Expression of HER/erbB family of receptor tyrosine kinases and induction of differentiation by glial growth factor 2 in human rhabdomyosarcoma cells.

Five human rhabdomyosarcoma cell lines were used to investigate the surface expression of HER/erbB receptors, particularly of HER-2, HER-3 and HER-4, by flow cytometry. HER-2 was expressed in 3/5 rhabdomyosarcoma cell lines. HER-3 was expressed in all rhabdomyosarcoma cell lines. None of the rhabdomyosarcoma cell lines investigated showed HER-4 surface expression. To study the biological activity of HER/erbB receptors in rhabdomyosarcomas, cells were cultured in the presence of glial growth factor 2 (GGF-2), a specific ligand of HER-3 that is able to stimulate myogenesis in normal myoblasts. In 3 of 3 human rhabdomyosarcoma cell lines positive for both HER-2 and HER-3 receptors, the treatment with GGF-2 induced a significant increase in myogenic differentiation.