InflammamiRs in focus: Delivery strategies and therapeutic approaches

microRNAs (miRNAs) are small non-protein-coding RNAs which are essential regulators of host genome expression at the post-transcriptional level. There is evidence of dysregulated miRNA expression patterns in a wide variety of diseases, such as autoimmune and inflammatory conditions. These miRNAs have been termed "inflammamiRs." When working with miRNAs, the method followed, the approach to treat or diagnosis, and the selected biological material are very crucial. Demonstration of the role of miRNAs in particular disease phenotypes facilitates their evaluation as potential and effective therapeutic tools. A growing number of reports suggest the significant utility of miRNAs and other small RNA drugs in clinical medicine. Most miRNAs seem promising therapeutic options, but some features associated with miRNA therapy like off-target effect, effective dosage, or differential delivery methods, mainly caused by the short target's sequence, make miRNA therapies challenging. In this review, we aim to discuss some of the inflammamiRs in diseases associated with inflammatory pathways and the challenge of identifying the most potent therapeutic candidates and provide a perspective on achieving safe and targeted delivery of miRNA therapeutics. We also discuss the status of inflammamiRs in clinical trials.

The Toughness-Enhanced Atelocollagen Double-Network Gel for Biomaterials

A tough gel composed of atelocollagen, which lacks an immunogenetic site, is a promising material for biomedical application. In this study, we created a composite hydrogel composed of atelocollagen gel cross-linked with glutaraldehyde (GA) and poly-(N,N-dimethylacrylamide) gel exhibiting biocompatibility based on the double-network (DN) gel principle. The tensile toughness of atelocollagen gel remained constant regardless of the amount of cross-linker (GA) used. In contrast, tensile tests of the DN gel indicated that mechanical properties, such as fracture stress and toughness, were significantly higher than those of the atelocollagen gel. Moreover, fibroblast cells adhered and spread on the gels, the Schiff bases of which were treated via reductive amination for detoxification from GA. These findings demonstrate the potential of the proposed gel materials as artificial alternative materials to soft tissues with sub-MPa fracture stress.

Synthesis, Characterization, and Potential Application of Cyclodextrin-Based Polyrotaxanes for Reinforced Atelocollagen Threads

Preparing strong and flexible atelocollagen-based materials for biomedical applications is still a challenging task. To address this challenge, this study describes the synthesis and characterization of water-soluble polyrotaxanes (PRs) with different coverage ratios and molecular weights of axle polymers, and their potential applications for PR-reinforced atelocollagen threads (PRATs). A novel method was established for the syntheses of PRs with relatively low coverage ratio at the sub-gram scale, in which the aldehyde groups were employed as crosslinking sites for preparing the PRATs via reductive amination. The aldehyde groups were successfully quantified by 1H nuclear magnetic resonance spectroscopy using 1,1-dimethylhydrazine as an aldehyde marker. Fourier-transform infrared and thermogravimetric analysis measurements supported the characterization of the PRs. Interestingly, tensile testing demonstrated that coverage ratio affected the mechanical properties of the PRATs more strongly than molecular weight. The insights obtained in this study would facilitate the development of soft materials based on atelocollagens and PRs.

Long Noncoding RNA HOTAIR Promotes Epithelial-Mesenchymal Transition and Is a Suitable Target to Inhibit Peritoneal Dissemination in Human Scirrhous Gastric Cancers

OBJECTIVES

Scirrhous gastric cancer, which accounts for approximately 10% of all gastric cancers, often disseminates to the peritoneum, leading to intractable cases with poor prognosis. There is an urgent need for new treatment approaches for this difficult cancer.

METHODS

We previously established an original cell line, HSC-60, from a scirrhous gastric cancer patient and isolated a peritoneal-metastatic cell line, 60As6, in nude mice following orthotopic inoculations. In the present study, we focused on the expression of long noncoding ribonucleic acid (RNA) (lncRNA) in the cell lines and investigated the mechanism on peritoneal dissemination.

RESULTS

We demonstrated that an lncRNA, HOX transcript antisense RNA (HOTAIR), is expressed significantly more highly in 60As6 than HSC-60 cells. Then, using both HOTAIR knockdown and overexpression experiments, we showed that high-level expression of HOTAIR promotes epithelial-mesenchymal transition (EMT) in 60As6 cells. By luciferase assay, we found that HOTAIR directly targets and binds to miR-217, and that miR-217 directly binds to Zinc finger E-box-binding homeobox 1 (ZEB1). The knockdown of HOTAIR in 60As6 cells significantly reduced the invasion activity and peritoneal dissemination - and significantly prolonged the survival - in the orthotopic tumor mouse model.

CONCLUSION

An EMT-associated pathway (the HOTAIR-miR-217-ZEB1 axis) appears to inhibit peritoneal dissemination and could lead to a novel therapeutic strategy against scirrhous gastric cancer in humans.

Micro‑dimpled surface atelocollagen maintains primary human hepatocytes in culture and may promote their functionality compared with collagen coat culture

Primary human hepatocytes (PHHs) are the gold standard for drug development procedures; however, maintaining functional PHHs in vitro is challenging in conventional collagen-coated cultures. In the present study, we developed a new scaffold comprising high amounts (≥1 mg/cm²) of atelocollagen exposed to ultraviolet radiation to induce cross-linking and improve stability. Scanning and transmission electron microscopy revealed a micro-dimpled surface (MDS) scaffold composed of randomly arranged atelocollagen fibrils. The scaffold was therefore designated as MDS atelocollagen. PHHs cultured on MDS atelocollagen were round with a compact cytoplasm and exhibited enhanced levels of albumin (ALB) secretion and cytochrome P450 (CYP) 3A4 activity. The expression of hepatocyte-related genes, such as serum proteins, drug metabolism-related CYPs, and nuclear receptors, was enhanced in cells cultured on MDS atelocollagen, but not in those cultured on conventional atelocollagen. Moreover, the abnormal gene expression of cell adhesion molecules observed in conventional atelocollagen culture was suppressed when the cells were grown on MDS atelocollagen, thereby suggesting a cell behavior similar to that of in vivo hepatocytes. These results suggest that MDS atelocollagen functionally preserves PHHs while conserving the simplicity of conventional PHH atelocollagen-coated cultures.

siRNA-Based Drug Targeting Human Bcl-xL Against Cancers

The 2006 discovery of the process of RNA interference opened the door to application of this phenomenon for disease treatments. Short interfering RNA (siRNA) can be used to induce RNA interference, and this approach has generated much interest as a new type of nucleic acid-based drugs in humans and other mammals. However, despite the great potential of siRNA-based drugs in cancer therapy, some drawbacks of siRNAs, such as their instability in vivo and poor cellular uptake, remain unresolved. Here, we review the development of siRNA-based drugs targeting the human Bcl-xL gene, an anti-apoptotic factor overexpressed in many cancers, including prostate cancers. We also introduce a novel application of the biomaterial atelocollagen as a vehicle to functionally deliver tumor-specific siRNA molecules in nude mice. Here, we introduce an orthotopic tumor inoculation model in nude mice: the resulting orthotopic tumors more closely replicate the clinical conditions in humans-including the metastasis mode-than ectopic subcutaneously inoculated tumors.

MicroRNAs Associated with Epithelial-Mesenchymal Transition Can Be Targeted to Inhibit Peritoneal Dissemination of Human Scirrhous Gastric Cancers

OBJECTIVES

Scirrhous gastric cancers grow rapidly, and frequently invade the peritoneum. Such peritoneal dissemination properties markedly reduce patient survival. Thus, an effective means for inhibiting peritoneal dissemination is urgently required.

METHODS

We previously established a cell line, HSC-58, from a scirrhous gastric cancer patient, and further successfully isolated a metastatic line, 58As9, in nude mice upon orthotopic inoculation. Using the lines, we examined the mechanism underlying peritoneal dissemination from the viewpoint of microRNA (miRNA) expression.

RESULTS

miRNA array and qRT-PCR analysis showed that the expressions of epithelial-mesenchymal transition (EMT)-associated miRNAs such as miR-200c and miR-141 were significantly low in 58As9. Using 58As9 with stably overexpressing miR-200c, miR-141, or both, together with a luciferase reporter assay, we found that miR-200c targeted zinc finger E-box-binding homeobox 1 (ZEB1) and miR-141 targeted ZEB2. The overexpressed lines reversed the EMT status from mesenchymal to epithelial in 58As9, and significantly reduced the invasion activity and peritoneal dissemination for a significant prolongation of survival in the orthotopic tumor models in nude mice.

CONCLUSIONS

EMT-associated miRNAs such as miR-200c and miR-141 and their target genes ZEB1/ZEB2 have good potential for antiperitoneal dissemination therapy in patients with scirrhous gastric cancers.

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.

Atelocollagen-mediated intravenous siRNA delivery specific to tumor tissues orthotopically xenografted in prostates of nude mice and its anticancer effects

Successful short interfering RNA (siRNA)-based therapy for cancers depends on functional siRNA delivery specific to tumors. In our previous report, we have shown systemic siRNA delivery specific to human prostate cancer cell line PC-3 subcutaneous tumors in nude mice by atelocollagen, a collagen derivative, for formulating a complex with siRNA. We used an siRNA for human Bcl-xL as a model target. In the present study, we examined the antitumor effect on PC-3 orthotopic tumors in nude mice, as these tumors resemble the human clinical situation. The systemic intravenous administration of the complex (siRNA, 50 μg/shot) significantly reduced Bcl-xL expression and induced apoptosis in the tumors, and suppressed their growth. Liver metastasis was also inhibited in the orthotopic model. We successfully showed tumor-specific accumulation of the siRNA by Cy3-labeled siRNA and the direct quantification of the siRNA via reverse-phase high-performance liquid chromatography. The tumor-specific delivery was achieved by the enhanced permeability and retention effect, which is characteristic of macromolecular drugs. The high expression of vascular endothelial growth factor-A in the tumors provided adequate conditions to promote the permeability in the tumors, and to finally form the enhanced permeability and retention effect. In conclusion, our siRNA delivery is specific to the PC-3 orthotopic tumors in nude mice, and is practically feasible to treat tumors.