Liposomal siRNA nanocarriers for cancer therapy

Small interfering RNAs (siRNA) have recently emerged as a new class of therapeutics with a great potential to revolutionize the treatment of cancer and other diseases. A specifically designed siRNA binds and induces post-transcriptional silencing of target genes (mRNA). Clinical applications of siRNA-based therapeutics have been limited by their rapid degradation, poor cellular uptake, and rapid renal clearance following systemic administration. A variety of synthetic and natural nanoparticles composed of lipids, polymers, and metals have been developed for siRNA delivery, with different efficacy and safety profiles. Liposomal nanoparticles have proven effective in delivering siRNA into tumor tissues by improving stability and bioavailability. While providing high transfection efficiency and a capacity to form complexes with negatively charged siRNA, cationic lipids/liposomes are highly toxic. Negatively charged liposomes, on the other hand, are rapidly cleared from circulation. To overcome these problems we developed highly safe and effective neutral lipid-based nanoliposomes that provide robust gene silencing in tumors following systemic (intravenous) administration. This delivery system demonstrated remarkable antitumor efficacy in various orthotopic human cancer models in animals. Here, we briefly overview this and other lipid-based approaches with preclinical applications in different tumor models for cancer therapy and potential applications as siRNA-nanotherapeutics in human cancers.