PAK4-relevant proliferation reduced by cell autophagy via p53/mTOR/p-AKT signaling.

Background: P21-activated kinase 4 (PAK4) involves in cell proliferation in cancer and mutually regulates with p53, a molecule is demonstrated to control cell autophagy by mammalian target of rapamycin (mTOR)/protein kinase B (AKT) signaling. Since the signaling exhibits an association with PAK family members in cell autophagy, it implies that PAK4-relevant proliferation may be impacted by autophagy via p53 with a lack of evidence in cancer cells. Methods: In this research, transient and stable PAK4-knockdown human hepatocarcinoma cell lines (HepG2) were constructed by transfection of PAK4-RNA interference (RNAi) plasmid and lentivirus containing PAK4-RNAi plasmid, respectively. We investigated cell proliferation using methyl thiazolyl tetrazolium (MTT) and Cell Counting Kit 8 (CCK8) assays, cell cycle by flow cytometry (FCM) and cell autophagy by monodansylcadaverine (MDC) staining and autophagic biomarker's expression, and detected the expressions of p53, mTOR, phosphorylated-AKT (p-AKT) and AKT by immunofluorescence and western blot to explore the mechanism. Results: We successfully constructed transient and stable PAK4-knockdown HepG2 cell lines, and detected dysfunction of the cells' proliferation. An increased expression of p53, as a molecule of cell-cycle-surveillance on G1/S phase, was demonstrated in the cells although the cell cycle blocked at G2/M. And then, we detected increased autophagosome and autophagic biomarker LC3-II, and decreased expressions in p-AKT and mTOR. Conclusions: The proliferation is reduced in PAK4-knockdown HepG2 cells, which is relative to not only cell cycle arrest but also cell autophagy, and p53/mTOR/p-AKT signaling involves in the cell progress. The findings provide a new mechanism on PAK4 block in cancer therapy.

Cancer-educated mesenchymal stem cells promote the survival of cancer cells at primary and distant metastatic sites via the expansion of bone marrow-derived-PMN-MDSCs.

Bone marrow mesenchymal stem cells (BMSCs) are multipotent stromal cells that can differentiate into a variety of cell types. BMSCs are chemotactically guided towards the cancer cells and contribute to the formation of a cancer microenvironment. The homing of BMSCs was affected by various factors. Disseminated tumour cells (DTCs) in distant organs, especially in the bone marrow, are the source of cancer metastasis and cancer relapse. DTC survival is also determined by the microenvironment. Here we aim to elucidate how cancer-educated BMSCs promote the survival of cancer cells at primary tumour sites and distant sites. We highlight the dynamic change by identifying different gene expression signatures in intratumoral BMSCs and in BMSCs that move back in the bone marrow. Intratumoral BMSCs acquire high mobility and displayed immunosuppressive effects. Intratumoral BMSCs that ultimately home to the bone marrow exhibit a strong immunosuppressive function. Cancer-educated BMSCs promote the survival of lung cancer cells via expansion of MDSCs in bone marrow, primary tumour sites and metastatic sites. These Ly6G+ MDSCs suppress proliferation of T cells. CXCL5, nitric oxide and GM-CSF produced by cancer-educated BMSCs contribute to the formation of malignant microenvironments. Treatment with CXCL5 antibody, the iNOS inhibitor 1400w and GM-CSF antibody reduced MDSC expansion in the bone marrow, primary tumour sites and metastatic sites, and promoted the efficiency of PD-L1 antibody. Our study reveals that cancer-educated BMSCs are the component of the niche for primary lung cancer cells and DTCs, and that they can be the target for immunotherapy.

Activity Origin and Design Principles for Oxygen Reduction on Dual-Metal-Site Catalysts: A Combined Density Functional Theory and Machine Learning Study.

Dual-metal-site catalysts (DMSCs) are emerging as a new frontier in the field of oxygen reduction reaction (ORR). However, there is a lack of design principles to provide a universal description of the relationship between intrinsic properties of DMSCs and the catalytic activity. Here, we identify the origin of ORR activity and unveil design principles for graphene-based DMSCs by means of density functional theory computations and machine learning (ML). Our results indicate that several experimentally unexplored DMSCs can show outstanding ORR activity surpassing that of platinum. Remarkably, our ML study reveals that the ORR activity of DMSCs is intrinsically governed by some fundamental factors, such as electron affinity, electronegativity, and radii of the embedded metal atoms. More importantly, we propose predictor equations with acceptable accuracy to quantitatively describe the ORR activity of DMSCs. Our work will accelerate the search for highly active DMSCs for ORR and other electrochemical reactions.

Super Moisture-Absorbent Gels for All-Weather Atmospheric Water Harvesting.

Atmospheric water harvesting (AWH)-producing fresh water via collecting moisture from air-enables sustainable water delivery without geographical and hydrologic limitations. However, the fundamental design principle to prepare materials that can convert the water vapor in the air to collectible liquid water is still mostly unknown. Here, a super moisture-absorbent gel, which is composed of hygroscopic polypyrrole chloride penetrating in hydrophilicity-switchable polymeric network of poly N-isopropylacrylamide, is shown. Based on such design, a high-efficiency water production by AWH has been achieved in a broad range of relative humidity. The synergistic effect enabled by the molecular level integration of hygroscopic and hydrophilicity-switchable polymers in a network architecture presents controllable interaction between the gel and water molecules, simultaneously realizing efficient vapor capturing, in situ water liquefaction, high-density water storage and fast water releasing under different weather conditions. Being an effective method to regulate migration of water molecules, such design represents a novel strategy to improve the AWH, and it is also fundamental to other water management systems for environmental cooling, surficial moisturizing and beyond.

Cationic Covalent Organic Framework Nanosheets for Fast Li-Ion Conduction.

Covalent organic frameworks (COFs) with their porous structures that are accommodative of Li salts are considered to be potential candidates for solid-state fast Li+ conductors. However, Li salts simply infiltrated in the pores of solid-state COFs tend to be present in closely associate ion pairs, resulting in slow ionic diffusion dynamics. Here we incorporate cationic skeleton into the COF structure to split the Li salt ion pair through stronger dielectric screening. It is observed that the concentration of free Li+ ions in the resulting material is drastically increased, leading to a significantly improved Li+ conductivity in the absence of any solvent (up to 2.09 × 10-4 S cm-1 at 70 °C).

Porous germanene as a highly efficient gas separation membrane.

Using a gas separation membrane as a simple gas separation device has an obvious advantage because of the low energy consumption and pollution-free manufacturing. The first-principles calculations used in this work show that germanene with its divacancy is an excellent material for use as a hydrogen (H2) and helium (He) separation membrane, and that it displays an even better competitive advantage than porous graphene and porous silicene. Porous germanene with its divacancy is chemically inert to gas molecules, because it lacks additional atoms to protect the edged dangling germanium atoms in defects, and thus shows great advantages for gas separation over previously prepared graphene. The energy barriers to H2 and He penetrating porous germanene are quite low, and the permeabilities to H2 and He are high. Furthermore, the selectivities of porous germanene for H2 and He relative to other gas molecules are high, up to 1031 and 1027, respectively, which are superior to those of porous graphene (1023) and porous silicene (1013); thus the separation efficiency of porous germanene is much higher than that of porous graphene and porous silicene. Therefore, germanene is a favorable candidate as a gas separation membrane material. At the same time, the successful synthesis of germanene in the laboratory means that it is possible to use it in real applications.

Fluorescence in situ hybridization is superior for monitoring Epstein Barr viral load in infectious mononucleosis patients.

BACKGROUND: Epstein Barr virus (EBV) plays a causal role in some diseases, including infectious mononucleosis, lymphoproliferative diseases and nasopharyngeal carcinoma. Detection of EBV infection has been shown to be a useful tool for diagnosing EBV-related diseases. In the present study, we compared the performance of molecular tests, including fluorescence in situ hybridization (FISH) and EBV real-time PCR, to those of serological assays for the detection of EBV infection. METHODS: Thirty-eight patients with infectious mononucleosis (IM) were enrolled, of whom 31 were diagnosed with a mild type, and seven were diagnosed with IM with haemophagocytic lymphohistiocytosis and chronic active EBV infection. Twenty healthy controls were involved in the study. The atypical lymphocytes in peripheral blood were detected under a microscope and the percentage of positive cells was calculated. EBV DNA load in peripheral blood was detected using real-time PCR. The FISH assay was developed to detect the EBV genome from peripheral blood mononuclear cells (PBMC). Other diagnosis methods including the heterophil agglutination (HA) test and EBV-VCA-IgM test, to detect EBV were also compared. SPSS17.0 was used for statistical analysis. RESULTS: In all, 5-41% atypical lymphocytes were found among the PBMC in mild IM patients, whereas 8-51% atypical lymphocytes were found in IM patients with haemophagocytic lymphohistiocytosis and chronic active EBV infection patients. There was no significant difference in the ratios of atypical lymphoma between patients of the different types. We observed that 71.2% of mild IM patients and 85.7% of IM patients with haemophagocytic lymphohistiocytosis and chronic active EBV infection patients were positive for EBV-VCA-IgM. EBV-VCA-IgM was negative in all healthy control subjects. In addition, 67.1% of mild IM patients tested heterophile antibody positive, whereas 71.4% of IM patients with haemophagocytic lymphohistiocytosis and chronic active EBV infection tested positive. EBV DNA detected using real-time PCR was observed in 89.5% of these IM patients. The EBV genome was detected by the FISH assay in 97.4% of the IM patients. The EB viral loads detected by FISH and real-time PCR increased with the severity of IM. The EBV genome was detected in almost all the PBMC of IM with haemophagocytic lymphohistiocytosis and chronic active EBV infection patients. CONCLUSION: Molecular tests, including FISH and EBV real-time PCR, are more sensitive than serological assays for the detection of EBV infection. The FISH assay detecting EBV copies in unfractionated whole blood is preferable and superior to plasma real-time PCR in its reflection of the absolute viral burden circulating in the patients.

Polar Ketone-Functionalized Metal-Organic Framework Showing a High CO2 Adsorption Performance.

The incorporation of various functionalities into porous metal-organic frameworks (MOFs) represents an efficacious strategy to improving their gas adsorption properties. In this work, a carbonylated tetracarboxylic acid ligand (5,5'-carbonyldiisophthalic acid) was synthesized, and a ketone-functionalized MOF with exposed metal sites based on this ligand was formed successfully. Structural analysis reveals that the new MOF possesses channels decorated by the carbonyl groups and rhombicuboctahedral cages, with open CuII sites pointing toward the cage center. The framework exhibits exceptionally high CO2 (46.7 wt % at 273 K and 1 bar) and H2 (2.8 wt % at 77 K and 1 bar) uptake. Furthermore, it displays high selectivities of CO2 adsorption over N2 and CH4 at 298 K.

MicroRNA-126 inhibits colon cancer cell proliferation and invasion by targeting the chemokine (C-X-C motif) receptor 4 and Ras homolog gene family, member A, signaling pathway.

MicroRNA-126 (miR-126) suppresses the migration, proliferation and invasion of colon cancer cells. However, the underlying mechanisms of miR-126 in colon cancer have not been fully elucidated. In this study, in vivo experiments revealed that miR-126 inhibits colon cancer growth and metastasis. Furthermore, miR-126 was down-regulated in human colon cancer tissue, and its expression was inversely correlated with TNM stage and metastasis of patients. Low level of miR-126 identified patients with poor prognosis. And we found that miR-126 expression was negatively correlated with the expression levels of chemokine (C-X-C motif) receptor 4 (CXCR4) and components of signaling pathway of Ras homolog gene family, member A (RhoA) in vitro and in vivo. Moreover, we verified that miR-126 negatively regulated CXCR4 and RhoA signaling in vitro. In addition, either in miR-126-overexpressing or in miR- 126-silenced colon cancer cells, the restoration of CXCR4 could significantly reverse the proliferation and invasion, as well as abolish the effects of miR-126 on RhoA signaling pathway. Collectively, these results demonstrated that miR-126 acts as a tumor suppressor by inactivating RhoA signaling via CXCR4 in colon cancer. And miR-126 may serve as a prognostic marker for monitoring and treating colon cancer.

Cavity partition and functionalization of a [2+3] organic molecular cage by inserting polar P[double bond, length as m-dash]O bonds.

The cavity of a [2+3] organic molecular cage was partitioned and functionalized by inserting inner-directed P[double bond, length as m-dash]O bonds, which shows CO2 capture and CH4 exclusion due to the size-matching and polarity effects. Computational results demonstrate that the successful segmentation via polar P[double bond, length as m-dash]O bonds facilitates the CO2 molecules to reside selectively inside the cavity.

A cycloparaphenylene nanoring with graphenic hexabenzocoronene sidewalls.

Herein we report the synthesis of a novel hexabenzocoronene-containing cycloparaphenylene carbon nanoring, cyclo[12]-paraphenylene[2]-2,11-hexabenzocoronenylene, by metal-mediated cross-coupling reactions. The nanoring was accomplished by rationally designed palladium-catalyzed coupling of diborylhexabenzocoronene and L-shaped cyclohexane units, followed by nickel-mediated C-Br/C-Br coupling and the aromatization of cyclohexane moieties. The structure was confirmed by NMR and HR-MS. Especially, the cycloparaphenylene structure is firstly observed by STM. The photophysical properties were studied using UV-Vis spectroscopy, photoluminescence (PL) spectroscopy, and theoretical calculations.

Activation of anaphase-promoting complex by p53 induces a state of dormancy in cancer cells against chemotherapeutic stress.

Cancer dormancy is a stage in tumor progression in which residual disease remains occult and asymptomatic for a prolonged period. Cancer cell dormancy is the main cause of cancer recurrence and failure of therapy. However, cancer dormancy is poorly characterized and the mechanisms of how cancer cells develop dormancy and relapse remain elusive. In this study, 5- fluorouracil (5-FU) was used to induce cancer cell dormancy. We found that cancer cells escape the cytotoxicity of 5-FU by becoming "dormant". After exposure to 5-FU, residual non-small cell lung cancer (NSCLC) cells underwent epithelial-mesenchymal transition (EMT), followed by mesenchymal-epithelial transition (MET). These EMT-transformed NSCLC cells were in the state of cell quiescence where cells were not dividing and were arrested in the cell cycle in G0-G1. The dormant cells underwent an EMT showed characteristics of cancer stem cells. P53 is strongly accumulated in response to 5-FU-induced dormant cells through the activation of ubiquitin ligase anaphase-promoting complex (APC/C) and TGF-ß/Smad signaling. In contrast to the EMT-transformed cells, MET-transformed cells showed an increased ability to proliferate, suggesting that dormant EMT cells were reactivated in the MET process. During the EMT-MET process, DNA repair including nonhomologous end joining (NHEJ) and homologous recombination (HR) is critical to dormant cell reactivation. Our findings provide a mechanism to unravel cancer cell dormancy and reactivation of the cancer cell population.

A Density Functional Study of the Nonlinear Optical Properties of Edge-Functionalized Nonplanar Nanographenes.

The atomically precise edge chlorination of nanographenes has recently been reported as a crucial technology of functionalization through which the planar structure and optical properties of nanographenes can be significantly changed. To check the effects of molecular size, geometrical symmetry and edge functionalization of nanographenes on their optical properties, a series of nanographenes is studied in the framework of density functional theory with the B3LYP functional. Our results indicate that edge functionalization remarkably changes the nonlinear optical properties and increases the anisotropy of nanographenes compared to the effects of the molecular size and system geometric symmetry. Furthermore, the nonlinear optical properties of nanographenes can be tuned by precise edge functionalization, which opens a new avenue for using nanographenes as nonlinear optical materials.

Rational Design of Cathode Structure for High Rate Performance Lithium-Sulfur Batteries.

Practical applications of Li-S batteries require not only high specific capacities and long cycle lifetimes but also high rate performance. We report a rationally designed Li-S cathode, which consists of a freestanding composite thin film assembled from S nanoparticles, reduced graphene oxide (rGO), and a multifunctional additive poly(anthraquinonyl sulfide) (PAQS). The S nanoparticles provide a high initial specific capacity, and the layered and porous rGO structure provides electron and ion transport paths and restricts polysulfide shuttling. PAQS is not only a highly efficient sulfide trapping agent but also an excellent Li(+) conductor, which benefits the battery reaction kinetics at a high rate. The resulting cathode exhibits an initial specific capacity of 1255 mAh g(-1) with a decay rate as low as 0.046% per cycles over 1200 cycles. Importantly, it displays a reversible capacity of 615 mAh g(-1) when discharged at a high rate of 8 C (13.744 A g(-1)).

Mono-Mercury Doping of Au25 and the HOMO/LUMO Energies Evaluation Employing Differential Pulse Voltammetry.

Controlling the bimetal nanoparticle with atomic monodispersity is still challenging. Herein, a monodisperse bimetal nanoparticle is synthesized in 25% yield (on gold atom basis) by an unusual replacement method. The formula of the nanoparticle is determined to be Au24Hg1(PET)18 (PET: phenylethanethiolate) by high-resolution ESI-MS spectrometry in conjunction with multiple analyses including X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). X-ray single-crystal diffraction reveals that the structure of Au24Hg1(PET)18 remains the structural framework of Au25(PET)18 with one of the outer-shell gold atoms replaced by one Hg atom, which is further supported by theoretical calculations and experimental results as well. Importantly, differential pulse voltammetry (DPV) is first employed to estimate the highest occupied molecular orbit (HOMO) and the lowest unoccupied molecular orbit (LUMO) energies of Au24Hg1(PET)18 based on previous calculations.

HIF-1A and C/EBPs transcriptionally regulate adipogenic differentiation of bone marrow-derived MSCs in hypoxia.

INTRODUCTION: Bone marrow-derived mesenchymal stem cells (BMSCs, also known as bone marrow-derived mesenchymal stromal cells) are known to be a component of the tumor microenvironment. BMSCs are multipotent stromal cells that can differentiate into a variety of cell types, including osteocytes, chondrocytes, adipocytes, epithelial cells and endothelial cells. Stem cells found in niches or transplanted into injured tissues constantly encounter hypoxic stress. Areas with very low to no oxygen pressure exist in solid tumors. The differentiation capacity of BMSCs under hypoxic conditions remains controversial. METHODS: In this study, a hypoxic workstation, set at an oxygen concentration of 0.2% was used to mimic the hypoxic microenvironment of cancer in vivo. Oil red O staining and alkaline phosphatase staining were used to examine the adipogenic or osteogenic differentiation, respectively, of BMSCs. Real-time PCR was performed to explore the expression of adipocyte- or osteocyte-specific genes. An RT2 Profiler™ PCR Array was used to screen a panel of 84 genes associated with human adipogenesis in BMSCs under normal and hypoxic conditions. A dual-luciferase reporter assay and chromatin immunoprecipitation (ChIP) were applied to analyze promoter activity to evaluate the possible regulatory mechanism of adipocyte-specific gene expression. RESULTS: We found that this extreme hypoxia impaired osteogenic differentiation as indicated by the attenuation of alkaline phosphatase (ALP) activity and the reduced expression of osteogenic markers osteocalcin and osteopontin. Moreover, extreme hypoxia enhanced adipogenic differentiation, as indicated by the accumulation of lipid droplets and the expression of the adipocyte-specific genes leptin, LPL, CFD, PGAR and HIG2. In the extreme hypoxic conditions (0.2% oxygen), the overexpression of CCAAT enhancer-binding proteins (C/EBPs), especially C/EBPδ, and HIF-1A upregulated the promoter activities of adipocyte-specific genes such as leptin, CFD, HIG2, LPL, PGAR. In the present study, peroxisome proliferator-activated receptor-gamma (PPARγ) exerted a negative effect on the differentiation of BMSCs into adipocytes. CONCLUSIONS: In view of these findings, extreme hypoxia induced the adipogenic differentiation of BMSCs through HIF-1A and C/EBPs. These findings might provide clues regarding the roles of BMSCs in the cancer microenvironment.

Comment on "electrical-driven transport of endohedral fullerene encapsulating a single water molecule".

A Comment on the Letter by B. Xu and X. Chen, Phys. Rev. Lett. 110, 156103 (2013).

Density functional theory study of neutral and oxidized thiophene oligomers.

The effect of oxidation on the energetics and structure of thiophene (Th) oligomers is studied with density functional theory at the B3PW91∕6-311++G(d,p) level. Neutral n-Th oligomers (2 < n < 13) are gently curved planar chains. Ionization potential and electron affinity results show that n-Th oligomers are easier to be oxidized as their chain length increases. Oxidation states +2, +4, +6, and +8 are energetically stable in 12-Th. Upon oxidation the conjugated backbone of 12-Th switches from extended benzenoid phase to quinoid phase localized on groups of monomers regularly spaced along the chain. Oxidized states +2, +4, +6, and +8 of 12-Th display two +1e localized at the ends of their chains only because of the finite size of the chains. In 12-Th this end-effect extends over the two terminal monomers forming a positive-negative charge duet. This peculiar charge localization makes n-Th oligomers different from other conducting polymers with similar structure, such as polypyrrole. The spectrum of single-electron molecular states of oxidized 12-Th displays two localized single-electron states in the HOMO-LUMO energy gap per +2 oxidation state. Oligothiophene 12-Th doped with F atoms at 1:2 concentration presents a charge transfer of 3.4 e from oligomer to dopants that increases to 4.8 e in the presence of solvent. The charge distribution in these F-doped oligomers is similar to the +4 oxidation state of 12-Th. It is predicted that dopants produce an enhanced charge transfer localized in the proximity of their locations enhancing the formation of bipolarons in the central part of the oligomer chain.

Diffusion and desorption of oxygen atoms on graphene.

To understand the reversible oxidation of graphene in a recent experiment, a density-functional theory study is performed. The adsorption energy of isolated oxygen atom on graphene is 2.3 eV, indicating a strong interaction between them. However, the migration barrier of oxygen atoms on graphene is only 0.8 eV and oxygen diffusion is still possible. Provided with this possibility, we find that, although a single oxygen atom is very difficult to desorb, cooperative desorption of two oxygen atoms is feasible.

miR-18a promotes malignant progression by impairing microRNA biogenesis in nasopharyngeal carcinoma.

Dysregulation of microRNA (miRNA) biogenesis is implicated in cancer development and progression. Dicer and Drosha are established regulators of miRNA biogenesis. In this study, we used a miRNA array to evaluate the miRNA expression profiles in nasopharyngeal carcinoma (NPC) samples. The significance analysis of microarrays showed a global downregulation of miRNA expression in NPC samples compared with normal nasopharyngeal epithelial tissues. Notably, miR-18a, a member of the oncogenic miR-17-92 cluster, was upregulated in the NPC samples and cell lines. Clinical parameter studies showed that higher levels of miR-18a correlated with NPC advanced stage, lymph node metastasis, Epstein-Barr virus infection and a higher death rate from NPC, indicating oncogenic roles in NPC development. The expression levels of miR-18a and Dicer1 were inversely related in NPC tissues. Further studies demonstrated that miR-18a negatively regulated Dicer1 by binding to the 3' untranslated regions of Dicer1. In vitro and in vivo biological function assays showed that miR-18a promoted the growth, migration and invasion of NPC cells by regulating Dicer1 expression, which caused the global downregulation of miRNA expression levels including miR-200 family and miR-143. Furthermore, we found that the epithelial mesenchymal transition marker E-cadherin and the oncogene K-Ras were aberrantly expressed after miR-18a transduction, and these alterations were directly induced by downregulation of the miR-200 family and miR-143. Collectively, our findings indicate that miR-18a plays an oncogenic role in the development of NPC by widespread downregulation of the miRNome and could be a potential therapeutic target for NPC.