Reversible and irreversible effects of tissue culture on enzyme patterns of spontaneous mouse tumors and mouse and human embryo tissues.

The DNA:protein ratio and enzyme patterns of four spontaneous mouse tumors (one male and one female mammary carcinoma, a muscle sarcoma, and a uterine fibrosarcoma) were determined. Tissue culture cell lines established from these tumors and from mouse embryo and human embryo lung tissues showed quantitative changes in DNA:protein ratio and most of the 13 enzymes studied. Although there were wide variations in enzyme patterns between the tumors and between the embryo tissues, the pattern in tissue culture cells, whatever their origin, tended to be similar. Most of the tumor cell enzyme changes were reversible after reimplantation into syngeneic hosts, with the exception of alkaline phosphatase, which did not reappear in muscle sarcoma and female mammary carcinoma derived from tissue culture cells. In tissue culture, the mitochondrial enzymes succinic dehydrogenase and cytochrome oxidase were particularly affected. Surface enzymes were also altered. Alkaline phosphatase was decreased or lost and 5'-nucleotidase