Identification of a Non-Specific Inhibitor of (Methyl (3)H)Thymidine Incorporation into DNA of Normal and Pre-Neoplastic Cells.

摘要

Growth in mammalian cells is controlled by a variety of factors, both stimulatory and inhibitory. Bullough et al. (2) first proposed the idea that endogenous mitotic inhibitors may play a role in controlling cellular proliferation. Inhibitors may be tissue-specific (9) or non-specific (for review see Lozzio et al. (5)). Although many inhibitors are proteins of high molecular weights, several low molecular weight inhibitors of ((3)H) thymidine incorporation (and therefore DNA synthesis) have been identified (1,3,6). Unlabelled thymidine has also been noted to be inhibitory (4). This paper describes a non-specific, unstable inhibitor that is found in media conditioned by neoplastic epithelial cells and some normal fibroblasts and inhibits ((3)H) thymidine incorporation into normal and pre-neoplastic cells. The inhibitory activity has not been isolated and could consists of more than one compound. 9 refs., 1 tab.