title: Low-dose hyper-radiosensitivity is not a common effect in normal asynchronous and G2-phase fibroblasts of cancer patients.
abstract: OBJECTIVE
  In our previous study, using the micronucleus assay, a low-dose hyper-radiosensitivity (HRS)-like phenomenon was observed for normal fibroblasts of 2 of the 40 cancer patients investigated. In this article we report, for the first time, the survival response of primary fibroblasts from 25 of these patients to low-dose irradiation and answer the question regarding the effect of G2-phase enrichment on HRS elicitation.
  
  
  METHODS
  The clonogenic survival of asynchronous as well as G2-phase enriched fibroblast populations was measured. Separation of G2-phase cells and precise cell counting was performed using a fluorescence-activated cell sorter. Sorted and plated cells were irradiated with single doses (0.1-4 Gy) of 6-MV x-rays. For each patient, at least 4 independent experiments were performed, and the induced-repair model was fitted over the whole data set to confirm the presence of HRS effect.
  
  
  RESULTS
  The HRS response was demonstrated for the asynchronous and G2-phase enriched cell populations of 4 patients. For the rest of patients, HRS was not defined in either of the 2 fibroblast populations. Thus, G2-phase enrichment had no effect on HRS elicitation.
  
  
  CONCLUSIONS
  The fact that low-dose hyper-radiosensitivity is not a common effect in normal human fibroblasts implies that HRS may be of little consequence in late-responding connective tissues with regard to radiation fibrosis.
authors.affiliation: Department of Applied Radiobiology, Centre of Oncology, Maria-Skłodowska-Curie Memorial Institute Kraków, Kraków, Poland. Electronic address: z5slonin@cyfronet.pl.
authors.forename: Dorota
authors.initials: D
authors.lastname: Słonina
authors.affiliation: Department of Applied Radiobiology, Centre of Oncology, Maria-Skłodowska-Curie Memorial Institute Kraków, Kraków, Poland.
authors.forename: Beata
authors.initials: B
authors.lastname: Biesaga
authors.affiliation: Department of Applied Radiobiology, Centre of Oncology, Maria-Skłodowska-Curie Memorial Institute Kraków, Kraków, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Janecka
authors.affiliation: Department of Medical Physics, Centre of Oncology, Maria-Skłodowska-Curie Memorial Institute Kraków, Kraków, Poland.
authors.forename: Damian
authors.initials: D
authors.lastname: Kabat
authors.affiliation: Jagiellonian Centre for Experimental Therapeutics (JCET), Jagiellonian University, Kraków, Poland.
authors.forename: Karolina
authors.initials: K
authors.lastname: Bukowska-Strakova
authors.affiliation: Department of Applied Radiobiology, Centre of Oncology, Maria-Skłodowska-Curie Memorial Institute Kraków, Kraków, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Gasińska
mesh_terms: D002469:Cell Separation / Q000379:methods; D002470:Cell Survival / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000528:radiation effects*; D005434:Flow Cytometry / Q000379:methods; D016195:G2 Phase / Q000502:physiology; D006801:Humans; D011836:Radiation Tolerance; D014410:Tumor Stem Cell Assay / Q000379:methods; D002583:Uterine Cervical Neoplasms / Q000473:pathology / Q000532:radiotherapy