ERK Activation Globally Downregulates miRNAs through Phosphorylating Exportin-5

Cancer Cell. 2016 Nov 14;30(5):723-736. doi: 10.1016/j.ccell.2016.10.001.

Abstract

MicroRNAs (miRNA) are mostly downregulated in cancer. However, the mechanism underlying this phenomenon and the precise consequence in tumorigenesis remain obscure. Here we show that ERK suppresses pre-miRNA export from the nucleus through phosphorylation of exportin-5 (XPO5) at T345/S416/S497. After phosphorylation by ERK, conformation of XPO5 is altered by prolyl isomerase Pin1, resulting in reduction of pre-miRNA loading. In liver cancer, the ERK-mediated XPO5 suppression reduces miR-122, increases microtubule dynamics, and results in tumor development and drug resistance. Analysis of clinical specimens further showed that XPO5 phosphorylation is associated with poor prognosis for liver cancer patients. Our study reveals a function of ERK in miRNA biogenesis and suggests that modulation of miRNA export has potential clinical implications.

Keywords: ERK; Exportin-5; Pin1; drug resistance; global downregulation; liver cancer; miR-122; miRNA; microtubule; nuclear export.

MeSH terms

  • Carcinoma, Hepatocellular / genetics
  • Carcinoma, Hepatocellular / metabolism
  • Carcinoma, Hepatocellular / pathology*
  • Down-Regulation
  • Drug Resistance, Neoplasm
  • Extracellular Signal-Regulated MAP Kinases / metabolism*
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Karyopherins / chemistry
  • Karyopherins / metabolism*
  • Liver Neoplasms / genetics
  • Liver Neoplasms / metabolism
  • Liver Neoplasms / pathology*
  • MicroRNAs / genetics*
  • NIMA-Interacting Peptidylprolyl Isomerase / metabolism*
  • Phosphorylation
  • Prognosis
  • Protein Conformation

Substances

  • Karyopherins
  • MIRN122 microRNA, human
  • MicroRNAs
  • NIMA-Interacting Peptidylprolyl Isomerase
  • XPO5 protein, human
  • Extracellular Signal-Regulated MAP Kinases
  • PIN1 protein, human