A novel targeted drug delivery system, glucose-conjugated chitosan nanoparticles （GCNPs）, was developed for specific recognition and interaction with glucose transporters （Gluts） over-expressed by tumor cells. GC ...A novel targeted drug delivery system, glucose-conjugated chitosan nanoparticles （GCNPs）, was developed for specific recognition and interaction with glucose transporters （Gluts） over-expressed by tumor cells. GC was synthesized by using succinic acid as a linker between glucosamine and chitosan （CS）, and successful synthesis was confirmed by NMR and elemental analysis. GCNPs were prepared by ionic crosslinking method, and characterized in terms of morphology, size, and zeta potential. The optimally prepared nanoparticles showed spherical shapes with an average particle size of （187.9 ± 3.8） nm and a zeta potential of （-15.43 ± 0.31） mV. The GCNPs showed negligible cytotoxicity to mouse embryo fibroblast and 4T1 cells. Doxorubicin （DOX） could be efficiently entrapped into GCNPs, with a loading capacity and encapsulation efficiency of 20.11% and 64.81%, respectively. DOX-Ioaded nanoparticles exhibited sustained-release behavior in phosphate buffered saline （pH 7.4）. In vitro cellular uptake studies showed that the GCNPs had better endocytosis ability than CSNPs, and the antitumor activity of DOX/GCNPs was 4-5 times effectiveness in 4T1 cell killing than that of DOX/CSNPs. All the results demonstrate that nanoparticles decorated with glucose have specific interactions with cancer cells via the recognition between glucose and Gluts. Therefore, Gluts-targeted GCNPs may be promising delivery agents in cancer therapies.展开更多
L6 skeletal muscle myoblasts stably overexpressing glucose transporter GLUT1 or GLUT4 with exofa- cial myc-epitope tags were characterized for their response to insulin. In clonally selected cultures, 2-deoxyglucose u...L6 skeletal muscle myoblasts stably overexpressing glucose transporter GLUT1 or GLUT4 with exofa- cial myc-epitope tags were characterized for their response to insulin. In clonally selected cultures, 2-deoxyglucose uptake into L6-GLUT1myc myoblasts and myotubes was linear within the time of study. In L6-GLUT1myc and L6-GLUT4myc myoblasts, 100 nmol/L insulin treatment increased the GLUT1 content of the plasma membrane by 1.58±0.01 fold and the GLUT4 content 1.96±0.11 fold, as well as the 2-deoxyglucose uptake 1.53±0.09 and 1.86±0.17 fold respectively, all by a wortmannin-inhibitable manner. The phosphorylation of Akt in these two cell lines was increased by insulin. L6-GLUT1myc myoblasts showed a dose-dependent stimulation of glucose uptake by insulin, with unaltered sensitiv- ity and maximal responsiveness compared with wild type cells. By contrast, the improved insulin re- sponsiveness and sensitivity of glucose uptake were observed in L6-GLUT4myc myoblasts. Earlier studies indicated that forskolin might affect insulin-stimulated GLUT4 translocation. A 65% decrease of insulin-stimulated 2-deoxyglucose uptake in GLUT4myc cells was not due to an effect on GLUT4 mobi- lization to the plasma membrane, but instead on direct inhibition of GLUT4. Forskolin and dipyridamole are more potent inhibitors of GLUT4 than GLUT1. Alternatively, pentobarbital inhibits GLUT1 more than GLUT4. The use of these inhibitors confirmed that the overexpressed GLUT1 or GLUT4 are the major functional glucose transporters in unstimulated and insulin-stimulated L6 myoblasts. Therefore, L6-GLUT1myc and L6-GLUT4myc cells provide a platform to screen compounds that may have differ- ential effects on GLUT isoform activity or may influence GLUT isoform mobilization to the cell surface of muscle cells.展开更多
基金This research was supported by the National Natural Science Foundation of China （Grant Nos. 31000423 and 31301420） and the China Postdoctoral Science Foundation （Grant No. 2014M551965）.
文摘A novel targeted drug delivery system, glucose-conjugated chitosan nanoparticles （GCNPs）, was developed for specific recognition and interaction with glucose transporters （Gluts） over-expressed by tumor cells. GC was synthesized by using succinic acid as a linker between glucosamine and chitosan （CS）, and successful synthesis was confirmed by NMR and elemental analysis. GCNPs were prepared by ionic crosslinking method, and characterized in terms of morphology, size, and zeta potential. The optimally prepared nanoparticles showed spherical shapes with an average particle size of （187.9 ± 3.8） nm and a zeta potential of （-15.43 ± 0.31） mV. The GCNPs showed negligible cytotoxicity to mouse embryo fibroblast and 4T1 cells. Doxorubicin （DOX） could be efficiently entrapped into GCNPs, with a loading capacity and encapsulation efficiency of 20.11% and 64.81%, respectively. DOX-Ioaded nanoparticles exhibited sustained-release behavior in phosphate buffered saline （pH 7.4）. In vitro cellular uptake studies showed that the GCNPs had better endocytosis ability than CSNPs, and the antitumor activity of DOX/GCNPs was 4-5 times effectiveness in 4T1 cell killing than that of DOX/CSNPs. All the results demonstrate that nanoparticles decorated with glucose have specific interactions with cancer cells via the recognition between glucose and Gluts. Therefore, Gluts-targeted GCNPs may be promising delivery agents in cancer therapies.
基金Supported by the National Natural Science Foundation of China (Grant No. 30570912)the National Natural Science Foundation of China (China-Canada Joint Health Research) (Grant No. 30611120532)+1 种基金the Tianjin Municipal Science and Technology Commission, China (Grant Nos. 07JCZDJC07900 and 06YFGPSH03300)the Foundation of Tianjin Education Bureau, China (Grant No. 20040106)
文摘L6 skeletal muscle myoblasts stably overexpressing glucose transporter GLUT1 or GLUT4 with exofa- cial myc-epitope tags were characterized for their response to insulin. In clonally selected cultures, 2-deoxyglucose uptake into L6-GLUT1myc myoblasts and myotubes was linear within the time of study. In L6-GLUT1myc and L6-GLUT4myc myoblasts, 100 nmol/L insulin treatment increased the GLUT1 content of the plasma membrane by 1.58±0.01 fold and the GLUT4 content 1.96±0.11 fold, as well as the 2-deoxyglucose uptake 1.53±0.09 and 1.86±0.17 fold respectively, all by a wortmannin-inhibitable manner. The phosphorylation of Akt in these two cell lines was increased by insulin. L6-GLUT1myc myoblasts showed a dose-dependent stimulation of glucose uptake by insulin, with unaltered sensitiv- ity and maximal responsiveness compared with wild type cells. By contrast, the improved insulin re- sponsiveness and sensitivity of glucose uptake were observed in L6-GLUT4myc myoblasts. Earlier studies indicated that forskolin might affect insulin-stimulated GLUT4 translocation. A 65% decrease of insulin-stimulated 2-deoxyglucose uptake in GLUT4myc cells was not due to an effect on GLUT4 mobi- lization to the plasma membrane, but instead on direct inhibition of GLUT4. Forskolin and dipyridamole are more potent inhibitors of GLUT4 than GLUT1. Alternatively, pentobarbital inhibits GLUT1 more than GLUT4. The use of these inhibitors confirmed that the overexpressed GLUT1 or GLUT4 are the major functional glucose transporters in unstimulated and insulin-stimulated L6 myoblasts. Therefore, L6-GLUT1myc and L6-GLUT4myc cells provide a platform to screen compounds that may have differ- ential effects on GLUT isoform activity or may influence GLUT isoform mobilization to the cell surface of muscle cells.
