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- Title
Upregulation of miR-27a contributes to the malignant transformation of human bronchial epithelial cells induced by SV40 small T antigen.
- Authors
Wang, Q; Li, D-C; Li, Z-F; Liu, C-X; Xiao, Y-M; Zhang, B; Li, X-D; Zhao, J; Chen, L-P; Xing, X-M; Tang, S-F; Lin, Y-C; Lai, Y-D; Yang, P; Zeng, J-L; Xiao, Q; Zeng, X-W; Lin, Z-N; Zhuang, Z-X; Zhuang, S-M
- Abstract
The introduction of the Simian virus 40 (SV40) early region, the telomerase catalytic subunit (hTERT) and an oncogenic allele of H-Ras directly transforms primary human cells. SV40 small T antigen (ST), which forms a complex with protein phosphatase 2A (PP2A) and inhibits PP2A activity, is believed to have a critical role in the malignant transformation of human cells. Recent evidence has shown that aberrant microRNA (miRNA) expression patterns are correlated with cancer development. Here, we identified miR-27a as a differentially expressed miRNA in SV40 ST-expressing cells. miR-27a is upregulated in SV40 ST-transformed human bronchial epithelial cells (HBERST). Suppression of miR-27a expression in HBERST cells or lung cancer cell lines (NCI-H226 and SK-MES-1) that exhibited high levels of miR-27a expression lead to cell growth arrested in the G0-G1 phase. In addition, suppression of miR-27a in HBERST cells attenuated the capacity of such cells to grow in an anchorage-independent manner. We also found that suppression of the PP2A B56γ expression resulted in upregulation of miR-27a similar to that achieved by the introduction of ST, indicating that dysregulation of miR-27a expression in ST-expressing cells was mediated by the ST-PP2A interaction. Moreover, we discovered that Fbxw7 gene encoding F-box/WD repeat-containing protein 7 was a potential miR-27a target validated by dual-luciferase reporter system analysis. The inverse correlation between miR-27a expression levels and Fbxw7 protein expression was further confirmed in both cell models and human tumor samples. Fbxw7 regulates cell-cycle progression through the ubiquitin-dependent proteolysis of a set of substrates, including c-Myc, c-Jun, cyclin E1 and Notch 1. Thus, promotion of cell growth arising from the suppression of Fbxw7 by miR-27a overexpression might be responsible for the viral oncoprotein ST-induced malignant transformation. These observations demonstrate that miR-27a functions as an oncogene in human tumorigenesis.
- Subjects
SV40 (Virus); EPITHELIAL cells; GENETIC regulation; GENETIC transformation; TELOMERASE; GENE frequency; PHOSPHOPROTEIN phosphatases; NON-coding RNA
- Publication
Oncogene, 2011, Vol 30, Issue 36, p3875
- ISSN
0950-9232
- Publication type
Article
- DOI
10.1038/onc.2011.103