title: Genetic alterations in microRNAs in medulloblastomas.
abstract: MicroRNAs (miRNAs) regulate a variety of cellular processes via the regulation of multiple target genes. We screened 48 medulloblastomas for mutation, deletion and amplification of nine miRNA genes that were selected on the basis of the presence of potential target sequences within the 3'-untranslated region of the MYCC mRNA. Differential PCR revealed deletions in miR-186 (15%), miR-135a-1 (33%), miR-548d-1 (42%), miR-548d-2 (21%) and miR-512-2 (33%) genes, whereas deletion or amplification was detected in miR-135b (23%) and miR-135a-2 (15%). In miR-33b, deletion, amplification or a mutation at the precursor miRNA were detected in 10% of medulloblastomas. Overall, 35/48 (73%) medulloblastomas had at least one alteration. Real-time RT-PCR revealed MYCC overexpression in 11 of 37 (30%) medulloblastomas, and there was a correlation between MYCC overexpression and miR-512-2 gene deletion (P = 0.0084). Antisense-based knockdown of miR-512-5p (mature sequence of miR-512-2) resulted in significant upregulation of MYCC expression in HeLa and A549 cells, while forced overexpression of miR-512-2 in medulloblastoma/PNET cell lines DAOY, UW-228-2, PFSK resulted in the downregulation of MYCC protein. Furthermore, the results of luciferase reporter assays suggested that miR-512-2 targets the MYCC gene. These results suggest that alterations in the miRNA genes may be an alternative mechanism leading to MYCC overexpression in medulloblastomas.
authors.affiliation: International Agency for Research on Cancer (IARC), Lyon, France Neuro-Oncology Program, University Children's Hospital of Zurich, Switzerland.
authors.forename: Sheng-Qing
authors.initials: SQ
authors.lastname: Lv
authors.forename: Young-Ho
authors.initials: YH
authors.lastname: Kim
authors.forename: Fiaschetti
authors.initials: F
authors.lastname: Giulio
authors.forename: Tarek
authors.initials: T
authors.lastname: Shalaby
authors.forename: Sumihito
authors.initials: S
authors.lastname: Nobusawa
authors.forename: Hui
authors.initials: H
authors.lastname: Yang
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhou
authors.forename: Michael
authors.initials: M
authors.lastname: Grotzer
authors.forename: Hiroko
authors.initials: H
authors.lastname: Ohgaki
mesh_terms: D000293:Adolescent; D000328:Adult; D002528:Cerebellar Neoplasms / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005784:Gene Amplification / Q000235:genetics; D017353:Gene Deletion; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005820:Genetic Testing; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D007223:Infant; D008175:Lung Neoplasms; D008297:Male; D008527:Medulloblastoma / Q000235:genetics*; D035683:MicroRNAs / Q000235:genetics*; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics; D055815:Young Adult
chemical_list: C489427:MYC protein, human; D035683:MicroRNAs; D016271:Proto-Oncogene Proteins c-myc