Search

Anaplastic thyroid carcinoma (ATC) is resistant to standard therapies and has no effective treatment. Eukaryotic translation initiation factor 5A2 (EIF5A2) has shown to be upregulated in many malignant tumors and proposed to be a critical gene involved in tumor metastasis. In this study, we aimed to investigate the expression status of EIF5A2 in human ATC tissues and to study the role and mechanisms of EIF5A2 in ATC tumorigenesis in vitro and in vivo. Expression of EIF5A2 protein was analyzed in paraffin-embedded human ATC tissues and adjacent nontumorous tissues (ANCT) (n=24) by immunochemistry. Expressions of EIF5A2 mRNA and protein were analyzed in fresh-matched ATC and ANCT (n=23) and ATC cell lines by real-time polymerase chain reaction (PCR) and Western blotting. The effect of targeting EIF5A2 with short hairpin RNA (shRNA) or EIF5A2 overexpression on the ATC tumorigenesis and TGF-/Smad2/3 signals in vitro and in vivo was investigated. Expression of EIF5A2 was significantly upregulated in ATC tissues and cell lines compared with ANCT and normal follicular epithelial cell line. Functional studies found that targeting EIF5A2 induced SW1736 cell death in vitro and in vivo, followed by significantly downregulated phosphorylation of Smad2/3 (p-Smad2/3) in SW1736 cells at the protein level. Ectopic expression of EIF5A2 could promote 8505C cell growth in vitro and in vivo, followed by significantly upregulated p-Smad3 at the protein level. Recombinant human TGF-1 (hTGF-1) treatment decreased the antiproliferative activity of the EIF5A2 downexpressing 8505C cells through reversing pSmad2/3. Using the specific inhibitor SB431542 to block TGF- pathway or Smad3 siRNA to knock down Smad3 increased the antiproliferative activity of the EIF5A2-overexpressing 8505C cells through inhibiting pSmad2/3. Our findings indicated that EIF5A2 controled cell growth in ATC cells, and EIF5A/TGF-/Smad2/3 signal may be a potential therapeutic target for ATC treatment.

Numerous findings have demonstrated that MicroRNAs dysregulation plays a key role in many neoplasms, including oral squamous cell carcinoma (OSCC), yet the potential mechanisms of microRNAs in chemo-resistance remain elusive. Here, we analyzed the miR-132 expression in OSCC tissues and OSCC cell lines, and explored it role and mechanisms on invasion and migration and cisplatin (CDDP)-induced cell death. The clinical tissues of 37 patients with OSCCs and paired normal tissues were collected. The miR-132 expression in OSCC tissues and cell lines were detected by reverse transcription-quantitative polymerase chain reation (RT-qPCR). The in vitro repopulation models were established to mimic the biological processes of OSCC. The results showed that miR-132 expression was significantly decreased in the OSCC tissues and CDDP resistant OSCC cell line (CAL-27/CDDP). miR-132 mimic inhibited cell proliferation, invasion, migration and enhanced the pro-apoptotic ability of CDDP. On the contrary, downregulation of miR-132 promoted proliferation, invasion, migration and conferred OSCC cell resistance to CDDP-induced apoptosis in vitro. The TGF-β1 expression in OSCC tissues and CAL-27/CDDP cells was significantly higher. miR-132 significantly inhibited the TGF-β1/Smad2/3 signals. TGF-β1 upregulation significantly promoted OSCC cell proliferation and resumed OSCC cell chemo-resistance in the miR-132 overexpressing cells, which is contrary to the function of miR-132. In summary, miR-132 acts as a tumor suppressor and exerts a substantial role in inhibiting the proliferation, invasion, and enhanced the chemosensitivity to CDDP of OSCC via regulating TGF-β1/Smad2/3 signals in vitro. These observations indicate that miR-132 may be a suitable therapeutic target for the treatment of OSCC.

The purpose of this study was to better understand the impacts of dam-break on houses. Physical model experiments were undertaken to reproduce the process of flood water flowing around and through ...

Dike breaking is a disaster that could cause extensive damage. It could lead to flood flows outside the dike and induce water level fluctuations in the main channel. Numerical models are increasingly used to simulate flood flows due to dike-break, because direct observations from field surveys and physical models are rather limited. Existing knowledge concerning dam-break flows cannot be applied directly to dike-break flows because the effect of channel discharge cannot be neglected in the latter. In this study, physical experiments are done in a large laboratory flume to simulate the process of dike-break induced flood wave propagation in the floodplain and flow fluctuations in the main channel. The variations of water levels and velocities are measured and recorded using an array of pressure sensors and two acoustic Doppler velocimetry devices. A numerical model has been set up according to the experimental layout. The experiments have high repeatability and the numerical model predictions agree closely with the physical model data. The experimental results provide reliable information for improving the understanding of dike-break flow dynamics and for the verification of numerical models.

The crystal structure of a photocatalyst generally plays a pivotal role in its electronic structure and catalytic properties. In this work, we synthesized a series of La/Cr co-doped perovskite compounds ATiO3 (M = Ca, Sr and Ba) via a hydrothermal method. Their optical properties and photocatalytic activities were systematically explored from the viewpoint of their dependence on structural variations, i.e. impact of bond length and bond angles. Our results show that although La/Cr co-doping helps to improve the visible light absorption and photocatalytic activity of these wide band gap semiconductors, their light absorbance and catalytic performance are strongly governed by the Ti O bond length and Ti O Ti bond angle. A long Ti O bond and deviation of Ti O Ti bond angle away from 180° deteriorate the visible light absorption and photocatalytic activity. The best photocatalytic activity belongs to Sr0.9La0.1Ti0.9Cr0.1O3 with an average hydrogen production rate ∼2.88 μmol/h under visible light illumination (λ ≥ 400 nm), corresponding to apparent quantum efficiency ∼ 0.07%. This study highlights an effective way in tailoring the light absorption and photocatalytic properties of perovskite compounds by modifying cations in the A site.

Constituting solid solutions has been an appealing means to gain control over various physicochemical properties. In this work, we synthesized a series of SrTiO3-BiFeO3 solid solutions and systematically explored their structural, optical and photocatalytic properties. Our results show that all solid solutions crystallize in a primitive cubic structure and their band gap values can be easily tuned by adjusting molar ratios between SrTiO3 and BiFeO3. Photocatalytic hydrogen production under both full range and visible light irradiation is greatly improved after forming solid solutions. The highest hydrogen production rate obtained is ∼180 μmol/h under full range irradiation (λ ≥ 250 nm) and ∼4.2 μmol/h under visible light irradiation (λ ≥ 400 nm), corresponding to apparent quantum efficiency ∼2.28% and ∼0.10%, respectively. The activity is found to be strongly influenced by surface area and light absorption. Theoretical calculation suggests that Fe contributes to the formation of spin-polarized bands in the middle of original band gap and is responsible for the band gap reduction and visible light photocatalytic activity.

Constituting solid solutions for prototype perovskite compound SrTiO3 offers appealing means to tailor the optical and photocatalytic properties of this wide band gap semiconductor. Here we successfully synthesized a series of Sr1-xBixTi1-xFexO3 (0 ≤ x ≤ 0.5) solid solutions via hydrothermal method. Their crystal structures, surface nature and other physicochemical properties were systematically explored. Our results show that a large portion of BiFeO3 (up to 50%) can be incorporated into the structure SrTiO3 without symmetry degradation from cubic. A number of important factors such as microstructures, light absorbance and surface hydrophilicity are all strongly correlated with Bi/Fe content in the solid solutions. Photocatalytic performance was greatly improved after formation of solid solutions and high activity normally occurs in samples with large surface area, high crystallinity as well as absence of Bi (V) species. The highest activity belongs to sample Sr0.6Bi0.4Ti0.6Fe0.4O3 with photocatalytic hydrogen production rate ∼50 μmol/h under full range irradiation and ∼5 μmol/h under visible light irradiation, corresponding to apparent quantum efficiency ∼0.63% and 0.11%, respectively. Theoretical calculation reveals the critical role of Fe in constituting spin-polarized bands inside the intrinsic band gap of SrTiO3, therefore is responsible for band gap reduction and visible light activities. This work highlights the benefits of forming solid solutions in the design and development of efficient photocatalysts.

The crystal structure of photocatalysts generally plays a pivotal role in controlling their electronic structure as well as catalytic performance. In this work, a series of double perovskite compounds A2InTaO6 (A = Sr or Ba) and their Ni doped counterparts were investigated with the aim of understanding how doping and structural modification will affect their photocatalytic activity. Our results show that Ni doping is effective in improving the optical absorption of these wide band gap semiconductors and accommodating the Sr cation in the A sites leads to severe structural distortion, i.e. the In(Ni)-O-Ta bond angle deviates largely from 180°. A better photocatalytic performance was observed for samples with Ni doping and Ba in the A sites. The best photocatalytic hydrogen production rate recorded was ∼293.6 μmol h(-1) for Ba2In0.9Ni0.1TaO6 under full range irradiation, corresponding to an apparent quantum efficiency of 2.75%. DFT calculations reveal the role of Ni doping by forming additional spin-polarized bands inside the intrinsic band gap of the native perovskite. The better photocatalytic activity of Ba2In0.9Ni0.1TaO6 can then be understood as a result of a reduced band gap as well as a linear In(Ni)-O-Ta bond arrangement that is favorable for the strong metal-oxygen-metal interactions.