2. Academic Validation
  3. Synergistic anticancer activity of combined ATR and ribonucleotide reductase inhibition in Ewing's sarcoma cells

Synergistic anticancer activity of combined ATR and ribonucleotide reductase inhibition in Ewing's sarcoma cells

  • J Cancer Res Clin Oncol. 2023 Apr 25. doi: 10.1007/s00432-023-04804-0.
Max-Johann Sturm 1 2,  Julián Andrés Henao-Restrepo 3,  Sabine Becker 1 2,  Hans Proquitté 1,  James F Beck 1,  Jürgen Sonnemann 4 5
Affiliations

Affiliations

  • 1 Department of Paediatric and Adolescent Medicine, Jena University Hospital, Friedrich Schiller University Jena, Am Klinikum 1, 07747, Jena, Germany.
  • 2 Research Centre Lobeda, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany.
  • 3 Placenta Laboratory, Department of Obstetrics, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany.
  • 4 Department of Paediatric and Adolescent Medicine, Jena University Hospital, Friedrich Schiller University Jena, Am Klinikum 1, 07747, Jena, Germany. juergen.sonnemann@med.uni-jena.de.
  • 5 Research Centre Lobeda, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany. juergen.sonnemann@med.uni-jena.de.
PMID: 37097390 DOI: 10.1007/s00432-023-04804-0
Abstract

Purpose: Ewing's sarcoma is a highly malignant childhood tumour whose outcome has hardly changed over the past two decades despite numerous attempts at chemotherapy intensification. It is therefore essential to identify new treatment options. The present study was conducted to explore the effectiveness of combined inhibition of two promising targets, ATR and ribonucleotide reductase (RNR), in Ewing's sarcoma cells.

Methods: Effects of the ATR Inhibitor VE821 in combination with the RNR inhibitors triapine and didox were assessed in three Ewing's sarcoma cell lines with different TP53 status (WE-68, SK-ES-1, A673) by flow cytometric analysis of cell death, mitochondrial depolarisation and cell cycle distribution as well as by Caspase 3/7 activity determination, by immunoblotting and by real-time RT-PCR. Interactions between inhibitors were evaluated by combination index analysis.

Results: Single ATR or RNR inhibitor treatment produced small to moderate effects, while their combined treatment produced strong synergistic ones. ATR and RNR inhibitors elicited synergistic cell death and cooperated in inducing mitochondrial depolarisation, Caspase 3/7 activity and DNA fragmentation, evidencing an apoptotic form of cell death. All effects were independent of functional p53. In addition, VE821 in combination with triapine increased p53 level and induced p53 target gene expression (CDKN1A, BBC3) in p53 wild-type Ewing's sarcoma cells.

Conclusion: Our study reveals that combined targeting of ATR and RNR was effective against Ewing's sarcoma in vitro and thus rationalises an in vivo exploration into the potential of combining ATR and RNR inhibitors as a new strategy for the treatment of this challenging disease.

Keywords

ATR; Didox; Ewing’s sarcoma; Ribonucleotide reductase; Triapine; VE821.

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