title: Alterations in growth phenotype and radiosensitivity after fractionated irradiation of breast carcinoma cells from a single patient.
abstract: OBJECTIVE
  To investigate growth regulation and radiosensitivity in surviving clonogens after fractionated irradiation.
  
  
  METHODS
  Four breast carcinoma cell lines isolated from the primary tumor (21NT, 21PT) and metastases (21MT-1, 21MT-2) of a single patient were exposed to cumulative radiation doses of 30 Gy yielding cell lines designated-IR with respect to their parent. The irradiated lines were then compared to their parent for serum-and growth factor-requirements under defined media conditions, ability to proliferate in soft agar, concentration of TGF-alpha in conditioned medium, and radiosensitivity.
  
  
  RESULTS
  The irradiated lines showed no change in proliferative doubling times under serum- and growth factor-supplemented media conditions. A single line, 21MT-1-IR, acquired a limited ability to proliferate in serum-and growth factor-deplete medium with a day 2-4 doubling time of 44.5 hr. Three lines, 21MT-1-IR, 21MT-2-IR, and 21NT-IR, formed colonies in soft agar in contrast to none of the unirradiated parent lines. There were significant 6-8 fold increases in conditioned media TGF-alpha concentrations for 21MT-2-IR and 21NT-IR cells. The 21MT-1-IR and 21NT-IR cells were significantly less radiosensitive than their respective parent lines. This decrease in radiosensitivity appeared to be at least partially mediated by a released factor as the radiosensitivity of 21MT-1 cells was significantly decreased by pre-incubation with conditioned medium from 21MT-1-IR cells.
  
  
  CONCLUSIONS
  Radiation-induced changes in growth phenotype vary with respect to clonal origin of the cell line and may influence the radiosensitivity of surviving clonogens after fractionated treatment.
authors: Department of Radiation Oncology, Tufts University School of Medicine, New England Medical Center, Boston, MA 02111.
authors: D E
authors: DE
authors: Wazer
authors: M
authors: M
authors: Joyce
authors: L
authors: L
authors: Jung
authors: V
authors: V
authors: Band
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology*; D002455:Cell Division / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D010641:Phenotype; D011836:Radiation Tolerance / Q000502:physiology*; D016211:Transforming Growth Factor alpha / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000528:radiation effects*
chemical_list: D016211:Transforming Growth Factor alpha