Figure 3

The cytotoxicity of MDR-1 siRNA-Dox-SiO₂ nanoparticles against MCF-7/MDR cells. (A) (a) P-gp expression determined through Western blot in treatment of various MDR-1 siRNAs transfected by Lipofectamiane^TM2000 in MCF-7/MDR cells. WT, without treatment; L-NC, Lipofectamiane^TM2000-NC siRNA; L-S1, Lipofectamiane^TM2000-MDR-1 siRNA-1; L-S2, Lipofectamiane^TM 2000-MDR-1 siRNA-2; L-S3, Lipofectamiane^TM2000-MDR-1 siRNA-3; L-S4, Lipofectamiane^TM2000-MDR-1 siRNA-4. (b) P-gp expression measured by Western blot in treatment of various silica-based siRNA formulations in MCF-7/MDR cells. WT, without treatment; 1, NC siRNA-Dox-SiO₂; 2, MDR-1 siRNA-Dox-SiO₂; 3, MDR-1 siRNA-SiO₂. (B) Cytotoxicity of MDR-1 siRNA-Dox-SiO₂ (MDR siRNA refer to MDR siRNA-3) containing different Dox concentrations determined by CCK-8 assay in MCF-7/MDR cells. MDR-1 siRNA-Dox-SiO₂-1, Dox concentration at 500 ng/mL; MDR-1 siRNA-Dox-SiO₂-2, Dox concentration at 1000 ng/mL; MDR-1 siRNA-Dox-SiO₂-3, Dox concentration at 2000 ng/mL. Free Dox group with concentration of 2000 ng/mL. All of groups contained the same siRNA value. *p<0.01; **p<0.001;***p<0.0001, n=5. (C) The cellular Dox retention observed by CLSM (confocal laser scanning microscopy) 60 hrs after treating with Dox (a), NC siRNA-Dox-SiO₂ (b) and MDR-1 siRNA-Dox-SiO₂ (c). (d) The cellular Dox retention determined by FCM (flow cytometry) 60 hrs after treating with Dox (green line), NC siRNA-Dox-SiO₂ (blue line) and MDR-1 siRNA-Dox-SiO₂ (red line); the black line denoted as the control group (without any nanocarrier and Dox). Bar=50 μm.

Abbreviations: NC siRNA, negative small interfering RNA; Dox, doxorubicin; SiO₂, silica.