Expression/activation of α5β1 integrin is linked to the β-catenin signaling pathway to drive migration in glioma cells

Glioma Cells Secrete Collagen VI to Facilitate Invasion

While glioblastoma (GBM) progression is associated with extensive extracellular matrix (ECM) secretion, the causal contributions of ECM secretion to invasion remain unclear. Here we investigate these contributions by combining engineered materials, proteomics, analysis of patient data, and a model of bevacizumab-resistant GBM. We find that GBM cells cultured in engineered 3D hyaluronic acid hydrogels secrete ECM prior to invasion, particularly in the absence of exogenous ECM ligands. Proteomic measurements reveal extensive secretion of collagen VI, and collagen VI-associated transcripts are correspondingly enriched in microvascular proliferation regions of human GBMs. We further show that bevacizumab-resistant GBM cells deposit more collagen VI than their responsive counterparts, which is associated with marked cell-ECM stiffening. COL6A3 deletion in GBM cells reduces invasion, β-catenin signaling, and expression of mesenchymal markers, and these effects are amplified in hypoxia. Our studies strongly implicate GBM cell-derived collagen VI in microenvironmental remodeling to facilitate invasion.

The Interplay between Integrins and Immune Cells as a Regulator in Cancer Immunology

Integrins are a group of heterodimers consisting of α and β subunits that mediate a variety of physiological activities of immune cells, including cell migration, adhesion, proliferation, survival, and immunotolerance. Multiple types of integrins act differently on the same immune cells, while the same integrin may exert various effects on different immune cells. In the development of cancer, integrins are involved in the regulation of cancer cell proliferation, invasion, migration, and angiogenesis; conversely, integrins promote immune cell aggregation to mediate the elimination of tumors. The important roles of integrins in cancer progression have provided valuable clues for the diagnosis and targeted treatment of cancer. Furthermore, many integrin inhibitors have been investigated in clinical trials to explore effective regimens and reduce side effects. Due to the complexity of the mechanism of integrin-mediated cancer progression, challenges remain in the research and development of cancer immunotherapies (CITs). This review enumerates the effects of integrins on four types of immune cells and the potential mechanisms involved in the progression of cancer, which will provide ideas for more optimal CIT in the future.

Targeting integrin pathways: mechanisms and advances in therapy

Integrins are considered the main cell-adhesion transmembrane receptors that play multifaceted roles as extracellular matrix (ECM)-cytoskeletal linkers and transducers in biochemical and mechanical signals between cells and their environment in a wide range of states in health and diseases. Integrin functions are dependable on a delicate balance between active and inactive status via multiple mechanisms, including protein-protein interactions, conformational changes, and trafficking. Due to their exposure on the cell surface and sensitivity to the molecular blockade, integrins have been investigated as pharmacological targets for nearly 40 years, but given the complexity of integrins and sometimes opposite characteristics, targeting integrin therapeutics has been a challenge. To date, only seven drugs targeting integrins have been successfully marketed, including abciximab, eptifibatide, tirofiban, natalizumab, vedolizumab, lifitegrast, and carotegrast. Currently, there are approximately 90 kinds of integrin-based therapeutic drugs or imaging agents in clinical studies, including small molecules, antibodies, synthetic mimic peptides, antibody-drug conjugates (ADCs), chimeric antigen receptor (CAR) T-cell therapy, imaging agents, etc. A serious lesson from past integrin drug discovery and research efforts is that successes rely on both a deep understanding of integrin-regulatory mechanisms and unmet clinical needs. Herein, we provide a systematic and complete review of all integrin family members and integrin-mediated downstream signal transduction to highlight ongoing efforts to develop new therapies/diagnoses from bench to clinic. In addition, we further discuss the trend of drug development, how to improve the success rate of clinical trials targeting integrin therapies, and the key points for clinical research, basic research, and translational research.

ITGB5 promotes innate radiation resistance in pancreatic adenocarcinoma by promoting DNA damage repair and the MEK/ERK signaling pathway

Pancreatic adenocarcinoma (PAAD) is one of the most aggressive digestive system tumors in the world, with a low early diagnosis rate and a high mortality. Integrin beta 5 (ITGB5) is demonstrated to be a potent tumor promoter in several carcinomas. However, it is unknown whether ITGB5 participates in the occurrence and development of PAAD. In this study, we confirmed a high expression of ITGB5 in PAAD and its role in promoting invasiveness and transitivity in PAAD. Besides, the knockdown of ITGB5 increased cell sensitivity to radiation by promoting DNA damage repair and the MEK/ERK signaling pathway. Collectively, these results show that ITGB5 plays an essential role in pancreatic cancer growth and survival.

Pituitary Apoplexy: Risk Factors and Underlying Molecular Mechanisms

Pituitary apoplexy is a rare syndrome, graded from asymptomatic subclinical apoplexy to a life-threatening condition due to pituitary ischemia or haemorrhage of an enlarged pituitary gland. The risk factors and the molecular underlying mechanisms are yet to be elucidated. We provide an overview of the general concepts, the potential factors associated with pituitary adenoma susceptibility for apoplectic events and the molecular mechanisms that could be involved such as HIF-1α/VEGF pathways and metalloproteinases activation, among others. The knowledge of the molecular mechanisms that could participate in the pathogenesis of pituitary apoplexy is crucial to advancement in the identification of future diagnostic tools and therapeutic targets in this rare but sometimes fatal condition.

Tissue transglutaminase activates integrin-linked kinase and β-catenin in ovarian cancer

Ovarian cancer (OC) is the most lethal gynecological cancer. OC cells have high proliferative capacity, are invasive, resist apoptosis, and tumors often display rearrangement of extracellular matrix (ECM) components, contributing to accelerated tumor progression. The multifunctional protein tissue transglutaminase (TG2) is known to be secreted in the tumor microenvironment (TME), where it interacts with fibronectin (FN) and the cell surface receptor β1 integrin. However, the mechanistic role of TG2 in cancer cell proliferation is unknown. Here, we demonstrate TG2 directly interacts with and facilitates the phosphorylation and activation of the integrin effector protein integrin-linked kinase (ILK) at Ser246. We show TG2 and p-Ser246-ILK form a complex that is detectable in patient-derived OC primary cells grown on FN-coated slides. In addition, we show co-expression of TGM2 and ILK correlates with poor clinical outcome. Mechanistically, we demonstrate TG2-mediated ILK activation causes phosphorylation of glycogen synthase kinase-3α/β (GSK-3α/β), allowing β-catenin nuclear translocation and transcriptional activity. Furthermore, inhibition of TG2 and ILK using small molecules, neutralizing antibodies, or shRNA-mediated knockdown block cell adhesion to the FN matrix, as well as the Wnt receptor response to the Wnt-3A ligand, and ultimately, cell adhesion, growth, and migration. In conclusion, we demonstrate TG2 directly interacts with and activates ILK in OC cells and tumors, and define a new mechanism which links ECM cues with β-catenin signaling in OC. These results suggest a central role of TG2/FN/integrin clusters in ECM rearrangement and indicate downstream effector ILK may represent a potential new therapeutic target in OC.

The CBP/β-Catenin Antagonist, ICG-001, Inhibits Tumor Metastasis via Blocking of the miR-134/ITGB1 Axis-Mediated Cell Adhesion in Nasopharyngeal Carcinoma

Simple Summary

Metastatic nasopharyngeal carcinoma (NPC) is incurable and remains the main cause of NPC death. Our previous studies found that the CBP/β-catenin Wnt antagonist, IGC-001, could inhibit the primary tumor formation of NPC tumor cells. Here, we further explored the anti-metastatic activity of ICG-001. We started by screening a panel of microRNAs that are related to epithelial–mesenchymal transition and cancer stem cell phenotypes; both properties can contribute to tumor metastasis. MicroRNA-134 was found to be consistently upregulated by ICG-001. The role of miR-134 in NPC is largely unknown but some studies found an association between low expression of miR-134 and poor prognosis. We examined the role of miR-134 in NPC with both in vitro and in vivo models and found that miR-134 could inhibit cancer cell adhesion, migration, and invasion. Our study provided a functional explanation for the poor prognosis observed in NPC patients with low or loss of miR-134 expression in their tumors and showed that modulation of the Wnt signaling by ICG-001 could effectively inhibit NPC metastasis via the miR-134/ITGB1 axis.

Abstract

Nasopharyngeal carcinoma (NPC) is an Epstein–Barr virus (EBV)-associated malignancy ranking as the 23rd most common cancer globally, while its incidence rate ranked the 9th in southeast Asia. Tumor metastasis is the dominant cause for treatment failure in NPC and metastatic NPC is yet incurable. The Wnt/β-catenin signaling pathway plays an important role in many processes such as cell proliferation, differentiation, epithelial–mesenchymal transition (EMT), and self-renewal of stem cells and cancer stem cells (CSCs). Both the EMT process and CSCs are believed to play a critical role in cancer metastasis. We here investigated whether the specific CBP/β-catenin Wnt antagonist, IGC-001, affects the metastasis of NPC cells. We found that ICG-001 treatment could reduce the adhesion capability of NPC cells to extracellular matrix and to capillary endothelial cells and reduce the tumor cell migration and invasion, events which are closely associated with distant metastasis. Through a screening of EMT and CSC-related microRNAs, it was found that miR-134 was consistently upregulated by ICG-001 treatment in NPC cells. Very few reports have mentioned the functional role of miR-134 in NPC, except that the expression was found to be downregulated in NPC. Transient transfection of miR-134 into NPC cells reduced their cell adhesion, migration, and invasion capability, but did not affect the growth of CSC-enriched tumor spheres. Subsequently, we found that the ICG-001-induced miR-134 expression resulting in downregulation of integrin β1 (ITGB1). Such downregulation reduced cell adhesion and migration capability, as demonstrated by siRNA-mediated knockdown of ITGB1. Direct targeting of ITGB1 by miR-134 was confirmed by the 3′-UTR luciferase assay. Lastly, using an in vivo lung metastasis assay, we showed that ICG-001 transient overexpression of miR-134 or stable overexpression of miR-134 could significantly reduce the lung metastasis of NPC cells. Taken together, we present here evidence that modulation of Wnt/β-catenin signaling pathway could inhibit the metastasis of NPC through the miR-134/ITGB1 axis.

Enhancement of Farnesoid X Receptor Inhibits Migration, Adhesion and Angiogenesis through Proteasome Degradation and VEGF Reduction in Bladder Cancers

(1) Background: Bladder cancer is a malignant tumor mainly caused by exposure to environmental chemicals, with a high recurrence rate. NR1H4, also known as Farnesoid X Receptor (FXR), acts as a nuclear receptor that can be activated by binding with bile acids, and FXR is highly correlated with the progression of cancers. The aim of this study was to verify the role of FXR in bladder cancer cells. (2) Methods: A FXR overexpressed system was established to investigate the effect of cell viability, migration, adhesion, and angiogenesis in low-grade TSGH8301 and high-grade T24 cells. (3) Results: After FXR overexpression, the ability of migration, adhesion, invasion and angiogenesis of bladder cancer cells declined significantly. Focal adhesive complex, MMP2, MMP9, and angiogenic-related proteins were decreased, while FXR was overexpressed in bladder cancer cells. Moreover, FXR overexpression reduced vascular endothelial growth factor mRNA and protein expression and secretion in bladder cancer cells. After treatment with the proteosome inhibitor MG132, the migration, adhesion and angiogenesis caused by FXR overexpression were all reversed in bladder cancer cells. (4) Conclusions: These results may provide evidence on the role of FXR in bladder cancer, and thus may improve the therapeutic efficacy of urothelial carcinoma in the future.

Temozolomide-Acquired Resistance Is Associated with Modulation of the Integrin Repertoire in Glioblastoma, Impact of α5β1 Integrin

Despite extensive treatment, glioblastoma inevitably recurs, leading to an overall survival of around 16 months. Understanding why and how tumours resist to radio/chemotherapies is crucial to overcome this unmet oncological challenge. Primary and acquired resistance to Temozolomide (TMZ), the standard-of-care chemotherapeutic drug, have been the subjects of several studies. This work aimed to evaluate molecular and phenotypic changes occurring during and after TMZ treatment in a glioblastoma cell model, the U87MG. These initially TMZ-sensitive cells acquire long-lasting resistance even after removal of the drug. Transcriptomic analysis revealed that profound changes occurred between parental and resistant cells, particularly at the level of the integrin repertoire. Focusing on α5β1 integrin, which we proposed earlier as a glioblastoma therapeutic target, we demonstrated that its expression was decreased in the presence of TMZ but restored after removal of the drug. In this glioblastoma model of recurrence, α5β1 integrin plays an important role in the proliferation and migration of tumoral cells. We also demonstrated that reactivating p53 by MDM2 inhibitors concomitantly with the inhibition of this integrin in recurrent cells may overcome the TMZ resistance. Our results may explain some integrin-based targeted therapy failure as integrin expressions are highly switchable during the time of treatment. We also propose an alternative way to alter the viability of recurrent glioblastoma cells expressing a high level of α5β1 integrin.

Wnt10a/β-catenin signalling is involved in kindlin-1-mediated astrocyte activation in a chronic construction injury rat model

The activation of spinal astrocytes and release of neuroinflammatory mediators are important events in neuropathic pain (NP) pathogenesis. In this study, we investigated the role of Wnt10a/β-catenin signalling in kindlin-1-mediated astrocyte activation using a chronic constriction injury (CCI) NP rat model. Using kindlin-1 overexpression and knockdown plasmids, we assessed hyperalgesia, changes in spinal astrocyte activation and the release of inflammatory mediators in a NP rat model. We also performed coimmunoprecipitation, Western blotting and real-time polymerase chain reaction (PCR) to characterize the underlying mechanisms of kindlin-1 in astrocyte cultures in vitro. Kindlin-1 was significantly upregulated in CCI rats and promoted hyperalgesia. Moreover, we observed increased kindlin-1, Wnt10a and glial fibrillary acidic protein (GFAP; biomarker for astroglial injury) levels and the release of inflammatory mediators in NP rats (p < 0.05). Inhibiting GFAP in vitro led to decreased kindlin-1 levels, prevented astrocyte activation, decreased Wnt10a level and the release of inflammatory mediators (p < 0.05). Coimmunoprecipitation showed that kindlin-1 can interact with Wnt10a. We showed that kindlin-1-mediated astrocyte activation was associated with Wnt10a/β-catenin signalling and the downstream release of inflammatory mediators in a CCI NP rat model. Our findings provide novel insights into the molecular mechanisms of kindlin-1-mediated astrocyte activation after CCI.

Adipose-PAS interactions in the context of its localised bio-engineering potential (Review)

Adipocytes are a known source of stem cells. They are easy to harvest, and are a suitable candidate for autogenous grafts. Adipose derived stem cells (ADSCs) have multiple target tissues which they can differentiate into, including bone and cartilage. In adipose tissue, ADSCs are able to differentiate, as well as providing energy and a supply of cytokines/hormones to manage the hypoxic and lipid/hormone saturated adipose environment. The plasminogen activation system (PAS) controls the majority of proteolytic activities in both adipose and wound healing environments, allowing for rapid cellular migration and tissue remodelling. While the primary activation pathway for PAS occurs through the urokinase plasminogen activator (uPA), which is highly expressed by endothelial cells, its function is not limited to enabling revascularisation. Proteolytic activity is dependent on protease activation, localisation, recycling mechanisms and substrate availability. uPA and uPA activated plasminogen allows pluripotent cells to arrive to new local environments and fulfil the niche demands. However, overstimulation, the acquisition of a migratory phenotype and constant protein turnover can be unconducive to the formation of structured hard and soft tissues. To maintain a suitable healing pattern, the proteolytic activity stimulated by uPA is modulated by plasminogen activator inhibitor 1. Depending on the physiological settings, different parts of the remodelling mechanism are activated with varying results. Utilising the differences within each microenvironment to recreate a desired niche is a valid therapeutic bio-engineering approach. By controlling the rate of protein turnover combined with a receptive stem cell lineage, such as ADSC, a novel avenue on the therapeutic opportunities may be identified, which can overcome limitations, such as scarcity of stem cells, low angiogenic potential or poor host tissue adaptation.

The Roles of Integrin α5β1 in Human Cancer

Cell adhesion to the extracellular matrix has important roles in tissue integrity and human health. Integrins are heterodimeric cell surface receptors that are composed by two non-covalently linked alpha and beta subunits that mainly participate in the interaction of cell-cell adhesion and cell-extracellular matrix and regulate cell motility, adhesion, differentiation, migration, proliferation, etc. In mammals, there have been eighteen α subunits and 8 β subunits and so far 24 distinct types of αβ integrin heterodimers have been identified in humans. Integrin α5β1, also known as the fibronectin receptor, is a heterodimer with α5 and β1 subunits and has emerged as an essential mediator in many human carcinomas. Integrin α5β1 alteration is closely linked to the progression of several types of human cancers, including cell proliferation, angiogenesis, tumor metastasis, and cancerogenesis. In this review, we will introduce the functions of integrin α5β1 in cancer progression and also explore its regulatory mechanisms. Additionally, the potential clinical applications as a target for cancer imaging and therapy are discussed. Collectively, the information reviewed here may increase the understanding of integrin α5β1 as a potential therapeutic target for cancer.

Rapha Myr®, a Blend of Sulforaphane and Myrosinase, Exerts Antitumor and Anoikis-Sensitizing Effects on Human Astrocytoma Cells Modulating Sirtuins and DNA Methylation

Brain and other nervous system cancers are the 10th leading cause of death worldwide. Genome instability, cell cycle deregulation, epigenetic mechanisms, cytoarchitecture disassembly, redox homeostasis as well as apoptosis are involved in carcinogenesis. A diet rich in fruits and vegetables is inversely related with the risk of developing cancer. Several studies report that cruciferous vegetables exhibited antiproliferative effects due to the multi-pharmacological functions of their secondary metabolites such as isothiocyanate sulforaphane deriving from the enzymatic hydrolysis of glucosinolates. We treated human astrocytoma 1321N1 cells for 24 h with different concentrations (0.5, 1.25 and 2.5% v/v) of sulforaphane plus active myrosinase (Rapha Myr®) aqueous extract (10 mg/mL). Cell viability, DNA fragmentation, PARP-1 and γH2AX expression were examined to evaluate genotoxic effects of the treatment. Cell cycle progression, p53 and p21 expression, apoptosis, cytoskeleton morphology and cell migration were also investigated. In addition, global DNA methylation, DNMT1 mRNA levels and nuclear/mitochondrial sirtuins were studied as epigenetic biomarkers. Rapha Myr® exhibited low antioxidant capability and exerted antiproliferative and genotoxic effects on 1321N1 cells by blocking the cell cycle, disarranging cytoskeleton structure and focal adhesions, decreasing the integrin α5 expression, renewing anoikis and modulating some important epigenetic pathways independently of the cellular p53 status. In addition, Rapha Myr® suppresses the expression of the oncogenic p53 mutant protein. These findings promote Rapha Myr® as a promising chemotherapeutic agent for integrated cancer therapy of human astrocytoma.

Combating Glioblastoma by Codelivering the Small-Molecule Inhibitor of STAT3 and STAT3siRNA with α5β1 Integrin Receptor-Selective Liposomes

Glioblastoma multiforme (GBM) is one of the most aggressive tumors with a median survival of only 15 months. Effective therapeutics need to overcome the formidable challenge of crossing the blood-brain barrier (BBB). Receptors and transporters overexpressed on BCECs are being used for designing liposomes, polymers, polymeric micelles, peptides, and dendrimer-based drug carriers for combating brain tumors. Herein, using the orthotopic mouse glioblastoma model, we show that codelivering a small-molecule inhibitor of the JAK/STAT pathway (WP1066) and STAT3siRNA with nanometric (100-150 nm) α5β1 integrin receptor-selective liposomes of RGDK-lipopeptide holds therapeutic promise in combating glioblastoma. Rh-PE (red)-labeled liposomes of RGDK-lipopeptide were found to be internalized in GL261 cells via integrin α5β1 receptors. Intravenously administered near-infrared (NIR)-dye-labeled α5β1 integrin receptor-selective liposomes of RGDK-lipopeptide were found to be accumulated preferentially in the mouse brain tumor tissue. Importantly, we show that iv injection of WP1066 (a commercially sold small-molecule inhibitor of the JAK/STAT pathway) and STAT3siRNA cosolubilized within the liposomes of RGDK-lipopeptide leads to significant inhibition (>350% compared to the untreated mice group) of orthotopically growing mouse glioblastoma. The present strategy may find future use in combating GBM.

Nanofiber Alignment Mediates the Pattern of Single Cell Migration

In natural tissue, nanofibrils in extracellular matrix (ECM), such as collagen fibrils, direct cell migration through contacting guidance. The contacting nanofibers on cell-ECM interface are reorganized from curl fibers to straightened fibers. However, how these nanofibers regulate single cell migration remains obscure. To investigate this issue, we fabricated collagen/polymer based biomimetic nanofiber sheets of varying topography. And we selected tumorigenic cell KGN and nontumorigenic cell 293T for comparison. We found KGN showed higher sensitivity to the nanofiber alignment rather than the nontumorigenic cell 293T, in morphological change, trajectory adaptation, and velocity variation. We also found aligned nanofibers shaped both KGN and 293T into elongated spindle morphology. Comparatively, KGN had greater perimeter and lower roundness than 293T. To study the dynamics of single cell migration of KGN and 293T, we conducted trajectory tracking and siRNA validation on regulatory proteins. We found nanofibers of varying topography regulated the patterns of single cell migration differently. For KGN cell, β-catenin, Rac1, and Cdc42 participated in its directional migration, but it was impervious to vimentin. Comparatively, epithelial cell 293T involved vimentin in its directional migration.

Extracellular nanofiber-orchestrated cytoskeletal reorganization and mediated directional migration of cancer cells

Extracellular matrix anisotropy tunes the organization and movement of surrounding cells. The primary mediators of the extracellular matrix are fiber-based materials. Natural collagen fibers reorganize from curled and isotropic fibers to straightened and anisotropic fibers during tumorigenesis, yet how the cytoskeleton is involved in the directional migration in response to the topography is unknown. To investigate this, we fabricated random, orthogonal, and aligned nanofibers to deconstruct the basic mechanisms for the migration of the human pancreatic cancer cells PANC-1 on different substrates. We found that the extracellular matrix orchestrated actin reorganization by templating the surface topography as an irregular pattern on random fibers, crossover feature on orthogonal fibers, and parallel characteristics on aligned fibers. The intermediate filament as vimentin was upregulated to form a perinuclear shape on orthogonal or aligned surfaces. We also found that the nanofiber topography mediated the directional migration via different mechanisms. The directionality ratio and velocity were statistically analyzed to unveil the pattern of directional migration. Cells on aligned nanofibers yielded a greater velocity. Rac1 and Cdc42 were involved in cell migration through regulating actin polymerization and membrane protrusions. Thus, our findings elucidate that nanofiber alignment orchestrates cytoskeletal reorganization and mediates the directional migration of cancer cells.

Integrin Signaling in Glioma Pathogenesis: From Biology to Therapy

Integrins are a large family of transmembrane adhesion receptors, which play a key role in interactions of a cell with the surrounding stroma. Integrins are comprised of non-covalently linked α and β chains, which form heterodimeric receptor complexes. The signals from integrin receptors are combined with those originating from growth factor receptors and participate in orchestrating morphological changes of cells, organization of the cytoskeleton, stimulation of cell proliferation and rescuing cells from programmed cell death induced by extracellular matrix (ECM) detachment. Upon binding to specific ligands or ECM components, integrin dimers activate downstream signaling pathways, including focal adhesion kinase, phosphoinositide-3-kinase (PI3K) and AKT kinases, which regulate migration, invasion, proliferation and survival. Expression of specific integrins is upregulated in both tumor cells and stromal cells in a tumor microenvironment. Therefore, integrins became an attractive therapeutic target for many cancers, including the most common primary brain tumors-gliomas. In this review we provide an overview of the involvement of integrin signaling in glioma pathogenesis, formation of the tumor niche and brain tissue infiltration. We will summarize up-to-date therapeutic strategies for gliomas focused on interference with integrin ligand-receptor signaling.

The Extracellular Matrix Modulates the Metastatic Journey

The extracellular matrix is perturbed in tumors. The tumor matrix promotes the growth, survival, and invasion of the cancer and modifies fibroblast and immune cell behavior to drive metastasis and impair treatment. Here, we discuss how the tumor matrix regulates metastasis by fostering tumor cell invasion into the stroma and migration toward the vasculature. We describe the role of the tumor matrix in cancer cell intravasation and vascular dissemination. We examine the impact of the matrix on disseminated tumor cell extravasation and on tumor dormancy and metastatic outgrowth. Finally, we discuss the clinical outcome of therapeutics that normalize tumor-matrix interactions.

Polarization of Reactive Astrocytes in Response to Spinal Cord Injury is Enhanced by M2 Macrophage-Mediated Activation of Wnt/β-Catenin Pathway

Understanding the mechanisms of glial scar formation by reactive astrocytes is crucial for elaborating a therapeutic strategy to brain and spinal cord injury. However, the extrinsic mechanisms that drive the polarization of reactive astrocytes, the first step in glial scar formation, remain poorly understood. Here, using an in vitro chemotaxis assay as an experimental model for polarization, we observed that Il4-M2 macrophages are stronger inducers of reactive astrocytes' polarization, compared to naive or M1 macrophages. Then, we showed that both β1-integrin and Wnt/β-catenin pathways in astrocytes are required for this polarization in vitro and in vivo after spinal cord crush injury in mice. These findings provide molecular targets for manipulating the polarization of reactive astrocytes in order to potentially enhance the healing of SCI lesions.

FRK suppresses human glioma growth by inhibiting ITGB1/FAK signaling

Fyn-related kinase (FRK), a member of the Src-related tyrosine kinase family, functions as a tumor suppressor in several malignancies. We previously showed that FRK overexpression inhibited the growth of glioma cells. However, it is unknown whether FRK is equally effective against intracranial glioma in vivo, and the mechanism by which FRK influences glioma cell growth remains unclear. In this study, we found that tumor volume was reduced by about one-third in mice with FRK overexpression, which showed improved survival relative to controls. Immunofluorescence analysis revealed that FRK overexpression inhibited glioma cell proliferation and induced their apoptosis. Importantly, in vitro we further found that FRK decreased the expression of integrin subunit β1 (ITGB1) at both the mRNA and protein levels. FRK also inhibited transactivation by ITGB1, resulting in the suppression of its target proteins AKT and focal adhesion kinase (FAK). ITGB1 overexpression promoted glioma cell growth and partially reduced FRK-induced growth suppression. These results indicate that FRK inhibits human glioma growth via regulating ITGB1/FAK signaling and provide a potential therapeutic target for the treatment of glioma.

Molecular and Clinical Insights into the Invasive Capacity of Glioblastoma Cells

The invasive capacity of GBM is one of the key tumoral features associated with treatment resistance, recurrence, and poor overall survival. The molecular machinery underlying GBM invasiveness comprises an intricate network of signaling pathways and interactions with the extracellular matrix and host cells. Among them, PI3k/Akt, Wnt, Hedgehog, and NFkB play a crucial role in the cellular processes related to invasion. A better understanding of these pathways could potentially help in developing new therapeutic approaches with better outcomes. Nevertheless, despite significant advances made over the last decade on these molecular and cellular mechanisms, they have not been translated into the clinical practice. Moreover, targeting the infiltrative tumor and its significance regarding outcome is still a major clinical challenge. For instance, the pre- and intraoperative methods used to identify the infiltrative tumor are limited when trying to accurately define the tumor boundaries and the burden of tumor cells in the infiltrated parenchyma. Besides, the impact of treating the infiltrative tumor remains unclear. Here we aim to highlight the molecular and clinical hallmarks of invasion in GBM.

YB-1 modulates the drug resistance of glioma cells by activation of MDM2/p53 pathway

Background

Y-box-binding protein-1 (YB-1) is aberrantly expressed in a variety of cancers. However, the biological functional role of YB-1 in glioma is not yet clear.

Methods

The expression of MDM2 and YB-1 was analyzed by real time PCR. Overexpression and knockdown of YB-1 in glioma cells were created by transfection of pcDNA-YB-1 and siRNA against YB-1, respectively. Cell viability was performed by CCK8 assay.

Results

Our findings showed that glioma tissues had higher expressions of YB-1 than that in cancer-free tissues in 54 glioma patients, which were also positively correlated with Murine MDM2 expression. Overexpression of YB-1 or MDM2 renders a drug resistance feature in glioma cell exposed to temozolomide (TMZ), by directly targeting p53. Genetic or chemical inhibition of MDM2 significantly blocked YB-1-modulated response of glioma cells to TMZ. Moreover, inhibition of YB-1 or MDM2 reduced glioma cells metastasis and mortality in mice.

Conclusion

YB-1 facilitates the resistance of glioma cells to TMZ by direct activation of MDM2/p53 signaling and represents a promising molecular target for glioma treatment.

Elevated expression of Twinfilin-1 is correlated with inferior prognosis of lung adenocarcinoma

AIM

Twinfilin-1 (TWF1) has been implicated in cell motility, invasion and migration. However, its exact role in lung cancer progression is still unclear. In the present study, we explored clinical and prognostic relevance of Twinfilin-1 (TWF1) levels for non-small cell lung carcinoma (NSCLC).

MAIN METHODS

The Cancer Genome Atlas (TCGA) dataset was analyzed for possible association between TWF1 expressions in NSCLC tissues and patient prognosis. The meta-analysis data was validated in our clinical study through techniques of immunoblotting, expression analysis and immunohistochemistry.

KEY FINDINGS

Lung adenocarcinoma (LUAD) as well as lung squamous cell carcinoma (LUSC) showed significantly elevated expression of TWF1 compared to normal lung tissues. Univariate Cox regression analysis showed high expression of TWF1 to be independent prognostic indicator involved in overall survival (hazard ratio: 1.636; 95% CI: 1.223-2.189) and recurrence-free survival (hazard ratio: 1.551; 95% CI: 1.158-2.077) in LUAD, but not in LUSC. Similar trend was found in our clinical study. LUAD tissues reflected TWF1 overexpression to be positively correlated with grade of tumor, size and lymph node metastasis. Enhanced TWF1 expression was identified to be an independent predictor for the disadvantageous prognosis of LUAD through simultaneously both univariate as well as multivariate Cox regression analyses (both p < 0.05). Kaplan-Meier survival graphs further corroborated that poor disease prediction in the patients with LUAD was indicated through high TWF1 expression (p = 0.028).

SIGNIFICANCE

Robustness and poor prognosis in LUAD correlated with TWF1 levels thus making it a suitable therapeutic target against LUAD.

Simultaneous Targeting of RGD-Integrins and Dual Murine Double Minute Proteins in Glioblastoma Multiforme

In the fight against Glioblastoma Multiforme, recent literature data have highlighted that integrin α5β1 and p53 are part of convergent pathways in the control of glioma apoptosis. This observation prompted us to seek a molecule able to simultaneously modulate both target families. Analyzing the results of a previous virtual screening against murine double minute 2 protein (MDM2), we envisaged that Arg-Gly-Asp (RGD)-mimetic molecules could be inhibitors of MDM2/4. Herein, we present the discovery of compound 7, which inhibits both MDM2/4 and α5β1/αvβ3 integrins. A lead optimization campaign was carried out on 7 with the aim to preserve the activities on integrins while improving those on MDM proteins. Compound 9 turned out to be a potent MDM2/4 and α5β1/αvβ3 blocker. In p53-wild type glioma cells, 9 arrested cell cycle and proliferation and strongly reduced cell invasiveness, emerging as the first molecule of a novel class of integrin/MDM inhibitors, which might be especially useful in subpopulations of patients with glioblastoma expressing a functional p53 concomitantly with a high level of α5β1 integrin.

PHAP1 promotes glioma cell proliferation by regulating the Akt/p27/stathmin pathway

PHAP1 (Putative HLA‐DR‐associated protein 1), also termed acidic leucine‐rich nuclear phosphoprotein 32A (ANP32A), Phosphoprotein 32 (pp32) or protein phosphatase 2A inhibitor (I1PP2A), is a multifunctional protein aberrantly expressed in multiple types of human cancers. However, its expression pattern and clinical relevance in human glioma remain unknown. In this study, Western blotting and immunohistochemistry analysis demonstrated PHAP1 protein was highly expressed in glioma patients, especially in those with high‐grade disease. Publicly available data also revealed high levels of PHAP1 were associated with poor prognosis in glioma patients. The functional studies showed that knock‐down of PHAP1 suppressed the proliferation of glioma cells, while overexpression of PHAP1 facilitated it. The iTRAQ proteomic analysis suggested that stathmin might be a potential downstream target of PHAP1. Consistently, PHAP1 knock‐down significantly decreased the expression of stathmin, while overexpression of PHAP1 increased it. Also, the upstream negative regulator, p27, expression levels increased upon PHAP1 knock‐down and decreased when PHAP1 was overexpressed. As a result, the phosphorylated Akt (S473), an upstream regulator of p27, expression levels decreased upon silencing of PHAP1, but elevated after PHAP1 overexpression. Importantly, we demonstrate the p27 down‐regulation, stathmin up‐regulation and cell proliferation acceleration induced by PHAP1 overexpression were dependent on Akt activation. In conclusion, the above results suggest that PHAP1 expression is elevated in glioma patients, which may accelerate the proliferation of glioma cells by regulating the Akt/p27/stathmin pathway.

Role of Corneal Stromal Cells on Epithelial Cell Function during Wound Healing

Following injury, corneal stromal keratocytes transform into repair-phenotype of activated stromal fibroblasts (SFs) and participate in wound repair. Simultaneously, ongoing bi-directional communications between corneal stromal-epithelial cells also play a vital role in mediating the process of wound healing. Factors produced by stromal cells are known to induce proliferation, differentiation, and motility of corneal epithelial cells, which are also subsequently the main processes that occur during wound healing. In this context, the present study aims to investigate the effect of SFs conditioned medium (SFCM) on corneal epithelial cell function along with substance P (SP). Antibody microarrays were employed to profile differentially expressed cell surface markers and cytokines in the presence of SFCM and SP. Antibody microarray data revealed enhanced expression of the ITGB1 in corneal epithelial cells following stimulation with SP whereas SFCM induced abundant expression of IL-8, ITGB1, PD1L1, PECA1, IL-15, BDNF, ICAM1, CD8A, CD44 and NTF4. All these proteins have either direct or indirect roles in epithelial cell growth, movement and adhesion related signaling cascades during tissue regeneration. We also observed activation of MAPK signaling pathway along with increased expression of focal adhesion kinase (FAK), paxillin, vimentin, β-catenin and vasodilator-stimulated phosphoprotein (VASP) phosphorylation. Additionally, epithelial-to-mesenchymal transition (EMT) regulating transcription factors Slug and ZEB1 expression were enhanced in the presence of SFCM. SP enriched the expression of integrin subunits α4, α5, αV, β1 and β3 whereas SFCM increased α4, α5, αV, β1 and β5 integrin subunits. We also observed increased expression of Serpin E1 following SP and SFCM treatment. Wound healing scratch assay revealed enhanced migration of epithelial cells following the addition of SFCM. Taken together, we conclude that SFCM-mediated sustained activation of ZEB1, Slug in combination with upregulated migration-associated integrins and ERK (Extracellular signal-regulated kinase)-FAK-paxillin axis, may lead to induce type 2 EMT-like changes during corneal epithelial wound healing.

Octreotide-modified liposomes containing daunorubicin and dihydroartemisinin for treatment of invasive breast cancer

Tumor invasion is considered a major promoter in the initiation of tumor metastasis, which is supposed to cause most cancer-related deaths. In the present study, octreotide (OCT)-modified daunorubicin plus dihydroartemisinin liposomes were developed and characterized. Evaluations were undertaken on breast cancer MDA-MB-435S cells and MDA-MB-435S xenografts nude mice. The liposomes were ∼100 nm in size with a narrow polydispersity index. In vitro results showed that the OCT-modified daunorubicin plus dihydroartemisinin liposomes could enhance cytotoxicity and cellular uptake by OCT-SSTRs (somatostatin receptors)-mediated active targeting, block on tumor cell wound healing and migration by incorporating dihydroartemisinin. The action mechanism might be related to regulations on E-cadherin, α5β1-integrin, TGF-β1, VEGF and MMP2/9 in breast cancer cells. In vivo, the liposomes displayed a prolonged circulating time, more accumulation in tumor location, and a robust overall antitumor efficacy with no obvious toxicity at the test dose in MDA-MB-435S xenograft mice. In conclusion, the OCT-modified daunorubicin plus dihydroartemisinin liposomes could prevent breast cancer invasion, hence providing a possible strategy for treatment of metastatic breast cancer.

MicroRNA-19 contributes to the malignant phenotypes of osteosarcoma in vitro by targeting Pax6

This study was conducted to detect the expression of miR-19 and Pax6 (Paired box protein 6) in human osteosarcoma cells and the effects on biological characteristics of osteosarcoma cells. Quantitative real-time polymerase chain reaction was used to detect the expression of Pax6 and miR-19 in normal human osteoblasts (hFOB 1.19) and osteosarcoma cell lines (U2OS, Saos-2, and MG-63). Results showed that miR-19 was significantly upregulated in osteosarcoma cell lines compared with that in hFOB 1.19 cells, while the expression of Pax6 messenger RNA was significantly downregulated. Pax6 was defined as the target gene of miR-19 which was validated by luciferase reporter gene analysis. Results indicated that miR-19 had an interaction with Pax6 3'-untranslated region. At the same time, the protein expression of Pax6 was significantly decreased in the MG-63 cells transfected with miR-19 mimic and was notably enhanced in osteosarcoma MG-63 cells transfected with miR-19 inhibitor. These data suggested that Pax6 was a target of miR-19 in osteosarcoma MG-63 cells. The effects of miR-19 on the biological behavior of MG-63 cells were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, flow cytometry, and Transwell assay. Results showed that the downregulation of miR-19 inhibited cell viability, reduced the percentage of cells in S phase and the number of cells passing through the Transwell chamber, and increased the number of apoptotic cells. Western blot analysis showed that the inhibition of miR-19 significantly increased the expression of epithelial proteins (E-cadherin and β-catenin) and decreased the expression of mesenchymal protein (Vimentin), extracellular signal-regulated kinase, and phosphorylated extracellular signal-regulated kinase in MG-63 cells. MiR-19 inhibitor and Pax6 small interfering RNA were simultaneously transfected into MG-63 cells. Results from 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, flow cytometry, and Transwell assay demonstrated that the inhibition of Pax6 expression in MG-63 cells could reverse the cell biological effects induced by the inhibition of miR-19 expression. Based on these findings, it was suggested that miR-19, upregulated in osteosarcoma cells, negatively regulated the expression of Pax6, which can promote the malignant phenotypes of osteosarcoma cells via activation of the extracellular signal-regulated kinase signaling pathways. Therefore, miR-19/Pax6 may offer potential for use as a target for the treatment of osteosarcoma.

Integrin α5 triggers the metastatic potential in renal cell carcinoma

The therapy of advanced renal cell carcinoma (RCC) is still a major challenge. To intervene therapeutically a deeper comprehension of the particular steps of metastasis is necessary. In this context membrane bound receptors like integrins play a decisive role. We analyzed the integrin α5 expression in 141 clear cell RCC patients by Western blot. Patients with RCC expressed a significant higher level of integrin α5 in tumor than in normal tissue. The integrin α5 expression correlated with tumor grade, the development of distant metastases within five years after tumor nephrectomy and reduced survival. The RCC cell lines Caki-1 and CCF-RC1, which highly express integrin α5, were treated with fibronectin in combination with or without an inhibiting anti-integrin α5 antibody. Afterwards the migration, adhesion, viability and prominent signaling molecules were analyzed. Both cell lines showed a significant reduced migration potential as well as a decreased adhesion potential to fibronectin after treatment with an integrin α5 blocking antibody. A contribution of the AKT and ERK1/2 signaling pathways could be demonstrated. The results indicate integrin α5 as a potent marker to discriminate patients’ tumor prognosis. Consequently the integrin subunit α5 can be considered as a target for individual therapy of advanced RCC.

Interest of integrins targeting in glioblastoma according to tumor heterogeneity and cancer stem cell paradigm: an update

Glioblastomas are malignant brain tumors with dismal prognosis despite standard treatment with surgery and radio/chemotherapy. These tumors are defined by an important cellular heterogeneity and notably contain a particular subpopulation of Glioblastoma-initiating cells, which recapitulate the heterogeneity of the original Glioblastoma. In order to classify these heterogeneous tumors, genomic profiling has also been undertaken to classify these heterogeneous tumors into several subtypes. Current research focuses on developing therapies, which could take into account this cellular and genomic heterogeneity. Among these targets, integrins are the subject of numerous studies since these extracellular matrix transmembrane receptors notably controls tumor invasion and progression. Moreover, some of these integrins are considered as membrane markers for the Glioblastoma-initiating cells subpopulation. We reviewed here integrin expression according to glioblastoma molecular subtypes and cell heterogeneity. We discussed their roles in glioblastoma invasion, angiogenesis, therapeutic resistance, stemness and microenvironment modulations, and provide an overview of clinical trials investigating integrins in glioblastomas. This review highlights that specific integrins could be identified as selective glioblastoma cells markers and that their targeting represents new diagnostic and/or therapeutic strategies.

Diallyl trisulfide inhibits proliferation, invasion and angiogenesis of glioma cells by inactivating Wnt/β-catenin signaling

Aberrant activation of Wnt/β-catenin signaling leads to increased cell proliferation and survival and promotes the development of various human tumors, including glioma, one of the most common primary brain tumors. The treatment efficacy of many anticancer drugs remains limited or unsatisfactory and it is urgently necessary to develop effective and low-toxicity anticancer drugs or strategies, especially for glioma. Here, we report that diallyl trisulfide suppresses survival, migration, invasion and angiogenesis in glioma cells. These effects were associated with inhibition of the Wnt/β-catenin signaling cascade, which was accompanied by decreased expression of LRP6, TRIM29 and Pygo2. A dual-luciferase reporter assay confirmed that DATS treatment decreased TCF/LEF-mediated transcription. Finally, a nude mouse tumorigenicity model was used to examine the biological effect of diallyl trisulfide in vivo. Consistent with the previous results, diallyl trisulfide inhibited proliferation, invasion and angiogenesis in glioma cells by suppressing Wnt/β-catenin signaling.

NBPF7 promotes the proliferation of α-catenin-knockdown HaCaT cells via functional interaction with the NF-κB pathway

Loss of key components that form cell-cell adherens junctions, such as α-catenin, triggers severe epidermal hyperproliferation. However, the underlying molecular mechanisms remain largely unknown. We report here that neuroblastoma breakpoint family (NBPF) genes are upregulated and that NBPF7 specifically promotes cellular proliferation of α-catenin-silenced HaCaT cells through functional linkage with the NF-κB pathway. Genome-wide profiling of HaCaT cells shows that NBPF genes are upregulated following α-catenin knockdown. Data from western blot analyses are consistent with the activation of the NF-κB pathway as well as increased expression of NBPF7 by α-catenin knockdown. Co-immunoprecipitation assays indicate that NBPF7 could be detected in endogenous activated NF-κB immunoprecipitates. Immunoflurence analyses demonstrate that NBPF7 co-localizes with activated NF-κB in the nucleus after α-catenin silencing. Moreover, inhibition of NBPF7 decreases the proliferation of HaCaT cells and abolishes the enhanced proliferation associated with α-catenin knockdown in HaCaT cells. These results indicate that NBPF7 plays a key role in the α-catenin signaling pathway that regulates cell proliferation of keratinocytes. Our findings suggest that the classical NF-κB pathway plays a critical role in cellular proliferation and that NBPF7 is a functional mediator for α-catenin in the regulation of keratinocyte growth.

CBX7 negatively regulates migration and invasion in glioma via Wnt/β-catenin pathway inactivation

CBX7, a member of the Polycomb-group proteins, plays a significant role in normal and cancerous tissues and has been defined as a tumor suppressor in thyroid, breast and pancreatic cancers. However, its function in glioma remains undefined. CBX7 expression is decreased in glioma, especially in higher grade cases, according to data in the CGGA, GSE16001 and TCGA databases. Further experimental evidence has shown that exogenous CBX7 overexpression induced apoptosis and inhibited cell proliferation, colony formation and migration of glioma cells. In this study, we show that the invasive ability of glioma cells was decreased following CBX7 overexpression and CBX7 overexpression was associated with Wnt/β-catenin pathway inhibition, which also decreased downstream expression of ZEB1, a core epithelial-to-mesenchymal transition factor. This reduction in Wnt signaling is controlled by DKK1, a specific Wnt/β-catenin inhibitor. CBX7 enhances DKK1 expression by binding the DKK1 promoter, as shown in Luciferase reporter assays. Our data confirm that CBX7 inhibits EMT and invasion in glioma, which is manifested by influencing the expression of MMP2, MMP9, E-cadherin, N-cadherin and Vimentin in LN229, T98G cells and primary glioma cells (PGC). Furthermore, as a tumor suppressor, CBX7 expression is pivotal to reduce tumor invasion and evaluate prognosis.

Cofilin 1 induces the epithelial-mesenchymal transition of gastric cancer cells by promoting cytoskeletal rearrangement

Epithelial-mesenchymal transition (EMT) is an important biological process whereby malignant tumor cells obtain the ability to migrate, invade, resist apoptosis and degrade the extracellular matrix. We found that Cofilin1 (CFL1) expression was elevated in clinical gastric cancer specimens and correlated with biomarkers of EMT in BGC-823 gastric cancer cells. BGC-823 cells exhibited EMT phenotypes and increased metastatic ability when induced by TGF-β1. By contrast, BGC-823 cells transfected with Lv-siRNA-CFL1 did not exhibit EMT phenotypes under the same inducing conditions. As CFL1 expression increased, EMT cell filopodia stretched out. In addition, the ultrastructures observed using transmission electron microscopy indicated that silencing of CFL1 markedly inhibited depolymerization of fibrous actin and cytoskeletal reorganization during EMT. Similar results were obtained in vivo. These findings demonstrate that CFL1 induces EMT by promoting cytoskeletal rearrangement. Our results may provide the basis for developing new anticancer drugs to inhibit CFL1.