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Fig. 6 | Cell Communication and Signaling

Fig. 6

From: Curcumin derivative C212 inhibits Hsp90 and eliminates both growing and quiescent leukemia cells in deep dormancy

Fig. 6

C212 decreases Hsp90 client protein levels and induces protein aggregates. a Concentration-dependent quenching effect of C212 (0–50 μM) on the intrinsic fluorescence of N-, M-, and C-domains of Hsp90. Y- and X-axis indicate fluorescence intensity and emission wavelength, respectively. Each curve represents the average of triplicate measurements. b Leukemia cells (HL60, left; K562, right) were treated with C212 at the indicated doses for 24 h, followed by Western blot of Hsp90 client proteins in cell lysates. c HL60 (top) and K562 (bottom) cells that were serum-starved as in Fig. 4 a and b to induce quiescence/slow-growth were further treated with C212 at the indicated doses for 30 and 36 h, respectively, then subjected to fluorescence-based protein aggregation assay using ProteoStat. Error bar, SEM (n = 2); *p < 0.05, ** p < 0.01 (over control at 0 μM).d Quiescent HL60 (top) and K562 (bottom) cells were treated with C212 at the indicated doses for 30 and 36 h, respectively, in the presence or absence of 12 μM CQ, then subjected to fluorescence-based protein aggregation assay using ProteoStat. Error bar, SEM (n = 2); *p < 0.05, ** p < 0.01, *** p < 0.001. e HL60 (left) and K562 (right) cells were serum-starved, treated with C212 at the indicated doses in the presence or absence of CQ, and serum-stimulated as in Fig. 5 a and b, respectively. Cells were then harvested and subjected to Click-iT EdU assay. f A proposed model of C212 to deepen quiescence of leukemia cells by inhibiting Hsp90 and inducing protein aggregates, and thus increasing the serum threshold for quiescence exit

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