Cancer-associated Colonie Mucin in Cultured Human Tumor Cells and Athymic (Nude) Mouse Xenografts1

Miii-iiisderived from colonie cancers differ immunologically and chem ically from those in normal colonie epithelium. It has been demonstrated that the lectin from the peanut will bind to mucins present in colonie cancers and other neoplastic lesions but not to those from the normal colon. It was hypothesized, therefore, that in transformed colonie epithe lium the glycosylation of mucins occurs differently than in normal epi thelium. To rule out the possibility that the differences in oligosaccharide structure were due to postsecretory degradation, studies were designed to evaluate cancer-associated colonie mucins produced under more con trolled conditions. We studied nine different cancer cell lines first in monolayer culture and then as xenografts in athymic or nude mice. Eight of the nine cell lines in monolayer culture synthesized glycoconjugates that were labeled by fluorescein-conjugated lectins. After injection into nude mice, eight of the nine cell lines produced tumors typical of human colonie cancer, and six of nine secreted mucin. The mucins produced by the xenografts were labeled at fluorescence microscopy by peanut lectin and other lectins, characteristic of what had been seen in other primary human colonie cancers. One cell line, LS174T, produced large amounts of mucin in the xenograft model. Mucin was purified from these tumors and characterized biochemically. It was demonstrated that mucin purified from the xeno grafts bound peanut lectin. Therefore, we have concluded that cancer-associated mucins are pres ent in cultured coloréela! tumor cells. The cancer-associated mucins are also found in nude mouse xenografts, indicating that they are not the result of postsecretory degradation by colonie flora or by tumor cell necrosis. The cell culture and xenograft can therefore be useful for studying the biosynthesis of cancer-associated mucins.