In vitro response of human dermal fibroblasts to X-irradiation: relationship between radiation-induced clonogenic cell death, chromosome aberrations and markers of proliferative senescence or differentiation.
OBJECTIVE
To analyse the relationship between radiation-induced clonogenic cell death, chromosome aberrations and markers of proliferative senescence or differentiation.


METHODS
Plateau-phase human dermal fibroblasts from 18 donors were irradiated with graded doses of 1-6 Gy 200kV X-rays. Cell survival was determined by a colony-forming assay. Markers of differentiation or senescence were: spontaneous and radiation-induced clonal differentiation, which was determined morphologically and by the cellular potential to proliferate in clonal culture, also single-cell beta-galactosidase (beta-gal) staining at pH 6.0; and the secretion of transforming growth factor-beta (TGF-beta1) into the culture medium. Chromosome aberrations were determined as genomic yields of dicentric chromosomes and the excess acentric fragments, scored in Giemsa-stained metaphases, and as partial yields of reciprocal translocations for chromosomes 4, 7 and 9 using the FISH method.


RESULTS
A broad spread was found in the shapes of the survival curves, with SF2 ranging from 0.041+/-0.015 to 0.63+/-0.05. Radiation-induced clonal differentiation as well as the secretion of TGF-beta1 was elevated in radiosensitive samples. With respect to chromosome aberrations, a significant correlation was found between clonogenic survival and radiation-induced excess acentric fragments.


CONCLUSIONS
In the fibroblast cell system, in vitro radiosensitivity is determined not only by processes directly involved in DNA-damage recognition and repair, but also by intracellular signalling cascades, which will lead to differentiation processes.
Rave-Fränk
M
M
Klinik für Strahlentherapie und Radioonkologie, Universität Göttingen, D-37075, Göttingen, Germany. mfraenk@med.uni-goettingen.de
Virsik-Köpp
P
P
Pradier
O
O
Nitsche
M
M
Grünefeld
S
S
Schmidberger
H
H
D016923:Cell Death; D002454:Cell Differentiation; D002455:Cell Division; D002470:Cell Survival; D002478:Cells, Cultured; D016922:Cellular Senescence; D002869:Chromosome Aberrations; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000378:metabolism / Q000528:radiation effects*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D017404:In Situ Hybridization, Fluorescence; D066298:In Vitro Techniques; D008677:Metaphase; D011836:Radiation Tolerance; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000378:metabolism; D014965:X-Rays; D001616:beta-Galactosidase / Q000378:metabolism
D016212:Transforming Growth Factor beta; D001616:beta-Galactosidase