IGF-II), which acts by an autocrine mechanism to stimulate cell growth. In the current study, we examined the effect of IGF-II on SH-EP neuroblastoma cells. Northern blot and reverse transcriptase-polymerase chain reaction analyses indicate that SH-EP cells do not produce IGF-I or IGF-II but express the type I and type II IGF receptors (IGF-IR and IGF-IIR). Cell surface expression of IGF-IR, assessed by fluorescence-activated sorting, was lower in SH-EP cells than in SH-SY5Y cells. Immunoprecipitation of IGF-IR, followed by anti-phosphotyrosine or anti-IGF-IR immunoblotting, demonstrated functional expression of these receptors in both cell types and confirmed the lower level of IGF-IR expression in SH-EP cells. IGF-II promoted SH-EP cell growth in the presence of low concentrations of calf serum (0.1-0.3%) or 10 ng/ml epidermal growth factor (EGF). IGF-II stimulation of SH-EP growth was eliminated by the IGF-IR blocking antibody (alpha IR-3) but not by an IGF-IIR blocking antibody. Stimulation of cell growth via this receptor was also indicated by the ligand specificity for IGF analogs and insulin (IGF-II approximately IGF-I approximately des(1-3)IGF-I >> insulin). These results indicate that in the presence of a permissive factor such as calf serum or EGF, IGF-II stimulates SH-EP cell growth via the IGF-IR. Collectively, these data suggest that within primary neuroblastomas, IGF-II may act as a paracrine factor to contribute to the promotion of S cell growth.
Leventhal
P S
PS
Department of Neurology, University of Michigan, Ann Arbor 48109-0588, USA.
Randolph
A E
AE
Vesbit
T E
TE
Schenone
A
A
Windebank
A
A
Feldman
E L
EL
D001483:Base Sequence; D015152:Blotting, Northern; D002455:Cell Division / Q000502:physiology; D004815:Epidermal Growth Factor / Q000502:physiology; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D008969:Molecular Sequence Data; D009447:Neuroblastoma / Q000737:chemistry / Q000473:pathology; D010766:Phosphorylation; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000502:physiology; D017527:Receptor, IGF Type 2 / Q000235:genetics / Q000502:physiology; D014407:Tumor Cells, Cultured / Q000737:chemistry / Q000166:cytology / Q000648:ultrastructure; D014443:Tyrosine / Q000378:metabolism
D017527:Receptor, IGF Type 2; D014443:Tyrosine; D004815:Epidermal Growth Factor; D007335:Insulin-Like Growth Factor II; D017526:Receptor, IGF Type 1