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Purpose: To study tumor growth delay resulting from partial irradiation in preclinical mouse models. Methods and Materials: We investigated 67NR murine orthotopic breast tumors in both immunocompetent and nude mice. Treatment was delivered to 50% or 100% of the tumor using a 2×2 cm collimator on a micro-irradiator. Radiation response was modulated by treating with anti-CD8 and anti-ICAM antibodies. Similar experiments were performed using the less immunogenic Lewis Lung Carcinoma (LLC) mouse model. Tumor growth delay and gγH2AX phosphorylation were measured and immune response was assessed by immunofluorescence and flow cytometry at 1 and 7 days post-radiotherapy (RT). Tumor expression of cellular adhesion molecules was also measured at different times post-RT. Results: Partial irradiation led to tumor responses similar to fully exposed tumors in immunocompetent mice, but not in nude mice. After a single dose of 10Gy, infiltration of CD8 + T cells was observed, along with increased expression of ICAM. The response to 10Gy in hemi-*

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MicroRNAs (miRNAs) are small noncoding RNAs found to govern nearly every biological process. They frequently acquire a gain or a loss of function in cancer, hence playing a causative role in the development and progression of cancer. There are major obstacles on the way for the successful delivery of miRNA, which include low cellular uptake of the RNA and endosomal escape, immunogenicity, degradation in the bloodstream, and rapid renal clearance. The delivered miRNA needs to be successfully routed to the target organ, enter the cell and reach its intracellular target in an active form. Consequently, in order to exploit the promise of RNA interference, there is an urgent need for efficient methods to deliver miRNAs. These can be divided into three main categories: complexation, encapsulation, and conjugation. In this review, we will discuss the special considerations for miRNA delivery for cancer therapy, focusing on nonviral delivery systems: lipid, polymeric, and inorganic nanocarriers.

Introduction: The etiology of radiation-induced erectile dysfunction (ED) is complex and multifactorial, and it appears to be mainly atherogenic. Aim: To focus on vascular aspects of radiation-induced ED and to elucidate whether the protective effects of sildenafil are mediated by attenuation of oxidative stress and apoptosis in the endothelial cells. Methods: Bovine aortic endothelial cells (BAECs), with or without pretreatment of sildenafil (5 mM at 5 minutes before radiation), were used to test endothelial dysfunction in response to external beam radiation at 10e15 Gy. Generation of reactive oxygen species (ROS) was studied. Extracellular hydrogen peroxide (H 2 O 2) was measured using the Amplex Red assay and intracellular H 2 O 2 using a fluorescent sensor. In addition, ROS superoxide (O 2-) was measured using a O 2chemiluminescence enhancer. Both H 2 O 2 and O2-are known to reduce the bioavailability of nitric oxide, which is the most significant chemical mediator of penile erection. Generation of cellular peroxynitrite (ONOO À) was measured using a chemiluminescence assay with the PNCL probe. Subsequently, we measured the activation of acid sphingomyelinase (ASMase) enzyme by radioenzymatic assay using [ 14 C-methylcholine] sphingomyelin as substrate, and the generation of the proapoptotic C 16-ceramide was assessed using the diacylglycerol kinase assay. Endothelial cells apoptosis was measured as a readout of these cells' dysfunction. Main Outcome Measures: Single high-dose radiation therapy induced NADPH oxidases (NOXs) activation and ROS generation via the proapoptotic ASMase/ceramide pathway. The radio-protective effect of sildenafil on BAECs was due to inhibition of this pathway. Results: Here, we demonstrate for the first time that radiation activated NOXs and induced generation of ROS in BAECs. In addition, we showed that sildenafil significantly reduced radiation-induced O 2and as a result there was reduction in the generation of peroxynitrite in these cells. Subsequently, sildenafil protected the endothelial cells from radiation therapy-induced apoptosis. Strengths and Limitations: This is the first study demonstrating that single high-dose radiation therapy induced NOXs activation, resulting in the generation of O 2and peroxynitrite in endothelial cells. Sildenafil reduced ROS generation by inhibiting the ASMase/ceramide pathway. These studies should be followed in an animal model of ED. Conclusions: This study demonstrated that sildenafil protects BAECs from radiation-induced oxidative stress by reducing NOX-induced ROS generation, thus resulting in decreased endothelial dysfunction. Therefore, it

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