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

Abstract

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

ANXA6 Contributes to Radioresistance by Promoting Autophagy via Inhibiting the PI3K/AKT/mTOR Signaling Pathway in Nasopharyngeal Carcinoma

“…But the role of autophagy in radioresistance is still controversial. Wang et al (2013) hold the view that autophagy promotes radioresistance in pancreatic cancer cells, while Djavid et al (2017) concluded that the mobilization of autophagy could cause cell death through lysosomal activation, thus causing an enhancement of radiosensitivity in human cervical cancer cells. Our study demonstrated that autophagy inhibition increased the radiosensitivity of NPC cells and that there was a positive correlation between autophagy and radioresistance.…”

Red and near‐infrared light induces intracellular Ca2+ flux via the activation of glutamate N‐methyl‐D‐aspartate receptors

“…showing apoptotic signs after 20 min treatment with 20 J/cm 2 (Djavid et al, 2017). At the same time, other cancer cell lines demonstrated much more intensive proliferation as a result of light exposition.…”

Cellular transformations in near‐infrared light‐induced apoptosis in cancer cells revealed by label‐free CARS imaging

“…The PBM effect is also strongly dependent on the cell type: different cell lines demonstrate different responses to light irradiation . In particular, several studies showed that PBM can stimulate proliferation in some cell lines and cell death in others . For example, red and near infrared (NIR) light stimulate proliferation of human adipose‐derived stem cells and, at the same time, can effectively inhibit proliferation of fibroblasts .…”

“…Furthermore, NIR light was shown to significantly induce caspase‐3 activation and promote apoptosis in pancreatic cancer cells . It was also reported that both visible and infrared light demonstrated cytotoxic effects on human breast cancer cells , and lead to boosted radiosensitivity through enhancement of apoptosis in HeLa cells . As a result, low power laser irradiation in combination with radiotherapy can decrease the delivered radiation dose and, consequently, prevent some radiotherapy related side effects.…”

“…It is known that NIR light with different parameters is able to modulate intracellular ROS production that is actively involved in many intracellular processes, including lipid metabolism and apoptosis . There are plenty of studies showing a relation between PBM parameters and cell death rate , but the NIR light effect on lipid metabolic processes during the PBM‐induced apoptosis is not well described yet. In our study, we demonstrated the ability of NIR light to induce ROS‐mediated changes in lipid metabolism and promote cytoplasmic LDs formation in neuronal cells .…”