الفهرس 
Introduction 1Only 14 pages are availabe for public view
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Abstract
Oral tongue squamous cell carcinoma is the most frequently occurring oral neoplasm accounting for 25-40% of all oral cancers. The incidence of OTSCC is rampantly increasing along with a high morbidity rate. The deleterious effects of conventional OTSCC treatments have led to a poor survival rate. This has urged researchers to concentrate their efforts on developing less invasive therapies that are selectively targeting neoplastic cells.
Nowadays, 5-ALA-PDT has grown much popularity lately in neoplasm treatment as it selectively targets neoplastic cells without affecting normal cells, thus minimizing any side effects resulting from damaging healthy cells. It employs the administration of an exogenous pro-photosensitizing agent named 5-ALA, which transforms into PpIX endogenous photosensitizer through the heme biosynthesis pathway. PpIX aggregates in abnormally proliferating neoplastic cells and generates high amounts of reactive oxygen species upon activation by a light source. This ends up selectively damaging neoplastic cell death while saving normal healthy cells from any damage.
The primary aim of the present study is to evaluate the effect of 5-ALA-PDT on tongue squamous cell carcinoma HNO-97 cell line, along with the effects of the separate applications of low-level laser and 5-ALA on these cells. The assessment was done by determining the mean viability percentage of HNO-97 cells with the aid of MTT cytotoxicity assay, qualitatively assessing apoptosis by DNA fragmentation, cytological evaluation of the occurring morphologic alterations as well as by more accurate distinguishing between cell death types that results from different treatments using Ann-V/PI double staining.
The mean viability percentages readings from the MTT cytotoxicity assay revealed that LLL irradiation, 5-ALA, 5-ALA-PDT, combination of LLLT and 5-ALA-PDT as well as cisplatin had a significant cytotoxic effect on HNO-97 cells where the percentages of viable cells significantly decreased in a dose-dependent manner when compared to untreated cells.
With regard to our DNA fragmentation results, DNA laddering was detected in 5-ALA, 5-ALA-PDT, combination of LLLT and 5-ALA-PDT and cisplatin groups where it was most distinct in the combination treatment group as well as positive control cisplatin group.
Referring to the results of the cytological assessment, it was obvious that the number of early and late apoptotic cells increased in all treatment groups. Additionally, few necrotic cells were detected and increased between the treatment groups but to a much lesser extent.
Concerning the Ann-V/PI double staining results, the results revealed that 5-ALA-PDT induced apoptosis of HNO-97 cells where the total rate of apoptosis increased in a dose-dependent manner. In addition, the combination treatment group of LLLT and 5-ALA-PDT increased the total rate of apoptosis in relation to the 5-ALA-PDT group.
The present study concluded that 5-ALA-PDT is effective in killing HNO-97 cells and that isolated applications of low-level laser and 5-ALA have a cytotoxic effect as well. Additionally, it was revealed that pre-radiating HNO-97 cells further enhanced the cytotoxic effect of 5-ALA-PDT primarily by reinforcing apoptotic cell death.