Roles of M6A Regulators in Hepatocellular Carcinoma: Promotion or Suppression

Hepatocellular carcinoma (HCC) is the sixth globally diagnosed cancer with a poor prognosis. Although the pathological factors of hepatocellular carcinoma are well elucidated, the underlying molecular mechanisms remain unclear. N6-methyladenosine (m6A) is an adenosine methylation occurring at the N6 site, which is the most prevalent modification of eukaryotic mRNA. Recent studies have shown that m6A can regulate gene expression, thus modulating the processes of cell self-renewal, differentiation, and apoptosis. The methyls in m6A are installed by methyltransferases ("writers"), removed by demethylases ("erasers") and recognized by m6A-binding proteins ("readers"). In this review, we discuss the roles of above regulators in the progression and prognosis of HCC, and summarize the clinical association between m6A modification and hepatocellular carcinoma, so as to provide more valuable information for clinical treatment.

Epitranscriptomic(N6-methyladenosine) Modification of Viral RNA and Virus-Host Interactions

N6-methyladenosine (m⁶A) is the most prevalent and internal modification of eukaryotic mRNA. Multiple m⁶A methylation sites have been identified in the viral RNA genome and transcripts of DNA viruses in recent years. m⁶A modification is involved in all the phases of RNA metabolism, including RNA stability, splicing, nuclear exporting, RNA folding, translational modulation, and RNA degradation. Three protein groups, methyltransferases (m⁶A-writers), demethylases (m⁶A-erasers), and m⁶A-binding proteins (m⁶A-readers) regulate this dynamic reversible process. Here, we have reviewed the role of m⁶A modification dictating viral replication, morphogenesis, life cycle, and its contribution to disease progression. A better understanding of the m⁶A methylation process during viral pathogenesis is required to reveal novel approaches to combat the virus-associated diseases.