C0818, a novel curcumin derivative, interacts with Hsp90 and inhibits Hsp90 ATPase activity

The aims of the present study were to estimate the affinity between 3,5-()-bis(3-methoxy-4-hydroxybenzal)-4-piperidinone hydrochloride (C0818) and heat shock protein 90 (Hsp90) and to investigate the inhibitory effects of this compound on Hsp90 ATPase activity. Fluorescence spectroscopy was used to examine the affinity between varying concentrations of C0818 and Hsp90, N-Hsp90, M-Hsp90 and C-Hsp90. Fluorescence intensities were recorded in the range of 290-510 nm at 293, 303 and 310 K, respectively. A colorimetric assay for inorganic phosphate (based on the formation of a phosphomolybdate complex and the subsequent reaction with malachite green) were used to examine the inhibitory effects of C0818 on Hsp90 ATPase activity. The equilibrium dissociation constantvalue of C0818 was found to be 23.412±0.943 μmol/L. The interaction between C0818 and Hsp90 was driven mainly by electrostatic interactions. C0818 showed the strongest affinity with C-Hsp90. These results conclusively demonstrate the inhibitory activity of C0818 on the activity of Hsp90 ATPase.

BMS-345541 regulates repair of DNA double-strand breaks induced by VP-16 in acute myeloid leukemia cells / 中国药理学通报

Aim To investigate the effect of BMS- 345541 on the repair of DNA DSBs induced by VP-16 in AML cells and its possible mechanism. Methods The effects of BMS-345541 on the sensitivity of AML cells to VP-16 were determined by MTT. Flow cytome-try ( FCM) was applied to test the level of DNA dam-age, cell cycle progression and apoptosis in AML cells. High content analysis ( HCA) was used to verify the amount ofγ-H2AX,p-ATM,RAD51 in AML cells. Results BMS-345541 could significantly inhibit the proliferation of AML cells induced by VP-16 . BMS- ＜br> 345541 increased the amount of RAD51 foci and p-ATM foci in AML cells treated with VP-16 after 6 hours , which led to increased numbers of cells in the G2/M phases of the cell cycle,then induced apoptotic cell death. Conclusion BMS-345541 sensitizes AML cells to VP-16 via selective inhibition of homologous recombinational repair of DNA double-strand breaks.

Interactions between curcumin derivatives C085 and various constructs of Hsp90 and effects of C085 on Hsp90 ATPase activity / 中国药理学通报

Aim To estimate the affinity between C085 and Hsp90 and the inhibitory effects of C085 on the activity of Hsp90 ATPase. Methods The fluores-cence spectrum experiment was applied to examine the affinity between different C085 concentrations and Hsp90 , NHsp90 , MHsp90 , CHsp90; fluorescence in-tensities were recorded in the range of 290-510 nm at 293 K, 303 K and 310 K, respectively;a colorimetric assay for inorganic phosphate based on the formation of a phosphomolybdate complex and subsequent reaction with malachite green was used to examine the inhibitory effects of C085 on the activity of Hsp90 ATPase. Re-sults The dissociation constant KD value of C085 was (11. 163 ± 0. 316 ) μmol · L-1 . The interaction be-tween C085 and Hsp90 was driven mainly by electro-static interaction. C085 showed strongest affinity with CHsp90. When the concentration of ATP was 1 mmol· L-1 ,the inhibition of Hsp90 ATPase activity of C085 with the IC50 value was 6. 04μmol·L-1 . Conclusions The interaction mechanism between C085 and Hsp90 can be analyzed by fluorescence spectrum. C085 shows strong inhibition ATPase activity of Hsp90 .