P 014: Study of Bystander Effects in Chondrosarcoma Cells Irradiated In Vitro with X-Rays and Carbon Ions
Résumé
Hadrontherapy with carbon ions seems to be a good alternative for the treatment of cancer resistant to conventional radiotherapy. Chondrosarcoma is a candidate for hadrontherapy because this cancer is radio and chemo resistant, and can be un-operable, when located in the skull base. However, it is necessary to evaluate the secondary effects of this irradiation type, especially the interaction between irradiated and non-irradiated cells. Among these effects, the radiation-induced bystander effect involves stress signals emitted by irradiated cells adjacent or very close to non-irradiated cells; bystander molecules can induce a biological response with damages usually observed with irradiated cells. To study this phenomenon, we used a protocol of medium transfer. Cells are irradiated with X-rays or carbon ions and then the bystander supernatant, containing the signals emitted by irradiated cells, is transferred on non-irradiated cells. Chondrosarcoma cells and chondrocytes were analyzed as emitting and/or receptor cells of bystander signals. We use different technical strategies, such as clonogenic assay, to study the survival cells fraction after treatment; multiplex Elisa analysis of conditioned medium for the identification of bystander factors and flow cytometry for cell cycle analysis of irradiated and bystander cells. Our results showed a significant reduction of chondrocyte survival after transfer of conditioned medium from chondrosarcoma cells irradiated with low doses of X-rays and C-ions. By diluting this medium, the phenomenon decreased proportionally, confirming the presence of bystander factors. Some of these factors were partially observed using multiplex analysis of cell cytokines.
