title: A genome-wide miRNA screen revealed miR-603 as a MGMT-regulating miRNA in glioblastomas.
abstract: MGMT expression is a critical determinant for therapeutic resistance to DNA alkylating agents. We previously demonstrated that MGMT expression is post-transcriptionally regulated by miR-181d and other miRNAs. Here, we performed a genome-wide screen to identify MGMT regulating miRNAs. Candidate miRNAs were further tested for inverse correlation with MGMT expression in clinical specimens. We identified 15 candidate miRNAs and characterized the top candidate, miR-603. Transfection of miR-603 suppressed MGMT mRNA/protein expression in vitro and in vivo; this effect was reversed by transfection with antimiR-603. miR-603 affinity-precipitated with MGMT mRNA and suppressed luciferase activity in an MGMT-3'UTR-luciferase assay, suggesting direct interaction between miR-603 and MGMT 3'UTR. miR-603 transfection enhanced the temozolomide (TMZ) sensitivity of MGMT-expressing glioblastoma cell lines. Importantly, miR-603 mediated MGMT suppression and TMZ resistance were reversed by expression of an MGMT cDNA. In a collection of 74 clinical glioblastoma specimens, both miR-603 and miR-181d levels inversely correlated with MGMT expression. Moreover, a combined index of the two miRNAs better reflected MGMT expression than each individually. These results suggest that MGMT is co-regulated by independent miRNAs. Characterization of these miRNAs should contribute toward strategies for enhancing the efficacy of DNA alkylating agents.
authors.affiliation: Dept. of Radiation Oncology, Dana-Farber Cancer Institute, Boston, MA; These authors contributed equally as first authors.
authors.forename: Deepa
authors.initials: D
authors.lastname: Kushwaha
authors.affiliation: Center for Theoretical and Applied Neuro-Oncology, Moores Cancer Center, Division of Neurosurgery, University of California San Diego, San Diego, CA. These authors contributed equally as first authors.
authors.forename: Valya
authors.initials: V
authors.lastname: Ramakrishnan
authors.affiliation: Dept. of Radiation Oncology, Dana-Farber Cancer Institute, Boston, MA.
authors.forename: Kimberly
authors.initials: K
authors.lastname: Ng
authors.affiliation: Center for Theoretical and Applied Neuro-Oncology, Moores Cancer Center, Division of Neurosurgery, University of California San Diego, San Diego, CA.
authors.forename: Tyler
authors.initials: T
authors.lastname: Steed
authors.affiliation: Center for Theoretical and Applied Neuro-Oncology, Moores Cancer Center, Division of Neurosurgery, University of California San Diego, San Diego, CA.
authors.forename: Thien
authors.initials: T
authors.lastname: Nguyen
authors.affiliation: Center for Theoretical and Applied Neuro-Oncology, Moores Cancer Center, Division of Neurosurgery, University of California San Diego, San Diego, CA.
authors.forename: Diahnn
authors.initials: D
authors.lastname: Futalan
authors.affiliation: Center for Theoretical and Applied Neuro-Oncology, Moores Cancer Center, Division of Neurosurgery, University of California San Diego, San Diego, CA.
authors.forename: Johnny C
authors.initials: JC
authors.lastname: Akers
authors.affiliation: Mayo Clinic, Department of Radiation Oncology, Rochester, MN.
authors.forename: Jann
authors.initials: J
authors.lastname: Sarkaria
authors.affiliation: Department of Neurosurgery, Tiantan Medical Center, Beijing, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Jiang
authors.affiliation: Dept. of Radiation Oncology, Dana-Farber Cancer Institute, Boston, MA.
authors.forename: Dipanjan
authors.initials: D
authors.lastname: Chowdhury
authors.affiliation: Center for Theoretical and Applied Neuro-Oncology, Moores Cancer Center, Division of Neurosurgery, University of California San Diego, San Diego, CA.
authors.forename: Bob S
authors.initials: BS
authors.lastname: Carter
authors.affiliation: Center for Theoretical and Applied Neuro-Oncology, Moores Cancer Center, Division of Neurosurgery, University of California San Diego, San Diego, CA.
authors.forename: Clark C
authors.initials: CC
authors.lastname: Chen
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics*; D001932:Brain Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism* / Q000401:mortality; D049109:Cell Proliferation; D015254:DNA Modification Methylases / Q000235:genetics* / Q000378:metabolism; D045643:DNA Repair Enzymes / Q000235:genetics* / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D005909:Glioblastoma / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism* / Q000401:mortality; D006801:Humans; D035683:MicroRNAs / Q000235:genetics; D011379:Prognosis; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; D035683:MicroRNAs; D025521:Tumor Suppressor Proteins; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D045643:DNA Repair Enzymes