Clonal analysis of sucrase-isomaltase expression in the human colon adenocarcinoma Caco-2 cells

• Published in: Biochemical journal Vol. 280; no. 3; pp. 599 - 608
• Main Authors: BEAULIEU, J.-F, QUARONI, A
• Format: Journal Article
• Language: English
• Published: Colchester Portland Press 15.12.1991
• Subjects: Adenocarcinoma - enzymology; Adenocarcinoma - genetics; Aminopeptidases - isolation & purification; Antibodies, Monoclonal; Biological and medical sciences; Clone Cells; Epidermal Growth Factor - metabolism; Fluorescent Antibody Technique; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation, Neoplastic; Humans; Molecular and cellular biology; Molecular genetics; RNA, Messenger - metabolism; Sucrase-Isomaltase Complex - genetics; Sucrase-Isomaltase Complex - isolation & purification; Sucrase-Isomaltase Complex - metabolism; Transforming Growth Factors - metabolism; Tumor Cells, Cultured; Human; Oligo-1,6-glucosidase; Molecular processing; Enzyme; Secretion; Transforming growth factor; Biological marker; Cell differentiation; Gene expression; Regulation(control); Epidermal growth factor; Cell line; Tumor; Colon
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj2800599

To investigate the biosynthetic basis for the mosaic expression of brush border enzymes in confluent Caco-2 cells, a human colon carcinoma cell line exhibiting characteristics of adult small intestinal enterocytes, we have obtained a series of clones differing markedly in their growth rates, amounts of transforming growth factor-alpha/epidermal growth factor-like activity released into the culture medium, and sucrase-isomaltase (SI) activity. Other intestinal markers (aminopeptidase N, dipeptidylpeptidase IV, lactase, alkaline phosphatase and 'crypt cell antigen') displayed a much more limited variability in expression, suggesting that the Caco-2 cell clones we have obtained did not differ in their overall ability to differentiate. Immunofluorescence staining, metabolic labelling with radioactive methionine and hybridization analysis of SI mRNA abundance were used to investigate SI synthesis and its regulation in clones endowed with low, intermediate or high sucrase activity. The results obtained have demonstrated heterogeneous SI expression, even in clonal cell lines, and a negative correlation between SI expression and growth factor concentrations in the culture medium, suggesting an autocrine regulation of cell proliferation and differentiation in confluent Caco-2 cells. Pulse-chase experiments using the two clones endowed with the lowest and highest levels of SI activity, followed by immunoprecipitation of labelled SI with epitope-specific antibodies and SDS/PAGE analysis, suggested that both transcriptional and post-translational mechanisms play a role in the regulation of SI expression in intestinal cells.