It was reported previously that tamoxifen (TAM) could increase the intracellular accumulation of drug-loaded liposomes, but the exact mechanism is unknown although it was supposed that TAM might enhance the cell upt...It was reported previously that tamoxifen (TAM) could increase the intracellular accumulation of drug-loaded liposomes, but the exact mechanism is unknown although it was supposed that TAM might enhance the cell uptake by inhibiting the drug efflux caused by P-glycoprotein (P-gp). To identify the mechanism of increased cellular uptake of liposomes induced by tamoxifen, PEGgylated liposomes (SSL) ofP-gp-substrate doxorubicin (DOX) or non-P-gp-substrate coumarin (Cou) were prepared with or without TAM. The cell uptake of these liposome systems was investigated in cell lines with different P-gp-expressing levels and the interaction of TAM with lipid membrane was also studied. As the results, the co-encapsulation of TAM with DOX-SSL increased the intracellular uptake in all three tumor cell lines. In P-gp-highly-expressing MCF-7/Adr cells, the effect of TAM was the strongest and in negative control Hela cells, the impact weakened but still significant. The improvement was also observed in the cellular uptake of Cou-SSL. Surface plasmon resonance (SPR) studies demonstrated that TAM-SSL exhibited a much stronger atYmity with model biomembrane compared with empty SSL, and ft^her test with isothermal titration calorimetry (ITC) showed that free TAM had an obvious interaction with lipid membrane. In conclusion, TAM could increase the affinity of liposomes with biomembrane and enhance the intracellular accumulation of liposomes via both TAM-mediated P-gp inhibition and the increased interaction between hydrophobic TAM molecules and lipid membrane.展开更多
Photoaffinity cross-linking is a fast developing technology for biomolecular interactions,including receptor-ligand binding.The chemical mechanisms of the most commonly used photoactivatable probes and their respectiv...Photoaffinity cross-linking is a fast developing technology for biomolecular interactions,including receptor-ligand binding.The chemical mechanisms of the most commonly used photoactivatable probes and their respective photochemistry are summarized.This review focuses on the expanding utilities of this technology as a result of recent advances in the(i)identification of receptor contact sites,(ii)monitoring ligand-induced receptor conformational changes,(iii)identification of global binding surfaces,(iv)binding mode analysis using bifunctional photo-probes,(v)application of biosynthetic photo-probes,and(vi)examples of novel target discovery using this technology.Limitations and future potential of this approach are also discussed.展开更多
基金National Natural Science Foundation of China(Grant No.81130059)
文摘It was reported previously that tamoxifen (TAM) could increase the intracellular accumulation of drug-loaded liposomes, but the exact mechanism is unknown although it was supposed that TAM might enhance the cell uptake by inhibiting the drug efflux caused by P-glycoprotein (P-gp). To identify the mechanism of increased cellular uptake of liposomes induced by tamoxifen, PEGgylated liposomes (SSL) ofP-gp-substrate doxorubicin (DOX) or non-P-gp-substrate coumarin (Cou) were prepared with or without TAM. The cell uptake of these liposome systems was investigated in cell lines with different P-gp-expressing levels and the interaction of TAM with lipid membrane was also studied. As the results, the co-encapsulation of TAM with DOX-SSL increased the intracellular uptake in all three tumor cell lines. In P-gp-highly-expressing MCF-7/Adr cells, the effect of TAM was the strongest and in negative control Hela cells, the impact weakened but still significant. The improvement was also observed in the cellular uptake of Cou-SSL. Surface plasmon resonance (SPR) studies demonstrated that TAM-SSL exhibited a much stronger atYmity with model biomembrane compared with empty SSL, and ft^her test with isothermal titration calorimetry (ITC) showed that free TAM had an obvious interaction with lipid membrane. In conclusion, TAM could increase the affinity of liposomes with biomembrane and enhance the intracellular accumulation of liposomes via both TAM-mediated P-gp inhibition and the increased interaction between hydrophobic TAM molecules and lipid membrane.
文摘Photoaffinity cross-linking is a fast developing technology for biomolecular interactions,including receptor-ligand binding.The chemical mechanisms of the most commonly used photoactivatable probes and their respective photochemistry are summarized.This review focuses on the expanding utilities of this technology as a result of recent advances in the(i)identification of receptor contact sites,(ii)monitoring ligand-induced receptor conformational changes,(iii)identification of global binding surfaces,(iv)binding mode analysis using bifunctional photo-probes,(v)application of biosynthetic photo-probes,and(vi)examples of novel target discovery using this technology.Limitations and future potential of this approach are also discussed.