title: miR-125b controls apoptosis and temozolomide resistance by targeting TNFAIP3 and NKIRAS2 in glioblastomas.
abstract: Diffusely infiltrating gliomas are among the most prognostically discouraging neoplasia in human. Temozolomide (TMZ) in combination with radiotherapy is currently used for the treatment of glioblastoma (GBM) patients, but less than half of the patients respond to therapy and chemoresistance develops rapidly. Epigenetic silencing of the O(6)-methylguanine-DNA methyltransferase (MGMT) has been associated with longer survival in GBM patients treated with TMZ, but nuclear factor κB (NF-κB)-mediated survival signaling and TP53 mutations contribute significantly to TMZ resistance. Enhanced NF-κB is in part owing to downregulation of negative regulators of NF-κB activity, including Tumor necrosis factor alpha-induced protein 3 (TNFAIP3) and NF-κB inhibitor interacting RAS-like 2 (NKIRAS2). Here we provide a novel mechanism independent of TP53 and MGMT by which oncogenic miR-125b confers TMZ resistance by targeting TNFAIP3 and NKIRAS2. GBM cells overexpressing miR-125b showed increased NF-κB activity and upregulation of anti-apoptotic and cell cycle genes. This was significantly associated with resistance of GBM cells to TNFα- and TNF-related inducing ligand-induced apoptosis as well as resistance to TMZ. Conversely, overexpression of anti-miR-125b resulted in cell cycle arrest, increased apoptosis and increased sensitivity to TMZ, indicating that endogenous miR-125b is sufficient to control these processes. GBM cells overexpressing TNFAIP3 and NKIRAS2 were refractory to miR-125b-induced apoptosis resistance as well as TMZ resistance, indicating that both genes are relevant targets of miR-125b. In GBM tissues, high miR-125b expression was significantly correlated with nuclear NF-κB confirming that miR-125b is implicated in NF-κB signaling. Most remarkably, miR-125b overexpression was clearly associated with shorter overall survival of patients treated with TMZ, suggesting that this microRNA is an important predictor of response to therapy.
authors.affiliation: Institut für Pathologie, University of Bern, Bern, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Haemmig
authors.affiliation: Institut für Pathologie, University of Bern, Bern, Switzerland.
authors.forename: U
authors.initials: U
authors.lastname: Baumgartner
authors.affiliation: Institut für Pathologie, University of Bern, Bern, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Glück
authors.affiliation: Institut für Pathologie, University of Bern, Bern, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Zbinden
authors.affiliation: Institut für Pathologie, University of Bern, Bern, Switzerland.
authors.forename: M P
authors.initials: MP
authors.lastname: Tschan
authors.affiliation: Institut für Pathologie, University of Bern, Bern, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Kappeler
authors.affiliation: Klinik und Poliklinik, University Hospital Basel, Basel, Switzerland.
authors.forename: L
authors.initials: L
authors.lastname: Mariani
authors.affiliation: Institut für Pathologie, University of Bern, Bern, Switzerland.
authors.forename: I
authors.initials: I
authors.lastname: Vajtai
authors.affiliation: Institut für Pathologie, University of Bern, Bern, Switzerland.
authors.forename: E
authors.initials: E
authors.lastname: Vassella
mesh_terms: D017209:Apoptosis; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D005909:Glioblastoma / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D012334:RNA, Neoplasm / Q000494:pharmacology*; D000077204:Temozolomide; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C531888:MIRN125 microRNA, human; D035683:MicroRNAs; D009687:Nuclear Proteins; D012334:RNA, Neoplasm; D003606:Dacarbazine; C076529:TNFAIP3 protein, human; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D018631:ras Proteins; D000077204:Temozolomide