Tumor Microenvironment-Responsive Multistaged Nanoplatform for Systemic RNAi and Cancer Therapy.

While RNA interference (RNAi) therapy has demonstrated significant potential for cancer treatment, the effective and safe systemic delivery of RNAi agents such as small interfering RNA (siRNA) into tumor cells in vivo remains challenging. We herein reported a unique multistaged siRNA delivery nanoparticle (NP) platform, which is comprised of (i) a polyethylene glycol (PEG) surface shell, (ii) a sharp tumor microenvironment (TME) pH-responsive polymer that forms the NP core, and (iii) charge-mediated complexes of siRNA and tumor cell-targeting- and penetrating-peptide-amphiphile (TCPA) that are encapsulated in the NP core. When the rationally designed, long circulating polymeric NPs accumulate in tumor tissues after intravenous administration, the targeted siRNA-TCPA complexes can be rapidly released via TME pH-mediated NP disassembly for subsequent specific targeting of tumor cells and cytosolic transport, thus achieving efficient gene silencing. In vivo results further demonstrate that the multistaged NP delivery of siRNA against bromodomain 4 (BRD4), a recently discovered target protein that regulates the development and progression of prostate cancer (PCa), can significantly inhibit PCa tumor growth.

Synthesis and characterization of asymmetrical gemini surfactants.

The effect of variation in the length of surfactant hydrocarbon tail groups was tested in a series of dissymmetric gemini surfactants (N1-alkyl N1,N1,N3,N3-tetramethyl-N3-(6-pyren-6yl)-hexyl)propane-1,3-diammonium dibromide designated as CmC3CnBr, with m = hexyl pyrene, and n = 8, 12, 14, 16, and 18. The aggregation properties of these surfactants have been investigated by means of 1H NMR, fluorescence spectroscopy, surface tension and electrical conductivity measurements. The critical micelle concentration (CMC) was determined using surface tension and confirmed using the specific conductance method. Krafft temperatures and the degree of micelle ionization (α) were obtained from specific conductance measurements. With an increase of the dissymmetry (m/n) ratio, the CMC decreased linearly and an increase in the Krafft temperatures was observed for all of the gemini surfactants. α values for the dissymmetric GS were higher than those of the m-3-m counterparts, which may be attributed to enhanced micelle-micelle interactions that arise from increased hydrophobicity of the hydrocarbon chains. The introduction of the bulky pyrenyl tail group resulted in much lower CMC values compared to their symmetrical counterparts affecting the packing of these surfactants at the air/water interface, which resulted in high-ordered structures (lamellar and inverted micelles). This in turn affected the thermodynamic parameters of the micellization.

ROS-Responsive Polyprodrug Nanoparticles for Triggered Drug Delivery and Effective Cancer Therapy.

The application of nanoparticles (NPs) to drug delivery has led to the development of novel nanotherapeutics for the treatment of various diseases including cancer. However, clinical use of NP-mediated drug delivery has not always translated into improved survival of cancer patients, in part due to the suboptimal properties of NP platforms, such as premature drug leakage during preparation, storage, or blood circulation, lack of active targeting to tumor tissue and cells, and poor tissue penetration. Herein, an innovative reactive oxygen species (ROS)-responsive polyprodrug is reported that can self-assemble into stable NPs with high drug loading. This new NP platform is composed of the following key components: (i) polyprodrug inner core that can respond to ROS for triggered release of intact therapeutic molecules, (ii) polyethylene glycol (PEG) outer shell to prolong blood circulation; and (iii) surface-encoded internalizing RGD (iRGD) to enhance tumor targeting and tissue penetration. These targeted ROS-responsive polyprodrug NPs show significant inhibition of tumor cell growth both in vitro and in vivo.

Multifunctional Envelope-Type siRNA Delivery Nanoparticle Platform for Prostate Cancer Therapy.

With the capability of specific silencing of target gene expression, RNA interference (RNAi) technology is emerging as a promising therapeutic modality for the treatment of cancer and other diseases. One key challenge for the clinical applications of RNAi is the safe and effective delivery of RNAi agents such as small interfering RNA (siRNA) to a particular nonliver diseased tissue (e.g., tumor) and cell type with sufficient cytosolic transport. In this work, we proposed a multifunctional envelope-type nanoparticle (NP) platform for prostate cancer (PCa)-specific in vivo siRNA delivery. A library of oligoarginine-functionalized and sharp pH-responsive polymers was synthesized and used for self-assembly with siRNA into NPs with the features of long blood circulation and pH-triggered oligoarginine-mediated endosomal membrane penetration. By further modification with ACUPA, a small molecular ligand specifically recognizing prostate-specific membrane antigen (PSMA) receptor, this envelope-type nanoplatform with multifunctional properties can efficiently target PSMA-expressing PCa cells and silence target gene expression. Systemic delivery of the siRNA NPs can efficiently silence the expression of prohibitin 1 (PHB1), which is upregulated in PCa and other cancers, and significantly inhibit PCa tumor growth. These results suggest that this multifunctional envelope-type nanoplatform could become an effective tool for PCa-specific therapy.