NUPR1 Silencing Induces Autophagy-Mediated Apoptosis in Multiple Myeloma Cells Through the PI3K/AKT/mTOR Pathway

DNA Cell Biol. 2020 Mar;39(3):368-378. doi: 10.1089/dna.2019.5196. Epub 2020 Jan 22.

Abstract

Nuclear protein 1 (NUPR1) is a stress-related small molecule and plays important roles in various tumors, including multiple myeloma (MM). Autophagy is essential for maintaining cellular homoeostasis in response to stress and, together with apoptosis, determines cell fate. Previous studies indicate that NUPR1 is involved in cancer progression of MM, but the underlying mechanisms have not been elucidated. In this study, we confirmed that NUPR1 and basal autophagy markers were highly expressed in the bone marrow of MM patients. The overexpression of NUPR1 was correlated with staging (both by Revised International Staging System [RISS] and Durie-Salmon [D-S] Staging System), levels of hemoglobin and calcium, and bone marrow plasma cell ratio in the MM patients. NUPR1 silencing reduced autophagy activities and induced apoptosis in U266 and RPMI 8226. We further observed a decrease in NUPR1 silencing-induced apoptosis in the presence of rapamycin, while an increase in apoptosis after chloroquine and 3-methyladenine treatment. Analysis of the mechanism indicated that PI3K/AKT/mTOR pathway was involved in autophagy-mediated apoptosis upon NUPR1 knockdown. In summary, our results demonstrate that NUPR1 silencing suppresses autophagy activities and induces autophagy-mediated apoptosis in MM cells through the PI3K/AKT/mTOR pathway, which exhibits potential as a treatment strategy for MM.

Keywords: NUPR1; PI3K/AKT/mTOR pathway; apoptosis; autophagy; multiple myeloma.

MeSH terms

  • Adenine / analogs & derivatives
  • Adenine / pharmacology
  • Apoptosis*
  • Autophagy*
  • Basic Helix-Loop-Helix Transcription Factors / genetics*
  • Basic Helix-Loop-Helix Transcription Factors / metabolism
  • Bone Marrow Cells / drug effects
  • Bone Marrow Cells / metabolism
  • Cell Line, Tumor
  • Chloroquine / pharmacology
  • Gene Silencing
  • Humans
  • Multiple Myeloma / genetics
  • Multiple Myeloma / metabolism*
  • Neoplasm Proteins / genetics*
  • Neoplasm Proteins / metabolism
  • Phosphatidylinositol 3-Kinases / metabolism
  • Proto-Oncogene Proteins c-akt / metabolism
  • Signal Transduction*
  • TOR Serine-Threonine Kinases / metabolism

Substances

  • Basic Helix-Loop-Helix Transcription Factors
  • NUPR1 protein, human
  • Neoplasm Proteins
  • 3-methyladenine
  • Chloroquine
  • Proto-Oncogene Proteins c-akt
  • TOR Serine-Threonine Kinases
  • Adenine