Expression of HSPGs and syndecan-1 on MM cells.

(A) Expression of HS on the MM cells. Cell lines XG-1 and LME-1 and primary myeloma (PM) cells were stained with a mouse anti-HS antibody (10E4; solid line), or isotype control (dashed line), followed by R-phycoerythrin–conjugated goat antimouse and analyzed by FACS. (B) Expression of the HSPG core protein syndecan-1 by XG-1 and LME-1 cell lines and by PM cells. Cells were stained with a mouse anti–syndecan-1 antibody (B-B4; solid line) or isotype control (dashed line), and expression was analyzed by FACS. The syndecan-1 stably transfected cell line Namalwa (Nam^SYN) was used as a positive control. (C) XG-1, LME-1, and PM cells express a single HSPG of approximately 90 kd that represents syndecan-1. (Left panel) HSPG expression was detected with mAb 3G10 against desaturated uronate (ΔHS stubs) of HS. To allow detection of the ΔHS stubs, the cells were treated with heparitinase before immunoblotting. Namalwa cell lines, either wild type (Nam) or stably transfected with syndecan-1 (Nam^SYN) or glypican-1 (Nam^GLYP), were used as negative and positive controls for HSPG and syndecan-1 expression. (Right panel) After stripping, the same blot was restained with mAb B-B4 against syndecan-1.