PRODUCTION OF SULFATED PROTEOGLYCANS BY HUMAN BREAST-CANCER CELL-LINES - BINDING TO FIBROBLAST GROWTH FACTOR-II

The cellular distribution and nature of proteoglycans synthesised by h uman breast cancer cells in culture were studied. Proteoglycans were l abelled with [S-35] sulfate, purified, and characterised after ion-exc hange chromatography followed by gel-filtration chromatography and tre atment with glycosaminoglycan degrading enzymes. Proteoglycans were is olated from the culture medium and from cell layers of the hormono-dep endent well-differentiated MCF-7 cell line, the hormone-independent po orly-differentiate MDA-MB-231 and the HBL-100 cell line which is deriv ed from non malignant breast epithelium. HBL-100 and MDA-MB-231 cells produced larger amounts of proteoglycans which had a lower degree of s ulfation than MCF-7 cells. Cel-filtration chromatography on Sepharose CL-6B indicated that HBL-100 and MDA-ME-231 cells accumulated cell sur face heparan sulfate proteoglycans (HSPG), with a high apparent molecu lar weight (K-av 0.1). In contrast, the MCF-7 cell monolayers synthesi sed small sulfated macromolecules (K-av 0.4) which possessed mostly ch ondroitin sulfate chains. Moreover, considerable differences in the na ture of the sulfated proteoglycans released into the culture medium of these breast epithelial cell lines were observed. MCF-7 cells release d into the culture medium HSPG as the main proteoglycan component whil e MDA-MB-231 and HBL-100 cells released mainly chondroitin sulfate pro teoglycans. In these three cell lines, medium-released sulfated macrom olecules have a higher hydrodynamic size than cell-associated ones. Pr oteoglycans purified by ion-exchange chromatography were tested for th eir ability to bind I-125 FGF-2. We demonstrated that HBL-100 and MDA- MB-231 cells bind more FGF-2 to their heparan sulfate proteoglycans th an MCF-7 cells. Taken together, these results suggest that differences in proteoglycan synthesis of human breast epithelial cells could be r esponsible for differences in their proliferative and/or invasive prop erties. (C) 1997 Wiley-Liss, Inc.