MEASUREMENT OF CELL-PROLIFERATION BY LABELING OF DNA WITH STABLE ISOTOPE-LABELED GLUCOSE - STUDIES IN-VITRO, IN ANIMALS, AND IN HUMANS

A method for measuring DNA synthesis and, thus, cell proliferation, in vivo is presented, The technique consists of administering [6,6-H-2(2 )]Glc or [U-C-13]Glc, isolating genomic DNA, hydrolyzing enzymatically to free deoxyribonucleosides, and derivatizing for GC-MS analysis of dA or dG isotopic enrichments, or both, Comparison of dA or dG to extr acellular Glc enrichment (with a correction for intracellular dilution ) reveals the fraction of newly synthesized DNA, by application of the precursor-product relationship, Thus, the technique differs from the widely used [H-3]thymidine or BrdUrd techniques in that the de novo nu cleotide synthesis pathway, rather than the nucleoside salvage pathway , is used to label DNA; the deoxyribose rather than the base moiety is labeled; purine rather than pyrimidine deoxyribonucleosides are analy zed; and stable isotopes rather than radioisotopes are used, The metho d is applied here in vitro to the growth of HepG(2) and H-9 cells in c ulture; in animals to proliferation of intestinal epithelium, thymus, and liver; and in humans to granulocyte turnover in blood, In all inst ances, measured cell proliferation kinetics were consistent with expec ted or independently measured kinetics, The method has several advanta ges over previously available techniques for measuring cell turnover, involves no radioactivity or potentially toxic metabolites, and is sui table for use in humans, The availability of a reliable and safe metho d for measuring cell proliferation in humans opens up a number of fund amental questions to direct experimental testing, including basic prob lems related to cancer, AIDS, and other pathologic states.