Background and Purpose Aberrant lipid metabolism is recognized as a key feature of cancer cells. Our initial research on MS‐based analysis of lipids in a multiple myeloma (MM) cell line showed a significant accumulation of lipids in multiple myeloma cells after proteasome inhibition. This finding prompted us to hypothesize that multiple myeloma cell survival depends on the maximal utilization of abnormally accumulated lipids. Therefore, we explored whether lipid metabolism‐modulating agents would synergize with proteasome inhibitors. Experimental Approach Lipid accumulation in multiple myeloma cells was measured by MS. Synergism between lipid regulators and proteasome inhibitors was assessed by cell viability and apoptosis. A novel stable derivative of fenofibrate (FCE) was synthesized and used to treat multiple myeloma cells in vitro and in vivo along with the proteasome inhibitor ixazomib. ChIP‐seq, western blotting and RT‐qPCR were performed to explore the potential mechanism(s) underlying the increase in lipid levels in multiple myeloma cells after proteasome inhibition. Key Results Accumulation of lipids in multiple myeloma cells was induced by proteasome inhibition. Lipid‐lowering drugs and MG‐132 exerted a synergistic effect to kill multiple myeloma cells. FCE showed significant synergistic activity in vitro and in vivo with ixazomib. The abnormal lipid accumulation in multiple myeloma cells that was enhanced by proteasome inhibitors might be due to the elevated SREBP1/2 expression induced by ATF4. Conclusions and Implications Our results provide a proof of principle and support for the further clinical evaluation of the combination of lipid‐modulating drugs with proteasome inhibitors in the treatment of multiple myeloma.

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BackgroundNGF-TrkA is well known to play a key role in propagating and sustaining pruritogenic signals, which form the pathology of chronic pruritus. Inhibition of NGF-TrkA is a known strategy for the treatment of pruritus. In the present paper, we describe the identification, in vitro characterization, structure–activity analysis, and inhibitory evaluation of a novel TrkA inhibitory scaffold exemplified by Cucurbitacins (Cus).MethodsCus were identified as TrkA inhibitors in a large-scale kinase library screen. To obtain structural models of Cus as TrkA inhibitors, AutoDock was used to explore their binding to TrkA. Furthermore, PC12 cell culture systems have been used to study the effects of Cus and traditional Chinese medicinal plants (Tian Gua Di and bitter gourd leaf) extracts on the kinase activity of TrkA.ResultsCus block the phosphorylation of TrkA on several tyrosine sites, including Tyr490, Tyr674/675, and Tyr785, and inhibit downstream Akt and MAPK phosphorylation in response to NGF in PC12 cell model systems. Furthermore, traditional Chinese medicinal plants (Tian Gua Di and bitter gourd leaf) containing Cu extracts were shown to inhibit the phosphorylation of TrkA and Akt. These data reveal mechanisms, at least partly, of the anti-pruritus bioactivity of Cus.ConclusionTaken together, with the recent discovery of the important role of TrkA as a therapeutic target, Cus could be the basis for the design of improved TrkA kinase inhibitors, which could someday help treat pruritus.

Anethol trithione (ATT) has a wide range of physiological activities, but its use is limited due to its poor water solubility. To improve the solubility of ATT, we synthesized and characterized a novel phosphate prodrug (ATXP) relying on the availability of the hydroxy group in 5-(4-hydroxyphenyl)-3H-1,2-dithiole3-thione (ATX), which was transformed from ATT rapidly and extensively in vivo. Our results showed that ATXP significantly improved drug solubility. ATXP was rapidly converted to ATX and reached a maximum plasma concentration with a T max of approximately 5 min after intravenous (iv) administration. Furthermore, after the oral administration of ATXP, the C max was 3326.30 ± 566.50 ng/mL, which was approximately 5-fold greater than that of the parent drug form, indicating that ATXP has greater absorption than that of ATT. Additionally, the oral phosphate prodrug ATXP increased the ATX in the area under the plasma concentration vs time curves (AUC 0−t = 3927.40 ± 321.50 and AUC 0−∞ = 4579.0 ± 756.30), making its use in practical applications more meaningful. Finally, compared to the vehicle, ATXP was confirmed to maintain the bioactivity of the parent drug for a significant reduction in infarct volume 24 h after reperfusion. Based on these findings, the phosphate prodrug ATXP is a potentially useful water-soluble prodrug with improved pharmacokinetic properties.