Phase-change mesoporous Prussian blue nanoparticles for loading paclitaxel and chemo-photothermal therapy of cancer.

Complete treatment of cancer remains a major challenge today. Herein, a biocompatible drug delivery system named as PCM + PTX@mPBs/PEG was constructed. In this system, Paclitaxel (PTX) was blended with phase-change material (PCM) and loaded in mesoporous Prussian blue nanoparticles (mPBs), and chelated with polyethylene glycol at surface. The blank PCM@mPBs/PEG had uniform particle size distribution, large pore size to load drug, excellent photothermal efficiency and good biocompatibility. After loading PTX, PCM + PTX@mPBs/PEG was demonstrated with a high loading capacity and the drug presented temperature-responsive release characteristics. In addition, PTX can be released under the exposure of an NIR laser. In vitro cell experiments showed that nanoparticles can be exposed to near-infrared irradiation to increase uptake in cells, which enhanced anticancer activity. After tail vein injection of PCM + PTX@mPBs/PEG suspension in tumor-bearing mice, PCM + PTX@mPBs/PEG can accumulate at the tumor site through passive transport. The tumor was effectively suppressed by phototherapy and chemotherapy with few side effects. In summary, compared with photothermal therapy or chemotherapy alone, the prepared PCM + PTX@mPBs/PEG showed synergistic photothermal and chemotherapeutic effects on cancer treatment of mice.

A 3C(pro)-dependent bioluminescence imaging assay for in vivo evaluation of anti-enterovirus 71 agents.

Enterovirus 71 (EV71), a member of Picornaviridae, is one of the major pathogens of human hand, foot and mouth disease. EV71 mainly infects children and causes severe neurological complications and even death. The pathogenesis of EV71 infection is largely unknown, and no clinically approved vaccine or effective treatment is available to date. Here we described a novel bioluminescence imaging approach for EV71 detection. In this approach, a plasmid-based reporter was constructed to express the fusion protein AmN(Q/G)BC, a split firefly luciferase mutant, which can be specifically cleaved by EV71 protease 3C(pro). Upon cleavage, the splitting fusion protein restores luciferase activity. Our test confirmed that AmN(Q/G)BC was specifically cleaved by 3C(pro) and EV71 and restored the luciferase activity to a degree that corresponds to the 3C(pro) and virus doses in cells and mice. The anti-EV71 effect of GW5074 and U0126, two mitogen-activated protein kinase (MAPK) inhibitors, was evaluated using this approach to validate its application of screening anti-EV71 agents. We found that the AmN(Q/G)BC reporter efficiently monitored the inhibitory effect of GW5074 and U0126 on EV71 infection under in vitro and in vivo conditions. The data from AmN(Q/G)BC reporter were consistent with Western blotting and histopathology examination. Taken together, this real-time imaging approach can quantitatively monitor the efficacy of anti-EV71 agents and is valuable for anti-EV71 drug screening and evaluation, especially, under in vivo conditions.

Curcumin inhibits the replication of enterovirus 71 in vitro.

Human enterovirus 71 (EV71) is the main causative pathogen of hand, foot, and mouth disease (HFMD) in children. The epidemic of HFMD has been a public health problem in Asia-Pacific region for decades, and no vaccine and effective antiviral medicine are available. Curcumin has been used as a traditional medicine for centuries to treat a diversity of disorders including viral infections. In this study, we demonstrated that curcumin showed potent antiviral effect again EV71. In Vero cells infected with EV71, the addition of curcumin significantly suppressed the synthesis of viral RNA, the expression of viral protein, and the overall production of viral progeny. Similar with the previous reports, curcumin reduced the production of ROS induced by viral infection. However, the antioxidant property of curcumin did not contribute to its antiviral activity, since N-acetyl-l-cysteine, the potent antioxidant failed to suppress viral replication. This study also showed that extracellular signal-regulated kinase (ERK) was activated by either viral infection or curcumin treatment, but the activated ERK did not interfere with the antiviral effect of curcumin, indicating ERK is not involved in the antiviral mechanism of curcumin. Unlike the previous reports that curcumin inhibited protein degradation through ubiquitin-proteasome system (UPS), we found that curcumin had no impact on UPS in control cells. However, curcumin did reduce the activity of proteasomes which was increased by viral infection. In addition, the accumulation of the short-lived proteins, p53 and p21, was increased by the treatment of curcumin in EV71-infected cells. We further probed the antiviral mechanism of curcumin by examining the expression of GBF1 and PI4KB, both of which are required for the formation of viral replication complex. We found that curcumin significantly reduced the level of both proteins. Moreover, the decreased expression of either GBF1 or PI4KB by the application of siRNAs was sufficient to suppress viral replication. We also demonstrated that curcumin showed anti-apoptotic activity at the early stage of viral infection. The results of this study provide solid evidence that curcumin has potent anti-EV71 activity. Whether or not the down-regulated GBF1 and PI4KB by curcumin contribute to its antiviral effect needs further studies.