Discovery of a Potent GLUT Inhibitor from a Library of Rapafucins by Using 3D Microarrays

Glucose transporters play an essential role in cancer cell proliferation and survival and have been pursued as promising cancer drug targets. Using microarrays of a library of new macrocycles known as rapafucins, which were inspired by the natural product rapamycin, we screened for new inhibitors of GLUT1. We identified multiple hits from the rapafucin 3D microarray and confirmed one hit as a bona fide GLUT1 ligand, which we named rapaglutin A (RgA). We demonstrate that RgA is a potent inhibitor of GLUT1 as well as GLUT3 and GLUT4, with an IC₅₀ value of low nanomolar for GLUT1. RgA was found to inhibit glucose uptake, leading to a decrease in cellular ATP synthesis, activation of AMP‐dependent kinase, inhibition of mTOR signaling, and induction of cell‐cycle arrest and apoptosis in cancer cells. Moreover, RgA was capable of inhibiting tumor xenografts in vivo without obvious side effects. RgA could thus be a new chemical tool to study GLUT function and a promising lead for developing anticancer drugs.     

Furo[3,2‐b]pyridine: A Privileged Scaffold for Highly Selective Kinase Inhibitors and Effective Modulators of the Hedgehog Pathway

Reported is the identification of the furo[3,2‐b]pyridine core as a novel scaffold for potent and highly selective inhibitors of cdc‐like kinases (CLKs) and efficient modulators of the Hedgehog signaling pathway. Initially, a diverse target compound set was prepared by synthetic sequences based on chemoselective metal‐mediated couplings, including assembly of the furo[3,2‐b]pyridine scaffold by copper‐mediated oxidative cyclization. Optimization of the subseries containing 3,5‐disubstituted furo[3,2‐b]pyridines afforded potent, cell‐active, and highly selective inhibitors of CLKs. Profiling of the kinase‐inactive subset of 3,5,7‐trisubstituted furo[3,2‐b]pyridines revealed sub‐micromolar modulators of the Hedgehog pathway.