Initiation of Apoptosis in Cells Exposed to Medium from the Progeny of Irradiated Cells: A Possible Mechanism for Bystander-Induced Genomic Instability?

Genomic instability and bystander effects have recently been linked experimentally both in vivo and in vitro. The aim of the present study was to determine if medium from irradiated cells several passages distant from the original exposure could initiate apoptosis in unirradiated cells. Human keratinocytes (from the HPV-G cell line) were irradiated with 0.5 Gy or 5 Gy gamma rays. Medium was harvested at each passage up to the 7th passage …