Anti-tumor effects of liposome-encapsulated titanium dioxide in nude mice

Anatase particles of titanium dioxide (TiO2) absorb ultraviolet ( UV) light which is shorter than 415 nm. Photoexcited TiO2, a strong oxidizer, is expected to inhibit malignant cell growth. Liposomes accelerate endophagocytosis to the cytoplasm of encapsulated materials. In this study, we examined anti-tumor effects of TiO2 and liposome- encapsulated TiO2 (LT) with UVA irradiation by an air pouch cancer model using NBT-II bladder cancer cells, which simulates bladder cancer. Injection of TiO2 or LT into the air pouch was followed by UVA irradiation via the opened pouch. Tumors of TiO2 + UVA and LT + UVA groups showed more pronounced necrotic areas, apoptotic indices, nitrotyrosine formation, tumor growth inhibition and increased survival compared with control groups. Especially the LT + UVA group showed more remarkable anti- tumoral effects than the TiO2 + UVA group, which was associated with higher TiO2 incorporation. These findings suggest that LT might be more effective than noncoated TiO2 in the treatment of bladder cancer. Copyright (c) 2007 S. Karger AG, Basel.