No abstract

Gene silencing agents such as small interfering RNA (siRNA) and microRNA offer the promise to modulate expression of almost every gene for the treatment of human diseases including cancer. However, lack of vehicles for effective systemic delivery to the disease organs has greatly limited their in vivo applications. In this study, we developed a high capacity polycation-functionalized nanoporous silicon (PCPS) platform comprised of nanoporous silicon microparticles functionalized with arginine-polyethyleneimine inside the nanopores for effective delivery of gene silencing agents. Incubation of MDA-MB-231 human breast cancer cells with PCPS loaded with STAT3 siRNA (PCPS/STAT3) or GRP78 siRNA (PCPS/GRP78) resulted in 91% and 83% reduction of STAT3 and GRP78 gene expression in vitro. Treatment of cells with a microRNA-18a mimic in PCPS (PCPS/miR-18) knocked down 90% expression of the microRNA-18a target gene ATM. Systemic delivery of PCPS/STAT3 siRNA in murine model of MDA-MB-231 breast cancer enriched particles in tumor tissues and reduced STAT3 expression in cancer cells, causing significant reduction of cancer stem cells in the residual tumor tissue. At the therapeutic dosage, PCPS/STAT3 siRNA did not trigger acute immune response in FVB mice, including changes in serum cytokines, chemokines and colony-stimulating factors. In addition, weekly dosing of PCPS/STAT3 siRNA for four weeks did not cause signs of sub-acute toxicity based on changes in body weight, hematology, blood chemistry, and major organ histology. Collectively, the results suggest that we have developed a safe vehicle for effective delivery of gene silencing agents.

Effective delivery holds the key to successful in vivo application of therapeutic small interfering RNA (siRNA). In this work, we have developed a universal siRNA carrier consisting of a mesoporous silica nanoparticle (MSNP) functionalized with cyclodextrin-grafted polyethylenimine (CP). CP provides positive charge for loading of siRNA through electrostatic interaction and enables effective endosomal escape of siRNA. Using intravital microscopy we were able to monitor tumor enrichment of CP-MSNP/siRNA particles in live mice bearing orthotopic MDA-MB-231 xenograft tumors. CP-MSNP delivery of siRNA targeting the M2 isoform of the glycolytic enzyme pyruvate kinase (PKM2) resulted in effective knockdown of gene expression in vitro and in vivo. Suppression of PKM2 led to inhibition of tumor cell growth, invasion, and migration.

E-selectin is a surface marker of endothelial cell (EC) inflammation, one of the hallmarks of atherogenesis. Thus, we tested the hypothesis that delivery of microRNA (miR)-146a and miR-181b with an E-selectin-targeting multistage vector (ESTA-MSV) to inflamed endothelium covering atherosclerotic plaques inhibits atherosclerosis. Cy5-conjugated miR-146a and miR-181b were packaged in polyethylene glycol-polyethyleneimine (PEG/PEI) nanoparticles and loaded into ESTA-MSV microparticles. Both miRs were downregulated in tumor necrosis factor (TNF)-α-treated ECs. Transfection of TNF-α-treated mouse aortas and cultured ECs with miRs was more efficient with ESTA-MSV than with the PEG/PEI. Likewise, miR-146a/-181b packaged in ESTA-MSV efficiently suppressed the chemokines, CCL2, CCL5, CCL8, and CXCL9, and monocyte adhesion to ECs. Complementary in vivo tests were conducted in male apolipoprotein E-deficient mice fed a Western diet and injected intravenously with the particles prepared as above biweekly for 12 weeks. Treatment with miRs packaged in ESTA-MSV but not in PEG/PEI reduced atherosclerotic plaque size. Concurrently, vascular inflammation markers, including macrophages in aortic root lesions and chemokine expression in aortic tissues were reduced while the vascular smooth muscle cells and collagen increased in plaques from ESTA-MSV/miRs-treated vs. vehicle-treated mice. Our data supported our hypothesis that ESTA-MSV microparticle-mediated delivery of miR-146a/-181b ameliorates endothelial inflammation and atherosclerosis.

No abstract

SUMMARY Micro- and nano-meter size particles have become popular candidates for cancer vaccine adjuvants. However the mechanism by which such particles enhance immune responses remains unclear. Here we report a porous silicon microparticle (PSM)-based cancer vaccine that greatly enhances cross-presentation and activates type I interferon response in dendritic cells. PSM-loaded antigen exhibited prolonged early endosome localization and enhanced cross-presentation through both proteasome- and lysosome-dependent pathways. Phagocytosis of PSM by dendritic cells induced type I interferon responses through a TRIF- and MAVS-dependent pathway. Dendritic cells primed with PSM-loaded HER2 antigen produced robust CD8 T cell-dependent anti-tumor immunity in mice bearing HER2-positive mammary gland tumors. Importantly, this vaccination activated tumor immune microenvironment with elevated levels of intra-tumor type I interferon and MHC-II expression, abundant CD11c+ dendritic cell infiltration, and tumor-specific cytotoxic T cell responses. These findings highlight the potential for PSM as an immune adjuvant to potentiate dendritic cell-based cancer immunotherapy.

Cancer is a complex disease that usually requires several treatment modalities. Here, we have designed a multifunctional nanotherapeutic system incorporating small interfering RNA (siRNA) and gold nanorods for photothermal therapy. Surface engineered gold nanorods with polyethylenimine were synthesized using a layer-by-layer assembly and siRNA was absorbed on the surface. The siRNA was efficiently delivered into breast cancer cells, resulting in subsequent gene silencing. Cells were then irradiated with near-infrared (NIR) light, causing heat-induced anticancer activity. The combination of gene silencing and photothermal therapy resulted in effective inhibition of cell proliferation.

Ruthenium coordination complexes have the potential to serve as novel theranostic agents for cancer. However, a major limitation in their clinical implementation is effective tumor accumulation. In this study, we have developed a liposome-based theranostic nanodelivery system for [Ru(phen)2dppz](ClO4)2 (Lipo-Ru). This ruthenium polypyridine complex emits a strong fluorescent signal when incorporated in the hydrophobic lipid bilayer of the delivery vehicle or in the DNA helix, enabling visualization of the therapeutic agent in tumor tissues. Incubation of MDA-MB-231 breast cancer cells with Lipo-Ru induced double-strand DNA breaks and triggered apoptosis. In a mouse model of triple-negative breast cancer, treatment with Lipo-Ru dramatically reduced tumor growth. Biodistribution studies of Lipo-Ru revealed that more than 20% of the injected dose accumulated in the tumor. These results suggest that Lipo-Ru could serve as a promising theranostic platform for cancer.