Published in Cancer Detection and Prevention 2000; 24(1):61-71.

Biosynthesis of Vicia gramineaa Lectinpand Vicia unijuga Lectin Binding Glycoproteins in Human tumor and Non-Tumor Cells, and an Estimation of Epitope Structure

Kunlo Ohyama, PhD, Noboru Uchide, Ryoko Suzuki, Nobuko Iwamoto, Toshio Bessho M.D., PhD 1, Hajime Watanabe, MD,PhD2, Shun Hirakawa, M.D., PhD2, Toshio Yamakawa, PhD

1Department of Biochemistry, School of Pharmacy, Tokyo University of Pharmacy & Life Science,Hachioji, Tokyo, Japan, Yoneya ma Maternity Hospital, Hachioji, Tokyo, 2The First Department ofObstetrics and Gynecology, School of Medicine, Toho University, Ohta-ku, Tokyo, Japan.

Address all correspondence to: Kunjo Ohyama, Ph.D., Department of Biochemistry. School of Pharmacy, Tokyo University ofPharmacy and Life Science, 1432-I Horinouchi, Hachioji, Tokyo 192-03, Japan. Tel; +81-426-76-5792. Fax: +81-426-76-5736.

ABSTRACT We investigated biosynthesis of Vicia graminea lectin (VGA)- and Vicia unijuga lectin (VUA)-binding (Vgu) glycoproteins, which are human malignant tumor-associated antigens, in cultured human tumor and non-tumor cells by pulse-labeling experiments with [35S]-methionine, followed by immunoprecipitation usingimmobilized VUA, SDS-PAGE and autofluorography. It was shown that Vgu glycoproteins synthesized by tumorcells were 15-30 limes greater than those of non-tumor cells. It was also shown that about 40-70% of Vgu glycoproteins synthesized by non-tumor cells were secreted from the cells while more than 80% of the antigen synthesized by tumor cells was not secreted, and that Vgu glycoproteins consisted of multiple molecular species with thesame epitope. To estimate the epitope structure of Vgu glycoproteins, in preliminary experiments we preparedsialoglycoproteins andlor sialoglycopeptides from purified human glycophorin A. Human glycophorins AM and AN(GPs~AM and AN) were treated with Clostridium perfringens neuraminidase to remove all sialic acid residueslinked to carbohydrate chains, with Newcastle disease virus (NDV) to remove α2-3 linked sialic acid residues, andby Edman’s degradation to eliminate N-terminal amino acid of GP-As. Partial or complete desialylation reactionsresulted in disappearance of the reactivity of GP~AM and GP-AN with corresponding antisera and in appearance ofreactivities with VUA and VGA. Elimination of N-terminal amino acid of GP-As also resulted in appearance ofreactivities with VUA. These results show that sialoglycoproteins with similar serological properties of Vgu glycoprotein could be prepared from GP-As, and suggest that the epitope structure of Vgu glycoprotein may be related tothe MN blood type-epitope structure and its sialic acid residues at N-terminal moiety of GP-As.

KEY WORDS: tumor-associated antigen, anti-N lectin, tumor cells, arnnion, chorion laeve, fetal.

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