Because of the critical role of neuroinflammation in various neurological diseases, there are continuous efforts to identify new therapeutic targets as well as new therapeutic agents to treat neuroinflammatory diseases. Here we report the discovery of inflachromene (ICM), a microglial inhibitor with anti-inflammatory effects. Using the convergent strategy of phenotypic screening with early stage target identification, we show that the direct binding target of ICM is the high mobility group box (HMGB) proteins. Mode-of-action studies demonstrate that ICM blocks the sequential processes of cytoplasmic localization and extracellular release of HMGBs by perturbing its post-translational modification. In addition, ICM effectively downregulates proinflammatory functions of HMGB and reduces neuronal damage in vivo. Our study reveals that ICM suppresses microglia-mediated inflammation and exerts a neuroprotective effect, demonstrating the therapeutic potential of ICM in neuroinflammatory diseases.

Blocking phosphorylation of peroxisome proliferator–activated receptor (PPAR)γ at Ser273 is one of the key mechanisms for antidiabetes drugs to target PPARγ. Using high-throughput phosphorylation screening, we here describe that Gleevec blocks cyclin-dependent kinase 5–mediated PPARγ phosphorylation devoid of classical agonism as a PPARγ antagonist ligand. In high fat–fed mice, Gleevec improved insulin sensitivity without causing severe side effects associated with other PPARγ-targeting drugs. Furthermore, Gleevec reduces lipogenic and gluconeogenic gene expression in liver and ameliorates inflammation in adipose tissues. Interestingly, Gleevec increases browning of white adipose tissue and energy expenditure. Taken together, the results indicate that Gleevec exhibits greater beneficial effects on both glucose/lipid metabolism and energy homeostasis by blocking PPARγ phosphorylation. These data illustrate that Gleevec could be a novel therapeutic agent for use in insulin resistance and type 2 diabetes.

Photoaffinity-based target identification has received recent attention as an efficient research tool for chemical biology and drug discovery. The major obstacle of photoaffinity-based target identification is the nonspecific interaction between target identification probes and nontarget proteins. Consequently, the rational design of photoaffinity linkers has been spotlighted for successful target identification. These nonspecific interactions have been considered as random events, and therefore no systematic investigation has been conducted regarding nonspecific interactions between proteins and photoaffinity linkers. Herein, we report the protein-labeling analysis of photoaffinity linkers containing three photoactivatable moieties: benzophenone, diazirine, and arylazide. Each photoaffinity linker binds to a different set of proteins in a structure-dependent manner, in contrast to the previous conception. The list of proteins labeled by each photoaffinity linker was successfully used to eliminate the nonspecific binding proteins from target candidates, thereby increasing the success rate of target identification.

MicroRNAs (miRNAs) regulate gene expression by targeting protein-coding transcripts that are involved in various cellular processes. Thus, miRNA biogenesis has been recognized as a novel therapeutic target. Especially, the let-7 miRNA family is well-known for its tumor suppressor functions and is downregulated in many cancer cells. Lin28 protein binds to let-7 miRNA precursors to inhibit their maturation. Herein, we developed a FRET-based, high-throughput screening system to identify small-molecule inhibitors of the Lin28-let-7 interaction. We employed unnatural amino acid mutagenesis and bioorthogonal chemistry for the site-specific fluorescent labeling of Lin28, which ensures the robustness and reliability of the FRET-based protein-miRNA binding assay. Using this direct binding assay, we identified an inhibitor of the oncogenic Lin28-let-7 interaction. The inhibitor enhanced the production of let-7 miRNAs in Lin28-expressing cancer cells and reduced the level of let-7 target oncogene products.

The inhibitory effect of curcumin and its synergism with 5-fluorouracil (5-FU) on the growth of the AGS human gastric carcinoma cell line was examined. Cell cycle analysis was used to elucidate the mechanisms for the inhibition by curcumin. Curcumin significantly inhibited the growth of AGS cells in a dose- and time-dependent manner (P <.05). Curcumin caused a 34% decrease in AGS proliferation at 5 micromol/L, 51% at 10 micromol/L, and 92% at 25 micromol/L after 4 days of treatment. When curcumin (10 micromol/L) was removed after a 24-hour exposure, the growth pattern of curcumin-treated AGS cells was similar to that of control cells, suggesting reversibility of curcumin on the growth of AGS cells. Combining curcumin with 5-FU significantly increased growth inhibition of AGS cells compared with either curcumin or 5-FU alone (P <.05), suggesting synergistic actions of the two drugs. After 4 days of treatment with 10 micromol/L of curcumin, the G2/M phase fraction of cells was 60.5% compared with 22.0% of the control group, suggesting a G2/M block by curcumin treatment. Because the curcumin concentrations (5 micromol/L) used in our study were similar to steady-state concentrations (1.77 +/- 1.87 micromol/L) in human serum of subjects receiving chronic administration of a commonly recommended dose (8 g/day), curcumin may be useful for the treatment of gastric carcinoma, especially in conjunction with 5-FU.