C. Mothersill et al., PRIMARY EXPLANTS OF HUMAN UROEPITHELIUM SHOW AN UNUSUAL RESPONSE TO LOW-DOSE IRRADIATION WITH CO-60 GAMMA-RAYS, Radiation research, 142(2), 1995, pp. 181-187
Recent results using very low doses of radiation have suggested that t
here is a hypersensitive region where cultures show an enhanced level
of cell killing leading to a non-monotonic survival curve. This effect
has been observed at doses below 2 Gy in mammalian systems and at muc
h higher doses in insect cells, In this paper Re report observation of
the effect in primary human uroepithelial cell cultures, The effect w
as measured using a postirradiation proliferation assay where irradiat
ed explants of standard size were allowed to proliferate for 14 days a
fter exposure to Co-60 gamma irradiation, By 14 days the majority of c
ultures derived from explants irradiated with 2-5 Gy showed little evi
dence of growth inhibition and cell numbers approached or even exceede
d those obtained in the controls, There was, however, a significant re
duction in cell number and growth rate in all cultures exposed to dose
s lower than 1 Gy. Oncoprotein (p53, c-myc, bcl-2, p21 ras) and EGFR e
xpression were also measured in these cultures and were significantly
increased, Morphological evidence of apoptosis was present in all irra
diated cultures at 4 h after exposure, but this persisted for longer p
eriods in cultures exposed to low doses. (C) 1995 by Radiation Researc
h Society