Quantitative aspects of thymidine uptake into the acid-souble pool of normal and polyoma-transformed hamster cells.

The uptake of thymidine into an acid-soluble pool in normal hamster embryo cells and hamster tumor cells transformed by polyoma virus was studied. It was found that tumor cells exhibited a 4-fold higher capacity than normal cells to incorporate thymidine as phosphorylated products into this pool. This was correlated with a 5to 10-fold higher activity of thymidine kinase in the tumor cell lines. The uptake process was strongly inhibited by the thymidine analog iododeoxyuridine, partially inhib ited by deoxyuridine, and not inhibited by uridine.