ABSTRACT
The killing effect on S180 cells was studied using the combination of protoporphyrin IX and focused ultrasound at the frequency of 2.2 MHz and different intensities. Cell viability was determined by trypan blue exclusion test, morphology changes were evaluated by means of scanning electron microscopy and transmission electron microscopy after ultrasonic exposure. The results indicated that protoporphyrin IX(PPIX) alone showed no significant effect on S180 cells when compared with that of control group. Ultrasound alone and ultrasound combined with PPIX groups showed some anti-tumor effect, which became more noticeable as the ultrasound intensity and PPIX concentration increased, and when the concentration of PPIX increased to 120 microM, the ultrasound combined with PPIX exerted a more significant anti-tumor effect than did the ultrasound alone in the same experiment.
Subject(s)
Animals , Mice , Apoptosis , Radiation Effects , Mice, Inbred ICR , Photochemotherapy , Methods , Photosensitizing Agents , Pharmacology , Protoporphyrins , Pharmacology , Sarcoma 180 , Pathology , Therapeutics , Sonication , Tumor Cells, Cultured , UltrasonicsABSTRACT
Objective To study the cell killing effect on isolated sarcoma 180 cells by ultrasound activating Protoporphyrin IX and to explore its biological mechanism.Methods The sonodynamical effect was investigated on S180 tumor cells exposed to the combination of 120 mol/L protoporphyrin Ⅸ (PPⅨ) and focused ultrasound at the frequency of 2.2 MHz and an intensity of 3W/cm2. The livability of cells was evaluated by trypan blue staining. Scanning electron microscope (SEM) observation of the surface of cells was performed to evaluate the morphological changes induced by ultrasonic irradiation. The generation of oxygen free radicals in cell suspensions was immediately detected after treatment by the active oxygen detection kit. Oxidative stress was assessed by measuring the activities of key antioxidant enzymes (ie, Superoxide dismutase[SOD], Glutathione peroxidase [GSH-PX], Catalase [CAT]) in S180 cells after SDT.Results The cell damage rate of ultrasound combined with PPIX was significantly higher than that treated with ultrasound alone only, and PPIX alone had no killing effect on S180 cells. Enzymatic chemical methods showed the content of MDA significantly increased after treatment, while the activities of key antioxidant enzymes in tumor cells all decreased at different levels, and was associated to the generation of oxygen free radicals in cell suspension after treatment. Conclusion Oxygen free radical may play an important role inimproving the membrane lipid peroxidation, decreasing the activities of key antioxidant enzymes in cells, and the biological mechanism might be involved in mediating the killing effect of S180 cells in SDT.