Induction of lactase biosynthesis in the human intestinal epithelial cell line Caco‐2

Abstract

The human colonic adenocarcinoma cell line Caco-2 forms monolayers of differentiated enterocyte-like cells when cultured on permeable supports. After confluency, Caco-2 cells express a number of brush-border enzymes including lactase-phlorizin hydrolase, sucrase-isomaltase and dipeptidylpeptidase IV. We have studied, with particular emphasis on lactase-phlorizin hydrolase, the modulation of biosynthesis of these enzymes by stimulating second messenger systems. Forskolin induced lactase-phlorizin hydrolase synthesis approximately fourfold within 7 h, suppressed sucraseisomaltase synthesis, and had little effect on dipeptidylpeptidase IV. Dibutyryl-CAMP, 8-bromocAMP and vasoactive intestinal peptide also increased lactase-phlorizin hydrolase biosynthesis, indicating c-AMP dependent regulation. The induction of lactase-phlorizin hydrolase biosynthesis could be inhibited by actinomycin D and was preceded by a fourfold increase in lactase-phlorizin hydrolase mRNA levels, suggesting transcriptional control. Phorbol 12-myristate 13-acetate had an inhibitory effect on brush-border enzyme synthesis, in particular on sucrase-isomaltase, and blocked the forskolin-induced biosynthesis of lactase-phlorizin hydrolase. Lactase-phlorizin hydrolase synthesis was also inducible by hydrocortisone, but maximal induction required at least 3 days during which time sucrase-isomaltase synthesis diminished. The results indicate opposite regulation of lactase-phlorizin hydrolase and sucrase-isomaltase via cAMP and corticosteroids, and suggest that the Caco-2 cell line can serve as a model system to study aspects of the humoral regulation of human intestinal brush-border enzymes in cell culture.The human epithelial cell line Caco-2 has been established as a model system to study various aspects of intestinal epithelial cell biology including the synthesis of brushborder enzymes, protein trafficking, epithelial cell polarity (Zweibaum et al., 1991 ;Hauri and Matter, 1991 ;Louvard et al., 1992;Rodriguez-Boulan and Powell, 1992) and transepithelial transport (Thwaites et al., 1993). Although derived from a colonic adenocarcinoma, Caco-2 cells form monolayers of polarized cells on permeable supports and after confluency spontaneously express a number of features that are characteristic for differentiated small intestinal enterocytes rather than large intestinal colonocytes. As it has not been possible to establish non-transformed intestinal epithelial cell lines exhibiting a differentiated phenotype, Caco-2 remains the most promising cell line with which to study small intestinal functions in culture.Among other brush-border enzymes (Howell et al., 1992), Caco-2 cells express lactase-phlorizin hydrolase (LPH;Semenza, 1981Semenza, , 1986 Montgomery et al., 1991;Naim, 1993) which is synthesized as a 200-kDa high-man-

In vitro digestion and lactase treatment influence uptake of quercetin and quercetin glucoside by the Caco-2 cell monolayer

“…Addition of lactose and forskolin, a specific inducer of lactase [29], to Caco-2 cells did not significantly increase lactase activity of Caco-2 cells. The lactase activity of all cells ranged from 2–4 mU/mg protein in all treatments.…”

“…The compound forskolin induced lactase phlorizin hydrolase activity four-fold in Caco-2 cells [29]. In weanling rats, lactose consumption increased lactase activity in the jejunum by three-fold [30].…”

Pathogenesis of Human Enterovirulent Bacteria: Lessons from Cultured, Fully Differentiated Human Colon Cancer Cell Lines

“…In addition, a subapical cell compartment seems to function as a docking platform for vesicles containing functional proteins (98). Parental Caco-2 cells and clones have also been used to identify the mechanisms underlying the sorting and surface delivery of apical and basolateral proteins in human enterocytes (99)(100)(101)(102)(103)(104)(105)(106)(107) and to find out how functional intestinal proteins take their place in cell membrane domains, including brush border-associated functional proteins such as SI (82,84,86,90,94,100,106,(108)(109)(110)(111)(112)(113)(114), AP (110,111), lactasephlorizin hydrolase (108,115), maltase-glucoamylase (108), APN (90,108,111), DPP IV (82,90,100,108,(116)(117)(118)(119)(120)(121), angiotensin I-converting enzyme (108), ␣-glucosidase (122), p-aminobenzoic acid peptide hydrolase (108), SGLT1, GLUT1, GLUT2, GLUT3, and GLUT5 (123)(124)…”

Caco-2 cell disaccharidase activities are unaffected by gestational hormones

“…These cells have been characterized extensively and, upon reaching confluence, have been shown to be highly polarized and have intact tight junctions, a well-developed apical brush border, and associated hydrolases (Mehran et al 1996;Pinto et al 1983). In the one previous report using Caco-2 cells, LPH synthesis was induced by hydrocortisone, whereas sucrase-isomaltase activity diminished (Hauri et al 1994). The present study is thus the first to analyze disaccharidase activities in response to progesterone and estrogen over an extended period in Caco-2 cells.…”

“…Under standard culture conditions, these cells spontaneously exhibit differentiation typical of absorptive enterocytes (Pinto et al 1983). Furthermore, Caco-2 cell expression of LPH can be modulated in vitro (Hauri et al 1994;Ziambaras et al 1996). In the present study, we examined the effect of progesterone and estrogen on lactase and sucrase activity using Caco-2 cells at confluency.…”