Overexpression of long non-coding RNA MEG3 suppresses breast cancer cell proliferation, invasion, and angiogenesis through AKT pathway.

Long non-coding RNA MEG3 has been identified as a tumor suppressor which plays important roles in tumorigenesis; however, its potential role in breast cancer has not been fully examined. Here, we showed that MEG3 was downregulated in breast cancer tissues and cell lines. Overexpression of MEG3 inhibited breast cancer cell proliferation and invasion, suggesting that MEG3 played an important role in breast cancer progression and metastasis. Moreover, MEG3 upregulation caused marked inhibition of angiogenesis-related factor expression. Conditioned medium derived from MEG3 overexpressed breast cancer cells significantly decreased the capillary tube formation of endothelial cells. Furthermore, elevated expression of MEG3 in breast cancer inhibits in vivo tumorigenesis and angiogenesis in a nude mouse xenograft model. Mechanistically, overexpression of MEG3 results in downregulation of AKT signaling, which is pivotal for breast cancer cell growth, invasion, and tumor angiogenesis. Collectively, these results suggest that MEG3 might suppress the tumor growth and angiogenesis via AKT signaling pathway and MEG3 may serve as a potential novel diagnostic and therapeutic target of breast cancer.

Effects of oxygen functional groups on the enhancement of the hydrogen spillover of Pd-doped activated carbon.

The hydrogen storage performance of Pd-doped oxidized activated carbon (Pd/AC-ox) with various oxygen contents or functional groups was investigated. The surface chemistry of the Pd/AC-ox sample was modified by treatment with hydrogen gas. Temperature-programmed desorption was performed to characterize the oxygen functional groups in each sample. In this study, low- and high-pressure hydrogen adsorption isotherm experiments were conducted using a static volumetric measurement at room temperature (RT) and pressures of up to 8 MPa. The results showed that increasing the oxygen content and functional groups on the surface of the Pd/AC-ox significantly improved the reversible RT hydrogen storage capacity due to the spillover effect. The hydrogen spillover enhancement factors at 0.12 MPa were greater than 100% for all samples. The hydrogen uptake of Pd/AC-ox1 at RT and 8 MPa with an oxygen content of 8.94 wt.% was 0.37 wt.%, which was 48% greater than that of Pd-free AC-ox (0.25 wt.%). In addition, the hydrogen uptake of Pd/AC-ox3 with lower oxygen contents demonstrates that the hydrogen spillover enhancement gradually disappears when the pressure is increased to more than 2 MPa (i.e., a transition from spillover to physisorption). The surface diffusion, or reversible adsorption, of the spiltover H atoms, which is enhanced by oxygen functional groups, was affected by a threshold amount of oxygen groups (such as hydroxyl groups).

Evidence for ambient-temperature reversible catalytic hydrogenation in Pt-doped carbons.

In situ high-pressure Raman spectroscopy, with corroborating density functional calculations, is used to probe C-H chemical bonds formed when dissociated hydrogen diffuses from a platinum nanocatalyst to three distinct graphenic surfaces. At ambient temperature, hydrogenation and dehydrogenation are reversible in the combined presence of an active catalyst and oxygen heteroatoms. Hydrogenation apparently occurs through surface diffusion in a chemisorbed state, while dehydrogenation requires diffusion of the chemisorbed species back to an active catalyst.

Nanostructure and hydrogen spillover of bridged metal-organic frameworks.

The metal-organic frameworks (MOF) with low and medium specific surface areas (SSA) were shown to be able to adsorb hydrogen via bridged spillover at room temperature (RT) up to an amount of full coverage of hydrogen in the MOF. Anomalous small-angle X-ray scattering was employed to investigate the key relationship between the structures and storage properties of the involved materials. It was found that the tunable imperfect lattice defects and the 3D pore network in the MOF crystal are the most critical structures for RT hydrogen uptake rather than the known micropores in the crystal, SSA, and Pt catalyst structure.

Characterization of pore structure in metal-organic framework by small-angle X-ray scattering.

MOF-5-like crystals were studied by small-angle X-ray scattering (SAXS) to reveal, both quantitatively and qualitatively, their real structural details, including pore surface characteristics, pore shape, size distribution, specific surface area (SSA), spatial distribution, and pore-network structure. A combined SAXS and wide-angle X-ray scattering (WAXS) experiment was conducted to investigate the variation of the pore structure with the MOF-5 crystalline phase produced at different cooling rates. The SSA of the MOF-5 crystals synthesized herein spanned a broad range from approximately 3100 to 800 m2/g. The real pore structures were divided into two regimes. In regime I the material consisted mainly of micropores of radius approximately 8 A as well as mesopores of radius 120 approximately 80 A. The structure in regime II was a fractal network of aggregated mesopores with radius >or=32 A as the monomer, reducing SSA and hydrogen uptake capacity at room temperature. The two regimes can be manipulated by controlling the synthesis parameters. The concurrent evolution of pore structure and crystalline phase during heating for solvent removal was also revealed by the in-situ SAXS/WAXS measurement. The understanding of the impact of the real pore structure on the properties is important to establish a favorable synthetic approach for markedly improving the hydrogen storage capacity of MOF-5.