Ethylene/polar monomer coordination copolymerization offers an attractive way of making functionalized polyolefins. However, ethylene copolymerization with industrially relevant short chain length ...alkenoic acid remain a big challenge. Here we report the efficient direct copolymerization of ethylene with vinyl acetic acid by tetranuclear nickel complexes. The protic monomer can be extended to acrylic acid, allylacetic acid, ω-alkenoic acid, allyl alcohol, and homoallyl alcohol. Based on X-ray analysis of precatalysts, control experiments, solvent-assisted electrospray ionization-mass spectrometry detection of key catalytic intermediates, and density functional theory studies, we propose a possible mechanistic scenario that involves a distinctive vinyl acetic acid enchainment enabled by Ni···Ni synergistic effects. Inspired by the mechanistic insights, binuclear nickel catalysts are designed and proved much more efficient for the copolymerization of ethylene with vinyl acetic acid or acrylic acid, achieving the highest turnover frequencies so far for both ethylene and polar monomers simultaneously.
Glioblastoma (GBM) is a prevalent and highly lethal form of glioma, with rapid tumor progression and frequent recurrence. Excessive outgrowth of pericytes in GBM governs the ecology of the ...perivascular niche, but their function in mediating chemoresistance has not been fully explored. Herein, we uncovered that pericytes potentiate DNA damage repair (DDR) in GBM cells residing in the perivascular niche, which induces temozolomide (TMZ) chemoresistance. We found that increased pericyte proportion correlates with accelerated tumor recurrence and worse prognosis. Genetic depletion of pericytes in GBM xenografts enhances TMZ-induced cytotoxicity and prolongs survival of tumor-bearing mice. Mechanistically, C-C motif chemokine ligand 5 (CCL5) secreted by pericytes activates C-C motif chemokine receptor 5 (CCR5) on GBM cells to enable DNA-dependent protein kinase catalytic subunit (DNA-PKcs)-mediated DDR upon TMZ treatment. Disrupting CCL5-CCR5 paracrine signaling through the brain-penetrable CCR5 antagonist maraviroc (MVC) potently inhibits pericyte-promoted DDR and effectively improves the chemotherapeutic efficacy of TMZ. GBM patient-derived xenografts with high CCL5 expression benefit from combined treatment with TMZ and MVC. Our study reveals the role of pericytes as an extrinsic stimulator potentiating DDR signaling in GBM cells and suggests that targeting CCL5-CCR5 signaling could be an effective therapeutic strategy to improve chemotherapeutic efficacy against GBM.
Characterizing the spatial distribution of precipitation across the Tibetan Plateau (TP) is important for understanding how the topography and atmospheric circulation influence the climatic patterns ...of the region. We collected 143 surface soil samples from the central and southeastern TP (SETP) for rock magnetic characterization of the spatial distribution of the pedogenic intensity. Comparison with meteorological data shows that pedogenic intensity decreases significantly along the pathway of moist air across the SETP toward the interior, and that there is a positive correlation between pedogenic magnetite/maghemite content and mean annual precipitation. By contrast, the samples from the central TP show a low degree of pedogenic alteration, consistent with the limited precipitation within this area. The results indicate the possibility of using magnetic properties of surface soils to determine the precipitation distribution in areas lacking meteorological stations. These observations, combined with published soil magnetic results, help to define the climatic boundary in the TP.
Plain Language Summary
Detailed information about the precipitation boundary across the Tibetan Plateau (TP) is lacking, which hinders our understanding of the dynamic relationships between precipitation distribution and atmospheric circulation patterns in this tectonically and climatically sensitive region. We used systematic environmental magnetic measurements of a large set of surface soil samples, combined with the analysis of a ∼70‐year meteorological data set to provide a comprehensive picture of the spatial distribution of precipitation in the TP and its adjacent areas. Additionally, a synthesis of all of the available magnetic data for surface samples clearly delineates the precipitation boundary between sub‐humid to semi‐arid and arid regions in the TP and its adjacent areas, providing important boundary conditions for regional climate modeling in the future.
Key Points
A critical altitudinal threshold of maximum mean annual precipitation is observed at 3,000–3,200 m a.s.l. in the southeastern Tibetan Plateau (TP)
Variations in magnetic properties of surface soils can be used to determine the precipitation distribution across the TP
A precipitation boundary between sub‐humid to semi‐arid and arid regions across the TP is defined
Postsynthetic metalation (PSM) has been employed as a robust method for the postsynthetic modification of metal–organic frameworks (MOFs). However, the lack of relevant information that can be ...obtained for the postsynthetically introduced metallic ions has hindered the development of PSM applications. Thanks to the advancement in single-crystal X-ray diffraction (SCXRD) technology, there have been a few recent examples in which successful postsynthetic introduction of single metal ions into MOFs occurred at the defined chelating sites. These works have provided useful explanations about the complicated host–guest chemistry involved in PSMs. On the other hand, there are only limited examples with crystallographic snapshots of the postsynthetic installation of metal clusters into the pores of MOFs using an ordinary SCXRD due to the loss of crystallinity of parent matrix during the PSM process. Herein, by the careful selection of starting materials and controlling the reaction conditions, we report the first crystallographic visualization of metal clusters inserted into Zr-based MOFs via PSM. The structural advantages of the parent Zr-MOF, which are inherited from the stable Zr6 cluster and triazole-containing dicarboxylate ligand, ensure both the preservation of high crystallinity and the presence of flexible coordination sites for PSM. Furthermore, PSM of metal clusters in a MOF pore space enhances stability of the final samples while also imparting the functionality of a successful catalyst toward ethylene dimerization reaction. The related construction ideas and structural information detailed in this work can help lay the foundation for further advancements using the postmodification of MOFs as well as open new doors for the utilization of SCXRD technology in the field of MOFs.
Orthodenticle homeobox 1 (OTX1) is a transcription factor that plays an important role in various human cancers. However, the function of OTX1 in laryngeal squamous cell carcinoma (LSCC) is largely ...unknown. We aimed to explore the roles of OTX1 in LSCC and its possible molecular mechanism.
The expression levels of OTX1 were assessed in LSCC cell lines and tissue samples. We further examined the effect of OTX1 on LSCC progression. The upstream regulator of OTX1 was identified using a computer algorithm and confirmed experimentally.
OTX1 was highly expressed in 70.7% (70/99) of LSCC tissue samples. The OTX1 expression in LSCC was significantly correlated with lymph node metastasis. High OTX1 expression in patients with LSCC was correlated with poor prognosis. Knockdown of OTX1 inhibited proliferation, colony formation, migration and invasion in LSCC cells. Knockdown of OTX1 inhibited tumor growth in a xenograft mouse model. Mechanistically, OTX1 might act as a direct target of miR-129-5p. OTX1 enhanced tumorigenicity and tumor growth both in vitro and in vivo.
Our findings support that OTX1 is an oncogene in LSCC tumorigenesis and progression. Furthermore, OTX1 is a direct target of miR-129-5p in LSCC cells. Taken together, OTX1 is a promising diagnostic and therapeutic marker for LSCC.
Long noncoding RNAs (lncRNAs) are related to different biological processes in non-small cell lung cancer (NSCLC). However, the possible molecular mechanisms underlying the effects of the long ...noncoding RNA HOXA11-AS (HOXA11 antisense RNA) in NSCLC are unknown.
HOXA11-AS was knocked down in the NSCLC A549 cell line and a high throughput microarray assay was applied to detect changes in the gene profiles of the A549 cells. Bioinformatics analyses (gene ontology (GO), pathway, Kyoto Encyclopedia of Genes and Genomes (KEGG), and network analyses) were performed to investigate the potential pathways and networks of the differentially expressed genes. The molecular signatures database (MSigDB) was used to display the expression profiles of these differentially expressed genes. Furthermore, the relationships between the HOXA11-AS, de-regulated genes and clinical NSCLC parameters were verified by using NSCLC patient information from The Cancer Genome Atlas (TCGA) database. In addition, the relationship between HOXA11-AS expression and clinical diagnostic value was analyzed by receiver operating characteristic (ROC) curve.
Among the differentially expressed genes, 277 and 80 genes were upregulated and downregulated in NSCLC, respectively (fold change ≥2.0, P < 0.05 and false discovery rate (FDR) < 0.05). According to the degree of the fold change, six upregulated and three downregulated genes were selected for further investigation. Only four genes (RSPO3, ADAMTS8, DMBT1, and DOCK8) were reported to be related with the development or progression of NSCLC based on a PubMed search. Among all possible pathways, three pathways (the PI3K-Akt, TGF-beta and Hippo signaling pathways) were the most likely to be involved in NSCLC development and progression. Furthermore, we found that HOXA11-AS was highly expressed in both lung adenocarcinoma and squamous cell carcinoma based on TCGA database. The ROC curve showed that the area under curve (AUC) of HOXA11-AS was 0.727 (95% CI 0.663-0.790) for lung adenocarcinoma and 0.933 (95% CI 0.906-0.960) for squamous cell carcinoma patients. Additionally, the original data from TCGA verified that ADAMTS8, DMBT1 and DOCK8 were downregulated in both lung adenocarcinoma and squamous cell carcinoma, whereas RSPO3 expression was upregulated in lung adenocarcinoma and downregulated in lung squamous cell carcinoma. For the other five genes (STMN2, SPINK6, TUSC3, LOC100128054, and C8orf22), we found that STMN2, TUSC3 and C8orf22 were upregulated in squamous cell carcinoma and that STMN2 and USC3 were upregulated in lung adenocarcinoma. Furthermore, we compared the correlation between HOXA11-AS and de-regulated genes in NSCLC based on TCGA. The results showed that the HOXA11-AS expression was negatively correlated with DOCK8 in squamous cell carcinoma (r = -0.124, P = 0.048) and lung adenocarcinoma (r = -0.176, P = 0.005). In addition, RSPO3, ADAMTS8 and DOCK8 were related to overall survival and disease-free survival (all P < 0.05) of lung adenocarcinoma patients in TCGA.
Our results showed that the gene profiles were significantly changed after HOXA11-AS knock-down in NSCLC cells. We speculated that HOXA11-AS may play an important role in NSCLC development and progression by regulating the expression of various pathways and genes, especially DOCK8 and TGF-beta pathway. However, the exact mechanism should be verified by functional experiments.
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