ISOLATION OF A CDNA FOR A GROWTH-FACTOR OF VASCULAR ENDOTHELIAL-CELLSFROM HUMAN LUNG-CANCER CELLS - ITS IDENTITY WITH INSULIN-LIKE GROWTH FACTOR-II

We have found growth-promoting activity for vascular endothelial cells in the conditioned medium of a human lung cancer cell line, T3M-11. P urification and characterization of the growth-promoting activity have been carried out using ammonium sulfate precipitation and gel-exclusi on chromatography. The activity migrated as a single peak just after r ibonuclease. It did not bind to a heparin affinity column. These resul ts suggest that the activity is not a heparin-binding growth factor (i ncluding fibroblast growth factors) or a vascular endothelial growth f actor. To identify the molecule exhibiting the growth-promoting activi ty, a cDNA encoding the growth factor was isolated through functional expression cloning in COS-1 cells from a cDNA library prepared from T3 M-11 cells. The nucleotide sequence encoded by the cDNA proved to be i dentical with that of insulin-like growth factor II.