The Synergistic Cytotoxic Effect of Low-Level Laser Therapy and 5-Aminolevulinic Acid-Mediated Photodynamic Therapy on Tongue Squamous Cell Carcinoma Cell Line

Abstract

Introduction: Nowadays, the global burden of cancer has grown substantially, endangering the public health. Thus, the discovery of innovative therapeutic modalities with the fewest adverse effects that improve patient quality of life has become compulsory. Research about the significance of utilizing photodynamic therapy (PDT) and enhancing its effect in neoplasms treatment has become crucial to fully comprehend its impact on neoplastic cells of various origins before adopting it into clinical practice. Aim of the Work: The current study aimed at investigating the cytotoxic effect of 5-aminolevulinic acid-mediated photodynamic therapy (5-ALA-PDT) on human tongue squamous cell carcinoma (HNO-97) cells and assessing the possible enhancement of its efficacy by combining it with low-level laser therapy (LLLT). Material and Methods: The current study was divided into five groups; control group, 5-ALA only group, LLLT only group, 5-ALA-PDT group and a combination of LLLT and 5-ALA-PDT group. Two concentrations of 5-ALA were utilized throughout the experiment. To investigate the effects of the various treatments, the evaluation was done utilizing MTT cytotoxicity assay to assess the viability of different treatments, DNA fragmentation assay to evaluate apoptosis qualitatively, examination of cytological alterations by H&E stain and Ann-V/PI double staining to differentiate between different types of cell death. Statistical analysis was done using ANOVA, multiple comparisons post hoc Tukey test and unpaired t-test for each variable of the results. Results: MTT assay results showed a significant decrease in the mean viability percentages of all studied groups and subgroups in comparison to the untreated negative control subgroup and a non-significant decline of that of the combination treatment subgroups when compared to 5-ALA-PDT subgroups. DNA fragmentation, cytological examination and Ann-V/PI results revealed an increase in the apoptosis rate across all treatment groups. Conclusion: 5-ALA-PDT had an obvious cytotoxic effect on HNO-97 cells that can be further reinforced by combining it with LLLT.