Fig. 2

HDS interacted with RRM2 and inhibited RNR activity.  A T1ρ spectra acquired by using 200 µM HDS solely (colored in red) and 200 µM HDS in the presence of 5 µM RRM2 protein (colored in green) are presented. B STD spectrum acquired by using 200 µM HDS in the presence of 5 µM RRM2 protein (colored in red) is presented. C SPR biosensor was used to detect the binding of HDS to RRM2. Representative sensorgrams of the interaction of 0.78125 to 100.0 µM HDS with 200 µg/mL RRM2. D Cellular thermal shift assay to examine interactions of compounds (100 µM HDS, 0.5 µM gemcitabine, or 500 µM HU) with RRM1 and RRM2. Lower panel is the charts of percentages of non-denatured protein fraction. E MM cells were treated with HDS for 24 h. Then the intracellular RNR was extracted and measured by LC–MS/MS system. F MM cells were treated with HDS (0, 50, and 100 µM) for 24 h. Then the intracellular dNTPs were extracted and measured. Data are presented as the means ± SD of 3 independent experiments. **P < 0.01, ***P < 0.001