Optimization of a high-throughput fluorescence polarization assay for STAT5B DNA binding domain-targeting inhibitors

Protein-templated ligand discovery via the selection of DNA-encoded dynamic libraries

DNA-encoded chemical libraries (DELs) have become a powerful technology platform in drug discovery. Dual-pharmacophore DELs display two sets of small molecules at the termini of DNA duplexes, thereby enabling the identification of synergistic binders against biological targets, and have been successfully applied in fragment-based ligand discovery and affinity maturation of known ligands. However, dual-pharmacophore DELs identify separate binders that require subsequent linking to obtain the full ligands, which is often challenging. Here we report a protein-templated DEL selection approach that can identify full ligand/inhibitor structures from DNA-encoded dynamic libraries (DEDLs) without the need for subsequent fragment linking. Our approach is based on dynamic DNA hybridization and target-templated in situ ligand synthesis, and it incorporates and encodes the linker structures in the library, along with the building blocks, to be sampled by the target protein. To demonstrate the performance of this method, 4.35-million- and 3.00-million-member DEDLs with different library architectures were prepared, and hit selection was achieved against four therapeutically relevant target proteins.

An enzyme linked aptamer photoelectrochemical biosensor for Tau-381 protein using AuNPs/MoSe2 as sensing material

Alzheimer's disease is a worldwide health problem and it has attracted extensive attention. Tau protein is an important biomarker in the pathogenesis of Alzheimer's disease. Herein, we devise a in situ enzyme catalysis generating electron donor photoelectrochemical (PEC) biosensor for Tau-381 protein. Tau-381 protein aptamer is immobilized onto the surface of AuNPs/MoSe₂ nanosheets modified electrode. In the presence of Tau-381 protein, an aptamer-protein duplex is formed. Meanwhile, the Tau-381 antibody and the protein G/AP (protein G labeled with alkaline phosphatase) are captured with the affinity interaction between Tau-381 protein and Tau-381 antibody, Tau-381 antibody and protein G/AP. The electron donor, ascorbic acid, is in situ produced by the catalyzing of ascorbic acid 2-phosphate in the PEC detection solution. As a result, low blank noise and strong photocurrent response are engendered. The photocurrent response is related to the concentration of Tau-381 protein. The detection range of Tau-381 protein is from 0.5 fM to 1.0 nM with detection limit of 0.3 fM. This in situ generating electron donor PEC biosensor can detect various targets by simply alternating antibody, antigen, or aptamer commercially. Thus, this work represents a simple and general sensing protocol.

Optimizations of a novel fluorescence polarization-based high-throughput screening assay for β-catenin/LEF1 interaction inhibitors

Aberrant activation of the Wnt/β-catenin signaling pathway is prominent in the development and metastasis of non-small cell lung cancer (NSCLC). Highly effective inhibition of this pathway highlights a therapeutic avenue against NSCLC. Moreover, β-catenin/LEF1 interaction regulates β-catenin nuclear transport as well as the transcriptions of the key oncogenes in Wnt/β-catenin signaling pathway. Therefore, interruption of this interaction would be a promising therapeutic strategy for NSCLC metastasis. To date, no economical and rapid high-throughput screening (HTS) assay has been reported for the discovery of β-catenin/LEF1 interaction inhibitors. In this study, we developed a novel fluorescence polarization (FP)-based HTS assay to identify β-catenin/LEF1 interaction inhibitors. The FITC-LEF1 sequence, incubation time, temperature, and DMSO resistance were optimized, and then a high Z' factor of 0.77 was achieved. A pilot screening of a natural product library via this established FP screening assay identified sanguinarine analogues as potential β-catenin/LEF1 interaction inhibitors. GST pull-down and surface plasmon resonance (SPR) assay demonstrated that β-catenin/LEF1 interaction is a potential anticancer target of sanguinarine in vitro. This newly developed FP screening assay will be vital for the rapid discovery of novel Wnt inhibitors targeting β-catenin/LEF1 interaction.

STAT3 transcription factor as target for anti-cancer therapy

STATs constitute a large family of transcription activators and transducers of signals that have an important role in many cell functions as regulation of proliferation and differentiation of the cell also regulation of apoptosis and angiogenesis. STAT3 as a member of that family, recently was discovered to have a vital role in progression of different types of cancers. The activation of STAT3 was observed to regulate multiple gene functions during cancer-like cell proliferation, differentiation, apoptosis, metastasis, inflammation, immunity, cell survival, and angiogenesis. The inhibition of STAT3 activation has been an important target for cancer therapy. Inhibitors of STAT3 have been used for a long time for treatment of many types of cancers like leukemia, melanoma, colon, and renal cancer. In this review article, we summarize and discuss different drugs inhibiting the action of STAT3 and used in treatment of different types of cancer.