C. Mothersill et al., HIGH-LEVELS OF STABLE P53 PROTEIN AND THE EXPRESSION OF C-MYC IN CULTURED HUMAN EPITHELIAL TISSUE AFTER CO-60 IRRADIATION, Radiation research, 137(3), 1994, pp. 317-322
When explants of human uroepithelium or esophageal epithelium are expo
sed to acute doses of radiation (cobalt-60), the cells which grow out
to form the primary cultures show a number of abnormal features. These
include the development of characteristic nonsenescent. foci. These f
oci have previously been shown to be c-myc positive and to have an abn
ormal, tumor-like ultrastructure. Expression of c-myc and the level of
stable p53 proteins have now been examined in these cultures 2 weeks
after irradiation. Both proteins occurred in dividing cells at the gro
wing edge of the explant and in the foci. The expression of c-myc appe
ared to be correlated with growth. As expected, variation between indi
vidual cultures of normal human cells was noted in the expression of s
table p53 protein. Most control uroepithelial cell cultures were negat
ive, but a small cohort showed a wide range of values. The control cul
tures from the esophageal tissues had high expression of p53, and this
decreased marginally after irradiation. Cells positive for p53 were a
lways in cycle and were usually positive for c-myc as well. It would a
ppear from these results that the expression of c-myc and the stable f
orm of the p53 protein occur in irradiated primary cultures of normal
human cells both in foci which also express a number of abnormalities
and in ''edge'' cells which are dividing. Cultures of unirradiated cel
ls from esophagus and a small number of uroepithelial samples had high
levels of p53. Possible reasons for this are discussed.