title: Targeting of the Bmi-1 oncogene/stem cell renewal factor by microRNA-128 inhibits glioma proliferation and self-renewal.
abstract: MicroRNAs (miR) show characteristic expression signatures in various cancers and can profoundly affect cancer cell behavior. We carried out miR expression profiling of human glioblastoma specimens versus adjacent brain devoid of tumor. This revealed several significant alterations, including a pronounced reduction of miR-128 in tumor samples. miR-128 expression significantly reduced glioma cell proliferation in vitro and glioma xenograft growth in vivo. miR-128 caused a striking decrease in expression of the Bmi-1 oncogene, by direct regulation of the Bmi-1 mRNA 3'-untranslated region, through a single miR-128 binding site. In a panel of patient glioblastoma specimens, Bmi-1 expression was significantly up-regulated and miR-128 was down-regulated compared with normal brain. Bmi-1 functions in epigenetic silencing of certain genes through epigenetic chromatin modification. We found that miR-128 expression caused a decrease in histone methylation (H3K27me(3)) and Akt phosphorylation, and up-regulation of p21(CIP1) levels, consistent with Bmi-1 down-regulation. Bmi-1 has also been shown to promote stem cell self-renewal; therefore, we investigated the effects of miR-128 overexpression in human glioma neurosphere cultures, possessing features of glioma "stem-like" cells. This showed that miR-128 specifically blocked glioma self-renewal consistent with Bmi-1 down-regulation. This is the first example of specific regulation by a miR of a neural stem cell self-renewal factor, implicating miRs that may normally regulate brain development as important biological and therapeutic targets against the "stem cell-like" characteristics of glioma.
authors.affiliation: Dardinger Laboratory for Neuro-oncology and Neurosciences, Department of Neurological Surgery, The Ohio State University Medical Center and James Comprehensive Cancer Center, Columbus, Ohio 43210
authors.forename: Jakub
authors.initials: J
authors.lastname: Godlewski
authors.forename: Michal O
authors.initials: MO
authors.lastname: Nowicki
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Bronisz
authors.forename: Shanté
authors.initials: S
authors.lastname: Williams
authors.forename: Akihiro
authors.initials: A
authors.lastname: Otsuki
authors.forename: Gerard
authors.initials: G
authors.lastname: Nuovo
authors.forename: Abhik
authors.initials: A
authors.lastname: Raychaudhury
authors.forename: Herbert B
authors.initials: HB
authors.lastname: Newton
authors.forename: E Antonio
authors.initials: EA
authors.lastname: Chiocca
authors.forename: Sean
authors.initials: S
authors.lastname: Lawler
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D005910:Glioma / Q000473:pathology / Q000628:therapy*; D006801:Humans; D051379:Mice; D035683:MicroRNAs / Q000235:genetics*; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D063150:Polycomb Repressive Complex 1; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D012097:Repressor Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics
chemical_list: C069077:BMI1 protein, human; C489421:Bmi1 protein, mouse; D035683:MicroRNAs; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D063150:Polycomb Repressive Complex 1