Effects of 660 nm and 810 nm Low-Power Diode Laser on Proliferation and Invasion of Oral Cancer Cells in Cell Culture Media

The effect of photobiomodulation on the radiosensitivity of cancer cells: a literature review

The goal of radiotherapy (RT) in cancer treatment is to destroy tumor tissue while preserving nearby healthy tissue. However, RT often causes adverse effects that significantly impact patients' quality of life. Tumor cells, which have high proliferation rates, are susceptible to radiation, especially during the G2 and mitosis phases of the cell cycle. Numerous studies have explored ways to enhance the Radiosensitivity of tumors to make RT more effective while minimizing harm to healthy cells. This review examines the potential use of photobiomodulation (PBM) as a radiosensitizer for cancer cells to improve the effectiveness and safety of radiotherapy. A literature search was conducted in the MEDLINE/PubMed and Google Scholar databases using keywords like "PBM, low-level light therapy, cancer cells, tumor cells, radiosensitizer, and ionizing radiation." Studies meeting the inclusion criteria were reviewed and analyzed. Several studies investigated PBM as a radiosensitizer for various cancer cell lines, including HeLa, HeLa Kyoto, A431, SCC9, and Cal 27. Most of these studies found that pre-exposure of cancer cells to PBM improved the effectiveness of radiation in destroying tumor cells. PBM is a promising, affordable, and noninvasive technique that could improve cancer treatment outcomes by increasing tumor sensitivity to radiation and reducing side effects. However, more research is needed to thoroughly assess the benefits of combining PBM with RT. Clinical trial number: not applicable. Clinical trial number: not applicable.

The effect of different parameters of low-level laser used in the treatment of oral mucositis, on the viability and apoptosis of oral squamous cell carcinoma cells: In vitro study

Oral mucositis is a complication of chemo/radiotherapy. To assess the impact of various power levels of diode-laser on the survival and expression of apoptosis-related genes in oral cancer cells, it is crucial to consider the potential existence of malignant cells within the treatment region and the reliance of laser effectiveness on its specific characteristics. Cal-27 cells were cultivated and exposed to a 660 nm-diode-laser at power levels of 20, 40, and 80 mW, alongside non-irradiated control cells. Viability and expression of Bax and Bcl-2 mRNA were assessed with Methyl Thiazolyl Tetrazolium (MTT) and Real-time Polymerase Chain Reaction (RT-PCR), respectively. The results were analyzed using one-way ANOVA and Tukey post-hoc test (p < 0.05). A significant reduction in viability was found only in the 20 mW group compared to controls (p = 0.001). Cell survival was significantly lower in cells receiving 20 mW laser than those treated with 40 and 80 mW (p < 0.05). None of the laser groups showed significant changes in BcL-2, but Bax was significantly lower in cells receiving 40 and 80 mW (p < 0.05), compared to controls. Laser irradiation at 660 nm (2 J/cm2, 30 s) significantly reduced the viability of oral cancer cells when using 20 mW power. These specifications align with the recommendation that the lowest possible laser dose should be applied for treating cancer patients. The exact mechanism of cell death following laser therapy with these specifications requires further investigation.

The Effect of Low-level Laser Therapy on VEGF, IL-6 Expression and Viability of Oral Squamous Cell Carcinoma Cells

Low-level laser therapy has shown successful results in the prevention and treatment of oral mucositis. One of the concerns about low-level lasers is their effects on remaining malignant cells in the area. Interleukin-6 is a multifunctional cytokine that plays an important role in a wide range of biologic activities in increasing tumor functions, decreasing survival, and resistance to chemo-radiotherapy. Vascular-endothelial growth factor increases tumor vascularization. It has been shown in the previous studies that LLLT can cause an increase of IL-6 and VEGF in some cells. The present thesis aims to study the effects of LLLT on IL-6 and VEGF expression, as well as cell viability on OSCC cells. Tumorigenic cells of an oral squamous cell carcinoma cell line were irradiated with 3 different diode lasers, and were compared to the control group (660nm- 200mW-4J/cm2, 810nm-200mW-4J/cm2, 940nm-200mW-4J/cm2). MTT assay, ELISA, and RT-PCR were used to measure cell viability, IL-6, and VEGF expression. Cell viability of all laser-irradiated groups was significantly lower than the control group. VEGF expression increased in laser-irradiated groups. This was only significant in the 810nm group. IL-6 protein secretion was significantly higher in all laser-irradiated groups compared to the control group.

[Low-level laser therapy in oncology - what's new? Analysis of 2018-2021 publications]

Low-level laser therapy (LLLT) is included in the Federal project «Fight against oncological diseases», which provides for equipping all specialized medical institutions in Russia with the appropriate devices until 2026.

PURPOSE OF THE STUDY

Publications analysis on the use of LLLT in oncology.

MATERIAL AND METHODS

To search for publications, databases and libraries were used: PubMed, Scopus, ResearchGate, Google Scholar, J-STAGE, eLibrary.ru for the period 2018-2021. For analysis, publications were selected that are of interest from the point of view of improving the methodology of LLLT, the prospects for the development of this method in the prevention, treatment and rehabilitation of patients. A total of 223 publications were found, including 39 reviews and meta-analyses, mostly in English (165) and Portuguese (41).

RESULTS AND DISCUSSION

The inclusion of LLLT in the ISOO/MASCC/ASCO recommendations for the treatment of complications such as mucositis, salivary gland hypofunction and xerostomia caused by non-surgical methods of treating cancer patients should be considered as a promising trend. An extremely low level of quality of LLLT techniques was noted, most often the replacement with meaningless «doses», «fluences» instead of the necessary parameters: wavelength, operating mode, power, frequency, exposure, etc. The use of only local illumination instead of systemic methods of LLLT does not allow obtaining the best results of treatment and prevention. Eliminating the shortcomings of treatment protocols with a focus on Russian experience, when laser blood illumination (intravenously or externally) and laser acupuncture are also necessarily carried out with local illumination of the lesion, will bring the effectiveness of LLLT to a qualitatively new, higher level.

808-nm Photobiomodulation Affects the Viability of a Head and Neck Squamous Carcinoma Cellular Model, Acting on Energy Metabolism and Oxidative Stress Production

Photobiomodulation (PBM) is a form of low-dose light therapy that acts through energy delivery from non-ionizing sources. During the recent two decades, there has been tremendous progress with PBM acceptance in medicine. However, PBM effects on potential stimulation of existing malignant or pre-malignant cells remain unknown. Thus, the primary endpoint was to assess the safety of PBM treatment parameters on head and neck squamous cell carcinoma (HNSCC) proliferation or survival. The secondary endpoint was to assess any putative anti-cancer effects of PBM treatments. Cell viability, energy metabolism, oxidative stress, and pro- and anti-apoptotic markers expression were investigated on a Human Head and Neck Squamous Cell Carcinoma cellular model (OHSU-974 FAcorr cell line). PBM therapy was administered through the 810 nm diode laser (GaAlAs) device (Garda Laser, 7024 Negrar, Verona, Italy) at the powers of 0, 0.25, 0.50, 0.75, 1.00, or 1.25 W in continuous wave (CW) mode for an exposure time of 60 s with a spot-size of 1 cm² and with a distance of 1.86 cm from the cells. Results showed that 810-nm PBM affected oxidative phosphorylation in OHSU-971 FAcorr, causing a metabolic switch to anaerobic glycolysis. In addition, PBM reduced the catalase activity, determining an unbalance between oxidative stress production and the antioxidant defenses, which could stimulate the pro-apoptotic cellular pathways. Our data, at the parameters investigated, suggest the safeness of PBM as a supportive cancer therapy. Pre-clinical and clinical studies are necessary to confirm the in vitro evidence.

Laser Photobiomodulation (PBM)-A Possible New Frontier for the Treatment of Oral Cancer: A Review of In Vitro and In Vivo Studies

The treatment of oral squamous cell carcinoma (OSCC) is particularly complex due to its aggressive behavior, location, the patient’s age, and its spread at diagnosis. In recent years, photobiomodulation (PBM) has been introduced in different medical fields; however, its application, in patients suffering from OSCC for palliative support or to induce analgesia, has been hotly debated due to the possibility that the cell growth stimuli induced by PBM could lead to a worsening of the lesions. The aim of this study is to review the literature to observe the available data investigating the effect of PBM on cancer cells in vitro and in vivo. A review was conducted on the PubMed and Scopus databases. A total of twelve studies met the inclusion criteria and were therefore included for quality assessment and data extraction. The analysis showed that the clinical use of PBM is still only partially understood and is, therefore, controversial. Some authors stated that it could be contraindicated for clinical use in patients suffering from SCC, while others noted that it could have beneficial effects. According to the data that emerged from this review, it is possible to hypothesize that there are possibilities for PBM to play a beneficial role in treating cancer patients, but further evidence about its clinical efficacy and the identification of protocols and correct dosages is still needed.