The Telomerase inhibitor MST-312 additively sensitizes HeLa cells to carbon-ion irradiation

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

It is needed to accumulate the more evidence for combined therapy between heavy ions and chemical agents for overcoming refractory tumors. Here, we investigate a combination effect of carbon-ion irradiation and the telomerase inhibitor MST-312 treatment in human cervical cancer HeLa cells by means of a colony formation assay. 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. MST-312 treatment additively decreased the survival of irradiated cells. 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 in carbon-ion irradiation and from 5.4 Gy to 4.0 Gy in -ray irradiation, respectively. MST-312 pre-treatment may reduce the doses needed for a curative effect in heavy ion radiotherapy.