INSERM U540 'Endocrinologie Moléculaire et Cellulaire des Cancers', Université de Montpellier 1, 60 rue de Navacelles, 34090 Montpellier, France

Correspondence to: M Garcia, E-mail: garcia@u540.montp.inserm.fr

Overexpression of cathepsin-D in primary breast cancer has been associated with rapid development of clinical metastasis. To investigate the role of this protease in breast cancer growth and progression to metastasis, we stably transfected a highly metastatic human breast cancer cell line, MDA-MB-231, with a plasmid containing either the full-length cDNA for cathepsin-D or a 535 bp antisense cathepsin-D cDNA fragment. Clones expressing antisense cathepsin-D cDNA that exhibited a 70-80% reduction in cathepsin-D protein, both intra- and extracellularly compared to controls, were selected for further experiments. These antisense-transfected cells displayed a reduced outgrowth rate when embedded in a Matrigel matrix, formed smaller colonies in soft agar and presented a significantly decreased tumor growth and experimental lung metastasis in nude mice compared with controls. However, manipulating the cathepsin-D level in the antisense cells has no effect on their in vitro invasiveness. These studies demonstrate that cathepsin-D enhances anchorage-independent cell proliferation and subsequently facilitates tumorigenesis and metastasis of breast cancer cells. Our overall results provide the first evidence on the essential role of cathepsin-D in breast cancer, and support the development of a new cathepsin-D-targeted therapy.

Oncogene (2002) 21, 5127-5134. doi:10.1038/sj.onc.1205657

cathepsin-D; antisense RNA; breast cancer; growth; metastasis