Syndecan-1 gene mRNA and soluble syndecan-1 are down-regulated in HPSE-silenced cells. U266 cells were electroporated with no siRNA or with a nontargeting control siRNA (siRNA-co) or with an HPSE-specific siRNA (siRNA-HPSE) and cultured for 2 days. (A) At day 2, HPSE, syndecan-1 gene, and GAPDH expression were quantified by real-time RT-PCR and were normalized for each sample to that of B2M. Cells electroporated with no siRNA were used as a reference and were assigned the arbitrary value of 100. Data are means ± SD of the gene expression levels determined for 5 independent experiments.*Mean value is statistically significantly from that obtained with the control (no siRNA), using a Student t test for pairs (P ≤ .05). (B) Membrane expression of syndecan-1 was determined with a PE-conjugated anti-CD138 MoAb and a PE-isotype–matched control MoAb and FACS analysis. Results shown are those of 1 experiment representative of 5. (C) U266 cells were electroporated with no siRNA or with a nontargeting control siRNA (siRNA-co) or with siRNA-HPSE. Data are expressed as the means ± SD of the rates of production of soluble syndecan-1 per 106 cells and per 24 hours determined during the first and second days of culture after electroporation determined in 5 separate experiments. *Mean value is statistically significantly different from that obtained in the control (no siRNA), using a Student t test for pairs (P ≤ .05).
