Transcription factor LHX9 (LIM Homeobox 9) enhances pyruvate kinase PKM2 activity to induce glycolytic metabolic reprogramming in cancer stem cells, promoting gastric cancer progression.

BACKGROUND: Glycolytic metabolic reprogramming is a phenomenon in which cells undergo altered metabolic patterns during malignant transformation, mainly involving various aspects of glycolysis, electron transport chain, oxidative phosphorylation, and pentose phosphate pathway. This reprogramming phenomenon can be used as one of the markers of tumorigenesis and development. Pyruvate kinase is the third rate-limiting enzyme in the sugar metabolism process by specifically catalyzing the irreversible conversion of PEP to pyruvate. PURPOSE: This study aimed to reveal the critical mediator(s) that regulate glycolytic metabolism reprogramming in gastric cancer and their underlying molecular mechanism and then explore the molecular mechanisms by which LHX9 may be involved in regulating gastric cancer (GC) progression. METHODS: Firstly, we downloaded the GC and glycolysis-related microarray datasets from TCGA and MSigDB databases and took the intersection to screen out the transcription factor LHX9 that regulates GC glycolytic metabolic reprogramming. Software packages were used for differential analysis, single gene predictive analysis, and Venn diagram. In addition, an enrichment analysis of the glycolytic pathway was performed. Immunohistochemical staining was performed for LHX9 and PKM2 protein expression in 90 GC patients, and the association between their expressions was evaluated by Spearman's correlation coefficient method. Three human GC cell lines (AGS, NCI-N87, HGC-27) were selected for in vitro experimental validation. Flow cytometry was utilized to determine the stem cell marker CD44 expression status in GCSCs. A sphere formation assay was performed to evaluate the sphere-forming capabilities of GCSCs. In addition, RT-qPCR and Western blot experiments were employed to investigate the tumor stem cell markers OCT4 and SOX2 expression levels in GCSCs. Furthermore, a lentiviral expression vector was constructed to assess the impact of downregulating LHX9 or PKM2 on the glycolytic metabolic reprogramming of GCSCs. The proliferation, migration, and invasion of GCSCs were then detected by CCK-8, EdU, and Transwell assays. Subsequently, the mutual binding of LHX9 and PKM2 was verified using chromatin immunoprecipitation and dual luciferase reporter genes. In vivo experiments were verified by establishing a subcutaneous transplantation tumor model in nude mice, observing the size and volume of tumors in vivo in nude mice, and obtaining fresh tissues for subsequent experiments. RESULTS: Bioinformatics analysis revealed that LHX9 might be involved in the occurrence and development of GC through regulating glycolytic metabolism. High LHX9 expression could be used as a reference marker for prognosis prediction of GC patients. Clinical tissue assays revealed that LHX9 and PKM2 were highly expressed in GC tissues. Meanwhile, GC tissues also highly expressed glycolysis-associated protein GLUT1 and tumor cell stemness marker CD44. In vitro cellular assays showed that LHX9 could enhance its activity and induce glycolytic metabolic reprogramming in GCSCs through direct binding to PKM2. In addition, the knockdown of LHX9 inhibited PKM2 activity and glycolytic metabolic reprogramming and suppressed the proliferation, migration, and invasive ability of GCSCs. In vivo animal experiments further confirmed that the knockdown of LHX9 could reduce the tumorigenic ability of GCSCs in nude mice by inhibiting PKM2 activity and glycolytic metabolic reprogramming. CONCLUSION: The findings suggest that both LHX9 and PKM2 are highly expressed in GCs, and LHX9 may induce the reprogramming of glycolytic metabolism through transcriptional activation of PKM2, enhancing the malignant biological properties of GCSCs and ultimately promoting GC progression.

The regulatory role of cancer stem cell marker gene CXCR4 in the growth and metastasis of gastric cancer.

Single-cell RNA sequencing (scRNA-seq) and bulk RNA sequencing (bulk RNA-seq) are increasingly used for screening genes involved in carcinogenesis due to their capacity for dissecting cellular heterogeneity. This study aims to reveal the molecular mechanism of the cancer stem cells (CSCs) marker gene CXCR4 in gastric cancer (GC) growth and metastasis through scRNA-seq combined with bulk RNA-seq. GC-related scRNA-seq data were downloaded from the GEO database, followed by UMAP cluster analysis. Non-malignant cells were excluded by the K-means algorithm. Bulk RNA-seq data and clinical sample information were downloaded from the UCSC Xena database. GO and KEGG pathway analyses validated the correlation between genes and pathways. In vitro and in vivo functional assays were used to examine the effect of perturbed CXCR4 on malignant phenotypes, tumorigenesis, and liver metastasis. A large number of highly variable genes were identified in GC tissue samples. The top 20 principal components were selected, and the cells were clustered into 6 cell types. The C4 cell cluster from malignant epithelial cells might be CSCs. CXCR4 was singled out as a marker gene of CSCs. GC patients with high CXCR4 expression had poor survival. Knockdown of CXCR4 inhibited the malignant phenotypes of CSCs in vitro and curtailed tumorigenesis and liver metastasis in nude mice. CSC marker gene CXCR4 may be a key gene facilitating malignant phenotypes of CSCs, which thus promotes tumor growth and liver metastasis of GC.

LncRNA H19-rich extracellular vesicles derived from gastric cancer stem cells facilitate tumorigenicity and metastasis via mediating intratumor communication network.

BACKGROUND: Extracellular vesicles (EVs) transport biologically active molecules, and represent a recently identified way of intercellular communication. Recent evidence has also reported that EVs shed by cancer stem cells (CSCs) make a significant contribution to carcinogenesis and metastasis. Here, this study aims to explore the possible molecular mechanism of CSCs-EVs in gastric cancer (GC) by mediating intratumor communication network. METHODS: CSCs and non-stem cancer cells (NSCCs) were sorted from GC cells, and EVs were isolated from CSCs. H19 was knocked down in CSCs, and CSCs-EVs or CSCs-EVs containing shRNA-H19 (CSCs-EVs-sh-H19) were co-cultured with NSCCs, followed by evaluation of the malignant behaviors and stemness of NSCCs. Mouse models of GC were established and injected with CSCs-EVs from sh-H19-treated NSCCs in vivo. RESULTS: CSCs had notable self-renewal and tumorigenic capacity compared with NSCCs. CSCs promoted the malignant behaviors of NSCCs and expression of stemness marker proteins through secretion of EVs. Inhibited secretion of CSCs-EVs curtailed the tumorigenicity and metastasis of NSCCs in vivo. H19 could be delivered by CSCs-EVs into NSCCs. H19 promoted the malignant behaviors of NSCCs and stemness marker protein expression in vitro along with tumorigenicity and liver metastasis in vivo, which was mechanistically associated with activation of the YAP/CDX2 signaling axis. CONCLUSION: Taken together, the present study points to the importance of a novel regulatory axis H19/YAP/CDX2 in carcinogenic and metastatic potential of CSCs-EVs in GC, which may be potential targets for anticancer therapy.

Squid Skin Cell-Inspired Refractive Index Mapping of Cells, Vesicles, and Nanostructures.

The fascination with the optical properties of naturally occurring systems has been driven in part by nature's ability to produce a diverse palette of vibrant colors from a relatively small number of common structural motifs. Within this context, some cephalopod species have evolved skin cells called iridophores and leucophores whose constituent ultrastructures reflect light in different ways but are composed of the same high refractive index material─a protein called reflectin. Although such natural optical systems have attracted much research interest, measuring the refractive indices of biomaterial-based structures across multiple different environments and establishing theoretical frameworks for accurately describing the obtained refractive index values has proven challenging. Herein, we employ a synergistic combination of experimental and computational methodologies to systematically map the three-dimensional refractive index distributions of model self-assembled reflectin-based structures both in vivo and in vitro. When considered together, our findings may improve understanding of squid skin cell functionality, augment existing methods for characterizing protein-based optical materials, and expand the utility of emerging holotomographic microscopy techniques.

Disproportionation of Nitric Oxide at a Surface-Bound Nickel Porphyrinoid.

Uncommon metal oxidation states in porphyrinoid cofactors are responsible for the activity of many enzymes. The F430 and P450nor co-factors, with their reduced NiI - and FeIII -containing tetrapyrrolic cores, are prototypical examples of biological systems involved in methane formation and in the reduction of nitric oxide, respectively. Herein, using a comprehensive range of experimental and theoretical methods, we raise evidence that nickel tetraphenyl porphyrins deposited in vacuo on a copper surface are reactive towards nitric oxide disproportionation at room temperature. The interpretation of the measurements is far from being straightforward due to the high reactivity of the different nitrogen oxides species (eventually present in the residual gas background) and of the possible reaction intermediates. The picture is detailed in order to disentangle the challenging complexity of the system, where even a small fraction of contamination can change the scenario.

Disproportionation of Nitric Oxide at a Surface-Bound Nickel Porphyrinoid.

Uncommon metal oxidation states in porphyrinoid cofactors are responsible for the activity of many enzymes. The F430 and P450nor co-factors, with their reduced NiI- and FeIII-containing tetrapyrrolic cores, are prototypical examples of biological systems involved in methane formation and in the reduction of nitric oxide, respectively. Herein, using a comprehensive range of experimental and theoretical methods, we raise evidence that nickel tetraphenyl porphyrins deposited in vacuo on a copper surface are reactive towards nitric oxide disproportionation at room temperature. The interpretation of the measurements is far from being straightforward due to the high reactivity of the different nitrogen oxides species (eventually present in the residual gas background) and of the possible reaction intermediates. The picture is detailed in order to disentangle the challenging complexity of the system, where even a small fraction of contamination can change the scenario.

Reconfigurable Micro- and Nano-Structured Camouflage Surfaces Inspired by Cephalopods.

Wrinkled surfaces and materials are found throughout the natural world in various plants and animals and are known to improve the performance of emerging optical and electrical technologies. Despite much progress, the reversible post-fabrication tuning of wrinkle sizes and geometries across multiple length scales has remained relatively challenging for some materials, and the development of comprehensive structure-function relationships for optically active wrinkled surfaces has often proven difficult. Herein, by drawing inspiration from natural cephalopod skin and leveraging methodologies established for artificial adaptive infrared platforms, we engineer systems with hierarchically reconfigurable wrinkled surface morphologies and dynamically tunable visible-to-infrared spectroscopic properties. Specifically, we demonstrate architectures for which mechanical actuation changes the surface morphological characteristics; modulates the reflectance, transmittance, and absorptance across a broad spectral window; controls the specular-to-diffuse reflectance ratios; and alters the visible and thermal appearances. Moreover, we demonstrate the incorporation of these architectures into analogous electrically actuated appearance-changing devices that feature competitive figures of merit, such as reasonable maximum areal strains, rapid response times, and good stabilities upon repeated actuation. Overall, our findings constitute another step forward in the continued development of cephalopod-inspired light- and heat-manipulating systems and may facilitate advanced applications in the areas of sensing, electronics, optics, soft robotics, and thermal management.

Structure, self-assembly, and properties of a truncated reflectin variant.

Naturally occurring and recombinant protein-based materials are frequently employed for the study of fundamental biological processes and are often leveraged for applications in areas as diverse as electronics, optics, bioengineering, medicine, and even fashion. Within this context, unique structural proteins known as reflectins have recently attracted substantial attention due to their key roles in the fascinating color-changing capabilities of cephalopods and their technological potential as biophotonic and bioelectronic materials. However, progress toward understanding reflectins has been hindered by their atypical aromatic and charged residue-enriched sequences, extreme sensitivities to subtle changes in environmental conditions, and well-known propensities for aggregation. Herein, we elucidate the structure of a reflectin variant at the molecular level, demonstrate a straightforward mechanical agitation-based methodology for controlling this variant's hierarchical assembly, and establish a direct correlation between the protein's structural characteristics and intrinsic optical properties. Altogether, our findings address multiple challenges associated with the development of reflectins as materials, furnish molecular-level insight into the mechanistic underpinnings of cephalopod skin cells' color-changing functionalities, and may inform new research directions across biochemistry, cellular biology, bioengineering, and optics.

A dynamic thermoregulatory material inspired by squid skin.

Effective thermal management is critical for the operation of many modern technologies, such as electronic circuits, smart clothing, and building environment control systems. By leveraging the static infrared-reflecting design of the space blanket and drawing inspiration from the dynamic color-changing ability of squid skin, we have developed a composite material with tunable thermoregulatory properties. Our material demonstrates an on/off switching ratio of ~25 for the transmittance, regulates a heat flux of ~36 W/m2 with an estimated mechanical power input of ~3 W/m2, and features a dynamic environmental setpoint temperature window of ~8 °C. Moreover, the composite can manage one fourth of the metabolic heat flux expected for a sedentary individual and can also modulate localized changes in a wearer's body temperature by nearly 10-fold. Due to such functionality and associated figures of merit, our material may substantially reduce building energy consumption upon widespread deployment and adoption.

On-surface trapping of alkali atoms by crown ethers in ultra high vacuum.

Crown ethers, assembled into a regular 2D array via a chemical guest-host recognition process, have been successfully employed to trap sodium atoms on a surface, under ultra-high vacuum conditions.

Substrate- to Laterally-Driven Self-Assembly Steered by Cu Nanoclusters: The Case of FePcs on an Ultrathin Alumina Film.

We show that, for the formation of a metallorganic monolayer, it is possible to artificially divert from substrate- to laterally-driven self-assembly mechanisms by properly tailoring the corrugation of the potential energy surface of the growth template. By exploiting the capability of an ultrathin alumina film to host metallic nanoparticle seeds, we tune the symmetry of a iron phthalocyanine (FePc) two-dimensional crystal, thus showing that it is possible to switch from trans to lateral dominating interactions in the controlled growth of an organic/inorganic heterostack. Finally, by selecting the size of the metallic clusters, we can also control the FePc-metal interaction strength.

Growth of regular nanometric molecular arrays on a functional 2D template based on a chemical guest-host approach.

A regular 2D array of crown molecules, which would spontaneously self-assemble into disordered molecular clusters, is obtained by exploiting a guest-host process, based on the chemical affinity between amino and carboxylic groups on a gold surface. First a carboxylic organic template is formed, which then serves as a host for amino-functionalized crown molecules. The amino-carboxylic interaction thereby drives the formation of a monolayer of guest molecules, regularly distributed at the nanometer scale, preventing their aggregation in unordered clusters observed on a bare gold surface. This method, which can be applied to other guest molecules, represents a novel route to overcome the shape-matching requirements of the standard guest-host architectures. Furthermore, it is intrinsically selective, due to the chemical nature of the anchoring process.

Publisher Correction: Multi-orbital charge transfer at highly oriented organic/metal interfaces.

The original version of this Article contained an error in the spelling of the author Claus Michael Schneider, which was incorrectly given as Claus Michael Schneidery. This has now been corrected in both the PDF and HTML versions of the Article.

Multi-orbital charge transfer at highly oriented organic/metal interfaces.

The molecule-substrate interaction plays a key role in charge injection organic-based devices. Charge transfer at molecule-metal interfaces strongly affects the overall physical and magnetic properties of the system, and ultimately the device performance. Here, we report theoretical and experimental evidence of a pronounced charge transfer involving nickel tetraphenyl porphyrin molecules adsorbed on Cu(100). The exceptional charge transfer leads to filling of the higher unoccupied orbitals up to LUMO+3. As a consequence of this strong interaction with the substrate, the porphyrin's macrocycle sits very close to the surface, forcing the phenyl ligands to bend upwards. Due to this adsorption configuration, scanning tunneling microscopy cannot reliably probe the states related to the macrocycle. We demonstrate that photoemission tomography can instead access the Ni-TPP macrocycle electronic states and determine the reordering and filling of the LUMOs upon adsorption, thereby confirming the remarkable charge transfer predicted by density functional theory calculations.Charge transfer at molecule-metal interfaces affects the overall physical and magnetic properties of organic-based devices, and ultimately their performance. Here, the authors report evidence of a pronounced charge transfer involving nickel tetraphenyl porphyrin molecules adsorbed on copper.

Electronic properties of the boroxine-gold interface: evidence of ultra-fast charge delocalization.

We performed a combined experimental and theoretical study of the assembly of phenylboronic acid on the Au(111) surface, which is found to lead to the formation of triphenylboroxines by spontaneous condensation of trimers of molecules. The interface between the boroxine group and the gold surface has been characterized in terms of its electronic properties, revealing the existence of an ultra-fast charge delocalization channel in the proximity of the oxygen atoms of the heterocyclic group. More specifically, the DFT calculations show the presence of an unoccupied electronic state localized on both the oxygen atoms of the adsorbed triphenylboroxine and the gold atoms of the topmost layer. By means of resonant Auger electron spectroscopy, we demonstrate that this interface state represents an ultra-fast charge delocalization channel. Boroxine groups are among the most widely adopted building blocks in the synthesis of covalent organic frameworks on surfaces. Our findings indicate that such systems, typically employed as templates for the growth of organic films, can also act as active interlayers that provide an efficient electronic transport channel bridging the inorganic substrate and organic overlayer.

Experimental and Theoretical Investigation of the Restructuring Process Induced by CO at Near Ambient Pressure: Pt Nanoclusters on Graphene/Ir(111).

The adsorption of CO on Pt nanoclusters grown in a regular array on a template provided by the graphene/Ir(111) Moiré was investigated by means of infrared-visible sum frequency generation vibronic spectroscopy, scanning tunneling microscopy, X-ray photoelectron spectroscopy from ultrahigh vacuum to near-ambient pressure, and ab initio simulations. Both terminally and bridge bonded CO species populate nonequivalent sites of the clusters, spanning from first to second-layer terraces to borders and edges, depending on the particle size and morphology and on the adsorption conditions. By combining experimental information and the results of the simulations, we observe a significant restructuring of the clusters. Additionally, above room temperature and at 0.1 mbar, Pt clusters catalyze the spillover of CO to the underlying graphene/Ir(111) interface.

Carbon dioxide reduction on Ir(111): stable hydrocarbon surface species at near-ambient pressure.

Stable hydrocarbon surface species in the carbon dioxide hydrogenation reaction on Ir(111) were identified by means of infrared-visible sum-frequency generation vibrational spectroscopy and X-ray photoelectron spectroscopy under near-ambient pressure conditions (0.1 mbar). By introducing gas phase binary and ternary mixtures of CO2, CO, and H2 into the reaction chamber, stable ethylidyne and ethynyl species were found at the metal surface above 425 K, in remarkable analogy with that observed during the ethylene decomposition process yielding graphene. In addition, upon increasing temperature (up to 600 K depending on the reaction conditions), vibrational and electronic spectroscopic fingerprints appeared that could be attributed to the nucleation of aromatic hydrocarbons at the edge of metastable graphenic clusters interacting with the metal surface.

Trapping of Charged Gold Adatoms by Dimethyl Sulfoxide on a Gold Surface.

We report the formation of dimethyl sulfoxide (DMSO) molecular complexes on Au(111) enabled by native gold adatoms unusually linking the molecules via a bonding of ionic nature, yielding a mutual stabilization between molecules and adatom(s). DMSO is a widely used polar, aprotic solvent whose interaction with metal surfaces is not fully understood. By combining X-ray photoelectron spectroscopy, low temperature scanning tunneling microscopy, and density functional theory (DFT) calculations, we show that DMSO molecules form complexes made by up to four molecules arranged with adjacent oxygen terminations. DFT calculations reveal that most of the observed structures are accurately reproduced if, and only if, the negatively charged oxygen terminations are linked by one or two positively charged Au adatoms. A similar behavior was previously observed only in nonstoichiometric organic salt layers, fabricated using linkage alkali atoms and strongly electronegative molecules. These findings suggest a motif for anchoring organic adlayers of polar molecules on metal substrates and also provide nanoscale insight into the interaction of DMSO with gold.

A competitive amino-carboxylic hydrogen bond on a gold surface.

An amino-carboxylic motif is identified as a novel synthon in the formation of 2D hetero-organic architectures at surfaces. The well-defined interacting scheme we describe herein represents an ideal prototypical system for further investigation of the interaction at surfaces of the two functional groups.

Metabonomics analysis of urine and plasma from rats given long-term and low-dose dimethoate by ultra-performance liquid chromatography-mass spectrometry.

This study assessed the effects of long-term, low-dose dimethoate administration to rats by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). Dimethoate (0.04, 0.12, and 0.36 mg/kg body weight/day) was administered daily to male Wistar rats through their drinking water for 24 weeks. Significant changes in serum clinical chemistry were observed in the middle- and high-dose groups. UPLC-MS revealed evident separate clustering among the different dose groups using global metabolic profiling by supervised partial least squares-discriminant analysis. Metabonomic analysis showed alterations in a number of metabolites (12 from urine and 13 from plasma), such as L-tyrosine, dimethylthiophosphate (DMTP), dimethyldithiophosphate (DMDTP), citric acid, uric acid, suberic acid, glycylproline, allantoin, isovalerylglutamic acid and kinds of lipids. The results suggest that long-term, low-dose exposure to dimethoate can cause disturbances in liver function, antioxidant and nervous systems, as well as the metabolisms of lipids, glucose, fatty acids, amino acids, and collagen in rats. DMTP and DMDTP, which had the most significant changes among all other studied biomarkers, were considered as early, sensitive biomarkers of exposure to dimethoate. The other aforementioned proposed toxicity biomarkers in metabonomic analysis may be useful in the risk assessment of the toxic effects of dimethoate. Metabonomics as a systems toxicology approach was able to provide comprehensive information on the dynamic process of dimethoate induced toxicity. In addition, the results indicate that metabonomic approach could detect systemic toxic effects at an earlier stage compared to clinical chemistry. The combination of metabonomics and clinical chemistry made the toxicity of dimethoate on rats more comprehensive.