New developments in detection technologies are providing a variety of biomolecular screening strategies from which to choose. Consequently, we performed a detailed analysis of both separation-based and non-separation-based formats for screening nuclear receptor ligands. In this study, time-resolved fluorescence resonance energy transfer (TR-FRET), ALPHAScreen, and time-resolved fluorescence (TRF) assays were optimized and compared with respect to sensitivity, reproducibility, and miniaturization capability. The results showed that the ALPHAScreen system had the best sensitivity and dynamic range. The TRF assay was more time consuming because of the number of wash steps necessary. The TR-FRET assay had less interwell variation, most likely because of ratiometric measurement. Both the ALPHAScreen and the TR-FRET assays were miniaturized to 8-μl volumes. Of the photomultiplier tube-based readers, the ALPHAScreen reader (ALPHAQuest) presented the advantage of faster reading times through simultaneous reading with four photomultiplier tubes.

fibrolamellar carcinoma drug repurposing pediatric rare tumors patient derived xenografts drug screening fusion gene Abbreviations: ATR -Ataxia telangiectasia and Rad3-related protein AURKA -Aurora kinase A AURKB -Aurora kinase B Bcl-xL -B-cell lymphoma-extra large encoded by the BCL2-like 1 gene Bcl2 -B-cell lymphoma 2 ITS -Insulin, (human) Transferrin, Selenium BID -BH3 Interacting Domain Death Agonist BIM -Bcl-2-like protein 11 CA12 -Carbonic anhydrase 12 CDc7 -Cell division cycle 7-related protein kinase CDK -Cyclin depedent protein kinase Cyp19A1 -Also know as aromatase or estrogen synthase DAB -3,3'-Diaminobenzidine DMSO -Dimethyl sulfoxide DNA-PK -DNA protein kinase EGFR -Epidermal growth factor receptor eIF4F -Eukaryotic initiation factor 4F ErbB2 -erythroblastic oncogene B, also known as Her-2 protooncogene Neu and as epidermal growth factor receptor-2 FLC -fibrolamellar hepatocellular carcinoma H&E -hematoxylin and eosin HSA -Highest Single Agent HCC -hepatocellular carcinoma HDAC -Histone deacetylase HSP70 -Heat Shock Protein 70

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Sensing and response to environmental cues, such as pH and chloride (Cl−), is critical in enabling Mycobacterium tuberculosis (Mtb) colonization of its host. Utilizing a fluorescent reporter Mtb strain in a chemical screen, we have identified compounds that dysregulate Mtb response to high Cl− levels, with a subset of the hits also inhibiting Mtb growth in host macrophages. Structure–activity relationship studies on the hit compound “C6,” or 2-(4-((2-(ethylthio)pyrimidin-5-yl)methyl)piperazin-1-yl)benzo[d]oxazole, demonstrated a correlation between compound perturbation of Mtb Cl− response and inhibition of bacterial growth in macrophages. C6 accumulated in both bacterial and host cells, and inhibited Mtb growth in cholesterol media, but not in rich media. Subsequent examination of the Cl− response of Mtb revealed an intriguing link with bacterial growth in cholesterol, with increased transcription of several Cl−-responsive genes in the simultaneous presence of cholesterol and high external Cl− concentration, versus transcript levels observed during exposure to high external Cl− concentration alone. Strikingly, oral administration of C6 was able to inhibit Mtb growth in vivo in a C3HeB/FeJ murine infection model. Our work illustrates how Mtb response to environmental cues can intersect with its metabolism and be exploited in antitubercular drug discovery.

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