Role of MicroRNA-155 at Early Stages of... : Hepatology (original) (raw)

Hepatobiliary Malignancies

Role of MicroRNA-155 at Early Stages of Hepatocarcinogenesis Induced by Choline-Deficient and Amino Acid–Defined Diet in C57BL/6 Mice†

Wang, Bo1; Majumder, Sarmila1,2; Nuovo, Gerard2,3; Kutay, Huban1; Volinia, Stefano2,4; Patel, Tushar2,5; Schmittgen, Thomas D.2,6; Croce, Carlo2,4; Ghoshal, Kalpana1,2,*,‡; Jacob, Samson T.1,2,*,‡

1 Department of Molecular and Cellular Biochemistry, Ohio State University, Columbus, OH

2 Comprehensive Cancer Center, Ohio State University, Columbus, OH

3 Department of Pathology, Ohio State University, Columbus, OH

4 Department of Molecular Virology, Immunology and Medical Genetics, Ohio State University, Columbus, OH

5 Department of Gastroenterology and Hepatology, Ohio State University, Columbus, OH

6 Department of Pharmacy and Ohio State University, Columbus, OH

*Address reprint requests to: 420 West 12th Avenue, Columbus, OH 43210

E-mail:[email protected]

Received 20 March 2009; Accepted 17 May 2009.

Published online in Wiley InterScience (www.interscience.wiley.com)..

Grant sponsor: National Institutes of Health; Grant Numbers: CA086978 CA101956.

†Potential conflict of interest: Nothing to report.

‡fax: 614-688-5600

Additional Supporting Information may be found in the online version of this article.

Abstract

MicroRNAs (miRs) are conserved, small (20-25 nucleotide) noncoding RNAs that negatively regulate expression of messenger RNAs (mRNAs) at the posttranscriptional level. Aberrant expression of certain microRNAs plays a causal role in tumorigenesis. Here, we report identification of hepatic microRNAs that are dysregulated at early stages of feeding C57BL/6 mice choline-deficient and amino acid–defined (CDAA) diet that is known to promote nonalcoholic steatohepatitis (NASH)-induced hepatocarcinogenesis after 84 weeks. Microarray analysis identified 30 hepatic microRNAs that are significantly ( P ≤ 0.01) altered in mice fed CDAA diet for 6, 18, 32, and 65 weeks compared with those fed choline-sufficient and amino acid–defined (CSAA) diet. Real-time reverse transcription polymerase chain reaction (RT-PCR) analysis demonstrated up-regulation of oncogenic miR-155, miR-221/222, and miR-21 and down-regulation of the most abundant liver-specific miR-122 at early stages of hepatocarcinogenesis. Western blot analysis showed reduced expression of hepatic phosphatase and tensin homolog (PTEN) and CCAAT/enhancer binding protein beta (C/EBPβ), respective targets of miR-21 and miR-155, in these mice at early stages. DNA binding activity of nuclear factor kappa B (NF-κB) that transactivates miR-155 gene was significantly ( P = 0.002) elevated in the liver nuclear extract of mice fed CDAA diet. Furthermore, the expression of miR-155, as measured by in situ hybridization and real-time RT-PCR, correlated with diet-induced histopathological changes in the liver. Ectopic expression of miR-155 promoted growth of hepatocellular carcinoma (HCC) cells, whereas its depletion inhibited cell growth. Notably, miR-155 was significantly ( P = 0.0004) up-regulated in primary human HCCs with a concomitant decrease ( P = 0.02) in C/EBPβ level compared with matching liver tissues.

Conclusion:

Temporal changes in microRNA profile occur at early stages of CDAA diet-induced hepatocarcinogenesis. Reciprocal regulation of specific oncomirs and their tumor suppressor targets implicate their role in NASH-induced hepatocarcinogenesis and suggest their use in the diagnosis, prognosis, and therapy of liver cancer. (Hepatology 2009.)