Can Zhang

Intracellular delivery and antitumor effects of pH-sensitive liposomes based on zwitterionic oligopeptide lipids

pH-sensitive liposomes (HHG2C(18)-L and PEGHG2C(18)-L) based on zwitterionic oligopeptide lipids as anticancer drug carriers were developed and evaluated for effective intracellular delivery and enhanced antitumor activity. The amino acid-based lipids, 1,5-dioctadecyl-l-glutamyl 2-histidyl-hexahydrobenzoic acid (HHG2C(18)) and 1,5-distearyl N-(N-α-(4-mPEG2000) butanedione)-histidyl-l-glutamate (PEGHG2C(18)), were synthesized, which have the multistage pH-response to tumor microenvironmental pH (pH(e), pH 6.0-7.0) and endosomal/lysosomal pH (pH(i), pH 4.0-6.0) successively. HHG2C(18)-L contains HHG2C(18), while PEGHG2C(18)-L includes HHG2C(18) and PEGHG2C(18). Both of them displayed the capability of charge conversion to the surrounding pH. The zeta potentials of HHG2C(18)-L and PEGHG2C(18)-L were negative at pH 7.4, whereas positive at pH 6.5 and more positive at lower pH. Coumarin 6-loaded HHG2C(18)-L (C6/HHG2C(18)-L) and PEGHG2C(18)-L (C6/PEGHG2C(18)-L) showed higher tumor cellular uptake due to electrostatic absorptive endocytosis at pH(e) (pH 6.5), produced proton sponge effect for endo-lysosomal escape, and accumulated to the mitochondria based on stronger positive charge by the hydrolysis of a pH-sensitive linker at pH(i) (pH 5.5 and pH 4.5). Furthermore, temsirolimus (CCI-779)-loaded HHG2C(18)-L (CCI-779/HHG2C(18)-L) and PEGHG2C(18)-L (CCI-779/PEGHG2C(18)-L) had significantly higher antiproliferative and apoptosis inducing effects toward the human renal carcinoma (A498) cells at pH 6.5 relative to that at pH 7.4. The half maximal inhibitory concentration (IC50) of CCI-779/HHG2C(18)-L and CCI-779/PEGHG2C(18)-L were about 3 μg/mL and 5 μg/mL at pH 6.5, 1.67-fold and 1.60-fold improved relative to that at pH 7.4, respectively. The total apoptotic ratio of CCI-779/HHG2C(18)-L and CCI-779/PEGHG2C(18)-L increased from 9.90% and 7.78% at pH 7.4 to 19.53% and 12.10% at pH 6.5, respectively. In vivo, CCI-779/PEGHG2C(18)-L after intravenous administration presented remarkably higher bioavailability and blood persistence compared with unPEGylated CCI-779/HHG2C(18)-L, and had the strongest antitumor efficacy against xenograft renal cancer (Renca) tumor models. Accordingly, the results provide the feasibility of using pH-sensitive zwitterionic oligopeptide lipids to extend the applications of liposomes to efficient anticancer drug delivery in cancer therapy.

The performance of thiol-terminated PEG-paclitaxel-conjugated gold nanoparticles

A series of thiol-terminated polyethylene glycol (PEG)-paclitaxel (PTX) derivatives are designed and synthesized to fabricate PTX-conjugated gold nanoparticles (PTX@GNPs) and improve their overall performance. By extending the molecular weight of PEG from 400 to 1000 Da, the optimized water solubility of the conjugate reaches 184 mg/mL, equal to 4.6 × 10(5) times that of PTX alone (0.4 μg/mL). High drug loading is obtained by eliminating the steric hindrance between PTX molecules on the surface of GNPs. The gold conjugate shows double simultaneous stimulation-induced drug release behavior in the presence of both esterase and high concentrations of glutathione. The synergic release characteristics of this conjugate results in significant performance improvements, including prolonged circulation due to high stability in vivo, targeted release of PTX inside tumor cells, and increased tumor cell killing efficiency. Improving the in vitro properties of the conjugate not only significantly enhances its therapeutic efficacy in a murine liver cancer model, but also allows drug-conjugated gold nanoparticles to be used as a promising nanoprodrug system in the cancer therapeutics.

In vitro evaluation on novel modified chitosan for targeted antitumor drug delivery

In this study, a novel amphiphilic copolymer designed as N-octyl-N-phthalyl-3,6-O-(2-hydroxypropyl) chitosan (OPHPC) were synthesized and then conjugated with folic acid (FA-OPHPC) to produce a targeted drug carrier for tumor-specific drug delivery. OPHPC and FA-OPHPC were characterized by FT-IR, (1)H NMR, (13)C NMR and elemental analysis. Paclitaxel (PTX) loaded OPHPC micelles (PTX-OPHPC) with well-defined spherical shape and homogeneous distribution exhibited drug-loading rate ranging from 33.6% to 45.3% and entrapment efficiency from 50.5% to 82.8%. In the cellular uptake studies, PTX-OPHPC brought about a significantly higher amount of PTX accumulated in human breast adenocarcinoma cell line (MCF-7 cells) compared with Taxol. Moreover, the cellular uptake of PTX in PTX loaded FA-OPHPC micelles (PTX-FA-OPHPC) was 3.2-fold improved in comparison with that of PTX-OPHPC. The results revealed that OPHPC micelle might be a promising drug carrier for promoting PTX cellular uptake and FA-OPHPC micelle could be used as a potential tumor-targeted drug vector.

Thermosensitive micelles–hydrogel hybrid system based on poloxamer 407 for localized delivery of paclitaxel

A thermosensitive micelles-hydrogel hybrid system based on Poloxamer 407 (P407) was prepared to resolve the fast erosion and low loading capability of lipophilic drug of P407 gels for local chemotherapy. Different amounts of glutaraldehyde (GA) were applied to generate cross-linked networks with carboxymethyl chitosan (CMCS) interpenetrated in P407 gels, in which paclitaxel (PTX)-loaded N-octyl-O-sulfate chitosan micelles (PTX-M) were dispersed uniformly. The in vitro characteristics of CMCS-modified P407 gels (PTX-M-MG) were performed by examining the viscosity, swelling ratio, mechanical property, and drug release, while the in vivo evaluation included tissue distribution and anticancer efficacy through intratumoral administration in hepatoma solidity cell (Heps) tumor-bearing mice. The results showed that PTX-M-MG containing 0.05% (w/v) GA possessed lower viscosity, higher swelling ratio, stronger mechanical property, and longer term drug release, in which the loading efficiency of PTX was enlarged by the introduction of PTX-M. Moreover, PTX-M-MG revealed a prolonged retention at tumor sites, lasting for 20 days, and a superior tumor inhibition rate (64.27%) with reduced toxicity compared with Taxol(®) , PTX-M, and PTX-M loaded unmodified P407 gels (PTX-M-P407). It can be concluded that PTX-M-MG is a promising local delivery system for hydrophobic drug in cancer therapy, providing both improved efficacy and relieved side effects.

Endoplasmic reticulum stress mediating downregulated StAR and 3-beta-HSD and low plasma testosterone caused by hypoxia is attenuated by CPU86017-RS and nifedipine

BackgroundHypoxia exposure initiates low serum testosterone levels that could be attributed to downregulated androgen biosynthesizing genes such as StAR (steroidogenic acute regulatory protein) and 3-beta-HSD (3-beta-hydroxysteroid dehydrogenase) in the testis. It was hypothesized that these abnormalities in the testis by hypoxia are associated with oxidative stress and an increase in chaperones of endoplasmic reticulum stress (ER stress) and ER stress could be modulated by a reduction in calcium influx. Therefore, we verify that if an application of CPU86017-RS (simplified as RS, a derivative to berberine) could alleviate the ER stress and depressed gene expressions of StAR and 3-beta-HSD, and low plasma testosterone in hypoxic rats, these were compared with those of nifedipine.MethodsAdult male Sprague-Dawley rats were randomly divided into control, hypoxia for 28 days, and hypoxia treated (mg/kg, p.o.) during the last 14 days with nifedipine (Nif, 10) and three doses of RS (20, 40, 80), and normal rats treated with RS isomer (80). Serum testosterone (T) and luteinizing hormone (LH) were measured. The testicular expressions of biomarkers including StAR, 3-beta-HSD, immunoglobulin heavy chain binding protein (Bip), double-strand RNA-activated protein kinase-like ER kinase (PERK) and pro-apoptotic transcription factor C/EBP homologous protein (CHOP) were measured.ResultsIn hypoxic rats, serum testosterone levels decreased and mRNA and protein expressions of the testosterone biosynthesis related genes, StAR and 3-beta-HSD were downregulated. These changes were linked to an increase in oxidants and upregulated ER stress chaperones: Bip, PERK, CHOP and distorted histological structure of the seminiferous tubules in the testis. These abnormalities were attenuated significantly by CPU86017-RS and nifedipine.ConclusionDownregulated StAR and 3-beta-HSD significantly contribute to low testosterone in hypoxic rats and is associated with ER stress which mediates testis damage caused by oxygen deprivation. CPU86017-RS is potential in ameliorating hypoxia-induced testicular injuries, possibly by its calcium antagonist effects on the testis.

Apocynin and raisanberine alleviate intermittent hypoxia induced abnormal StAR and 3β-HSD and low testosterone by suppressing endoplasmic reticulum stress and activated p66Shc in rat testes.

We hypothesized that hypoxia induced testicular damage is mediated by an activated NADPH oxidase (NOX), therefore, APO (apocynin) an inhibitor of NOX and raisanberine (RS), a calcium influx inhibitor were tested if they could attenuate hypoxic toxicity to the testis. Male Sprague-Dawley rats were exposed to hypoxia (10±0.5% O₂) for 17d and intervened with APO and RS in the last 6d. Histological changes and expression of pro-inflammation factors were evaluated in vivo. Biomarkers in isolated Leydig cells incubated with H₂O₂ were also assayed in vitro. Hypoxic rats displayed lower serum testosterone and higher LH and FSH. Upregulation of p22/p47(phox), NOX2, MMP9, PERK and p66Shc was associated with downregulation of StAR, 3β-HSD and Cx43 in the hypoxia testis, revealed by Western blot and immunohistochemical assay, respectively. APO and RS at least partially normalize hypoxia caused male hypogonadism by suppressing ER stress, and p66Shc in testes.

Glutathione-mediated drug release from Tiopronin-conjugated gold nanoparticles for acute liver injury therapy.

Tiopronin-conjugated gold nanoparticles (TPN@GNPs), with glutathione (GSH)-responsive drug release property, were developed for acute liver injury therapy. The TPN@GNPs were prepared using a one-pot synthesis method and characterized by UV-vis and transmission electronic microscopy methods. The TPN@GNPs displayed typical surface plasmon resonance of nanogold with a narrow size distribution (ca. 2 nm). The in vitro drug release profiles of the conjugates indicated that TPN@GNPs were able to release TPN in a sustained fashion for 4 h at a simulated intracellular level of GSH. pH values or ionic strengths of the release media had no obvious influence on TPN release from the surface of nanoparticles. The pharmacokinetic studies in rats showed that the TPN@GNPs had longer MRT (7.71 h) than TPN (3.96 h), indicating sustained release pattern of TPN@GNPs in vivo. The sustained release of TPN at the relative high GSH concentration could ameliorate the instability of TPN and enable the drug release in the target cells. Although the IC50 value of TPN@GNPs with TPN/AuCl4(-) of 3:1 (mol/mol) showed slight increase in comparison with that of the free TPN in HepG2 cells (1.26±1.07 vs. 1.73±1.16 mg/mL), the TPN@GNPs displayed better effects over TPN in the treatment of acute liver injury in vivo. In a liver injury mice model induced by CCl4, the histological analysis showed both the TPN@GNPs and free TPN group could repair the liver injury. In addition, the biochemical parameters showed TPN@GNPs could reduced the aminotransferase to a lower level compared with TPN, which might be due to the sustained drug release and passive liver targeting properties of TPN@GNPs. It demonstrated that gold nanoparticle-based drug delivery system allowed smart functions and superior properties by taking advantages of the unique small size effects and surface chemical properties.

Novel nonsecosteroidal VDR agonists with phenyl-pyrrolyl pentane skeleton.

In order to find the vitamin D receptor (VDR) ligand whose VDR agonistic activity is separated from the calcemic activity sufficiently, novel nonsecosteroidal analogs with phenyl-pyrrolyl pentane skeleton were synthesized and evaluated for the VDR binding affinity, antiproliferative activity in vitro and serum calcium raising ability in vivo (tacalcitol used as control). Among them, several compounds showed varying degrees of VDR agonistic and growth inhibition activities of the tested cell lines. The most effective compound 2g (EC₅₀: 1.06 nM) exhibited stronger VDR agonistic activity than tacalcitol (EC₅₀: 7.05 nM), inhibited the proliferations of HaCaT and MCF-7 cells with IC₅₀ of 2.06 μM and 0.307 μM (tacalcitol: 2.07 μM and 0.057 μM) and showed no significant effect on serum calcium.

Hypoxia/oxidative stress alters the pharmacokinetics of CPU86017-RS through mitochondrial dysfunction and NADPH oxidase activation

Aim:Hypoxia/oxidative stress can alter the pharmacokinetics (PK) of CPU86017-RS, a novel antiarrhythmic agent. The aim of this study was to investigate the mechanisms underlying the alteration of PK of CPU86017-RS by hypoxia/oxidative stress.Methods:Male SD rats exposed to normal or intermittent hypoxia (10% O2) were administered CPU86017-RS (20, 40 or 80 mg/kg, ig) for 8 consecutive days. The PK parameters of CPU86017-RS were examined on d 8. In a separate set of experiments, female SD rats were injected with isoproterenol (ISO) for 5 consecutive days to induce a stress-related status, then CPU86017-RS (80 mg/kg, ig) was administered, and the tissue distributions were examined. The levels of Mn-SOD (manganese containing superoxide dismutase), endoplasmic reticulum (ER) stress sensor proteins (ATF-6, activating transcription factor 6 and PERK, PRK-like ER kinase) and activation of NADPH oxidase (NOX) were detected with Western blotting. Rat liver microsomes were incubated under N2 for in vitro study.Results:The Cmax, t1/2, MRT (mean residence time) and AUC (area under the curve) of CPU86017-RS were significantly increased in the hypoxic rats receiving the 3 different doses of CPU86017-RS. The hypoxia-induced alteration of PK was associated with significantly reduced Mn-SOD level, and increased ATF-6, PERK and NOX levels. In ISO-treated rats, the distributions of CPU86017-RS in plasma, heart, kidney, and liver were markedly increased, and NOX levels in heart, kidney, and liver were significantly upregulated. Co-administration of the NOX blocker apocynin eliminated the abnormalities in the PK and tissue distributions of CPU86017-RS induced by hypoxia/oxidative stress. The metabolism of CPU86017-RS in the N2-treated liver microsomes was significantly reduced, addition of N-acetylcysteine (NAC), but not vitamin C, effectively reversed this change.Conclusion:The altered PK and metabolism of CPU86017-RS induced by hypoxia/oxidative stress are produced by mitochondrial abnormalities, NOX activation and ER stress; these abnormalities are significantly alleviated by apocynin or NAC.

CPU86017-RS attenuate hypoxia-induced testicular dysfunction in mice by normalizing androgen biosynthesis genes and pro-inflammatory cytokines

Aim:Downregulation of androgen biosynthesis genes StAR (steroidogenic acute regulatory) and 3β-HSD (3β-hydroxysteroid dehydrogenase) contributes to low testosterone levels in hypoxic mice and is possibly related to increased expression of pro-inflammatory cytokines in the testis. The aim of this study is to investigate the effects of CPU86017-RS that block Ca2+ influx on hypoxia-induced testis insult in mice.Methods:Male ICR mice were divided into 5 groups: control group, hypoxia group, hypoxia group treated with nifedipine (10 mg/kg), hypoxia groups treated with CPU86017-RS (60 or 80 mg/kg). Hypoxia was induced by placing the mice in a chamber under 10%±0.5% O2 for 28 d (8 h per day). The mice were orally administered with drug in the last 14 d. At the end of experiment the testes of the mice were harvested. The mRNA and protein levels of StAR, 3β-HSD, connexin 43 (Cx43), matrix metalloprotease 9 (MMP9), endothelin receptor A (ETAR) and leptin receptor (OBRb) were analyzed using RT-PCR and Western blotting, respectively. The malondialdehyde (MDA), lactate dehydrogenase (LDH), succinate dehydrogenase (SDH) and acid phosphatase (ACP) levels were measured using biochemical kits. Serum testosterone concentration was measured with radioimmunoassay.Results:Hypoxia significantly increased the MDA level, and decreased the LDH, ACP and SDH activities in testes. Meanwhile, hypoxia induced significant downregulation of StAR and 3β-HSD in testes responsible for reduced testosterone biosynthesis. It decreased the expression of Cx43, and increased the expression of MMP9, ETAR and OBRb, leading to abnormal testis function and structure. These changes were effectively diminished by CPU86017-RS (80 mg/kg) or nifedipine (10 mg/kg).Conclusion:Low plasma testosterone level caused by hypoxia was due to downregulation of StAR and 3β-HSD genes, in association with an increased expression of pro-inflammatory cytokines. These changes can be alleviated by CPU86017-RS or nifedipine.