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Updated: Jul 19, 2026

Studying RNA Interactors of Protein Kinase RNA-Activated during the Mammalian Cell Cycle
10:05

Studying RNA Interactors of Protein Kinase RNA-Activated during the Mammalian Cell Cycle

Published on: March 5, 2019

Double-stranded RNA-dependent protein kinase is involved in 2-methoxyestradiol-mediated cell death of osteosarcoma

Kristen L Shogren1, Russell T Turner, Michael J Yaszemski

  • 1Department of Orthopedics, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.

Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research
|October 4, 2006
PubMed
Abstract

Insights

2-Methoxyestradiol (2-ME) activates the protein kinase R (PKR) in human osteosarcoma cells, leading to cell death. This PKR activation is essential for 2-ME-mediated apoptosis, independent of interferon signaling.

Area of Science:

  • Oncology
  • Molecular Biology
  • Biochemistry

Background:

  • Osteosarcoma is a common adolescent bone cancer.
  • 2-Methoxyestradiol (2-ME), an estradiol metabolite, induces apoptosis and interferon gene expression in osteosarcoma cells.
  • The role of protein kinase R (PKR) in 2-ME-induced cell death was investigated.

Purpose of the Study:

  • To elucidate the involvement of interferon-regulated PKR in 2-ME-mediated apoptosis of human osteosarcoma cells.
  • To determine if PKR activation is necessary for 2-ME-induced cell death.
  • To investigate the mechanism of PKR regulation by 2-ME.

Main Methods:

  • Western blot analysis to assess PKR protein and phosphorylation levels.
  • Cell survival and apoptosis assays (trypan blue exclusion, Hoechst dye).
  • Transient transfection with dominant-negative PKR mutants.

Main Results:

  • 2-ME treatment increased PKR protein levels and kinase activity (autophosphorylation, eIF-2alpha phosphorylation) in MG63 cells.
  • PKR activation by 2-ME was essential for osteosarcoma cell death, as indicated by inhibition with PKR inhibitors (2-AP) and dominant-negative PKR mutants.
  • 2-ME-mediated PKR regulation and cell death occurred independently of interferon gene expression.

Conclusions:

  • PKR is activated by 2-ME in human osteosarcoma cells.
  • PKR activation is a critical mediator of 2-ME-induced apoptosis.
  • 2-ME targets PKR independently of interferon signaling to induce osteosarcoma cell death.

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