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Two Distinct Types of SV40-transformed Human Amnion Cells¹

Sloan-Kettering Institute for Cancer Research [E. V. G., L. R.] and Sloan-Kettering Division, Graduate School of Medical Sciences, Cornell University [J. F.], New York, New York 10021

Human epithelial amnion cells infected in primary culture with simian virus 40 transform to give rise to two morphologically different cells (T and R). R cell foci appear later, after infection, and the proportion of R to T cell foci increases when older amnion cultures are infected. T cells may be easily subcultured by routine trypsinization methods. The more slowly dividing R cells are very resistant to treatment with enzymes and chelating agents, and require special subcultivation procedures. Cultures of both transformed cell types produce SV40; R cell cultures show higher virus titers and contain more virus-producing cells. Chromosome numbers of R cells are near tetraploid in the early stages of cultivation. However, T cells remain in the diploid range for longer periods. R cells do not enter a typical "crisis" stage. They produce more growth than T cells in the cheek pouch of weanling hamsters conditioned with cortisone. It is proposed that the amount of R cell transformation is related to the formation of a population in older uninfected primary cultures with an abnormal genetic constitution.

¹ This investigation was supported in part by National Cancer Institute Research Grant CA-08748.

² Recipient of a research fellowship grant from the Westchester Division of the American Cancer Society. Present address: Biology Department, Pennsylvania State University, University Park, Pa. 19602.

Received 7/14/69. Accepted 8/27/69.