Selective synthesis and accumulation of nuclear non-histone proteins during carcinogenesis of the colon induced by 1, 2-dimethylhydrazine.

The complement of nuclear non-histone proteins in epithelial cells of the colon is progressively altered during the course of carcinogenesis induced by 1, 2-dimethylhydrazine, until finally the nuclear proteins of tumor cells are easily distinguishable from those of the surrounding normal tissue. These changes in nuclear protein compostion reflect earlier differences in the rates of synthesis of individual protein species. Radioisotopic double-labeling experiments show that the synthesis of nuclear proteins of molecular weights 44,000 and 62,000 is selectively accelerated within 4 weeks after administration of the carcinogen, long before any morphological indications of malignancy appear.