This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Haber, D. A. Articles by Thilly, W. G. Search for Related Content PubMed PubMed Citation Articles by Haber, D. A. Articles by Thilly, W. G.

Cell Density Dependence of Focus Formation in the C3H/10T1/2 Transformation Assay¹

Department of Nutrition and Food Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 [D. A. H., W. G. T.]; Harvard Medical School, Boston, Massachusetts 02115 [D. A. F.]; and McArdle Laboratory for Cancer Research, University of Wisconsin, Madison, Wisconsin 53706 [W. S. D.]

Some of the dynamics of neoplastic transformation in vitro have been studied with the use of benzo(a)pyrene as the carcinogen in the C3H/10T1/2 morphological transformation assay. Experiments that involved the dispersion of cells into new culture dishes at various times after carcinogen treatment have shown that no change in the fraction of potentially transformed cells occurs while cultures grow to form a confluent monolayer, that little or no change in the fraction of potentially transformed cells occurs for approximately 3 weeks after confluence is attained, and that this fraction increases rapidly some 7 weeks after BP treatment. When confluent benzo(a)pyrene-treated cultures are dispersed in new culture dishes prior to the onset of growth toward focus formation, the formation of transformed foci is suppressed at high cell densities of seeding. This phenomenon is independent of the total number of divisions undergone by cells after treatment. We suggest that phenotypic expression of morphological transformation is dependent on colony interactions in the C3H/10T1/2 system, which we do not yet understand, but which are independent of time posttreatment expressed either in cell generations or absolute time.

¹ This work was supported in part by Grants NCI 50RO1 and CA 15010-02ET from the National Cancer Institute, Grant NIEHS 5P01 ES 00597 from The National Institute of Environmental Health Sciences, and by the Massachusetts Institute of Technology Undergraduate Research Opportunities Program.

Received 6/21/76. Accepted 2/25/77.

This article has been cited by other articles:

				M. Chow and H. Rubin Coculturing diverse clonal populations prevents the early-stage neoplastic progression that occurs in the separate clones PNAS, January 4, 2000; 97(1): 174 - 178. [Abstract] [Full Text] [PDF]

				M. Chow and H. Rubin Clonal dynamics of progressive neoplastic transformation PNAS, June 8, 1999; 96(12): 6976 - 6981. [Abstract] [Full Text] [PDF]