title: Overexpression of IRF9 confers resistance to antimicrotubule agents in breast cancer cells.
abstract: IRF9/p48/ISGF3gamma (IRF9) is an IFN regulatory factor that mediates signaling by type I IFNs (IFNalpha and IFNbeta). After single-step selection of breast adenocarcinoma cells in paclitaxel, differential display and single gene analysis demonstrated that transcriptional activation of IRF9 and other IFN-responsive genes, independent of IFN, corresponded with resistance to antimicrotubule agents. Transient overexpression of IRF9 reproduced the drug-resistance phenotype and induced expression of IFN-responsive genes. However, drug resistance was not induced by overexpression of Stat1 or Stat2, or treatment with IFNalpha per se. Using a donor-matched array of cDNA prepared from human tumor and normal tissue from a variety of organs, we observed overexpression of IRF9 in approximately one-half of breast and uterine tumors, which indicated that IRF9 may be important in signaling in these tumor types. These data identify a novel IFN-independent role for IRF9 in the development of resistance to antimicrotubule agents in breast tumor cells and may link downstream mediators of IFN signaling to drug resistance in human cancers.
authors.affiliation: Department of Radiology, Washington University Medical School, St. Louis, Missouri 63110, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Luker
authors.forename: C M
authors.initials: CM
authors.lastname: Pica
authors.forename: R D
authors.initials: RD
authors.lastname: Schreiber
authors.forename: D
authors.initials: D
authors.lastname: Piwnica-Worms
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D004317:Doxorubicin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000502:physiology; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007370:Interferon Type I / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D008870:Microtubules / Q000187:drug effects; D017239:Paclitaxel / Q000494:pharmacology*; D015398:Signal Transduction / Q000502:physiology; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D014162:Transfection; D014407:Tumor Cells, Cultured; D014594:Uterine Neoplasms / Q000235:genetics / Q000378:metabolism; D014747:Vinblastine / Q000494:pharmacology
chemical_list: D000903:Antibiotics, Antineoplastic; D000972:Antineoplastic Agents, Phytogenic; D004268:DNA-Binding Proteins; C494227:IRF9 protein, human; D007370:Interferon Type I; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D014157:Transcription Factors; D014747:Vinblastine; D004317:Doxorubicin; D017239:Paclitaxel