Single-injection ornithine decarboxylase-directed antisense therapy using atelocollagen to suppress human cancer growth

Atelocollagen-mediated in vivo siRNA transfection in ovarian carcinoma is influenced by tumor site, siRNA target and administration route

Ovarian cancer is the leading cause of death from gynecological malignancies worldwide, and innate or acquired chemoresistance of ovarian cancer cells is the major cause of therapeutic failure. It has been demonstrated that the concomitant inhibition of Bcl-xL and Mcl-1 anti-apoptotic activities is able to trigger apoptosis in chemoresistant ovarian cancer cells. In this context, siRNA-mediated Bcl‑xL and Mcl-1 inhibition constitutes an appealing strategy by which to eliminate chemoresistant cancer cells. However, the safest and most efficient way to vectorize siRNAs in vivo is still under debate. In the present study, using in vivo bioluminescence imaging, we evaluated the interest of atelocollagen to vectorize siRNAs by intraperitoneal (i.p.) or intravenous (i.v.) administration in 2 xenografted ovarian cancer models (peritoneal carcinomatosis and subcutaneous tumors in nude mice). Whereas i.p. administration of atelocollagen-vectorized siRNA in the peritoneal carcinomatosis model did not induce any gene downregulation, a 70% transient downregulation of luciferase expression was achieved after i.v. injection of atelocollagen-vectorized siRNA in the subcutaneous (s.c.) model. However, the use of siRNA targeting Bcl-xL or Mcl-1 did not induce target-specific downregulation in vivo in nude mice. Our results therefore show that atelocollagen complex formulation, the administration route, tumor site and the identity of the siRNA target influence the efficiency of atelocollagen‑mediated siRNA delivery.

Silencing Myostatin Using Cholesterol-conjugated siRNAs Induces Muscle Growth

Short interfering RNAs (siRNAs) are a valuable tool for gene silencing with applications in both target validation and therapeutics. Many advances have recently been made to improve potency and specificity, and reduce toxicity and immunostimulation. However, siRNA delivery to a variety of tissues remains an obstacle for this technology. To date, siRNA delivery to muscle has only been achieved by local administration or by methods with limited potential use in the clinic. We report systemic delivery of a highly chemically modified cholesterol-conjugated siRNA targeting muscle-specific gene myostatin (Mstn) to a full range of muscles in mice. Following a single intravenous injection, we observe 85–95% knockdown of Mstn mRNA in skeletal muscle and >65% reduction in circulating Mstn protein sustained for >21 days. This level of Mstn knockdown is also accompanied by a functional effect on skeletal muscle, with animals showing an increase in muscle mass, size, and strength. The cholesterol-conjugated siRNA platform described here could have major implications for treatment of a variety of muscle disorders, including muscular atrophic diseases, muscular dystrophy, and type II diabetes.

Influence of systemic administration of atelocollagen on mouse livers: an ideal biomaterial for systemic drug delivery

Atelocollagen (AC), a biomaterial with low antigenicity and high bioaffinity, has been widely used in implantable materials in clinical practice. Preclinical studies have demonstrated that AC is a potential drug carrier for local and systemic delivery of cytokines, growth factors, plasmid DNA, small interfering RNA, and microRNA. AC is also believed to have low systemic toxicity on the basis of the safety of implant usage; however, this is not enough determined. Therefore, we performed whole genome expression profiling in mouse liver after systemic administration of AC or the cationic liposome carrier DOTAP/cholesterol (LP) and compared the changes of gene expressions associated with hepatotoxicity. Microarray analysis revealed that systemic LP administration significantly increased expression of toxicity-related genes, i.e., those for lipocalin-2, cyclin-dependent kinase inhibitor 1A, serum amyloid A isoforms, chemokine ligands, and granzyme B. Alternatively, AC administration did not alter the expression of any of these genes. Further gene ontology (GO) enrichment analysis highlighted the characteristic annotations extracted from genes upregulated after LP administration, and most of them were related to toxicity annotations such as immune response, inflammatory response, and apoptosis induction. In contrast, GO enrichment analysis of genes induced after AC administration revealed that only three annotations, all of which were unrelated to toxicity. These findings indicate that AC is potentially far less hepatotoxic than LP after systemic administration, suggesting that AC may be an excellent biomaterial for nontoxic drug delivery system carriers.

Effects of atelocollagen formulation containing oligonucleotide on endothelial permeability

Atelocollagen is a major animal protein that is used as a highly biocompatible biomaterial. To date, atelocollagen has been used as an effective drug delivery technology to sustain the release of antitumor proteins and to enhance the antitumor activity of oligonucleotides in in vivo models. However, the biological effects of this technology are not fully understood. In the present study, we investigated the effects of atelocollagen on endothelial paracellular barrier function. An atelocollagen formulation containing oligonucleotides specifically increased the permeability of two types of endothelial cells, and the change was dependent on the molecular size, structure of the oligonucleotides used and the concentrations of the oligonucleotide and atelocollagen in the formulation. An immunohistochemical examination revealed that the formulation had effects on the cellular skeleton and intercellular structure although it did not affect the expression of adherens junction or tight junction proteins. These changes were induced through p38 MAP kinase signaling. It is important to elucidate the biological functions of atelocollagen in order to be able to exploit its drug delivery properties.

Circadian variations in rat liver gene expression: relationships to drug actions

Chronopharmacology is an important but under-explored aspect of therapeutics. Rhythmic variations in biological processes can influence drug action, including pharmacodynamic responses, due to circadian variations in the availability or functioning of drug targets. We hypothesized that global gene expression analysis can be useful in the identification of circadian-regulated genes involved in drug action. Circadian variations in gene expression in rat liver were explored using Affymetrix gene arrays. A rich time series involving animals analyzed at 18 time points within the 24-h cycle was generated. Of the more than 15,000 probe sets on these arrays, 265 exhibited oscillations with a 24-h frequency. Cluster analysis yielded five distinct circadian clusters, with approximately two thirds of the transcripts reaching maximal expression during the dark/active period of the animal. Of the 265 probe sets, 107 were identified as having potential therapeutic importance. The expression levels of clock genes were also investigated in this study. Five clock genes exhibited circadian variation in the liver, and data suggest that these genes may also be regulated by corticosteroids.