| First Author | Fornari F | Year | 2014 |
| Journal | Mol Cancer Res | Volume | 12 |
| Issue | 2 | Pages | 203-16 |
| PubMed ID | 24324033 | Mgi Jnum | J:207906 |
| Mgi Id | MGI:5559926 | Doi | 10.1158/1541-7786.MCR-13-0312-T |
| Citation | Fornari F, et al. (2014) p53/mdm2 feedback loop sustains miR-221 expression and dictates the response to anticancer treatments in hepatocellular carcinoma. Mol Cancer Res 12(2):203-16 |
| abstractText | UNLABELLED: The overexpression of microRNA-221 (miR-221) is reported in several human cancers including hepatocellular carcinoma, and its targeting by tailored treatments has been proposed. The evidence supporting the role of miR-221 in cancer is growing and has been mainly focused on the discovery of miR-221 targets as well as on its possible therapeutic exploitations. However, the mechanism sustaining miR-221 aberrant expression remains to be elucidated. In this study, MDM2 (E3 ubiquitin-protein ligase homolog), a known p53 (TP53) modulator, is identified as a direct target of miR-221, and a feed-forward loop is described that sustains miR-221 aberrant expression. Interestingly, miR-221 can activate the p53/mdm2 axis by inhibiting MDM2 and, in turn, p53 activation contributes to miR-221 enhanced expression. Moreover, by modulating the p53 axis, miR-221 impacts cell-cycle progression and apoptotic response to doxorubicin in hepatocellular carcinoma-derived cell lines. Finally, CpG island methylation status was assessed as a causative event associated with miR-221 upregulation in hepatocellular carcinoma cells and primary tumor specimens. In hepatocellular carcinoma-derived cell lines, pharmacologically induced DNA hypomethylation potentiated a significant increase in miR-221 expression. These data were confirmed in clinical specimens of hepatocellular carcinoma in which elevated miR-221 expression was associated with the simultaneous presence of wild-type p53 and DNA hypomethylation. IMPLICATIONS: These findings reveal a novel miR-221-sustained regulatory loop that determines a p53-context-specific response to doxorubicin treatment in hepatocellular carcinoma. |
