The oxidative kinetics of U-2 wt%Nb alloy with pearlitic structure at different stages (parabolic stage, transition stage, linear stage and decline stage) was uncovered using the oxygen-consumption ...and the reflectance spectroscopy method. Compared with U, the diffusive niobium enhances oxidative corrosion resistance of U-2 Nb at initial period. Unlike general cognition, the effect of niobium decreases with oxidative corrosion aggravating after initial period. It may result from mismatch of Nb-rich and Nb-deficient structure. The mechanism proposed in this work is propitious to the design of U-Nb binary alloys to improve their anti-corrosion property.
•The kinetics models of U‐2NbU-2 Nb alloy at different stage were established and the mechanism was also analyzed.•Nb enhances oxidative corrosion resistance of U-2 Nb at initial period. But the enhance of Nb weakens in following stages. U‐2NbU-2•The crackscaused by mismatch of Nb-rich and Nb-deficient structures, may result in attenuation of corrosion resistance.•Effect mechanism of Nb is analyzed, which is propitious to design of U-Nb binary alloys to improve anti-corrosion property.
BACKGROUND/AIMEvidence has indicated that fisetin induces cytotoxic effects in human cancer cell lines, including the inhibition of cell migration and invasion, however, the exact molecular mechanism ...of action of fisetin in human osteosarcoma cells remains unclear. MATERIALS AND METHODSThe anti-metastatic mechanisms of fisetin in human osteosarcoma U-2 OS cells were investigated in vitro. RESULTSFisetin reduced the viability of cells at different concentrations (2.5, 5 and 10 μM) as measured by flow cytometric assay. Fisetin suppressed cell mobility, migration and invasion of U-2 OS cells, as shown by wound healing assay and transwell filter chambers, respectively. The gelatin zymography assay showed that fisetin inhibited MMP-2 activity in U-2 OS cells. Results from western blotting indicated that fisetin reduced the levels of pEGFR, SOS-1, GRB2, Ras, PKC, p-ERK1/2, p-JNK, p-p-38, VEGF, FAK, RhoA, PI3K, p-AKT, NF-ĸB, uPA, MMP-7, MMP-9, and MMP-13, but increased GSK3β and E-cadherin in U-2 OS cells after 48 h of treatment. CONCLUSIONFisetin can be used in the future, as a target for the treatment of metastasis of human osteosarcoma cells.
Circadian clocks are endogenous oscillators essential for orchestrating daily rhythms in physiology, metabolism and behavior. While mouse models have been instrumental to elucidate the molecular ...mechanism of circadian rhythm generation, our knowledge about the molecular makeup of circadian oscillators in humans is still limited. Here, we used duplex CRISPR/Cas9 technology to generate three cellular models for studying human circadian clocks:
knockout cells,
knockout cells as well as
/
double knockout cells. Duplex CRISPR/Cas9 technology efficiently removed whole exons of
genes by using two guide RNAs targeting exon-flanking intron regions of human osteosarcoma cells (U-2 OS). Resulting cell clones did not express CRY proteins and showed short period, low-amplitude rhythms (for
knockout), long period rhythms (for
knockout) or were arrhythmic (for
/
double knockout) similar to circadian phenotypes of cells derived from classical knockout mouse models.
Background and purpose:
The human, rat, and mouse P2X
7
receptors have been previously characterized, and in this study we report the cloning and pharmacological properties of the guinea pig ...orthologue.
Experimental approach:
A cDNA encoding for the guinea pig P2X
7
receptor was isolated from a guinea pig brain library. The receptor was expressed in U‐2 OS cells using the BacMam viral expression system. A monoclonal antibody was used to confirm high levels of cell surface expression and the functional properties were determined in ethidium bromide accumulation studies.
Key results:
The predicted guinea pig protein is one amino acid shorter than the human and rat orthologues and over 70% identical to the rat and human receptors. In contrast to human and rat P2X
7
receptors, 2′‐&3′‐O‐(4benzoylbenzoyl)ATP (BzATP) was a partial agonist of the guinea pig P2X
7
receptor when compared to ATP and acted as an antagonist in some assays. However, as at other species orthologues, BzATP was more potent than ATP. The guinea pig P2X
7
receptor possessed higher affinity for 1‐N,O‐bis(5‐isoquinoline sulphonyl)‐N‐methyl‐L‐tyrosyl‐4‐phenylpiperazine (KN62), suramin and Coomassie Brilliant Blue than human or rat P2X
7
receptors suggesting that it is pharmacologically different to other rodent or human P2X
7
receptors.
Conclusions and implications:
The guinea pig recombinant P2X
7
receptor displays a number of unique properties that differentiate it from the human, rat and mouse orthologues and this structural and functional information should aid in our understanding of the interaction of agonists and antagonist with the P2X
7
receptor.
British Journal of Pharmacology
(2008)
153
, 544–556; doi:
10.1038/sj.bjp.0707596
; published online 26 November 2007
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•The nanopatterning technique of PES, PEI and PEEK with KrF laser was described.•Both nanodots and ripples on aromatic polymers were successfully constructed.•Dimensions of ...nanostructures can be precisely controlled.•Surface parameters dependent on angle of laser beam incidence were characterized.•U-2 OS cell adaptation and growth on nanopatterned surface was described.
In this work, we describe ripple and dot nanopatterning of three different aromatic polymer substrates by KrF excimer laser treatment. The conditions for regular structures were established by laser fluence and number of pulses. Subsequently, the influence of the angle of incidence of a laser beam was investigated. We have chosen polyethersulfone (PES), polyetherimide (PEI) and polyetheretherketone (PEEK) as substrates for modification since they are thermally, chemically and mechanically resistant aromatic polymers with high absorption coefficients at excimer laser wavelength. As a tool of wettability investigation, we used contact angle measurement and for determination of the absorption edge, UV–vis spectroscopy was used. Material surface chemistry was analyzed using FTIR and the changes caused by modification were gained as differential spectra by subtraction of the spectra of non-modified material. Surface morphology was investigated by atomic force microscopy, also the roughness and surface area of modified samples were studied. The scans showed the formation of regular periodic structures, ripples and dots, after treatment by 8 and 16mJcm−2 and 6000 pulses. Further, initial in vitro cytocompatibility tests were performed using U-2 OS cell line growing on PES samples subjected to scanning electron microscopy analysis. The structure formation mapping contributes strongly to development of new applications using nanostructured polymers, e.g. in tissue engineering or in combination with metallization in selected electronics and metamaterials construction.
Osteosarcoma (OS) is a life-threatening malignant bone tumor associated with poor prognosis among children. The survival rate of the patient is still arguably low even with intensive treatment ...provided, plus with the inherent side effects from the chemotherapy, which gives more unfavorable outcomes. Hence, the search for potent anti-osteosarcoma agent with promising safety profile is still on going. Natural occurring substance like curcumin has gained a lot of attention due to its splendid safety profile as well as it pharmacological advantages such as anti-metastasis and anti-angiogenesis. However, natural curcumin was widely known for its poor cellular uptake, which undermines all potential that it possesses. This prompted the development of synthetically synthesized curcuminoid analog, known as (Z)-3-hydroxy-1-(2-hydroxyphenyl)-3-phenylprop-2- en-1-one (DK1). In this present study, in vitro scratch assay, transwell migration/invasion assay, HUVEC tube formation assay, and ex vivo rat aortic ring assays were performed in order to investigate the anti-metastatic and anti-angiogenic potential of DK1. For further comprehension of DK1 mechanism on human osteosarcoma cell lines, microarray gene expression analysis, quantitative polymerase chain reaction (qPCR), and proteome profiler were adopted, providing valuable forecast from the expression of important genes and proteins related to metastasis and angiogenesis. Based on the data gathered from the bioassays, DK1 was able to inhibit the metastasis and angiogenesis of human osteosarcoma cell lines by significantly reducing the cell motility, number of migrated and invaded cells as well as the tube formation and micro-vessels sprouting. Additionally, DK1 also has significantly regulated several cancer pathways involved in OS proliferation, metastasis, and angiogenesis such as PI3K/Akt and NF-κB in both U-2 OS and MG-63. Regulation of PI3K/Akt caused up-regulation of genes related to metastasis inhibition, namely, PTEN, FOXO, PLK3, and GADD45A. Meanwhile, NF-κB pathway was regulated by mitigating the expression of NF-κB activator such as IKBKB and IKBKE in MG-63, whilst up-regulating the expression of NF-κB inhibitors such as NFKBIA and NFKBIE in U-2 OS. Finally, DK1 also has successfully hindered the metastatic and angiogenic capability of OS cell lines by down-regulating the expression of pro-metastatic genes and proteins like MMP3, COL11A1, FGF1, Endoglin, uPA, and IGFBP2 in U-2 OS. Whilst for MG-63, the significantly down-regulated oncogenes were Serpin E1, AKT2, VEGF, uPA, PD-ECGF, and Endoglin. These results suggest that curcumin analog DK1 may serve as a potential new anti-osteosarcoma agent due to its anti-metastatic and anti-angiogenic attributes.
Lupeol, one of the common components from the fruits and natural foods, has been reported to exert antitumor activities in many human cancer cell lines; however, its effects on osteosarcoma cell ...metastasis were not elucidated. In the present study, lupeol at 10-25 μM induced cell morphological changes and decreased total viable cell number in U-2 OS cells. Lupeol (5-15 μM) suppressed cell mobility, migration, and invasion by wound healing and transwell chamber assays, respectively. Lupeol inhibited the activities of MMP-2 and -9 in U-2 OS cells by gelatin zymography assay. Lupeol significantly decreased PI3K, pAKT, β-catenin, and increased GSK3β. Furthermore, lupeol decreased the expressions of Ras, p-Raf-1, p-p38, and β-catenin. Lupeol also decreased uPA, MMP-2, MMP-9, and N-cadherin but increased VE-cadherin in U-2 OS cells. Based on these observations, we suggest that lupeol can be used in anti-metastasis of human osteosarcoma cells in the future.
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