Background to bone metastasis programme

Primary breast cancer cells, metastatic breast cancer cells and in vitro cultured breast cancer cells have all been shown to produce significant amounts of cathepsin K (Littlewood-Evans, et al., (1997)); cathepsin K expression has also been reported to be an indicator of metastasis (Husmann, et al., (2008)).  Inhibition of cathepsin K reduces breast cancer-induced osteolysis and skeletal tumour burden (Le Gall, et al., (2007).

Cathepsin K is the key cysteine peptidase produced by bone degrading cells (i.e. osteoclasts) and catalyses the proteolysis of type I collagen.  This results in a weakening of the bone matrix eventually leading to bone degradation, fragility and skeletal damage.  Inhibition of cathepsin K activity may provide a novel treatment for bone metastasis.