Cathepsin L is involved in proliferation and invasion of breast cancer cells.

Cathepsin L(CTSL), a lysosomal endopeptidase was found overexpressed in Breast cancer (BC). The purpose of this work was to investigate the possible role of CTSL in the development of BC. RNA interference(RNAi) with a CTSL small hairpin RNAs(CTSL-shRNA) and plasmid with CTSL were used to identify the effects of CTSL on malignant behaviors of BC. MCF-7 and SKBR-3 were selected as cell models in vitro and in vivo. The results showed that down-regulation of CTSL can significantly inhibit the proliferative and invasive ability of MCF-7 cell, while up-regulation of CTSL in SKBR-3 cells had opposite effects. Comparing to parental BC cells, CTSL knockdown cells exhibited attenuated capacities in developing tumor in nude mice, furthermore, the growth of these xenografts were dramatically regressed. In conclusion, our findings suggest that CTSL contributes to the proliferation and metastasis of BC and might be a potent molecular target for BC treatment.