title: Regulation of HIF-1alpha and VEGF by miR-20b tunes tumor cells to adapt to the alteration of oxygen concentration.
abstract: The regulation of HIF-1alpha is considered to be realized by pVHL-mediated ubiquitin-26S proteasome pathway at a post-transcriptional level. The discovery of a class of small noncoding RNAs, called microRNAs, implies alternative mechanism of regulation of HIF-1alpha. Here, we show that miR-20b plays an important role in fine-tuning the adaptation of tumor cells to oxygen concentration. The inhibition of miR-20b increased the protein levels of HIF-1alpha and VEGF in normoxic tumor cells; the increase of miR-20b in hypoxic tumor cells, nevertheless, decreased the protein levels of HIF-1alpha and VEGF. By using luciferase reporter vector system, we confirmed that miR-20b directly targeted the 3'UTR of Hif1a and Vegfa. On the other hand, the forced overexpression of HIF-1alpha in normoxic tumor cells downregulated miR-20b expression. However, HIF-1alpha knockdown in hypoxic tumor cells caused the increase of miR-20b. The differential expression of miR-20b has important biological significance in tumor cells, either enhancing the growth or favoring the survival of tumor cells upon the oxygen supply. Thus, we identify a novel molecular regulation mechanism through which miR-20b regulates HIF-1alpha and VEGF and is regulated by HIF-1alpha so to keep tumor cells adapting to different oxygen concentrations.
authors.affiliation: Department of Biochemistry & Molecular Biology, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, The People's Republic of China.
authors.forename: Zhang
authors.initials: Z
authors.lastname: Lei
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.forename: Zhuoshun
authors.initials: Z
authors.lastname: Yang
authors.forename: Haoshu
authors.initials: H
authors.lastname: Fang
authors.forename: Gui-Mei
authors.initials: GM
authors.lastname: Zhang
authors.forename: Zuo-Hua
authors.initials: ZH
authors.lastname: Feng
authors.forename: Bo
authors.initials: B
authors.lastname: Huang
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic; D005822:Genetic Vectors; D006801:Humans; D000860:Hypoxia; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D035683:MicroRNAs / Q000378:metabolism*; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology*; D010100:Oxygen / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; C534451:MIRN20a microRNA, human; D035683:MicroRNAs; D042461:Vascular Endothelial Growth Factor A; D010100:Oxygen