Commercial anti-obesity drugs acting in the gastrointestinal tract or the central nervous system have been shown to have limited efficacy and severe side effects. Anti-obesity drug development is thus focusing on targeting adipocytes that store excess fat. Here, we show that an adipocyte-targeting fusion-oligopeptide gene carrier consisting of an adipocyte-targeting sequence and 9-arginine (ATS-9R) selectively transfects mature adipocytes by binding to prohibitin. Injection of ATS-9R into obese mice confirmed specific binding of ATS-9R to fat vasculature, internalization and gene expression in adipocytes. We also constructed a short-hairpin RNA (shRNA) for silencing fatty-acid-binding protein 4 (shFABP4), a key lipid chaperone in fatty-acid uptake and lipid storage in adipocytes. Treatment of obese mice with ATS-9R/shFABP4 led to metabolic recovery and body-weight reduction (>20%). The ATS-9R/shFABP4 oligopeptide complex could prove to be a safe therapeutic approach to regress and treat obesity as well as obesity-induced metabolic syndromes.
Small interfering RNA (siRNA) has emerged as a therapeutic strategy for various diseases due to its target-specific gene silencing; however, its relatively high molecular weight, negative charge, and low stability hamper in vitro and in vivo applications. Approaches to overcome those drawbacks have relied on nonviral siRNA carriers based on cationic polymers or peptides. Nevertheless, cationic polymer-based siRNA carriers have yet to resolve intrinsic problems such as cytotoxicity and immunogenicity. An environment-sensitive carrier was recently proposed to enhance siRNA bioactivity and to reduce the carrier safety issues. Only a few studies, however, have shown cytoplasm-sensitive dissociation of the polyplex. In the present study, we clearly demonstrated decondensation of siRNA/poly(oligo-D-arginine) polyplex in the cytoplasm in response to intracellular glutathione (GSH) and the enhanced bioactivity of siRNA against VEGF (siVEGF) used as a model both in vitro and in an animal model. Reducible poly(oligo-D-arginine) (rPOA) rapidly dissociated in the cytoplasm, resulting in fast siRNA release to its target location while maintaining siRNA bioactivity both in vitro and in vivo.
A wide variety of drug delivery systems have been developed for the delivery of anticancer agents. One of the most frequently used natural biomaterials in drug delivery systems is polysaccharides; however, they are difficult to digest and to eliminate from the body after systemic administration due to their high molecular weight natures and the absence of degrading enzymes. Therefore, the development of degradable and eliminable natural biomaterials is critical for successful in vivo applications. In the present study, we report the development of self-assembled biodegradable nanoparticles based on recombinant human gelatin (rHG) modified with alpha-tocopheryl succinate (TOS). The rHG-TOS nanoparticles efficiently encapsulated 17-AAG (17-allylamino-17-demethoxygeldanamycin), a small molecular anticancer drug targeting heat shock protein 90. The formation of 17-AAG-loaded nanoparticles was confirmed using TEM and dynamic light scattering analysis and found to be within the size of 90-220 nm. The loading efficiency, sustained release pattern, and stability of 17-AAG from the rHG-TOS nanoparticles were determined using HPLC. Furthermore, the passive targeting of rHG-TOS nanoparticles to the tumor area via enhanced permeability and retention effect was examined by noninvasive live animal imaging in a tumor mouse model. Finally, the 17-AAG-loaded nanoparticles were nonimmunogenic and more efficient than free 17-AAG in manifesting an anticancer effect in the tumor model. Overall, our data demonstrate rHG-TOS as a promising tool for the delivery of 17-AAG featuring therapeutic efficacy and biocompatibility.
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