Radiation reduces pirarubicin sensitivity in human cervical squamous cell carcinoma cells

To find an effective protocol for chemoradiotherapy with pirarubicin hydrochloride (THP) for advanced cervical cancer patients, effects of irradiation on THP sensitivity were examined using the radiosensitive human cervical squamous cell carcinoma cell line ME180. Concurrent irradiation significantly reduced THP sensitivity, and this was further reduced when cells were treated with THP 8 h after irradiation. However, the THP sensitivity of cells treated with THP 8 h before irradiation was significantly enhanced. Four months after the first irradiation, 4 subclones of ME180 cells that survived repetitive irradiation demonstrated significantly higher THP sensitivity than non-irradiated parent cells. These results indicate that THP injections, more than several hours before irradiation or after completion of radiotherapy, might be better therapies than concurrent chemoradiotherapy with THP for cervical cancer.