10 research outputs found

    Hierarchical structures for example discourses.

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    <p>Hierarchical structures for example discourses.</p

    Copper-Promoted Aerobic Oxidative [3+2] Cycloaddition Reactions of N,N-Disubstituted Hydrazines with Alkynoates: Access to Substituted Pyrazoles

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    A copper-promoted aerobic oxidative [3+2] cycloaddition reaction for the synthesis of various substituted pyrazoles from N,N-disubstituted hydrazines with alkynoates in the presence of bases is developed. This work involves a direct C(sp3)ā€“H functionalization and the formation of new Cā€“C/Cā€“N bonds. In this strategy, inexpensive and easily available Cu2O serves as the promoter and air acts as the green oxidant. The reaction exhibits the advantages of high atom and step economy, high regioselectivity, and easy operation

    CCL21/CCR7 Axis Contributed to CD133<sup>+</sup> Pancreatic Cancer Stem-Like Cell Metastasis via EMT and Erk/NF-ĪŗB Pathway

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    <div><p>Background</p><p>Tumor metastasis is driven by malignant cells and stromal cell components of the tumor microenvironment. Cancer stem cells (CSCs) are thought to be responsible for metastasis by altering the tumor microenvironment. Epithelial-mesenchymal transition (EMT) processes contribute to specific stages of the metastatic cascade, promoted by cytokines and chemokines secreted by stromal cell components in the tumor microenvironment. C-C chemokine receptor 7 (CCR7) interacts with its ligand, chemokine ligand 21(CCL21), to mediate metastasis in some cancer cells lines. This study investigated the role of CCL21/CCR7 in promoting EMT and metastasis of cluster of differentiation 133<sup>+</sup> (CD133<sup>+</sup>) pancreatic cancer stem-like cells.</p><p>Methods</p><p>Panc-1, AsPC-1, and MIA PaCa-2 pancreatic cancer cells were selected because of their aggressive invasive potentials. CCR7 expression levels were examined in total, CD133<sup>+</sup> and CD133<sup>āˆ’</sup> cell fractions by Immunofluorescence analysis and real time-quantitative polymerase chain reaction (RT-qPCR). The role of CCL21/CCR7 in mediating metastasis and survival of CD133<sup>+</sup> pancreatic cancer stem-like cells was detected by Transwell assays and flow cytometry, respectively. EMT and lymph node metastasis related markers (E-cadherin, N- cadherin, LYVE-1) were analyzed by western blot. CCR7 expression levels were analyzed by immunohistochemical staining and RT-qPCR in resected tumor tissues, metastatic lymph nodes, normal lymph nodes and adjacent normal tissues from patients with pancreatic carcinoma.</p><p>Results</p><p>CCR7 expression was significantly increased in CD133<sup>+</sup> pancreatic cancer stem-like cells, resected pancreatic cancer tissues, and metastatic lymph nodes, compared with CD133<sup>āˆ’</sup> cancer cells, adjacent normal tissues and normal lymph nodes, respectively. CCL21/CCR7 promoted metastasis and survival of CD133<sup>+</sup> pancreatic cancer stem-like cells and regulated CD133<sup>+</sup> pancreatic cancer stem-like cells metastasis by modulating EMT and Erk/NF-ĪŗB pathway.</p><p>Conclusions</p><p>These results indicate a specific role for CCL21/CCR7 in promoting EMT and metastasis in CD133<sup>+</sup> pancreatic cancer stem-like cells. Furthermore the data also indicated the potential importance of developing therapeutic strategies targeting cancer stem-like cells and CCL21/CCR7 for reducing metastasis.</p></div

    Effect of CCL21/CCR7 on EMT in pancreatic cancer stem cells.

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    <p>(A) Expression of E-cad, N-cad, MMP-9, and LYVE-1 proteins in CD133<sup>+</sup> cells detected by western blot during treatment with CCL21(200 ng/mL), CCL21(200 ng/mL)+ siCCR7, siCCR7, and PBS. CD133<sup>+</sup> cells were transfected with non-targeted control siRNA and siRNA directed against CCR7. CCR7 levels were analyzed 48h after transfection by western blot. Data were normalized to Ī²-actin levels. Experiments were repeated three times with similar results. (B) Expression levels of Snail and Slug were measured by RT-qPCR after treatment of CD133<sup>+</sup> with CCL21 (200 ng/mL) or PBS. Data were normalized to Ī²-actin levels. Experiments were repeated three times and the data were expressed as meanĀ± SD. The difference between these two cell populations was significant (*P<0.05, **P<0.01, ***P<0.001).</p

    Expression levels of stemness related markers and CCR7 in CD133<sup>+</sup> pancreatic cancer stem-like cells.

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    <p>(A) Sorted CD133<sup>+</sup> cancer cells and the total cells were cultured in the serum-free DMEM-F12 medium for 72h. The percentage of CD133<sup>+</sup> in the total cell lines and sorted CD133<sup>+</sup> were tested by FACS. The results displayed that purity of the CD133<sup>+</sup> were 14.73% and 91.84%, respectively. (B) Oct-4, Sox-2, and CCR7 mRNA levels in total pancreatic cancer cells and in CD133<sup>+</sup> and CD133<sup>āˆ’</sup> cell fractions detected by RT-qPCR. Data were normalized to Ī²-actin levels. Experiments were repeated three times with similar results. (C) CCR7 expression levels in total pancreatic cancer cells and in CD133<sup>+</sup> and CD133<sup>āˆ’</sup> cell fractions were detected by immunofluorescence staining (200Ɨ),(*P<0.05, **P<0.01, ***P<0.001).</p

    CCL21/CCR7 expression was up-regulated in pancreatic carcinoma patients.

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    <p>(A) CCR7 mRNA expression levels in resected pancreatic cancer tissues, metastatic lymph nodes, normal lymph nodes and adjacent normal tissues were determined using RT-qPCR. Data were normalized to Ī²-actin expression. (B) CCR7 expression levels were detected in normal lymph nodes, adjacent normal tissues, resected pancreatic cancer tissues, and metastatic lymph nodes by immunohistochemistry(400Ɨ). All experiments were repeated three times (*P<0.05, **P<0.01, ***P<0.001). T, resected pancreatic cancer tissue; M, metastatic lymph node; N, adjacent normal tissue; L, normal lymph node.</p

    Effect of CCL21/CCR7 on survival of CD133<sup>+</sup> pancreatic cancer stem-like cells <i>in vitro</i>.

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    <p>(A) HBSS starvation induced CD133<sup>+</sup> apoptosis in a time-dependent manner. Cells were cultured in HBSS for 0, 12, 24, or 48 h followed by flow cytometry detection of phosphatidylserine exposure analyzed by Annexin V and propidium iodide (PI) staining. The apoptotic cells have been clearly increased in a time dependent manner. (B) Exogenous CCL21 protein promoted CD133<sup>+</sup> cell survival under HBSS conditions. Cells were treated for 48 h with different concentrations of CCL21 (a, 50ng/mL; b, 150ng/mL; c, 250 ng/mL), CCL21 (150 ng/mL)+ siCCR7(d), siCCR7(e), and PBS(f). Experiments were repeated three times and the data were expressed as meanĀ± SD. The difference between these two cell populations was significant (*P<0.05, **P<0.01, ***P<0.001).</p

    Effect of CCL21/CCR7 on Erk/NF-ĪŗB activation in pancreatic cancer stem cells.

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    <p>(A) Treatment of CD133<sup>+</sup> cells with CCL21 induced pErk1/2 and p65 activation in time-dependent manners. CD133<sup>+</sup> cells were treated with CCL21 (200 ng/mL) for different durations (0, 12, 24, or 48 h) and then harvested. Cell lysates were subjected to western blot analysis. Data were normalized to Ī²-actin levels. (B) Treatment of CD133<sup>+</sup> cells with an Erk1/2 inhibitor (U0126) inhibited cell migration compared with control group. Experiments were repeated three times and the data were expressed as meanĀ± SD. The difference between these two cell population was significant (*P<0.05, **P<0.01, ***P<0.001).</p

    van der Waals Epitaxial Growth of Atomically Thin Bi<sub>2</sub>Se<sub>3</sub> and Thickness-Dependent Topological Phase Transition

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    Two-dimensional (2D) atomic-layered heterostructures stacked by van der Waals interactions recently introduced new research fields, which revealed novel phenomena and provided promising applications for electronic, optical, and optoelectronic devices. In this study, we report the van der Waals epitaxial growth of high-quality atomically thin Bi<sub>2</sub>Se<sub>3</sub> on single crystalline hexagonal boron nitride (h-BN) by chemical vapor deposition. Although the in-plane lattice mismatch between Bi<sub>2</sub>Se<sub>3</sub> and h-BN is approximately 65%, our transmission electron microscopy analysis revealed that Bi<sub>2</sub>Se<sub>3</sub> single crystals epitaxially grew on h-BN with two commensurate states; that is, the (1Ģ…21Ģ…0) plane of Bi<sub>2</sub>Se<sub>3</sub> was preferably parallel to the (1Ģ…100) or (1Ģ…21Ģ…0) plane of h-BN. In the case of the Bi<sub>2</sub>Se<sub>3</sub> (2Ģ…110) āˆ„ h-BN (11Ģ…00) state, the MoireĢ pattern wavelength in the Bi<sub>2</sub>Se<sub>3</sub>/h-BN superlattice can reach 5.47 nm. These naturally formed thin crystals facilitated the direct assembly of h-BN/Bi<sub>2</sub>Se<sub>3</sub>/h-BN sandwiched heterostructures without introducing any impurity at the interfaces for electronic property characterization. Our quantum capacitance (QC) measurements showed a compelling phenomenon of thickness-dependent topological phase transition, which was attributed to the coupling effects of two surface states from Dirac Fermions at/or above six quintuple layers (QLs) to gapped Dirac Fermions below six QLs. Moreover, in ultrathin Bi<sub>2</sub>Se<sub>3</sub> (e.g., 3 QLs), we observed the midgap states induced by intrinsic defects at cryogenic temperatures. Our results demonstrated that QC measurements based on h-BN/Bi<sub>2</sub>Se<sub>3</sub>/h-BN sandwiched structures provided rich information regarding the density of states of Bi<sub>2</sub>Se<sub>3</sub>, such as quantum well states and Landau quantization. Our approach in fabricating h-BN/Bi<sub>2</sub>Se<sub>3</sub>/h-BN sandwiched device structures through the combination of bottomā€“up growth and topā€“down dry transferring techniques can be extended to other two-dimensional layered heterostructures
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