Cytokinetics of Heteroploid Tumor Subpopulations by Combined Autoradiographic Imaging and Feulgen Densitometry

Abstract

Traditional autoradiographic methods for analysis of the cell cycle kinetics of tumors have been limited to estimation of mean phase transit-times and their dispersion in the population as a whole. This obscures the proliferative heterogeneity which may exist among subpopulations. In human tumors where polyploidy and aneuploid variants frequently co-exist, such measurements do not relate to the cytokinetic behavior of the distinct ploidy lineages. An important objective has therefore been to resolve their independent proliferative contributions. This has posed some formidable problems: In populations of uniform ploidy the cycle phase distribution may be resolved from statistical treatment of DNA distributions obtained by flow cytofluorometry or scanning densitometry (1). However, in mixed polyploid/aneuploid systems such a phase deconvolution of subpopulations is not amenable to precise methods due to extensive overlap of their DNA content ranges in the various cycle phases. It is the purpose to outline an approach for resolving the phase distribution and compartmental turnover kinetics of subpopulations based upon automated imageanalysis of ³HTdR labeling and Feulgen densitometry in autoradiographs. The technical aspects of the methodology have been reported (4–6).