ANTISENSE EPIDERMAL GROWTH-FACTOR RECEPTOR TRANSFECTION IMPAIRS THE PROLIFERATIVE ABILITY OF HUMAN RHABDOMYOSARCOMA CELLS

Human rhabdomyosarcoma cells express membrane epidermal growth factor receptor (EGF-R), which could confer responsiveness to EGF and transfo rming growth factor-alpha (TGF-alpha) of autocrine or paracrine origin . To study the role played by this growth factor circuit in the prolif eration and differentiation of myogenic neoplastic cells, human rhabdo myosarcoma EGF-R-expressing cells (RD/18 clone) have been transfected with a plasmid containing a fragment of the EGF-R cDNA in the antisens e orientation, In vitro growth and differentiative ability were studie d on six antisense-transfected clones (AS) in comparison to parental R D/18 cells and to cells transfected with the plasmid containing only t he neomycin resistance gene (NEO). A reduced EGF-R membrane expression was found in AS clones by decreased immunofluorescence with an anti-E GF-R monoclonal antibody. All AS transfectants had a greatly impaired proliferative ability, even when cultured in fetal bovine serum-contai ning medium, Proliferation of AS clones was completely blocked in medi um supplemented with 2% horse serum. The differentiation ability of AS clones was heterogeneous, ranging from clones with a percentage of my osin-positive cells higher than controls to clones with a negligible m yosin expression. Therefore, the growth impairment determined by the l oop interruption is not sufficient to snitch on the differentiation pr ogram. The role played by EGF-R in the proliferation of human rhabdomy osarcoma cells suggests that this receptor could constitute a target f or a therapeutic approach.