Hydrogen Peroxide Enhances Radiation-induced Apoptosis and Inhibition of Melanoma Cell Proliferation

The efficacy of radiation therapy (RT) for melanoma is limited in part by its radioresistance. Here, we examined the radiosensitizing effect of hydrogen peroxide (H 2 O 2 ) on a radioresistant melanoma cell line, HTB-65. We found that H 2 O 2 synergized with RT to inhibit melanoma cell proliferation and promote apoptosis. The antiproliferative effect of H 2 O 2 /RT correlated with increased expression of p15 and reduced expression of cyclin D, cyclin E, cyclin- dependent kinase (CDK)2 and CDK4. The pro-apoptotic effect of H 2 O 2 /RT correlated with reduced expression of the B-cell CLL/lymphoma (BCL)2. These data highlight the potential of H 2 O 2 as a radiation sensitizer for melanoma treatment and show that this warrants further study.