Photodynamic therapy (PDT) is based on preferential accumulation of a photosensitizer in tumor tissue. Subsequent local activation of the agent by visible light induces tumor destruction. At the present, various classes of sensitizers are presently in clinical use or in stages of development in biological media. The aim of the study is to evaluate for first time the photodynamic effects of P-C60, a dyad with high ability to form photoinduced charge-separated states, in a human
carcinoma cell line (Hep-2). P-C60 is innocuous in dark until concentration 1 µM and 24 h of incubation. The sensitizer is rapidly incorporated in the cells (<4 h) and the uptake tends to a saturation value between 4 and 24 h (~1,5 nmol/106 cells). After irradiation, the cell viability was depending of light doses used. A high photocytotoxic effect (80%) was observed with 54 Jcm-2. Moreover, the dyad keeps a high photoactivity even under argon atmosphere. Thus, two oxidative mechanisms are considered to be implicated in the photodamage of cells. The changes in the cellular morphology were analyzed using microscopy of fluorescence. Irradiation for 54 Jcm-2 produced chromatin nucleosomal fragmentation, characteristic of apoptosis. These results were confirmed by agarose gel electrophoresis, showing
an internucleosomal fragmentation of the chromatin. These studies suggest that the dyad P-C60 offer a promising molecular architecture for photosensitizer agents with potential applications in cell inactivation by PDT.
Grants: CONICET, FONCYT and SECYT UNRC.
