levoleucovorin and fludarabine-phosphate

Inositol-requiring enzyme 1 (IRE1) is a bifunctional serine/threonine kinase and endoribonuclease that is a major mediator of the unfolded protein response (UPR) during endoplasmic reticulum (ER) stress. Tumour cells experience ER stress due to adverse environmental cues such as hypoxia or nutrient shortage and high metabolic/protein-folding demand. To cope with those stresses, cancer cells utilise IRE1 signalling as an adaptive mechanism. Here, we report the discovery of the FDA-approved compounds methotrexate, cefoperazone, folinic acid and fludarabine phosphate as IRE1 inhibitors. These were identified through a structural exploration of the IRE1 kinase domain using IRE1 peptide fragment docking and further optimisation and pharmacophore development. The inhibitors were verified to have an impact on IRE1 activity in vitro and were tested for their ability to sensitise human cell models of glioblastoma multiforme (GBM) to chemotherapy. We show that all molecules identified sensitise glioblastoma cells to the standard-of-care chemotherapy temozolomide (TMZ).

Topics: Cefoperazone; Cell Line, Tumor; Drug Approval; Endoplasmic Reticulum Stress; Endoribonucleases; Enzyme Inhibitors; Humans; Leucovorin; Methotrexate; Molecular Structure; Peptidomimetics; Protein Binding; Protein Domains; Protein Serine-Threonine Kinases; Signal Transduction; Unfolded Protein Response; United States; United States Food and Drug Administration; Vidarabine Phosphate