5-Aminolevulinic Acid-mediated Photodynamic Therapy For Human Oral Squamous Cell Carcinoma In Vitro And In Vivo

ObjectiveTo investigate the in vitro and in vivo effects of 5-aminolevulinic acid(5-ALA)-mediated photodynamic therapy against oral squamous cell carcinoma(OSCC)and preliminarily explore the possible mechanisms.Methods1.Human oral squamous cell carcinoma cells of tongue(SCC-25)were cultured in vitro.2.SCC-25 cells were divided into the control group and the experimental group,the production of protoporphyrin IX(PpIX)induced by 5-ALA in SCC-25 cells was detected using the flow cytometry.4.SCC-25 cells were divided into the control group,lazer irradiation alone group,5-ALA alone group and the experimental group(5-ALA with lazer irradiation),the cytotoxicity of 5-ALA combined with laser irradiation was evaluated in SCC-25 cells using the methyl thiazolyltetrazolium(MTT)assay and the induction effect of combination treatment on the cell apoptosis was assessed by the flow cytometry.5.The intracellular production of reactive oxygen species(ROS)triggered by5-ALA combined with laser irradiation was determined using a fluorescence probe method.6.A mouse OSCC xenograft model bearing SCC-25 tumor was built,and the mice were divided into control group(saline),5-ALA group(5-ALA along)and5-ALA combined with laser irradiation group.Antitumor effect of 5-ALA combined with laser irradiation was further measured.Results1.5-ALA induced the production of PpIX in SCC-25 cells in a drug concentration(0~150 μg/mL)-and incubation time(0~24 h)-dependent manner.When the 5-ALA concentration was 100 μg/mL,the intracellular PpIX production was in a relatively stable state.2.5-ALA(concentration of 5,10,25,50 and 100 μg/mL and incubation time of 12h)combined with laser irradiation notably inhibited the growth of SCC-25 cells and also induced significant cell apoptosis compared with the control group(P﹤0.05).3.After combination treatment(5-ALA of 5,10,25,50 and 100 μg/mL combined with laser irradiation),a large amount of ROS was produced in SCC-25 cells(P﹤0.05),which was in positive correlation with the intracellular PpIX content.4.5-ALA(concentration of 10,25 and 50 mg/kg)combined with laser irradiation greatly suppressed the tumor growth in SCC-25 tumor-bearing mices compared to the control group(P﹤0.05).Conclusions5-ALA-mediated photodynamic therapy can trigger the generation of intracellular ROS that has significant cytotoxicity and apoptosis induction effect,and thus inhibit the tumor growth both in vitro and in vivo.