2022-09-282022-09-282021https://repository.tcu.edu/handle/116099117/55825Itraconazole, an FDA-approved antifungal, has antitumor activity against a variety of cancers. We sought to determine the effects of itraconazole on esophageal cancer and elucidate its mechanism of action. Itraconazole inhibited cell proliferation and induced G1-phase cell-cycle arrest in esophageal squamous cell carcinoma and adenocarcinoma cell lines. Using an unbiased kinase array, we found that itraconazole downregulated protein kinase AKT phosphorylation in OE33 esophageal adenocarcinoma cells. Itraconazole also decreased phosphorylation of downstream ribosomal protein S6, transcriptional expression of the upstream receptor tyrosine kinase HER2, and phosphorylation of upstream PI3K in esophageal cancer cells. Lapatinib, a tyrosine kinase inhibitor that targets HER2, and siRNA-mediated knockdown of HER2 similarly suppressed cancer cell growth in vitro. Itraconazole significantly inhibited growth of OE33-derived flank xenografts in mice with detectable levels of itraconazole and its primary metabolite, hydroxyitraconazole, in esophagi and tumors. HER2 total protein and phosphorylation of AKT and S6 proteins were decreased in xenografts from itraconazole-treated mice compared to xenografts from placebo-treated mice. In an early phase I clinical trial (NCT02749513) in patients with esophageal cancer, itraconazole decreased HER2 total protein expression and phosphorylation of AKT and S6 proteins in tumors. These data demonstrate that itraconazole has potent antitumor properties in esophageal cancer, partially through blockade of HER2/AKT signaling. ©2021 The Authors; Published by the American Association for Cancer Research2021 The Authorshttps://creativecommons.org/licenses/by-nc-nd/4.0/epidermal growth factor receptor 2hydroxyitraconazoleitraconazolelapatinibphosphatidylinositol 3 kinaseplaceboprotein kinase Bprotein S6small interfering RNAtyrosine kinase receptorAKT1 protein, humancytochrome P450 3A inhibitorepidermal growth factor receptor 2ERBB2 protein, humanitraconazoleprotein kinase BadultagedAkt signalinganimal experimentanimal modelantineoplastic activityArticlecancer growthcancer inhibitioncancer modelcancer patientcell cycle arrestcell cycle G1 phasecell cycle M phasecell cycle S phasecell proliferationclinical articlecomparative studycontrolled studydown regulationelectrosprayesophageal adenocarcinomaesophageal squamous cell carcinomaesophagogastroduodenoscopyFLO-1 cell lineG1 phase cell cycle checkpointgene expressiongenetic transcriptionhumanhuman cellin vitro studyKYSE-510 cell lineKYSE-70 cell lineliquid chromatography-mass spectrometrymalemousenonhumanOE33 cell linepolyacrylamide gel electrophoresisprotein expressionprotein phosphorylationreal time polymerase chain reactionsignal transductiontumor volumetumor xenograftultra performance liquid chromatographyunspecified side effectanimalapoptosisBagg albino mousecell cyclecell motionclinical trialdrug effectdrug screeningesophageal squamous cell carcinomaesophagus tumorfemalegene expression regulationmaximum tolerated dosemetabolismnude mousepathologyphase 1 clinical trialprognosistissue distributiontumor cell cultureAnimalsApoptosisCell CycleCell MovementCell ProliferationCytochrome P-450 CYP3A InhibitorsEsophageal NeoplasmsEsophageal Squamous Cell CarcinomaFemaleGene Expression Regulation, NeoplasticHumansItraconazoleMaximum Tolerated DoseMiceMice, Inbred BALB CMice, NudePrognosisProto-Oncogene Proteins c-aktReceptor, ErbB-2Tissue DistributionTumor Cells, CulturedXenograft Model Antitumor AssaysArticleCC BY-NC-ND 4.0https://doi.org/10.1158/1535-7163.MCT-20-0638