Malignant properties and DNA content of daughter clones from a mouse fibrosarcoma: differentiation between malignant properties.

Freshly isolated cones of high cloning efficiency from a mouse fibrosarcoma were examined for DNA content, cell size, protein content, and malignant characteristics such as artificial lung-colony-forming ability, s.c. tumour take, host survival, and spontaneous metastatic ability. These malignant characteristics and other cell properties were heterogeneous among these clones; the malignant characteristics could vary and were not "all or none" in their nature. The higher the DNA content or the larger the cell volume, the higher the malignancy in terms of artificial lung-colony forming, efficiency, s.c. tumour take, and host survival. Despite variability of each parameter, the ratio of DNA content to cell size or protein content remained constant through these variations: the increased DNA paralleled increased protein and increased cell volume. The increased DNA was correlated with the more malignant characteristics of local growth and lung-colony-forming efficiency. Spontaneous metastasis to the lung was totally different from the local growth abilities; the small-cell clone produced more metastases. The graded nature of malignant properties and the differentiation between local growth and metastatic potential among the daughter clones indicate that malignancy reflects a complex moiety of cell properties.