title: Ursolic acid inhibits proliferation and induces apoptosis in human glioblastoma cell lines U251 by suppressing TGF-β1/miR-21/PDCD4 pathway.
abstract: New chemotherapeutic strategy should be investigated to enhance clinical management in human gliomas. Recently, ursolic acid (UA), as a naturally occurring pentacyclic triterpene, has exhibited a potent anticancer activity in various tumour cells but remains uncertain in human glioma cells. Here, we examined whether UA could suppress the proliferation of human glioma cell line U251, and if so, its possible molecular targets. Cell survival, apoptosis and molecular targets were identified by multiple detecting techniques, including trypan blue dye exclusion assay, electron microscopy, AO/EB staining, Real-time PCR and immunoblotting in U251 cells. The results showed that 5-20 μM of UA suppressed proliferation and induced apoptosis of U251 cells in dose- and time-dependent manners. UA increased the activation of caspase-3 and markedly suppressed levels of microRNA-21 (miR-21) in a time-dependent manner. The expression of programmed cell death 4 (PDCD4), which is a miR-21 targeting apoptotic gene, has also been enhanced by UA. And over-expression of miR-21 in U251 cells abolished the enhancement of PDCD4 protein by UA. More importantly, TGF-β1/smads signalling, as critical upstream regulators of miR-21, has also been suppressed by UA. These findings suggest that UA inhibits cell growth via causing apoptosis in U251 cells by a UA-triggered TGF-β1/miR-21/PDCD4 pathway. This study provides an evidence for testing UA efficacy in vivo and warranting future investigations examining the clinical potential of UA in human gliomas.
authors.affiliation: Department of Neurosurgery, The Second Affiliated Hospital of Harbin Medical University, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Yongli
authors.initials: Y
authors.lastname: Li
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Wang
authors.forename: Chuanlu
authors.initials: C
authors.lastname: Jiang
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D005909:Glioblastoma / Q000188:drug therapy / Q000473:pathology*; D006801:Humans; D035683:MicroRNAs / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction; D053773:Transforming Growth Factor beta1 / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D014315:Triterpenes / Q000494:pharmacology*; D000097245:Ursolic Acid
chemical_list: D051017:Apoptosis Regulatory Proteins; D053148:Caspase 3; D035683:MicroRNAs; D016601:RNA-Binding Proteins; D053773:Transforming Growth Factor beta1; D014315:Triterpenes; D000097245:Ursolic Acid; C524940:MIRN21 microRNA, human; C114487:PDCD4 protein, human; C505407:CASP3 protein, human