Bara J, Imberty A, Pérez S, Imai K, Yachi A, Oriol R
Mucin Immunochemistry Laboratory, IRSC, Villejuif, France.
Int J Cancer. 1993 Jun 19;54(4):607-13. doi: 10.1002/ijc.2910540414.
MUSE11, DF3 and SM3 MAbs react with a synthetic peptide of 20 amino-acids: VTSAPDTRPAPGSTAPPAHG. This sequence is a tandem repeat domain of the mucin-type glycoprotein coded by the muc-1 gene. MUSE11 and DF3 MAbs immunoreact strongly with mucus cells of the normal surface gastric epithelium of Le(a+b-) non-secretors, but in spite of the peptidic nature of the recognized epitope, the same tissue of Le(a-b+) secretors reacts only after treatment with alpha-fucosidase. These reactions are inhibited by the PNA lectin, which recognizes the T disaccharide antigen (beta Gal 1-3 alpha GalNAc), suggesting that the peptide epitope may be close to the T-saccharide structure. The SM3 MAb reacted on the surface gastric epithelium of all individuals after a more drastic deglycosylation using 20 mM periodate. Computer modeling of the MUC-1 immunoreactive glycopeptide containing the H type-3 trisaccharide alpha Fuc 1-2 beta Gal 1-3 alpha GalNAc- bound to the threonine of the PDTRP-pentapeptide shows that the peptide epitope might be masked when the fucose is positioned over the arginine. Thus, a single fucose linked to the T structure could mask the MUC-1 epitopes. In gastric adenocarcinomas, MUSE11 and SM3 epitopes are expressed in 75% (25/33) and 9% (3/33) respectively, while, after partial deglycosylation by periodate treatment, they are positive in 100% (33/33) and 70% (23/33) of cases, respectively.
MUSE11、DF3和SM3单克隆抗体与一段由20个氨基酸组成的合成肽发生反应：VTSAPDTRPAPGSTAPPAHG。该序列是由粘蛋白-1基因编码的粘蛋白型糖蛋白的串联重复结构域。MUSE11和DF3单克隆抗体与Le(a+b-)非分泌者正常胃表面上皮的黏液细胞发生强烈免疫反应，但尽管所识别的表位具有肽的性质，Le(a-b+)分泌者的相同组织仅在经α-岩藻糖苷酶处理后才发生反应。这些反应被识别T二糖抗原（β半乳糖1-3αN-乙酰半乳糖胺）的PNA凝集素抑制，表明肽表位可能靠近T-糖结构。使用20 mM高碘酸盐进行更剧烈的去糖基化处理后，SM3单克隆抗体在所有个体的胃表面上皮上均有反应。对含有与PDTRP五肽的苏氨酸结合的H3型三糖α岩藻糖1-2β半乳糖1-3αN-乙酰半乳糖胺的MUC-1免疫反应性糖肽进行计算机建模显示，当岩藻糖位于精氨酸上方时，肽表位可能被掩盖。因此，与T结构相连的单个岩藻糖可能会掩盖MUC-1表位。在胃腺癌中，MUSE11和SM3表位分别在75%（25/33）和9%（3/33）的病例中表达，而在经高碘酸盐处理进行部分去糖基化后，它们分别在100%（33/33）和70%（23/33）的病例中呈阳性。
