Combination of a novel photosensitizer DTPP with 650 nm laser results in efficient apoptosis, arresting cell cycle and cytoskeleton protein changes in lung cancer A549 cells

Photodynamic therapy (PDT) using photosensitized reaction to produce cytotoxicity was used for cancer therapy in recent years. To study the effectiveness of PDT mediated by a novel photosensitizer (PS), DTPP 5-(4′-(2″-dicarboxymethylamino)acetamidophenyl)-10, 15, 20-triphenylporphyrin, on lung cancer A549 cell lines in vitro, DTPP was employed in different concentrations (2, 4, 6, 8, 10, 12, 15, 20, 25, and 30 μg/ml) and combined with 650 nm laser of different power densities (0.6, 1.2, 2.4, 4.8, 7.2, and 9.6 J/cm²) that resulted in obvious inhibition of cell proliferation and apoptosis. Results showed that cell survival rates have a dependent relationship with time and PS concentrations and no significant cytotoxicity was induced by DTPP itself. Apoptosis and cell cycle S arrest were observed; cytoskeleton morphologic observation revealed collapse, sparkling, and shrunken shapes. Apoptosis-related protein caspase-3 overexpression was detected while caspase-9, bcl-2, and cytoskeleton protein beta-catenin were in low levels of expression than the control. Cleavage of beta-catenin by caspase-3 or other proteases from the lysosome might be the main reason for the cytoskeleton collapse as beta-tubulin and actin were at a stable level 12 h after PDT. This paper gives a better understanding of the effectiveness of DTPP-mediated PDT in lung cancer A549 cells both with regard to dosimetry and apoptosis changes.