title: From radioresistance to radiosensitivity: In vitro evolution of L5178Y lymphoma.
abstract: OBJECTIVE
  To discuss the possible reasons for the loss of tumourigenicity and the acquisition of new phenotypic features (among them, sensitivity to X and UVC radiations) as a result of in vitro cultivation of L5178Y lymphoma cells.
  
  
  RESULTS
  Ten years ago the phenotypic differences between LY-R (original L5178Y maintained in vivo and examined in vitro) and LY-S lines were reviewed in detail by the author. The loss of tumourigenicity of LY-R cells upon in vitro cultivation accompanying the acquirement of the LY-S phenotype had been described earlier by Beer et al. (1983). In spite of their common origin, the sublines were shown to differ in their relative sensitivity to a number of DNA damaging agents and in numerous other features. Here, selected differences between LY-R and LY-S lines are briefly reviewed. It is proposed that Wallace's concept (2010a) that mitochondria are the interface between environmental conditions and the genome may explain the LY-R-LY-S conversion under prolonged in vitro cultivation.
  
  
  CONCLUSIONS
  The differences between the LY lines were probably of epigenetic rather than genetic character. The properties of LY-R cells changed as a result of exposure to an oxic in vitro milieu. The changes could be preconditioned by heteroplasmy and the selection of cells endowed with mitochondria best fitted to a high oxygen-low carbon dioxide environment.
authors: Centre for Radiobiology and Biological Dosimetry, Institute of Nuclear Chemistry and Technology , Warsaw , Poland.
authors: Irena
authors: I
authors: Szumiel
mesh_terms: D000818:Animals; D005075:Biological Evolution; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004249:DNA Damage; D044127:Epigenesis, Genetic / Q000528:radiation effects; D042822:Genomic Instability / Q000528:radiation effects; D007940:Leukemia L5178 / Q000235:genetics / Q000473:pathology / Q000532:radiotherapy*; D051379:Mice; D008928:Mitochondria / Q000235:genetics / Q000528:radiation effects; D018384:Oxidative Stress / Q000528:radiation effects; D010641:Phenotype; D011836:Radiation Tolerance / Q000235:genetics; D059016:Tumor Microenvironment / Q000235:genetics / Q000528:radiation effects
keywords: L5178Y lymphoma; LY sublines; epigenetics; genomic instability; in vitro evolution; mitochondrion; oxidative stress; radiosensitivity