Evaluation of the efficacyof aminolevulinic acid-dependent photodynamic therapy on melanoma cancer cells treated with tocopherol succinate (in-vitro)

Photodynamic therapy (PDT) using 5-aminolevulinic acid (ALA) to produce an intracellular photo-sensitizer, a protoporphyrin molecule IX (PPIX) which absorbs light and targets cells, is a promising cancer treatment. Unfortunately, treatment failures are still a common occurrence when ALA is used. In this study, in order to enhance the efficacy of ALA-dependent photodynamic therapy, the effects of photodynamic therapy on melanoma cancer cells were studied after treating them with tocopherol succinate.

In this experimental study melanoma cells were cultured in RPMI 1640 medium for 24 h. then, cells were treated with tocopherol succinate (6μm/ml). After 48 and 72 hours, the mediums were replaced by serum-free medium in the darkness, with ALA, 0.1mg/ml and then cells incubated for 4h. After that, cells were irradiated by using Nd: YAG laser (532 nm). After 24h, cell survival was measured by the MTT assay.

Twenty-four hours after PDT, among compared groups, pretreated cells with tocopherol succinate showed significant lower cell viability than control group.

Induction of differentiation by using tocopherol succinate augmented intracellular PPIX accumulation in cells treated with ALA. Therefore phototoxic cell death after exposure to 532nm light enhances significantly in tocopherol succinate-pretreated cells. This study suggests that tocopherol succinate may act as a biological enhancer of ALA based photodynamic therapy.