Although a specific diagnosis may not be possible in some cases, we believe that knowledge of certain pathologic and computed tomographic features should lead to optimal diagnosis, therapy, and prognosis.
SUMMARYWe set out to determine the expression profiles of glycoproteins possessing N-acetyllactosamine, a precursor carbohydrate of sialyl Le x , during colorectal cancer development. We immunohistochemically analyzed the distribution of N-acetyllactosamine as well as of 4GalT-I, a member of the 1,4-galactosyltransferase family responsible for N-acetyllactosamine biosynthesis, in normal mucosa and in adenoma and carcinoma of the human colorectum. Using monoclonal antibody H11, N-acetyllactosamine was barely detectable in the normal mucosa. In low-grade adenoma, however, N-acetyllactosamine was weakly but definitely expressed on the cell surface, and its expression level was moderately increased in high-grade adenoma and markedly increased in carcinoma in situ as well as in advanced carcinoma. To detect 4GalT-I, we used a newly developed polyclonal antibody (designated A18G), which is specific for the stem region of human 4GalT-I. Faint expression of 4GalT-I was detectable in normal mucosa, and the expression level was moderately increased in low-grade adenoma and in high-grade adenoma and markedly increased in carcinoma in situ and advanced carcinoma. The expression of N-acetyllactosamine was highly correlated with the expression of 4GalT-I in these tumor cells. These results indicate that the expression level of 4GalT-I is apparently enhanced during tumorigenesis in the colorectum and that 4GalT-I mostly directs the carcinoma-associated expression of N-acetyllactosamine on the colorectal tumor cell surface. (J Histochem Cytochem 47:1593-1601, 1999)
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