Migratory Dynamics in Oral Squamous Cell Carcinoma Cells Following Photobiomodulation

Objectives: Photobiomodulation therapy (PBMT) is used to treat oral mucositis via a regenerative process that causes proliferation and migration of oral keratinocytes. Numerous applications of PBMT in head and neck oncology are being evaluated. A key concern is if PBMT will increase invasive qualities of cancer cells. We hypothesized that PBMT will stimulate cancer cell migration in two-dimensional analysis.
Methods: Scratch assays were utilized to assess cellular migration in SCC-25. Cells were plated at confluence in triplicate wells in 24-well plates. Cells were pretreated for either one or two days with a 660 nm low-level laser probe at 75 mW, 3 J/cm² energy density at 24 hr intervals. Scratches were made using a sterile pipette tip for each group followed by a final PBMT treatment. Cells were then grown for 24 hr and measurements for scratch closure were recorded. For every well of each triplicate, 3 regions of the scratch were recorded and 3 distances for each region were calculated totaling 27 measurements per group. Experiments were performed 3 independent times and analyzed using unpaired student t-test analysis. Immunofluorescence of actin and vimentin was also performed.
Results: For both 24 and 48 hr PBMT pretreatment groups, no changes to scratch closure were noted when PBMT treated cells were compared to control conditions. For immunofluorescent analysis, filamentous and cortical actin staining and vimentin fluorescence patterns were observed in both control and PBMT treatment groups with no differences noted.
Conclusions: This study found minimal dose-response relationship with PBMT directly on cell migration of SCC-25 cells. The lack of obvious changes to cytoskeletal proteins and migratory potential in PBMT treated groups could reflect the Arndt-Schultz law effect indicating that evaluating moderate PBMT dose densities may yield no results. Additional PBMT dosing parameters will be evaluated in future studies.