Charged Particle Irradiation Effects on Human Chondrosarcoma Cells
Résumé
Chondrosarcoma is well known as a radioresistant tumor. The treatment with charged particle (hadron therapy) has shown better specicity and lower toxicity for the surrounding normal tissue when compared to conventional photon therapy. The present study focuses on evaluating cellular eects of proton irradiation on directly exposed chondrosarcoma cells and bystander normal cells. Chondrosarcoma tumor cells (SW1353 and L835) were directly exposed to a low energy ( ~20 MeV) proton beam line at doses ranging from 0.1 to 4Gy. To study the bystander phenomena we used a medium transfer protocol from the tumor cells irradiated with 0-2Gy to normal cells (T/C-28a2 chondrocyte and EA.hy926 endothelial cell lines). Cell survival, cell death and DNA damage were quantied in directly irradiated chondrosarcoma cells and in bystander chondrocytes and endothelial cells. Proton irradiation induces a dose dependent direct eect in chondrosarcoma cells as augmented number of micronuclei at 24 h after exposure, a reduction of the long-term cellular survival, an elevation in caspase activity at 24h and a decreased metabolic activity after 5 days. In bystander chondrocyte cells, SW1353 cell line induced an increase in micronuclei and a decrease in long term survival at 0.1 Gy, while L835 cells showed an increase in micronuclei number for all doses. In contrast, chondrosarcoma L835 cells induce both an elevation of micronuclei number and a decrease in long-term survival at the dose of 0.5 Gy in endothelial cells, while SW1353 chondrosarcoma cells induce both an increase in micronuclei number and a decrease in survival at 2Gy. The outcomes showed that proton irradiated chondrosarcoma cells release stress factors inducing a wide bystander response in the non-irradiated chondrocyte/endothelial cells.