Boland C R, Montgomery C K, Kim Y S
Proc Natl Acad Sci U S A. 1982 Mar;79(6):2051-5. doi: 10.1073/pnas.79.6.2051.
The binding of fluorescein isothiocyanate (FITC)-conjugated lectins to mucin in the human colon was studied by using fluorescence microscopy. In normal mucosa, lectins that preferentially bind to exposed N-acetyl-galactosamine residues (Dolichos biflorus agglutinin and soybean agglutinin) bound selectively to the goblet cell mucin of well-differentiated cells in the upper colonic crypt. By contrast, lectins that require exposed non-reducing galactose residues for binding (Ricinus communis agglutinin1 and Bauhinia purpurea agglutinin) preferentially labeled the mucin of less-differentiated goblet cells located in the lower portion of the colonic crypt. The lectin derived from Arachis hypogaea (peanut agglutinin) has a high affinity for a carbohydrate structure not normally exposed in human tissues. This lectin did not label the goblet cell mucin in the normal colon. However, the mucin was labeled in all 21 colon cancer specimens examined. Additionally, the nonmalignant epithelium immediately adjacent to colon cancer (termed "transitional mucosa") also contained goblet cell mucin that was labeled by FITC-peanut agglutinin. Three conclusions may be drawn from the selective binding characteristics of FITC-lectins to colonic mucins. First, an alteration in the exposed, nonreducing carbohydrate residues occurs in human colonic mucin during the process of goblet cell differentiation. Second, an exposed carbohydrate structure that is not normally present in human tissues is expressed in the mucin produced by malignant colonic epithelium. Third, the presence of the cancer-associated carbohydrate structure in the mucin of transitional mucosa suggests that this tissue may be in the process of early malignant transformation.
利用荧光显微镜研究了异硫氰酸荧光素（FITC）偶联凝集素与人结肠粘蛋白的结合情况。在正常黏膜中，优先结合暴露的N-乙酰半乳糖胺残基的凝集素（双花扁豆凝集素和大豆凝集素）选择性地结合于结肠上段隐窝中分化良好细胞的杯状细胞粘蛋白。相比之下，需要暴露的非还原半乳糖残基才能结合的凝集素（蓖麻凝集素1和紫羊蹄甲凝集素）则优先标记位于结肠隐窝下部的分化程度较低的杯状细胞的粘蛋白。源自落花生（花生凝集素）的凝集素对正常人体组织中通常不暴露的碳水化合物结构具有高亲和力。这种凝集素在正常结肠中不标记杯状细胞粘蛋白。然而，在所检查的所有21个结肠癌标本中，粘蛋白都被标记。此外，紧邻结肠癌的非恶性上皮（称为“过渡黏膜”）也含有被FITC-花生凝集素标记的杯状细胞粘蛋白。从FITC-凝集素与结肠粘蛋白的选择性结合特性可得出三个结论。第一，在杯状细胞分化过程中，人结肠粘蛋白中暴露的非还原碳水化合物残基发生了改变。第二，恶性结肠上皮产生的粘蛋白中表达了一种正常人体组织中不存在的暴露碳水化合物结构。第三，过渡黏膜粘蛋白中存在与癌症相关的碳水化合物结构表明该组织可能正处于早期恶性转化过程中。
