Suppression of glioblastoma cell growth following antisense oligonucleotide-mediated inhibition of fibroblast growth factor receptor expression

Astrocytes exhibit significant changes in fibroblast growth factor receptor (FGFR) gene expression during malignant progression. These changes include induction of FGFR1 and concomitant loss of FGFR2 expression. The induction of FGFR1 is believed to endow malignant astrocytes with a selective growth advantage. Glioblastoma (the most malignant form of astrocytoma) cell line s, which exhibit the same pattern of FGFR gene expression as glioblastoma b iopsies, were used to evaluate the contribution of FGFR1 expression to glio blastoma cell growth. Addition of phosphorothioate-modified antisense oligo nucleotides complementary to the initiation site or the alpha exon of the F GFR1 gene suppressed growth of human glioblastoma-derived cell lines. Rever se antisense controls or antisense oligonucleotide complementary to FGFR2 h ad no effect on proliferation. Consistent with its growth-suppressive effec t, FGFR1 antisense oligonucleotides markedly reduced expression of both FGF R1 mRNA ana high-affinity bFGF binding sites, whereas FGFR1 reverse antisen se control oligonucleotide had no effect. Antisense oligonucleotide targete d to the or exon of the FGFR1 gene suppressed alpha and beta alternatively spliced FGFR1 mRNA isoforms but did not alter the expression of related FGF R family members. Fluorescein-labeled antisense and reverse control oligonu cleotides demonstrated cellular uptake and nuclear accumulation. These resu lts indicate that alterations in FGFR expression may contribute to malignan t proliferation in human astrocytomas. These findings also illustrate the h igh degree of selectivity that can be obtained with antisense oligonucleoti des, a property that is essential for employing these reagents therapeutica lly. (C) 1999 Wiley-Liss, Inc.