Intercellular communication and tissue growth

Summary Three cancer cell strains that fail to make permeable membrane junctions were tested for ability to transfer an endogenous hypoxanthine derivative from cell to cell. The cells of these strains, loaded with³H-hypoxanthine, were grown in contact with cells from a mutant line incapable of incorporating exogenous hypoxanthine. The transfer of the³H-hypoxanthine derivative to the mutant cells was determined by radio-autography and, in the same preparations, the presence of permeable membrane junctions was determined by intercellular fluorescein tracer diffusion and electrical measurement. The cells of the three strains showed no transfer of hypoxanthine derivative to contiguous mutant cells; the cells that make permeable junctions did show such transfer, under the same conditions.In contrast to this contact-requiring mode of transfer, a contact-independent transfer phenomenon was observed with these three cancer cell strains.