MDA-MB-231 cell line is sensitized to ionizing radiation using an antimanic drug

Radiotherapy is used in treating a majority of patients having breast cancer. Recurrence of breast cancer is life-threatening and tried to be hindered by prescribing radiosensitizers together with radiotherapy. Lithium has been used as an antimanic drug for more than six decades. The effect of lithium chloride (LiCl) on decreasing brain, esophagus and breast cancer cell proliferation has been reported previously. However, its effect on radiotherapy efficiency has been studied recently. LiCl decreased radioresistance in T47D breast cancer cell line. We studied the effect of LiCl on radiosensitivity of MDA-MB-231 breast cancer cell line to determine whether the previously observed effect of LiCl is extendable. MDA-MB-231 is an invasive breast cancer cell line with negative expression for estrogen and progesterone receptors and represents an advanced stage of breast cancer. Suitable concentration and treatment time was determined by MTT assay. Our results indicated that treatment of MDA-MB-231 cells with a non-lethal concentration of LiCl for 24 hours that caused little decrease in cell proliferation was suitable for the radiotherapy experiments. Control and LiCl-treated cells were radiated with 4 Gy dose of X-ray with 300 Mn/min dose rate and 6 Mv energy. Growth curves of mentioned groups indicated that treatment with LiCl significantly decreased cell proliferation and increased radiosensitivity in MDA-MB-231 breast cancer cell line.