[Advances of tumor targeting peptides drug delivery system with pH-sensitive activities].

The pH-sensitive peptides drug delivery systems, which target to acidic extracellular environment of tumor tissue, have many advantages in drug delivery. They exhibit a high specificity to tumor and low cytotoxicity, which significantly increase the efficacy of traditional anti-cancer drugs. In recent years the systems have received a great attention. The pH-sensitive peptides drug delivery systems can be divided into five types according to the difference in pH-responsive mechanism,type of peptides and carrier materials. This paper summarizes the recent progresses in the field with a focus on the five types of pH-sensitive peptides in drug delivery systems. This may provide a guideline to design and application of tumor targeting drugs.

Functional properties of a novel hybrid antimicrobial peptide NS: potent antitumor activity and efficient plasmid delivery.

Antimicrobial peptides have been widely recognized as potential candidates for treating tumor, especially for defending against multidrug-resistant cells. Previously, based on the structure of substance P, we have designed a novel class of hybrid antimicrobial peptide NS, which possesses potent antimicrobial activity against a broad spectrum of bacterial pathogens. In this study, we evaluated its cytotoxicity to tumor cells and studied the possible mechanism of action. We showed that NS could efficiently kill tumor cells by rapidly disrupting the tumor cell membrane and inhibiting the DNA synthesis. In addition, we also found that NS could efficiently deliver plasmids into cells and exhibit high transfection efficiency after the introduction of a stearyl moiety to its N-terminus, like many reported cell-penetrating peptides. Taken together, this study revealed the potential multiple functions of NS, providing fundamental support for further therapeutic application as potential antitumor agent.

Design of new acid-activated cell-penetrating peptides for tumor drug delivery.

TH(AGYLLGHINLHHLAHL(Aib)HHIL-NH2), a histidine-rich, cell-penetrating peptide with acid-activated pH response, designed and synthesized by our group, can effectively target tumor tissues with an acidic extracellular environment. Since the protonating effect of histidine plays a critical role in the acid-activated, cell-penetrating ability of TH, we designed a series of new histidine substituents by introducing electron donating groups (Ethyl, Isopropyl, Butyl) to the C-2 position of histidine. This resulted in an enhanced pH-response and improved the application of TH in tumor-targeted delivery systems. The substituents were further utilized to form the corresponding TH analogs (Ethyl-TH, Isopropyl-TH and Butyl-TH), making them easier to protonate for positive charge in acidic tumor microenvironments. The pH-dependent cellular uptake efficiencies of new TH analogs were further evaluated using flow cytometry and confocal laser scanning microscopy, demonstrating that ethyl-TH and butyl-TH had an optimal pH-response in an acidic environment. Importantly, the new TH analogs exhibited relatively lower toxicity than TH. In addition, these new TH analogs were linked to the antitumor drug camptothecin (CPT), while butyl-TH modified conjugate presented a remarkably stronger pH-dependent cytotoxicity to cancer cells than TH and the other conjugates. In short, our work opens a new avenue for the development of improved acid-activated, cell-penetrating peptides as efficient anticancer drug delivery vectors.

Lipid-lowering, hepatoprotective, and atheroprotective effects of the mixture Hong-Qu and gypenosides in hyperlipidemia with NAFLD rats.

BACKGROUND: Hyperlipidemia and its complications are among the most harmful of diseases with a worldwide impact, which creates an urgent imperative to find safe and effective drugs for treatment. HG is mainly composed of two kinds of traditional Chinese medicines (TCM), Hong-Qu and gypenosides. Previously, the ingredients of the mixture mainly composed by Hong-Qu and gypenosides (HG) were widely used for purposes of lipid-lowering, antiatherosclerosis effects, and maintaining cardiovascular health in China. The purpose of this study was to determine whether HG provides any benefit to patients with hyperlipidemia. METHODS: Forty-eight adult male Sprague-Dawley rats with fatty liver disease were randomly divided into six groups: normal, model, two positive controls, and two doses of HG-treated groups. The normal rats were fed a basal diet, and the other rats were fed a high-fat diet. Thereafter, the serum lipid profiles, hepatic steatosis, cytokines, enzymes, and relevant mRNA of rats were analyzed in serum, aorta tissue or hepatic tissues, respectively. RESULTS: After 65 days of feeding the high-fat diet to rats, there were significantly disordered serum lipid profiles, elevated oxidative stress biomarkers, and decreased antiinflammatory cytokines in the serum levels. Additionally, aortic foam cell formation was increased. The gene expression levels including hydroxymethylglutaryl-CoA reductase (HMGR), peroxisome proliferator-activated receptor alpha (PPAR-α), sterol response element-binding protein-1c (SREBP-1c), fatty acid synthase (FAS), acetyl-CoA carboxylase-1 (ACC-1) and carnitine palmitoyl transferase-1(CPT-1) in hepatic tissue were also altered by a high-fat diet fed to Sprague-Dawley rats, and HG treatment significantly resolved and normalized these alterations. Moreover, HG not only caused a significant decrease in the lipid drops on the hepatic tissues, but also restored the antioxidant components. CONCLUSION: HG is beneficial for regulating the stability of blood lipids, has atheroprotective characteristics and may prevent nonalcoholic fatty liver disease (NAFLD), providing more than just a theoretical basis for drug research of cardiovascular disease (CVD) treatment.