Ellagic Acid: A potent Radio-sensitizer in Cancer Radiotherapy

The cytotoxic effect of radiotherapy of cancer is limited due to commonly observed radio-resistance in the clinic. It is, therefore, necessary to develop new strategies to enhance the radiosensitivity of tumor cells by combining therapeutic drugs with optimized radiation doses to improve the treatment outcome. Over the years, research has gained momentum in studying various herbal drugs that have the potential to sensitize tumor cells to ionizing radiation. Herbal drugs possess the property of non-toxic doses to higher concentrations and thereby minimize the undesirable side effects. Our lab recently reported the combined effects of radiation and ellagic acid (EA) in generation of increasing ROS as a function of radiation dose in HeLa thereby exhibiting the radiosensitizing effect. This article reviews the mechanism of action of EA involving ROS, cell cycle arrest, apoptosis and activation of signaling molecular cascade as observed in radiosensitization of some tumor cell lines. These studies suggest its potential usefulness in clinics for improving cancer radiotherapy which works by the mechanism of increasing the oxidative stress through generation of ROS in cancer cells.