Organ culture-cell culture system for studying multistage carcinogenesis in respiratory epithelium. [Mice]

An organ culture-cell culture system was used to demonstrate carcinogen dose-dependent transformation of tracheal epithelial cells in vitro. Tracheal explants were exposed to MNNG (N-methyl-N/sup 1/-nitro-N-nitrosoguanidine) in organ culture. Outgrowths from these explants provided epithelial cell cultures. The numbers of long term epithelial cell cultures and cell lines that were established per explant increased as MNNG exposure concentration increased. At the present time, more cell lines derived from explants exposed to the highest MNNG concentration have produced palpable tumors than cell lines derived from explants exposed to lower MNNG concentrations. No cell lines were established from primaries derived from control explants. TPA (12-0-tetradecanoyl-phorbol-13-acetate), stimulates DNA synthesis in tracheal epithelium in organ culture in a manner simular to that described for mouse skin. Short exposures to TPA not only stimulated DNA synthesis earlier, but the stimulation was greater than that obtained with continuous exposure. At the present time, exposure of tracheal organ cultures to MNNG followed by TPA has resulted in an enhanced production of morphologically altered cells in primary epithelial cell cultures, than exposure to either agent alone.