MITOGENIC ACTIVITY OF PROCATHEPSIN-D PURIFIED FROM CONDITIONED MEDIUMOF BREAST-CANCER CELLS BY AFFINITY-CHROMATOGRAPHY ON PEPSTATINYL AGAROSE

A simple procedure for the affinity purification of procathepsin D fro m tissue culture medium conditioned by breast-cancer cells is describe d. This procedure yielded 2 mu g of procathepsin D/100 ml medium. The procathepsin D was approximately 95% pure as judged by silver staining of polyacrylamide gels, the major contaminant being mature cathepsin D. The ability of procapthesin D to stimulate the proliferation of oes trogen-responsive MCF-7 breast cancer cells was determined. The purifi ed procapthesin D had no mitogenic effect alone or in combination with oestradiol or other growth factors. These data suggest that procapthe sin D does not act as an oestrogen-regulated autocrine growth factor f or malignant breast epithelial calls. (C) 1994 Wiley-Liss, Inc.