Reproductive Survival of Explanted Human Tumor Cells after Exposure to Nitrogen Mustard or X Irradiation; Differences in Response with Subsequent Subculture in Vitro

Abstract

Curves for the survival of reproductive capacity of explanted human tumor cells, following exposure to the alkylating agent nitrogen mustard (mustine hydrochloride) or 250-kVp X-rays, were obtained as soon as a satisfactory plating efficiency, i.e., .gtorsim. 10%, was obtained from the tumor cells in vitro (usually within 2-10 wk of explanation). All 6 tumor explants tested became more sensitive to the action of nitrogen mustard on serial subculture; the response of 4 explants which, were X-irradiated with invariant with further subculturing. All but 1 explant yielded survival curves which were extremely similar, with Dq values circa 440-610 rad. One line, from a seminoma, had a Dq of 150 rad. These radiosensitive seminoma cells were most resistant to the action of nitrogen mustard. The increase in sensitivity to nitrogen mustard with serial subculture in vitro was not associated with any change in the proliferative rate of the cells, although it may be associated with an increase in the efficiency of transport.