Resistance of single tumor cells and their intracellular compartments to lipid peroxidation.

An attempt was made to analyze heterogeneity of tumor populations with respect to potential stability of single cells and their intracellular compartments (lipid-containing refractory granules, RG, and cytoplasmic sites) to lipid peroxidation (LP). LP was initiated by a combined action of hypoxia and u.v.-light and measured by the level of fluorescent product of lipid peroxidation (FPLP) well distinguished from other fluorescent components of the cell. Irrespective of the cell growth stage, RG were found to make a major contribution to the total intensity of FPLP of the cell. However, this contribution was minimal (20 to 30%) in exponentially growing ascites tumor cells and maximal (70 to 90%) in the stationary growing ones. It is noteworthy that in both cases the heterogeneous tumor population has cells with a high stability to inhibitory and cytokilling action of LP. We believe that the approach suggested in this work is of potential importance for experimental and clinical practice since it is highly sensitive for detecting FPLP in single cells, which allows one to reveal various subcellular tumor populations and estimate their stability to LP.