A Zhirnov1, E Nam2, G Badun1, A Romanyuk3, A Ezhov4, N Melik-Nubarov1, I Grozdova5. 1. Department of Chemistry, Lomonosov Moscow State University, GSP-1, Leninskie gory 1, build. 3, Moscow, 119991, Russia. 2. Australian Institute for Bioengineering and Nanotechnology (AIBN), University of Queensland, Corner College and Cooper Rds. (Bldg. 75), Brisbane, QLD, 4072, Australia. 3. Department of Chemistry, Aarhus University, 8000, Langelandsgade, 140, Aarhus, Denmark. 4. Faculty of Physics, Lomonosov Moscow State University, GSP-1, Leninskie gory 1, build. 2, Moscow, 119991, Russia. 5. Department of Chemistry, Lomonosov Moscow State University, GSP-1, Leninskie gory 1, build. 3, Moscow, 119991, Russia. grozdova@genebee.msu.ru.
Abstract
PURPOSE: Pluronics are known as inhibitors of multidrug resistance thus making tumor cells sensitive to therapeutic doses of drugs. The purpose of our study consists in revealing molecular targets of the hydrophobic poly(propylene oxide) block of pluronics in living cells and the dependence of the polymers chemosensitizing efficiency upon targeting. METHODS: A photo sensitive tracer was attached to the hydrophobic poly(propylene oxide) block of 3H-labeled tert-Bu-EO-PO copolymer. The conjugate was used for treatment cells in culture. We searched for its complexes with cellular lipids or proteins using RP TLC and SDS-electrophoresis, respectively. The chemosensitizing efficiency of pluronics was evaluated by their least concentrations sufficient for MDR reversion (CMDR). RESULTS: The poly(propylene oxide) block inserts in the lipid core of plasma membrane. No preferential binding of the conjugate with any cellular protein, particularly P-gp, has been detected. FITC-labeled pluronic L61 bound to alcohol insoluble cellular targets did not participate in MDR reversion. CMDR values of 13 block copolymers have been determined. These values inversely correlated with the polymers affinity toward lipids and the ability to accelerate flip-flop. CONCLUSION: Insertion of the hydrophobic poly(propylene oxide) block of amphiphiles in the lipid core of plasma membrane and acceleration of flip-flop of lipids underlie the mechanism of MDR reversion.
PURPOSE: Pluronics are known as inhibitors of multidrug resistance thus making tumor cells sensitive to therapeutic doses of drugs. The purpose of our study consists in revealing molecular targets of the hydrophobic poly(propylene oxide) block of pluronics in living cells and the dependence of the polymers chemosensitizing efficiency upon targeting. METHODS: A photo sensitive tracer was attached to the hydrophobic poly(propylene oxide) block of 3H-labeled tert-Bu-EO-PO copolymer. The conjugate was used for treatment cells in culture. We searched for its complexes with cellular lipids or proteins using RP TLC and SDS-electrophoresis, respectively. The chemosensitizing efficiency of pluronics was evaluated by their least concentrations sufficient for MDR reversion (CMDR). RESULTS: The poly(propylene oxide) block inserts in the lipid core of plasma membrane. No preferential binding of the conjugate with any cellular protein, particularly P-gp, has been detected. FITC-labeled pluronic L61 bound to alcohol insoluble cellular targets did not participate in MDR reversion. CMDR values of 13 block copolymers have been determined. These values inversely correlated with the polymers affinity toward lipids and the ability to accelerate flip-flop. CONCLUSION: Insertion of the hydrophobic poly(propylene oxide) block of amphiphiles in the lipid core of plasma membrane and acceleration of flip-flop of lipids underlie the mechanism of MDR reversion.
Authors: Daria Yu Alakhova; Nataliya Y Rapoport; Elena V Batrakova; Alexander A Timoshin; Shu Li; David Nicholls; Valery Yu Alakhov; Alexander V Kabanov Journal: J Control Release Date: 2009-10-06 Impact factor: 9.776