Down-regulation of cathepsin B expression impairs the invasive and tumorigenic potential of human glioblastoma cells

Increases in abundance of cathepsin B transcript and protein correlate with increases in tumor grade and alterations in subcellular localization and a ctivity of cathepsin B, The enzyme is able to degrade the components of the extracellular matrix (ECM) and activate other proteases capable of degradi ng ECM, To investigate the role played by this protease in the invasion of brain tumor cells, we transfected SNB19 human glioblastoma cells with a pla smid containing cathepsin B cDNA in antisense orientation. Control cells we re transfected with vector alone. Clones expressing antisense cathepsin B c DNA exhibited significant reductions in cathepsin B mRNA, enzyme activity a nd protein compared to controls. Matrigel Invasion assay showed that the an tisense-transfected cells had markedly diminished invasiveness compared wit h controls. When tumor spheroids containing antisense transfected SNB19 cel ls expressing reduced cathepsin B were co-cultured with fetal rat brain agg regates, invasion of fetal rat brain aggregates was significantly reduced. Green Fluorescent Protein (GFP) expressing parental cells and antisense tra nsfectants were generated for detection in mouse brain tissue without any p ost-chemical treatment. Intracerebral injection of SNB19 stable antisense t ransfectants resulted in reduced tumor formation in nude mice. These result s strongly support a role for cathepsin B in the invasiveness of human glio blastoma cells and suggest cathepsin B antisense may prove useful in cancer therapy.