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Pleiotropic effects of methionine adenosyltransferases deregulation as determinants of liver cancer progression and prognosis

Frau, Maddalena and Feo, Francesco and Pascale, Rosa Maria (2013) Pleiotropic effects of methionine adenosyltransferases deregulation as determinants of liver cancer progression and prognosis. Journal of Hepatology, Vol. 59 (4), p. 830-841. ISSN 0168-8278. Article.

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DOI: 10.1016/j.jhep.2013.04.031

Abstract

Downregulation of liver-specific MAT1A gene, encoding S-adenosylmethionine (SAM) synthesizing isozymes MATI/III, and upregulation of widely expressed MAT2A, encoding MATII isozyme, known as MAT1A:MAT2A switch, occurs in hepatocellular carcinoma (HCC). Being inhibited by its reaction product, MATII isoform upregulation cannot compensate for MATI/III decrease. Therefore, MAT1A:MAT2A switch contributes to decrease in SAM level in rodent and human hepatocarcinogenesis. SAM administration to carcinogen-treated rats prevents hepatocarcinogenesis, whereas MAT1A-KO mice, characterized by chronic SAM deficiency, exhibit macrovesicular steatosis, mononuclear cell infiltration in periportal areas, and HCC development. This review focuses upon the pleiotropic changes, induced by MAT1A/MAT2A switch, associated with HCC development. Epigenetic control of MATs expression occurs at transcriptional and post-transcriptional levels. In HCC cells, MAT1A/MAT2A switch is associated with global DNA hypomethylation, decrease in DNA repair, genomic instability, and signaling deregulation including c-MYC overexpression, rise in polyamine synthesis, upregulation of RAS/ERK, IKK/NF-kB, PI3K/AKT, and LKB1/AMPK axis. Furthermore, decrease in MAT1A expression and SAM levels results in increased HCC cell proliferation, cell survival, and microvascularization. All of these changes are reversed by SAM treatment in vivo or forced MAT1A overexpression or MAT2A inhibition in cultured HCC cells. In human HCC, MAT1A:MAT2A and MATI/III:MATII ratios correlate negatively with cell proliferation and genomic instability, and positively with apoptosis and global DNA methylation. This suggests that SAM decrease and MATs deregulation represent potential therapeutic targets for HCC. Finally, MATI/III:MATII ratio strongly predicts patients’ survival length suggesting that MAT1A:MAT2A expression ratio is a putative prognostic marker for human HCC.

Item Type:Article
ID Code:9227
Status:Published
Refereed:Yes
Uncontrolled Keywords:Hepatocarcinogenesis, methionine adenosyltransferase, S-adenosylmethionine, epigenetic regulation, signal transduction, progression, prognosis
Subjects:Area 06 - Scienze mediche > MED/04 Patologia generale
Divisions:001 Università di Sassari > 01-a Nuovi Dipartimenti dal 2012 > Medicina Clinica e Sperimentale
Publisher:Elsevier Science Ireland
ISSN:0168-8278
Deposited On:01 Oct 2013 12:11

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