NLS-RARα Inhibits the Effects of All-trans Retinoic Acid on NB4 Cells by Interacting with P38α MAPK

Int J Med Sci. 2016 Jul 18;13(8):611-9. doi: 10.7150/ijms.15374. eCollection 2016.

Abstract

Nuclear localization signal retinoic acid receptor alpha(NLS-RARα), which forms from the cleavage of promyelocytic leukemia-retinoic acid receptor alpha(PML-RARα) protein by neutrophil elastase(NE), possesses an important role in the occurrence and development of acute promyelocytic leukemia(APL). However, the potential mechanism underlying the effects of NLS-RARα on APL is still not entirely clear. Here, we investigated the effects of NLS-RARα on APL NB4 cells and its mechanism. We found that all-trans retinoic acid(ATRA) could promote differentiation while inhibit proliferation of APL NB4 cells via upregulating the expression of phosphorylated p38α mitogen-activated protein kinase(p-p38α MAPK). We also found that NLS-RARα could inhibit differentiation while accelerate proliferation of NB4 cells via downregulating the expression of p-p38α protein in the presence of ATRA. Furthermore, immunofluorescence and co-immunoprecipitation assays confirmed NLS-RARα interacted with p38α protein directly. Finally, application of PD169316, an inhibitor of p38α protein, suggested that recruitment p38α-combinded NLS-RARα by ATRA eventually caused activation of p38α protein. In summary, our study demonstrated that ATRA cound promote differentiation while inhibit proliferation of APL NB4 cells via activating p38α protein after recruiting p38α-combinded NLS-RARα, while NLS-RARα could inhibit the effects of ATRA in the process.

Keywords: NB4 cells; acute promyelocytic leukemia; all-trans retinoic acid; nuclear localization signal retinoic acid receptor alpha; p38α MAPK..

MeSH terms

  • Cell Differentiation / drug effects
  • Cell Differentiation / genetics
  • Cell Line, Tumor
  • Drug Resistance, Neoplasm / genetics
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • Imidazoles / administration & dosage
  • Leukemia, Promyelocytic, Acute / drug therapy
  • Leukemia, Promyelocytic, Acute / genetics*
  • Leukemia, Promyelocytic, Acute / pathology
  • Nuclear Localization Signals / genetics*
  • Nuclear Localization Signals / metabolism
  • Oncogene Proteins, Fusion / genetics
  • Retinoic Acid Receptor alpha / genetics*
  • Retinoic Acid Receptor alpha / metabolism
  • Tretinoin / administration & dosage
  • p38 Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • p38 Mitogen-Activated Protein Kinases / biosynthesis*
  • p38 Mitogen-Activated Protein Kinases / genetics

Substances

  • Imidazoles
  • Nuclear Localization Signals
  • Oncogene Proteins, Fusion
  • RARA protein, human
  • Retinoic Acid Receptor alpha
  • promyelocytic leukemia-retinoic acid receptor alpha fusion oncoprotein
  • Tretinoin
  • p38 Mitogen-Activated Protein Kinases
  • 2-(4-nitrophenyl)-4-(4-fluorophenyl)-5-(4-pyridinyl)-1H-imidazole