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The dysregulation of epigenetic modification and energy metabolism cooperatively contribute to the tumorigenesis of nasopharyngeal carcinoma (NPC). However, the detailed mechanisms underlying their joint contribution to NPC development and progression remain unclear. Here, we investigate the role of Acy1 Coenzyme A Acyltransferases1 (ACAT1), a key enzyme in the metabolic pathway of ketone bodies, in the proliferation and metastasis of NPC and to elucidate the underlying molecular mechanisms. Ketogenesis, plays a critical role in tumorigenesis. Previously, we reported two enzymes involved in ketone body metabolism mediate epigenetic silencing and act as tumor suppressor genes in NPC. Here, we identify another key enzyme, Acetyl-CoA acetyltransferase 1 (ACAT1), and show that its transcriptional inactivation in NPC is due to promoter hypermethylation. Ectopic overexpression of ACAT1 significantly suppressed the proliferation and colony formation of NPC cells in vitro. The migratory and invasive capacity of NPC cells was inhibited by ACAT1. The tumorigenesis of NPC cells overexpressing ACAT1 was decreased in vivo. Elevated ACAT1 in NPC cells was accompanied by an elevated expression of CDH1 and a reduced expression of vimentin and SPARC, strongly indicating that ACAT1 is involved in regulating epithelial-mesenchymal transition (EMT). We also found that ACAT1 contributes to increased intracellular levels of β-hydroxybutyrate (β-HB). Exogenously supplied β-HB significantly inhibits the growth of NPC cells in a dose-dependent manner. In summary, ACAT1 may function as a tumor suppressor via modulation of ketogenesis and could thus serve as a potential therapeutic target in NPC. In summary, our data suggest that regulation of ketogenesis may serve as adjuvant therapy in NPC.

The formation of macromolecules is an indispensable step in the process leading to the appearance of life on Earth. As their constituents were widely distributed over geological time and space on the surface of the primitive Earth, clay minerals are regarded as an essential factor influencing the formation of macromolecules due to their high reactivity and their close association with organic matter that could be the precursors of macromolecules. Over the years, many researchers have studied the roles of clay minerals in macromolecules formation through the condensation of amino acids (AAs) in aqueous systems in order to understand the thermal evolution of organic matter (OM) in pristine oceans. However, the condensation of AAs in non-aqueous systems has received limited attention. In particular, the stability and evolution of AAs in volcanic eruption environments that are rich in clay minerals have rarely been investigated. In this work, the influence of clay mineral on the thermal evolution of AAs was studied. Two types of clay-AA complexes, i.e., clay-AA interlayer complexes and clay-AA external complexes (where AAs exist outside the interlayer structure) were used. An expandable clay mineral, montmorillonite (Mt), was chosen as the typical clay mineral, and L-arginine (Arg) and glycine (Gly) were used as the model AAs for the preparation of clay-AA complexes. In situ diffuse-reflectance infrared Fourier transform spectroscopy (in situ DRIFT) was used to monitor the thermal evolution behaviors of the clay-AA complexes, such as the formation of macromolecules with peptide bonds, and thermogravimetry (TG) and TG coupled with Fourier transform infrared spectroscopy (TG-FTIR) analyses were used to investigate the decomposition of the produced macromolecules. The results show that Mt strongly affects macromolecules formation during the thermal evolution of AAs, which is mainly due to that the inherent solid acidity of the different structural sites of Mt varies. When AAs are present on the external surfaces of Mt, the interaction between AAs and clay minerals substantially decreases the initial formation temperature of the macromolecules with peptide bonds (for Arg) and strongly affects the types of condensation products (for Gly). When AAs exist in the interlayer structure of Mt, the interlayer structure has a steric effect on the thermal evolution of these monomers, which, together with the effects of the molecular structure of Arg, enhances the initial temperature of condensation and increases the thermal decomposition temperature of the formed macromolecules. Regardless of whether AAs exist in the interlayer sites or on the external surfaces of clay minerals, clay-OM association is able to protect macromolecules, postponing their thermal decomposition. The present work indicates that macromolecules with peptide bonds could readily form via the condensation of AAs under dry high-temperature conditions, which implies that non-aqueous thermal conditions resulting from volcanic activities might be a favorable geological setting for prebiotic chemical evolution on the early Earth.

This work investigated changes in the chemical composition, structure and porosity of hollow spherical allophane under alkaline conditions, which are significant not only for understanding its fate in natural environment but also for its functional applications. Hollow spherical allophane with a silicon/aluminium (Si/Al) molar ratio of 0.77 was hydrothermally synthesised followed by treatment with dilute sodium hydroxide (NaOH) solutions with different concentrations (indicated by pH values). The allophane and its alkali-treated products were then characterized using a combination of techniques, such as Fourier-transform infrared spectroscopy, nuclear magnetic resonance and nitrogen physisorption analysis. Allophane showed a weak structural stability in alkaline conditions. At pH ≤ 11.0, the framework of allophane particles was almost intact; its polymerised silicates showed only slight dissolution. At a higher pH (> 11.0), desilication and dealumination enhanced, resulting in the destruction of the imogolite local structure (ImoLS) along the edges of defect pores and the formation of amorphous materials. Most of the defect pores increased in size, becoming accessible to nitrogen and the textural parameters of the micropores reached their maximum values at a pH of 12.5. However, the damage to some secondary pores and the collapse of some hollow spherules reduced total pore volume (Vtotal). At a pH of 13.0, most of the hollow spherules were observed to have collapsed, resulting in remarkable decrease in the textural parameters. However, some unbroken and/or mildly broken allophane particles might remain, deduced from the relatively high BET specific surface area (SSA) and Vtotal and the considerable proportion of micropores for Allo13.0. These results reveal the dissolution behaviour of allophane in alkaline conditions and the mechanism underlying this behaviour, providing essential insights into the mineral's potential applications.

Halloysite is a hydrated polymorph of kaolinite but possesses a distinctive nanosized tubular structure and surface reactivity. The microstructure and mechanical performance of geopolymers derived from calcined halloysite via acid-activation were investigated in this study. The acid-activation products were characterized using a combination of techniques including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Acid-activation of halloysite calcined at 450 °C by 6 mol/L and 10 mol/L phosphoric acid solution produced metavariscite crystals. When the phosphoric acid concentration was increased to 14 mol/L, the acid-activation product became more compact due to the formation of geopolymer that were mainly composed of Al–O–P networks. Calcination of halloysite at 750 °C led to an active form of halloysite, which was favored by geopolymerization. Higher phosphoric acid concentration led to the incorporation of more Si and P in the geopolymer matrix with Si–O–P–O–Al networks, and thus greater compressive strength. Halloysites calcined at 1000 °C barely reacted with phosphoric acid, due to the nanocrystalline formation and the decreased Si–OH content in the calcined halloysite, which had low reactivity unfavorable for geopolymerization. These results indicated that the microstructure and mechanical performance of halloysite-based geopolymers are highly dependent on the precalcination temperature of halloysite and the phosphoric acid concentration. Suitable precalcination temperature and high concentration of phosphoric acid facilitate high degree of geopolymerization, which is conducive to the formation of an acid-activated halloysite-based geopolymer with excellent mechanical performance.

In this work, halloysite-CeOx (x = 1.5–2.0) nanocomposites were prepared using a redox-precipitation method, and the As(III) removal performance of the obtained materials was evaluated. These composites were formed by supporting CeO2 nanoparticles on the chemically modified halloysite substrate. The modification of halloysite using a facile NaOH treatment dramatically increased the inner-surface and inner hydroxyl groups. These increased groups significantly enhanced the dispersion of the coating of CeO2 nanoparticles due to electrostatic interactions. The specific surface area and pore volume of the optimized Hal0.01Ce composite was 91.1 m2/g and 0.16 cm3/g, respectively. This composite exhibited an excellent As(III) adsorption capacity (209.3 mg/g CeO2), which was much higher than the unmodified halloysite-CeOx composite (158.5 mg/g CeO2) and unsupported CeO2 nanoparticles (61.9 mg/g). The As(III) adsorption mechanisms on this composite involved the formation of surface complexes and oxidation of partial As(III) followed by As(V) adsorption. In addition, the Hal0.01Ce composite also possessed selective adsorption for As(III) in the presence of coexisting ions and maintained 91.4% of the As(III) removal efficiency after three regeneration cycles. These results demonstrate that this composite can be used as a potential candidate for As(III) removal from contaminated water.