Inhibition of αvβ3 integrin induces loss of cell directionality of oral squamous carcinoma cells (OSCC)

Disintegrin Accutin inhibits A549 cell migration though suppression of EMT and FAK/AKT signaling pathway

Integrins are heterodimers composed of two subunits, α(120-185kD) and β (90-110kD), which mediate the connection between cells and their external environment, such as extracellular matrix (ECM), and play an important role in the regulation of cell shape, proliferation and migration. Herein, we identified a potent anti-tumor migration peptide Accutin from crude venom of Agkistrodon acutus using an A549 3D tumor sphere model, and simulation tools and RNA sequencing were performed to reveal the mechanism of Accutin. Accutin is a disintegrin and docking, molecular dynamics simulations and ITC assay indicate that the RGD motif in the Accutin sequence can stably bind to integrins α5β1. 9.22 nM Accutin can significantly inhibit the migration and invasion of lung cancer cell lines. Transcriptome analysis indicated that many genes are involved in tumor cell adhesion-related biological processes. Several pathways, like the "mTOR signaling pathway", "TGF-β signaling pathway", and "Focal adhesion" were enriched. Interestingly, pathways involved in "N-Glycan biosynthesis" etc. were significantly inhibited. These transcriptomics data suggested that the molecular basis of Accutin-mediated inhibition of cancer cell migration may be by inhibiting N-glycosylation of integrin, then inhibiting signaling pathways such as PI3K/AKT/mTOR and TGFβ/smad. Western blotting analysis further confirmed that Accutin could suppress migration via down-regulating the phosphorylation of FAK and AKT and inhibiting EMT (epithelial-mesenchymal transition). Taken together, as a disintegrin with high efficiency, Accutin may be a potential precursor of a therapeutic agent for the treatment of lung cancer migration.

Blockage of αvβ3 integrin in 3D culture of triple-negative breast cancer and endothelial cells inhibits migration and discourages endothelial-to-mesenchymal plasticity

Breast cancer is a relevant cause of mortality in women and its triple-negative subtype (TNBC) is usually associated with poor prognosis. During tumor progression to metastasis, angiogenesis is triggered by the sprouting of endothelial cells from pre-existing vessels by a dynamic chain of events including VE-cadherin downregulation, actin protrusion, and integrin-mediated adhesion, allowing for migration and proliferation. The binding of tumoral and tumor-associated stromal cells with the extracellular matrix through integrins mediates angiogenic processes and certain integrin subtypes, such as the αvβ3 integrin, are upregulated in hypoxic TNBC models. Integrin αvβ3 inhibition by the high-affinity binding disintegrin DisBa-01 was previously demonstrated to induce anti-tumoral and anti-angiogenic responses in traditional 2D cell assays. Here, we investigate the effects of integrin αvβ3 blockage in endothelial and TNBC cells by DisBa-01 in 3D cultures under two oxygen conditions (1% and 20%). 3D cultures created using non-adhesive micromolds with Matrigel were submitted to migration assay in Boyden chambers and fluorescence analysis. DisBa-01 inhibited cell migration in normoxia and hypoxia in both MDA-MB-231 and HUVEC spheroids. Protein levels of integrin αvβ3 were overexpressed in HUVEC spheroids compared to MDA-MB-231 spheroids. In HUVEC 3D cultures, sprouting assays in collagen type I were decreased in normoxia upon DisBa-01 treatment, and VE-cadherin levels were diminished in HUVEC spheroids in hypoxia and upon DisBa-01 treatment. In conclusion, the blockage of integrin αvβ3 by DisBa-01 inhibits cell migration in 3D culture and interferes with tumor-derived responses in different oxygen settings, implicating its crucial role in angiogenesis and tumor progression.

The Role of αvβ3 Integrin in Cancer Therapy Resistance

A relevant challenge for the treatment of patients with neoplasia is the development of resistance to chemo-, immune-, and radiotherapies. Although the causes of therapy resistance are poorly understood, evidence suggests it relies on compensatory mechanisms that cells develop to replace specific intracellular signaling that should be inactive after pharmacological inhibition. One such mechanism involves integrins, membrane receptors that connect cells to the extracellular matrix and have a crucial role in cell migration. The blockage of one specific type of integrin is frequently compensated by the overexpression of another integrin dimer, generally supporting cell adhesion and migration. In particular, integrin αvβ3 is a key receptor involved in tumor resistance to treatments with tyrosine kinase inhibitors, immune checkpoint inhibitors, and radiotherapy; however, the specific inhibition of the αvβ3 integrin is not enough to avoid tumor relapse. Here, we review the role of integrin αvβ3 in tumor resistance to therapy and the mechanisms that have been proposed thus far. Despite our focus on the αvβ3 integrin, it is important to note that other integrins have also been implicated in drug resistance and that the collaborative action between these receptors should not be neglected.

Contact Guidance of Connective Tissue Fibroblasts on Submicrometer Anisotropic Topographical Cues Is Dependent on Tissue of Origin, β1 Integrins, and Tensin-1 Recruitment

The substratum topography of both natural and synthetic materials is a prominent regulator of cell behaviors including adhesion, migration, matrix fibrillogenesis, and cell phenotype. Connective tissue fibroblasts are known to respond to repeating groove topographical modifications by aligning and exhibiting directed migration, a phenomenon termed contact guidance. Although both reside in collagen rich connective tissues, dermal and gingival fibroblasts are known to exhibit differences in phenotype during wound healing, with gingival tissue showing a fetal-like scarless response. Differences in adhesion formation and maturation are known to underlie both a scarring phenotype and cell response to topographical features. Utilizing repeating groove substrates with periodicities of 600, 900, and 1200 nm (depth, 100 nm), we investigated the roles of integrins αvβ3 and β1 associated adhesions on contact guidance of human gingival (HGFs) and dermal fibroblasts (HDFs). HGFs showed a higher degree of orientation with the groove long axis than HDFs, with alignment of both vinculin and tensin-1 evident on 600 and 900 nm periodicities in both cell types. Orientation with grooves of any periodicity in HGFs and HDFs did not alter the adhesion number or area compared to smooth control surfaces. Growth of both cell types on all periodicities reduced fibronectin fibrillogenesis compared to control surfaces. Independent inhibition of integrin αvβ3 and β1 in both cell types induced changes in spreading up to 6 h and reduced alignment with the groove long axis. At 24 h post-seeding with blocking antibodies, HGFs recovered orientation, but in HDFs, blocking of β1, but not αvβ3 integrins, inhibited alignment. Blocking of β1 and αvβ3 in HDFs, but not HGFs, inhibited tensin-1-associated fibrillar adhesion formation. Furthermore, inhibition of β1 integrins in HDFs, but not HGFs, resulted in recruitment of tensin-1 to αvβ3 focal adhesions, preventing HDFs from aligning with the groove long axis. Our work demonstrates that tensin-1 localization with specific integrins in adhesion sites is an important determinant of contact guidance. This work emphasizes further the need for tissue-specific biomaterials, when integration into host tissues is required.

An integrative web-based software tool for multi-dimensional pathology whole-slide image analytics

Objective.In the era of precision medicine, human tumor atlas-oriented studies have been significantly facilitated by high-resolution, multi-modal tissue based microscopic pathology image analytics. To better support such tissue-based investigations, we have developed Digital Pathology Laboratory (DPLab), a publicly available web-based platform, to assist biomedical research groups, non-technical end users, and clinicians for pathology whole-slide image visualization, annotation, analysis, and sharing via web browsers.Approach.A major advancement of this work is the easy-to-follow methods to reconstruct three-dimension (3D) tissue image volumes by registering two-dimension (2D) whole-slide pathology images of serial tissue sections stained by hematoxylin and eosin (H&E), and immunohistochemistry (IHC). The integration of these serial slides stained by different methods provides cellular phenotype and pathophysiologic states in the context of a 3D tissue micro-environment. DPLab is hosted on a publicly accessible server and connected to a backend computational cluster for intensive image analysis computations, with results visualized, downloaded, and shared via a web interface.Main results.Equipped with an analysis toolbox of numerous image processing algorithms, DPLab supports continued integration of community-contributed algorithms and presents an effective solution to improve the accessibility and dissemination of image analysis algorithms by research communities.Significance.DPLab represents the first step in making next generation tissue investigation tools widely available to the research community, enabling and facilitating discovery of clinically relevant disease mechanisms in a digital 3D tissue space.

Small Extracellular Vesicles from Hypoxic Triple-Negative Breast Cancer Cells Induce Oxygen-Dependent Cell Invasion

Hypoxia, a condition of low oxygenation frequently found in triple-negative breast tumors (TNBC), promotes extracellular vesicle (EV) secretion and favors cell invasion, a complex process in which cell morphology is altered, dynamic focal adhesion spots are created, and ECM is remodeled. Here, we investigated the invasive properties triggered by TNBC-derived hypoxic small EV (SEVh) in vitro in cells cultured under hypoxic (1% O₂) and normoxic (20% O₂) conditions, using phenotypical and proteomic approaches. SEVh characterization demonstrated increased protein abundance and diversity over normoxic SEV (SEVn), with enrichment in pro-invasive pathways. In normoxic cells, SEVh promotes invasive behavior through pro-migratory morphology, invadopodia development, ECM degradation, and matrix metalloprotease (MMP) secretion. The proteome profiling of 20% O₂-cultured cells exposed to SEVh determined enrichment in metabolic processes and cell cycles, modulating cell health to escape apoptotic pathways. In hypoxia, SEVh was responsible for proteolytic and catabolic pathway inducement, interfering with integrin availability and gelatinase expression. Overall, our results demonstrate the importance of hypoxic signaling via SEV in tumors for the early establishment of metastasis.

The Effects of αvβ3 Integrin Blockage in Breast Tumor and Endothelial Cells under Hypoxia In Vitro

Breast cancer is characterized by a hypoxic microenvironment inside the tumor mass, contributing to cell metastatic behavior. Hypoxia induces the expression of hypoxia-inducible factor (HIF-1α), a transcription factor for genes involved in angiogenesis and metastatic behavior, including the vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMPs), and integrins. Integrin receptors play a key role in cell adhesion and migration, being considered targets for metastasis prevention. We investigated the migratory behavior of hypoxia-cultured triple-negative breast cancer cells (TNBC) and endothelial cells (HUVEC) upon αvβ3 integrin blocking with DisBa-01, an RGD disintegrin with high affinity to this integrin. Boyden chamber, HUVEC transmigration, and wound healing assays in the presence of DisBa-01 were performed in hypoxic conditions. DisBa-01 produced similar effects in the two oxygen conditions in the Boyden chamber and transmigration assays. In the wound healing assay, hypoxia abolished DisBa-01′s inhibitory effect on cell motility and decreased the MMP-9 activity of conditioned media. These results indicate that αvβ3 integrin function in cell motility depends on the assay and oxygen levels, and higher inhibitor concentrations may be necessary to achieve the same inhibitory effect as in normoxia. These versatile responses add more complexity to the role of the αvβ3 integrin during tumor progression.

Moxifloxacin induces random migration in human corneal fibroblasts via the protein kinase C epsilon/zonula occludens-1 signaling pathway

Moxifloxacin (MOX) suppresses cell movement in human corneal fibroblasts (HCFs). Zonula occludens-1 (ZO-1) is localized to the leading edge of migrating HCFs. This study explored the role of ZO-1 in MOX-suppressed cell migration in HCFs. A single-cell trajectory analysis revealed that MOX negatively regulated the migratory properties of HCFs including migration distance, migration velocity, and directionality (P < 0.001, P < 0.001, and P = 0.018, respectively). MOX increased endogenous ZO-1 in HCFs in a concentration-dependent manner (P = 0.083, P = 0.005, and P = 0.001 at 10, 50, and 100 μg/ml, respectively), but decreased the phosphorylation of endogenous ZO-1 at serines, threonines, and tyrosines. In contrast, MOX did not alter the expression of protein kinase C epsilon (PKCε), Rac-1, Cdc42, and MRCKβ. However, MOX did also reduce the phosphorylation level of PKCε at serines and threonines (P < 0.001 at 100 μg/ml). In addition, MOX increased the phosphorylation level of Rac-1 in a concentration-dependent manner (P < 0.001 at 100 μg/ml). Compared with the mock cells, the directionality of cell movement increased significantly in ZO-1-expressing HCFs (P = 0.012) and decreased significantly in ZO-1-silenced HCFs (P = 0.002). The directionality did not change significantly in Rac-1-silenced HCFs. ZO-1-expressing HCFs moved faster than mock cells. PKCε, Cdc42, Rac-1, and phosphorylated Rac-1 were decreased in ZO-1-overexpressing HCFs, but increased in ZO-1-silenced HCFs. Finally, silencing ZO-1 blocked MOX hyperactivation of Rac-1. These suggest that MOX might trigger random migration in human corneal stromal cells through PKCε-modulated ZO-1 inactivation and Rac-1 hyperactivation.

Inhibition of αvβ3 integrin impairs adhesion and uptake of tumor-derived small extracellular vesicles

BACKGROUND

Extracellular vesicles (EVs) are lipid-bound particles that are naturally released from cells and mediate cell-cell communication. Integrin adhesion receptors are enriched in small EVs (SEVs) and SEV-carried integrins have been shown to promote cancer cell migration and to mediate organ-specific metastasis; however, how integrins mediate these effects is not entirely clear and could represent a combination of EV binding to extracellular matrix and cells.

METHODS

To probe integrin role in EVs binding and uptake, we employed a disintegrin inhibitor (DisBa-01) of integrin binding with specificity for αvβ3 integrin. EVs were purified from MDA-MB-231 cells conditioned media by serial centrifugation method. Isolated EVs were characterized by different techniques and further employed in adhesion, uptake and co-culture experiments.

RESULTS

We find that SEVs secreted from MDA-MB-231 breast cancer cells carry αvβ3 integrin and bind directly to fibronectin-coated plates, which is inhibited by DisBa-01. SEV coating on tissue culture plates also induces adhesion of MDA-MB-231 cells, which is inhibited by DisBa-01 treatment. Analysis of EV uptake and interchange between cells reveals that the amount of CD63-positive EVs delivered from malignant MDA-MB-231 breast cells to non-malignant MCF10A breast epithelial cells is reduced by DisBa-01 treatment. Inhibition of αvβ3 integrin decreases CD63 expression in cancer cells suggesting an effect on SEV content.

CONCLUSION

In summary, our findings demonstrate for the first time a key role of αvβ3 integrin in cell-cell communication through SEVs. Video Abstract.

Snake Venom Metalloproteinases (SVMPs): A structure-function update

Snake venom metalloproteinases (SVMPs) represent a diverse group of multi-domain proteins with several biological activities such as the ability to induce hemorrhage, proteolytic degradation of fibrinogen and fibrin, induction of apoptosis and inhibition of platelet aggregation. Due to these activities, SVMPs are responsible for many of the well-known pathological phenotypes in snake envenomations caused particularly by species from the Viperidae family and the Crotalinae subfamily. These proteins have been classified based on their size and domain structure into P–I, P-II and P-III classes. Comparatively, members of the P–I SVMPs possess the simplest structures, formed by the catalytic metalloproteinase domain only; the P-II SVMPs are moderately more complex, having the canonical disintegrin domain in addition to the metalloproteinase domain; members of the P-III class are more structurally varied, comprising the metalloproteinase, disintegrin-like, and cysteine-rich domains. Proteolytic cleavage, repeated domain loss and presence of other ancillary domains are responsible for structural diversities in the P-III class. However, studies continue to unveil the relationship between the structure and function of these proteins. In this review, we recovered evidences from literature on the structural peculiarities and functional classification of Snake Venom Metalloproteinases. In addition, we reflect on diversities that exist among each class while taking into account specific and up-to-date class-based activities.

Putting the brakes on tumorigenesis with snake venom toxins: New molecular insights for cancer drug discovery

Cancer cells exhibit molecular characteristics that confer them different proliferative capacities and survival advantages to adapt to stress conditions, such as deregulation of cellular bioenergetics, genomic instability, ability to promote angiogenesis, invasion, cell dormancy, immune evasion, and cell death resistance. In addition to these hallmarks of cancer, the current cytostatic drugs target the proliferation of malignant cells, being ineffective in metastatic disease. These aspects highlight the need to identify promising therapeutic targets for new generations of anti-cancer drugs. Toxins isolated from snake venoms are a natural source of useful molecular scaffolds to obtain agents with a selective effect on cancer cells. In this article, we discuss the recent advances in the molecular mechanisms of nine classes of snake toxins that suppress the hallmarks of cancer by induction of oxidative phosphorylation dysfunction, reactive oxygen species-dependent DNA damage, blockage of extracellular matrix-integrin signaling, disruption of cytoskeleton network and inhibition of growth factor-dependent signaling. The possible therapeutic implications of toxin-based anti-cancer drug development are also highlighted.

Alphavbeta3 integrin blocking inhibits apoptosis and induces autophagy in murine breast tumor cells

Integrins are cell receptors that mediate adhesion to the extracellular matrix (ECM) and regulate cell migration, a crucial process in tumor invasion. The α_vβ₃ integrin recognizes the arginine-glycine-aspartic acid (RGD) motif in ECM proteins and it can be antagonized by RGD-peptides, resulting in decreased cell migration and invasion. RGD-based drugs have shown disappointing results in clinical trials; however, the reasons for their lack of activity are still obscure. Aiming to contribute to a better understanding of the molecular consequences of integrin inhibition, we tested a recombinant RGD-disintegrin (DisBa-01) in two types of murine cell lines, breast tumor 4T1BM2 cells and L929 fibroblasts. Only tumor cells showed decreased motility and adhesion, as well as morphologic alterations upon DisBa-01 treatment (100 and 1000 nM). This result was attributed to the higher levels of α_vβ₃ integrin in 4T1BM2 cells compared to L929 fibroblasts making the former more sensitive to DisBa-01 blocking. DisBa-01 induced cell cycle arrest at the S phase in 4T1BM2 cells, but it did not induce apoptosis, which was consistent with the decrease in caspase-3, 8 and 9 expression at mRNA and protein levels. DisBa-01 increases PI3K, Beclin-1 and LC3B expression in tumor cells, indicators of autophagic induction. In conclusion, α_vβ₃ integrin blocking by DisBa-01 results in inhibition of adhesion and migration and in the activation of an autophagy program, allowing prolonged survival and avoiding immediate apoptotic death. These observations suggest new insights into the effects of RGD-based inhibitors considering their importance in drug development for human health.

Development of upconversion nanoparticle-conjugated indium phosphide quantum dot for matrix metalloproteinase-2 cancer transformation sensing

Aim: Matrix metalloproteinase-2 (MMP2) plays an important role in extracellular matrix remodeling, that is, it increases significantly during cancer progression. In this regard, MMP2 monitoring is important. Experiment: A well-designed MMP2-sensitive polypeptide chain was used to link indium phosphide quantum dots (InP QDs) with upconversion nanoparticles (UCNPs) to form a nanocomposite that was utilized as biosensor. Results: We produced a biosensor that can be recognized by MMP2 and determined the presence or absence of MMP2 in cells by identifying difference in fluorescence wavelength. The InP QDs modified the arginylglycylaspartic acid molecules as targeting ligand based on chitosan. Conclusion: The MMP2-based biosensor, named UCNP-p@InP-cRGD, is sensitive and can be applied for biosensing probes.

Hernia and Cancer: The Points Where the Roads Intersect

Introduction: This review aimed to present common points, intersections, and potential interactions or mutual effects for hernia and cancer. Besides direct relationships, indirect connections, and possible involvements were searched. Materials and Methods: A literature search of PubMed database was performed in July 2018 as well as a search of relevant journals and reference lists. The total number of screened articles was 1,422. Some articles were found in multiple different searches. A last PubMed search was performed during manuscript writing in December 2018 to update the knowledge. Eventually 427 articles with full text were evaluated, and 264 included, in this review. Results: There is no real evidence for a possible common etiology for abdominal wall hernias and any cancer type. The two different diseases had been found to have some common points in the studies on genes, integrins, and biomarkers, however, to date no meaningful relationship has been identified between these points. There is also some, albeit rather conflicting, evidence for inguinal hernia being a possible risk factor for testicular cancer. Neoadjuvant or adjuvant therapeutic modalities like chemotherapy and radiotherapy may cause postoperative herniation with their adverse effects on tissue repair. Certain specific substances like bevacizumab may cause more serious complications and interfere with hernia repair. There are only two articles in PubMed directly related to the topic of "hernia and cancer." In one of these the authors claimed that there was no association between cancer development and hernia repair with mesh. The other article reported two cases of squamous-cell carcinoma developed secondary to longstanding mesh infections. Conclusion: As expected, the relationship between abdominal wall hernias and cancer is weak. Hernia repair with mesh does not cause cancer, there is only one case report on cancer development following a longstanding prosthetic material infections. However, there are some intersection points between these two disease groups which are worthy of research in the future.

Recombinant RGD-disintegrin DisBa-01 blocks integrin αvβ3 and impairs VEGF signaling in endothelial cells

Background

Integrins mediate cell adhesion, migration, and survival by connecting the intracellular machinery with the surrounding extracellular matrix. Previous studies demonstrated the interaction between α_vβ₃ integrin and VEGF type 2 receptor (VEGFR2) in VEGF-induced angiogenesis. DisBa-01, a recombinant His-tag fusion, RGD-disintegrin from Bothrops alternatus snake venom, binds to α_vβ₃ integrin with nanomolar affinity blocking cell adhesion to the extracellular matrix. Here we present in vitro evidence of a direct interference of DisBa-01 with α_vβ₃/VEGFR2 cross-talk and its downstream pathways.

Methods

Human umbilical vein (HUVECs) were cultured in plates coated with fibronectin (FN) or vitronectin (VN) and tested for migration, invasion and proliferation assays in the presence of VEGF, DisBa-01 (1000 nM) or VEGF and DisBa-01 simultaneously. Phosphorylation of α_vβ₃/VEGFR2 receptors and the activation of intracellular signaling pathways were analyzed by western blotting. Morphological alterations were observed and quantified by fluorescence confocal microscopy.

Results

DisBa-01 treatment of endothelial cells inhibited critical steps of VEGF-mediated angiogenesis such as migration, invasion and tubulogenesis. The blockage of α_vβ₃/VEGFR2 cross-talk by this disintegrin decreases protein expression and phosphorylation of VEGFR2 and β₃ integrin subunit, regulates FAK/SrC/Paxillin downstream signals, and inhibits ERK1/2 and PI3K pathways. These events result in actin re-organization and inhibition of HUVEC migration and adhesion. Labelled-DisBa-01 colocalizes with α_vβ₃ integrin and VEGFR2 in treated cells.

Conclusions

Disintegrin inhibition of α_vβ₃ integrin blocks VEGFR2 signalling, even in the presence of VEGF, which impairs the angiogenic mechanism. These results improve our understanding concerning the mechanisms of pharmacological inhibition of angiogenesis.

Electronic supplementary material

The online version of this article (10.1186/s12964-019-0339-1) contains supplementary material, which is available to authorized users.

Matrix stiffness mechanically conditions EMT and migratory behavior of oral squamous cell carcinoma

Tumors are composed of heterogeneous phenotypes, each having different sensitivities to the microenvironment. One microenvironment characteristic - matrix stiffness - helps to regulate malignant transformation and invasion in mammary tumors, but its influence on oral squamous cell carcinoma (OSCC) is unclear. We observed that, on stiff matrices, a highly invasive OSCC cell line (SCC25) comprising a low E-cad to N-cad ratio (Inv^H/E:N^L; SCC25) had increased migration velocity and decreased adhesion strength compared to a less invasive OSCC cell line (Cal27) with high E-cad to N-cad ratio (Inv^L/E:N^H; Cal27). However, Inv^L/E:N^H cells acquire a mesenchymal signature and begin to migrate faster when exposed to prolonged time on a stiff niche, suggesting that cells can be mechanically conditioned. Owing to increased focal adhesion assembly, Inv^L/E:N^H cells migrated faster, which could be reduced when increasing integrin affinity with high divalent cation concentrations. Mirroring these data in human patients, we observed that collagen organization, an indicator of matrix stiffness, was increased with advanced disease and correlated with early recurrence. Consistent with epithelial tumors, our data suggest that OSCC cells are mechanically sensitive and that their contribution to tumor progression is mediated in part by this sensitivity.This article has an associated First Person interview with the first author of the paper.

Tension enhances cell proliferation and collagen synthesis by upregulating expressions of integrin αvβ3 in human keloid-derived mesenchymal stem cells

AIMS

Keloids are a dermal fibrotic disease whose etiology remains totally unknown and for which there is no successful treatment. Mechanical tension, in addition, is closely associated with the germination and development of keloids. In this study, we investigated the influence of human keloid-derived mesenchymal stem cells (KD-MSCs) on cell proliferation, collagen synthesis, and expressions of integrin αvβ3 under tension.

MAIN METHODS

KD-MSCs and human normal skin-derived mesenchymal stem cells (NS-MSCs) were isolated and cultured in stem cell medium with a gradual increase in the serum concentration. Cell proliferation and collagen synthesis were detected by Cell Counting Kit-8 (CCK-8) assay and hydroxyproline content analysis under tension respectively. We investigated the messenger RNA expressions of nine integrin subunits, including integrin units α2, α3, α5, αv, α8, α10, α11, β1, and β3, in KD-MSCs stimulated with tension. Identification of differentially expressed genes was performed by Western blot analysis and immunocytochemistry staining.

KEY FINDINGS

We obtained high-purity KD-MSCs and NS-MSCs using the culture method of decreasing serum concentration gradient gradually. Furthermore, we found that tension enhances cell proliferation and collagen synthesis and promotes expressions of integrin αvβ3 in KD-MSCs. In addition, blocking experiments showed that increased integrin αvβ3 expression affects cell proliferation and collagen synthesis of KD-MSCs under tension.

SIGNIFICANCE

Our results suggest that integrin αvβ3 receptor may be sensitive molecules of mechanical tension and could contribute to the occurrence and development of keloids. It could lead to novel targets for therapeutic intervention, treatment, and prevention of recurrence for keloid disorders.

Aberrant expression of ALDH1, MMP9, Integrin αvβ3, and KiSS-1 in invasive ductal carcinoma and their clinical significance

BACKGROUND

Aldehyde dehydrogenase 1 (ALDH1, a biomarker of cancer stem cells), matrix metalloproteinase 9 (MMP9, known as a matrilysin), Integrin αvβ3 (known as a biomarker of cell-matrix adhesion) and KiSS-1 (suppressor gene of tumor metastasis) are all related to cancer invasion and metastasis in many cancers. The purpose of this study was to investigate the expression of ALDH1, MMP9, Integrin αvβ3, and KiSS-1 in invasive ductal carcinoma (IDC), and their respective associations with clinical characteristics and survival in IDC.

METHODS

Immunohistochemical staining was used to detect the expression of ALDH1, MMP9, Integrin αvβ3, and KiSS-1 in 227 whole IDC tissue specimens. Patients' clinical and demographic data were both collected.

RESULTS

The expression of ALDH1, MMP9, and Integrin αvβ3 were significantly higher in IDC tissues than in the control tissues. The positive expressions of ALDH1, MMP9, and Integrin αvβ3 were positively associated with tumor grades, lymph node metastasis (LNM), tumor stages, and tumor node metastasis (TNM) stages, and inversely with overall survival (OS) and recurrence-free survival (RFS). Positive expression of KiSS-1 was negatively associated with tumor grades, LNM, tumor stages, and TNM stages, but positively with OS and RFS. A multivariate analysis demonstrated that the positive expression of ALDH1, MMP9, Integrin αvβ3, KiSS-1, ER, and HER-2, as well as TNM stages were independent prognostic factors for OS and RFS in IDC.

CONCLUSIONS

The expression of ALDH1, MMP9, Integrin αvβ3, and KiSS-11 should represent promising biomarkers in predicting metastasis and prognosis, as well as being potential therapeutic targets for IDC.

Alternagin-C binding to α2β1 integrin controls matrix metalloprotease-9 and matrix metalloprotease-2 in breast tumor cells and endothelial cells

Background

Matrix metalloproteinases (MMPs) are key players in tumor progression, helping tumor cells to modify their microenvironment, which allows cell migration to secondary sites. The role of integrins, adhesion receptors that connect cells to the extracellular matrix, in MMP expression and activity has been previously suggested. However, the mechanisms by which integrins control MMP expression are not completely understood. Particularly, the role of α2β1 integrin, one of the major collagen I receptors, in MMP activity and expression has not been studied. Alternagin-C (ALT-C), a glutamate-cysteine-aspartate-disintegrin from Bothrops alternatus venom, has high affinity for an α2β1 integrin. Herein, we used ALT-C as a α2β1 integrin ligand to study the effect of ALT-C on MMP-9 and MMP-2 expression as well as on tumor cells, fibroblats and endothelial cell migration.

Methods

ALT-C was purified by two steps of gel filtration followed by anion exchange chromatography. The α₂β₁ integrin binding properties of ALT-C, its dissociation constant (K_d) relative to this integrin and to collagen I (Col I) were determined by surface plasmon resonance. The effects of ALT-C (10, 40, 100 and 1000 nM) in migration assays were studied using three human cell lines: human fibroblasts, breast tumor cell line MDA-MB-231, and microvascular endothelial cells HMEC-1, considering cells found in the tumor microenvironment. ALT-C effects on MMP-9 and MMP-2 expression and activity were analyzed by quantitative PCR and gelatin zymography, respectively. Focal adhesion kinase activation was determined by western blotting.

Results

Our data demonstrate that ALT-C, after binding to α₂β₁ integrin, acts by two distinct mechanisms against tumor progression, depending on the cell type: in tumor cells, ALT-C decreases MMP-9 and MMP-2 contents and activity, but increases focal adhesion kinase phosphorylation and transmigration; and in endothelial cells, ALT-C inhibits MMP-2, which is necessary for tumor angiogenesis. ALT-C also upregulates c-Myc mRNA level, which is related to tumor suppression.

Conclusion

These results demonstrate that α₂β₁ integrin controls MMP expression and reveal this integrin as a target for the development of antiangiogenic and antimetastatic therapies.

Electronic supplementary material

The online version of this article (10.1186/s40409-018-0150-2) contains supplementary material, which is available to authorized users.

Targeting Metastasis with Snake Toxins: Molecular Mechanisms

Metastasis involves the migration of cancer cells from a primary tumor to invade and establish secondary tumors in distant organs, and it is the main cause for cancer-related deaths. Currently, the conventional cytostatic drugs target the proliferation of malignant cells, being ineffective in metastatic disease. This highlights the need to find new anti-metastatic drugs. Toxins isolated from snake venoms are a natural source of potentially useful molecular scaffolds to obtain agents with anti-migratory and anti-invasive effects in cancer cells. While there is greater evidence concerning the mechanisms of cell death induction of several snake toxin classes on cancer cells; only a reduced number of toxin classes have been reported on (i.e., disintegrins/disintegrin-like proteins, C-type lectin-like proteins, C-type lectins, serinproteases, cardiotoxins, snake venom cystatins) as inhibitors of adhesion, migration, and invasion of cancer cells. Here, we discuss the anti-metastatic mechanisms of snake toxins, distinguishing three targets, which involve (1) inhibition of extracellular matrix components-dependent adhesion and migration, (2) inhibition of epithelial-mesenchymal transition, and (3) inhibition of migration by alterations in the actin/cytoskeleton network.

High αv Integrin Level of Cancer Cells Is Associated with Development of Brain Metastasis in Athymic Rats

BACKGROUND/AIM

Brain metastases commonly occur in patients with malignant skin, lung and breast cancers resulting in high morbidity and poor prognosis. Integrins containing an αv subunit are cell adhesion proteins that contribute to cancer cell migration and cancer progression. We hypothesized that high expression of αv integrin cell adhesion protein promoted metastatic phenotypes in cancer cells.

MATERIALS AND METHODS

Cancer cells from different origins were used and studied regarding their metastatic ability and intetumumab, anti-αv integrin mAb, sensitivity using in vitro cell migration assay and in vivo brain metastases animal models.

RESULTS

The number of brain metastases and the rate of occurrence were positively correlated with cancer cell αv integrin levels. High αv integrin-expressing cancer cells showed significantly faster cell migration rate in vitro than low αv integrin-expressing cells. Intetumumab significantly inhibited cancer cell migration in vitro regardless of αv integrin expression level. Overexpression of αv integrin in cancer cells with low αv integrin level accelerated cell migration in vitro and increased the occurrence of brain metastases in vivo.

CONCLUSION

αv integrin promotes brain metastases in cancer cells and may mediate early steps in the metastatic cascade, such as adhesion to brain vasculature. Targeting αv integrin with intetumumab could provide clinical benefit in treating cancer patients who develop metastases.