Up-regulation of Lewis enzyme (Fuc-TIII) and plasma-type alpha1,3fucosyltransferase (Fuc-TVI) expression determines the augmented expression of sialyl Lewis x antigen in non-small cell lung cancer.

Abstract

Sialyl Lewis a and x antigens are well-known tumor-associated antigens expressed in many cancer tissues. The expression of the genes encoding 5 alpha1,3fucosyltransferases, which are able to synthesize the sialyl Lewis antigens, was examined in normal and cancerous lung tissues of patients with non-small cell lung carcinoma. In all 20 cases examined, the transcripts only for the Lewis gene, encoding the Lewis enzyme (alpha1,3/4fucosyltransferase, Fuc-TIII), were abundantly expressed in lung tissue, and interestingly they were markedly up-regulated in the lung cancer tissues of all 20 cases in comparison with normal lung tissues. Myeloid-type alpha1,3fucosyltransferase (Fuc-TIV) was expressed at an intermediate level but was not up-regulated in lung cancer tissues. The transcripts for plasma-type alpha1,3fucosyltransferase (Fuc-TVI) gene were detected at a very low level but were apparently up-regulated in cancer tissues. Fuc-TVI was found to exhibit stronger relative activity for sialyl Lewis x synthesis (almost 6. 4-fold that of Fuc-TIII). The amount of sialyl Lewis x antigen on mucins in the lung cancer tissues was found to be determined by both enzymes, the Lewis enzyme (Fuc-TIII) and Fuc-TVI. However, the amount of the sialyl Lewis a antigens was not determined by any of the alpha1,3-fucosyltransferases, although the expression of sialyl Lewis a antigens definitely required the Lewis enzyme.