title: Modulation of clonogenicity, growth, and radiosensitivity of three human epidermoid tumor cell lines by a fibroblastic environment.
abstract: OBJECTIVE
  To develop a model vitro system to examine the influence of fibroblasts on the growth and survival of human tumor cells after exposure to ionizing radiation.
  
  
  METHODS
  The cell system of three epidermoid carcinoma cell lines derived from head and neck tumors having differing growth potentials and intrinsic radiosensitivities, as well as a low passage skin fibroblast strain from a normal human donor. The tumor cells were seeded for five days prior to exposure to radiation: (a) in the presence of different numbers of fibroblasts, (b) in conditioned medium from stationary fibroblast cultures, and (c) on an extracted fibroblastic matrix.
  
  
  RESULTS
  When grown with fibroblasts, all three tumor cell lines showed increased clonogenicity and increased radioresistance. The radioprotective effect was maximal at a density of approximately 10(5) fibroblasts/100 mm Petri dish, and was greatest in the intrinsically radiosensitive tumor cell line. On the other hand, the effects of incubation with conditioned medium or on a fibroblastic matrix varied among the tumor cell lines. Thus, the protective effect afforded by coculture with fibroblasts must involve several cellular factors related to the fibroblast itself.
  
  
  CONCLUSIONS
  These observations emphasize the importance of cultural conditions on the apparent radiosensitivity of human tumor cell lines, and suggest that the fibroblastic connective tissue enveloping the malignant cells should be considered when the aim is to establish a radiopredictive assay from surgical tumor fragments.
authors.affiliation: Department of Cancer Biology, Harvard School of Public Health, Boston, MA, USA.
authors.forename: B
authors.initials: B
authors.lastname: Gery
authors.forename: J
authors.initials: J
authors.lastname: Coppey
authors.forename: J B
authors.initials: JB
authors.lastname: Little
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000473:pathology* / Q000532:radiotherapy; D002450:Cell Communication; D002452:Cell Count; D002455:Cell Division; D002470:Cell Survival / Q000528:radiation effects; D018920:Coculture Techniques; D017077:Culture Media, Conditioned / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology*; D006801:Humans; D011836:Radiation Tolerance; D014407:Tumor Cells, Cultured / Q000473:pathology / Q000528:radiation effects; D014410:Tumor Stem Cell Assay
chemical_list: D017077:Culture Media, Conditioned