The outcome of 5-ALA-mediated photodynamic treatment in melanoma cells is influenced by vitamin C and heme oxygenase-1.

Photodynamic therapy (PDT) is an important clinical approach for cancer treatment. It involves the administration of a photosensitizer, followed by its activation with light and induction of cell death. The underlying mechanism is an increased production of reactive oxygen species (ROS) leading to oxidative stress, which is followed by cell death.

Light-induced cytotoxicity after aminolevulinic acid treatment is mediated by heme and not by iron.

Photodynamic therapy (PDT) is a promising antitumor treatment strategy. However, effectiveness of PDT is limited due to an initiation of rescue responses in tumor cells, including the induction of heme oxygenase-1 (HO-1). Furthermore, the main sources of free radical production in PDT-induced oxidative stress are not clear.