Fig. 1

Cytotoxic activity of HDS against MM cells.  A Indicated MM cell lines were treated with vehicle or HDS (12.5, 25, 50, 100, 200, 300, 400 µM) for 72 h. Then the cell viability was determined by CCK-8 assay. Cell viability data are presented as the means of 3 independent experiments in a Heatmap. B Cell clone colonies formed by the H929 and ARP-1 cells treated with HDS (0, 50 and 100 µM); the colonies in each well were quantified. C Primary CD138⁺ MM cells from patients (Pt#1–Pt#9) and normal PBMCs from healthy donors (D#1–D#3) were exposed to HDS with the indicated concentrations for 72 h and then apoptosis was analyzed. Pt represents patient. D represents healthy donor. D H929 cells were treated with indicated concentrations of HDS alone or in the presence of IL-6 or IGF-1 for 72 h. Cell viability was determined by CCK-8 assay. E H929 cells treated with different concentrations of HDS (0, 50 and 100 µM) were cultured with or without BMSCs for 72 h, and cell growth was assessed using CCK-8 assay. F H929 cells were exposed to 0, 50 and 100 µM HDS for indicated time (24, 48 and 72 h). Cell apoptosis was determined by Annexin V/PI staining. Representative results of triplicate experiments were shown. G Representative fluorescent images of typical apoptotic cells evaluated by TUNEL staining (red) after 100 µM HDS treatment for 24 h. DAPI was used as a nuclear stain (blue). H Cell cycle analysis was performed using flow cytometry. Percentages showed cell population in S-phase. I The viability of H929 and ARP-1 cells transfected with scramble or corresponding shRNA plasmids with HDS treatment (0, 12.5, 25, 50, 100 and 200 µM, 72 h) were analyzed by a CCK-8 assay. Western blots showed RRM1 and RRM2 expressions in H929 and ARP-1 cells after transfected with RRM1 or RRM2 shRNA. Notably, the cell viability of RRM1-shRNA transfected cells and scramble-transfected cells were not significantly different at the corresponding HDS concentration. J CCK-8 assay was performed on RRM1-OE and RRM2-OE cells or empty vector-transfected cells. Western blots showed RRM1 and RRM2 overexpression in H929 and ARP-1 cells after transfected with RRM1 OE or RRM2 OE vectors. Empty vector-transfected cells served as controls. Data are presented as the means ± SD of 3 independent experiments. *P < 0.05; **P < 0.01; #, not significant