Insulin controls key steps of carbohydrate metabolism in cultured HT29 colon cancer cells

Abstract

Effects of insulin on key steps of carbohydrate metabolism were investigated in cultured HT29 colon cancer cells by two different approaches, i.e. incubation of the cells either in the absence or in the presence of glucose in the medium. In glucose-deprived cells, insulin decreased glycogen breakdown, but did not affect polysaccharide levels when glucose was present. Glycogen synthase became activated after insulin treatment in both conditions, even though the activation was more evident when glucose was omitted. No effect on glycogen phosphorylase activity was evident under our experimental conditions. In cells incubated with glucose, the hormone stimulated in a dose-dependent manner the rates of glucose uptake and lactate release. Concomitantly with the increase in glycolytic rate, insulin caused a strong increase in fructose 2,6-bisphosphate. This effect was not observed in the absence of glucose. It is concluded that the carbohydrate metabolism of cultured HT29 cells responds to insulin, making this biological model suitable for investigations in vitro on the mechanism of insulin action.

Alginate–C18 Conjugate Nanoparticles Loaded in Tripolyphosphate-Cross-Linked Chitosan–Oleic Acid Conjugate-Coated Calcium Alginate Beads as Oral Insulin Carrier

“…The cytotoxicity of insulin-loaded ASAN and insulin-loaded AC18N was evaluated in vitro with HT-29 cells using the MTT assay. , HT-29 cells (passage 6) were plated onto 96 well plates (Nunc, Denmark) at a density of 5 × 10 4 cells/well and allowed to attach overnight in the incubator. Following the removal of MEM, the cells were incubated with nanoparticle samples (10 mg in 0.5 mL of phosphate buffer saline, pH 7.4 (PBS)) for 24 h. The cells were then washed and incubated with 20 μL of 3-(4,5-dimethylthiazol-2-thiazolyl)-2,5-diphenyl-2 H -tetrazolium bromide (MTT; Sigma-Aldrich, Germany; 5 mg/mL in PBS) for 4 h in the absence of light.…”

Phosphorylation of protein kinase B, the key enzyme in insulin-signaling cascade, is enhanced in linoleic and arachidonic acid–treated HT29 and HepG2 cells

“…In the present study, human colon adenocarcinoma (HT29) and hepatocellular carcinoma (HepG2) cell lines were used as in vitro systems to study whether alterations of phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn) fatty acid composition alter insulin-induced AKT activation/phosphorylation. Both cell lines express a functional insulin pathway [22,23]. Although the gastrointestinal tract is the main target of insulin, it is where nutrients are processed and absorbed.…”

Involvement of ornithine decarboxylase in the control of proliferation of the HT29 human colon cancer cell line. effect of vasoactive intestinal peptide on enzyme activity

“…HT29 cells possess receptors to VIP (Laburthe et al, 1978), insulin (Chard et al, 1981 and alpha2-adrenergic agonists . Stimulation of these receptors is efficient in controlling carbohydrate metabolism in these cells (Rousset et al, 198 1 ;Denis et al, 1986~;Babia et al, 1989). Exposure of HT29 cells to VIP results in a strong activation of adenylate cyclase followed by a rapid increase in the cAMP level (Laburthe et al, 1978;Rousset et al, 1981).…”