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 Google Scholar Google Scholar Articles by Rubin, H. Articles by Arnstein, P. Search for Related Content PubMed PubMed Citation Articles by Rubin, H. Articles by Arnstein, P.

Dynamics of Tumor Growth and Cellular Adaptation after Inoculation into Nude Mice of Varying Numbers of Transformed 3T3 Cells and of Readaptation to Culture of the Tumor Cells¹

Department of Molecular Biology and Virus Laboratory, University of California, Berkeley, California 94720 [H. R., B. M. C.], and National Cancer Institute, NIH, Bethesda, Maryland 20205 and California Department of Health Services, Berkeley, California 94704 [P. A.]

Decimal dilutions containing 5 x 10⁵ to 5 x 10¹ cells were inoculated s.c. into nude mice and the course of tumor development was recorded. The highest concentration of cells produced rapidly growing poorly differentiated sarcomas within 2–3 weeks of their inoculation. Upon explantation the resultant tumors yielded cells which multiplied on plastic almost as rapidly as did their progenitors used to initiate the tumors, and had as high a colony forming efficiency in agar as long as tryptose phosphate broth was omitted from the agar medium. Tumors initiated by the lower concentrations of cells were disproportionately delayed in their appearance and tended to increase in size at a low rate. At least one tumor regressed and one which apparently regressed appeared again at a later time. These changes are characteristically described under the rubric of tumor regression. Host reactive cells such as neutrophils, eosinophils, macrophages, and fibroblasts were observed in some tumors. One of the tumors was a low grade hemangiosarcoma, another a well-differentiated fibrosarcoma, and the rest poorly differentiated sarcomas. Cells from two tumors initiated by 500 and 5000 cells multiplied slowly in early passages in culture, particularly when seeded at low densities at which they appeared to sustain cumulative damage even when multiplying. In later passages, the "low dose" tumor cells gained the capacity to multiply in culture after seeding at low densities, but it took up to 50 cell generations to reach this capacity. The loss of grwoth capacity on plastic of cells from the low dose tumors and its subsequent restoration by passaging in culture may provide a quantitative method for analyzing the type of cellular change which underlies tumor progression.

¹ This work was supported in part by USPHS Grant CA 15744 and in part by a grant from the U.S. Department of Energy. Office of Environment under Contract AT03-79EV10277.

² To whom requests for reprints should be addressed.

Received 8/ 6/85. Revised 11/18/85. Accepted 12/11/85.