Effects and mechanisms of photobiomodulation on the behavior of tumor cells in two-dimensional and three-dimensional cultures

Abstract

Head and neck tumors are among the most common malignant neoplasms worldwide. Current forms of treatment are associated with acute, long-term morbidity and compromised quality of life for patients. Photobiomodulation (PBMT) is used as a tool in the supportive treatment of cancer patients. However, the influence of PBMT on tumor cells is not fully understood and raises questions regarding the safety of using PBMT in cancer patients. This study aims to evaluate the influence of photobiomodulation on head and neck cancer cells under 2D and 3D in vitro conditions. The present study will be divided into ten groups, five for the 2D monolayer experiment and five for the 3D experiment. The number of proliferating cells and the total number of cells will be quantified by ImageJ® software to determine the percentage of proliferating cells in the cancellous hydrogel. In vitro 3D multiphoton fluorescence imaging will be acquired using an inverted Olympus FV1000 MPE microscope equipped with Spectra-Physics DeepSee Ti: Sapphire LASER. To assess cell viability, the assay of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) will be used to measure the activity of mitochondrial dehydrogenase. Normality will be assessed using the Shapiro Wilk test and, for comparison between groups, the analysis of variance will be performed using the two-factor ANOVA test. In the presence of a significant difference (p <0.05), the Tukey test will be applied. GraphPad Prism® 7.0 software (San Diego, CA, USA) will be used to perform the analyses. (AU)