Transcription profiling by array of irradated and non-irradiated human K562 human erythroleukemic cells to study the effect of ionizing radiation and the bystander effect

The objective of the experiment was to compare changes in the transcriptome induced by direct X-irradiation of cells and by factors released by irradiated cells into the culture medium (irradiation conditioned medium, ICM), using the K562 human erythroleukemic cell line. Two culture flasks with K562 cells (5 x 105 cells/ml) were irradiated with X-rays at the dose of 4 Gy and in both the culture medium was changed immediately after irradiation, after 1 hour of recovery in fresh medium in standard growth conditions medium containing factors released by irradiated cells was collected from one flask, filtered from cell debris and untreated control K 562 cells were grown in this medium in standard conditions for 36h. The irradiated cells of the second flask were incubated for 36 hours in parallel and RNA was isolated from both irradiated and Irradiation Conditioned Medium-exposed samples. The transcript levels were measured in these RNA samples using Affymetrix HGU 133A microarrays and compared to the levels in RNA from control cells grown for 36h or control cells collected after 1h after change of medium. Experiments were repeated twice.

8