Photodynamic therapeutic role of indocyanine green in tumor-associated inflammation in skin cancer.

Background: Indocyanine green (ICG) is a promising water-soluble photosensitizer for photodynamic therapy (PDT) of tumors. It was reported to have promising phototoxic effect on different cell lines. This study aimed to evaluate the efficacy of ICG as an efficient PS agent for skin cancer induced in mice.

Methods: Skin squamous cell carcinoma was induced in female CD-1 mice by 7,12-dimethylbenzanthracene and 12-O-tetradecanoyl-phorbol-13-acetate followed by an ICG/PDT treatment. The laser irradiation for PDT was adjusted to cover the whole body of the mice to make sure that the treatment protocol will be delivered to multiple tumors.

Results: The treatment of skin cancer by ICG/PDT using intravenously injected ICG initiated tumor cell death and significantly decreased cell proliferation as indicated by the reduction in proliferating cell nuclear antigen positivity. A significant reduction in the inflammatory mediators; tumor necrosis factor-α, nitric oxide and 5-lipoxygenase was reported, however the level of cyclooxygenase-2 (COX-2) was significantly elevated after ICG/PDT treatment.

Conclusion: The proposed ICG/PDT treatment modality showed a significant anti-tumor and anti-inflammatory activity against skin cancer accompanied with COX-2 elevation.