Melanoma, known as the most aggressive form of skin cancer, poses a significant threat due to its high potential for metastasis. The primary risk factor for developing this disease is prolonged exposure to ultraviolet rays, which induces oxidative stress and inflammation in skin cells through photo-oxidation reactions.
Interestingly, both ultraviolet and visible light have the ability to activate photosensitizers naturally present in tissues. This activation process converts light energy into chemicals, generating reactive oxygen species that can damage biomolecules within the cells. While these reactions can be detrimental, they can also be harnessed for therapeutic purposes such as photodynamic therapy, which targets tumor cells or pathogens.
Researchers at the Center for Research on Redox Processes in Biomedicine (Redoxoma) at the University of São Paulo have been exploring the potential of oxidizing compounds in combination with photodynamic therapy as a novel strategy for combating melanoma. In a recent study led by Professor Sayuri Miyamoto, the team discovered that endoperoxides derived from the oxidation of specific lipids induce the death of melanoma cells. These findings were published in the journal Photochemistry and Photobiology.
The focus of the study was to optimize photodynamic therapy, a less invasive treatment option compared to conventional methods like surgery. By understanding the effects of oxidizing compounds on cell membranes, the researchers aimed to enhance the efficacy of this therapy. The study also delved into the mechanisms behind light-induced oxidative damage to cell membranes, analyzing the impact of different oxidants on sterols like ergosterol and 7-dehydrocholesterol (7-DHC) commonly found in cell membranes.
A key revelation from the research was the varying effects of oxidative damage on cell membrane permeability depending on the type of oxidation. The study classified photo-oxidation reactions into Type I and Type II mechanisms, each producing different reactive species. Interestingly, the researchers found that cholesterol acted as an antioxidant in Type II oxidations, protecting cell membranes from damage induced by singlet oxygen.
Moreover, the study highlighted the formation of stable endoperoxides from 7-DHC and ergosterol during oxidation processes. These endoperoxides demonstrated potent effects in eliminating melanoma cells when used in conjunction with photodynamic therapy. Moving forward, the researchers plan to further investigate the impact of different concentrations of endoperoxides and radiation doses on their efficacy against melanoma cells.
Overall, this study sheds light on the potential of oxidizing compounds in enhancing the effectiveness of photodynamic therapy for melanoma treatment. By unraveling the mechanisms of oxidative damage to cell membranes and exploring the properties of specific sterols and their derivatives, the researchers aim to develop innovative strategies for combating this aggressive form of skin cancer.
