Enzymatic basis for the accumulation of Lewis(b) antigen in uterine endometrial cancer

In order to clarify the mechanism of the abnormal expression of Lewis(b) antigen, which was specific for uterine endometrial cancer tissue, the activities of alpha 1-->2fucosyltransferase, alpha 1-->3fucosyltransferase, and alpha 1-->4fucosyltransferase in normal endometrial tissues and uterine endometrial cancer tissues were determined. Further, an immunocytochemical study of the expression of blood group-related carbohydrate antigens in 6 cultured cell lines derived from various gynecologic malignant tumors was performed and the alpha 1-->2fucosyltransferase, alpha 1-->3fucosyltransferase, and alpha 1-->4fucosyltransferase activities of these cell lines were determined. Compared with normal endometrium, uterine endometrial cancer tissues showed significantly higher values of alpha 1-->2fucosyltransferase, alpha 1-->3fucosyltransferase, and alpha 1-->4fucosyltransferase activities. The specifically strong expression of type I carbohydrate chains, particularly the Lewis(b) antigen, was recognized in cultured cell lines derived from uterine endometrial cancer. Compared with those cell lines derived from uterine cervical cancer and ovarian cancer, the cultured cell lines derived from uterine endometrial cancer showed higher activities of alpha 1-->2fucosyltransferase and alpha 1-->4fucosyltransferase, which are enzymes related to the synthesis of Lewis(b) antigen. The cell lines derived from uterine endometrial cancer showed specifically high values of alpha 1-->4fucosyltransferase activity. These results suggest that the alpha 1-->2fucosyltransferase and alpha 1-->4fucosyltransferase activities, especially the alpha 1-->4fucosyltransferase activity, contribute to the abnormal expression of the Lewisb antigen in uterine endometrial cancer.