title: Alkaline phosphatase and peptidase activities in Caco-2 cells: differential response to triiodothyronine.
abstract: Caco-2 cell human colon adenocarcinoma cell line was used to study the hormonal regulation of small intestinal epithelial cell differentiation. We had previously shown that insulin-transferrin-selenium and triiodothyronine (5 x 10(-8) M)-supplemented medium can best replace serum after 2 days of culture for both the maintenance and differentiation of Caco-2 cells. The present study demonstrates that precoating petri dishes with complete serum allows the growth and differentiation of Caco-2 cells seeded directly in serum-free medium. On the other hand, precoating with dialyzed serum inhibits alkaline phosphatase and dipeptidyl-dipeptidase IV activities by more than 50%. The results obtained with complete serum-precoated culture plates indicate that there is no synergy between insulin and triiodothyronine because cells maintained in transferrin-selenium and triiodothyronine-supplemented medium, with or without insulin, express comparable enzyme activities. Moreover, large increases in alkaline phosphatase and dipeptidyl-dipeptidase IV activities were observed when triiodothyronine was added to the culture medium by the time confluency was reached. In contrast, gamma-glutamyltransferase was lowered to a greater extent when triiodothyronine was present from the beginning of culture. These findings show that triiodothyronine preferentially stimulates alkaline phosphatase and dipeptidyl-dipeptidase IV activities during the differentiation period whereas it selectively inhibits gamma-glutamyltransferase during the proliferation phase. Triiodothyronine acts in a dose-dependent manner.
authors.affiliation: Department of Physiology, Faculty of Medicine, University of Montréal, Québec, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Jumarie
authors.forename: C
authors.initials: C
authors.lastname: Malo
mesh_terms: D000230:Adenocarcinoma / Q000201:enzymology* / Q000473:pathology; D000469:Alkaline Phosphatase / Q000378:metabolism*; D002450:Cell Communication / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D003110:Colonic Neoplasms / Q000201:enzymology* / Q000473:pathology; D016895:Culture Media, Serum-Free; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D014284:Triiodothyronine / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D005723:gamma-Glutamyltransferase / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D016895:Culture Media, Serum-Free; D007328:Insulin; D014284:Triiodothyronine; D005723:gamma-Glutamyltransferase; D000469:Alkaline Phosphatase; D018819:Dipeptidyl Peptidase 4