HETEROGENEITY OF THE GROWTH AND METASTATIC BEHAVIOR OF CLONED CELL-LINES DERIVED FROM A PRIMARY RHABDOMYOSARCOMA

Abstract

In order to study the heterogeneity of the metastatic and tumorigenic behaviors of malignant neoplasms, a series of cloned cell lines was isolated from a primary Ni-induced rat rhabdomyosarcoma. The growth characteristics in vitro and in vivo and metastatic capacity following s.c. or i.v. injection of cells were compared to those of the parental cell line. Differences between the cloned cell lines themselves and between the clones and the parental cells were found in the number of metastases provoked by both i.v. and s.c. injections, in the number of cells required to induce s.c. tumors, and in the growth rate of those tumors. In vitro, the doubling times and saturation densities of the different cell lines varied greatly. A direct correlation was observed between the 50% tumoral dose and the initial tumor growth phase. There was a tendency for lines which were highly metastatic after s.c. injection to have a low metastatic capacity after i.v. injection and vice versa. The 2 types of metastasis (spontaneous and experimental) appear therefore to depend on different characteristics of the cells used.