LncRNA PCGEM1 contributes to malignant behaviors of glioma by regulating miR-539-5p/CDK6 axis.

BACKGROUND: Glioma, one of the most prevalent and aggressive cancers, is regulated by long noncoding RNAs (lncRNAs). This study aims to research the functional mechanism of lncRNA PCGEM1 involved in glioma progression. METHODS: Expression levels of PCGEM1, miR-539-5p and CDK6 were analyzed by qRT-PCR in NHA, U251, U87, and LN229 cells or glioma tissues. shRNAs were used to knock down PCGEM1 in U251 and LN229 cells. Kaplan-Meier curve and log rank test were utilized to examine survival rate. CCK8 (Cell Counting Kit-8) assay, colony formation assay and EdU staining were conducted to detect cell proliferation. Transwell assay was performed to evaluate cell migration and invasion. Luciferase reporter assay was conducted to assess RNA interaction between PCGEM1 and miR-539-5p. Nude mice were used for tumor xenograft assay. RESULTS: LncRNA PCGEM1 was upregulated in glioma tissues and tumor cell lines. PCGEM1 upregulation predicted unsatisfactory prognosis. PCGEM1 knockdown inhibited proliferation, colony formation, migration and invasion. PCGEM1 knockdown delayed tumor growth in vivo. PCGEM1 played as a competing endogenous RNA (ceRNA) for miR-539-5p to promote CDK6 expression. MiR-539-5p mimics repressed glioma progression while CDK6 overexpression reversed the roles of PCGEM1 knockdown. CONCLUSION: PCGEM1 knockdown suppressed glioma progression through sponging miR-539-5p and regulating CDK6 expression, implying PCGEM1 as a potential therapeutic target.

Superconductivity in an organometallic compound.

Organometallic compounds constitute a very large group of substances that contain at least one metal-to-carbon bond in which the carbon is part of an organic group. They have played a major role in the development of the science of chemistry. These compounds are used to a large extent as catalysts (substances that increase the rate of reactions without themselves being consumed) and as intermediates in the laboratory and in industry. Recently, novel quantum phenomena such as topological insulators and superconductors were also suggested in these materials. However, there has been no report on the experimental exploration of the topological state. Evidence for superconductivity from the zero-resistivity state in any organometallic compound has not been achieved yet, though much effort has been made. Here we report the experimental realization of superconductivity with a critical temperature of 3.6 K in a potassium-doped organometallic compound, i.e. tri-o-tolylbismuthine, with evidence of both the Meissner effect and the zero-resistivity state through dc and ac magnetic susceptibility measurements. The obtained superconducting parameters classify this compound as a type-II superconductor. The benzene ring is identified to be the essential superconducting unit in such a phenyl organometallic compound. The superconducting phase and its composition are determined by combined studies of X-ray diffraction and theoretical calculations as well as Raman spectroscopy measurements. These findings enrich the applications of organometallic compounds in superconductivity and add a new electron-acceptor family of organic superconductors. This work also points to a large pool for finding superconductors from organometallic compounds.

Order-disorder transition in p-oligophenyls.

Poly(para-phenylene) has been recognized as one important family of conducting polymers upon doping with donors or acceptors. This system possesses a chain-like structure with infinite benzene rings linked with a single C-C bond. Oligophenyls as models of poly(para-phenylene) with short chains in the para position were found to exhibit superconductivity at transition temperatures ranging from 3 K to 123 K upon doping. Structural studies have revealed that there exist order-disorder transitions in many p-oligophenyls with almost doubled lattice constants in the b and c directions at low temperatures. Such a transition is of relevance to the understanding of the emergence of novel quantum functionality where unconventional polaronic interactions are relevant for the new emerging theory of superconductivity in this system. However, the accurate temperatures for the order-disorder transitions amongst these p-oligophenyls are still needed to be determined. The chain length effects on the order-disorder transitions in this system remain unknown. Here we report the systematic investigation of the evolution of the vibrational properties of the crystalline p-oligophenyls over a wide temperature range. The order-disorder transition is identified by three indicators, the lowest energy peak together with the intensity ratios between the 1280 cm-1 and 1220 cm-1 modes and between the two modes at around 1600 cm-1. A phase diagram of the order-disorder transition temperature and the melting curve for p-oligophenyls are thus established. The former is found to increase with the chain length and saturates at around 350 K for poly(para-phenylene).

Superconductivity and Phase Stability of Potassium-Intercalated p-Quaterphenyl.

To explore more novel superconductors, we have synthesized the potassium-doped p-quaterphenyl by an annealing or just a pestling process. The Meissner effect with critical temperatures ranging from 3.5 to 120 K is found by the magnetic susceptibility measurements in doped samples. The primary superconducting phase with a critical temperature of 7.2 K can be duplicated in the annealed and pestled samples. The charge transfer from metal to molecule is confirmed from the Raman scattering measurements. The X-ray diffraction analysis suggests that the low-temperature superconducting phase is due to the two-electron doping, whereas the high-temperature one corresponds to the high doping content. The occurrence of superconductivity in potassium-doped p-quaterphenyl supports the chain link organic molecules as promising candidates for high-temperature superconductors. This work also provides a simple method for synthesizing organic superconductors by pestling without annealing.

Superconductivity at 3.5 K and/or 7.2 K in potassium-doped triphenylbismuth.

We develop a two-step synthesis method-ultrasound treatment and low temperature annealing to explore superconductivity in potassium-doped triphenylbismuth, which is composed of one bismuth atom and three phenyl rings. The combination of dc and ac magnetic measurements reveals that one hundred percent of synthesized samples exhibit superconductivity at 3.5 K and/or 7.2 K at ambient pressure. The magnetization hysteresis loops provide a strong piece of evidence of type-II superconductors. It is found that the doped materials crystallize into the triclinic P1 structure, with a mole ratio of 4:1 between potassium and triphenylbismuth. Both the calculated electronic structure and measured Raman spectra indicate that superconductivity is realized by transferring electrons from the K-4s to C-2p orbital. Our study opens an encouraging window for the search of organic superconductors in organometallic molecules.

Superconductivity and phase stability of potassium-doped biphenyl.

Phenyl molecules are proposed as potential high-temperature superconductors due to exhibiting interesting properties. Here, we report the discovery of superconductivity with the critical temperature (Tc) of ∼7.2 Kelvin in potassium (K)-doped biphenyl (C12H10). The dc magnetic susceptibility measurements provide solid evidence for the presence of the Meissner effect in KxC12H10. The Raman spectra detected bipolaronic characteristics in this superconducting state, which are proposed to account for the electron pairing. Theoretical simulations provided the information of the crystal structure of KxC12H10. Combining XRD data with formation energy, we suggest that the superconducting phase corresponds to K2C12H10 or with a small charge fluctuation in a layered structure. The discovery of superconductivity in K-doped biphenyl vastly expands the potential applications in the superconducting field.

Vibrational Properties of p-Terphenyl.

Vibrational properties associated with the intra- and intermolecular terms of pristine p-terphenyl at low temperatures are analyzed in detail by Raman spectroscopy. Nearly all of the vibrational modes exhibit anomalous behaviors at the transition temperature of about 193 K on the frequencies, widths, and intensities. Meanwhile, the drastic drops of the spectrum weight result in the splits of many peaks like the lattice vibrational peaks and the peaks located at around 1220, 1280, and 1600 cm-1. All the anomalies result from the drastic decrease of the vibrational anharmonic coupling effects in the crystalline p-terphenyl after entering into the ordered state. The rapidly declining anharmonicity also makes contributions to the anomalous behaviors of the intensity ratios of the 1220, 1280, and 1600 cm-1 modes, as well as the energy separations between the combination bands and the fundamental bands. Our work is of great significance to understand the internal vibrational properties of p-terphenyl.

Synthesis, characterization, and study on HeLa cells activity of a dinuclear complex [Cu4(phen)4(H2O)2]·(pyri)·3H2O.

The complex [Cu4(phen)4(H2O)2]·(pyri)·3H2O(where phen=1,10-phenanthroline and pyri=3,5-pyridine dicarboxylic acid)has been synthesized and characterized. IR spectra, elemental analysis and X-ray single-crystal diffraction were carried out to determine the composition and crystal structure of the complex. The binding of the complex with HC-DNA (HeLa cells DNA, which was extracted by ourselves) was investigated by fluorescence spectrum. Gel electrophoresis assay demonstrates the ability of the complex to cleave the extracted HC-DNA. Additionally, the complex exhibited a significant cytotoxic specificity and cancer cell inhibitory rate. The apoptotic tests indicate that the complex have an apoptotic effect on HeLa cells.