GENE THERAPEUTIC APPROACHES TO PRIMARY AND METASTATIC BRAIN-TUMORS .2. RIBOZYME-MEDIATED SUPPRESSION OF CD44 EXPRESSION

Glioblastomas are highly invasive intracerebral tumors that are known to express the CD44 cell adhesion molecule. Human glioma cell adhesion and invasion in vitro may in part be mediated by the interaction of C D44 with extracellular matrix proteins. To suppress the growth and inv asive effects of CD44 expression on primary brain tumors we have desig ned two hammerhead ribozymes as potential gene therapeutic agents. Bot h ribozymes designed to target exon 2 of CD44 exhibited in vitro cleav age of in vitro transcribed CD44s and CD44R1 RNAs. The anti-CD44 effec t of these ribozymes results from directed RNA cleavage, requiring bot h a target sequence and an appropriate catalytic center. Further, foll owing transient transfection of one of these ribozymes into the SNB-19 glioma cell line, significant in vivo cleavage activity against cellu lar CD44 transcripts was demonstrated by flow cytometrical analysis. T hese preliminary results suggest that CD44-directed hammerhead ribozym es may be useful as gene therapeutic agents.