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Metabolic reprogramming plays a critical role in tumorigenesis and tumor progression. The metabolism and the proliferation of tumors are regulated by both intrinsic factors within the tumor and the availability of metabolites in the tumor microenvironment (TME). The metabolic niche within the TME is primarily orchestrated at 3 levels: 1) the regulation of tumor metabolism by factors intrinsic to the tumors, 2) the interaction between tumor cells and T cells, macrophages, and stromal cells, and 3) the metabolic heterogeneity of tumor cells within the tissue space. Herein, we provided a concise overview of the various metabolic regulatory modes observed in tumor cells. Additionally, we extensively analyzed the interaction between tumor cells and other cells within the TME, as well as the metabolic characteristics and functions of different types of cells. Ultimately, this review provides a theoretical basis and novel insights for the precision treatment of tumors.

The Promoting Role of HK II in Tumor Development and the Research Progress of Its Inhibitors.

Increased glycolysis is a key characteristic of malignant cells that contributes to their high proliferation rates and ability to develop drug resistance. The glycolysis rate-limiting enzyme hexokinase II (HK II) is overexpressed in most tumor cells and significantly affects tumor development. This paper examines the structure of HK II and the specific biological factors that influence its role in tumor development, as well as the potential of HK II inhibitors in antitumor therapy. Furthermore, we identify and discuss the inhibitors of HK II that have been reported in the literature.

Metabolic engineering of Saccharomyces cerevisiae for gram-scale diosgenin production.

Diosgenin (DSG) is a naturally occurring steroidal saponin with a variety of biological activities that is also an important precursor for the synthesis of various steroidal drugs. The traditional industrial production of DSG is based on natural plant extraction and chemical processing. However, the whole process is time-consuming, laborious, and accompanied by severe environmental pollution. Therefore, it is necessary to develop a more convenient and environmentally-friendly process to realize the green production of DSG. In our previous work, we achieved de novo synthesis of DSG in Saccharomyces cerevisiae using glucose as the carbon source. However, DSG production was only at the milligram level, which is too low for industrial production. In this work, we further developed yeast strains for DSG overproduction by optimizing the synthesis pathway, fine-tuning pathway gene expression, and eliminating competing pathways. Cholesterol 22-hydroxylase was used to construct the DSG biosynthesis pathway. The optimal ratio of cytochrome P450 (CYP) to cytochrome P450 reductase (CPR) associated with DSG synthesis was screened to increase DSG production. Weakening the expression of the ERG6 gene further increased DSG synthesis and reduced the formation of by-products. In addition, we investigated the impact of DSG accumulation on yeast cell physiology and growth by transcriptome analysis and found that the multidrug transporter PDR5 and the sterol-binding protein PRY1 contributed to DSG production. Finally, we obtained a DSG titer of 2.03 g/L after 288 h of high-cell-density fed-batch fermentation using the engineered strain LP118, which represents the highest DSG titer reported to date for a yeast de novo synthesis system.

Improving astaxanthin production in Escherichia coli by co-utilizing CrtZ enzymes with different substrate preference.

BACKGROUND: The bifunctional enzyme ß-carotene hydroxylase (CrtZ) catalyzes the hydroxylation of carotenoid ß-ionone rings at the 3, 3' position regardless of the presence of keto group at 4, 4' position, which is an important step in the synthesis of astaxanthin. The level and substrate preference of CrtZ may have great effect on the amount of astaxanthin and the accumulation of intermediates. RESULTS: In this study, the substrate preference of PCcrtZ from Paracoccus sp. PC1 and PAcrtZ from Pantoea Agglomerans were certified and were combined utilization for increase astaxanthin production. Firstly, PCcrtZ from Paracoccus sp. PC1 and PAcrtZ from P. Agglomerans were expressed in platform strains CAR032 (ß-carotene producing strain) and Can004 (canthaxanthin producing strain) separately to identify their substrate preference for carotenoids with keto groups at 4,4' position or not. The results showed that PCcrtZ led to a lower zeaxanthin yield in CAR032 compared to that of PAcrtZ. On the contrary, higher astaxanthin production was obtained in Can004 by PCcrtZ than that of PAcrtZ. This demonstrated that PCCrtZ has higher canthaxanthin to astaxanthin conversion ability than PACrtZ, while PACrtZ prefer using ß-carotene as substrate. Finally, Ast010, which has two copies of PAcrtZ and one copy of PCcrtZ produced 1.82 g/L of astaxanthin after 70 h of fed-batch fermentation. CONCLUSIONS: Combined utilization of crtZ genes, which have ß-carotene and canthaxanthin substrate preference respectively, can greatly enhance the production of astaxanthin and increase the ratio of astaxanthin among total carotenoids.

Helicase-AID: A novel molecular device for base editing at random genomic loci.

CRISPR-enabled deaminase base editing has become a powerful tool for precisely editing nucleotides on the chromosome. In this study DNA helicases, such as Escherichia coli DnaB, were fused to activation-induced cytidine deaminase (AID) to form enzyme complexes which randomly introduces edited bases throughout the chromosome. DnaB-AID was found to increase 2.5 × 103 fold relative to the mutagenesis frequency of wildtype. 97.9% of these edits were observed on the leading strand during DNA replication suggesting deamination to be highly coordinated with DNA replication. Using DnaB-AID, a 371.4% increase in ß-carotene production was obtained following four rounds of editing. In Saccharomyces cerevisiae Helicase-AID was constructed by fusing AID to one of the subunits of eukaryotic helicase Mcm2-7 complex, MCM5. Using MCM5-AID, the average editing efficiency of five strains was 2.1 ± 0.4 × 103 fold higher than the native genomic mutation rate. MCM5-AID was able to improve ß-carotene production of S. cerevisiae 4742crt by 75.4% following eight rounds of editing. The S. cerevisiae MCM5-AID technique is the first biological tool for generating and accumulating single base mutations in eukaryotic chromosomes. Since the helicase complex is highly conservative in all eukaryotes, Helicase-AID could be adapted for various applications and research in all eukaryotic cells.

Tunable graphene-based metasurface for an ultra-low sidelobe terahertz phased array antenna.

In this paper, we propose an all-solid-state, electrically tunable, and reflective graphene metasurface array that can generate a specific phase or continuous scanning between 0° and 352.5° in the terahertz band. By optimizing the structural parameters of the metasurface, the average reflectivity can reach 68.3%, and the maximum reflectivity variation range is only 30%. We also simulate the results that an electrically tunable terahertz phased array can be achieved by adjusting the Fermi levels of a monolayer graphene resonator. The maximum deflection of the reflected beam is 46.05°, and the resolution can be improved to 1.10°. It should be noted that the sidelobe energy only accounts for 1.06% of the main lobe energy, due to the slight change in reflectivity with the phase gradient.

UHRF1 Knockdown Attenuates Cell Growth, Migration, and Invasion in Cutaneous Squamous Cell Carcinoma.

Ubiquitin like with PHD and ring finger domains 1 (UHRF1) contributes to the progression of many cancers. Here, we firstly observed UHRF1 was elevated in cutaneous squamous cell carcinoma (cSCC) and related to the differentiation stages. Knockdown of UHRF1 in A431 and Scl-1 attenuated cell proliferation, migration, and invasion, leading to G2/M cell cycle arrest and apoptosis. Through a mouse xenograft model, we found UHRF1 deficiency ameliorated tumor growth. These results may be associated with destruction of multiple signal pathways. In summary, our results suggest UHRF1 is involved in the pathogenesis of cSCC and may be a therapeutic target.

Enhanced detectivity of PbS quantum dots infrared photodetector by introducing the tunneling effect of PMMA.

With extremely high optical absorption coefficient in infrared regime, lead sulfide (PbS) quantum dots (QDs)-based photodetectors are promising for diverse applications. In recent years, synthesis of materials has made great progress, but the problem of low sensitivity of quantum dots photodetector still unresolved. In this work, the introduction of a tunneling organic layer effectively address this problem. The dark current is decreased by the appropriate thickness of polymethyl methacrylate (PMMA) barrier layer by suppressing the spontaneous migration of ions, and the photogenerated carriers are little effected, thereby the responsivity of the device is improved. As a result, the device exhibits a high responsivity of 3.73 × 105 mA W-1 and a giant specific detectivity of 4.01 × 1013 Jones at a low voltage of -1 V under 1064 nm illumination. In the self-powered mode, the responsivity reaches a value of 157.6 mA W-1, and the detectivity up to 5.9 × 1011 Jones. The performance of the photodetectors is obviously better than most of the reported QDs photodetectors. The design of this device structure provides a new solution to the problem of low sensitivity and high leakage current of quantum dots based infrared photodetectors.

Ultralow sidelobe midinfrared optical phased array based on a broadband metasurface.

In this paper, we propose an all-solid-state and ultralow sidelobe optical phased array (OPA) through designing a broadband angle-insensitive reflective metasurface in the midinfrared. The simulation results show that the metasurface can realize the wide-frequency metareflection characteristics in the range of 4.3∼5.0µm. Notably, the metasurface array can almost generate a continuous sweep between 0° and 342°, while the variation of reflectivity amplitude is only 10.2%, by changing the corresponding structural parameters. Then, we design and simulate an OPA based on these excellent characteristics of the broadband metasurface. By simply changing the periodicity of the OPA structure, the continuous deflection angles can be achieved within 29.41°, which can increase to 44.06° by changing the angle of the incident beam. A key feature of our design is that the sidelobe energy is less than 3.10% of the main lobe energy.

Ultrabroadband, Ultraviolet to Terahertz, and High Sensitivity CH3NH3PbI3 Perovskite Photodetectors.

Owning to the unique optical and electronic properties, organic-inorganic hybrid perovskites have made impressive progress in photodetection applications. However, achieving ultrabroadband detection over the ultraviolet (UV) to terahertz (THz) range remains a major challenge for perovskite photodetectors. Here, we report an ultrabroadband (UV-THz) dual-mechanism photodetector based on CH3NH3PbI3 films. The photoresponse of the PD in the UV-visible (vis) and near-infrared (NIR)-THz bands is mainly caused by the photoconductive (PC) effect and bolometric effect, respectively. High responsivities ranging from 105 to 102 mA W-1 are acquired within UV-THz bands under 1 V bias voltage at room temperature. Moreover, the device also shows fast rise and decay times of 76 and 126 ns under 1064 nm laser illumination, respectively. This work provides insight into the thermoelectric characteristics of perovskite and offers a new way to realize ultrabroadband photodetectors notably for THz detector at room temperature.

Optical control of terahertz plasmon-induced transparency based on hybrid CsPbBr3 quantum dot metasurfaces.

Incorporating photosensitive material into structured metamaterials explores opportunities for dynamical operation across the terahertz functional devices, enabled by the efficient interaction between light and matter. In this work, the CsPbBr3 quantum dots are incorporated into the metasurfaces, realizing the active control of the plasmon-induced transparency. In the experiment, the normalized modulation depth of transparency effect is up to 74%. Rigorous numerical and theoretical simulations verify that the variation of dynamic physical process is associated with the charge storage capacity in the capacitive metasurface. An observed phase advance and group delay indicate the hybrid metasurface is useful for slow light application. In addition, the simple process provides a convenient way for the development of terahertz functional devices.

Manipulating the position of DNA expression cassettes using location tags fused to dCas9 (Cas9-Lag) to improve metabolic pathway efficiency.

BACKGROUND: Deactivated Cas9 (dCas9) led to significant improvement of CRISPR/Cas9-based techniques because it can be fused with a variety of functional groups to form diverse molecular devices, which can manipulate or modify target DNA cassettes. One important metabolic engineering strategy is to localize the enzymes in proximity of their substrates for improved catalytic efficiency. In this work, we developed a novel molecular device to manipulate the cellular location of specific DNA cassettes either on plasmids or on the chromosome, by fusing location tags to dCas9 (Cas9-Lag), and applied the technique for synthetic biology applications. Carotenoids like ß-carotene serve as common intermediates for the synthesis of derivative compounds, which are hydrophobic and usually accumulate in the membrane compartment. RESULTS: Carotenoids like ß-carotene serve as common intermediates for the synthesis of derivative compounds, which are hydrophobic and usually accumulate in the membrane components. To improve the functional expression of membrane-bound enzymes and localize them in proximity to the substrates, Cas9-Lag was used to pull plasmids or chromosomal DNA expressing carotenoid enzymes onto the cell membrane. For this purpose, dCas9 was fused to the E. coli membrane docking tag GlpF, and gRNA was designed to direct this fusion protein to the DNA expression cassettes. With Cas9-Lag, the zeaxanthin and astaxanthin titer increased by 29.0% and 26.7% respectively. Due to experimental limitations, the electron microscopy images of cells expressing Cas9-Lag vaguely indicated that GlpF-Cas9 might have pulled the target DNA cassettes in close proximity to membrane. Similarly, protein mass spectrometry analysis of membrane proteins suggested an increased expression of carotenoid-converting enzymes in the membrane components. CONCLUSION: This work therefore provides a novel molecular device, Cas9-Lag, which was proved to increase zeaxanthin and astaxanthin production and might be used to manipulate DNA cassette location.

Self-driven visible-near infrared photodetector with vertical CsPbBr3/PbS quantum dots heterojunction structure.

Self-driven photodetectors are widely used in communication and imaging. As a newly developed semiconductor material, perovskite quantum dots (QDs) are not only bandgap tunable, but also easily combined with other materials. In this paper, a vertical structure self-driven photodetector based on heterojunction of CsPbBr3 QDs and PbS QDs is proposed, and the device is prepared by solution spin coating method. The device can work in visible and near infrared (400-1130 nm) regions, and has excellent performance, such as ultrafast response speed (rise and decay time are 0.4 µs/0.73 µs under 532 nm laser irradiation in self-driven mode, the estimated response time under 1064 nm laser irradiation is about 11.5 µs), more than 100 dB linear dynamic range for both visible and infrared regions, and good stability. Similarly, the responsivity of the photodetector can also reach an average of 10 mA W-1, and the detectivity is 1.13 × 1010 Jones at 0 V bias for 1064 nm laser irradiation. The device combines two kinds of QDs revealing its good prospects and great advantages in self-driven photodetectors and high-speed optical communication devices.

Light enhanced low-voltage nonvolatile memory based on all-inorganic perovskite quantum dots.

Light enhanced low-voltage nonvolatile memory was prepared using all-inorganic perovskite quantum dots (QDs) as a semiconductor layer and Ag nanoparticles (NPs) as a floating gate layer. The photo-induced carriers can be produced in CsPbBr3 QDs under ultraviolet light and trapped in Ag NPs under the action of an external electric field. With the assistance of light, the device exhibited a significantly larger memory window (ΔV th) under low programming and erasing voltages of ±5 V owing to the use of CsPbBr3 QDs. Furthermore, we proved that the ΔV th of the memory strongly depended on the applied bias voltage (V DS) as well as still remaining at 79.3% after 105 s at V DS of 1.4 V. The facile memory provides a new approach to trap a photo-induced charge and reduce operating voltages by combining QDs with metal NPs.

Construction of an alternative glycerol-utilization pathway for improved ß-carotene production in Escherichia coli.

Glycerol, which is an inevitable by-product of biodiesel production, is an ideal carbon source for the production of carotenoids due to its low price, good availability and chemically reduced status, which results in a low requirement for additional reducing equivalents. In this study, an alternative carbon-utilization pathway was constructed in Escherichia coli to enable more efficient ß-carotene production from glycerol. An aldehyde reductase gene (alrd) and an aldehyde dehydrogenase gene (aldH) from Ralstonia eutropha H16 were integrated into the E. coli chromosome to form a novel glycerol-utilization pathway. The ß-carotene specific production value was increased by 50% after the introduction of alrd and aldH. It was found that the glycerol kinase gene (garK), alrd and aldH were the bottleneck of the alternative glycerol metabolic pathway, and modulation of garK gene with an mRS library further increased the ß-carotene specific production value by 13%. Finally, co-modulation of genes in the introduced aldH-alrd operon led to 86% more of ß-carotene specific production value than that of the strain without the alternative glycerol-utilization pathway and the glycerol-utilization rate was also increased. In this work, ß-carotene production of E. coli was significantly improved by constructing and optimizing an alternative glycerol-utilization pathway. This strategy can potentially be used to improve the production of other isoprenoids using glycerol as a cheap and abundant substrate, and therefore has industrial relevance.

A Fast Response-Recovery 3D Graphene Foam Humidity Sensor for User Interaction.

Humidity sensors allow electronic devices to convert the water content in the environment into electronical signals by utilizing material properties and transduction techniques. Three-dimensional graphene foam (3DGF) can be exploited in humidity sensors due to its convenient features including low-mass density, large specific surface area, and excellent electrical. In this paper, 3DGF with super permeability to water enables humidity sensors to exhibit a broad relative humidities (RH) range, from 0% to 85.9%, with a fast response speed (response time: ~89 ms, recovery time: ~189 ms). To interpret the physical mechanism behind this, we constructed a 3DGF model decorated with water to calculate the energy structure and we carried out the CASTEP as implemented in Materials Studio 8.0. This can be ascribed to the donor effect, namely, the electronic donation of chemically adsorbed water molecules to the 3DGF surface. Furthermore, this device can be used for user interaction (UI) with unprecedented performance. These high performances support 3DGF as a promising material for humidity sensitive material.

Balanced activation of IspG and IspH to eliminate MEP intermediate accumulation and improve isoprenoids production in Escherichia coli.

The MEP pathway genes were modulated to investigate whether there were new rate-limiting steps and toxic intermediates in this pathway. Activating IspG led to significant decrease of cell growth and ß-carotene production. It was found that ispG overexpression led to accumulation of intermediate HMBPP, which seriously interfered with synthesis machinery of nucleotide and protein in Escherichia coli. Activation of the downstream enzyme IspH could solve HMBPP accumulation problem and eliminate the negative effects of ispG overexpression. In addition, intermediate MECPP accumulated in the starting strain, while balanced activation of IspG and IspH could push the carbon flux away from MECPP and led to 73% and 77% increase of ß-carotene and lycopene titer respectively. Our work for the first time identified HMBPP to be a cytotoxic intermediate in MEP pathway and demonstrated that balanced activation of IspG and IspH could eliminate accumulation of HMBPP and MECPP and improve isoprenoids production.

Membrane engineering - A novel strategy to enhance the production and accumulation of ß-carotene in Escherichia coli.

Carotenoids are a class of terpenes of commercial interest that exert important biological functions. While various strategies have been applied to engineer ß-carotene production in microbial cell factories, no work has been done to study and improve the storage of hydrophobic terpene products inside the heterologous host cells. Although the membrane is thought to be the cell compartment that accumulates hydrophobic terpenes such as ß-carotene, direct evidence is still lacking. In this work, we engineered the membrane of Escherichia coli in both its morphological and biosynthetic aspects, as a means to study and improve its storage capacity for ß-carotene. Engineering the membrane morphology by overexpressing membrane-bending proteins resulted in a 28% increase of ß-carotene specific producton value, while engineering the membrane synthesis pathway led to a 43% increase. Moreover, the combination of these two strategies had a synergistic effect, which caused a 2.9-fold increase of ß-carotene specific production value (from 6.7 to 19.6mg/g DCW). Inward membrane stacks were observed in electron microscopy images of the engineered E. coli cells, which indicated that morphological changes were associated with the increased ß-carotene storage capacity. Finally, membrane separation and analysis confirmed that the increased ß-carotene was mainly accumulated within the cell membrane. This membrane engineering strategy was also applied to the ß-carotene hyperproducing strain CAR025, which led to a 39% increase of the already high ß-carotene specific production value (from 31.8 to 44.2mg/g DCW in shake flasks), resulting in one of the highest reported specific production values under comparable culture conditions. The membrane engineering strategy developed in this work opens up a new direction for engineering and improving microbial terpene producers. It is quite possible that a wide range of strains used to produce hydrophobic compounds can be further improved using this novel engineering strategy.

miR-3117 regulates hepatocellular carcinoma cell proliferation by targeting PHLPPL.

Altered microRNA expression is associated with tumor proliferation, metastasis, and tumorigenesis. In this study, we studied the role of miR-3117 in hepatocellular carcinoma (HCC) cell proliferation and found that miR-3117 was upregulated in HCC tissues and cells. MTT assay, soft agar growth assay, BrdU assay, and cell cycle assay revealed that miR-3117 overexpression promoted HCC HepG2 cell proliferation and that knockdown of miR-3117 suppressed HepG2 proliferation. Mechanism analysis suggested PH domain and leucine-rich repeat protein phosphatase-like (PHLPPL) as the target of miR-3117. Luciferase reporter assay suggested that miR-3117 directly binds to the 3'UTR of PHLPPL. Double knockdown of miR-3117 and PHLPPL copied the phenotypes caused by miR-3117 overexpression, suggesting that miR-3117 contributes to the proliferation of HepG2 by targeting PHLPPL. Our study provided a target for HCC therapy.

Type IIs restriction based combinatory modulation technique for metabolic pathway optimization.

BACKGROUND: One of the most important research subjects of metabolic engineering is pursuing a balanced metabolic pathway, which is the basis of an efficient cell factory. In this work, we dedicated to develop a simple and efficient technique to modulate expression of multiple genes simultaneously, and select for the optimal regulation pattern. RESULTS: A Type IIs restriction based combinatory modulation (TRCM) technique was designed and established in the research. With this technique, a plasmid library containing variably regulated mvaE, mvaS, mvaK 1 , mvaD and mvaK 2 of the mevalonate (MVA) pathway were obtained and transformed into E. coli DXS37-IDI46 to obtain a ß-carotene producer library. The ratio of successfully assembled plasmids was determined to be 35%, which was increased to 100% when color based pre-screening was applied. Representative strains were sequenced to contain diverse RBSs as designed to regulate expression of MVA pathway genes. A relatively balanced MVA pathway was achieved in E. coli cell factory to increase the ß-carotene yield by two fold. Furthermore, the approximate regulation pattern of this optimal MVA pathway was illustrated. CONCLUSIONS: A TRCM technique for metabolic pathway optimization was designed and established in this research, which can be applied to various applications in terms of metabolic pathway regulation and optimization.