Abstract

Co60 photon radiotherapy ís indicated to the breast cancer treatment.  The goal of the present research is to investigate the tumor cell line behavior after gamma irradiation. The human breast carcinoma MDAMB-231 cell line was exposed to a Co60 source at an unique fraction of 10Gy, 25Gy and 50Gy doses at 44cGy/min rate. Cellular viability was evaluated by MTT assay and apoptosis was observed by Propidium Iodide assay at 1h, 24h, 48h and 72h after Co60 irradiation. Cellular viability was evaluated by observing formazan’s crystals formation and by measuring it’s optical density at 595 nm. Apoptotic cells stained by Propidium Iodide were observed by fluorescence microscopy. We observed that high dose of irradiation do not promote significant level of apoptosis in MDAMB-231 cell line when compared to apoptosis induced by 10% methanol. We showed ihat clinical dose used in treatment of human breast carcinoma did not reduce cellular viability in the same cell line. Indeed, viable cells were observed at level of 50Gy suggesting a radioresistent behavior.