NRF2 orchestrates the redox regulation induced by radiation therapy, sustaining embryonal and alveolar rhabdomyosarcoma cells radioresistance.

Abstract

PURPOSE:

Tumor cells generally exhibit higher levels of reactive oxygen species (ROS), however, when stressed, tumor cells can undergo a process of 'Redox Resetting' to acquire a new redox balance with stronger antioxidant systems that enable cancer cells to become resistant to radiation therapy (RT). Here, we describe how RT affects the oxidant/antioxidant balance in human embryonal (RD) and alveolar (RH30) rhabdomyosarcoma (RMS) cell lines, investigating on the molecular mechanisms involved.

METHODS:

Radiations were delivered using an x-6 MV photon linear accelerator and their effects were assessed by vitality and clonogenic assays. The expression of specific antioxidant-enzymes, such as Superoxide Dismutases (SODs), Catalase (CAT) and Glutathione Peroxidases 4 (GPx4), miRNAs (miR-22, -126, -210, -375, -146a, -34a) and the transcription factor NRF2 was analyzed by quantitative polymerase chain reaction (q-PCR) and western blotting. RNA interference experiments were performed to evaluate the role of NRF2.

RESULTS:

Doses of RT higher than 2 Gy significantly affected RMS clonogenic ability by increasing ROS production. RMS rapidly and efficiently brought back ROS levels by up-regulating the gene expression of antioxidant enzymes, miRNAs as well as of NRF2. Silencing of NRF2 restrained the RMS ability to counteract RT-induced ROS accumulation, antioxidant enzyme and miRNA expression and was able to increase the abundance of γ-H2AX, a biomarker of DNA damage, in RT-treated cells.

CONCLUSIONS:

Taken together, our data suggest the strategic role of oxidant/antioxidant balance in restraining the therapeutic efficiency of RT in RMS treatment and identify NRF2 as a new potential molecular target whose inhibition might represent a novel radiosensitizing therapeutic strategy for RMS clinical management.

• Authors: Francesco Marampon, Silvia Codenotti, Francesca Megiorni, Andrea Del Fattore, Simona Camero, Giovanni Luca Gravina, Claudio Festuccia, Daniela Musio, Francesca De Felice, Valerio Nardone, Anna Natalizia Santoro, Carlo Dominici, Alessandro Fanzani, Luigi Pirtoli, Antonella Fioravanti, Vincenzo Tombolini, Sara Cheleschi, Paolo Tini
• Journal: Journal of cancer research and clinical oncology (J Cancer Res Clin Oncol) Vol. 145 Issue 4 Pg. 881-893 (Apr 2019) ISSN: 1432-1335 [Electronic] Germany
• PMID: 30701326 (Publication Type: Journal Article)

Chemical References

• Antioxidants
• MicroRNAs
• NF-E2-Related Factor 2
• NFE2L2 protein, human
• RNA, Small Interfering
• Reactive Oxygen Species

Topics

• Antioxidants (metabolism)
• Cell Line, Tumor
• Dose-Response Relationship, Radiation
• Humans
• MicroRNAs (biosynthesis, genetics)
• NF-E2-Related Factor 2 (biosynthesis, genetics, metabolism)
• Oxidation-Reduction (radiation effects)
• RNA, Small Interfering (administration & dosage, genetics)
• Radiation Tolerance
• Reactive Oxygen Species (metabolism)
• Rhabdomyosarcoma, Alveolar (genetics, metabolism, radiotherapy)
• Rhabdomyosarcoma, Embryonal (genetics, metabolism, radiotherapy)
• Transfection
• Up-Regulation (radiation effects)