beta1-Integrins induce phosphorylation of Akt on serine 473 independently of focal adhesion kinase and Src family kinases

Integrin αVβ3 mediates porcine deltacoronavirus infection and inflammatory response through activation of the FAK-PI3K-AKT-nf-κB signalling pathway

Porcine deltacoronavirus (PDCoV) is an emerging porcine enteropathogenic coronavirus that causes acute watery diarrhoea in piglets, resulting in significant economic losses to the global swine industry. However, the underlying mechanism of PDCoV infection is not well defined, which seriously hinders the development of effective drugs and vaccines. Integrins (ITG) are heterodimeric transmembrane glycoproteins that play important roles in the life cycle of many viruses. In the current study, the viral entry pathways of PDCoV were explored and the role of ITGαVβ3 was investigated during PDCoV infection. Our results showed that the lysosomal acidification inhibitor bafilomycin-A1 (Baf-A1) significantly reduced PDCoV infection, while exogenous protease facilitated PDCoV infection and even allowed PDCoV entry to bypass the endosomal pathway, suggesting PDCoV entry into cells via the endocytic pathway and the exogenous protease-mediated pathway simultaneously. Furthermore, ITGαVβ3 was identified to be involved in PDCoV infection, especially during viral entry stages. PDCoV infection triggers the activation of the focal adhesion kinase (FAK)-phosphatidylinositol 3-kinase (PI3K)-serine/threonine-specific protein kinase (AKT) signalling pathway, and this activation is ITGαVβ3-dependent, suggesting that the activation of the FAK-PI3K-AKT signalling pathway during PDCoV infection is mediated by ITGαVβ3. Our results further demonstrated that PDCoV infection induced the expression of inflammatory cytokines, which was mediated by activation of the ITGαVβ3-FAK-PI3K-AKT-nuclear transcription factor-κB (NF-κB) signalling pathway. Overall, the results revealed that ITGαVβ3 is an essential host factor for PDCoV infection and can serve as a supplementary receptor to facilitate PDCoV infection, which can help us to explore the molecular mechanism of PDCoV infection.

Acetyl-NPKY of integrin-β1 binds KINDLIN2 to control endothelial cell proliferation and junctional integrity

Integrin-dependent crosstalk between cell-matrix adhesions and cell-cell junctions is critical for controlling endothelial permeability and proliferation in cancer and inflammatory diseases but remains poorly understood. Here, we investigated how acetylation of the distal NPKY-motif of Integrin-β1 influences endothelial cell physiology and barrier function. Expression of an acetylation-mimetic β1-K794Q-GFP mutant led to the accumulation of immature cell-matrix adhesions accompanied by a transcriptomic reprograming of endothelial cells, involving genes associated with cell adhesion, proliferation, polarity, and barrier function. β1-K794Q-GFP induced constitutive MAPK signaling, junctional impairment, proliferation, and reduced contact inhibition at confluence. Structural analysis of Integrin-β1 interaction with KINDLIN2, biochemical pulldown assay, and binding energy determination by using molecular dynamics simulation showed that acetylation of K794 and the K794Q-mutant increased KINDLIN2 binding affinity to the Integrin-β1. Thus, enhanced recruitment of KINDLIN2 to Lysine-acetylated Integrin-β1 and resulting modulation of barrier function, offers new therapeutic possibilities for controlling vascular permeability and disease conditions.

Identification of β2 microglobulin, the product of B2M gene, as a Host Factor for Vaccinia Virus Infection by Genome-Wide CRISPR genetic screens

Genome-wide genetic screens are powerful tools to identify genes that act as host factors of viruses. We have applied this technique to analyze the infection of HeLa cells by Vaccinia virus, in an attempt to find genes necessary for infection. Infection of cell populations harboring single gene inactivations resulted in no surviving cells, suggesting that no single gene knock-out was able to provide complete resistance to Vaccinia virus and thus allow cells to survive infection. In the absence of an absolute infection blockage, we explored if some gene inactivations could provide partial protection leading to a reduced probability of infection. Multiple experiments using modified screening procedures involving replication restricted viruses led to the identification of multiple genes whose inactivation potentially increase resistance to infection and therefore cell survival. As expected, significant gene hits were related to proteins known to act in virus entry, such as ITGB1 and AXL as well as genes belonging to their downstream related pathways. Additionally, we consistently found β2-microglobulin, encoded by the B2M gene, among the screening top hits, a novel finding that was further explored. Inactivation of B2M resulted in 54% and 91% reduced VV infection efficiency in HeLa and HAP1 cell lines respectively. In the absence of B2M, while virus binding to the cells was unaffected, virus internalization and early gene expression were significantly diminished. These results point to β2-microglobulin as a relevant factor in the Vaccinia virus entry process.

The human ion channel TRPM2 modulates migration and invasion in neuroblastoma through regulation of integrin expression

Transient receptor potential channel TRPM2 is highly expressed in many cancers and involved in regulation of key physiological processes including mitochondrial function, bioenergetics, and oxidative stress. In Stage 4 non-MYCN amplified neuroblastoma patients, high TRPM2 expression is associated with worse outcome. Here, neuroblastoma cells with high TRPM2 expression demonstrated increased migration and invasion capability. RNA sequencing, RT-qPCR, and Western blotting demonstrated that the mechanism involved significantly greater expression of integrins α1, αv, β1, and β5 in cells with high TRPM2 expression. Transcription factors HIF-1α, E2F1, and FOXM1, which bind promoter/enhancer regions of these integrins, were increased in cells with high TRPM2 expression. Subcellular fractionation confirmed high levels of α1, αv, and β1 membrane localization and co-immunoprecipitation confirmed the presence of α1β1, αvβ1, and αvβ5 complexes. Inhibitors of α1β1, αvβ1, and αvβ5 complexes significantly reduced migration and invasion in cells highly expressing TRPM2, confirming their functional role. Increased pAkt^Ser473 and pERK^{Thr202/Tyr204}, which promote migration through mechanisms including integrin activation, were found in cells highly expressing TRPM2. TRPM2 promotes migration and invasion in neuroblastoma cells with high TRPM2 expression through modulation of integrins together with enhancing cell survival, negatively affecting patient outcome and providing rationale for TRPM2 inhibition in anti-neoplastic therapy.

Implications of fibrotic extracellular matrix in diabetic retinopathy

Fibrosis is an accumulation of extracellular matrix (ECM) proteins and fibers in a disordered fashion, which compromises cell and tissue functions. High glucose-induced fibrosis, a major pathophysiological change of diabetic retinopathy (DR), severely affects vision by compromising the retinal vasculature and ultimately disrupting retinal tissue organization. The retina is a highly vascularized, stratified tissue with multiple cell types organized into distinct layers. Chronically high blood glucose stimulates certain retinal cells to increase production and assembly of ECM proteins resulting in excess ECM deposition primarily in the capillary walls on the basal side of the endothelium. This subendothelial fibrosis of the capillaries is the earliest histological change in the diabetic retina and has been linked to the vascular dysfunction that underlies DR. Proteins that are not normally abundant in the capillary basement membrane (BM) matrix, such as the ECM protein fibronectin, are assembled in significant quantities, disrupting the architecture of the BM and altering its properties. Cell culture models have identified multiple mechanisms through which elevated glucose can stimulate fibronectin matrix assembly, including intracellular signaling pathways, alternative splicing, and non-enzymatic glycation of the ECM. The fibrotic subendothelial matrix alters cell adhesion and supports further accumulation of other ECM proteins leading to disruption of endothelial cell-cell junctions. We review evidence supporting the notion that these molecular changes in the ECM contribute to the pathogenesis of DR, including vascular leakage, loss of endothelial cells and pericytes, changes in blood flow, and neovascularization. We propose that the accumulation of ECM, especially fibronectin matrix, first around the vasculature and later in extravascular locations, plays a critical role in DR and vision loss. Strategies for DR prevention and treatment should consider the ECM a potential therapeutic target.

Cytokine Induced 3-D Organotypic Psoriasis Skin Model Demonstrates Distinct Roles for NF-κB and JAK Pathways in Disease Pathophysiology

Psoriasis vulgaris is an inflammatory skin disease that affects 2-3% of the population worldwide. One of the major challenges in discovering novel therapies is the poor translatability of animal models to human disease. Therefore, it is imperative to develop human preclinical models of psoriasis that are amenable to pharmacological intervention. Here we report a 3-D reconstituted human epidermis (RHE) culture system treated with cytokines commonly associated with psoriasis (TNFα, IL-17A and IL-22) that reproduced some key features of the human disease. The effects on epidermal morphology, gene transcription and cytokine production, which are dysregulated in psoriasis were assessed. Certain morphological features of psoriatic epidermis were evident in cytokine-stimulated RHEs, including hypogranulosis and parakeratosis. In addition, RHEs responded to a cytokine mix in a dose-dependent manner by expressing genes and proteins associated with impaired keratinocyte differentiation (keratin 10/K10, loricrin), innate immune responses (S100A7, DEFB4, elafin), and inflammation (IL-1α, IL-6, IL-8, IL-10, IL-12/23p40, IL-36γ, GM-CSF, and IFNγ) typical of psoriasis. These disease-relevant changes in morphology, gene transcription, and cytokine production were robustly attenuated by pharmacologically blocking TNFα/IL-17A-induced NF-κB activation with IKK-2 inhibitor IV. Conversely, inhibition of IL-22-induced JAK1 signaling with ABT-317 strongly attenuated morphological features of the disease but had no effect on NFκB-dependent cytokine production, suggesting distinct mechanisms of action by the cytokines driving psoriasis. These data support the use of cytokine-induced RHE models for identifying and targeting keratinocyte signaling pathways important for disease progression and may provide translational insights into novel keratinocyte mechanisms for novel psoriasis therapies.

Tetraspanins: Physiology, Colorectal Cancer Development, and Nanomediated Applications

Simple Summary

Considering the high incidence of colorectal cancer in adults, as well as the need for identifying novel therapies, we hereby explore the role of tetraspanins in the development of colorectal cancer. We have focused on variate aspects starting from the structure and general physiology and ending with the precise mechanisms involved in the dual reported role of tetraspanins (pro–tumoral and tumor suppressor key player element). Moreover, the present review focuses on the potential of tetraspanins as a target for nanotechnology-mediated therapies, also gathering the limited attempts towards this aim and their reported data.

Abstract

Tetraspanins are transmembrane proteins expressed in a multitude of cells throughout the organism. They contribute to many processes that surround cell–cell interactions and are associated with the progress of some diseases, including cancer. Their crucial role in cell physiology is often understated. Furthermore, recent studies have shown their great potential in being used as targeting molecules. Data have suggested the potential of tetraspanins as a targeting vector for nanomediated distribution and delivery for colorectal cancer applications. Our aim is to provide a review on the important part that tetraspanins play in the human organism and highlight their potential use for drug delivery systems using nanotechnology.

Desmoglein 3 contributes to tumorigenicity of pancreatic ductal adenocarcinoma through activating Src-FAK signaling

Desmogleins (DSGs), with the ability to link adjacent cells, have been shown to participate in the development of malignancy. DSG3 was up-regulated in various cancers, including lung, head and neck, and esophagus squamous cell carcinoma, which contributed to the tumor progression. The role of DSG3 in pancreatic ductal adenocarcinoma (PDAC) still remains elusive. Here, the expression of DSG3 was found to be enhanced in pancreatic cancer cell lines in vitro. Functional assays showed that shRNA-mediated knockdown of DSG3 decreased cell viability of pancreatic cancer cells and retarded the cell proliferation, migration and invasion. However, pcDNA-mediated over-expression of DSG3 exhibited reversed effect on pancreatic cancer cell progression. In addition, the in vivo assay demonstrated that transfection of shDSG3 lentiviruses into pancreatic cancer cells repressed the tumorigenicity of PDAC after the cancer cells were transplanted into mice subcutaneously. Elevated DSG3 expression promoted the phosphorylation of Src (p-Src), focal adhesion kinase (p-FAK) and AKT (p-AKT) in vitro, while silence of DSG3 reduced the expression of p-Src, p-FAK and p-AKT both in vitro and in vivo. In conclusion, DSG3, as an oncogene, contributed to the tumorigenicity of PDAC through activating Src-FAK signaling.

Artocarpin Targets Focal Adhesion Kinase-Dependent Epithelial to Mesenchymal Transition and Suppresses Migratory-Associated Integrins in Lung Cancer Cells

Focal adhesion kinase (FAK) controls several cancer aggressive potentials of cell movement and dissemination. As epithelial–mesenchymal transition (EMT) and the migratory-associated integrins, known influencers of metastasis, have been found to be linked with FAK activity, this study unraveled the potential pharmacological effect of artocarpin in targeting FAK resulting in the suppression of EMT and migratory behaviors of lung cancer cells. Treatment with artocarpin was applied at concentrations of 0–10 μM, and the results showed non-cytotoxicity in lung cancer cell lines (A549 and H460), normal lung (BEAS-2B) cells and primary metastatic lung cancer cells (ELC12, ELC16, and ELC20). We also found that artocarpin (0–10 µM) had no effect on cell viability, proliferation, and migration in BEAS-2B cells. For metastasis-related approaches, artocarpin significantly inhibited cell migration, invasion, and filopodia formation. Artocarpin also dramatically suppressed anchorage-independent growth, cancer stem cell (CSC) spheroid formation, and viability of CSC-rich spheroids. For molecular targets of artocarpin action, computational molecular docking revealed that artocarpin had the best binding affinity of −8.0 kcal/mol with FAK protein. Consistently, FAK-downstream proteins, namely active Akt (phosphorylated Akt), active mTOR (phosphorylated mTOR), and Cdc42, and EMT marker and transcription factor (N-cadherin, Vimentin, and Slug), were found to be significantly depleted in response to artocarpin treatment. Furthermore, we found the decrease of Caveolin-1 (Cav-1) accompanied by the reduction of integrin-αν and integrin-β3. Taken together, these findings support the anti-metastasis potentials of the compound to be further developed for cancer therapy.

Heparanase, cell signaling, and viral infections

Heparanase (HPSE) is a multifunctional protein endowed with many non-enzymatic functions and a unique enzymatic activity as an endo-β-D-glucuronidase. The latter allows it to serve as a key modulator of extracellular matrix (ECM) via a well-regulated cleavage of heparan sulfate side chains of proteoglycans at cell surfaces. The cleavage and associated changes at the ECM cause release of multiple signaling molecules with important cellular and pathological functions. New and emerging data suggest that both enzymatic as well as non-enzymatic functions of HPSE are important for health and illnesses including viral infections and virally induced cancers. This review summarizes recent findings on the roles of HPSE in activation, inhibition, or bioavailability of key signaling molecules such as AKT, VEGF, MAPK-ERK, and EGFR, which are known regulators of common viral infections in immune and non-immune cell types. Altogether, our review provides a unique overview of HPSE in cell-survival signaling pathways and how they relate to viral infections.

Development of highly functional bioengineered human liver with perfusable vasculature

Liver tissue engineering offers a promising strategy for liver failure patients. Since transplantation rejection resulting in vessel thrombosis is regarded as a major hurdle, vascular reconstruction is one of indispensable requirements of whole organ engineering. Here we demonstrated a novel strategy for reconstruction of a vascularized bioengineered human liver (VBHL) using decellularized liver scaffolds in an efficient manner. First we achieved fully functional endothelial coverage of scaffolds by adopting the anti-CD31 aptamer as a potent coating agent for re-endothelialization. Through an ex vivo human blood perfusion that recapitulates the blood coagulation response in humans, we demonstrated significantly reduced platelet aggregation in anti-CD31 aptamer coated scaffolds. We then produced VBHL constructs using liver parenchymal cells and nonparenchymal cells, properly organized into liver-like structures with an aligned vasculature. Interestingly, VBHL constructs displayed prominently enhanced long-term liver-specific functions that are affected by vascular functionality. The VBHL constructs formed perfusable vessel networks in vivo as evidenced by the direct vascular connection between the VBHL constructs and the renal circulation. Furthermore, heterotopic transplantation of VBHL constructs supported liver functions in a rat model of liver fibrosis. Overall, we proposed a new strategy to generate transplantable bioengineered livers characterized by highly functional vascular reconstruction.

LIGHT aggravates sepsis-associated acute kidney injury via TLR4-MyD88-NF-κB pathway

Sepsis‐associated acute kidney injury (SA‐AKI) is a common clinical critical care syndrome. It has received increasing attention due to its high morbidity and mortality; however, its pathophysiological mechanisms remain elusive. LIGHT, the 14th member of the tumour necrosis factor (TNF) superfamily and a bidirectional immunoregulatory molecule that regulates inflammation, plays a pivotal role in disease pathogenesis. In this study, mice with an intraperitoneal injection of LPS and HK‐2 cells challenged with LPS were employed as a model of SA‐AKI in vivo and in vitro, respectively. LIGHT deficiency notably attenuated kidney injury in pathological damage and renal function and markedly mitigated the inflammatory reaction by decreasing inflammatory mediator production and inflammatory cell infiltration in vivo. The TLR4‐Myd88‐NF‐κB signalling pathway in the kidney of LIGHT knockout mice was dramatically down‐regulated compared to the controls. Recombinant human LIGHT aggravated LPS‐treated HK‐2 cell injury by up‐regulating the expression of the TLR4‐Myd88‐NF‐κB signalling pathway and inflammation levels. TAK 242 (a selective TLR4 inhibitor) reduced this trend to some extent. In addition, blocking LIGHT with soluble receptor fusion proteins HVEM‐Fc or LTβR‐Fc in mice attenuated renal dysfunction and pathological damage in SA‐AKI. Our findings indicate that LIGHT aggravates inflammation and promotes kidney damage in LPS‐induced SA‐AKI via the TLR4‐Myd88‐NF‐κB signalling pathway, which provide potential strategies for the treatment of SA‐AKI.

Ketone Bodies Attenuate Wasting in Models of Atrophy

BACKGROUND

Cancer Anorexia Cachexia Syndrome (CACS) is a distinct atrophy disease negatively influencing multiple aspects of clinical care and patient quality of life. Although it directly causes 20% of all cancer-related deaths, there are currently no model systems that encompass the entire multifaceted syndrome, nor are there any effective therapeutic treatments.

METHODS

A novel model of systemic metastasis was evaluated for the comprehensive CACS (metastasis, skeletal muscle and adipose tissue wasting, inflammation, anorexia, anemia, elevated protein breakdown, hypoalbuminemia, and metabolic derangement) in both males and females. Ex vivo skeletal muscle analysis was utilized to determine ubiquitin proteasome degradation pathway activation. A novel ketone diester (R/S 1,3-Butanediol Acetoacetate Diester) was assessed in multifaceted catabolic environments to determine anti-atrophy efficacy.

RESULTS

Here, we show that the VM-M3 mouse model of systemic metastasis demonstrates a novel, immunocompetent, logistically feasible, repeatable phenotype with progressive tumor growth, spontaneous metastatic spread, and the full multifaceted CACS with sex dimorphisms across tissue wasting. We also demonstrate that the ubiquitin proteasome degradation pathway was significantly upregulated in association with reduced insulin-like growth factor-1/insulin and increased FOXO3a activation, but not tumor necrosis factor-α-induced nuclear factor-kappa B activation, driving skeletal muscle atrophy. Additionally, we show that R/S 1,3-Butanediol Acetoacetate Diester administration shifted systemic metabolism, attenuated tumor burden indices, reduced atrophy/catabolism and mitigated comorbid symptoms in both CACS and cancer-independent atrophy environments.

CONCLUSIONS

Our findings suggest the ketone diester attenuates multifactorial CACS skeletal muscle atrophy and inflammation-induced catabolism, demonstrating anti-catabolic effects of ketone bodies in multifactorial atrophy.

Primaquine phosphate induces the apoptosis of ATRA-resistant acute promyelocytic leukemia cells by inhibition of the NF-κB pathway

As a subtype of acute myeloid leukemia (AML), acute promyelocytic leukemia (APL) is characterized by a chromosomal translocation, most of which result in the production of a PML-RAR alpha fusion protein. Although the overall survival rate of APL patients has improved dramatically due to all-trans retinoic acid (ATRA) treatment, ATRA-resistance remains a clinical challenge in the management of APL. Therefore, alternative agents should be considered for ATRA-resistant APL patients. Here, we report that antimalaria drug primaquine phosphate (PRQ) exhibits an anti-leukemia effect on both ATRA-sensitive cell line NB4 and ATRA-resistant APL cell lines, NB4-LR2, NB4-LR1, and NB4-MR2. Moreover, PRQ significantly inhibited primary colony formation of untreated or relapsed APL patients. Further study showed that PRQ could induce the apoptosis of APL cells by inhibiting NF-κB signaling pathway. The in vivo study showed that PRQ significantly inhibited NB4-LR2 xenograft tumors growth. These results suggest that PRQ is a potential therapeutic agent for ATRA-resistant APL patients.

Corynebacterium tuberculostearicum, a human skin colonizer, induces the canonical nuclear factor-κB inflammatory signaling pathway in human skin cells

INTRODUCTION

Corynebacterium tuberculostearicum (C. t.) is a ubiquitous bacterium that colonizes human skin. In contrast to other members of the genus Corynebacterium, such as toxigenic Corynebacterium diphtheriae or the opportunistic pathogen Corynebacterium jeikeium, several studies suggest that C. t. may play a role in skin health and disease. However, the mechanisms underlying these effects remain poorly understood.

METHODS

To investigate whether C. t. induces inflammatory pathways in primary human epidermal keratinocytes (HEKs) and human cutaneous squamous carcinoma cells (SCCs), cell culture, reverse transcription-polymerase chain reaction (PCR), enzyme-linked immunosorbent assay, immunofluorescence microscopy, Western blot, chromatin immunoprecipitation-PCR, small interfering RNA knockdown and luciferase reporter expression system were used.

RESULTS

Herein, we demonstrate that C. t. upregulates the messenger RNA (mRNA) and protein levels of inflammatory mediators in two human skin cell lines, HEKs and SCCs. We further show activation of the canonical nuclear factor-κB (NF-κB) pathway in response to C. t. infection, including phosphorylation of the inhibitor of κB (IκB), the nuclear translocation of NF-κB subunit (NF-κB-P65 ) and the recruitment of NF-κB-P65 and RNA polymerase to the NF-κB response elements at the promoter region of the inflammatory genes. Lastly, the data confirm that C. t.-induced tumor necrosis factor mRNA expression in HEKs is toll-like receptor 2 (TLR2 ) dependent.

CONCLUSION

Our results offer a mechanistic model for C. t.-induced inflammation in human keratinocytes via TLR2 and activation of IκB kinase and downstream signaling through the canonical NF-κB pathway. Relevance to chronic inflammatory diseases of the skin and cutaneous oncology is discussed.

Schistosomal extracellular vesicle-enclosed miRNAs modulate host T helper cell differentiation

During the chronic stage of Schistosoma infection, the female lays fertile eggs, triggering a strong anti-parasitic type 2 helper T-cell (Th2) immune response. It is unclear how this Th2 response gradually declines even though the worms live for years and continue to produce eggs. Here, we show that Schistosoma mansoni downregulates Th2 differentiation in an antigen-presenting cell-independent manner, by modulating the Th2-specific transcriptional program. Adult schistosomes secrete miRNA-harboring extracellular vesicles that are internalized by Th cells in vitro. Schistosomal miRNAs are found also in T helper cells isolated from Peyer's patches and mesenteric lymph nodes of infected mice. In T helper cells, the schistosomal miR-10 targets MAP3K7 and consequently downmodulates NF-κB activity, a critical transcription factor for Th2 differentiation and function. Our results explain, at least partially, how schistosomes tune down the Th2 response, and provide further insight into the reciprocal geographic distribution between high prevalence of parasitic infections and immune disorders such as allergy. Furthermore, this worm-host crosstalk mechanism can be harnessed to develop diagnostic and therapeutic approaches for human schistosomiasis and Th2-associated diseases.

Role of GluN2A NMDA receptor in homocysteine-induced prostaglandin E2 release from neurons

Hyperhomocysteinemia or systemic elevation of homocysteine is a metabolic condition that has been linked to multiple neurological disorders where inflammation plays an important role in the progression of the disease. However, it is unclear whether hyperhomocysteinemia contributes to disease pathology by inducing an inflammatory response. The current study investigates whether exposure of primary cultures from rat and mice cortical neurons to high levels of homocysteine induces the expression and release of the proinflammatory prostanoid, Prostaglandin E2 (PGE2). Using enzymatic assays and immunoblot analysis we show concurrent increase in the activity of cytosolic phospholipase A2 (cPLA2) and level of cyclooxygenase-2 (COX2), two enzymes involved in PGE2 biosynthesis. The findings also show an increase in PGE2 release from neurons. Pharmacological inhibition of GluN2A-containing NMDAR (GluN2A-NMDAR) with NVP-AAM077 significantly reduces homocysteine-induced cPLA2 activity, COX2 expression, and subsequent PGE2 release. Whereas, inhibition of GluN2B-containing NMDAR (GluN2A-NMDAR) with Ro 25-6981 has no effect. Complementary studies in neuron cultures obtained from wild type and GluN2A knockout mice show that genetic deletion of GluN2A subunit of NMDAR attenuates homocysteine-induced neuronal increase in cPLA2 activity, COX2 expression, and PGE2 release. Pharmacological studies further establish the role of both extracellular-regulated kinase/mitogen-activated protein kinase and p38 MAPK in homocysteine-GluN2A NMDAR-dependent activation of cPLA2-COX2-PGE2 pathway. Collectively, these findings reveal a novel role of GluN2A-NMDAR in facilitating homocysteine-induced proinflammatory response in neurons.

Hypoxia inducible factor-1 promotes liver fibrosis in nonalcoholic fatty liver disease by activating PTEN/p65 signaling pathway

Obesity is a major contributor to the development of steatohepatitis and fibrosis from nonalcoholic fatty liver disease (NAFLD). Hypoxia aggravates progression of NAFLD. In mice on high-fat diet (HFD), hepatic steatosis leads to liver tissue hypoxia, evidenced by accumulation of hypoxia inducible factor-1-alpha (HIF-1α), which is a central regulator of the global response to hypoxia. Hepatocyte cell signaling is an important factor in hepatic fibrogenesis. We here hypothesize that HIF-1α knockout in hepatocyte may protect against liver fibrosis. We first found that HFD led to 80% more hepatic collagen deposition than Hif1a^-/- hep mice, which was confirmed by a-SMA staining of liver tissue. Body weight and liver weight were similar between groups. We then found the increasing HIF1a expression and decreasing PTEN expression in the mice on HFD and in PA-treated HepG2 cells. Finally, we found that HIF1 mediated PTEN/nfkb-p65 pathway plays an important role in the development of NAFLD to liver fibrosis. Collectively, these results identify a novel HIF1a/PTEN/NF-κ Bp65 signaling pathway in NAFLD, which could be targeted for the therapy.

ZINC4085554 inhibits cancer cell adhesion by interfering with the interaction of Akt1 and FAK

Perioperative or circulatory forces enhance disseminated cancer cell adhesiveness by modulating focal adhesion kinase (FAK)-Akt1 interaction. Selectively blocking FAK-Akt1 interaction by a peptide derived from the FAK-Four-point-one, ezrin, radixin, moesin (FERM) domain reduces colon cancer cell adhesion in vitro and in mice. A preliminary in silico screening identified two small molecules resembling a peptide that may inhibit pressure-stimulated SW620 cancer cell adhesion to collagen I. The present study selected ZINC4085554 for further study to validate its proposed mechanism of action, using human SW620 colon cancer cells as a model system. At 25 and 50 µM, ZINC4085554 inhibited the pressure-stimulated adhesion of SW620 colon cancer cells to collagen I. This molecule prevented pressure-stimulated FAK-Tyr-397 phosphorylation; however, it did not affect Akt1-Ser-473 phosphorylation, indicating that ZINC4085554 acts downstream of Akt1, while Akt-Thr-308 remains unchanged in the presence of pressure and or ZINC4085554. Indeed, ZINC4085554 inhibited FAK-Akt1 interaction in response to increased extracellular pressure, consistent with the proposed mechanism. ZINC4085554 did not inhibit FAK-Tyr-397 phosphorylation in response to cell adhesion to collagen I, indicating the specificity of the inhibitory effects towards force-stimulated pathways. Finally, the present study confirmed that ZINC4085554 at 50 µM prevented pressure-activation of adhesion to surgical wounds in vivo in parallel to its ablation of intracellular signaling. In summary, ZINC4085554 is a small molecule mimicking part of the structure of FAK that reduces cancer cell adhesion by impairing pressure-stimulated FAK-Akt1 interaction and its downstream consequences. ZINC4085554 does not inhibit conventional outside-in FAK signaling and may be less toxic than global FAK inhibitors, and ZINC4085554 may be an important step towards the inhibition of metastasis.

Annexin 1-nuclear factor-κB-microRNA-26a regulatory pathway in the metastasis of non-small cell lung cancer

Background

Annexin 1 (ANXA1) expression is associated with the malignant tumor phenotype, making it an attractive therapeutic target. However, little is known about the regulation of ANXA1 in non‐small cell lung cancer (NSCLC).

Methods

We investigated the biological roles of ANXA1 in tumor growth, migration, and invasion, and explored the possibility of ANXA1 as a potential therapeutic target for the treatment of NSCLC.

Results

Our findings revealed that ANXA1 enhanced nuclear factor (NF)‐κB activation in NSCLC cells by interaction with inhibitor of NF‐κB kinase complex subunit, IKKγ. We also found that NF‐κB could negatively regulate microRNA (miR)‐26a, and miR‐26a was regulated through the ANXA1–NF‐κB regulatory pathway. NF‐κB activation negatively regulated by miR‐26a was confirmed in NSCLC.

Conclusion

Together, these results provide evidence of the mechanisms of the ANXA1–NF‐κB–miR‐26a regulatory pathway in the invasion and migration in NSCLC.

The IκB kinase complex is a regulator of mRNA stability

The IκB kinase (IKK) is considered to control gene expression primarily through activation of the transcription factor NF-κB. However, we show here that IKK additionally regulates gene expression on post-transcriptional level. IKK interacted with several mRNA-binding proteins, including a Processing (P) body scaffold protein, termed enhancer of decapping 4 (EDC4). IKK bound to and phosphorylated EDC4 in a stimulus-sensitive manner, leading to co-recruitment of P body components, mRNA decapping proteins 1a and 2 (DCP1a and DCP2) and to an increase in P body numbers. Using RNA sequencing, we identified scores of transcripts whose stability was regulated via the IKK-EDC4 axis. Strikingly, in the absence of stimulus, IKK-EDC4 promoted destabilization of pro-inflammatory cytokines and regulators of apoptosis. Our findings expand the reach of IKK beyond its canonical role as a regulator of transcription.

Oxidative stress and inflammation in a spectrum of epileptogenic cortical malformations: molecular insights into their interdependence

Oxidative stress (OS) occurs in brains of patients with epilepsy and coincides with brain inflammation, and both phenomena contribute to seizure generation in animal models. We investigated whether expression of OS and brain inflammation markers co-occurred also in resected brain tissue of patients with epileptogenic cortical malformations: hemimegalencephaly (HME), focal cortical dysplasia (FCD) and cortical tubers in tuberous sclerosis complex (TSC). Moreover, we studied molecular mechanisms linking OS and inflammation in an in vitro model of neuronal function. Untangling interdependency and underlying molecular mechanisms might pose new therapeutic strategies for treating patients with drug-resistant epilepsy of different etiologies. Immunohistochemistry was performed for specific OS markers xCT and iNOS and brain inflammation markers TLR4, COX-2 and NF-κB in cortical tissue derived from patients with HME, FCD IIa, IIb and TSC. Additionally, we studied gene expression of these markers using the human neuronal cell line SH-SY5Y in which OS was induced using H₂ O₂ . OS markers were higher in dysmorphic neurons and balloon/giant cells in cortex of patients with FCD IIb or TSC. Expression of OS markers was positively correlated to expression of brain inflammation markers. In vitro, 100 µM, but not 50 µM, of H₂ O₂ increased expression of TLR4, IL-1β and COX-2. We found that NF-κB signaling was activated only upon stimulation with 100 µM H₂ O₂ leading to upregulation of TLR4 signaling and IL-1β. The NF-κB inhibitor TPCA-1 completely reversed this effect. Our results show that OS positively correlates with neuroinflammation and is particularly evident in brain tissue of patients with FCD IIb and TSC. In vitro, NF-κB is involved in the switch to an inflammatory state after OS. We propose that the extent of OS can predict the neuroinflammatory state of the brain. Additionally, antioxidant treatments may prevent the switch to inflammation in neurons thus targeting multiple epileptogenic processes at once.

TRUSS Exacerbates NAFLD Development by Promoting IκBα Degradation in Mice

There is no effective treatment method for nonalcoholic fatty liver disease (NAFLD), the most common liver disease. The exact mechanism underlying the pathogenesis of NAFLD remains to be elucidated. Here, we report that tumor necrosis factor receptor-associated ubiquitous scaffolding and signaling protein (TRUSS) acts as a positive regulator of NAFLD and in a variety of metabolic disorders. TRUSS expression was increased in the human liver specimens with NAFLD or nonalcoholic steatohepatitis, and in the livers of high-fat diet (HFD)-induced and genetically obese mice. Conditional knockout of TRUSS in hepatocytes significantly ameliorated hepatic steatosis, insulin resistance, glucose intolerance, and inflammatory responses in mice after HFD challenge or in spontaneous obese mice with normal chow feeding. All of these HFD-induced pathological phenotypes were exacerbated in mice overexpressing TRUSS in hepatocytes. We show that TRUSS physically interacts with the inhibitor of nuclear factor κB α (IκBα) and promotes the ubiquitination and degradation of IκBα, which leads to aberrant activation of nuclear factor κB (NF-κB). Overexpressing IκBα^S32A/S36A , a phosphorylation-resistant mutant of IκBα, in the hepatocyte-specific TRUSS overexpressing mice almost abolished HFD-induced NAFLD and metabolic disorders. Conclusion: Hepatocyte TRUSS promotes pathological stimuli-induced NAFLD and metabolic disorders, through activation of NF-κB by promoting ubiquitination and degradation of IκBα. Our findings may provide a strategy for the prevention and treatment of NAFLD by targeting TRUSS.

Avicequinone B sensitizes anoikis in human lung cancer cells

BACKGROUND

During metastasis, cancer cells require anokis resistant mechanism to survive until reach the distant secondary tissues. As anoikis sensitization may benefit for cancer therapy, this study demonstrated the potential of avicequinone B, a natural furanonaphthoquinone found in mangrove tree (Avicenniaceae) to sensitize anoikis in human lung cancer cells.

METHODS

Anoikis inducing effect was investigated in human lung cancer H460, H292 and H23 cells that were cultured in ultra-low attachment plate with non-cytotoxic concentrations of avicequinone B. Viability of detached cells was evaluated by XTT assay at 0-24 h of incubation time. Soft agar assay was performed to investigate the inhibitory effect of avicequinone B on anchorage-independent growth. The alteration of anoikis regulating molecules including survival and apoptosis proteins were elucidated by western blot analysis.

RESULTS

Avicequinone B at 4 μM significantly induced anoikis and inhibited proliferation under detachment condition in various human lung cancer cells. The reduction of anti-apoptotic proteins including anti-apoptotic protein B-cell lymphoma 2 (Bcl-2) and myeloid cell leukemia 1 (Mcl-1) associating with the diminution of integrin/focal adhesion kinase (FAK)/Proto-oncogene tyrosine-protein kinase (Src) signals were detected in avicequinone B-treated cells.

CONCLUSIONS

Avicequinone B sensitized anoikis in human lung cancer cells through down-regulation of anti-apoptosis proteins and integrin-mediated survival signaling.

Bioinformatic Integration of Molecular Networks and Major Pathways Involved in Mice Cochlear and Vestibular Supporting Cells

Background: Cochlear and vestibular epithelial non-hair cells (ENHCs) are the supporting elements of the cellular architecture in the organ of Corti and the vestibular neuroepithelium in the inner ear. Intercellular and cell-extracellular matrix interactions are essential to prevent an abnormal ion redistribution leading to hearing and vestibular loss. The aim of this study is to define the main pathways and molecular networks in the mouse ENHCs. Methods: We retrieved microarray and RNA-seq datasets from mouse epithelial sensory and non-sensory cells from gEAR portal (http://umgear.org/index.html) and obtained gene expression fold-change between ENHCs and non-epithelial cells (NECs) against HCs for each gene. Differentially expressed genes (DEG) with a log2 fold change between 1 and -1 were discarded. The remaining genes were selected to search for interactions using Ingenuity Pathway Analysis and STRING platform. Specific molecular networks for ENHCs in the cochlea and the vestibular organs were generated and significant pathways were identified. Results: Between 1723 and 1559 DEG were found in the mouse cochlear and vestibular tissues, respectively. Six main pathways showed enrichment in the supporting cells in both tissues: (1) "Inhibition of Matrix Metalloproteases"; (2) "Calcium Transport I"; (3) "Calcium Signaling"; (4) "Leukocyte Extravasation Signaling"; (5) "Signaling by Rho Family GTPases"; and (6) "Axonal Guidance Si". In the mouse cochlea, ENHCs showed a significant enrichment in 18 pathways highlighting "axonal guidance signaling (AGS)" (p = 4.37 × 10^-8) and "RhoGDI Signaling" (p = 3.31 × 10^-8). In the vestibular dataset, there were 20 enriched pathways in ENHCs, the most significant being "Leukocyte Extravasation Signaling" (p = 8.71 × 10^-6), "Signaling by Rho Family GTPases" (p = 1.20 × 10^-5) and "Calcium Signaling" (p = 1.20 × 10^-5). Among the top ranked networks, the most biologically significant network contained the "auditory and vestibular system development and function" terms. We also found 108 genes showing tonotopic gene expression in the cochlear ENHCs. Conclusions: We have predicted the main pathways and molecular networks for ENHCs in the organ of Corti and vestibular neuroepithelium. These pathways will facilitate the design of molecular maps to select novel candidate genes for hearing or vestibular loss to conduct functional studies.

Antimalarial drug mefloquine inhibits nuclear factor kappa B signaling and induces apoptosis in colorectal cancer cells

Nuclear factor kappa B (NF‐κB) signaling pathway is activated in many colorectal cancer (CRC) cells and in the tumor microenvironment, which plays a critical role in cancer initiation, development, and response to therapies. In the present study, we found that the widely used antimalarial drug mefloquine was a NF‐κB inhibitor that blocked the activation of IκBα kinase, leading to reduction of IκBα degradation, decrease of p65 phosphorylation, and suppressed expression of NF‐κB target genes in CRC cells. We also found that mefloquine induced growth arrest and apoptosis of CRC cells harboring phosphorylated p65 in culture and in mice. Furthermore, expression of constitutive active IKKβ kinase significantly attenuated the cytotoxic effect of the compound. These results showed that mefloquine could exert antitumor action through inhibiting the NF‐κB signaling pathway, and indicated that the antimalarial drug might be repurposed for anti‐CRC therapy in the clinic as a single agent or in combination with other anticancer drugs.

Constitutive Activation of Integrin α9 Augments Self-Directed Hyperplastic and Proinflammatory Properties of Fibroblast-like Synoviocytes of Rheumatoid Arthritis

Despite advances in the treatment of rheumatoid arthritis (RA), currently approved medications can have significant side effects due to their direct immunosuppressive activities. Additionally, current therapies do not address residual synovial inflammation. In this study, we evaluated the role of integrin α9 and its ligand, tenascin-C (Tn-C), on the proliferative and inflammatory response of fibroblast-like synoviocytes (FLSs) from RA patients grown in three-dimensional (3D)-micromass culture. FLSs from osteoarthritis patients, when grown in the 3D-culture system, formed self-directed lining-like structures, whereas FLSs from RA tissues (RA-FLSs) developed an abnormal structure of condensed cellular accumulation reflective of the pathogenic features of RA synovial tissues. Additionally, RA-FLSs grown in 3D culture showed autonomous production of proinflammatory mediators. Predominant expression of α9 and Tn-C was observed in the condensed lining, and knockdown of these molecules abrogated the abnormal lining-like structure formation and suppressed the spontaneous expression of matrix metalloproteinases, IL-6, TNFSF11/RANKL, and cadherin-11. Disruption of α9 also inhibited expression of Tn-C, suggesting existence of a positive feedback loop in which the engagement of α9 with Tn-C self-amplifies its own signaling and promotes progression of synovial hyperplasia. Depletion of α9 also suppressed the platelet-derived growth factor-induced hyperplastic response of RA-FLSs and blunted the TNF-α-induced expression of matrix metalloproteinases and IL-6. Finally, α9-blocking Ab also suppressed the formation of the condensed cellular lining by RA-FLSs in 3D cultures in a concentration-related manner. This study demonstrates the central role of α9 in pathogenic behaviors of RA-FLSs and highlights the potential of α9-blocking agents as a nonimmunosuppressive treatment for RA-associated synovitis.

α-Lipoic acid sensitizes lung cancer cells to chemotherapeutic agents and anoikis via integrin β1/β3 downregulation

Chemotherapeutic failure and metastasis are the main causes of high mortality rate in lung cancer. Alteration of cellular redox status in response to endogenous stimuli or exogenous compounds has a significant impact on cell signaling and behavior. Herein we divulge for the first time that lung cancer cells exposed to α-lipoic acid (LA) resulted in a higher level of cellular superoxide anion (O2·-) and hydrogen peroxide (H2O2), and such an increase of the specific reactive oxygen species (ROS) downregulated integrin β1 and β3, the integrins known for potentiating aggressive behavior and metastasis. The LA-treated cells exhibited significant decrease in their abilities to survive in detached condition and grow in anchorage-independent soft agar assay. Furthermore, LA sensitized the cells to cisplatin, etoposide and paclitaxel-induced apoptosis. For underlying mechanism, we found that the treatment of the cells with LA significantly decreased integrin β1 and β3, while had no effect on integrin α5 and αv. Interestingly, survival protein p-AKT and anti-apoptotic protein Bcl-2 were reduced in an association to such integrin modulations. Using ROS probes and selective anti-oxidants, we have shown that H2O2 and O2·- induced by LA are key players for the decrease of β1 and β3 integrins, respectively. These findings indicate a novel effect of LA as well as specific ROS, O2·- and H2O2 in integrin regulation, anoikis and chemotherapeutic sensitizations.

Induction of apoptosis by HBI-8000 in adult T-cell leukemia/lymphoma is associated with activation of Bim and NLRP3

Adult T‐cell leukemia/lymphoma (ATL) is an aggressive T‐cell malignancy caused by human T‐cell lymphotropic virus 1. Treatment options for acute ATL patients include chemotherapy, stem cell transplantation, and recently the anti‐chemokine (C‐C motif) receptor 4 antibody, although most patients still have a poor prognosis and there is a clear need for additional options. HBI‐8000 is a novel oral histone deacetylase inhibitor with proven efficacy for treatment of T‐cell lymphomas that recently received approval in China. In the present study, we evaluated the effects of HBI‐8000 on ATL‐derived cell lines and primary cells obtained from Japanese ATL patients. In most cases HBI‐8000 induced apoptosis in both primary ATL cells and cell lines. In addition, findings obtained with DNA microarray suggested Bim activation and, interestingly, the contribution of the NLR family, pyrin domain containing 3 (NLRP3) inflammasome pathway in HBI‐8000‐induced ATL cell death. Further investigations using siRNAs confirmed that Bim contributes to HBI‐8000‐induced apoptosis. Our results provide a rationale for a clinical investigation of the efficacy of HBI‐8000 in patients with ATL. Although the role of NLRP3 inflammasome activation in ATL cell death remains to be verified, HBI‐8000 may be part of a novel therapeutic strategy for cancer based on the NLRP3 pathway.

SPATA2 links CYLD to the TNF-α receptor signaling complex and modulates the receptor signaling outcomes

TNF-α is a key regulator of innate immune and proinflammatory responses. However, the composition of the TNF-α receptor-associated signaling complexes (TNF-RSC) and the architecture of the downstream signaling networks are incompletely understood. We employed quantitative mass spectrometry to demonstrate that TNF-α stimulation induces widespread protein phosphorylation and that the scope of phosphorylation expands in a temporal manner. TNF-α stimulation also induces rapid ubiquitylation of components of the TNF-RSC Temporal analysis of the TNF-RSC composition identified SPATA2 as a novel component of the TNF-RSC The predicted PUB domain in the N-terminus of SPATA2 interacts with the USP domain of CYLD, whereas the C-terminus of SPATA2 interacts with HOIP SPATA2 is required for recruitment of CYLD to the TNF-RSC Downregulation of SPATA2 augments transcriptional activation of NF-κB and inhibits TNF-α-induced necroptosis, pointing to an important function of SPATA2 in modulating the outcomes of TNF-α signaling. Taken together, our study draws a detailed map of TNF-α signaling, identifies SPATA2 as a novel component of TNF-α signaling, and provides a rich resource for further functional investigations.

Overexpression of miR-223 Tips the Balance of Pro- and Anti-hypertrophic Signaling Cascades toward Physiologic Cardiac Hypertrophy

MicroRNAs (miRNAs) have been extensively examined in pathological cardiac hypertrophy. However, few studies focused on profiling the miRNA alterations in physiological hypertrophic hearts. In this study we generated a transgenic mouse model with cardiac-specific overexpression of miR-223. Our results showed that elevation of miR-223 caused physiological cardiac hypertrophy with enhanced cardiac function but no fibrosis. Using the next generation RNA sequencing, we observed that most of dys-regulated genes (e.g. Atf3/5, Egr1/3, Sfrp2, Itgb1, Ndrg4, Akip1, Postn, Rxfp1, and Egln3) in miR-223-transgenic hearts were associated with cell growth, but they were not directly targeted by miR-223. Interestingly, these dys-regulated genes are known to regulate the Akt signaling pathway. We further identified that miR-223 directly interacted with 3'-UTRs of FBXW7 and Acvr2a, two negative regulators of the Akt signaling. However, we also validated that miR-223 directly inhibited the expression of IGF-1R and β1-integrin, two positive regulators of the Akt signaling. Lastly, Western blotting did reveal that Akt was activated in miR-223-overexpressing hearts. Adenovirus-mediated overexpression of miR-223 in neonatal rat cardiomyocytes induced cell hypertrophy, which was blocked by the addition of MK2206, a specific inhibitor of Akt Taken together, these data represent the first piece of work showing that miR-223 tips the balance of promotion and inactivation of Akt signaling cascades toward activation of Akt, a key regulator of physiological cardiac hypertrophy. Thus, our study suggests that the ultimate phenotype outcome of a miRNA may be decided by the secondary net effects of the whole target network rather than by several primary direct targets in an organ/tissue.

GABAB R/GSK-3β/NF-κB signaling pathway regulates the proliferation of colorectal cancer cells

Colorectal cancer is one of the leading causes of highly fatal cancer-related deaths in the whole world. Fast growth is critical characteristic of colorectal cancer, the underlying regulatory mechanism of colorectal cell fast proliferation remains largely unknown. Here, we reported that activation of metabotropic γ-Aminobutyric acid receptor (GABAB R) signaling significantly inhibited the colorectal cell HT29 proliferation by arresting the cell at G1 phase. Inhibition of GABAB R activated GSK-3β by reducing the phosphorylation level of GSK-3β. Activation of GSK-3β blocked the function of GABAB R signaling on repressing cell proliferation. We further found that GABAB R activation inhibited NF-κB activity. The promotion of cell proliferation caused by downregulation of GABRB R could be blocked by inhibition of NF-κB activation. Overall, activation of GABAB R leaded to inhibition of GSK-3β activation to repress the NF-κB function during colorectal cancer cell proliferation. This study revealed critical function of GABAB R/GSK-3β/NF-κB signaling pathway on regulating proliferation of colorectal cancer cell, which might provide a potential therapeutic target for clinical colorectal cancer treatment.

Loss of miR-200b promotes invasion via activating the Kindlin-2/integrin β1/AKT pathway in esophageal squamous cell carcinoma: An E-cadherin-independent mechanism

Our previous studies have shown that loss of miR-200b enhances the invasiveness of esophageal squamous cell carcinoma (ESCC) cells. However, whether the miR-200-ZEB1/2-E-cadherin regulatory cascade, a master regulator of epithelial-to-mesenchymal transition (EMT), is involved in the regulation of ESCC invasion remains elusive. Here, we show that miR-200b represses ESCC cell invasion in vivo without altering the expression of E-cadherin and vimentin, two surrogate markers of EMT. However, an inverse correlation was observed between the expression levels of miR-200b and ZEB1/2 in both ESCC cell lines (n = 7, P < 0.05) and ESCC tumor samples (n = 88, P < 0.05). Methylation of E-cadherin gene was found to block the regulation of E-cadherin by the miR-200b-ZEB1/2 axis, indicating that an E-cadherin-independent mechanism can mediate the biological function of miR-200b in ESCC. We revealed that miR-200b suppresses the integrin β1-AKT pathway via targeting Kindlin-2 to mitigate ESCC cell invasiveness. In two independent cohorts of ESCC samples (n = 20 and n = 53, respectively), Kindlin-2 expression positively correlated with the activation status of both the integrin signaling pathway and the PI3K-AKT signaling pathway (both P < 0.01). These data highlight that suppression of the Kindlin-2-integrin β1-AKT regulatory axis is an alternative mechanism underlying the tumor suppressor function of miR-200b in ESCC.

Tetraspanins as regulators of the tumour microenvironment: implications for metastasis and therapeutic strategies

One of the hallmarks of cancer is the ability to activate invasion and metastasis. Cancer morbidity and mortality are largely related to the spread of the primary, localized tumour to adjacent and distant sites. Appropriate management and treatment decisions based on predicting metastatic disease at the time of diagnosis is thus crucial, which supports better understanding of the metastatic process. There are components of metastasis that are common to all primary tumours: dissociation from the primary tumour mass, reorganization/remodelling of extracellular matrix, cell migration, recognition and movement through endothelial cells and the vascular circulation and lodgement and proliferation within ectopic stroma. One of the key and initial events is the increased ability of cancer cells to move, escaping the regulation of normal physiological control. The cellular cytoskeleton plays an important role in cancer cell motility and active cytoskeletal rearrangement can result in metastatic disease. This active change in cytoskeletal dynamics results in manipulation of plasma membrane and cellular balance between cellular adhesion and motility which in turn determines cancer cell movement. Members of the tetraspanin family of proteins play important roles in regulation of cancer cell migration and cancer-endothelial cell interactions, which are critical for cancer invasion and metastasis. Their involvements in active cytoskeletal dynamics, cancer metastasis and potential clinical application will be discussed in this review. In particular, the tetraspanin member, CD151, is highlighted for its major role in cancer invasion and metastasis.

LINKED ARTICLES

This article is part of a themed section on Cytoskeleton, Extracellular Matrix, Cell Migration, Wound Healing and Related Topics. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-24.

Repression of SRF target genes is critical for Myc-dependent apoptosis of epithelial cells

Oncogenic levels of Myc expression sensitize cells to multiple apoptotic stimuli, and this protects long-lived organisms from cancer development. How cells discriminate physiological from supraphysiological levels of Myc is largely unknown. Here, we show that induction of apoptosis by Myc in breast epithelial cells requires association of Myc with Miz1. Gene expression and ChIP-Sequencing experiments show that high levels of Myc invade target sites that lack consensus E-boxes in a complex with Miz1 and repress transcription. Myc/Miz1-repressed genes encode proteins involved in cell adhesion and migration and include several integrins. Promoters of repressed genes are enriched for binding sites of the serum-response factor (SRF). Restoring SRF activity antagonizes Myc repression of SRF target genes, attenuates Myc-induced apoptosis, and reverts a Myc-dependent decrease in Akt phosphorylation and activity, a well-characterized suppressor of Myc-induced apoptosis. We propose that high levels of Myc engage Miz1 in repressive DNA binding complexes and suppress an SRF-dependent transcriptional program that supports survival of epithelial cells.

SNARE-dependent interaction of Src, EGFR and β1 integrin regulates invadopodia formation and tumor cell invasion

Acquisition of an invasive phenotype is prerequisite for tumor metastasis. Degradation of the extracellular matrix (ECM), and subsequent invasion by tumor cells, is mediated, in part, through subcellular structures called invadopodia. Src-dependent cytoskeletal rearrangements are required to form invadopodia, and here we identify an association between Src, epidermal growth factor receptor (EGFR), and β1 integrin that facilitates invadopodia formation. The association of Src, EGFR and β1 integrin is dependent upon membrane traffic that is mediated by syntaxin13 (officially known as STX12) and SNAP23; a similar dependence on these two SNARE proteins was observed for invadopodium-based matrix degradation and cell invasion. Inhibition of SNARE function impaired the delivery of Src and EGFR to developing invadopodia, as well as the β1-integrin-dependent activation of Src and phosphorylation of EGFR on Tyr residue 845. We also identified an association between SNAP23 and β1 integrin, and inhibition of β1 integrin increased this association, whereas the interaction between syntaxin13 and SNAP23 was reduced. The results suggest that SNARE-dependent trafficking is regulated, in part, by β1 integrin and is required for the delivery of Src and EGFR to sites of invadopodia formation in order to support tumor cell invasion.

Interfacial biology of in-stent restenosis

Percutaneous angioplasty is a nonsurgical method able to restore patency in atherosclerotic blood vessels through the expansion of a balloon. The clinical outcome of this technique has been significantly enhanced by the combined deployment of a stent. Although stents are successful in the majority of cases, a large percentage of patients (20-30%) still suffer a second vessel lumen reduction known as in-stent restenosis. In-stent restenosis is recognized to be caused by the mechanical and foreign body challenges elicited by the device. Drug-eluting stents have been recently made available to tackle restenosis, but their short clinical history and high costs may limit their future use. The present review links the most recent biologic findings related to in-stent restenosis to the devices' phyisico-chemical features in an attempt to demonstrate that a new generation of stents may be developed without the need of drug elution.

β1 integrin is a crucial regulator of pancreatic β-cell expansion

Development of the endocrine compartment of the pancreas, as represented by the islets of Langerhans, occurs through a series of highly regulated events encompassing branching of the pancreatic epithelium, delamination and differentiation of islet progenitors from ductal domains, followed by expansion and three-dimensional organization into islet clusters. Cellular interactions with the extracellular matrix (ECM) mediated by receptors of the integrin family are postulated to regulate key functions in these processes. Yet, specific events regulated by these receptors in the developing pancreas remain unknown. Here, we show that ablation of the β1 integrin gene in developing pancreatic β-cells reduces their ability to expand during embryonic life, during the first week of postnatal life, and thereafter. Mice lacking β1 integrin in insulin-producing cells exhibit a dramatic reduction of the number of β-cells to only ∼18% of wild-type levels. Despite the significant reduction in β-cell mass, these mutant mice are not diabetic. A thorough phenotypic analysis of β-cells lacking β1 integrin revealed a normal expression repertoire of β-cell markers, normal architectural organization within islet clusters, and a normal ultrastructure. Global gene expression analysis revealed that ablation of this ECM receptor in β-cells inhibits the expression of genes regulating cell cycle progression. Collectively, our results demonstrate that β1 integrin receptors function as crucial positive regulators of β-cell expansion.

Age-related alterations in T-lymphocytes modulate key pathways in prostate tumorigenesis

BACKGROUND

The primary risk for prostate cancer is aging, often associated with inflammation. Evidence implicates progressive age-related immune dysfunction with increased prostate cancer incidence and mortality. The aged T-cell response is characterized by increased production of pro-inflammatory cytokines, which could significantly contribute to prostate tumorigenesis through induction of key inflammation-mediated pro-survival factors.

METHODS

T-cell function of the young (<6 month-old) glycerol-3-phosphate acyltransferase-1 (GPAT-1) knock-out mouse mimics many of the hallmarks observed in an aged (>22-month-old) mouse. Serum and splenic T-lymphocytes from young GPAT-1(-/-) (6 months) and aged wild type (22 months) mice were collected for in vitro studies, including a cytokine immunoarray for serum cytokine levels, luciferase assays for NF-κB activation and Western blot analyses for protein expression.

RESULTS

The T-cell cytokine profile of the GPAT-1(-/-) mice mirrored that observed in aged wild type mice, including higher expression levels of IL-17. Serum- and T-cell-derived factors induced NF-κB activity in normal, non-transformed and prostate cancer epithelial cells, correlating with re-localization of NF-κB and increased protein expression of downstream targets of NF-κB.

CONCLUSION

The aging and aging-mimic mice produced circulating factors that induce pro-inflammatory pathways in prostate cells, most notably NF-κB. These findings provide evidence that an aged T-cell may directly contribute to the increased risk for prostate cancer in the elderly and establish that the GPAT-1(-/-) model, which mimics many of the characteristics of an aged immune system, is a viable tool for investigating this novel area of cancer risk.

Direct and indirect photodynamic therapy effects on the cellular and molecular components of the tumor microenvironment

Photodynamic therapy (PDT) is a novel cancer treatment. It involves the activation of a photosensitizer (PS) with light of specific wavelength, which interacts with molecular oxygen to generate singlet oxygen and other reactive oxygen species (ROS) that lead to tumor cell death. When a tumor is treated with PDT, in addition to affect cancer cells, the extracellular matrix and the other cellular components of the microenvironment are altered and finally this had effects on the tumor cells survival. Furthermore, the heterogeneity in the availability of nutrients and oxygen in the different regions of a tridimensional tumor has a strong impact on the sensitivity of cells to PDT. In this review, we summarize how PDT affects indirectly to the tumor cells, by the alterations on the extracellular matrix, the cell adhesion and the effects over the immune response. Also, we describe direct PDT effects on cancer cells, considering the intratumoral role that autophagy mediated by hypoxia-inducible factor 1 (HIF-1) has on the efficiency of the treatment.

Phosphatidylinositol-3 kinase activity in B cells is negatively regulated by Lyn tyrosine kinase

Phosphatidylinositol-3 kinase (PI3K) activity is essential for normal B-cell receptor (BCR)-mediated responses. To understand the mechanisms of PI3K regulation during B-cell activation, we performed a series of biochemical analysis on primary B cells, and found that activity of Src family tyrosine kinases (SFK) is crucial for the activation of PI3K following BCR ligation and this is regulated by the SFK Lyn. We show that the hyperresponsive phenotype of B cells lacking Lyn is predicated on significantly increased basal and inducible PI3K activity that correlates with the constitutive hypophosphorylation of PAG/Cbp (phosphoprotein associated with glycosphingolipid-enriched microdomains/Csk-binding protein), a concomitant reduction in bound Csk in Lyn(-/-) B cells and elevated levels of active Fyn. Regulating SFK activity may thus be a central mechanism by which Lyn regulates PI3K activity in B cells. This study defines the molecular connection between the BCR and PI3K and reveals this to be a point of Lyn-mediated regulation.

Integrin β1 mediates vaccinia virus entry through activation of PI3K/Akt signaling

Vaccinia virus has a broad range of infectivity in many cell lines and animals. Although it is known that the vaccinia mature virus binds to cell surface glycosaminoglycans and extracellular matrix proteins, whether additional cellular receptors are required for virus entry remains unclear. Our previous studies showed that the vaccinia mature virus enters through lipid rafts, suggesting the involvement of raft-associated cellular proteins. Here we demonstrate that one lipid raft-associated protein, integrin β1, is important for vaccinia mature virus entry into HeLa cells. Vaccinia virus associates with integrin β1 in lipid rafts on the cell surface, and the knockdown of integrin β1 in HeLa cells reduces vaccinia mature virus entry. Additionally, vaccinia mature virus infection is reduced in a mouse cell line, GD25, that is deficient in integrin β1 expression. Vaccinia mature virus infection triggers the activation of phosphatidylinositol 3-kinase (PI3K)/Akt signaling, and the treatment of cells with inhibitors to block P13K activation reduces virus entry in an integrin β1-dependent manner, suggesting that integrin β1-mediates PI3K/Akt activation induced by vaccinia virus and that this signaling pathway is essential for virus endocytosis. The inhibition of integrin β1-mediated cell adhesion results in a reduction of vaccinia virus entry and the disruption of focal adhesion and PI3K/Akt activation. In summary, our results show that the binding of vaccinia mature virus to cells mimics the outside-in activation process of integrin functions to facilitate vaccinia virus entry into HeLa cells.

Differential effects on cell motility, embryonic stem cell self-renewal and senescence by diverse Src kinase family inhibitors

The Src family of non-receptor tyrosine kinases (SFKs) has been shown to play an intricate role in embryonic stem (ES) cell maintenance. In the present study we have focused on the underlying molecular mechanisms responsible for the vastly different effects induced by various commonly used SFK inhibitors. We show that several diverse cell types, including fibroblasts completely lacking SFKs, cannot undergo mitosis in response to SU6656 and that this is caused by an unselective inhibition of Aurora kinases. In contrast, PP2 and PD173952 block motility immediately upon exposure and forces cells to grow in dense colonies. The subsequent halt in proliferation of fibroblast and epithelial cells in the center of the colonies approximately 24 h post-treatment appears to be caused by cell-to-cell contact inhibition rather than a direct effect of SFK kinase inhibition. Interestingly, in addition to generating more homogenous and dense ES cell cultures, without any diverse effect on proliferation, PP2 and PD173652 also promote ES cell self-renewal by reducing the small amount of spontaneous differentiation typically observed under standard ES cell culture conditions. These effects could not be mirrored by the use of Gleevec, a potent inhibitor of c-Abl and PDGFR kinases that are also inhibited by PP2.

β-Catenin mediates cyclic strain-stimulated cardiomyogenesis in mouse embryonic stem cells through ROS-dependent and integrin-mediated PI3K/Akt pathways

Wnt/β-catenin signaling regulates various cellular events involved in the proliferation and differentiation and these events are affected sensitively by applying to mechanical stimuli. However, the mechanisms by which mechanical force stimulates cardiomyogenesis are not extensively explored. In this study we investigated the cellular mechanisms by which β-catenin signaling regulates cardiac differentiation of strain-subjected embryonic stem (ES) cells. The application of cells to cyclic strain increased beating cardiomyocyte foci with the attendant increases of Cx 43 and Nkx 2.5 proteins. Anti-oxidants such as vitamin C or N-acetyl cysteine (NAC) blocked the strain-mediated increases of Cx 43, Nkx 2.5, and α5/β1 integrins. These anti-oxidants also suppressed the activation of phosphoinositide 3-kinase (PI3K) and Akt in cyclic strain-subjected cells. Western blot analysis revealed that PI3K is a critical downstream effector of β1 integrin signaling and mediates Cx 43 and Nkx 2.5 expression in cyclic strain-applied ES cells. Cyclic strain increased the expression of β-catenin and stimulated its nuclear translocation from the cytosol, which was prevented by anti-oxidant treatment. In addition, the application to cyclic strain increased mRNA expression of β-catenin target genes, Axin2 and c-myc, as well as the phosphorylation of glycogen synthase kinase-3β. Furthermore, the blockage of β-catenin by its specific siRNA transfection diminished the cellular levels of Cx 43 and Nkx 2.5 proteins and the number of beating cardiomyocyte foci. Collectively, these results suggest that β-catenin-mediated signaling is required for cyclic strain-stimulated cardiomyogenesis through ROS-dependent and integrin-mediated PI3K-Akt signaling cascades.

The critical protein interactions and structures that elicit growth deregulation in cancer and viral replication

One of the greatest challenges in biomedicine is to define the critical targets and network interactions that are subverted to elicit growth deregulation in human cells. Understanding and developing rational treatments for cancer requires a definition of the key molecular targets and how they interact to elicit the complex growth deregulation phenotype. Viral proteins provide discerning and powerful probes to understand both how cells work and how they can be manipulated using a minimal number of components. The small DNA viruses have evolved to target inherent weaknesses in cellular protein interaction networks to hijack the cellular DNA and protein replication machinery. In the battle to escape the inevitability of senescence and programmed cell death, cancers have converged on similar mechanisms, through the acquisition and selection of somatic mutations that drive unchecked cellular replication in tumors. Understanding the dynamic mechanisms through which a minimal number of viral proteins promote host cells to undergo unscheduled and pathological replication is a powerful strategy to identify critical targets that are also disrupted in cancer. Viruses can therefore be used as tools to probe the system-wide protein-protein interactions and structures that drive growth deregulation in human cells. Ultimately this can provide a path for developing system context-dependent therapeutics. This review will describe ongoing experimental approaches using viruses to study pathways deregulated in cancer, with a particular focus on viral cellular protein-protein interactions and structures.