Characterisation of human cells transformed in vitro by urethane

CELLS derived from several animal species, including mouse^1,2, hamster³ and rat⁴, have been transformed in vitro from the normal to the malignant state by diverse chemical carcinogens. In similar conditions, however, attempts to transform human cells have usually been unsuccessful and as far as we know, such transformation has been reported only once⁵. This was a case of two cell lines treated with urethane, obtained from siblings with von Recklinghausen's disease, a familial disorder transmitted by an autosomal dominant gene, and characterised by multiple fibromas with a high predisposition to malignant transformation in vivo ⁶. Although morphologically altered foci of transformed cells were reported, there was the possibility that a few tumour cells in the original population had been selected for by urethane. Therefore we characterised in detail the urethane-treated and untreated cultures. We have found that human cells can indeed be chemically transformed in vitro.