Effects of curcumin based PDT on the viability and the organization of actin in melanotic (A375) and amelanotic melanoma (C32) – in vitro studies

Curcumin is a turmeric, antioxidative compound, well-known of its anti-cancer properties. Nowadays more and more effort is made in the field of enhancing the efficiency of the anticancer therapies. Combining the photoactive properties of curcumin with the superficial localization of melanoma and photodynamic therapy (PDT) seems to be a promising treatment method. The research focused on the evaluation of the curcumin effectiveness as an anticancer therapeutic agent in the in vitro treatment of melanotic (A375) and amelanotic (C32) melanoma cell lines. Keratinocytes (HaCat) and fibroblasts (HGF) were used to assess the impact of the therapy on the skin tissue. The aim of the study was to investigate the cell death after exposure to light irradiation after preincubation with curcumin. Additionaly the authors analized the interactions between curcumin and the actin cytoskeleton. The cytotoxic effect initiated by curcumin and increased by irradiation confirm the usefulness of the flavonoid in the PDT approach. Depending on curcumin concentration and incubation time, melanoma cells survival rate ranged from: 93.68 % (C32 cell line, 10 μM, 24 h) and 83.47 % (A375 cell line, 10 μM, 24 h) to 8.98 % (C32 cell line, 50 μM, 48 h) and 12.42 % (A375 cell line, 50 μM, 48 h). Moreover, photodynamic therapy with curcumin increased the number of apoptotic and necrotic cells in comparison to incubation with curcumin without irradiation. The study demonstrated that PDT induced caspase-3 overexpression and DNA cleavage in the studied cell lines. The cells revealed decreased proliferation after the therapy due to the actin cytoskeleton rearrangement. Although effective, the therapy remains not selective towards melanoma cells.