Bystander effectors of chondrosarcoma cells irradiated at different LET impair proliferation of chondrocytes

While the dose-response relationship of radiation-induced bystander effect (RIBE) is controversial at low and high linear energy transfer (LET), mechanisms and effectors of cell-to-cell communication stay unclear and highly dependent of cell type. In the present study, we investigated the capacity of chondrocytes in responding to bystander factors released by chondrosarcoma cells irradiated at different doses (0.05 to 8 Gy) with X-rays and C-ions. Following a medium transfer protocol, cell survival, proliferation and DNA damages were quantified in bystander chondrocytes. The bystander factors secreted by chondrosarcoma cells were characterized. A significant and major RIBE response was observed in chondrocyte cells (T/C-28a2) receiving conditioned medium from chondrosarcoma cells (SW1353) irradiated with 0.1 Gy of X-rays and 0.05 Gy of C-ions, resulting in cell survivals of 36% and 62%, respectively. Micronuclei induction in bystander cells was observed from the same low doses. The cell survival results obtained by clonogenic assays were confirmed using impedancemetry. The bystander activity was vanished after a heat treatment or a dilution of the conditioned media. The cytokines which are well known as bystander factors, TNF-alpha and IL-6, were increased as a function of doses and LET according to an ELISA multiplex analysis. Together, the results demonstrate that irradiated chondrosarcoma cells can communicate stress factors to non-irradiated chondrocytes, inducing a wide and specific bystander response related to both doses and LET

Bystander effectors of chondrosarcoma cells irradiated at different LET impair proliferation of chondrocytes

International audienceX-rays / Carbon Ion Tumor (Chondrosarcoma) Non irradiated area arrounding tumor Non irradiated area arrounding healthy tissue Direct effect of irradiation Bystander effect Bystander effectors of chondrosarcoma cells irradiated at different LET impair proliferation of chondrocyte

Bystander Effects of human chondrosarcoma cells irradiated with accelerated ions

International audienceFor the treatment of cancer resistant to conventional radiotherapy, hadrontherapy with carbon ions seems to be a good alternative. Hadrontherapy uses accelerated ions; this technique is interesting when the tumor is deep and isolated or located close to sensible organs. Indeed, the dose deposit is maximal within the tumor volume (Bragg pick), and minimal before and after the tumor, preserving the surrounding healthy tissues. Chondrosarcoma is a good 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 [1,2]. 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 to study the survival cells fraction after treatment, the DNA damages and to identify of bystander factors. 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. Taken together, these results showed the capacity of chondrosarcoma cells to secrete bystander signals, particularly at low irradiation dose, and the capacity of chondrocyte cells to receive these signals. Even if in vivo experiments are still required, these results open the discussion with the medical staff for protocol adaptations during radiotherapy, in order to limit the damaging impact of bystander effect within the healthy tissues

Bystander Effects of human chondrosarcoma cells irradiated with accelerated ions

International audienceFor the treatment of cancer resistant to conventional radiotherapy, hadrontherapy with carbon ions seems to be a good alternative. Hadrontherapy uses accelerated ions; this technique is interesting when the tumor is deep and isolated or located close to sensible organs. Indeed, the dose deposit is maximal within the tumor volume (Bragg pick), and minimal before and after the tumor, preserving the surrounding healthy tissues. Chondrosarcoma is a good 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 [1,2]. 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 to study the survival cells fraction after treatment, the DNA damages and to identify of bystander factors. 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. Taken together, these results showed the capacity of chondrosarcoma cells to secrete bystander signals, particularly at low irradiation dose, and the capacity of chondrocyte cells to receive these signals. Even if in vivo experiments are still required, these results open the discussion with the medical staff for protocol adaptations during radiotherapy, in order to limit the damaging impact of bystander effect within the healthy tissues

Pilot screening of potential matrikines resulting from collagen breakages through ionizing radiation

International audienceLittle is known regarding radiation-induced matrikines and the possible degradation of extracellular matrix following therapeutic irradiation. The goal of this study was to determine if irradiation can cut collagen proteins at specific sites, inducing potentially biologically active peptides against cartilage cells. Chondrocytes cultured as 3D models were evaluated for extracellular matrix production. Bystander molecules were analyzed in vitro in the conditioned medium of X-irradiated chondrocytes. Preferential breakage sites were analyzed in collagen polypeptide by mass spectrometry and resulting peptides were tested against chondrocytes. 3D models of chondrocytes displayed a light extracellular matrix able to maintain the structure. Irradiated and bystander chondrocytes showed a surprising radiation sensitivity at low doses, characteristic of the presence of bystander factors, particularly following 0.1 Gy. The glycine-proline peptidic bond was observed as a preferential cleavage site and a possible weakness of the collagen polypeptide after irradiation. From the 46 collagen peptides analyzed against chondrocytes culture, 20 peptides induced a reduction of viability and 5 peptides induced an increase of viability at the highest concentration between 0.1 and 1 µg/ml. We conclude that irradiation promoted a site-specific degradation of collagen. The potentially resulting peptides induce negative or positive regulations of chondrocyte growth. Taken together, these results suggest that ionizing radiation causes a degradation of cartilage proteins, leading to a functional unbalance of cartilage homeostasis after exposure, contributing to cartilage dysfunction

Bystander effectors of chondrosarcoma cells irradiated at different LET impair proliferation of chondrocytes

While the dose-response relationship of radiation-induced bystander effect (RIBE) is controversial at low and high linear energytransfer (LET), mechanisms and effectors of cell-to-cell communication stay unclear and highly dependent of cell type. In thepresent study, we investigated the capacity of chondrocytes in responding to bystander factors released by chondrosarcoma cells irradiated at different doses (0.05 to 8 Gy) with X-rays and C-ions. Following a medium transfer protocol, cell survival,proliferation and DNA damages were quantified in bystander chondrocytes. The bystander factors secreted by chondrosarcomacells were characterized. A significant and major RIBE response was observed in chondrocyte cells (T/C-28a2) receiving conditioned medium from chondrosarcoma cells (SW1353) irradiated with 0.1 Gy of X-rays and 0.05 Gy of C-ions, resulting in cell survivals of 36% and 62%, respectively. Micronuclei induction in bystander cells was observed from the same low doses. The cell survival results obtained by clonogenic assays were confirmed using impedancemetry. The bystander activity was vanished after a heat treatment or a dilution of the conditioned media. The cytokines which are well known as bystander factors,TNF-α and IL-6, were increased as a function of doses and LET according to an ELISA multiplex analysis. Together, the results demonstrate that irradiated chondrosarcoma cells can communicate stress factors to non-irradiated chondrocytes, inducing a wide and specific bystander response related to both doses and LET