Chlorin e6 derivative radachlorin mainly accumulates in mitochondria, lysosome and endoplasmic reticulum and shows high affinity toward tumors in nude mice in photodynamic therapy

The efficacy of photodynamic therapy (PDT) depends upon the amount of photosensitizer accumulated in the malignant tissues. Radachlorin is a popular photosensitizer used in photodynamic therapy to treat various types of cancer. In this study, we have studied the main organelles responsible for the accumulation of radachlorin in human anaplastic thyroid cancer in vitro and in vivo. The optimal time window for uptake and clearance of radachlorin also was studied. Confocal microscopic images confirmed that the radachlorin is mainly acquired by mitochondria and partially by lysosome and endoplasmic reticulum. Studies also showed that the maximum amount of radachlorin was accumulated within 3-6 h after the treatment. Radachlorin also showed a higher affinity toward malignant tumors compared to the other organs in mice xenograft model. Uptake of radachlorin reached an optimum amount within 6 h and most of the radachlorins were also cleared from the body in next 48 h. Therefore, detailed information regarding exact accumulation sites and a time window in which maximum amount of drug is accumulated and cleared were obtained by this study. Hence, not only the efficacy of the treatment can be increased but the phototoxicity after the treatment also can be controlled.

The effects of photodynamic therapy with Photodithazine on HPV 16 E6/E7 associated cervical cancer model

Photodynamic therapy (PDT) is a promising treatment for cancer that has been recently accepted in the clinic. In this study, we examined a biological significance of PDT with a chlorin-based photosensitizer, Photodithazine, on cervical cancer model. When human papillomavirus type 16 (HPV16)- transformed mouse TC-1 cells were exposed to varied doses of Photodithazine with light irradiation (6.25 J/cm2), the significant growth inhibition of TC-1 cells was observed at 0.75 μg/mL of Photodithazine. The damaged cells by Photodithazine/PDT were categorized to be early and late apoptosis, as determined by annexin V staining. Photodithazine was primarily localized at lysosome apparatus within TC-1 cells while it was rapidly accumulated and sustained for initial 3 h in tumor tissue of TC-1 tumor bearing mice after IV injection. The tumor growth inhibition by Photodithazine/PDT with light irradiation (300 J/cm2) was examined after injection of various concentration of Photodithazine in tumor mice system. Our results show that Photodithazine/PDT might have significant advantages in the selective killing of tumor lesions in HPV 16 E6/E7 associated cervical cancer model, both in vitro and in vivo.