KG-548 is an ARNT/TACC3 disruptor and HIF-1α inhibitor. It competitively binds the ARNT PAS-B domain with TACC3, directly interfering with the formation of the ARNT/TACC3 complex. ARNT, also known as HIF-β, stands for aryl hydrocarbon receptor nuclear translocator [1][2].

Hypoxia-inducible factor (HIF) consists of a heterodimer formed by two basic Helix Loop Helix-Per-ARNT-Sim (bHLH-PAS) subunits, including one of the HIF-α paralogs (HIF-1α, -2α, -3α) and the aryl hydrocarbon receptor nuclear translocator (ARNT, also known as HIF-β). KG-548 demonstrates a significant reduction in the formation of the ARNT/CCC complex across coactivators, and disrupts the interactions between ARNT2 PAS-B and TACC3. A dose-dependent disruption by KG-548 of the ARNT PAS-B/TACC3 complex at concentrations of 0 to 2 mM, over 16 hours overnight, was observed, effectively dissociating a 320 μM complex in vitro and in cell lysates, with an IC50 value of 25 μM. Moreover, KG-548 markedly reduces lactate production in glycolysis in FaDu hypopharyngeal carcinoma cells. Western Blot Analysis in HEK293T cell lysates, using concentrations ranging from 0, 5, 50, 100, 250, 500 μM to 1 mM and 2 mM over 16 hours, showed a dose-dependent weakening of the ARNT/TACC3 interaction beginning at 5 μM, and resulted in a significant decrease in protein intensity of ARNT associated with immunoprecipitated TACC3 protein by 82% (500 μM), 59% (1 mM), and 43% (2 mM), respectively.