Combined magnetic fields increase insulin-like growth factor-II in TE-85 human osteosarcoma bone cell cultures.
In vitro exposure to low-energy, combined magnetic fields (CMF) increased the release of insulin-like growth factor (IGF)-II from human TE-85 osteosarcoma cells. Short-term CMF exposure of only 10 min increased IGF-II levels in conditioned medium 1 h post CMF exposure. IGF-II levels were measured with a radioreceptor assay using H-35 cells that contain abundant IGF-II but not IGF-I receptors. This assay also uses a recently validated BioGel P-10 acid gel filtration method to remove IGF binding protein before quantitation of either IGF-I or IGF-II. In addition to an increase in IGF-II levels, DNA synthesis, as an index of cell proliferation, was increased during the 24-h period post CMF exposure. A monoclonal antibody against IGF-II blocked the increase in cell proliferation following CMF exposure, whereas a control monoclonal antibody against osteocalcin did not attenuate the mitogenic action of CMF exposure. The effect of CMF exposure to increase both cell proliferation and IGF-II was cell-density dependent with greater stimulation by CMF observed at lower densities. Together, these data are consistent with the hypothesis that CMF exposure stimulates release/production of IGF-II from bone cells and that increased IGF-II then promotes an increase in cell proliferation.
Fitzsimmons
R J
RJ
Department of Medicine, Loma Linda University, Jerry L. Pettis VA Hospital, California 92354, USA.
Ryaby
J T
JT
Mohan
S
S
Magee
F P
FP
Baylink
D J
DJ
D002452:Cell Count; D017077:Culture Media, Conditioned; D004247:DNA / Q000096:biosynthesis; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000494:pharmacology; D007335:Insulin-Like Growth Factor II / Q000378:metabolism* / Q000494:pharmacology; D008280:Magnetics; D012516:Osteosarcoma / Q000378:metabolism*; D011869:Radioligand Assay; D014407:Tumor Cells, Cultured
D017077:Culture Media, Conditioned; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D004247:DNA