Apoptosis

, Volume 19, Issue 1, pp 201–209

The putative BH3 mimetic S1 sensitizes leukemia to ABT-737 by increasing reactive oxygen species, inducing endoplasmic reticulum stress, and upregulating the BH3-only protein NOXA

  • Ryan Soderquist
  • Alexandre A. Pletnev
  • Alexey V. Danilov
  • Alan Eastman
Original Paper

DOI: 10.1007/s10495-013-0910-y

Cite this article as:
Soderquist, R., Pletnev, A.A., Danilov, A.V. et al. Apoptosis (2014) 19: 201. doi:10.1007/s10495-013-0910-y

Abstract

S1 is a putative BH3 mimetic proposed to inhibit BCL2 and MCL1 based on cell-free assays. However, we previously demonstrated that it failed to inhibit BCL2 or induce apoptosis in chronic lymphocytic leukemia (CLL) cells, which are dependent on BCL2 for survival. In contrast, we show here that S1 rapidly increases reactive oxygen species, initiates endoplasmic reticulum stress, and upregulates the BH3-only protein NOXA. The BCL2 inhibitors, ABT-737, ABT-263, and ABT-199, have demonstrated pro-apoptotic efficacy in cell lines, while ABT-263 and ABT-199 have demonstrated efficacy in early clinical trials. Resistance to these inhibitors arises from the upregulation of anti-apoptotic factors, such as MCL1, BFL1, and BCLXL. This resistance can be induced by co-culturing CLL cells on a stromal cell line that mimics the microenvironment found in patients. Since NOXA can inhibit MCL1, BFL1, and BCLXL, we hypothesized that S1 may overcome resistance to ABT-737. Here we demonstrate that S1 induces NOXA-dependent sensitization to ABT-737 in a human promyelocytic leukemia cell line (NB4). Furthermore, S1 sensitized CLL cells to ABT-737 ex vivo, and overcame resistance to ABT-737 induced by co-culturing CLL cells with stroma.

Keywords

BCL2MCL1BCLXLNOXAReactive oxygen speciesATF3

Supplementary material

10495_2013_910_MOESM1_ESM.pdf (724 kb)
Supplementary material 1 (PDF 723 kb)

Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  • Ryan Soderquist
    • 1
  • Alexandre A. Pletnev
    • 2
  • Alexey V. Danilov
    • 3
  • Alan Eastman
    • 1
  1. 1.Department of Pharmacology and ToxicologyNorris Cotton Cancer Center, Geisel School of Medicine at DartmouthLebanonUSA
  2. 2.Department of ChemistryDartmouth CollegeHanoverUSA
  3. 3.Department of MedicineNorris Cotton Cancer Center, Geisel School of Medicine at DartmouthLebanonUSA