Huae Xu

Resveratrol-loaded polymeric micelles protect cells from Aβ-induced oxidative stress

Resveratrol has been reported to protect several types of cells against beta-amyloid peptide (Abeta) toxicity by scavenging reactive oxygen species (ROS) and inactivating caspase-3. However, other studies found that long-term treatment with resveratrol inhibited cells by inducing ROS generation and activating caspase-3. In the current report, a 48-h incubation of resveratrol at the concentrations of 5 and 10 microM significantly attenuated the viability of PC12 cells and a 12-h pre-incubation of resveratrol did not protect PC12 cells against Abeta exposure (even further inhibited PC12 cells at the concentrations of 10 microM) by acting as a pro-oxidant. Due to the lipophilicity of resveratrol, resveratrol-loaded polymeric micelles basing on amphiphilic block copolymer were developed. Then, the effects of resveratrol-loaded polymeric micelles on the viability and Abeta protection of PC12 cells were investigated. At the equivalent concentrations of 5 and 10 microM resveratrol, a 48-h incubation of resveratrol-loaded nanoparticles did not show toxicity to cells, while 12-h pre-incubation of resveratrol-loaded nanoparticles protected PC12 cells from Abeta-induced damage in a dose dependent manner (1-10 microM) by attenuating intracellular oxidative stress and caspase-3 activity. Further investigations are absolutely needed to evaluate the feasibility and advantages of in vivo applications of resveratrol-loaded nanoparticles.

Paclitaxel/tetrandrine coloaded nanoparticles effectively promote the apoptosis of gastric cancer cells based on "oxidation therapy".

Paclitaxel (Ptx) has demonstrated encouraging activity in the treatment of gastric cancer. Development of drug-containing biodegradable polymeric nanoparticles (np) becomes one of the solutions to relieve side effects of Ptx. However, Ptx-loaded nanoparticles prepared by the nanoprecipitation method are unstable in the aqueous phase. Here we report that tetrandrine (Tet) effectively increases the stability of Ptx-loaded nanoparticles when Tet is coencapsulated with Ptx into mPEG-PCL nanoparticles. The current study demonstrates the synergistic antitumor effect of Tet and Ptx against gastric cancer cells, which provides the basis of coadministration of Tet and Ptx by nanoparticles. It is reported that the cellular chemoresistance to Ptx correlates with intracellular antioxidant capacity and the depletion of cellular antioxidant capacity could enhance the cytotoxicity of Ptx. Tet effectively induces intracellular ROS production. Therefore, the present study provides a promising novel therapeutic strategy basing on oxidation therapy that it could amplify the antitumor effect of paclitaxel by employing Tet as a pro-oxidant. More intracellular Tet accumulation by endocytosis of Ptx/Tet-np than equivalent doses of free drug leads to more intracellular ROS induction, which could efficiently enhance the cytotoxicity of Ptx by sequential inhibition of ROS-dependent Akt pathway and activation of apoptotic pathways, all of which would mediate the superior cytotoxicity of Ptx/Tet-np over free drug. The present results suggest that the codelivery of Ptx and Tet by nanoparticles provides a novel therapeutic strategy basing on oxidation therapy against gastric cancer.

Delivery of ursolic acid (UA) in polymeric nanoparticles effectively promotes the apoptosis of gastric cancer cells through enhanced inhibition of cyclooxygenase 2 (COX-2)

It has been demonstrated that ursolic acid (UA) could effectively induces apoptosis of cancer cells by inhibiting the expression of cyclooxygenase 2 (COX-2), which constitutively expresses in gastric cancer. However, the hydrophobicity of UA increases the difficulty in its potential clinical application, which raises the possibility for its application as a novel model drug in nanoparticle-based delivery system. UA-loaded nanoparticles (UA-NPs) were prepared by a nano-precipitation method using amphilic methoxy poly(ethylene glycol)-polycaprolactone (mPEG-PCL) block copolymers as drug carriers. UA was effectively transported into SGC7901 cells by nanoparticles and localized around the nuclei in the cytoplasms. The in vitro cytotoxicity and apoptosis test indicated that UA-NPs significantly elicited more cell death at almost equivalent dose and corresponding incubation time. Moreover, UA-NPs led to more cell apoptosis through stronger inhibition of COX-2 and activation of caspase 3. The most powerful evidence from this report is that the significant differences between the cytotoxicity of free UA and UA-NPs are closely related to the expression levels of COX-2 and caspase-3, which demonstrates the superiority of UA-NPs over free UA through penetrating cell membrane. Therefore, the study offer an effective way to improve the anticancer efficiency of UA through nano-drug delivery system.

Curcumin delivery by methoxy polyethylene glycol–poly(caprolactone) nanoparticles inhibits the growth of C6 glioma cells

As a potential anticancer agent, curcumin (Cum) has been reported for its chemopreventive and chemotherapeutic activity in a series of cancers through influencing cell cycle arrest, differentiation, apoptosis, etc. Therefore, the potential activity against various cancers of Cum raises the possibility of its application as a novel model drug in nanoparticle-based delivery systems. The current study reported a spherical core-shell structure curcumin-loaded nanoparticle (Cum-np) formed by amphilic methoxy polyethylene glycol-poly(caprolactone) (mPEG-PCL) block copolymers. Characterization tests indicated that Cum was incorporated into mPEG-PCL-based nanoparticles with high encapsulation efficiency due to its lipophilicity. The incorporated Cum could be released from Cum-np in a sustained manner. Cum was effectively transported into the cells by nanoparticles through endocytosis and localized around the nuclei in the cytoplasms. In vitro studies proved that the cytotoxicity of Cum-np would be pro-apoptosis effect against rat C6 glioma cell line in a dose-dependent manner. The present results suggest that Cum-np could be a potential useful chemotherapeutic formulation for malignant glioma therapy. Moreover, the development of traditional Chinese medicine with nanoscale drug formation warrants more intensive research for its clinical applications.

Mitochondrion-Anchoring Photosensitizer with Aggregation-Induced Emission Characteristics Synergistically Boosts the Radiosensitivity of Cancer Cells to Ionizing Radiation

The first mitochondrion-anchoring photosensitizer that specifically generates singlet oxygen (1 O2 ) in mitochondria under white light irradiation that can serve as a highly effective radiosensitizer is reported here, significantly sensitizing cancer cells to ionizing radiation. An aggregation-induced emission luminogen (AIEgen), namely DPA-SCP, is rationally designed with α-cyanostilbene as a simple building block to reveal AIE, diphenylamino (DPA) group as a strong electron donating group to benefit red emission and efficient light-controlled 1 O2 generation, as well as a pyridinium salt as the targeting moiety to ensure specific mitochondrial localization. The AIE signature endows DPA-SCP with the capacity to visualize mitochondria in a fluorescence turn-on mode. It is found that under optimized experimental condition, DPA-SCP with white light does not lead to apoptosis/death of cancer cells, whereas provides an elevated 1 O2 environment in the mitochondria. More importantly, increasing intracellular level of 1 O2 originated from mitochondria is demonstrated to be a generic method to enhance the radiosensitivity of cancer cells with a supra-additive synergistic effect of 0 + 1 > 1. Noteworthy is that DPA-SCP + white light achieves a high SER10 value of 1.62, which is much larger than that of the most popularly used radiosensitizers, gold nanoparticles (1.19), and paclitaxel (1.32).

Enhanced Neuroprotective Effects of Resveratrol Delivered by Nanoparticles on Hydrogen Peroxide-Induced Oxidative Stress in Rat Cortical Cell Culture

Resveratrol (RES) has recently been reported as a potential antioxidant in treatment of ischemia/reperfusion injury through attenuating oxidative stress and apoptosis. However, application of RES is limited for its insolubility and short half-time. Latest evidence raises the possibility of developing nanoparticle-based delivery systems with improved solubility, stability and cytotoxicity of lipophilic drug. Here, we reported first a simple way to produce RES-loaded nanoparticles (RES-NPs) based on poly(N-vinylpyrrolidone)-b-poly(ε-caprolactone) polymer and further evaluated the protective effect of RES-NPs on hydrogen peroxide-induced oxidative stress and apoptosis in rat cortical cell culture. The controlled release pattern of RES-loaded nanoparticles was characterized by in vitro release experiments. Cytotoxicity tests proved cytocompatibility of these nanoparticles with neurons. Shown by coumarin-6 loaded nanoparticles, the uptake of nanoparticles by neurons was considered through endocytosis, which could lead to higher uptake efficiency at lower concentration. Thereby, the hypothesis is raised that RES-NPs could demonstrate enhanced neuroprotection compared to an equivalent dose of free RES at lower concentration, especially. It was further supported by enhanced reduction of LDH release, elimination of ROS and MDA, and attenuation of apoptosis signal (ratio of Bax/Bcl-2, activation of caspase-3). RES-NPs could be a potential treatment needing intensive research for ischemia/reperfusion related disorder including stroke.

Harmine induces apoptosis and inhibits tumor cell proliferation, migration and invasion through down-regulation of cyclooxygenase-2 expression in gastric cancer

Cyclooxygenase-2 (COX-2) plays an important role in the carcinogenesis and progression of gastric cancer. Harmine is reported as a promising drug candidate for cancer therapy; however, effects and action mechanism of harmine on the human gastric cancer cells remain unclear. This study evaluated the anti-tumor effects of harmine on human gastric cancer both in vitro and in vivo. The cell proliferation was determined using MTT colorimetric assay. Apoptosis was measured by DAPI staining and flow cytometry analysis. The wound healing and transwell invasion assays were performed to evaluate the effects of harmine on the migration and invasion of gastric cancer cells. The expression of COX-2, proliferating cell nuclear antigen (PCNA), Bcl-2, Bax and matrix metalloproteinase-2 (MMP-2) was detected by Western blot analysis. Our results showed that harmine significantly inhibited cellular proliferation, migration, invasion and induced apoptosis in vitro, as well as inhibited tumor growth in vivo. In addition, harmine significantly inhibited the expression of COX-2, PCNA, Bcl-2 and MMP-2 as well as increased Bax expression in gastric cancer cells. These results collectively indicate that harmine induces apoptosis and inhibits proliferation, migration and invasion of human gastric cancer cells, which may be mediated by down-regulation of COX-2 expression.

An efficient Trojan delivery of tetrandrine by poly(N-vinylpyrrolidone)-block-poly(ε-caprolactone) (PVP-b-PCL) nanoparticles shows enhanced apoptotic induction of lung cancer cells and inhibition of its migration and invasion.

Earlier studies have demonstrated the promising antitumor effect of tetrandrine (Tet) against a series of cancers. However, the poor solubility of Tet limits its application, while its hydrophobicity makes Tet a potential model drug for nanodelivery systems. We report on a simple way of preparing drug-loaded nanoparticles formed by amphiphilic poly(N-vinylpyrrolidone)-block-poly(ε-caprolactone) (PVP-b-PCL) copolymers with Tet as a model drug. The mean diameters of Tet-loaded PVP-b-PCL nanoparticles (Tet-NPs) were between 110 nm and 125 nm with a negative zeta potential slightly below 0 mV. Tet was incorporated into PVP-b-PCL nanoparticles with high loading efficiency. Different feeding ratios showed different influences on sizes, zeta potentials, and the drug loading efficiencies of Tet-NPs. An in vitro release study shows the sustained release pattern of Tet-NPs. It is shown that the uptake of Tet-NPs is mainly mediated by the endocytosis of nanoparticles, which is more efficient than the filtration of free Tet. Further experiments including fluorescence activated cell sorting and Western blotting indicated that this Trojan strategy of delivering Tet in PVP-b-PCL nanoparticles via endocytosis leads to enhanced induction of apoptosis in the non-small cell lung cancer cell A549 line; enhanced apoptosis is achieved by inhibiting the expression of anti-apoptotic Bcl-2 and Bcl-xL proteins. Moreover, Tet-NPs more efficiently inhibit the ability of cell migration and invasion than free Tet by down-regulating matrix metalloproteinases (MMP)-2 and MMP-9, as well as up-regulating tissue inhibitor of MMP-3 (TIMP-3). Therefore, data from this study not only confirms the potential of Tet in treating lung cancer but also offers an effective way of improving the anticancer efficiency of Tet by nanodrug delivery systems.

Efficient delivery of ursolic acid by poly(N-vinylpyrrolidone)-block-poly (ε-caprolactone) nanoparticles for inhibiting the growth of hepatocellular carcinoma in vitro and in vivo

Previous reports have shown that ursolic acid (UA), a pentacyclic triterpenoid derived from Catharanthus trichophyllus roots, could inhibit the growth of a series of cancer cells. However, the potential for clinical application of UA is greatly hampered by its poor solubility, whereas the hydrophobicity of UA renders it a promising model drug for nanosized delivery systems. In the current study, we loaded UA into amphiphilic poly(N-vinylpyrrolidone)-block-poly (ε-caprolactone) nanoparticles and performed physiochemical characterization as well as analysis of the releasing capacity. In vitro experiments indicated that UA-NPs inhibited the growth of liver cancer cells and induced cellular apoptosis more efficiently than did free UA. Moreover, UA-NPs significantly delayed tumor growth and localized to the tumor site when compared with the equivalent dose of UA. In addition, both Western blotting and immunohistochemistry suggested that the possible mechanism of the superior efficiency of UA-NPs is mediation by the regulation of apoptosis-related proteins. Therefore, UA-NPs show potential as a promising nanosized drug system for liver cancer therapy.

Efficient antitumor effect of co-drug-loaded nanoparticles with gelatin hydrogel by local implantation.

Tetrandrine (Tet) could enhance the antitumor effect of Paclitaxel (Ptx) by increasing intracellular Reactive Oxygen Species (ROS) levels, which leads to the possibility of co-delivery of both drugs for synergistic antitumor effect. In the current study, we reported an efficient, local therapeutic strategy employing effective Tet and Ptx delivery with a nanoparticle-loaded gelatin system. Tet- and Ptx co-loaded mPEG-PCL nanoparticles (P/T-NPs) were encapsulated into the physically cross-linked gelatin hydrogel and then implanted on the tumor site for continuous drug release. The drug-loaded gelatin hydrogel underwent a phase change when the temperature slowly increased. In vitro study showed that Tet/Ptx-loaded PEG-b-PCL nanoparticles encapsulated within a gelatin hydrogel (P/T-NPs-Gelatin) inhibited the growth and invasive ability of BGC-823 cells more effectively than the combination of free drugs or P/T-NPs. In vivo study validated the therapeutic potential of P/T-NPs-Gelatin. P/T-NPs-Gelatin significantly inhibited the activation of p-Akt and the downstream anti-apoptotic Bcl-2 protein and also inducing the activation of pro-apoptotic Bax protein. Moreover, the molecular-modulating effect of P/T-NPs-Gelatin on related proteins varied slightly under the influence of NAC, which was supported by the observations of the tumor volumes and weights. Based on these findings, local implantation of P/T-NPs-Gelatin may be a promising therapeutic strategy for the treatment of gastric cancer.