Frequent methylation and oncogenic role of microRNA-34b/c in small-cell lung cancer

Small-cell lung cancer (SCLC) is an aggressive tumor with a dismal prognosis among primary lung cancers. MicroRNAs (miRNAs) can act as oncogenes or tumor-suppressor genes in human malignancy. The miR-34 family is comprised of tumor-suppressive miRNAs, and its reduced expression by methylation has been reported in various cancers, including non-small cell lung cancer (NSCLC). In this study, we investigated the alteration and tumor-suppressive impact of miR-34s in SCLC. The methylation of miR-34a and miR-34b/c was observed in 4 (36%) and 7 (64%) of 11 SCLC cell lines, respectively. Among the 27 SCLC clinical specimens, miR-34a and miR-34b/c were methylated in 4(15%) and 18 (67%), respectively. In contrast, 13 (28%) miR-34a methylated cases and 12 (26%) miR-34b/c methylated cases were found in 47 NSCLC primary tumors. The frequency of miR-34b/c methylation was significantly higher in SCLC than in NSCLC (p < 0.001). The expressions of miR-34s were reduced in methylated cell lines and tumors and restored after 5-aza-2'-deoxycytidine treatment, indicating that methylation was responsible for the reduced expression of miR-34s. Because the frequency of methylation was higher in miR-34b/c, we focused on miR-34b/c for a functional analysis. We examined the effect of miR-34b/c introduction on cell proliferation, migration and invasion. The transfection of miR-34b/c to two SCLC cell lines (H1048 and SBC5) resulted in the significant inhibition of cell growth, migration, and invasion, compared with control transfectants. Our results indicate that the aberrant methylation of miR-34b/c plays an important role in the pathogenesis of SCLC, implying that miR-34b/c may be a useful therapeutic target for SCLC

Microstructural transitions in resistive random access memory composed of molybdenum oxide with copper during switching cycles

The switching operation of a Cu/MoOx/TiN resistive random access memory (ReRAM) device was investigated using in situ transmission electron microscopy (TEM), where the TiN surface was slightly oxidized (ox-TiN). The relationship between the switching properties and the dynamics of the ReRAM microstructure was confirmed experimentally. The growth and/or shrinkage of the conductive filament (CF) can be classified into two set modes and two reset modes. These switching modes depend on the device's switching history, factors such as the amount of Cu inclusions in the MoOx layer and the CF geometry. High currents are needed to produce an observable change in the CF. However, sharp and stable switching behaviour can be achieved without requiring such a major change. The local region around the CF is thought to contribute to the ReRAM switching process

Vapor-Phase-Mediated Encapsulation of Guest Drug Molecules in the Hexagonal Columnar Form Structure of Polyethylene Glycol/γ-Cyclodextrin-Polypseudorotaxane

The drug/(PEG/γ-CD-PPRX) complex is a unique multicomponent supramolecular structure where the drug molecules are incorporated in the intermolecular spaces of the polypseudorotaxane (PPRX) prepared from polyethylene glycol (PEG) and γ-cyclodextrin (γ-CD). Herein, we report a sealed-heating preparation method to obtain an unanticipated polymorphic form of the drug/(PEG/γ-CD-PPRX) complex, which is the hexagonal-columnar (HC) form. The encapsulation efficiency of the six guest drugs was evaluated. The crystalline structural changes and the guest encapsulation monitored by powder X-ray diffraction revealed that a low sealed-heating temperature with a small amount of water was the optimal preparation condition for obtaining the HC form complex. The solution-state 1H nuclear magnetic resonance measurement demonstrated that stoichiometric complexation was dependent on the cross-sectional area of the guest drug molecule. However, stoichiometric complexation could not be achieved with all guest drugs, and the encapsulation efficiency was found to be governed by the guest drug properties, such as vapor pressure and molecular size. The findings of this study would contribute to understanding the complexation behavior of guest molecules in multicomponent supramolecular complexes and offer new insights into the fabrication of novel ordered supramolecular structures