H. Tatebe

Effect of oxygen pressure during incubation with a 10B-carrier on 10B uptake capacity of cultured p53 wild-type and mutated tumor cells: dependency on p53 status of tumor cells and types of 10B-carriers

Abstract Purpose To evaluate the effect of oxygen pressure during incubation with a 10B-carrier on 10B uptake capacity of cultured p53 wild-type and mutated tumor cells. Materials and methods Cultured human head and neck squamous cell carcinoma cell line transfected with mutant TP53 (SAS/mp53), or with a neo vector as a control (SAS/neo) was incubated with L-para-boronophenylalanine-10B (BPA) or sodium mercaptoundecahydrododecaborate-10B (BSH) as a 10B-carrier at the 10B concentration of 60 ppm for 24 h under aerobic (20.7% of oxygen) or hypoxic (0.28% of oxygen) conditions. Immediately after incubation, cultured tumor cells received reactor thermal neutron beams, and a cell survival assay was performed. 10B concentration of cultured SAS/neo or SAS/mp53 cells incubated under aerobic or hypoxic conditions was determined with a thermal neutron guide tube. Results Hypoxic incubation significantly decreased 10B concentration of cultured cells with a clearer tendency observed following BPA than BSH treatment in both SAS/neo and SAS/mp53 cells. Following neutron beam irradiation, SAS/mp53 cells showed significantly higher relative biological effectiveness values than SAS/neo cells because of the significantly lower radiosensitivity of SAS/mp53 to γ-rays than SAS/neo cells. Conclusion Oxygen pressure during incubation with a 10B-carrier had a critical impact on 10B uptake of cultured tumor cells.