Syndecan-1 and stromal heparan sulfate proteoglycans: key moderators of plasma cell biology and myeloma pathogenesis.

Plasma cells no longer express a B-cell-antigen-receptor and are hence deprived of signals crucial for survival throughout B-cell development. Instead, normal plasma cells, as well as their malignant myeloma counterparts, heavily rely on communication with the bone-marrow (BM) microenvironment for survival. The plasma cell heparan-sulfate-proteoglycan (HSPG) syndecan-1 (CD138), and HSPGs in the BM-microenvironment, acts as master regulator of this communication by co-opting specific growth- and survival-factors from the BM-niche. This designates syndecan-1/HSPGs, and their synthesis-machinery, as potential treatment targets in MM.