The isolation and characterization of colorectal epithelial cell lines at different stages in malignant transformation from familial polyposis coli patients.

The genetic disease familial polyposis coli (hereditary adenomatosis of the colon and rectum) provides an excellent model for the study of tumour progression in the large bowel. We have isolated and characterized four epithelial cell lines from colorectal tumours from polyposis coli patients. These cell lines are grown on collagen-coated Petri dishes in the presence of mouse 3T3 feeder cells in medium containing 20% foetal bovine serum. Of these cell lines three were isolated from premalignant adenomas and one from an adenocarcinoma. All four lines have a characteristic cuboidal epithelial morphology, and their epithelial origin was confirmed by positive staining with a monoclonal antibody which reacts specifically with the keratin filaments of simple epithelia. The adenoma-derived lines display ultrastructural features characteristic of colonic epithelium including desmosomes, microvilli and mucin droplets. One of the adenoma-derived cell lines, designated PC/AA, has retained differentiated functions in culture, namely mucin production, after 21 in vitro passages. PC/AA has a karyotype of 46, XY with no detectable chromosome rearrangements. The adenoma-derived lines could be passaged from clumps of cells but not from single cells even in the presence of 3T3 feeder cells. The carcinoma-derived line, designated PC/JW, could however grow from single cells in the presence of a feeder layer. The one premalignant adenoma-derived line tested so far, PC/AA, did not produce tumours in athymic nude mice. In contrast, the carcinoma-derived line, PC/JW was tumorigenic in athymic nude mice. PC/JW produced moderately well-differentiated tumours which were histologically similar to the adenocarcinoma from which the cell line was isolated. PC/JW has a near-diploid chromosome number with an isochromosome (1q), an isochromosome (14q) and an (Xp; 17q) translocation. Unidentified marker chromosomes were present in a few cells. The features at present which distinguish the carcinoma-derived line from the adenoma-derived lines are tumorigenicity, growth from single cells and chromosomal abnormalities. The isolation and characterization of differentiating human epithelial cell lines at different stages in malignant transformation provide an opportunity to examine the cellular and molecular mechanisms controlling tumour progression in the large intestine, and to obtain an insight into the multistep process of human epithelial carcinogenesis.