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.

Understanding the mechanism of radioresistance could help develop strategies to improve therapeutic response of patients with PDAC. The gene is frequently mutated in pancreatic cancer. In this study, we investigated the role of deficiency in pancreatic cancer cells' response to radiotherapy. We downregulated SMAD4 expression with siRNA or shRNA and overexpressed SMAD4 in mutant pancreatic cancer cells followed by clonogenic survival assay to evaluate their effects on cell radioresistance. To study the mechanism of radioresistance, the effects of loss on reactive oxygen species (ROS) and autophagy were determined by flow cytometry and immunoblot analysis, respectively. Furthermore, we measured radioresistance by clonogenic survival assay after treatment with autophagy inhibitor (Chloroquine) and ROS inhibitor (N-acetyl-l-cysteine) in -depleted pancreatic cancer cells. Finally, the effects of on radioresistance were also confirmed in an orthotopic tumor model derived from -depleted Panc-1 cells.-depleted pancreatic cancer cells were more resistant to radiotherapy based on clonogenic survival assay. Overexpression of wild-type SMAD4 in -mutant cells rescued their radiosensitivity. Radioresistance mediated by depletion was associated with persistently higher levels of ROS and radiation-induced autophagy. Finally, depletion induced radioresistance in Panc-1-derived orthotopic tumor model ( = 0.038). More interestingly, we observed that the protein level of SMAD4 is inversely correlated with autophagy in orthotopic tumor tissue samples. Our results demonstrate that defective is responsible for radioresistance in pancreatic cancer through induction of ROS and increased level of radiation-induced autophagy..

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.

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.

Drug to carrier ratio is an important consideration in designing drug platforms, since a low loading capacity necessitates the use of high doses of carriers, which can result in side effects. Here, we have engineered a platform to co-deliver small molecule drugs and small interfering RNA (siRNA). This platform consists of cyclodextrin-grafted polyethylenimine (CP) functionalized mesoporous silica nanoparticles (MSNP). A unique multi-step encapsulation procedure was used to obtain a high loading capacity for doxorubicin (DOX) and siRNA oligos specific for the PKM2 gene that encodes pyruvate kinase M2, an enzyme catalyzing the final rate-limiting step in glycolysis. We systematically characterized this platform (CP-MSNP@DOX/PKM2) in vitro and evaluated its therapeutic efficacy in vivo with a mouse model of triple negative breast cancer (TNBC). Exposure of TNBC cells to CP-MSNP@DOX/PKM2 resulted in suppressed target gene expression, reduced cell proliferation, and enhanced apoptosis. Intravenous administration of the drug substantially decreased the tumor burden in comparison to DOX or siRNA monotherapy. In conclusion, we have developed a platform for efficient co-delivery of small molecule drugs and therapeutic siRNA.

Colorectal cancer is the third leading cause of cancer-related mortality in the world; death usually results from uncontrolled metastatic disease. Previously, we developed a novel strategy of TNF-related apoptosis-inducing ligand (Apo2L/TRAIL) in combination with hyperthermia to treat hepatic colorectal metastases. However, previous studies suggest a potential hepatocyte cytotoxicity with TRAIL. Unlike TRAIL, anti-human TRAIL receptor antibody induces apoptosis without hepatocyte toxicity. In this study, we evaluated the anti-tumor efficacy of humanized anti-death receptor 4 (DR4) antibody mapatumumab (Mapa) by comparing it with TRAIL in combination with hyperthermia. TRAIL, which binds to both DR4 and death receptor 5 (DR5), was approximately 10-fold more effective than Mapa in inducing apoptosis. However, hyperthermia enhances apoptosis induced by either agent. We observed that the synergistic effect was mediated through elevation of reactive oxygen species, c-Jun N-terminal kinase activation, Bax oligomerization and translocalization to the mitochondria, loss of mitochondrial membrane potential, release of cytochrome c to cytosol, activation of caspases and increase in poly(ADP-ribose) polymerase cleavage. We believe that the successful outcome of this study will support the application of Mapa in combination with hyperthermia to colorectal hepatic metastases.