Long non-coding RNA NEAT1 promotes viability and migration of gastric cancer cell lines through up-regulation of microRNA-17.

OBJECTIVE: Gastric carcinoma (GC) is a common cancer with heavy mortality and poor outcome at advanced stages and metastasis. Long non-coding RNA nuclear-enriched abundant transcript 1 (NEAT1) has been reported to be an oncogene in GC recently. However, the underlying mechanism is far from understood. We aimed to explore the role of NEAT1 in GC as well as the underlying mechanisms. PATIENTS AND METHODS: The expression of NEAT1 in clinical human GC tissues and GC cell lines were assessed by quantitative reverse transcription PCR. Then, NEAT1 was non-physiologically expressed in GC cells (SGC-7901 and MKN45 cells), followed by estimation of cell viability, migration, invasion, apoptosis, activation of the phosphatidylinositol-3-kinase (PI3K)/AKT and glycogen synthase kinase 3ß (GSK3ß) pathways, and microRNA (miR)-17 level. Moreover, the effects of miR-17 inhibition on cell viability, migration, and activation of the PI3K/AKT and GSK3ß pathways in GC cells overexpressing NEAT1 were also explored. RESULTS: NEAT1 was up-regulated in GC tissues and cell lines. Then, cell viability and migration of GC cells were markedly increased by NEAT1 overexpression, while the cell invasion and apoptosis were unchanged. The phosphorylated level of PI3K, AKT, and GSK3ß were increased by NEAT1 overexpression. Subsequently, we found miR-17 level was positively correlated with NEAT1 expression, and NEAT1 functions through up-regulating miR-17. CONCLUSIONS: NEAT1 was up-regulated in GC tissues and cell lines. Its overexpression enhanced cell viability and migration through up-regulating miR-17, along with activation of the PI3K/AKT and GSK3ß pathways.

Stronger association of polycyclic aromatic hydrocarbons with soot than with char in soils and sediments.

The knowledge of the association of polycyclic aromatic hydrocarbons (PAHs) with organic matter and carbonaceous materials is critical for a better understanding of their environmental transport, fate, and toxicological effects. Extensive studies have been done with regard to the relationship of PAHs with total organic carbon (TOC) and elemental carbon (EC) in different environmental matrices. The relationship between PAHs and the two subtypes of EC, char (combustion residues) and soot (produced via gas-to-particle conversion) also has been tested in field and laboratory experiments using reference materials. However, a direct comparison of associations of PAHs between with char and with soot in real environmental matrices has to our knowledge not yet been reported because of a lack of methodology to differentiate them. In this study, char and soot were measured using the IMPROVE method to test their associations with 12 EPA priority PAHs measured in topsoil samples (N=22, top 10 cm) collected from the Guanzhong Plain and in surface sediment samples (N=32, top 5 cm) from the Wei River (central China). In both soils and sediments, ∑12PAHs were more strongly associated with soot than with char, mainly due to the fact that soot and PAHs were produced in the same gas phase during combustion, had a strong affinity for each other, and were transported and deposited together, while char, the combustion residue, was transported differently to PAHs due to its large particle size. Stronger correlations between PAHs and the different carbon fractions (TOC, soot, and char) in sediments than in soils were observed, which is associated with the redistribution of PAHs among the organic matter pools in water because of the processes during soil erosion and sedimentation in the river.

Comparison of elemental carbon in lake sediments measured by three different methods and 150-year pollution history in Eastern China.

Concentrations of elemental carbon (EC) were measured in a 150 yr sediment record collected from Lake Chaohu in Anhui Province, eastern China, using three different thermal analytical methods: IMPROVE_A thermal optical reflectance (TOR), STN_thermal optical transmittance (TOT), and chemothermal oxidation (CTO). Distribution patterns for EC concentrations are different among the three methods, most likely due to the operational definition of EC and different temperature treatments prescribed for each method. However, similar profiles were found for high-temperature EC fractions among different methods. Historical soot(TOR) (high-temperature EC fractions measured by the IMPROVE_A TOR method) from Lake Chaohu exhibited stable low concentrations prior to the late 1970s and a sharp increase thereafter, corresponding well with the rapid industrialization of China in the last three decades. This may suggest that high-temperature thermal protocols are suitable for differentiating between soot and other carbon fractions. A similar soot(TOR) record was also obtained from Lake Taihu (~200 km away), suggesting a regional source of soot. The ratio of char(TOR) (low-temperature EC fraction measured by the IMPROVE_A TOR method, after correction for pyrolysis) to soot(TOR) in Lake Chaohu shows an overall decreasing trend, consistent with gradual changes in fuel use from wood burning to increasing fossil fuel combustions. Average higher char(TOR)/soot(TOR) was observed in Lake Taihu than in Lake Chaohu in the past 150 years, consistent with the longer and more extensive industrialization around the Taihu region.