C Q Xia1, W C Shen. 1. Department of Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles 90089-9121, USA.
Abstract
PURPOSE: To investigate the effect of tyrphostin 8 (T-8), a GTPase inhibitor, on transferrin receptor (TfR)-mediated transcytosis of insulin-transferrin (In-Tf) conjugate in cultured enterocyte-like Caco-2 cells and on gastrointestinal (GI) absorption of In-Tf in streptozotocin (STZ)-induced diabetic rats. METHODS: Caco-2 cells and diabetic rats were used as in vitro and in vivo models, respectively. TfR-mediated transcytosis was measured using 125I-In-Tf. The absorption of insulin in diabetic rats was demonstrated by the hypoglycemic effect. Rat blood glucose level was determined using a ONE TOUCH blood glucose monitoring system. RESULTS: T-8 increased apical-to-basolateral transport of In-Tf conjugate by enhancing TfR-mediated transcytosis in filter-grown Caco-2 cell monolayer, and this enhancement was higher and faster than the previously reported brefeldin A (BFA)-induced effect. The measurement of transepithelial electrical resistance (TEER) during the transport study showed that T-8 was less destructive on the cell tight junction than BFA. The GI absorption of In-Tf was evaluated by its hypoglycemic effect after oral administration in STZ-induced diabetic rats. The glucose-lowering effect of orally administered In-Tf in STZ-induced diabetic rats was improved by either T-8 or BFA. However, the effect of T-8 was more potent than that of BFA, especially at 7 h after administration. Either non-conjugated insulin or insulin-human serum albumin (In-HSA) conjugate by itself or in combination with T-8 did not show any hypoglycemic effect after oral administration, indicating that T-8-enhanced hypoglycemic activity of In-Tf was due to a selective enhancement of TfR-mediated transcytosis. CONCLUSIONS: Our data indicated that T-8 could be used to increase the GI absorption of insulin as a transferrin conjugate. T-8, as an enhancer of TfR-mediated transcytosis, is better than the previously reported BFA. T-8 produces a higher increase on the transport of In-Tf and a lower toxicity on epithelial cells. Our findings provide an alternative approach to promote the GI absorption of insulin, as well as other peptide or protein drugs.
PURPOSE: To investigate the effect of tyrphostin 8 (T-8), a GTPase inhibitor, on transferrin receptor (TfR)-mediated transcytosis of insulin-transferrin (In-Tf) conjugate in cultured enterocyte-like Caco-2 cells and on gastrointestinal (GI) absorption of In-Tf in streptozotocin (STZ)-induced diabeticrats. METHODS: Caco-2 cells and diabeticrats were used as in vitro and in vivo models, respectively. TfR-mediated transcytosis was measured using 125I-In-Tf. The absorption of insulin in diabeticrats was demonstrated by the hypoglycemic effect. Rat blood glucose level was determined using a ONE TOUCH blood glucose monitoring system. RESULTS:T-8 increased apical-to-basolateral transport of In-Tf conjugate by enhancing TfR-mediated transcytosis in filter-grown Caco-2 cell monolayer, and this enhancement was higher and faster than the previously reported brefeldin A (BFA)-induced effect. The measurement of transepithelial electrical resistance (TEER) during the transport study showed that T-8 was less destructive on the cell tight junction than BFA. The GI absorption of In-Tf was evaluated by its hypoglycemic effect after oral administration in STZ-induced diabeticrats. The glucose-lowering effect of orally administered In-Tf in STZ-induced diabeticrats was improved by either T-8 or BFA. However, the effect of T-8 was more potent than that of BFA, especially at 7 h after administration. Either non-conjugated insulin or insulin-human serum albumin (In-HSA) conjugate by itself or in combination with T-8 did not show any hypoglycemic effect after oral administration, indicating that T-8-enhanced hypoglycemic activity of In-Tf was due to a selective enhancement of TfR-mediated transcytosis. CONCLUSIONS: Our data indicated that T-8 could be used to increase the GI absorption of insulin as a transferrin conjugate. T-8, as an enhancer of TfR-mediated transcytosis, is better than the previously reported BFA. T-8 produces a higher increase on the transport of In-Tf and a lower toxicity on epithelial cells. Our findings provide an alternative approach to promote the GI absorption of insulin, as well as other peptide or protein drugs.
Authors: R A Jackson; J B Hamling; P M Blix; B M Sim; M I Hawa; J B Jaspan; J Belin; J D Nabarro Journal: J Clin Endocrinol Metab Date: 1986-09 Impact factor: 5.958
Authors: J Abed; C Lebreton; G Champier; A Cuvillier; M Cogné; B Meresse; C Dugave; M Garfa-Traoré; B Corthésy; N Cerf-Bensussan; M Heyman Journal: Mucosal Immunol Date: 2013-07-10 Impact factor: 7.313
Authors: Corine C Visser; L Heleen Voorwinden; Daan J A Crommelin; Meindert Danhof; Albertus G de Boer Journal: Pharm Res Date: 2004-05 Impact factor: 4.200
Authors: Satoshi Inoue; Rameshwar Patil; Jose Portilla-Arias; Hui Ding; Bindu Konda; Andres Espinoza; Dmitriy Mongayt; Janet L Markman; Adam Elramsisy; H Westley Phillips; Keith L Black; Eggehard Holler; Julia Y Ljubimova Journal: PLoS One Date: 2012-02-15 Impact factor: 3.240