The importance of serum serotonin levels in the measurement of radiation-induced bystander cell death in HaCaT cells.
OBJECTIVE
The aim of this study was to investigate the importance of serum serotonin levels in the measurement of bystander cell death. The study was undertaken as part of an intercomparison exercise involving seven European laboratories funded under the European Union Sixth Framework Programme (FP6) Non-Targeted Effects (NOTE) integrated project.


METHODS
Three batches of foetal bovine serum were tested; serum with high and low serotonin content from the intercomparison exercise as well as serum from the home laboratory. Three sets of human keratinocytes (HaCaT cell line) were cultured in DMEM:F12 medium supplemented with serum with high or low serotonin content or serum from the home laboratory and both donor and recipient HaCaT cells were plated. The donor HaCaT cells were irradiated (0.5 Gy) using a cobalt 60 teletherapy unit, the medium was harvested 1 hour post irradiation and transferred to the recipient HaCaT cells. Bystander induced cell death was measured by the clonogenic survival assay and the Alamar blue viability assay.


RESULTS
A significant reduction in cell survival, as measured by the clonogenic assay, and in cell viability, as measured by the Alamar blue assay, was observed in the recipient HaCaT cells treated with medium from irradiated cells compared to the cells treated with medium from unirradiated cells. No significant difference was found between the three batches of serum.


CONCLUSIONS
The data suggest that in our cell system and with our endpoints (clonogenic assay and Alamar blue assay), serum serotonin levels do not play a role in bystander-induced cell death.
DIT Centre for Radiation and Environmental Science, Focas Research Institute, Dublin Institute of Technology, Dublin, Ireland. fiona.lyng@dit.ie
Fiona M
FM
Lyng
Maxime
M
Desplanques
Kishore Kumar
KK
Jella
Amaya
A
Garcia
Brendan
B
McClean
D000818:Animals; D024201:Bystander Effect / Q000187:drug effects* / Q000528:radiation effects*; D002417:Cattle; D018929:Cell Culture Techniques / Q000379:methods*; D016923:Cell Death / Q000187:drug effects* / Q000528:radiation effects*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D003470:Culture Media / Q000737:chemistry*; D006801:Humans; D015603:Keratinocytes / Q000166:cytology; D012701:Serotonin / Q000097:blood / Q000494:pharmacology*
D003470:Culture Media; D012701:Serotonin