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J Biophotonics. 2017 Dec;10(12):1732-1742. doi: 10.1002/jbio.201700004. Epub 2017 May 2.

Photobiomodulation leads to enhanced radiosensitivity through induction of apoptosis and autophagy in human cervical cancer cells.

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Medical Laser Research Center, Academic Center for Education, Culture, and Research (ACECR), Tehran, Iran.
Laboratory of Biophysics and Molecular Biology, Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Iran.
Radiotherapy Department, Firoozgar Hospital, Iran University of Medical Sciences., Tehran, Iran.
Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, USA.
Department of Dermatology, Harvard Medical School, Boston, Massachusetts, USA, Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts, USA.


The radiomodulatory effect of photobiomodulation (PBM) has recently been studied in cancer cells. The aim of this study was to investigate cellular mechanisms involved in the X-ray radiosensitivity of HeLa cells pre-exposed to PBM. HeLa cells were irradiated with 685 nm laser at different energy densities prior to X-ray ionizing radiation. After irradiation, clonogenic cell survival, cell death due to apoptosis and autophagy were determined. Levels of intracellular reactive oxygen species (ROS), DNA damage and, cell cycle distribution after PBM were measured. PBM at different energy densities (5-20 J/cm2 ) was not cytotoxic. However, HeLa cells pre-exposed to 20 J/cm2 showed enhanced inhibition of colony formation following ionizing radiation. Enhanced radiosensitivity was due to increased oxidative stress, DNA damage, and radiation-induced apoptosis and autophagy. These results suggest that 685 nm PBM at a higher energy density could possibly be a promising radiosensitizing agent in cervical cancer, to decrease the radiation dose delivered, and therefore prevent the side-effects that are associated with cancer radiotherapy.


autophagy; cervical cancer cells; ionizing radiation; low-level laser therapy; photobiomodulation; radiosensitization

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