ANTISENSE EPIDERMAL GROWTH-FACTOR RECEPTOR RNA TRANSFECTION IN HUMAN-MALIGNANT GLIOMA-CELLS LEADS TO INHIBITION OF PROLIFERATION AND INDUCTION OF DIFFERENTIATION

The epidermal growth factor receptor (EGFR) is a protooncogene that is frequently observed with alterations in late stage gliomas, suggestin g an important role of this gene in glial tumorigenesis and progressio n. In this study we evaluated an antisense EGFR approach as an alterna tive therapeutic modality for glioblastomas. We transfected U-87MG cel ls with an antisense EGFR construct and obtained several clones stably expressing lower or undetectable levels of EGFR protein. These clones were found to have impaired proliferation as well as a reduced transf orming potential to grow in soft agarose. The number of cells positive for the cell cycle-specific nuclear antigen Ki-67 was also significan tly decreased (P < 0.05) in antisense EGFR-transfected clones compared with parental or empty vector-transfected cells. Flow cytometric anal ysis revealed that the proportion of cells in G(0)/G(1) phases of the cell cycle in the antisense clones increased by up to 31% compared wit h control cells, whereas the proportion of cells in S phase decreased by up to 58%. In addition, the antisense EGFR-transfected cells showed higher expression of glial fibrillary acidic protein and a more diffe rentiated form, with smaller cell bodies possessing fine tapering cell processes. These results suggest that EGFR plays a major role in modu lating cell growth and differentiation in glioblastoma cells. Our expe rimental model of antisense EGFR provides a basis for future developme nt of antisense EGFR oligodeoxynucleotides in treatment of glioblastom as.