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 α1→2fucosyltransferase, α1→3fucosyltransferase, and α1→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 α1→2fucosyltransferase, α1→3fucosyltransferase, and α1→4fucosyltransferase activities of these cell lines were determined. Compared with normal endometrium, uterine endometrial cancer tissues showed significantly higher values of α1→2fucosyltransferase, α1→3fucosyltransferase, and α1→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 α1→2fucosyltransferase and α1→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 α1→4fucosyltransferase activity. These results suggest that the α1→2fucosyltransferase and α1→4fucosyltransferase activities, especially the α1→4fucosyltransferase activity, contribute to the abnormal expression of the Lewis^b antigen in uterine endometrial cancer.