A sequential in vivo–in vitro study of carcinogenesis induced in the rat brain by ethylnitrosourea

Abstract

THE processes which occur between exposure to a chemical carcinogen and the appearance of a gross tumour, the latent period, are still largely unknown. One approach to investigating how the biological properties of cells are altered during this time is to monitor the behaviour of cells cultured from target organs at different times after carcinogen treatment. A system in which a single dose of a chemical results in a high yield of tumours is a good starting point for such experiments. When pregnant rats are injected with ethylnitrosourea (ENU) almost every one of the progeny develops tumours of the nervous system¹, of which macro- and microtumours of the brain constitute ∼ 60% (predominantly cerebral gliomas²). To investigate the process of carcinogenesis during the latent period, cultures have been prepared from ENU-induced gliomas and from ENU-treated animals at different times before the appearance of such tumours.