title: Bystander effects induced by medium from irradiated cells: similar transcriptome responses in irradiated and bystander K562 cells.
abstract: OBJECTIVE
  Cells exposed to ionizing radiation release factors that induce deoxyribonucleic acid damage, chromosomal instability, apoptosis, and changes in the proliferation rate of neighboring unexposed cells, phenomena known as bystander effects. This work analyzes and compares changes in global transcript levels induced by direct irradiation and by bystander effects in K562 (human erythroleukemia) cells.
  
  
  METHODS
  Cells were X-irradiated with 4 Gy or transferred into culture medium collected from cells 1 h after irradiation (irradiation-conditioned medium). Global transcript profiles were assessed after 36 h of growth by use of Affymetrix microarrays (Affymetrix, Santa Clara, CA) and the kinetics of change of selected transcripts by quantitative reverse transcriptase-polymerase chain reaction.
  
  
  RESULTS
  The level of the majority (72%) of transcripts changed similarly (increase, decrease, or no change) in cells grown in irradiation-conditioned medium or irradiated, whereas only 0.6% showed an opposite response. Transcript level changes in bystander and irradiated cells were significantly different from those in untreated cells grown for the same amount of time and were confirmed by quantitative reverse transcriptase-polymerase chain reaction for selected genes. Signaling pathways in which the highest number of transcripts changed in both conditions were found in the following groups: neuroactive ligand-receptor, cytokine-cytokine receptor interaction, Janus Kinase-Signal Transducers and Activators of Transcription (JAK-STAT) and Mitogen-Activated Protein Kinase (MAPK) In control cells more transcripts were downregulated than in irradiated and bystander cells with transcription factors YBX1 and STAT5B, heat shock protein HSPA1A, and ribonucleic acid helicase DDX3X as examples.
  
  
  CONCLUSIONS
  The transcriptomes of cells grown in medium from X-irradiated cells or directly irradiated show very similar changes. Signals released by irradiated cells may cause changes in the transcriptome of neighboring cells that sustain their survival.
authors.affiliation: Department of Experimental and Clinical Radiobiology, Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Gliwice, Poland.
authors.forename: Robert
authors.initials: R
authors.lastname: Herok
authors.forename: Maria
authors.initials: M
authors.lastname: Konopacka
authors.forename: Joanna
authors.initials: J
authors.lastname: Polanska
authors.forename: Andrzej
authors.initials: A
authors.lastname: Swierniak
authors.forename: Jacek
authors.initials: J
authors.lastname: Rogolinski
authors.forename: Roman
authors.initials: R
authors.lastname: Jaksik
authors.forename: Ronald
authors.initials: R
authors.lastname: Hancock
authors.forename: Joanna
authors.initials: J
authors.lastname: Rzeszowska-Wolny
mesh_terms: D024201:Bystander Effect / Q000187:drug effects / Q000528:radiation effects*; D017077:Culture Media, Conditioned / Q000494:pharmacology*; D004249:DNA Damage; D015536:Down-Regulation; D020869:Gene Expression Profiling / Q000379:methods*; D006801:Humans; D020014:K562 Cells / Q000378:metabolism / Q000528:radiation effects*; D011829:Radiation Dosage; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects*; D013997:Time Factors; D015854:Up-Regulation
chemical_list: D017077:Culture Media, Conditioned