Exploration of immune-modulatory effects of amivantamab in combination with pembrolizumab in lung and head and neck squamous cell carcinoma.

Immune checkpoint inhibitors are effective first-line therapy for solid cancers. However, low response rate and acquired resistance over time has led to the need for additional therapeutic options. Here, we evaluated synergistic anti-tumor efficacy of EGFR x MET targeting bispecific antibody, amivantamab with PD-L1 immunotherapy, pembrolizumab in head and neck squamous cell carcinoma (HNSCC) and lung squamous cell carcinoma (LUSC) tumor bearing humanized PDX models. We demonstrated that pembrolizumab or amivantamab alone was ineffective and that combination treatment induced a significant reduction of tumor growth in both models (p<0.0001 and p<0.01, respectively). It appeared that combination of amivantamab and pembrolizumab significantly enhanced infiltration of granzyme B-producing CD8 T cells was in the TME of HNSCC PDX (p<0.01), and enhanced neoantigen-associated central memory CD8 T cells in circulating immune cells. Analysis of single cell RNA transcriptomics suggested that the tumor cells dramatically upregulated EGFR and MET in response to PD-L1 immunotherapy, potentially creating a metabolic state fit for tumor persistence in the tumor microenvironment (TME) and rendered pembrolizumab ineffective. We demonstrated that EGFRHIGHMETHIGH subcluster displayed an increased expression of genes implicated in production of lactate (SLC16A3 and LDHA) compared to the EGFRLOWMETLOW cluster. Accumulation of lactate in the TME has been associated with immunosuppression by hindering the infiltration of tumor killing CD8 T and NK cells. This study proved that amivantamab reduced glycolytic markers in the EGFRHIGHMETHIGH subcluster including SLC16A3 and LDHA and highlighted remodeling of the TME by combination treatment, providing rationale for additional therapy of amivantamab with PD-1 immunotherapy.

Combination of UHPLC-MS/MS with context-specific network and cheminformatic approaches for identifying bioactivities and active components of propolis.

Discovering new bioactivities and identifying active compounds of food materials are major fields of study in food science. However, the process commonly requires extensive experiments and can be technically challenging. In the current study, we employed network biology and cheminformatic approaches to predict new target diseases, active components, and related molecular mechanisms of propolis. Applying UHPLC-MS/MS analysis results of propolis to Context-Oriented Directed Associations (CODA) and Combination-Oriented Natural Product Database with Unified Terminology (COCONUT) systems indicated atopic dermatitis as a novel target disease. Experimental validation using cell- and human tissue-based models confirmed the therapeutic potential of propolis against atopic dermatitis. Moreover, we were able to find the major contributing compounds as well as their combinatorial effects responsible for the bioactivity of propolis. The CODA/COCONUT system also provided compound-associated genes explaining the underlying molecular mechanism of propolis. These results highlight the potential use of big data-driven network biological approaches to aid in analyzing the impact of food constituents at a systematic level.

Neural correlates in the development of and recovery from dysphagia after supratentorial stroke: A prospective tractography study.

BACKGROUND: Swallowing impairment after stroke may be related to the state of the corticobulbar tract (CBT), which is the motor projection fiber responsible for deglutition, but evidence is still lacking regarding which parameter could relate to poststroke swallowing recovery as measured by videofluroscope findings. This prospective study evaluated diffusion tensor imaging (DTI) parameters among dysphagic stroke patients compared with those of nondysphagia stroke patients and age-matched healthy subjects and followed swallowing recovery in dysphagic patients as assessed with the Modified Barium Swallow Impairment Profile (MBSImP©). METHODS: Diffusion tractography was performed in 69 subjects, consisting of 27 S patients with dysphagia, 18 healthy subjects and 24 S patients with no evidence of dysphagia. DTI was performed within 14 days of stroke onset. Follow-up DTI was performed in the dysphagic group at three months. The tract volume (TV) of the CBT and frontal operculum as determined by fractional anisotropy (FA) was compared among the 3 groups. Correlations of these parameters with initial dysphagia severity and swallowing parameters at baseline and 3 months postonset were assessed. RESULTS: All stroke patients showed lower CBT TV on the affected and unaffected sides than those in the control group, even in those who showed no evidence of clinical dysphagia. The dysphagia group showed a greater reduction in CBT TV on the affected side (P < 0.001). Receiver operating characteristic analysis showed that cutoff values of 4.1 cm3 for TV and 0.24 for FA from the affected side could classify dysphagia with good accuracy (AUC = 0.77, 0.75, respectively) and specificity levels. FA values in the unaffected frontal operculum showed a significant correlation (rho = -0.40, P = 0.02) with swallowing outcome as observed by the total scores of MBSImP©. In addition, these values proved to be significant variables to predict swallowing outcome in multiple regression analysis (R2 = 0.6317, adjR2 = 0.5815, F = 12.58, p < 0.001, AIC = 203.65). CONCLUSIONS: Even when clinical dysphagia is not apparent, individuals with a supratentorial stroke may show reduced CBT parameters compared to healthy controls. Supratentorial stroke may manifest with dysphagia if a certain extent of CBT volume and white matter tract integrity is involved, with a greater degree of CBT injury in the affected sides determining poststroke dysphagia severity. In contrast, recovery was independent of the affected parameters, and an initial lower FA value in the unaffected frontal operculum was indicative of a poorer 3-month dysphagia outcome. DTI parameters obtained within two weeks of stroke onset may help classify those with dysphagia, predict recovery and help plain therapeutic strategies to maintain the adaptive role of the white matter tract, which is crucial in swallowing recovery.

Continuous centrifugal microfluidics (CCM) isolates heterogeneous circulating tumor cells via full automation.

Understanding cancer heterogeneity is essential to finding diverse genetic mutations in metastatic cancers. Thus, it is critical to isolate all types of CTCs to identify accurate cancer information from patients. Moreover, full automation robustly capturing the full spectrum of CTCs is an urgent need for CTC diagnosis to be routine clinical practice. Methods: Here we report the full capture of heterogeneous CTC populations using fully automated, negative depletion-based continuous centrifugal microfluidics (CCM). Results: The CCM system demonstrated high performance (recovery rates exceeding 90% and WBC depletion rate of 99.9%) across a wide range of phenotypes (EpCAM(+), EpCAM(-), small-, large-sized, and cluster) and cancers (lung, breast, and bladder). Applied in 30 lung adenocarcinoma patients harboring epidermal growth factor receptor (EGFR) mutations, the system isolated diverse phenotypes of CTCs in marker expression and size, implying the importance of unbiased isolation. Genetic analyses of intra-patient samples comparing cell-free DNA with CCM-isolated CTCs yielded perfect concordance, and CTC enumeration using our technique was correlated with clinical progression as well as response to EGFR inhibitors. Conclusion: Our system also introduces technical advances which assure rapid, reliable, and reproducible results, thus enabling a more comprehensive application of robust CTC analysis in clinical practice.

Bioreducible polymer-mediated delivery of oncolytic adenovirus can attenuate antiviral immune response and concurrently enhance the induction of antitumor immune response to effectively prevent metastasis.

Oncolytic virotherapy is a highly promising and novel treatment modality for cancer. Several clinical trials with oncolytic viruses have illustrated that the potent antitumor efficacy of these viruses may rely on the efficient induction of antitumor immune response. In contrast, antiviral immune response is attributed to adverse side defects and diminishing therapeutic efficacy. In the present report, we generated a nanohybrid complex incorporating immune stimulatory oncolytic adenovirus (oAd) co-expressing decorin (DCN) and interleukin (IL)-12 with a bioreducible nanomaterial composed of PEI-Arg-mPEG-S-S-mPEG-Arg-PEI blocks (PAPS), ultimately aiming to modulate both antitumor and antiviral immune responses to be favorable toward oncolytic virotherapy. The transduction efficacy of the PAPS-incorporated nanohybrid vector (Ad/PAPS) was significantly higher than that of a complex using our previously reported polymer PPSA (Ad/PPSA) regardless of the cellular coxsackievirus and adenovirus receptor expression level of cancer cells. oAd complexed with PAPS (oAd/PAPS) also elicited a more potent cancer cell killing effect, antitumor efficacy, and metastasis inhibition than naked oAd or oAd complexed with PPSA (oAd/PPSA) through a higher level of therapeutic transgenes (DCN and IL-12), viral replication, and more efficient infiltration of T cells into tumor tissues. Notably, oAd/PAPS induced the highest level of antitumor immune response while the antiviral immune response was mediated at a significantly lower level than those of naked oAd. Adaptive immune response against the virus was also significantly attenuated in the oAd/PAPS group. oAd/PAPS treatment also led to the highest level of antitumor central memory T cells and the lowest level of immunosuppressive regulatory T cells in the spleen. Collectively, our findings illustrate that oAd/PAPS can simultaneously regulate both antitumor and antiviral immune responses to be more favorable to oncolytic virotherapy, leading to improved gene expression, viral replication, and growth inhibition of both primary and metastatic tumors.

Role of Catechol-O-methyltransferase Val158Met Polymorphism on Transcranial Direct Current Stimulation in Swallowing.

Transcranial direct current stimulation (tDCS) is one of the latest post-stroke dysphagia treatment modalities, and the effect of tDCS is known to be affected by various factors including genetic polymorphisms. However, the role of catechol-O-methyltransferase (COMT) polymorphisms on tDCS in swallowing is unclear. In this prospective pilot study, we aim to explore the effect of tDCS on the swallowing cortex and subsequent swallowing motor function according to COMT polymorphism. Twenty-four healthy participants received either anodal tDCS or sham mode tDCS on the mylohyoid motor cortex at random order, after inhibitory repetitive transcranial magnetic stimulation (rTMS) for preconditioning. The primary outcome was the changes of mylohyoid-motor-evoked potentials (MH-MEP) amplitude in each COMT polymorphism group, from the post-inhibitory rTMS baseline state to immediate, 30, and 60 min after tDCS. The secondary outcomes were the changes in swallowing function. The results showed that COMT Val/Val polymorphism showed improvement across time in the MH-MEP amplitudes and triggering time of swallowing after tDCS, whereas COMT Met carrier group did not show significant changes of MH-MEP or swallowing function across time. This therapeutic response variability of tDCS in the mylohyoid motor system according to COMT polymorphism support the importance of genetic analysis in individualized dysphagia treatment.

High-Precision RTT-Based Indoor Positioning System Using RCDN and RPN.

Wi-Fi round-trip timing (RTT) was applied to indoor positioning systems based on distance estimation. RTT has a higher reception instability than the received signal strength indicator (RSSI)-based fingerprint in non-line-of-sight (NLOS) environments with many obstacles, resulting in large positioning errors due to multipath fading. To solve these problems, in this paper, we propose high-precision RTT-based indoor positioning system using an RTT compensation distance network (RCDN) and a region proposal network (RPN). The proposed method consists of a CNN-based RCDN for improving the prediction accuracy and learning rate of the received distances and a recurrent neural network-based RPN for real-time positioning, implemented in an end-to-end manner. The proposed RCDN collects and corrects a stable and reliable distance prediction value from each RTT transmitter by applying a scanning step to increase the reception rate of the TOF-based RTT with unstable reception. In addition, the user location is derived using the fingerprint-based location determination method through the RPN in which division processing is applied to the distances of the RTT corrected in the RCDN using the characteristics of the fast-sampling period.

Identification of prognostic mRNAs in metastatic cutaneous melanoma.

Cutaneous melanoma is the most common cause of skin cancer-related deaths worldwide. There is an urgent need to identify prognostic biomarkers to facilitate decision-making for treatment of metastatic cutaneous melanoma. Gene expression microarrays and RNA-seq technology have recently improved or changed current prognostic and therapeutic strategies for several cancers. However, according to the current melanoma staging system, prognosis is almost entirely dependent on clinicopathological features. To identify novel prognostic biomarkers, we investigated gene expression and clinical data for patients with cutaneous melanoma from three cohorts of The Cancer Genome Atlas and Gene Expression Omnibus. Kaplan-Meier survival analysis using median values of each gene as cutoff value revealed that nine genes (ABCC3, CAPS2, CCR6, CDCA8, CLU, DPF1, PTK2B, SATB1, and SYNE1) were statistically significant prognostic biomarkers of metastatic cutaneous melanoma in all three independent cohorts. Low expression of two genes (CDCA8 and DPF1) and high expression of seven genes (ABCC3, CAPS2, CCR6, CLU, PTK2B, SATB1, and SYNE) were significantly associated with positive metastatic cutaneous melanoma prognoses. In conclusion, we suggest nine novel prognostic biomarkers for cutaneous metastatic melanoma.

A User-Friendly, Web-Based Integrative Tool (ESurv) for Survival Analysis: Development and Validation Study.

BACKGROUND: Prognostic genes or gene signatures have been widely used to predict patient survival and aid in making decisions pertaining to therapeutic actions. Although some web-based survival analysis tools have been developed, they have several limitations. OBJECTIVE: Taking these limitations into account, we developed ESurv (Easy, Effective, and Excellent Survival analysis tool), a web-based tool that can perform advanced survival analyses using user-derived data or data from The Cancer Genome Atlas (TCGA). Users can conduct univariate analyses and grouped variable selections using multiomics data from TCGA. METHODS: We used R to code survival analyses based on multiomics data from TCGA. To perform these analyses, we excluded patients and genes that had insufficient information. Clinical variables were classified as 0 and 1 when there were two categories (for example, chemotherapy: no or yes), and dummy variables were used where features had 3 or more outcomes (for example, with respect to laterality: right, left, or bilateral). RESULTS: Through univariate analyses, ESurv can identify the prognostic significance for single genes using the survival curve (median or optimal cutoff), area under the curve (AUC) with C statistics, and receiver operating characteristics (ROC). Users can obtain prognostic variable signatures based on multiomics data from clinical variables or grouped variable selections (lasso, elastic net regularization, and network-regularized high-dimensional Cox-regression) and select the same outputs as above. In addition, users can create custom gene signatures for specific cancers using various genes of interest. One of the most important functions of ESurv is that users can perform all survival analyses using their own data. CONCLUSIONS: Using advanced statistical techniques suitable for high-dimensional data, including genetic data, and integrated survival analysis, ESurv overcomes the limitations of previous web-based tools and will help biomedical researchers easily perform complex survival analyses.

Antitumor Activity of Amivantamab (JNJ-61186372), an EGFR-MET Bispecific Antibody, in Diverse Models of EGFR Exon 20 Insertion-Driven NSCLC.

EGFR exon 20 insertion driver mutations (Exon20ins) in non-small cell lung cancer (NSCLC) are insensitive to EGFR tyrosine kinase inhibitors (TKI). Amivantamab (JNJ-61186372), a bispecific antibody targeting EGFR-MET, has shown preclinical activity in TKI-sensitive EGFR-mutated NSCLC models and in an ongoing first-in-human study in patients with advanced NSCLC. However, the activity of amivantamab in Exon20ins-driven tumors has not yet been described. Ba/F3 cells and patient-derived cells/organoids/xenograft models harboring diverse Exon20ins were used to characterize the antitumor mechanism of amivantamab. Amivantamab inhibited proliferation by effectively downmodulating EGFR-MET levels and inducing immune-directed antitumor activity with increased IFNγ secretion in various models. Importantly, in vivo efficacy of amivantamab was superior to cetuximab or poziotinib, an experimental Exon20ins-targeted TKI. Amivantamab produced robust tumor responses in two Exon20ins patients, highlighting the important translational nature of this preclinical work. These findings provide mechanistic insight into the activity of amivantamab and support its continued clinical development in Exon20ins patients, an area of high unmet medical need. SIGNIFICANCE: Currently, there are no approved targeted therapies for EGFR Exon20ins-driven NSCLC. Preclinical data shown here, together with promising clinical activity in an ongoing phase I study, strongly support further clinical investigation of amivantamab in EGFR Exon20ins-driven NSCLC.This article is highlighted in the In This Issue feature, p. 1079.

A Helical Polypeptide-Based Potassium Ionophore Induces Endoplasmic Reticulum Stress-Mediated Apoptosis by Perturbing Ion Homeostasis.

Perturbation of potassium homeostasis can affect various cell functions and lead to the onset of programmed cell death. Although ionophores have been intensively used as an ion homeostasis disturber, the mechanisms of cell death are unclear and the bioapplicability is limited. In this study, helical polypeptide-based potassium ionophores are developed to induce endoplasmic reticulum (ER) stress-mediated apoptosis. The polypeptide-based potassium ionophores disturb ion homeostasis and then induce prolonged ER stress in the cells. The ER stress results in oxidative environments that accelerate the activation of mitochondria-dependent apoptosis. Moreover, ER stress-mediated apoptosis is triggered in a tumor-bearing mouse model that suppresses tumor proliferation. This study provides the first evidence showing that helical polypeptide-based potassium ionophores trigger ER stress-mediated apoptosis by perturbation of potassium homeostasis.

Development of apoptosis-inducing polypeptide via simultaneous mitochondrial membrane disruption and Ca2+ delivery.

Mitochondria are the primary organelle of regulating apoptosis, and intracellular calcium ions are a key component of pro-apoptosis induction. Herein, we report an artificial apoptosis-inducing polypeptide that destabilizes the mitochondrial membrane and transports calcium ions into the cytosol, thereby synergistically creating severe oxidative conditions. The oxidative stress highly activates an apoptotic signaling cascade, and also inhibits cell migration and invasion in vitro and in vivo. The suggested strategy for simultaneous mitochondrial disruption and perturbed calcium homeostasis demonstrates the applicability of polypeptide-based therapeutics as potent apoptosis-inducers in cancer therapy.

Synergistic antitumor effect mediated by a paclitaxel-conjugated polymeric micelle-coated oncolytic adenovirus.

Combination treatment consisting of oncolytic adenovirus (Ad) and paclitaxel (PTX) is a promising strategy to achieve synergistic antitumor effect. However, a co-administration approach is subject to inherent limitations due to the poor solubility of PTX and chemoresistance of tumor cells. In order to overcome these limitations, an oncolytic Ad expressing a p53 variant (oAd-vp53) that is resistant to p53 inactivation in the tumor microenvironment was complexed with PEGylated and PTX-conjugated polymeric micelle (APP). This approach generated an oAd-vp53/APP complex (176.4 nm in diameter) that could concurrently deliver both oncolytic Ad and the nanoparticulate drug APP to tumors. APP-complexed replication-incompetent Ad (dAd/APP) exhibited 12-fold higher transduction efficiency than naked dAd in coxsackie adenovirus receptor (CAR)-negative cancer cells. This increased efficiency was attributed to more efficient cellular internalization mediated by charge interactions between APP and anionic cell membranes. Furthermore, oAd-vp53/APP elicited synergistically higher cancer cell killing than naked oAd-vp53, APP, or oAd-vp53 in combination with PTX (oAd-vp53 + PTX); this synergistic effect was shown to be due to superior induction of apoptosis and viral replication. Importantly, oAd-vp53/APP induced more potent and synergistic antitumor effect through both local and systemic administration by enhancing replication of oncolytic Ad and induction of apoptosis in tumor tissue. Further, the APP coating on the surface of Ad markedly attenuated the host immune response against Ad and decreased hepatic sequestration, resulting in minimal hepatotoxicity and a good safety profile. These attributes enabled oAd-vp53/APP to elicit potent antitumor effect over multiple treatment cycles. Altogether, we demonstrate that concurrent delivery of oncolytic Ad and APP as a single nanocomplex is a promising strategy for achieving synergistic antitumor effect.

Conformation-switchable helical polypeptide eliciting selective pro-apoptotic activity for cancer therapy.

Artificial cationic helical peptides possess an enhanced cell-penetrating property. However, their cell-penetrability is not converted by cellular environmental changes resulting in nonspecific uptake. In this study, pH-sensitive anion-donating groups were added to a helical polypeptide to simultaneously achieve tumor targeting and pro-apoptotic activity. The mitochondria-destabilizing helical polypeptide undergoing pH-dependent conformational transitions selectively targeted cancer cells consequently disrupting mitochondrial membranes and subsequently inducing apoptosis. This work presents a promising peptide therapeutic system for cancer therapy.

Enhanced anti-tumor efficacy and safety profile of tumor microenvironment-responsive oncolytic adenovirus nanocomplex by systemic administration.

Oncolytic adenovirus (Ad) holds great promise as a potential gene therapy for cancer. However, intravenously administered Ad may encounter difficulties due to unfavorable host responses, non-specific interactions, and the heterogeneity of the tumor cell population. As an approach to combine the advantages of oncolytic Ad and synthetic polymers and to address the associated difficulties, Ad was physically complexed with a pH-sensitive block copolymer, methoxy poly(ethylene glycol)-b-poly(l-histidine) (mPEG-b-pHis). The in vitro transduction efficiency at an acidic extracellular pH was remarkably enhanced in cancer cells when treated with the Ad expressing green fluorescent protein (GFP) coated with mPEG-b-pHis (c-dE1/GFP) as compared to that of naked Ad (n-dE1/GFP). Time-lapse total internal reflection fluorescence microscopic imaging revealed a significantly enhanced cellular uptake rate of c-dE1/GFP at acidic tumor pH when compared with that at neutral pH or naked cognate Ad (n-dE1/GFP). In addition, c-dE1/GFP remained relatively stable in human serum-containing media, and considerably reduced both the innate and adaptive immune response against Ad. Moreover, the therapeutic efficacy and survival benefit of mPEG-b-pHis-complexed oncolytic Ad (c-H5mT/Luc) by systemic treatment was significantly enhanced compared to that with naked oncolytic Ad (n-H5mT/Luc) in both coxsackie and adenovirus receptor-positive and -negative tumors. Whole-body bioluminescence imaging showed 7.3-fold higher luciferase expression at the tumor site and 23.0-fold less luciferase expression in liver tissue for c-H5mT/Luc relative to that for naked oncolytic Ad (n-H5mT/Luc). Considering the heterogeneity of tumor tissue, these results are important for guiding the development of more potent and specific treatment of devastating metastatic cancers using this viral system. STATEMENT OF SIGNIFICANCE: Although adenoviral systems have shown considerable promise and undergone extensive evaluation attempts to specifically target Ad vectors to cancer cells have met limited success. This shortcoming is due to the strong immune response stimulated by Ad and the hepatotoxicity of the viral particles. To overcome restricted vector issues, we generated Ad/mPEG-b-pHis for tumor microenvironment-targeting hybrid vector systems, an oncolytic Ad coated with a pH-responsive polymer, mPEG-b-pHis. The Ad/mPEG-b-pHis exhibited pH-dependent transduction efficiency and cancer-cell killing effects. Moreover, systemic administration of oncolytic Ad/mPEG-b-pHis led to marked suppression of tumor growth and tumor-specific viral replication. Ad successfully avoided the innate and adaptive immune responses and liver accumulation with the help of mPEG-b-pHis on its surface.

Safety profiles and antitumor efficacy of oncolytic adenovirus coated with bioreducible polymer in the treatment of a CAR negative tumor model.

Adenovirus (Ad) vectors show promise as cancer gene therapy delivery vehicles, but immunogenic safety concerns and coxsackie and adenovirus receptor (CAR)-dependency have limited their use. Alternately, biocompatible and bioreducible nonviral vectors, including arginine-grafted cationic polymers, have been shown to deliver nucleic acids through a cell penetration peptide (CPP) and protein transduction domain (PTD) effect. We utilized the advantages of both viral and nonviral vectors to develop a hybrid gene delivery vehicle by coating Ad with mPEG-PEI-g-Arg-S-S-Arg-g-PEI-mPEG (Ad/PPSA). Characterization of Ad/PPSA particle size and zeta potential showed an overall size and cationic charge increase in a polymer concentration-dependent manner. Ad/PPSA also showed a marked transduction efficiency increase in both CAR-negative and -positive cells compared to naked Ad. Competition assays demonstrated that Ad/PPSA produced higher transgene expression levels than naked Ad and achieved CAR-independent transduction. Oncolytic Ad (DWP418)/PPSA was able to overcome the nonspecificity of polymer-only therapies by demonstrating cancer-specific killing effects. Furthermore, the DWP418/PPSA nanocomplex elicited a 2.24-fold greater antitumor efficacy than naked Ad in vivo. This was supported by immunohistochemical confirmation of Ad E1As accumulation in MCF7 xenografted tumors. Lastly, intravenous injection of DWP418/PPSA elicited less innate immune response compared to naked Ad, evaluated by interleukin-6 cytokine release into the serum. The increased antitumor effect and improved vector targeting to both CAR-negative and -positive cells make DWP418/PPSA a promising tool for cancer gene therapy.

NDRG2 controls COX-2/PGE2-mediated breast cancer cell migration and invasion.

N-myc downstream-regulated gene 2 (NDRG2), which is known to have tumor suppressor functions, is frequently down-regulated in breast cancers and potentially involved in preventing the migration and invasion of malignant tumor cells. In the present study, we examined the inhibitory effects of NDRG2 overexpression, specifically focusing on the role of cyclooxygenase-2 (COX-2) in the migration of breast cancer cells. NDRG2 overexpression in MDA-MB-231 cells inhibited the expression of the COX-2 mRNA and protein, the transcriptional activity of COX-2, and prostaglandin E2 (PGE2) production, which were induced by a treatment with phorbol-12-myristate-13-acetate (PMA). Nuclear transcription factor-κB (NF-κB) signaling attenuated by NDRG2 expression resulted in a decrease in PMA-induced COX-2 expression. Interestingly, the inhibition of COX-2 strongly suppressed PMA-stimulated migration and invasion in MDA-MB-231-NDRG2 cells. Moreover, siRNA-mediated knockdown of NDRG2 in MCF7 cells increased the COX-2 mRNA and protein expression levels and the PMA-induced COX-2 expression levels. Consistent with these results, the migration and invasion of MCF7 cells treated with NDRG2 siRNA were significantly enhanced following treatment with PMA. Taken together, our data show that the inhibition of NF-κB signaling by NDRG2 expression is able to suppress cell migration and invasion through the down-regulation of COX-2 expression.

From covalent bonding to coalescence of metallic nanorods.

Growth of metallic nanorods by physical vapor deposition is a common practice, and the origin of their dimensions is a characteristic length scale that depends on the three-dimensional Ehrlich-Schwoebel (3D ES) barrier. For most metals, the 3D ES barrier is large so the characteristic length scale is on the order of 200 nm. Using density functional theory-based ab initio calculations, this paper reports that the 3D ES barrier of Al is small, making it infeasible to grow Al nanorods. By analyzing electron density distributions, this paper shows that the small barrier is the result of covalent bonding in Al. Beyond the infeasibility of growing Al nanorods by physical vapor deposition, the results of this paper suggest a new mechanism of controlling the 3D ES barrier and thereby nanorod growth. The modification of local degree of covalent bonding, for example, via the introduction of surfactants, can increase the 3D ES barrier and promote nanorod growth, or decrease the 3D ES barrier and promote thin film growth.

Diffusion and clustering of Au adatoms on H-terminated Si(111)-(1x1): A first principles study.

We have examined the diffusion and agglomeration of Au adatoms on the H-terminated Si(111)-(1x1) surface using periodic slab density functional theory calculations. We find that a single Au atom favorably resides atop a surface Si atom by breaking an original identical withSi-H bond while the H atom is bonded to the Au atom in the vertical direction, leading to the identical withSi-Au-H state. Starting from the most favorable on-top (T) site, a Au adatom is predicted to undergo diffusion by moving in and out of the T site without disrupting surface Si-H bonds. The predicted overall activation energy for the Au diffusion is 0.5 eV. Our calculations show that Au agglomeration leads to libration of H atoms from the Au/Si interface, while the H atoms are weakly bound to Au clusters and subsequently undergo associative H(2) desorption with no significant barrier. Based on charge density analysis we also discuss bonding mechanisms for Au on H-terminated Si(111)-(1x1). Our findings are as a whole consistent with experimental results available in literature.

Structure, energetics, and bonding of amorphous Au-Si alloys.

First principles periodic calculations based on gradient-corrected density functional theory have been performed to examine the structure, energetics, and bonding of amorphous Au-Si alloys with varying Au:Si composition ratios. Our results predict that the Au-Si alloy forms the most stable structure when the Si content is around 40-50 at. %, with an energy gain of about 0.15 eV/atom. In addition, the volume change per atom in the alloy exhibits a distinctive nonlinear trend, with the minimum value around 60 at. % Si. The occurrence of the minimum in the Au-Si mixing energy and volume is attributed to strong hybridization of the Au 5d-Si 3p states. We also present variations in the radial distribution function and atomic coordination number as a function of Au:Si composition ratio, with discussion of the nature of local packing and chemical bonding in the Au-Si alloy system.