Abstract
Background
One of the major obstacles in the treatment of breast cancer is breast cancer stem cells (BCSC) which are resistant to standard chemotherapeutic drugs. It has been proven that microRNA-200c (miR-200c) can restore sensitivity to microtubule-targeting chemotherapeutic drugs by reducing the expression of class III β-tubulin. In this study, combination therapy with miR-200c and paclitaxel (PTX) mediated by lipid nanoparticles was investigated as an alternative strategy against BCSC.
Materials and methods
A cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane was strategically selected to formulate solid lipid nanoparticles (SLN) for miR-200c delivery. Nanostructured lipid carriers (NLC) with 20 wt% oleic acid were prepared for PTX delivery. Mammospheres, which gained the characteristics of BCSC, were used as a cell model to evaluate the efficiency of combination therapy.
Results
The cationic SLN could condense anionic miRNA to form SLN/miRNA complexes via charge interactions and could protect miRNA from degradation by ribonuclease. SLN/miR-200c complexes achieved 11.6-fold expression of miR-200c after incubation for 24 hours, compared with that of Lipofectamine™ 2000/miR-200c complexes (*P<0.05). Intracellular drug release assay proved that miRNA can be released from SLN/miRNA complexes efficiently in 12 hours after cellular uptake. After BCSC were transfected with SLN/miR-200c, the expression of class III β-tubulin was effectively downregulated and the cellular cytotoxicity of PTX-loaded NLC (NLC/PTX) against BCSC was enhanced significantly (**P<0.01).
Conclusion
The results indicated that the cationic SLN could serve as a promising carrier for miRNA delivery. In addition, the combination therapy of miR-200c and PTX revealed a novel therapeutic strategy for the treatment of BCSC.
Acknowledgments
The authors thank the National Natural Science Foundation of China (NSFC No 81273442 81473144) and the Zhejiang Provincial Program for the Cultivation of High-level Innovative Health Talents for their financial support.
Disclosure
The authors report no conflicts of interest in this work.