Up-regulation of Lewis enzyme (Fuc-TIII) end plasma-type alpha 1,3fucosyltransferase (Fuc-TVI) expression determines the augmented expression of sialyl Lewis x antigen in non-small cell lung cancer

Sialyl Lewis a and x antigens are well-known tumor-associated antigens expr essed in many cancer tissues. The expression of the genes encoding 5 alpha 1,3fucosyltransferases, which are able to synthesize the sialyl Lewis antig ens, 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 (alpha 1,3/4fucosyltransferas e, Fuc-TIII), were abundantly expressed in lung tissue, and interestingly t hey were markedly up-regulated in the lung cancer tissues of all 20 cases i n comparison with normal lung tissues. Myeloid-type alpha 1,3fucosyltransfe rase (Fuc-TIV) was expressed at an intermediate level but was not up-regula ted in lung cancer tissues. The transcripts for plasma-type alpha 1,3fucosy ltransferase (Fuc-TVI) gene were detected at a very low level but were appa rently up-regulated in cancer tissues. Fuc-TVI was found to exhibit stronge r relative activity for sialyl Lewis x synthesis (almost 6.4-fold that of F uc-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 n ot determined by any of the alpha 1,3-fucosyltransferases, although the exp ression of sialyl Lewis a antigens definitely required the Lewis enzyme. (C ) 1999 Wiley-Liss, Inc.