MicroRNA silencing of tumor suppressor DLC-1 promotes efficient hepatitis C virus replication in primary human hepatocytes.
MicroRNAs (miRNAs) are approximately 22-nucleotide noncoding RNAs that constitute silencers of target gene expression. Aberrant expression of miRNA has been linked to a variety of cancers, including hepatocellular carcinoma (HCC). Hepatitis C virus (HCV) infection is considered a major cause of chronic liver disease and HCC, although the mechanism of virus infection-associated hepatocarcinogenesis remains unclear. We report a direct role of miRNAs induced in HCV-infected primary human hepatocytes that target the tumor suppressor gene DLC-1 (a Rho GTPase-activating protein), which is frequently deleted in HCC, and other solid human tumors. MicroRNA miR-141 that targets DLC-1 was accentuated in cells infected with HCV genotypes 1a, 1b, and 2a. We present several lines of evidence that efficient HCV replication requires miR-141-mediated suppression of DLC-1. An increase in miR-141 correlated with the inhibition of DLC-1 protein in HCV-infected cells. Depletion of miR-141 with oligonucleotides complementary to the miRNAs inhibited virus replication, whereas artificially increased levels of intracellular miR-141 enhanced HCV replication. HCV-infected hepatocytes showed enhanced cell proliferation that can be countered by overexpression of DLC-1.


CONCLUSIONS
The collective results of this study suggest a novel mechanism of HCV infection-associated miRNA-mediated regulation of a tumor suppressor protein that has the ability to influence cell proliferation and HCV infection-mediated liver cancer.
Department of Biochemistry and Molecular Biology, The George Washington University, Washington, DC 20037, USA.
Krishna
K
Banaudha
Michael
M
Kaliszewski
Tamara
T
Korolnek
Liliana
L
Florea
Man Lung
ML
Yeung
Kuan-Teh
KT
Jeang
Ajit
A
Kumar
D002478:Cells, Cultured; D018920:Coculture Techniques; D020690:GTPase-Activating Proteins / Q000235:genetics*; D016174:Hepacivirus / Q000502:physiology*; D022781:Hepatocytes / Q000821:virology; D006801:Humans; D035683:MicroRNAs / Q000494:pharmacology / Q000502:physiology*; D034622:RNA Interference / Q000502:physiology; D025521:Tumor Suppressor Proteins / Q000235:genetics*; D014779:Virus Replication / Q000187:drug effects* / Q000235:genetics
C112352:DLC1 protein, human; D020690:GTPase-Activating Proteins; C533895:MIRN141 microRNA, human; C533896:MIRN200 microRNA, human; D035683:MicroRNAs; D025521:Tumor Suppressor Proteins