Differentiation of BA-HAN-1C rhabdomyosarcoma cells is controlled by a pertussis toxin sensitive signaling pathway

BA-Han-1C rat rhabdomyosarcoma cells grow with a transformed phenotype and do not differentiate efficiently. Here, we report that these cells can be induced with pertussis toxin (PTX) to rapidly express the myogenin gene and form terminally differentiated myotubes. Potential targets for the effect mediated by PTX are G alpha i-2 and G alpha i-3 proteins, the only inhibitor GTP-binding proteins expressed in these cells. While G alpha i-2 is found at the plasma membrane, G alpha i-3 is predominantly associated with Golgi vesicles and endoplasmic reticulum, suggesting that it may regulate protein trafficking. Differentiation of BA-Han-1C cells can also be induced by suramin, heparin, and other polyanions. As these compounds bind certain peptide growth factors, we assume that differentiation of BA-Han-1C cells is blocked by pathways involving autocrine or paracrine acting growth stimulating peptides. We present evidence that bFGF and cAMP inhibit induced differentiation in BA-Han-1C cells similar to normal myogenic cell lines, suggesting that signaling pathways mediated by these compounds are unaltered.