Region-specific patterns of mucin reaction demonstrated by paradoxical concanavalin A-staining in normal colonic epithelium and in colorectal cancers induced in rats by 1,2-dimethylhydrazine.

The histochemistry of mucin in normal large intestine and in experimental colorectal cancers induced in Wistar rats with 1,2-dimethylhydrazine was analyzed by modifications of the concanavalin A-horseradish peroxidase method (paradoxical concanavalin A-staining) and high-iron diamine-Alcian blue (pH 2.5) staining (HID-AB). Quantitative analysis of each mucin reaction was done by the use of an image analyzer. Regional variations in the percentage area of "labile class III mucin" were 1 to 50% in the distal colon and 50 to 90% in the proximal colon. Regional variations in the percentage area of sulfated sialomucin were 80 approximately 100% in the distal colon and under 20% in the proximal colon. The percentage area of "labile class III mucin" in primary colorectal cancers showed region-specific variation and that in metastatic colorectal cancers also showed similar region-specific variation of colorectal mucosa where primary tumors were located. In contrast, there were no region-specific mucin reactions for sulfated sialomucin in almost all primary and metastatic colorectal cancers.