Tissue factor pathway inhibitor-2 inhibits integrin ß1 activation and focal adhesion formation and suppresses peritoneal ovarian cancer dissemination in mice.

Tissue factor pathway inhibitor-2 (TFPI2) is a Kunitz-type serine protease inhibitor and an ovarian clear cell carcinoma (CCC) biomarker. TFPI2 is expressed in several cancers and exerts tumor-suppressive effects; however, the role of TFPI2 in the CCC cell phenotype remains unclear. Therefore, in this study, we investigated the function of TFPI2 by establishing a gene knockout (KO) in ES-2 CCC cells and observed the change in phenotypes in vitro and in vivo. TFPI2 KO inhibited ES-2 cell proliferation, increased extracellular matrix protein adhesion, enhanced focal adhesion formation and activated integrin ß1 cell surface clustering in vitro, and markedly increased ES-2 tumor growth and dissemination in the peritoneal cavity of a mouse xenograft model. These findings suggest a novel function of TFPI2 expression in suppressing the formation of focal adhesions in CCC cells, potentially by activating integrin ß1. This function plays a role in the peritoneal growth characteristics of CCC cells.

CD93 regulates breast cancer growth and vasculogenic mimicry through the PI3K/AKT/SP2 signaling pathway activated by integrin ß1.

In women, breast cancer (BC) accounts for 7%-10% of all cancer cases and is one of the most common cancers. To identify a new method for treating BC, the role of CD93 and its underlying mechanism were explored. MDA-MB-231 cells were used in this study and transfected with si-CD93, si-MMRN2, oe-CD93, si-integrin ß1, or oe-SP2 lentivirus. After MDA-MB-231 cells were transfected with si-NC or si-CD93, they were injected into nude mice by subcutaneous injection at a dose of 5 × 106/mouse to construct a BC animal model. The expression of genes and proteins and cell migration, invasion and vasculogenic mimicry were detected by RT‒qPCR, western blot, immunohistochemistry, immunofluorescence, Transwell, and angiogenesis assays. In pathological samples and BC cell lines, CD93 was highly expressed. Functionally, CD93 promoted the proliferation, migration, and vasculogenic mimicry of MDA-MB-231 cells. Moreover, CD93 interacts with MMRN2 and integrin ß1. Knockdown of CD93 and MMRN2 can inhibit the activation of integrin ß1, thereby inhibiting the PI3K/AKT/SP2 signaling pathway and inhibiting BC growth and vasculogenic mimicry. In conclusion, the binding of CD93 to MMRN2 can activate integrin ß1, thereby activating the PI3K/AKT/SP2 signaling pathway and subsequently promoting BC growth and vasculogenic mimicry.

The endothelial-to-mesenchymal transition changes the focal adhesion site proteins levels and the SLRP-lumican level in HMEC-1 cell line.

Scleroderma, the chronic autoimmune disease is a consequence of inflammation in the connective tissue. Prolonged duration affects formation of compact connective tissue strands (scarring) within the target organ. Endothelial cells undergoing endothelial-to-mesenchymal transition (EndMT) are the source of fibroblast phenotype-resembling cells. EndMT contributes to reorganization of the focal adhesion proteins (FA), including integrins, and intensive extracellular matrix (ECM) remodelling. However, in endothelial cells, the relationship between EndMT and the interaction of integrin receptors with lumican - a component of ECM, is still unclear. Our findings indicate that at the early stages of EndMT caused by Snail-1 transcription factor overexpression, the level of the ß1 integrin subunit and its phosphorylation are elevated. Simultaneously, the changes in the level of proteins that build FAs and promote activation of integrin receptors as well as a decrease in lumican quantity were observed. These modulations contributed to increased migration of human microvascular endothelial cells, HMEC-1. Our findings were achieved by WB, ELISA and wound healing assay. Taken altogether, transfection of HMEC-1 cells with Snail-1 plasmids inducing the early stages of EndMT results in the increase of total FAK and integrin ß1 phosphorylation as well as cell migration: phenomena which are modulated by interaction with lumican.

Sialylation on vesicular integrin ß1 determined endocytic entry of small extracellular vesicles into recipient cells.

BACKGROUND: Small extracellular vesicles (sEV) are closely associated with the development and metastasis of many types of mammalian cancer. Glycoconjugates are highly expressed on sEV and play important roles in sEV biogenesis and their interaction with other cells. However, the study on vesicular glycoconjugates are far behind proteins and nucleic acids. Especially, the functions of sialic acids which are the terminal components of glycoconjugates, are poorly understood in sEV. METHODS: Sialic acid levels on sEV from plasma and bladder cancer cells were determined by ELISA and lectin blotting. Effects of sialylation on sEV uptake were determined by flow cytometry. Vesicular glycoproteins bearing sialic acids responsible for sEV uptake was identified by proteomics and density gradient centrifugation, and their site-specific sialylation functions were assayed by N-glycosylation site mutation. Effects of integrin ß1 bearing sialic acids on the pro-metastatic function of sEV in vivo were explored using Balb/c nu/nu mice. RESULTS: (1) Increased sialic acid levels were observed in sEV from malignant bladder cancer cells. (2) Elimination of sialic acids on sEV impaired sEV uptake by recipient cells. (3) Vesicular integrin ß1 bearing sialic acids was identified to play a key role in sEV uptake. (4) Desialylation of the hybrid domain of vesicular integrin ß1 inhibited its binding to matrix fibronectin, and reduced sEV entry into recipient cells. (5) Sialylation on integrin ß1 affected pro-metastatic function of sEV in Balb/c nu/nu mice. CONCLUSIONS: Taken together, our findings indicate important functional roles of sialic acids in sEV uptake and reprogramming plasticity of surrounding normal epithelial cells.

Effect of Different Glucose Levels and Glycation on Meningioma Cell Migration and Invasion.

Meningiomas are predominantly benign tumors, but there are also malignant forms that are associated with a poor prognosis. Like almost all tumors, meningiomas metabolize glucose as part of aerobic glycolysis (Warburg effect) for energy supply, so there are attempts to influence the prognosis of tumor diseases using a glucose-reduced diet. This altered metabolism leads to so called hallmarks of cancer, such as glycation and glycosylation. In this study, we investigated the influence of low (3 mM), normal (5.5 mM) and high glucose (15 mM) on a malignant meningioma cell line (IOMM-Lee, WHO grade 3). In addition, the influence of methylglyoxal, a by-product of glycolysis and a precursor for glycation, was investigated. Impedance-based methods (ECIS and RTCA) were used to study migration and invasion, and immunoblotting was used to analyze the expression of proteins relevant to these processes, such as focal adhesion kinase (FAK), merlin or integrin ß1. We were able to show that low glucose reduced the invasive potential of the cells, which was associated with a reduced amount of sialic acid. Under high glucose, barrier function was impaired and adhesion decreased, which correlated with a decreased expression of FAK.

A Receptor Integrin ß1 Promotes Infection of Avian Metapneumovirus Subgroup C by Recognizing a Viral Fusion Protein RSD Motif.

Avian metapneumovirus subgroup C (aMPV/C) causes respiratory diseases and egg dropping in chickens and turkeys, resulting in severe economic losses to the poultry industry worldwide. Integrin ß1 (ITGB1), a transmembrane cell adhesion molecule, is present in various cells and mediates numerous viral infections. Herein, we demonstrate that ITGB1 is essential for aMPV/C infection in cultured DF-1 cells, as evidenced by the inhibition of viral binding by EDTA blockade, Arg-Ser-Asp (RSD) peptide, monoclonal antibody against ITGB1, and ITGB1 short interfering (si) RNA knockdown in cultured DF-1 cells. Simulation of the binding process between the aMPV/C fusion (F) protein and avian-derived ITGB1 using molecular dynamics showed that ITGB1 may be a host factor benefiting aMPV/C attachment or internalization. The transient expression of avian ITGB1-rendered porcine and feline non-permissive cells (DQ cells and CRFK cells, respectively) is susceptible to aMPV/C infection. Kinetic replication of aMPV/C in siRNA-knockdown cells revealed that ITGB1 plays an important role in aMPV/C infection at the early stage (attachment and internalization). aMPV/C was also able to efficiently infect human non-small cell lung cancer (A549) cells. This may be a consequence of the similar structures of both metapneumovirus F protein-specific motifs (RSD for aMPV/C and RGD for human metapneumovirus) recognized by ITGB1. Overexpression of avian-derived ITGB1 and human-derived ITGB1 in A549 cells enhanced aMPV/C infectivity. Taken together, this study demonstrated that ITGB1 acts as an essential receptor for aMPV/C attachment and internalization into host cells, facilitating aMPV/C infection.

FGFR2 Controls Growth, Adhesion and Migration of Nontumorigenic Human Mammary Epithelial Cells by Regulation of Integrin ß1 Degradation.

The role of fibroblast growth factor receptor 2 (FGFR2), an important mediator of stromal paracrine and autocrine signals, in mammary gland morphogenesis and breast cancer has been extensively studied over the last years. However, the function of FGFR2 signalling in the initiation of mammary epithelial oncogenic transformation remains elusive. Here, FGFR2-dependent behaviour of nontumorigenic model of mammary epithelial cells was studied. In vitro analyses demonstrated that FGFR2 regulates epithelial cell communication with extracellular matrix (ECM) proteins. Silencing of FGFR2 significantly changed the phenotype of cell colonies in three-dimensional cultures, decreased integrins α2, α5 and ß1 protein levels and affected integrin-driven processes, such as cell adhesion and migration. More detailed analysis revealed the FGFR2 knock-down-induced proteasomal degradation of integrin ß1. Analysis of RNA-seq databases showed significantly decreased FGFR2 and ITGB1 mRNA levels in breast tumour samples, when compared to non-transformed tissues. Additionally, high risk healthy individuals were found to have disrupted correlation profiles of genes associated with FGFR2 and integrin signalling, cell adhesion/migration and ECM remodelling. Taken together, our results strongly suggest that FGFR2 loss with concomitant integrin ß1 degradation is responsible for deregulation of epithelial cell-ECM interactions and this process may play an important role in the initiation of mammary gland epithelial tumorigenesis.

Tissue transglutaminase activates integrin-linked kinase and ß-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, where it interacts with fibronectin (FN) and the cell surface receptor integrin ß1. However, the mechanistic role of TG2 in cancer cell proliferation is unknown. Here, we demonstrate that TG2 directly interacts with and facilitates the phosphorylation and activation of the integrin effector protein integrin-linked kinase (ILK) at Ser246. We show that 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 that coexpression of TGM2 and ILK correlates with poor clinical outcome. Mechanistically, we demonstrate that TG2-mediated ILK activation causes phosphorylation of glycogen synthase kinase-3α/ß, allowing ß-catenin nuclear translocation and transcriptional activity. Furthermore, inhibition of TG2 and ILK using small molecules, neutralizing antibodies, or shRNA-mediated knockdown blocks 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 that TG2 directly interacts with and activates ILK in OC cells and tumors and define a new mechanism that links ECM cues with ß-catenin signaling in OC. These results suggest a central role of TG2-FN-integrin clusters in ECM rearrangement and indicate that downstream effector ILK may represent a potential new therapeutic target in OC.

The characteristics and the multiple functions of integrin ß1 in human cancers.

Integrins, which consist of two non-covalently linked α and ß subunits, play a crucial role in cell-cell adhesion and cell-extracellular matrix (ECM) interactions. Among them, integrin ß1 is the most common subunit and has emerged as a key mediator in cancer, influencing various aspects of cancer progression, including cell motility, adhesion, migration, proliferation, differentiation and chemotherapy resistance. However, given the complexity and sometimes contradictory characteristics, targeting integrin ß1 for therapeutics has been a challenge. The emerging understanding of the mechanisms regulating by integrin ß1 may guide the development of new strategies for anti-cancer therapy. In this review, we summarize the multiple functions of integrin ß1 and signaling pathways which underlie the involvement of integrin ß1 in several malignant cancers. Our review suggests the possibility of using integrin ß1 as a therapeutic target and highlights the need for patient stratification based on expression of different integrin receptors in future clinical studies.

Semaphorin 7A interacts with nuclear factor NF-kappa-B p105 via integrin ß1 and mediates inflammation.

Semaphorin7a (SEMA7A), a membrane-anchored member of the semaphorin protein family, could be involved in a diverse range of immune responses via its receptor integrin ß1. Recently, we reported that the SEMA7AR148W mutation (a gain-of-function mutation, Sema7aR145W in mice) is a risk factor for progressive familial intrahepatic cholestasis and nonalcoholic fatty liver disease via upregulated membrane localization. In this study, we demonstrated that integrin ß1 is a membrane receptor for nuclear factor NF-kappa-B p105 (NF-κB p105) and a critical mediator of inflammation. Integrin ß1 could interact with the C-terminal domain of NF-κB p105 to promote p50 generation and stimulate the NF-κB p50/p65 signalling pathway, upregulate TNF-α and IL-1ß levels, and subsequently render hepatocytes more susceptible to inflammation. The induction of integrin ß1 depends on elevated Sema7a membrane localization. Moreover, we revealed elevated levels of Sema7aWT (SEMA7AWT) in hepatocellular carcinoma (HCC) patients and an HCC mouse model. In line with our findings, the NF-κB p50/p65 pathway could also be activated by high Sema7a expression and repressed by integrin ß1 silencing. In conclusion, our findings suggest that the Sema7aR145W (SEMA7AR148W) mutation and high Sema7aWT (SEMA7AWT) expression both activate the NF-κB p50/p65 pathway via integrin ß1 and play a crucial role in inflammatory responses. Video Abstract.

Downregulation of glycoprotein non-metastatic melanoma protein B prevents high glucose-induced angiogenesis in diabetic retinopathy.

Diabetic retinopathy (DR), a microvascular complication characterized by abnormal angiogenesis, is the most common reason for irreversible blindness. Glycoprotein non-metastatic melanoma protein B (GPNMB), as a transmembrane protein, was found to be associated with angiogenesis. This study aims to investigate the role of GPNMB in DR. The levels of GPNMB and Integrin ß1 were detected by real-time PCR and western blot and were found to be increased in human retinal microvascular endothelial cells (HRMECs) with high glucose (HG, 25 mmol/L) treatment. Knockdown of GPNMB was mediated by lentivirus carrying shRNA targeting GPNMB in vivo and in vitro. Functional experiments, including cell counting kit-8 (CCK-8), scratch, and tube formation assays, showed the anti-proliferative, anti-migrative, and anti-angiogenic roles of GPNMB knockdown in HRMECs using the lentivirus system following HG challenge. Additionally, increased GPNMB levels were detected in the retina of DR rats induced by a single intraperitoneal injection of streptozotocin (60 mg/kg) using real-time PCR, western blot, and immunofluorescence assays. Downregulation of GPNMB inhibited the angiogenesis and vascular endothelial growth factor production in the retina of rats with DR. Furthermore, overexpression of Integrin ß1 led to increased angiogenesis in DR. Integrin ß1 was indicated as a target protein of GPNMB. Upregulated-Integrin ß1 restored GPNMB knockdown-induced inhibition of cell viability, migration, and tube formation in HRMECs. In conclusion, we provide evidence for the angiogenic role of GPNMB and demonstrate that silencing GPNMB may represent a therapeutic potential in the treatment of DR.

Heart Failure Promotes Cancer Progression in an Integrin ß1-Dependent Manner.

Heart failure and cancer are currently the deadliest diseases in the Western world, posing the most pressing clinical challenges that remain unmet today. Both conditions share similar risk factors, including age, genetics, lifestyle, chronic inflammation, stress, and more. Furthermore, medications that are being used to counteract cancer frequently result in cardiotoxicity and the spontaneous emergence of heart failure. Thus, heart failure and cancer display an intimate connection and share similarities. Recent studies show that cardiac remodeling and heart failure promote cancer progression and metastasis. Using three different mouse models for heart failure revealed that the communication between the remodeled heart and the tumor is facilitated through multiple secreted factors. Among these factors, Periostin was consistently found to be elevated in all models and was shown to be required in vitro. Yet, whether Periostin is necessary for tumor promotion in vivo is unknown. Towards this end, we examined tumor promotion in mice lacking Periostin following transverse aortic constriction (TAC). Despite the loss of Periostin, tumor growth was promoted in the TAC-operated mice. This likely occurred due to increased levels of various cytokines and growth factors in Periostin KO mice. Many of these factors are potential ligands of Integrin receptors. Therefore, we next studied the role of Integrin receptors in the tumor-promotion phenotype following heart failure. We generated cancer cells with an Integrin ß1 loss of function mutation and examined tumor growth in the presence and absence of heart failure. Integrin ß1 KO cancer cells fail to display cardiac-remodeling-dependent tumor-promotion. Interestingly, a previous study showed that renal cell carcinoma cells (Renca) fail to be promoted following a myocardial infarction. Consistently, we show that Renca cells do not respond to secreted factors derived from the failing heart both in vitro and in vivo. Interestingly, Renca cells display low basal mRNA levels of Integrin ß1 which may explain the inability of heart failure to promote their growth. The findings may have significant clinical relevance to cardio-oncology patients who suffer from cancers with high levels of Integrin ß1. Chemotherapy leading to cardiotoxicity in these patients may generate a vicious cycle with poor prognosis.

Broussonin A- and B-mediated inhibition of angiogenesis by blockade of VEGFR-2 signalling pathways and integrin ß1 expression.

In the present study, we demonstrate the regulatory effects and mechanism of broussonin A and B, diphenylpropane derivatives isolated from Broussonetia kazinoki, on vascular endothelial growth factor-A (VEGF-A)-stimulated endothelial cell responses in vitro and microvessel sprouting ex vivo. Treatment with broussonin A or B suppressed VEGF-A-stimulated endothelial cell proliferation by regulating the expression of cell cycle-related proteins and the phosphorylation status of retinoblastoma protein. In addition, treatment with broussonin A or B abrogated VEGF-A-stimulated angiogenic responses including endothelial cell migration, invasion, tube formation and microvessel formation from rat aortic rings. These anti-angiogenic activities of broussonin A and B were mediated through inactivation of VEGF-A-stimulated downstream signalling pathways, localization of vascular endothelial-cadherin at cell-cell contacts, and down-regulation of integrin ß1 and integrin-liked kinase. Furthermore, treatment with broussonin A or B inhibited proliferation and invasion of non-small cell lung cancer and ovarian cancer cells. Taken together, our findings suggest the pharmacological potential of broussonin A and B in the regulation of angiogenesis, cancer cell growth and progression.

An ancient interleukin-16-like molecule regulates hemocyte proliferation via integrin ß1 in invertebrates.

Interleukins (ILs) are cytokines with crucial functions in innate and adaptive immunity. IL genes are only found in vertebrates, except for IL-16, which has been cloned in some arthropod species. However, the function of this gene in invertebrates is unknown. In the present study, an IL-16-like gene (EsIL-16) was identified from the Chinese mitten crab Eriocheir sinensis. EsIL-16 was predicted to encode a precursor (proEsIL-16) that shares similarities with pro-IL-16 proteins from insects and vertebrates. We show that caspase-3 processes proEsIL-16 into an approximately 144-kDa N-terminal prodomain with nuclear import activity and an approximately 34-kDa mature peptide that might be secreted into the extracellular region. EsIL-16 mRNA could be detected in all analyzed tissues and was significantly upregulated after immune challenge both in vitro and in vivo. T7 phage display library screening suggested potential binding activity between EsIL-16 and integrin, which was confirmed by coimmunoprecipitation assay. Interestingly, EsIL-16 promoted cell proliferation via integrin ß1 in primary cultured crab hemocytes and Drosophila S2 cells. Furthermore, the interaction between EsIL-16 and integrin ß1 was necessary to efficiently protect the host from bacterial infection. To our knowledge, this study revealed integrin ß1 as a receptor for IL-16 and the function of this interaction in hemocyte proliferation in invertebrates for the first time. These results provide new insights into the regulation of innate immune responses in invertebrates and shed the light on the evolution of ILs within the animal kingdom.

The expression of BMP, integrin, ZEB2 in ovarian high-grade serous carcinoma in relation with lymph node metastasis.

Ovarian cancer (OC) is clinically important because it is diagnosed late and has metastasis when it is diagnosed. Mortality risk increases 2.75 times in the presence of lymph node (LN) metastasis. During metastasis, many molecules including BMPs originated from stroma, and tumor cells participate through transcription factors and integrins for cytoskeleton regulation during cell migration. We hypothesized an inverse correlation between BMP2 and BMP7 along with changes in ZEB2, and integrin α5ß1 in high-grade OCs in relation to LN metastasis. The BMP2 immunoreactivity was strong along with strong ZEB2 and weak integrins' immunoreactivity in samples with LN metastasis. Strong immunoreactivity of BMP7 was accompanied by strong immunoreactivity of integrins in the samples without LN metastasis. Study results showed BMP2's strong positive immunoreactivity and weak BMP7 immunoreactivity in tumor cells with a significantly weak inverse correlation. This inverse correlation should be considered as both BMPs have different effects in the window of cancer progression and invasion.

3D matrix promotes cell dedifferentiation into colorectal cancer stem cells via integrin/cytoskeleton/glycolysis signaling.

The potential for tumor occurrence triggered by cancer stem cells (CSCs) has emerged as a significant challenge for human colorectal cancer therapy. However, the underlying mechanism of CSC development remains controversial. Our study provided evidence that the bulk of tumor cells could dedifferentiate to CSCs and reacquire CSC-like phenotypes if cultured in the presence of extracellular matrix reagents, such as Matrigel and fibrin gels. In these 3D gels, CD133- colorectal cancer cells can regain tumorigenic potential and stem-like phenotypes. Mechanistically, the 3D extracellular matrix could mediate cytoskeletal F-actin bundling through biomechanical force associated receptors integrin ß1 (ITGB1), contributing to the release of E3 ligase tripartite motif protein 11 (TRIM11) from cytoskeleton and degradation of the glycolytic rate-limiting enzyme phosphofructokinase (PFK). Consequently, PFK inhibition resulted in enhanced glycolysis and upregulation of hypoxia-inducible factor 1 (HIF1α), thereby promoting the reprogramming of stem cell transcription factors and facilitating tumor progression in patients. This study provided novel insights into the role of the extracellular matrix in the regulation of CSC dedifferentiation in a cytoskeleton/glycolysis-dependent manner.

Extracellular ATP promotes angiogenesis and adhesion of TNBC cells to endothelial cells via upregulation of CTGF.

Our previous works have indicated that extracellular ATP is an important prometastasis factor. However, the molecular mechanism involved needs to be further studied. We demonstrated that extracellular ATP treatment could upregulate the expression of connective tissue growth factor (CTGF) in both triple-negative breast cancer (TNBC) cells and endothelial cells (ECs). Extracellular ATP stimulated the migration of TNBC cells and ECs, and angiogenesis of ECs via the P2Y2--YAP-CTGF axis. Furthermore, we demonstrated that adenosine triphosphate (ATP) stimulated TNBC cell adhesion to ECs and transmigration through the EC layer via CTGF by upregulation of integrin ß1 on TNBC cells and VCAM-1 on ECs. Both apyrase (ATP-diphosphohydrolase) and CTGF shRNA treatments could inhibit the metastasis of inoculated tumors to lung and liver in a mouse model, and these treated tumors had fewer blood vessels. Collectively, our data indicated that extracellular ATP promotes tumor angiogenesis and the interactions between TNBC cells and ECs through upregulation of CTGF, thereby stimulating TNBC metastasis. The pleiotropic effects of ATP in angiogenesis and cell adhesion suggest that extracellular ATP or CTGF could be an effective target for TNBC therapy.

Drebrin promotes lung adenocarcinoma cell migration through inducing integrin ß1 endocytosis.

Lung adenocarcinoma (LUAD) is the most common type of lung cancers, which remains the leading cause of cancer-related death worldwide. Drebrin can promote cell migration and invasion with poor prognosis, but its roes in LUAD tumor progression remains unknown. We showed that the expression of Drebrin was upregulated in clinical LUAD samples. A Kaplan-Meier survival analysis showed that a high expression of Drebrin predicated poor prognosis in LUAD. In vitro, Drebrin promoted anchorage-independent growth and migration of LUAD cells. Drebrin interacted with dynamin through CT domain, and served as an adaptor to promote LUAD cell migration through inducing integrin ß1 endocytosis. Thus, this study demonstrated the critical role of Drebrin in LUAD and associated mechanism.

Tetraspanin 7 promotes osteosarcoma cell invasion and metastasis by inducing EMT and activating the FAK-Src-Ras-ERK1/2 signaling pathway.

BACKGROUND: Tetraspanins are members of the 4-transmembrane protein superfamily (TM4SF) that function by recruiting many cell surface receptors and signaling proteins into tetraspanin-enriched microdomains (TEMs) that play vital roles in the regulation of key cellular processes including adhesion, motility, and proliferation. Tetraspanin7 (Tspan7) is a member of this superfamily that plays documented roles in hippocampal neurogenesis, synaptic transmission, and malignant transformation in certain tumor types. How Tspan7 influences the onset or progression of osteosarcoma (OS), however, remains to be defined. Herein, this study aimed to explore the relationship between Tspan7 and the malignant progression of OS, and its underlying mechanism of action. METHODS: In this study, the levels of Tspan7 expression in human OS cell lines were evaluated via qRT-PCR and western blotting. The effect of Tspan7 on proliferation was examined using CCK-8 and colony formation assays, while metastatic role of Tspan7 was assessed by functional assays both in vitro and in vivo. In addition, mass spectrometry and co-immunoprecipitation were performed to verify the interaction between Tspan7 and ß1 integrin, and western blotting was used to explore the mechanisms of Tspan7 in OS progresses. RESULTS: We found that Tspan7 is highly expressed in primary OS tumors and OS cell lines. Downregulation of Tspan7 significantly suppressed OS growth, metastasis, and attenuated epithelial-mesenchymal transition (EMT), while its overexpression had the opposite effects in vitro. Furthermore, it exhibited reduced OS pulmonary metastases in Tspan7-deleted mice comparing control mice in vivo. Additionally, we proved that Tspan7 interacted with ß1 integrin to facilitate OS metastasis through the activation of integrin-mediated downstream FAK-Src-Ras-ERK1/2 signaling pathway. CONCLUSION: In summary, this study demonstrates for the first time that Tspan7 promotes OS metastasis via interacting with ß1 integrin and activating the FAK-Src-Ras-ERK1/2 pathway, which could provide rationale for a new therapeutic strategy for OS.

Integrin ß1 orchestrates the abnormal cell-matrix attachment and invasive behaviour of E-cadherin dysfunctional cells.

BACKGROUND: Tumour progression relies on the ability of cancer cells to penetrate and invade neighbouring tissues. E-cadherin loss is associated with increased cell invasion in gastric carcinoma, and germline mutations of the E-cadherin gene are causative of hereditary diffuse gastric cancer. Although E-cadherin dysfunction impacts cell-cell adhesion, cell dissemination also requires an imbalance of adhesion to the extracellular matrix (ECM). METHODS: To identify ECM components and receptors relevant for adhesion of E-cadherin dysfunctional cells, we implemented a novel ECM microarray platform coupled with molecular interaction networks. The functional role of putative candidates was determined by combining micropattern traction microscopy, protein modulation and in vivo approaches, as well as transcriptomic data of 262 gastric carcinoma samples, retrieved from the cancer genome atlas (TCGA). RESULTS: Here, we show that E-cadherin mutations induce an abnormal interplay of cells with specific components of the ECM, which encompasses increased traction forces and Integrin ß1 activation. Integrin ß1 synergizes with E-cadherin dysfunction, promoting cell scattering and invasion. The significance of the E-cadherin-Integrin ß1 crosstalk was validated in Drosophila models and found to be consistent with evidence from human gastric carcinomas, where increased tumour grade and poor survival are associated with low E-cadherin and high Integrin ß1 levels. CONCLUSIONS: Integrin ß1 is a key mediator of invasion in carcinomas with E-cadherin impairment and should be regarded as a biomarker of poor prognosis in gastric cancer.