The tumor suppressor p53, encoded by the TP53 gene, is recognized as the guardian of the human genome because it regulates many downstream genes to exercise its function in cell cycle and cell death. Recent reports have revealed that several microRNAs (miRNAs) are important components of the p53 tumor suppressor network with miR-125b and miR-504 directly targeting TP53. In this report, we use a screening method to identify that two miRNAs (miR-25 and miR-30d) directly target the 3'UTR of TP53 to down-regulate p53 protein levels and reduce the expression of genes that are transcriptionally activated by p53. Correspondingly, both miR-25 and miR-30d adversely affect apoptotic cell death, cell cycle arrest, and cellular senescence. Inhibition of either miR-25 or miR-30d expression increases endogenous p53 expression and elevates cellular apoptosis in several cell lines, including one from multiple myeloma that has little TP53 mutations. Thus, beyond miR-125b and miR-504, the human TP53 gene is negatively regulated by two more miRNAs: miR-25 and miR-30d.

In biomedical applications, polyethylene glycol (PEG) functionalization has been a major approach to modify nanocarriers such as nano-graphene oxide for particular biological requirements. However, incorporation of a PEG shell poses a significant diffusion barrier that adversely affects the release of the loaded drugs. This study addresses this critical issue by employing a redox-responsive PEG detachment mechanism. A PEGylated nano-graphene oxide (NGO-SS-mPEG) with redox-responsive detachable PEG shell is developed that can rapidly release an encapsulated payload at tumor-relevant glutathione (GSH) levels. The PEG shell grafted onto NGO sheets gives the nanocomposite high physiological solubility and stability in circulation. It can selectively detach from NGO upon intracellular GSH stimulation. The surface-engineered structures are shown to accelerate the release of doxorubicin hydrochloride (DXR) from NGO-SS-mPEG 1.55 times faster than in the absence of GSH. Confocal microscopy shows clear evidence of NGO-SS-mPEG endocytosis in HeLa cells, mainly accumulated in cytoplasm. Furthermore, upon internalization of DXR-loaded NGO with a disulfide-linked PEG shell into HeLa cells, DXR is effectively released in the presence of an elevated GSH reducing environment, as observed in confocal microscopy and flow cytometric experiments. Importantly, inhibition of cell proliferation is directly correlated with increased intracellular GSH concentrations due to rapid DXR release.

A large body of evidence has demonstrated that the ectopic discharges of action potentials in primary afferents, resulted from the abnormal expression of voltage gated sodium channels (VGSCs) in dorsal root ganglion (DRG) neurons following peripheral nerve injury are important for the development of neuropathic pain. However, how nerve injury affects the expression of VGSCs is largely unknown. Here, we reported that selective injury of motor fibers by L5 ventral root transection (L5-VRT) up-regulated Nav1.3 and Nav1.8 at both mRNA and protein level and increased current densities of TTX-S and TTX-R channels in DRG neurons, suggesting that nerve injury may up-regulate functional VGSCs in sensory neurons indirectly. As the up-regulated Nav1.3 and Nav1.8 were highly co-localized with TNF-α, we tested the hypothesis that the increased TNF-α may lead to over-expression of the sodium channels. Indeed, we found that peri-sciatic administration of recombinant rat TNF-α (rrTNF) without any nerve injury, which produced lasting mechanical allodynia, also up-regulated Nav1.3 and Nav1.8 in DRG neurons in vivo and that rrTNF enhanced the expression of Nav1.3 and Nav1.8 in cultured adult rat DRG neurons in a dose-dependent manner. Furthermore, inhibition of TNF-α synthesis, which prevented neuropathic pain, strongly inhibited the up-regulation of Nav1.3 and Nav1.8. The up-regulation of the both channels following L5-VRT was significantly lower in TNF receptor 1 knockout mice than that in wild type mice. These data suggest that increased TNF-α may be responsible for up-regulation of Nav1.3 and Nav1.8 in uninjured DRG neurons following nerve injury.

Cell membrane coated nanoparticles have been designed for inflammation and cancer therapy. An array of cell membranes from cell library were extracted and leveraged to coat a variety of nanoparticles for different diseases.

Polycomb Repressive Complexes 1 and 2 (PRC1 and 2) play a critical role in the epigenetic regulation of transcription during cellular differentiation, stem cell pluripotency, and neoplastic progression. Here we show that the Polycomb Group protein EED, a core component of PRC2, physically interacts with and functions as part of PRC1. Components of PRC1 and PRC2 compete for EED binding. EED functions to recruit PRC1 to H3K27me3 loci and enhances PRC1 mediated H2A ubiquitin E3 ligase activity. Taken together, we suggest an integral role for EED as an epigenetic exchange factor coordinating the activities of PRC1 and 2.

Hybrid mesoporous silica nanoparticles (MSNs), which were synthesized using the co-condensation method and engineered with unique redox-responsive gatekeepers, were developed for studying the glutathione-mediated controlled release. These hybrid nanoparticles constitute a mesoporous silica core that can accommodate the guests (i.e., drug, dye) and the PEG shell that can be connected with the core via disulfide-linker. Interestingly, the PEG shell can be selectively detached from the inner core at tumor-relevant glutathione (GSH) levels and facilitate the release of the encapsulated guests at a controlled manner. The structure of the resulting hybrid nanoparticles (MSNs-SS-mPEG) was comprehensively characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), and nitrogen adsorption/desorption isotherms analysis. The disulfide-linked PEG chains anchored on MSNs could serve as efficient gatekeepers to control the on-off of the pores. Compared with no GSH, fluorescein dye as the model drug loaded into MSNs showed rapid release in 10 mM GSH, indicating the accelerated release after the opening of the pores regulated by GSH. Confocal microscopy images showed a clear evidence of the dye-loaded MSNs-SS-mPEG nanoparticles endocytosis into MCF-7 cells and releasing guest molecules from the pore inside cells. Moreover, in vitro cell viability test using MTT assay indicated that MSNs-SS-mPEG nanoparticles had no obvious cytotoxicity. These results indicate that MSNs-SS-mPEG nanoparticles can be used in the biomedical field.

A series of thermosensitive ABA type triblock poly(e-caprolactone)-bpoly(N-isopropylacrylamide)-b-poly(e-caprolactone) (PCL-PNIPAAm-PCL) copolymers with different molecular weights were synthesized by the combination of ring opening polymerization and reversible addition-fragmentation chain transfer (RAFT) polymerization. The critical micelle concentrations (CMCs) of the resulted four triblock copolymers in aqueous solution were determined to be 33. 8, 39.8, 35.5, and 41.7 mg/L, respectively, by fluorescence spectroscopy using pyrene as a fluorescence probe. Optical absorption measurements showed that the lower critical solution temperatures (LCSTs) of the copolymers were 35.8, 36.2, 35.2, and 36.2 8C, respectively, in distilled water, and 33.9, 34.2, 33.3, 34.6 8C, respectively, in PBS (pH ¼ 6.8, I ¼ 0.1). Transmission electron microscopy (TEM) showed that the self-assembled micelles exhibited a well-defined spherical shape with diameter of around 100 nm. The drug-loaded PCL-PNIPAAm-PCL micelles displayed thermosensitive controlled release behaviors. V V C 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: [3048][3049][3050][3051][3052][3053][3054][3055][3056][3057] 2008

At present, effective drug for treatment of neuropathic pain is still lacking. Recent studies have shown that the ligands of translocator protein (TSPO, 18 kDa), a peripheral receptor for benzodiazepine, modulate inflammatory pain. Here, we report that TSPO was upregulated in astrocytes and microglia in the ipsilateral spinal dorsal horn of rats following L5 spinal nerve ligation (L5 SNL), lasting until the vanishing of the behavioral signs of neuropathic pain (ϳ50 d). Importantly, a single intrathecal injection of specific TSPO agonists Ro5-4864 or FGIN-1-27 at 7 and 21 d after L5 SNL depressed the established mechanical allodynia and thermal hyperalgesia dramatically, and the effect was abolished by pretreatment with AMG, a neurosteroid synthesis inhibitor. Mechanically, Ro5-4864 substantially inhibited spinal astrocytes but not microglia, and reduced the production of tumor necrosis factor-␣ (TNF-␣) in vivo and in vitro. The anti-neuroinflammatory effect was also prevented by AMG. Interestingly, TSPO expression returned to control levels or decreased substantially, when neuropathic pain healed naturally or was reversed by Ro5-4864, suggesting that the role of TSPO upregulation might be to promote recovery from the neurological disorder. Finally, the neuropathic pain and the upregulation of TSPO by L5 SNL were prevented by pharmacological blockage of Toll-like receptor 4 (TLR4). These data suggested that TSPO might be a novel therapeutic target for the treatment of neuropathic pain.