Combined treatment of HeLa cells with carbon-ion irradiation and the telomerase inhibitor MST-312

Yokota, Yuichiro; Funayama, Tomoo; Hamada, Nobuyuki*; Sakashita, Tetsuya; Suzuki, Michiyo; Kobayashi, Yasuhiko

Here, we investigate a combination effect of carbon-ion irradiation and the telomerase inhibitor MST-312 treatment. Human cervical cancer HeLa cells were cultured for 24 h with or without 1 M MST-312, and then, irradiated with carbon ions (LET=110 keV/m) and -rays. After irradiation, cells were reseeded in fresh medium without MST-312 and colonies were counted as described above. The survival of the irradiated cells additively decreased in combination with MST-312 treatment. Irradiation and MST-312 treatment might inactivate the clonogenic potential of tumor cells through independent mechanisms. The doses needed to reduce the survival of irradiated cells to 10% were decreased by MST-312 treatment from 1.2 Gy to 0.5 Gy (carbon-ion irradiation) and from 5.4 Gy to 4.0 Gy (-ray irradiation), respectively. MST-312 pre-treatment may reduce the dose needed for a curative effect in heavy-particle radiotherapy.