SP1 transcriptionally upregulates the expression of APOC3 in KGN cells to promote disease progression by regulating TLR2/NF-κB signalling pathway.

INTRODUCTION: Apolipoprotein C3 (APOC3) is known for its important functions in metabolism-related diseases. However, the function and molecular mechanism of APOC3 in polycystic ovarian syndrome (PCOS) have not been reported. MATERIAL AND METHODS: Quantitative polymerase chain reaction and western blot assays were used to detect the expression of APOC3 in KGN cells. Small interference APOC3 (siAPOC3) was applied to reduce APOC3 expression, and the proliferation ability of human granulosa cell line (KGN cells) was measured by cell counting kit-8 and colony formation assays. The protein levels of key genes related to apoptosis were detected by western blot assay. The transcriptional regulator of APOC3 was predicted by the UCSC and PROMO website, and verified by dual luciferase assay. siAPOC3 and pcDNA3.1-specific protein 1 (SP1) vector were co-transfected into KGN cells to detect the function of SP1 and APOC3 in KGN cells. RESULTS: APOC3 was overexpressed in KGN cells, and siAPOC3 transfection significantly reduced the growth ability of KGN cells and increased the apoptosis ability of KGN cells. SP1 directly bound to the promoter of APOC3 and transcriptional regulated APOC3 expression. Overexpression of SP1 increased the growth ability of KGN cells and decreased the apoptosis ability of KGN cells, which were reversed after siAPOC3 transfection. The increased levels of toll-like receptor 2 (TLR2) and p65 phosphorylation (p-P65) nuclear factor kappa B (NF-κB) caused by SP1 overexpression were inhibited by siAPOC3 transfection. APOC3, transcriptionally regulated by SP1, promoted the growth of KGN cells, and inhibited the apoptosis by regulating TLR2/NF-κB signalling pathway.

Effects and mechanisms of anion and cation on the gelation of nanosilica sol by all-atom molecular dynamics simulation: promotion or inhibition?

Nanosilica sol (NSS) is prone to gelation due to the condensation of silicon hydroxyl at normal temperature and pressure, which is further exacerbated by the addition of electrolytes during production. Therefore, the effects of ions and the mechanism of gelation of NSS are crucial for its stability. Herein, all-atom molecular dynamics (AAMD) was carried out to explore the effects and mechanisms of cations (K+, Na+, Ca2+) and anions (Cl-, NO3-, SO42-, PO43-) on the sol-gel transition. Results indicated that highly electrophilic cations (e.g., Ca2+) and anions with slightly stronger nucleophilicity than Si(OH)3O- (e.g., NO3-) could inhibit gelation by preventing Si(OH)4 and Si(OH)3O- from approaching the silica surface. Such inhibition is more pronounced in NSS with larger particle sizes. Our findings offer some critical insights into the effects of ions on the gel stability of NSS, which also contributes significantly to screening suitable electrolytes for the production of NSS.

Determination of a six-gene prognostic model for cervical cancer based on WGCNA combined with LASSO and Cox-PH analysis.

AIM: This study aimed to establish a risk model of hub genes to evaluate the prognosis of patients with cervical cancer. METHODS: Based on TCGA and GTEx databases, the differentially expressed genes (DEGs) were screened and then analyzed using GO and KEGG analyses. The weighted gene co-expression network (WGCNA) was then used to perform modular analysis of DEGs. Univariate Cox regression analysis combined with LASSO and Cox-pH was used to select the prognostic genes. Then, multivariate Cox regression analysis was used to screen the hub genes. The risk model was established based on hub genes and evaluated by risk curve, survival state, Kaplan-Meier curve, and receiver operating characteristic (ROC) curve. RESULTS: We screened 1265 DEGs between cervical cancer and normal samples, of which 620 were downregulated and 645 were upregulated. GO and KEGG analyses revealed that most of the upregulated genes were related to the metastasis of cancer cells, while the downregulated genes mostly acted on the cell cycle. Then, WGCNA mined six modules (red, blue, green, brown, yellow, and gray), and the brown module with the most DEGs and related to multiple cancers was selected for the follow-up study. Eight genes were identified by univariate Cox regression analysis combined with the LASSO Cox-pH model. Then, six hub genes (SLC25A5, ENO1, ANLN, RIBC2, PTTG1, and MCM5) were screened by multivariate Cox regression analysis, and SLC25A5, ANLN, RIBC2, and PTTG1 could be used as independent prognostic factors. Finally, we determined that the risk model established by the six hub genes was effective and stable. CONCLUSIONS: This study supplies the prognostic value of the risk model and the new promising targets for the cervical cancer treatment, and their biological functions need to be further explored.

Self-assembly of cyclic grafted copolymers with rigid rings and their potential as drug nanocarriers.

Enhancing the performance of polymer micelles by purposeful regulation of their structures is a challenging topic that receives widespread attention. In this study, we systematically conduct a comparative study between cyclic grafted copolymers with rigid and flexible rings in the self-assembly behavior via dissipative particle dynamics (DPD) simulation. With a focus on the possible stacking ways of rigid rings, we propose the energy-driven packing mechanism of cyclic grafted copolymers with rigid rings. For cyclic grafted copolymers with large ring size (14 and 21-membered rings), rigid rings present a novel channel-layer-combination layout, which is determined by the balance between the potential energy of micelles (Emicelle) and the interaction energy between water and micelles (Eint). Based on this mechanism, we further regulate a series of complex self-assembling structures, including curved rod-like, T-shape, annular and helical micelles. Compared with flexible copolymers, cyclic grafted copolymers with rigid rings provide a larger and loose hydrophobic core and higher structural stability with micelles due to the unique packing way of rigid rings. Therefore, their micelles have a great potential as drug nanocarriers. They possess a better drug loading capacity and disassemble more quickly than flexible counterparts under acidic tumor microenvironment. Furthermore, the endocytosis kinetics of rigid micelles is faster than the flexible counterparts for the adsorption and wrapping process. This study may provide a reasonable idea of structural design for polymer micelles to enhance their performance in biomedical applications.

Reversible Cross-Linked Mixed Micelles for pH Triggered Swelling and Redox Triggered Degradation for Enhanced and Controlled Drug Release.

Good stability and controlled drug release are important properties of polymeric micelles for drug delivery. A good candidate for drug delivery must have outstanding stability in a normal physiological environment, followed with low drug leakage and side effects. Moreover, the chemotherapeutic drug in the micellar core should also be quickly and "on-demand" released in the intracellular microenvironment at the tumor site, which is in favor of overcoming multidrug resistance (MDR) effects of tumor cells. In this work, a mixed micelle was prepared by the simple mix of two amphiphilic copolymers, namely PCL-SS-P(PEGMA-co-MAEBA) and PCL-SS-PDMAEMA, in aqueous solution. In the mixed micelle's core-shell structure, PCL blocks were used as the hydrophobic core, while the micellar hydrophilic shell consisted of two blocks, namely P(PEGMA-co-MAEBA) and PDMAEMA. In the micellar shell, PEGMA provided hydrophilicity and stability, while MAEBA introduced the aldehyde sites for reversible crosslinking. Meanwhile, the PDMAEMA blocks were also introduced in the micellar shell for pH-responding protonation and swelling of the micelle. The disulfide bonds between the hydrophobic core and hydrophilic shell had redox sensitive properties. Reversible cross-linked micelles (RCLMs) were obtained by crosslinking the micellar shell with an imine structure. RCLMs showed good stability and excellent ability against extensive dilution by aqueous solution. In addition, the stability in different conditions with various pH values and glutathione (GSH) concentrations was studied. Then, the anticancer drug doxorubicin (DOX) was selected as the model drug to evaluate drug entrapment and release capacity of mixed micelles. The in vitro release profiles indicated that this RCLM had controlled drug release. In the simulated normal physiological environment (pH 7.4), the drug release of the RCLMs was restrained obviously, and the cumulative drug release content was only 25.7 during 72 h. When it came to acidic conditions (pH 5.0), de-crosslinking of the micelles occurred, as well as protonation of PDMAEMA blocks and micellar swelling at the same time, which enhanced the drug release to a large extent (81.4%, 72 h). Moreover, the drug release content was promoted further in the presence of the reductant GSH. In the condition of pH 5.0 with 10 mM GSH, disulfide bonds broke-up between the micelle core and shell, followed by shedding of the shell from the inner core. Then, the micellar disassembly (degradation) happened based on the de-crosslinking and swelling, and the drug release was as high as 95.3%. The MTT assay indicated that the CLSMs showed low cytotoxicity and good biocompatibility against the HepG2 cells. In contrast, the DOX-loaded CLSMs could efficiently restrain the proliferation of tumor cells, and the cell viability after 48 h incubation was just 13.2%, which was close to that of free DOX. This reversible cross-linked mixed micelle with pH/redox responsive behaviors is a potential nanocarrier for chemotherapy.

The self-assembly behavior of polymer brushes induced by the orientational ordering of rod backbones: a dissipative particle dynamics study.

Dissipative particle dynamics (DPD) simulations were used to study the self-assembly behavior of polymer brushes with rod-coil backbones, polycaprolactone-b-poly(2-(dimethylamino)ethyl methacrylate)-grafted cellulose nanocrystals (CNC-g-PCL-b-PDMAEMA), and to further examine the influences of polymer concentration, rod-block proportion and distribution of backbones and the grafting density of side chains on the resulting aggregate conformations. We proposed the "rod-coil competitive mechanism" for the self-assembly of polymer brushes with rod-coil backbones. The results indicated that the micellar structures mainly depend on the relative intensity between the orientational ordering of rod blocks and the disordered packing of the flexible blocks. The cylindrical micelles were formed when the orientational order of the rod blocks predominates, while the disorder of the flexible blocks contributes to the formation of spherical micelles. We further proved that the competitive relationship is affected by polymer concentration, rod-block proportion and distribution of backbones and the grafting density of side chains. The increasing rod-block proportion, the rod-coil-rod backbones and the asymmetric grafting side chains are beneficial to the orientation order of the brush-like polymer in the self-assembly process, thereby inducing the formation of the cylindrical micelles. The self-assembly mechanism of the rod-coil copolymer proposed in this study provides guidance and a theoretical basis for the design and regulation of novel and complex polymer aggregates.

Mesoscopic simulations of drug-loaded diselenide crosslinked micelles: Stability, drug loading and release properties.

Intelligent reversible crosslinked micelles that have a good balance of structure stability in normal tissue and controlled drug release responded to the tumor microenvironment are highly promising novel drug delivery systems. However, to date, there have been very few reports about mesoscale simulations of drug-loaded polymeric reversible crosslinked micelles. Here, dissipative particle dynamics (DPD) simulation, the nearest-neighbor bonding principle, and the nearest media-bead bond breaking principle were used to investigate the influence of physiological environment along with low tumor pH and reduction microenvironment on the stability and doxorubicin (DOX) distribution of the star polymer [PCL-b-P(HEMA-Se-Se˜)-b-PPEGMA]6 diselenide crosslinked micelles with different diselenide crosslinking levels (CLs). The self-assembly process results obtained by DPD simulations reveal the formation of three-layer spherical micelles with the loaded DOX mainly distributed at the interfacial regions of the inner PCL core and middle HEMA layer. The structural stability and DOX loading capacity of the micelles can be improved by appropriately increasing the CL based on the nearest-neighbor bonding principle due to the effect of the pressure exerted by the crosslink that squeezes the loaded drugs from the intermediate and interfacial layers into the micelle core. Furthermore, the effect of breaking of the diselenide bond on the drug release properties was investigated through the use of the nearest media-bead bond breaking principle. A low CL gives rise to intense drug release, increasing the toxic side effects on the system. With the increase in the CL, the micelles show the transformation from local crosslinking to compact crosslinking, leading to slower drug release. Therefore, this work can provide some guidance on the mesoscale for the structural design and controlled construction of reversible crosslinked micelles for smart drug delivery systems.

Effect of Degree of Silicification on Silica/Silicic Acid Binding Cd(II) and Its Mechanism.

Heavy metal pollution in farmland soil reduces crop yield and quality and also potentially causes the crisis to human health. Formerly, the fact that silicon fertilizer could effectively reduce the residual concentration of heavy metal in crops has been identified at the tissue level. In this paper, molecular dynamics simulation was employed to investigate the effects of the degree of silicification of silicic acids [namely, the molar ratio of Si(OH)4 and SiO2] on the Cd(II) bound in the aspect of radial distribution functions and mean square displacements. The results demonstrated that Si(OH)4 attracted Cd(II) through the coordination, while SiO2 attracted Cd(II) by the adsorption. In particular, when the degree of silicification was 0, both the bound Cd(II) amount and strength were the maximum value, indicating that the silicon fertilizer had the best efficiency of Cd(II) bound as Si(OH)4. By comparing the adsorption energy and electronic transfer of Cd(II) and Si(OH)4 adsorption onto the SiO2 surface through the quantum chemical simulation, we concluded that Cd(II) adsorption onto the SiO2 surface was chemisorption, while the Si(OH)4 adsorption onto SiO2 surface was physisorption. Consequently, the adsorption capacity of Cd(II) on the SiO2 surface was higher than that of Si(OH)4 adsorption on the SiO2 surface. Moreover, the compact hydration layers around Cd(II) prevented the process of Cd(II) adsorption on the SiO2 surface; even so, the counterion Cl- in the system promoted the adsorption process. The mechanism of silicon fertilizer binding heavy metal Cd(II) was investigated and revealed at the molecular and electronic level. This work has expanded the possibility of theoretical guidance for the design of silicon fertilizer.

A multi-functional-group modified cellulose for enhanced heavy metal cadmium adsorption: Performance and quantum chemical mechanism.

Heavy metal contamination directly threatened human life and health. In this work, a novel carboxyl, amide, carbonyl sulfide and secondary amino group grafted cellulose derivative adsorbent (modified-cellulose) was prepared in an attempt to remove heavy metal Cd2+. The XRD, FTIR, 13C NMR and XPS results showed that the carboxyl, amide, carbonyl sulfide and secondary amino group were grafted onto the cellulose backbone successfully. Effects of various factors on the adsorption performance were investigated as well as the adsorption mechanism. The Cd2+ adsorption capacity of modified-cellulose was pretty good, up to 401.1 mg/g and with 3 times enhancement. The adsorption process was spontaneous, well described by the Freundlich model (R2 = 0.994), confirmed to the pseudo-second-order model (R2 > 0.997), and mainly controlled by chemisorption. The density functional theory (DFT) calculations indicating that the Cd2+ binding ability of multi-functional groups modified cellulose was stronger than that of single-functional group modified cellulose. The preferential adsorption sites were analyzed based on the frontier orbital theory (FOT), and they were concentrated on the secondary amino groups and carbonyl sulfides. It is foreseeable that the as-prepared modified-cellulose adsorbent has great potential in heavy metal cadmium removal, and our conclusions could provide significant theoretical guidance in the due bioresource utilization.

Enhanced stability of crosslinked and charged unimolecular micelles from multigeometry triblock copolymers with short hydrophilic segments: dissipative particle dynamics simulation.

High micellar stability and well-performed drug loading and release are two conflicting factors for unimolecular micelles as an ideal drug delivery system. Achieving the formation of unimolecular micelles with short hydrophilic blocks is a challenging and promising approach to solve this bottleneck and limitation of current unimolecular micelle systems. In this work, dissipative particle dynamics (DPD) simulation is used to study the synergetic effect of crosslinking and electrostatic repulsion on stability of unimolecular micelles and to analyze the micro-mechanism and factors influencing this synergetic stabilization strategy. The strategy can generate unimolecular micelles with extremely high stability for various supramolecular polymers with short hydrophilic chains. Protonation of DEAEMA blocks leads to a large improvement in micellar hydrophilicity. The protonated middle layer further shrinks through crosslinking to produce the largest charge density, enlarging the electrostatic repulsion between colloidal particles. Additionally, the crosslinking and protonation treatment maximizes the extension degree of hydrophilic EO segments due to the increasing steric hindrance and poor compatibility between DEAHEMA and EO blocks. In this study, the relation between shrinkage degree of hydrophobic cores and stability of unimolecular micelles is first reported. The above-mentioned transition of micellar structures and properties results in the maximum degree of core shrinkage (Rg of MMA blocks) corresponding to the high stability of unimolecular micelles. Further study shows that the increasing cyclization degree, the mode of end cyclization, and the crosslinking and electrostatic repulsion of the middle layer all exert favorable effects on the stability of unimolecular micelles due to controlled shrinkage of hydrophobic cores.

Quantitative Structure-Property Relationship for pH-Triggered Drug Release Performance of Acid-Responsive Four/Six-Arms Star Polymeric Micelles.

PURPOSE: The pH-responsive copolymer micelles are widely used as carriers in drug delivery system, but there are few micro-level mechanistically explorations on the pH-triggered drug release. Here we elucidate the relationship between drug release behavior of four/six-arms star copolymer micelles and the copolymer structures. METHOD: The net cumulative drug release percentage (En) was taken as the dependent variables, block unit autocorrelation descriptors as independent variables. The quantitative structure-property relationship models of drug release from block copolymers were developed at pH 7.4 and 5.0 of two periods (stage I: 0~12 h, stage II: 12~96 h). RESULTS: The models built are of good fitting ability, internal predictive ability, stability and statistically significance. Drug diffusion is mainly influenced by the intra-block force, and micellar erosion by inter-block force. At pH 5.0, lowest unoccupied molecular orbital energy of copolymer unit is the main factor influencing the En. Stage I of drug release is affected by hydrophobic property and stage II by regional polar of copolymer molecules. CONCLUSION: The models present good performance, factors affecting drug release behavior at different pH conditions can offer guidance for the design of copolymer structures to control the drug release behavior of micelles in a targeted and quantitatively way.

Systematic design and application of unimolecular star-like block copolymer micelles: a coarse-grained simulation study.

Unimolecular polymeric micelles have several features, such as thermodynamic stability, small particle size, biocompatibility, and the ability to internalize hydrophobic molecules. These micelles have recently attracted significant attention in various applications, such as nano-reactors, catalysis, and drug delivery. However, few attempts have explored the formation mechanisms and conditions of unimolecular micelles due to limited experimental techniques. In this study, a unimolecular micelle system formed from ß-cyclodextrin-graft-{poly(lactide)-block-poly(2-(dimethylamino) ethyl multimethacrylate)-block-poly[oligo (2-ethyl-2-oxazoline) methacrylate]} ß-CD-g-(PLA-b-PDMAEMA-b-PEtOxMA) star-like block copolymers in aqueous media was investigated by dissipative particle dynamics (DPD) to explore the formation process of unimolecular micelles. The simulation results showed that using longer hydrophobic or pH-sensitive chains, shorter hydrophilic backbones, smaller hydrophilic side chain grafting density, and fewer polymer arms resulted in micellar aggregation. Furthermore, this unimolecular polymeric micelle could be used for encapsulating gold nanoparticles, whose mesoscopic structure was also explored. The gold nanoparticles tended to distribute in the middle layer formed by PDMAEMA, and the unimolecular micelles were capable of impeding gold nanoparticle aggregation. This study could help understand the formation mechanism of unimolecular micelles formed from star-like block copolymers in dilute solutions and offer a theoretical guide to the design and preparation of promising unimolecular polymeric micelles with targeting properties.