Radiation enhancing effects with the combination of sanazole and irinotecan in hypoxic HeLa human cervical cancer cell line.

PURPOSE This study was conducted to determine the synergistic radiation sensitizing effects of the combination of sanazole and irinotecan in hypoxic cervical cancer HeLa human tumor cell line. METHODS The 3-(4,5 dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay was used to evaluate the number of surviving cells. Cell cycle was determined by flow cytometry. Surviving cell fractions were determined by the standard in vitro colony formation assay. RESULTS The MTT assay showed that the presence of irinotecan with or without sanazole reduced significantly the cells' viability. Flow cytometry demonstrated that the combination of sanazole and irinotecan led to more HeLa cells blocked in G(2) phase. Cell colony formation assay indicated that the radiosensitivity of hypoxic HeLa cells was enhanced by sanazole and/or irinotecan. CONCLUSION This study showed that the radiation enhancing effects produced by the combination sanazole and irinotecan was significant in hypoxic HeLa cells, which were arrested in the G(2) phase of the cell cycle. This study may provide a new combination modality of radiosensitizers in the radiotherapy of cervical cancer.