MicroRNAs regulate methionine adenosyltransferase 1A expression in hepatocellular carcinoma
Heping Yang, … , Jose M. Mato, Shelly C. Lu
Heping Yang, … , Jose M. Mato, Shelly C. Lu
Published December 17, 2012
Citation Information: J Clin Invest. 2013;123(1):285-298. https://doi.org/10.1172/JCI63861.
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Research Article Oncology

MicroRNAs regulate methionine adenosyltransferase 1A expression in hepatocellular carcinoma

Abstract

MicroRNAs (miRNAs) and methionine adenosyltransferase 1A (MAT1A) are dysregulated in hepatocellular carcinoma (HCC), and reduced MAT1A expression correlates with worse HCC prognosis. Expression of miR-664, miR-485-3p, and miR-495, potential regulatory miRNAs of MAT1A, is increased in HCC. Knockdown of these miRNAs individually in Hep3B and HepG2 cells induced MAT1A expression, reduced growth, and increased apoptosis, while combined knockdown exerted additional effects on all parameters. Subcutaneous and intraparenchymal injection of Hep3B cells stably overexpressing each of this trio of miRNAs promoted tumorigenesis and metastasis in mice. Treatment with miRNA-664 (miR-664), miR-485-3p, and miR-495 siRNAs reduced tumor growth, invasion, and metastasis in an orthotopic liver cancer model. Blocking MAT1A induction significantly reduced the antitumorigenic effect of miR-495 siRNA, whereas maintaining MAT1A expression prevented miRNA-mediated enhancement of growth and metastasis. Knockdown of these miRNAs increased total and nuclear level of MAT1A protein, global CpG methylation, lin-28 homolog B (Caenorhabditis elegans) (LIN28B) promoter methylation, and reduced LIN28B expression. The opposite occurred with forced expression of these miRNAs. In conclusion, upregulation of miR-664, miR-485-3p, and miR-495 contributes to lower MAT1A expression in HCC, and enhanced tumorigenesis may provide potential targets for HCC therapy.

Authors

Heping Yang, Michele E. Cho, Tony W.H. Li, Hui Peng, Kwang Suk Ko, Jose M. Mato, Shelly C. Lu

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Figure 3

Increased cellular apoptosis and decreased cell growth in Hep3B cells by miRNA knockdown requires MAT1A induction.

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Increased cellular apoptosis and decreased cell growth in Hep3B cells by...
(A) Apoptosis rates were determined by Hoechst staining at 24, 48, and 72 hours after transient miRNA knockdown in Hep3B cells. *P < 0.01, **P < 0.05 vs. SC; †P < 0.05 vs. single or triple siRNA knockdown. n = 3 experiments, each with 12 determinations. (B) BrdU incorporation assay was measured at 24 hours after transient miRNA knockdown in Hep3B cells. *P < 0.05, **P < 0.01 vs. SC; †P < 0.05 vs. single or triple siRNA knockdown. n = 3 experiments, each with 8 determinations. (C) To determine the role of MAT1A induction on growth, Hep3B cells stably transfected with miR-664, miR-485-3p, and miR-495 siRNA or scramble siRNA (stable SC) were transiently transfected with MAT1A siRNA or SC, and BrdU incorporation and MAT1A protein levels were measured 24 hours later. *P < 0.05, **P < 0.01 vs. SC; †P < 0.05 vs. SC+MAT1Asi and each respective miRNA siRNA+SC. n = 3 experiments, each with 8 determinations for BrdU. Numbers below the Western blot represent mean densitometric values expressed as percentage of control.