DIFFERENTIAL MIGRATORY RESPONSE OF U-2 OS OSTEOSARCOMA CELL TO THE VARIOUS FORMS OF PLATELET-DERIVED GROWTH-FACTOR

U-2 OS osteosarcoma cells are mesenchymal-derived transformed cells sp ontaneously expressing both platelet-derived growth factor (PDGF) A- a nd B-chain genes, and releasing PDGF AA dimers in culture. Using modif ied Boyden chemotactic chambers, platelet-purified PDGF was shown to b e a chemoattractant for U-2 OS cells. More specifically, U-2 OS cells migrated in the presence of PDGF AB and BB dimers but not in the prese nce of PDGF AA dimers. This pattern of response was similar to that ob served with human fibroblasts and this similarity is consistent with t he fact that U-2 OS cells express PDGF receptor-alpha- and beta-subuni ts in a similar fashion to human fibroblasts.