en Radiation Biology Radiation Biology تحقيق بديع Original Research <span style="font-weight: bold">Background:</span> Glioblastoma is the most common and most malignant cancer of central nervous system. Targeted radiotherapy is an effective method toward its treatment. Iododeoxyuridine (IUdR) is a halogenated thymidine analogue known to be effective as a radiosensitizer in human cancer therapy. In this study we have evaluated the combination effects of 2-Methoxyestradiol, an inhibitor of hypoxia inducible factor 1α (HIF-1α) and Methoxyaminem, an inhibitor of base excision repair (BER) pathway on radiosensitization of IUdR in glioblastoma spheroid culture. <span style="font-weight: bold">Materials and Methods: </span>The cytotoxic damages of DNA in U87MG cell line were compared using colony formation assay. Experiments were performed in large spheroids with a diameter of approximately 350μm. <span style="font-weight: bold">Results:</span> Evaluation of the effects of IUdR with 2ME2 and MX pretreatment on spheroid cultured cell followed by ionizing irradiation showed more enhancemented (p≤0.001) IUdR induced-radiosensitization. These results introduced a key role for 2ME2 in IUdR related studies. <span style="font-weight: bold">Conclusion: </span>Pretreatment of tumor cells with IUdR, MX and 2ME2 before irradiation enhances tumor radiosensitization and may improve therapeutic index for IUdR and 2ME2. Iran. J. Radiat. Res., 2010 7 (4): 211-216 Hypoxia-inducible factor-1α, IUdR, radiosensitization, spheroid, methoxyamine, 2-methoxyestradiol. 211 216 http://ijrr.com/browse.php?a_code=A-10-1-339&slc_lang=en&sid=1 A. Neshasteh-Riz neshastehriz@yahoo.com 790031947532846001808 790031947532846001808 Yes S. Babaloui 790031947532846001914 790031947532846001914 No S. Khoei 790031947532846001915 790031947532846001915 No