A comparison of [3H]galactose and [3H]fucose uptake with the morphological and histochemical changes observed in mucous secretion in chemically induced rat colonic carcinoma.

The alterations in carbohydrate metabolism which occur in the distal colon of rats during carcinogenesis induced by dimethylhydrazine were investigated using [3H]galactose and [3H]fucose as glycoprotein precursors. A statistically significant decrease in [3H]galactose uptake was observed in dysplastic epithelia. These findings are consistent with the alterations in mucin composition with predominance of sialomucins shown in these areas by histochemical methods. Furthermore, changes in the gradient of [3H]galactose incorporation along the crypt epithelium were also found in the histological and histochemically non-involved colonic mucosa of dimethylhydrazine-treated rats, as compared with controls. No significant variations were seen in [3H]fucose incorporation. These results correlate well with our previous histochemical observations and are further evidence of the profound alterations in glycoprotein synthesis affecting the whole colonic mucosa during carcinogenesis.