Modulating the dose-rate differently affects the responsiveness of human epithelial prostate- and mesenchymal rhabdomyosarcoma-cancer cell line to radiation

Abstract

Purpose: Radiation therapy (RT), by using ionizing radiation (IR), destroys cancer cells inducing DNA damage. Despite several studies are continuously performed to identify the best curative dose of IR, the role of dose-rate, IR delivered per unit of time, on tumor control is still largely unknown.

Materials and methods: Rhabdomyosarcoma (RMS) and prostate cancer (PCa) cell lines were irradiated with 2 or 10 Gy delivered at dose-rates of 1.5, 2.5, 5.5 and 10.1 Gy/min. Cell-survival rate and cell cycle distribution were evaluated by clonogenic assays and flow cytometry, respectively. The production of reactive oxygen species (ROS) was detected by cytometry. Quantitative polymerase chain reaction assessed the expression of anti-oxidant-related factors including NRF2, SODs, CAT and GPx4 and miRNAs (miR-22, -126, -210, -375, -146a, -34a). Annexin V and caspase-8, -9 and -3 activity were assessed to characterize cell death. Senescence was determined by assessing β-galactosidase (SA-β-gal) activity. Immunoblotting was performed to assess the expression/activation of: i) phosphorylated H2AX (γ-H2AX), markers of DNA double strand breaks (DSBs); ii) p19^Kip1/Cip1, p21^Waf1/Cip1 and p27^Kip1/Cip1, senescence-related-markers; iii) p62, LC3-I and LC3-II, regulators of autophagy; iv) ATM, RAD51, DNA-PKcs, Ku70 and Ku80, mediators of DSBs repair.

Results: Low dose-rate (LDR) more efficiently induced apoptosis and senescence in RMS while high dose-rate (HDR) necrosis in PCa. This paralleled with a lower ability of LDR-RMS and HDR-PCa irradiated cells to activate DSBs repair. Modulating the dose rate did not differently affect the anti-oxidant ability of cancer cells.

Conclusion: The present results indicate that a stronger cytotoxic effect was induced by modulating the dose-rate in a cancer cell-dependent manner, this suggesting that choose the dose-rate based on the individual patient’s tumor characteristics could be strategic for effective RT exposures.

Keywords:

• Rhabdomyosarcoma
• prostate cancer
• radiotherapy
• dose rate
• reactive oxygen species
• double-strand DNA breaks

Acknowledgements

The authors are grateful to ‘FIVA Confcommercio’ for supporting part of our work and Francesca Cicchetti to assist us during irradiation experiments.

Compliance with ethical standards

Ethical approval: Studies on animal models were not performed. This article does not contain any studies with human participants performed by any of the authors.

Informed consent: This article does not contain any studies with human participants performed by any of the authors.

Author contributions

FP, IP, VDN, IF and ADF planned experiments; CC, SC, PT, SO, SC, and MAM performed experiments; GDE, GP, MT, PDC, AR and AF planned radiation treatments, LM, FV, AF and RM analyze data; VT and FM wrote the paper.

Disclosure statement

The authors declare that they have no competing interests.

Additional information

Notes on contributors

Francesco Petragnano

Francesco Petragnano is a PhD student at University of L'Aquila, Italy, Laboratory of Pharmacology. He studies the molecular mechanisms of radio-resistance.

Ilaria Pietrantoni

Ilaria Pietrantoni is a Postdoc at University of L'Aquila, Italy, Laboratory of Pharmacology. She studies the molecular mechanisms of radio-resistance.

Valentina Di Nisio

Valentina Di Nisio is a PhD student at University of L'Aquila, Italy, Laboratory of Molecular biology. He studies the molecular mechanisms of radio-resistance.

Irene Fasciani

Irene Fasciani is a Postdoc at University of L'Aquila, Italy, Laboratory of Pharmacology. She studies the molecular mechanisms of radio-resistance.

Andrea Del Fattore

Andrea Del Fattore is the director of the Bone Physiopathology Unit genetics and rare diseases research area, Bambino Gesù Children's Hospital. He is also studying the molecular mechanisms of radio-resistance.

Carlo Capalbo

Carlo Capalbo is an Oncologist at University of Rome, Sapienza, Italy. He studies the molecular mechanisms of cancer onset and therapies-resistance.

Sara Cheleschi

Sara Cheleschi is a Postdoc at University of Siena, Italy, Laboratory of Rheumatology. She studies the molecular mechanisms regulating cellular response to oxidative stress.

Paolo Tini

Paolo Tini is a radiation therapist at University of Siena, Italy, Laboratory of Radiobiology. He studies the molecular mechanisms regulating cellular response to radiation.

Simone Orelli

Simone Orelli is specializing in radiation therapy at University of Rome, Sapienza. He studies the molecular mechanisms of radio-resistance.

Silvia Codenotti

Silvia Codenotti is a Postdoc at University of Brescia, Italy, Laboratory of Biochemistry. She studies the molecular mechanisms regulating rhabdomyosarcoma genesis.

Maria Antonietta Mazzei

Maria Antonietta Mazzei is a full professor of radiology therapist at University of Siena, Italy, Laboratory of Radiobiology. She studies the molecular mechanisms regulating cellular response to radiation.

Giuseppe D’Ermo

Giuseppe D'Ermo is a researcher in urology at University of Rome, Sapienza. He studies prostate cancer.

Gaetano Pannitteri

Gaetano Pannitteri is a researcher in cardiology at University of Rome, Sapienza. He studies the molecular mechanisms regulating cellular response to oxidative stress.

Mario Tombolini

Mario Tombolini is an otorinolaringoiatry at University of Rome, Sapienza. He studies the head and neck cancer.

Paola De Cesaris

Paola De Cesaris is an associate professor of histology at University of L'Aquila, Italy, Laboratory of Histology. She studies the molecular mechanisms regulating prostate cancer.

Anna Riccioli

Anna Riccioli is an associate professor of histology at University of Siena, Italy, Laboratory of Histology. She studies the molecular mechanisms regulating prostate cancer.

Antonio Filippini

Antonio Filippini is a full professor of histology at University of Siena, Italy, Laboratory of Histology. He studies the molecular mechanisms regulating prostate cancer.

Luisa Milazzo

Luisa Milazzo is a researcher at Istituto Superiore di sanità, Rome, Italy. She studies the molecular mechanisms regulating radioresistance.

Francesca Vulcano

Francesca Vulcano is a researcher at Istituto Superiore di Sanità, Rome, Italy. She studies the molecular mechanisms regulating radioresistance.

Alessandro Fanzani

Alessandro Fanzani is an associate professor at University of Brescia, Italy, Laboratory of Biochemistry. He studies the molecular mechanisms regulating rhabdomyosarcoma genesis.

Roberto Maggio

Roberto Maggio a full professor at University of L'Aquila, Italy, Laboratory of Pharmacology. He studies the molecular mechanisms of radio-resistance.

Francesco Marampon

Francesco Marampon is an associate professor of radiation therapy at University of Rome, Sapienza, Italy, Laboratory of Radiobiology. He studies the molecular mechanisms regulating radioresistance.

Vincenzo Tombolini

Vincenzo Tombolini is a full professor of radiation therapy at University of Rome, Sapienza, Italy, Laboratory of Radiobiology. He studies the molecular mechanisms regulating radioresistance.