Hepatitis C virus proteins modulate microRNA expression and chemosensitivity in malignant hepatocytes.
OBJECTIVE
Hepatocellular cancer (HCC) is highly resistant to chemotherapy and is associated with poor prognosis. Chronic hepatitis C virus (HCV) infection is a major cause of HCC. However, the effect of viral proteins in mediating chemosensitivity in tumor cells is unknown. We postulated that HCV viral proteins could modulate therapeutic responses by altering host cell microRNA (miRNA) expression.


METHODS
HepG2 malignant hepatocytes were stably transfected with full-length HCV genome (Hep-394) or an empty vector (Hep-SWX). MiRNA profiling was done by using a custom microarray, and the expression of selected miRNAs was validated by real-time PCR. Protein expression was assessed by Western blotting, whereas caspase activation was assessed by a luminometric assay.


RESULTS
The IC(50) to sorafenib was lower in Hep-394 compared with Hep-SWX control cells. Alterations in miRNA expression occurred with 10 miRNAs downregulated >2-fold and 23 miRNAs upregulated >2-fold in Hep-394 cells compared with controls. Of these, miR-193b was overexpressed by 5-fold in Hep-394 cells. miR-193b was predicted to target Mcl-1, an antiapoptotic protein that can modulate the response to sorafenib. The expression of Mcl-1 was decreased, and basal caspase-3/7 activity and poly ADP ribose polymerase cleavage were increased in Hep-394 cells compared with controls. Moreover, transfection with precursors to miR-193b decreased both Mcl-1 expression and the IC(50) to sorafenib.


CONCLUSIONS
Cellular expression of full-length HCV increases sensitivity to sorafenib by the miRNA-dependent modulation of Mcl-1 and apoptosis. Modulation of miRNA responses may be a useful strategy to enhance response to chemotherapy in HCC.
Braconi
Chiara
C
Department of Internal Medicine, Ohio State University Comprehensive Cancer Center, Columbus, Ohio, USA.
Valeri
Nicola
N
Gasparini
Pierluigi
P
Huang
Nianyuan
N
Taccioli
Cristian
C
Nuovo
Gerard
G
Suzuki
Tetsuro
T
Croce
Carlo Maria
CM
Patel
Tushar
T
D017209:Apoptosis; D001557:Benzenesulfonates / Q000627:therapeutic use*; D015972:Gene Expression Regulation, Neoplastic; D056945:Hep G2 Cells; D016174:Hepacivirus / Q000235:genetics / Q000378:metabolism*; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000821:virology*; D035683:MicroRNAs / Q000378:metabolism* / Q000494:pharmacology; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009536:Niacinamide / Q000031:analogs & derivatives; D010671:Phenylurea Compounds; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011725:Pyridines / Q000627:therapeutic use*; D000077157:Sorafenib; D014162:Transfection; D014764:Viral Proteins / Q000494:pharmacology*
D001557:Benzenesulfonates; C546818:MIRN193 microRNA, human; D035683:MicroRNAs; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D010671:Phenylurea Compounds; D019253:Proto-Oncogene Proteins c-bcl-2; D011725:Pyridines; D014764:Viral Proteins; D009536:Niacinamide; D000077157:Sorafenib