Preferential down-regulation of phospholipase C-β in Ewing's sarcoma cells transfected with antisense EWS-Fli-1

EWS-Fli-1, a fusion gene found in Ewing's sarcoma and primitive neuro-ectodermal tumour (PNET), encodes a transcriptional activator and promotes cellular transformation. We have made stable Ewing's sarcoma cells expressing antisense EWS-Fli-1 transcripts by transfecting the antisense EWS-Fli-1 expression plasmid. These cells showed partial loss of endogenous EWS-Fli-1 proteins and suppression of the cell growth. To elucidate the molecular mechanisms underlying the growth inhibition, we examined the changes of signal transducing proteins by immunoblot analysis in Ewing's sarcoma cells stably expressing antisense EWS-Fli-1 transcripts. Western blotting of the cell proteins revealed that expressions of phospholipase C beta 2 and beta 3 (PLC beta 2, PLC beta 3), and also protein kinase C alpha and beta (PKC alpha, beta) were significantly reduced by transfecting with antisense EWS-Fli-1. The inositol phosphates production by bradykinin (BK), but not platelet-derived growth factor (PDGF), was suppressed in these cells. These results suggest that the PLC beta 2 and PLC beta 3 may play a role in tumour proliferation in Ewing's sarcoma cells. (C) 2000 Cancer Research Campaign.