MicroRNA-221 targets Bmf in hepatocellular carcinoma and correlates with tumor multifocality.
Deregulated cell proliferation and apoptosis play a major role in hepatocellular carcinoma (HCC). MicroRNAs participate in the modulation of key molecules linked to hepatocarcinogenesis.


OBJECTIVE
This study aims to investigate the role of miR-221 in the modulation of Bmf, a proapoptotic BH3-only protein, and to characterize miR-221 contribution to hepatocarcinogenesis through modulation of apoptosis.


METHODS
Transfection of miR-221 and anti-miR-221 in HCC-derived cell lines and luciferase reporter assay were used to assess Bmf as a target of miR-221. Modulation of miR-221 and Bmf expression contributed to characterize their role in anoikis. Primary HCC tissues were analyzed to assess the clinical relevance of in vitro findings.


RESULTS
Enforced miR-221 expression caused Bmf down-regulation, whereas anti-miR-221 induced its up-regulation. A luciferase reporter assay confirmed Bmf as a target of miR-221. Following matrix detachment, miR-221 silencing led to increased apoptotic cell death. The analysis of HCC tissues revealed an inverse correlation between miR-221 and Bmf expression and a direct correlation between Bmf and activated caspase-3, as a marker of apoptosis. High miR-221 levels were associated with tumor multifocality and reduced time to recurrence after surgery.


CONCLUSIONS
Our results indicate that miR-221, by targeting Bmf, inhibits apoptosis. Moreover, in HCC, miR-221 overexpression is associated with a more aggressive phenotype. These findings, together with the previously reported modulation of CDKN1B/p27 and CDKN1C/p57, show that miR-221 simultaneously affects multiple pro-oncogenic pathways and suggest miR-221 as a potential target for nonconventional treatment against HCC.
Gramantieri
Laura
L
Dipartimento di Medicina Interna e Gastroenterologia e Centro di Ricerca Biomedica Applicata, Università di Bologna, Bologna, Italy. laura.gramantieri@aosp.bo.it
Fornari
Francesca
F
Ferracin
Manuela
M
Veronese
Angelo
A
Sabbioni
Silvia
S
Calin
George Adrian
GA
Grazi
Gian Luca
GL
Croce
Carlo Maria
CM
Bolondi
Luigi
L
Negrini
Massimo
M
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics*; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D018390:Gene Targeting; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D008297:Male; D035683:MicroRNAs / Q000037:antagonists & inhibitors / Q000502:physiology*; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D009378:Neoplasms, Multiple Primary / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D034741:RNA, Small Interfering / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D048868:Adaptor Proteins, Signal Transducing; D035683:MicroRNAs; D034741:RNA, Small Interfering; C486655:BMF protein, human; C525709:MIR221, human