Signal transducer and activator of transcription 3 (STAT3) is a cytoplasmic transcription factor that regulates cell proliferation, differentiation, apoptosis, angiogenesis, inflammation and immune ...responses. Aberrant STAT3 activation triggers tumor progression through oncogenic gene expression in numerous human cancers, leading to promote tumor malignancy. On the contrary, STAT3 activation in immune cells cause elevation of immunosuppressive factors. Accumulating evidence suggests that the tumor microenvironment closely interacts with the STAT3 signaling pathway. So, targeting STAT3 may improve tumor progression, and anti-cancer immune response. In this review, we summarized the role of STAT3 in cancer and the tumor microenvironment, and present inhibitors of STAT3 signaling cascades. BMB Reports 2019; 52(7): 415-423.
A bent fluorenone-based dipyridyl ligand LA reacts with PdII cations to a solvent-dependent dynamic library of Pd n L2n assemblies, constituted by a Pd3LA 6 ring and a Pd4LA 8 tetrahedron as major ...components, and a Pd6LA 12 octahedron as minor component. Introduction of backbone steric hindrance in ligand LB allows exclusive formation of the Pd6LB 12 octahedron. Combining equimolar amounts of both ligands results in integrative self-sorting to give an unprecedented Pd4LA 4LB 4 heteroleptic tetrahedron. Key to the non-statistical assembly outcome is exploiting the structural peculiarity of the Pd4L8 tetrahedral topology, where the four lean ligands occupy two doubly bridged edges and the bulky ligands span the four remaining, singly bridged edges. Hence, the system finds a compromise between the entropic drive to form an assembly smaller than the octahedron and the enthalpic prohibition of pairing two bulky ligands on the same edge of the triangular ring. The emission of luminescent LA is maintained in both homoleptic Pd3LA 6 and heteroleptic Pd4LA 4LB 4.
The unique molecular balloon system of Pd6L8(NO3)12 (an inner cavity of 19 × 21 × 25 Å3 ⇄ 13 × 13 × 13 Å3) was carried out via the anion exchange of nitrate with alkyl sulfates.
While metal‐mediated self‐assembly is a popular technique to construct discrete nanosized objects, highly symmetric structures, built from one type of ligand at a time, are dominating reported ...systems. The tailored integration of a set of different ligands requires sophisticated approaches to avoid narcissistic separation or formation of statistical mixtures. Here, we demonstrate how the combination of three structure‐guiding effects (metal‐templated macrocyclization, additional bridging ligands and shape‐complementarity) based on Co(III)salphen metal nodes allows for a rational and high‐yielding synthesis of structurally complex, lantern‐shaped cages with up to four differentiable bridges. Three new heteroleptic coordination cages based on dinuclear Co(III)salphen macrocycles were synthesized in a one‐pot reaction approach and fully characterized, including single crystal X‐ray analyses. One cage groups two of the same ligands, another two different ligands around a symmetric Co2‐bis‐salphen ring. In the most complex structure, this ring is unsymmetric, rendering all four connections between the two metal centers distinguishable. While heteroleptic assembly around Pd(II) nodes has been shown to be dynamic, beneficial for cage‐to‐cage transformations, assembly cascades and adaptive systems, the herein introduced cages based on kinetically more inert Co(III)salphen will be advantageous for applications in enzyme‐like catalysis and molecular machinery that require enhanced structural and chemical stability.
Stable, low‐symmetry cages can be assembled by completing the octahedral coordination spheres of dinuclear Co(III)salphen macrocycles with shape‐complementary bis‐pyridyl bridges, starting from labile Co(II) precursors under aerobic conditions.
Systematic interconversion between trigonal prisms Pd3X6L2 (X− = Cl−, Br−, and I−) and cubic cages Pd6L812+(X−)12 (X− = BF4− and CF3SO3−) via anion exchange was established. Self-assembly of K2PdX4 ...(X− = Cl− and Br−) with a C3-symmetric tridentate 1,3,5-tris(2-isonicotinamidephenoxy)benzene (L) produces a trigonal prism, Pd3X6L2. Further photoreaction of the Pd3X6L2 (X− = Cl− and Br−) with CH2I2 gives rise to a halide-exchanged species, Pd3I6L2. In contrast, anion exchange of Pd3X6L2 (X− = Cl−, Br−, and I−) with BF4− yields cubic-shaped cages, Pd6L812+(BF4−)12, with an inner cavity of 15.9 × 15.9 × 15.9 Å3. Successive anion exchange of Pd6L812+(BF4−)12 with CF3SO3− gives rises to anion-exchanged Pd6L812+(CF3SO3−)12 and vice versa without cage destruction. Thus, the cage system is specifically sensitive to anions, enabling cage formation to recognize the binding affinity and size of various anions.
Self-assembly of M(ClO4)2 (M(ii) = Mn(ii), Co(ii), Ni(ii), Cu(ii), and Zn(ii)) with dicyclopentyldi(pyridine-3-yl)silane (L) as a donor in a mixture of acetonitrile and toluene produces crystals ...consisting of M6L12 double-stranded macrocycles. The geometry around the M(ii) cations is a typical octahedral arrangement, but the metallamacrocycles’ outer axial coordination environment is sensitive to the M(ii) cations. The conformation of the unique metallamacrocycles is informatively dependent on the nature of the coordination around the M(ii) cations via subtle co-ligand competition among perchlorate anions, water, and acetonitrile. Both the coordinated acetonitriles and the solvate molecules of the crystals are removed at 170 °C, thereby transforming the crystals into new crystals that return to their original form in the mixture of toluene and acetonitrile. Catalytic oxidation of 3,5-di-tert-butylcatechol using Cu6(ClO4)8(CH3CN)4L124ClO4·5C7H8 is much faster than those using the transformed product, Cu(ClO4)2L2, and a simple mixture of Cu(ClO4)2 + L.
Coordination polymers (CPs: Zn
L
3
n
(X)
2
n
,
L
=
trans
-1,4-bis(imidazolyl)-2-butene; X
−
= BF
4
−
, ClO
4
−
, NO
3
−
) allow for detection of the 4-nitrophenol (4-NP) oxidation process by ...enhanced electrochemical signals. Electrochemical measurement is a highly sensitive method providing much evidence of chemical reactions on an electrode surface. In the present study, we designed and synthesized, with reference to X-ray diffraction data and by spectroscopic analyses, new 3D coordination structures containing imidazolyl donors and zinc(
ii
). The presence of microcrystals Zn
L
3
n
(BF
4
)
2
n
on the working electrode enhanced the redox signals. Therefore, we propose a simple catalytic process that can explain these results and clarify the influence of anions that constitute CP materials used to improve electrochemical detection applications. The CP materials were characterized by nuclear magnetic resonance (NMR), infrared spectroscopy (IR), thermogravimetric (TG) analyses, single crystal X-ray diffraction (SC-XRD), and electrochemical analyses.
To investigate structural and anionic effects of coordination polymers (CPs) on electrochemical sensors, Zn-CPs were synthesized and used for 4-nitrophenol oxidation sensors.
Gravitational forces can impose physical stresses on the human body as it functions to maintain homeostasis. It has been reported that astronauts exposed to microgravity experience altered biological ...functions and many subsequent studies on the effects of microgravity have therefore been conducted. However, the anticancer mechanisms of simulated microgravity remain unclear. We previously showed that the proliferation of human Hodgkin's lymphoma (HL) cells was inhibited when these cells were cultured in time-averaged simulated microgravity (taSMG). In the present study, we investigated whether taSMG produced an anticancer effect. Exposure of human HL cells to taSMG for 2 days increased their reactive oxygen species (ROS) production and NADPH oxidase family gene expression, while mitochondrial mass, ATPase, ATP synthase, and intracellular ATP levels were decreased. Furthermore, human HL cells exposed to taSMG underwent autophagy via AMPK/Akt/mTOR and MAPK pathway modulation; such autophagy was inhibited by the ROS scavenger N-acetylcysteine (NAC). These results suggest an innovative therapeutic approach to HL that is markedly different from conventional chemotherapy and radiotherapy.
A practical porous crystalline matrix for molecular structure determination of a wide range of liquid chemicals has been set up. We herein report proof-of-concept research on the ...temperature-dependent single-crystal-to-single-crystal (SCSC) guest exchange of the P- and M-helix-enantiomeric multilayered ensemble with flexible open-channels of the shortest diameter, 4.4 × 4.4 Å2. This landmark ensemble is, to the best of our knowledge, the most efficient, practical, tolerant, and reproducible porous matrix for single crystal structure determination of general liquid compounds via easy SCSC guest exchange without any desolvation process. The innovative channel behaves in a guest-dependent flexible response manner and enables scientists to solve structures of a wide range of liquid chemicals. This paper reports the molecular structures of 41 liquid chemicals including chiral and natural compounds via guest exchange at >75% success rate.
The self‐assembly of ZnII ions with 1,3,5‐tris(isonicotinoyloxyethyl)cyanurate produces new topological (42⋅124)3(43)4 2D metal–organic frameworks (MOFs) with anion‐confining cages. The eclipsed ...assembly of each 2D MOF by π–π stacking of cyanurate moieties (3.352(5) Å) forms 3D MOFs consisting of nanochannels (10.5 Å). Two of the three anions are confined in each peanut‐type cage, resulting in hydrophobicity of the nanochannels. The hydrophobic nanochannel effectively adsorbs a wide range of fused aromatic hydrocarbons (FAHs) as monomers or dimers, rendering it potentially highly useful as an energy‐transfer material.
Slotted into place: The direct inclusion and organization of fused aromatic hydrocarbons (FAHs) within the hydrophobic 1D nanochannels of 3D metal–organic frameworks (MOFs) Zn3L4(CH3CN)6(X)6 (L=1,3,5‐tris(isonicotinoyloxyethyl)cyanurate; X−=BF4− and ClO4−) is reported. Förster resonance energy transfer (FRET) with the nanochannels from one FAH derivative to another is described.
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