Human Homologue of Seta Binding Protein 1 Interacts with Cathepsin B and Participates in TNF-Induced Apoptosis in Ovarian Cancer Cells

Abstract

Lysosomal cysteine protease cathepsin B has been reported to play an important role in apoptosis of many different cancer cells, but the regulation of cathepsin B in apoptosis is poorly understood. Human homologue of SETA binding protein 1 (hSB1) was identified to interact with cathepsin B by yeast-two hybrid method, and the interaction was confirmed in vitro GST pull-down assay and in vivo coimmunoprecipitation experiment. hSB1 was co-localized with cathepsin B in cellular lysosomes. Our previous study has shown that TNF can induce ovarian cancer cells OV-90 apoptosis and the apoptosis process is cathepsin B-depended. Here we provide evidence that overexpression of cathepsin B-interacting protein hSB1 could suppress TNF-triggered apoptosis in OV-90 cells, but has no effect on cellular cathepsin B activity. hSB1 may function as a regulator of cathepsin B-mediated apoptosis.