Cathepsin L Affects Apoptosis of Glioblastoma Cells: a Potential Implication in the Design of Cancer Therapeutics

Abstract

Background: Previous studies indicate that Cathepsin L (CatL) is involved in brain tumour progression. Here, CatL in tumour cell invasion and apoptosis has been studied. Materials and Methods: Human glioblastoma cell line U87 was transfected with CatL cDNA in sense and antisense orientations. The in vitro invasiveness was tested in modified Boyden chambers. Apoptosis was determined by fluorescent staining, caspase activity, and by Bax and Bcl-2 mRNA levels. Results: Surprisingly, the invasiveness of U87 cells was not impaired by genetic down-regulation of CatL expression. In the CatL antisense clones, the apoptotic rate induced by either intrinsic or extrinsic stimuli was increased, whereas CatL sense transfection seemed to protect the cells from apoptosis. Conclusion: Increased chemoresistance of tumour cells may be associated with increased levels of CatL and may have potential application in gene therapy, which would augment the apoptosis of glioblastoma cells induced by chemotherapy.