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Aim:To investigate the effect of the Tob1 gene,a member of the TransducingMolecule of ErbB2/B-cell Translocation Ggene (TOB/BTG) family,by usingthe adenovirus-mediated expression of Tob 1 on radiosensitivity in a human breastcancer cell line MDA-MB-231.Methods:Cell survival was determined byclonogenic assay.Apoptosis was evaluated by DNA fragmentation gel electro-phoresis and terminal deoxynucleotidyl transferase-mediated nick end labelingassay.Protein expression was analyzed by Western blot assay and DNA repairwas measured by a host cell reactivation assay.Results:We demonstrated thatpre-irradiation treatment with Ad5-Tob 1 significantly increased radiosensitivity,accompanying the increased induction of apoptosis and the repression of DNAdamage repair.Furthermore,Ad5-Tob 1-mediated radiosensitivity correlates withthe upregulation of the pro-apoptotic protein Bax and the downregulation ofseveral DNA double strand break repair proteins,including DNA-dependent pro-tein kinases,Ku70 and Ku80,and X-ray-sensitive complementation group 4.Conclusion:Tob1,as a new radiosensitizer,is a new target in the radiotherapyof breast cancer via increasing apoptosis and suppressing DNA repair.
Aim: To investigate the effect of the Tob1 gene, a member of the Transducing Molecule of ErbB2 / B-cell Translocation Ggene (TOB / BTG) family, by using the adenovirus-mediated expression of Tob 1 on radiosensitivity in a human breast cancer cell line MDA- MB-231. Methods: Cell survival was determined byclonogenic assay. Apoptosis was evaluated by DNA fragmentation gel electro-phoresis and terminal deoxynucleotidyl transferase-mediated nick end labeling assay. Protein expression was analyzed by Western blot assay and DNA repair was measured by a host cell reactivation assay. Results: We demonstrated thatpre-irradiation treatment with Ad5-Tob1 significantly increased radiosensitivity, accompanying the increased induction of apoptosis and the repression of DNAdamage repair. Fultrthermore, Ad5-Tob 1-mediated radiosensitivity correlates with the upregulation of the pro- apoptotic protein Bax and the downregulation of serum DNA double strand break repair proteins, including DNA-dependent pro-tein kinases, Ku70 and K u80, and X-ray-sensitive complementation group 4. Conlusion: Tob1, as a new radiosensitizer, is a new target in the radiotherapy of breast cancer via increasing apoptosis and suppressing DNA repair.