Recent evidence shows that hypoxia-inducible factor 2 alpha (HIF-2α) may have critical roles in the growth and progression of neuroblastoma (NB) under non-hypoxic conditions. However, the underlying mechanisms and clinical potentials of normoxic HIF-2α expression in NB still remain largely unknown. In this study, HIF-2α immunostaining was identified in 26/42 NB tissues, which was correlated with clinicopathological features. In subtotal 20 NB cases, microRNA-145 (miR-145) was downregulated and inversely correlated with HIF-2α expression. Bioinformatics analysis revealed a putative miR-145 binding site in the 3′-untranslated region (3′-UTR) of HIF-2α messenger RNA (mRNA). Overexpression or knockdown of miR-145 responsively altered both the mRNA and protein levels of HIF-2α and its downstream genes, cyclin D1, matrix metalloproteinase 14 and vascular endothelial growth factor, in normoxically cultured NB cell lines SH-SY5Y and SK-N-SH. In a luciferase reporter system, miR-145 downregulated the luciferase activity of HIF-2α 3′-UTR, and these effects were abolished by a mutation in the putative miR-145-binding site. Overexpression of miR-145 suppressed the growth, invasion, metastasis and angiogenesis of SH-SY5Y and SK-N-SH cells in vitro and in vivo, while restoration of HIF-2α expression rescued the tumor cells from miR-145-mediated defects in these biological features. Furthermore, anti-miR-145 inhibitor rescued the HIF-2α knockdown-mediated repression on the growth, migration, invasion and angiogenesis of NB cells. These data indicate that miR-145 suppresses HIF-2α expression via the binding site in the 3′-UTR under normoxic conditions, thus inhibiting the aggressiveness and angiogenesis of NB.
|Number of pages||11|
|State||Published - Jan 16 2014|
Bibliographical noteFunding Information:
This work was supported by the National Natural Science Foundation of China (Nos. 30600278, 30772359, 81071997, 81072073, 81272779), Program for New Century Excellent Talents in University (NCET-06-0641), Scientific Research Foundation for the Returned Overseas Chinese Scholars (2008–889) and Fundamental Research Funds for the Central Universities (2012QN224).
- hypoxia-inducible factor 2 alpha
ASJC Scopus subject areas
- Molecular Biology
- Cancer Research