PAK6 acts downstream of IQGAP3 to promote contractility in triple negative breast cancer cells

Breast cancer is a heterogeneous disease that remains the most common malignancy among women worldwide. During genomic analysis of breast tumours, mRNA levels of IQGAP3 were found to be upregulated in triple negative tumours. IQGAP3 was subsequently found to be expressed across a panel of triple negative breast cancer (TNBC) cell lines. Depleting expression levels of IQGAP3 delivered elongated cells, disrupted cell migration, and inhibited the ability of cells to form specialised invasive adhesion structures, termed invadopodia. The morphological changes induced by IQGAP3 depletion were found to be dependent on RhoA. Indeed, reduced expression of IQGAP3 disrupted RhoA activity and actomyosin contractility. Interestingly, IQGAP3 was also found to interact with p-21 activated kinase 6 (PAK6); a protein already associated with the regulation of cell morphology. Moreover, PAK6 depletion phenocopied IQGAP3 depletion in these cells. Whereas PAK6 overexpression rescued the IQGAP3 depletion phenotype. Our work points to an important PAK6-IQGAP3-RhoA pathway that drives the cellular contractility of breast cancer cells promoting both cell migration and adhesive invasion of these cells. As this phenotype is relevant to the process of metastasis and re-seeding of metastasis, the pharmacological targeting of PAK6 could lead to clinical benefit in TNBC patients.

MCT4 and CD147 colocalize with MMP14 in invadopodia and support matrix degradation and invasion by breast cancer cells

Expression levels of the lactate-H+ cotransporter MCT4 (also known as SLC16A3) and its chaperone CD147 (also known as basigin) are upregulated in breast cancers, correlating with decreased patient survival. Here, we test the hypothesis that MCT4 and CD147 favor breast cancer invasion through interdependent effects on extracellular matrix (ECM) degradation. MCT4 and CD147 expression and membrane localization were found to be strongly reciprocally interdependent in MDA-MB-231 breast cancer cells. Overexpression of MCT4 and/or CD147 increased, and their knockdown decreased, migration, invasion and the degradation of fluorescently labeled gelatin. Overexpression of both proteins led to increases in gelatin degradation and appearance of the matrix metalloproteinase (MMP)-generated collagen-I cleavage product reC1M, and these increases were greater than those observed upon overexpression of each protein alone, suggesting a concerted role in ECM degradation. MCT4 and CD147 colocalized with invadopodia markers at the plasma membrane. They also colocalized with MMP14 and the lysosomal marker LAMP1, as well as partially with the autophagosome marker LC3, in F-actin-decorated intracellular vesicles. We conclude that MCT4 and CD147 reciprocally regulate each other and interdependently support migration and invasiveness of MDA-MB-231 breast cancer cells. Mechanistically, this involves MCT4-CD147-dependent stimulation of ECM degradation and specifically of MMP-mediated collagen-I degradation. We suggest that the MCT4-CD147 complex is co-delivered to invadopodia with MMP14.

Nuclear transport of phosphorylated LanCL2 promotes invadopodia formation and tumor progression of glioblastoma by activating STAT3/Cortactin signaling

INTRODUCTION

Our previous study showed that the abscisic acid receptor lanthionine synthetase C-like 2 (LanCL2) is a significant prognostic factor for overall survival in young glioblastoma patients. However, the role of LanCL2 in glioblastoma remains unclear yet.

OBJECTIVES

This study aims to investigate the role of LanCL2 in regulating in-vitro cell invasion and in-vivo tumor progression of glioblastoma and its underlying mechanism.

METHODS

Tyrosine 198 or 295 residue of LanCL2 was mutated using site-directed mutagenesis to block its phosphorylation. The role of LanCL2 in glioblastoma was investigated using transwell or 3D invasion assay, matrix degradation assay and intracranial xenograft model.

RESULTS

This study showed that nuclear transport of LanCL2 was enhanced by overexpression of LanCL2 or its ligand abscisic acid in glioblastoma cells. Knockdown of LanCL2 suppressed migration, invasion and invadopodia formation of glioblastoma cells, whereas overexpression of wild-type LanCL2 enhanced them. Blocking of Tyr295 residue phosphorylation of LanCL2 impeded its nuclear transport, retarded glioblastoma cell motility and invadopodia formation, and deceased the phosphorylation of Cortactin and STAT3. c-Met was identified as the upstream tyrosine kinase of Tyr295 residue of LanCL2, and inhibition of c-Met markedly suppressed the nuclear transport of LanCL2. Moreover, overexpression of wild-type LanCL2 significantly promoted orthotopic tumor growth of glioblastoma in vivo and led to poor survival of mice with median survival time of 33.5 days, whereas Tyr295 mutation rescued it with median survival time of 49 days.

CONCLUSION

Our findings suggested that Tyr295 phosphorylation is crucial to the activation and nuclear transport of LanCL2, as well as invadopodia formation and tumor progression of glioblastoma, providing the evidence of a novel signaling axis c-Met/LanCL2/STAT3/Cortactin and the first observation of the importance of Tyr295 phosphorylation to LanCL2.

The C. elegans anchor cell: A model to elucidate mechanisms underlying invasion through basement membrane

Cell invasion through basement membrane barriers is crucial during many developmental processes and in immune surveillance. Dysregulation of invasion also drives the pathology of numerous human diseases, such as metastasis and inflammatory disorders. Cell invasion involves dynamic interactions between the invading cell, basement membrane, and neighboring tissues. Owing to this complexity, cell invasion is challenging to study in vivo, which has hampered the understanding of mechanisms controlling invasion. Caenorhabditis elegans anchor cell invasion is a powerful in vivo model where subcellular imaging of cell-basement membrane interactions can be combined with genetic, genomic, and single-cell molecular perturbation studies. In this review, we outline insights gained by studying anchor cell invasion, which span transcriptional networks, translational regulation, secretory apparatus expansion, dynamic and adaptable protrusions that breach and clear basement membrane, and a complex, localized metabolic network that fuels invasion. Together, investigation of anchor cell invasion is building a comprehensive understanding of the mechanisms that underlie invasion, which we expect will ultimately facilitate better therapeutic strategies to control cell invasive activity in human disease.

A synergistic regulation works in matrix stiffness-driven invadopodia formation in HCC

Growing evidence has suggested that increased matrix stiffness can significantly strengthen the malignant characteristics of hepatocellular carcinoma (HCC) cells. However, whether and how increased matrix stiffness regulates the formation of invadopodia in HCC cells remain largely unknown. In the study, we developed different experimental systems in vitro and in vivo to explore the effects of matrix stiffness on the formation of invadopodia and its relevant molecular mechanism. Our results demonstrated that increased matrix stiffness remarkably augmented the migration and invasion abilities of HCC cells, upregulated the expressions of invadopodia-associated genes and enhanced the number of invadopodia. Two regulatory pathways contribute to matrix stiffness-driven invadopodia formation together in HCC cells, including direct triggering invadopodia formation through activating integrin β1 or Piezo1/ FAK/Src/Arg/cortactin pathway, and indirect stimulating invadopodia formation through improving EGF production to activate EGFR/Src/Arg/cortactin pathway. Src was identified as the common hub molecule of two synergistic regulatory pathways. Simultaneously, activation of integrin β1/RhoA/ROCK1/MLC2 and Piezo1/Ca2+/MLCK/MLC2 pathways mediate matrix stiffness-reinforced cell migration. This study uncovers a new mechanism by which mechanosensory pathway and biochemical signal pathway synergistically regulate the formation of invadopodia in HCC cells.

Assessment of Invadopodium Formation and Gelatin Degradation in Vitro

Some cancer cells form highly regulated structures, termed invadopodia, which mediate local, enzymatic degradation of extracellular matrix and facilitate cancer cell invasion and migration during metastatic progression. Understanding invadopodium formation and function in cancer cells is therefore an important strategy to find novel clinical approaches to interfere with metastasis. Invadopodia are F-actin-rich protrusions that form on the advancing edge of cells, supported by complex molecular interactions at the cell membrane. Invadopodia formation, structure, and function can be studied in vitro, using commonly cultured cancer cell lines and standard microscopic techniques. Here, these approaches are described in detail.

Invadopodia associated Thrombospondin-1 contributes to a post-therapy pro-invasive response in glioblastoma cells

A critical challenge in the treatment of glioblastoma (GBM) is its highly invasive nature which promotes cell migration throughout the brain and hinders surgical resection and effective drug delivery. GBM cells demonstrate augmented invasive capabilities following exposure to the current gold standard treatment of radiotherapy (RT) and concomitant and adjuvant temozolomide (TMZ), resulting in rapid disease recurrence. Elucidating the mechanisms employed by post-treatment invasive GBM cells is critical to the development of more effective therapies. In this study, we utilized a Nanostring® Cancer Progression gene expression panel to identify candidate genes that may be involved in enhanced GBM cell invasion after treatment with clinically relevant doses of RT/TMZ. Our findings identified thrombospondin-1 (THBS1) as a pro-invasive gene that is upregulated in these cells. Immunofluorescence staining revealed that THBS1 localised within functional matrix-degrading invadopodia that formed on the surface of GBM cells. Furthermore, overexpression of THBS1 resulted in enhanced GBM cell migration and secretion of MMP-2, which was reduced with silencing of THBS1. The preliminary data demonstrates that THBS1 is associated with invadopodia in GBM cells and is likely involved in the invadopodia-mediated invasive process in GBM cells exposed to RT/TMZ treatment. Therapeutic inhibition of THBS1-mediated invadopodia activity, which facilitates GBM cell invasion, should be further investigated as a treatment for GBM.

Loss of ORP3 induces aneuploidy and promotes bladder cancer cell invasion through deregulated microtubule and actin dynamics

We have recently shown that loss of ORP3 leads to aneuploidy induction and promotes tumor formation. However, the specific mechanisms by which ORP3 contributes to ploidy-control and cancer initiation and progression is still unknown. Here, we report that ORP3 is highly expressed in ureter and bladder epithelium while its expression is downregulated in invasive bladder cancer cell lines and during tumor progression, both in human and in mouse bladder cancer. Moreover, we observed an increase in the incidence of N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN)-induced invasive bladder carcinoma in the tissue-specific Orp3 knockout mice. Experimental data demonstrate that ORP3 protein interacts with γ-tubulin at the centrosomes and with components of actin cytoskeleton. Altering the expression of ORP3 induces aneuploidy and genomic instability in telomerase-immortalized urothelial cells with a stable karyotype and influences the migration and invasive capacity of bladder cancer cell lines. These findings demonstrate a crucial role of ORP3 in ploidy-control and indicate that ORP3 is a bona fide tumor suppressor protein. Of note, the presented data indicate that ORP3 affects both cell invasion and migration as well as genome stability through interactions with cytoskeletal components, providing a molecular link between aneuploidy and cell invasion and migration, two crucial characteristics of metastatic cells.

Isotoosendanin exerts inhibition on triple-negative breast cancer through abrogating TGF-β-induced epithelial-mesenchymal transition via directly targeting TGFβR1

As the most aggressive breast cancer, triple-negative breast cancer (TNBC) is still incurable and very prone to metastasis. The transform growth factor β (TGF-β)-induced epithelial-mesenchymal transition (EMT) is crucially involved in the growth and metastasis of TNBC. This study reported that a natural compound isotoosendanin (ITSN) reduced TNBC metastasis by inhibiting TGF-β-induced EMT and the formation of invadopodia. ITSN can directly interact with TGF-β receptor type-1 (TGFβR1) and abrogated the kinase activity of TGFβR1, thereby blocking the TGF-β-initiated downstream signaling pathway. Moreover, the ITSN-provided inhibition on metastasis obviously disappeared in TGFβR1-overexpressed TNBC cells in vitro as well as in mice bearing TNBC cells overexpressed TGFβR1. Furthermore, Lys232 and Asp351 residues in the kinase domain of TGFβR1 were found to be crucial for the interaction of ITSN with TGFβR1. Additionally, ITSN also improved the inhibitory efficacy of programmed cell death 1 ligand 1 (PD-L1) antibody for TNBC in vivo via inhibiting the TGF-β-mediated EMT in the tumor microenvironment. Our findings not only highlight the key role of TGFβR1 in TNBC metastasis, but also provide a leading compound targeting TGFβR1 for the treatment of TNBC metastasis. Moreover, this study also points out a potential strategy for TNBC treatment by using the combined application of anti-PD-L1 with a TGFβR1 inhibitor.

Repurposing FDA-approved drugs as inhibitors of therapy-induced invadopodia activity in glioblastoma cells

Glioblastoma (GBM) is the most prevalent primary central nervous system tumour in adults. The lethality of GBM lies in its highly invasive, infiltrative, and neurologically destructive nature resulting in treatment failure, tumour recurrence and death. Even with current standard of care treatment with surgery, radiotherapy and chemotherapy, surviving tumour cells invade throughout the brain. We have previously shown that this invasive phenotype is facilitated by actin-rich, membrane-based structures known as invadopodia. The formation and matrix degrading activity of invadopodia is enhanced in GBM cells that survive treatment. Drug repurposing provides a means of identifying new therapeutic applications for existing drugs without the need for discovery or development and the associated time for clinical implementation. We investigate several FDA-approved agents for their ability to act as both cytotoxic agents in reducing cell viability and as 'anti-invadopodia' agents in GBM cell lines. Based on their cytotoxicity profile, three agents were selected, bortezomib, everolimus and fludarabine, to test their effect on GBM cell invasion. All three drugs reduced radiation/temozolomide-induced invadopodia activity, in addition to reducing GBM cell viability. These drugs demonstrate efficacious properties warranting further investigation with the potential to be implemented as part of the treatment regime for GBM.

Small extracellular vesicles promote invadopodia activity in glioblastoma cells in a therapy-dependent manner

PURPOSE

The therapeutic efficacy of radiotherapy/temozolomide treatment for glioblastoma (GBM) is limited by the augmented invasiveness mediated by invadopodia activity of surviving GBM cells. As yet, however the underlying mechanisms remain poorly understood. Due to their ability to transport oncogenic material between cells, small extracellular vesicles (sEVs) have emerged as key mediators of tumour progression. We hypothesize that the sustained growth and invasion of cancer cells depends on bidirectional sEV-mediated cell-cell communication.

METHODS

Invadopodia assays and zymography gels were used to examine the invadopodia activity capacity of GBM cells. Differential ultracentrifugation was utilized to isolate sEVs from conditioned medium and proteomic analyses were conducted on both GBM cell lines and their sEVs to determine the cargo present within the sEVs. In addition, the impact of radiotherapy and temozolomide treatment of GBM cells was studied.

RESULTS

We found that GBM cells form active invadopodia and secrete sEVs containing the matrix metalloproteinase MMP-2. Subsequent proteomic studies revealed the presence of an invadopodia-related protein sEV cargo and that sEVs from highly invadopodia active GBM cells (LN229) increase invadopodia activity in sEV recipient GBM cells. We also found that GBM cells displayed increases in invadopodia activity and sEV secretion post radiation/temozolomide treatment. Together, these data reveal a relationship between invadopodia and sEV composition/secretion/uptake in promoting the invasiveness of GBM cells.

CONCLUSIONS

Our data indicate that sEVs secreted by GBM cells can facilitate tumour invasion by promoting invadopodia activity in recipient cells, which may be enhanced by treatment with radio-chemotherapy. The transfer of pro-invasive cargos may yield important insights into the functional capacity of sEVs in invadopodia.

Invadopodia Methods: Detection of Invadopodia Formation and Activity in Cancer Cells Using Reconstituted 2D and 3D Collagen-Based Matrices

Tumor dissemination involves cancer cell migration through the extracellular matrix (ECM). ECM is mainly composed of collagen fibers that oppose cell invasion. To overcome hindrance in the matrix, cancer cells deploy a protease-dependent program in order to remodel the matrix fibers. Matrix remodeling requires the formation of actin-based matrix/plasma membrane contact sites called invadopodia, responsible for collagen cleavage through the accumulation and activity of the transmembrane type-I matrix metalloproteinase (MT1-MMP). In this article, we describe experimental procedures designed to assay for invadopodia formation and for invadopodia activity using 2D and 3D models based on gelatin (denatured collagen) and fibrillar type-I collagen matrices.

Quantification of Invadopodia Formation and Matrix Degradation Activity

Cancer cells possess a remarkable capacity to dissociate from a primary tumor, invade the surrounding tissues and vasculature, and eventually form metastases in distant organs. This complex and multistep process remains one of the major causes of mortality in cancer patients worldwide. Multiple studies have highlighted the role of actin-rich structures called invadopodia ("invasive feet"), which adhere to the matrix, contain and secrete matrix-degrading proteinases, and apply protrusive forces generated by the actin cytoskeleton, which drive the invasive process. Here, we describe a fluorescent microscopy-based protocol for imaging and quantifying both invadopodia formation and matrix degradation.

BTB domain and CNC homolog 1 promotes glioma invasion mainly through regulating extracellular matrix and increases ferroptosis sensitivity

BTB Domain and CNC Homolog 1 (Bach1) has been implicated in cancer progression, particularly in invasion, but little is unknown about its effect on glioma. Here, we confirmed that highly expressed Bach1 prominently promoted glioma invasion. Similar to the reported mechanisms in other tumors, Bach1 upregulation was also correlated with epithelial mesenchymal transition (EMT) in glioma cells. More importantly, proteomic analysis indicated that the main mechanism of Bach1 promoting invasion in glioma involved extracellular matrix (ECM). We further found thatBach1 upregulation was associated with the multiple mechanisms of ECM remodeling in glioma, including increasing the expression and deposition of ECM components, activating TGFBR2-smad2/3 signaling, promoting invadopodia formation and inducing the expression and secretion of MMP2. Meanwhile, Bach1 overexpression increased ferroptosis sensitivity in glioma cells. The ferroptosis inducer (sulfasalazine) obviously suppressed the gliomas with Bach1 upregulation in vitro and in vivo. Overall, Bach1 has a two-faced role in glioma. Highly expressed Bach1 promotes glioma invasion. Conversely, Bach1 upregulation is also a potential indicator of the sensitivity of ferroptosis inducers.

Evaluation of the matrix metalloproteinase 9 (MMP9) inhibitor Andecaliximab as an Anti-invasive therapeutic in Head and neck squamous cell carcinoma

OBJECTIVES

Locoregional and lymphovascular involvement of invasive head and neck squamous cell carcinoma (HNSCC) complicates curative treatment. Matrix metalloproteinase (MMP) 9 is a negative prognostic marker in HNSCC and targets multiple extracellular matrix (ECM) substrates, where it contributes to breaching basement membrane and stromal barriers enabling invasive spread. Andecaliximab (ADX) is a second-generation MMP9 inhibitor well tolerated in clinical trials of gastric and pancreatic adenocarcinoma. The impact of selective MMP9 targeting by ADX in HNSCC has not been evaluated.

MATERIALS AND METHODS

Established and patient-derived xenograft (PDX) cell lines were utilized in HNSCC invasion assays to determine the inhibitory ability of MMP9-mediated invasion by ADX. MMP9 expression was confirmed using immunohistochemistry (IHC) and immunoblotting. ECM degradation was evaluated with confocal microscopy. Cell invasion from tumor spheroids was monitored by phase microscopy. Histological evaluation was used to determine ADX efficacy in three-dimensional organotypic cultures containing cancer associated fibroblasts (CAFs).

RESULTS

MMP9 was expressed in all established and PDX-derived cell lines. While the broad spectrum clinical MMP inhibitor marimastat (BB2516) blocked HNSCC invadopodia function and tumor spheroid invasion, ADX treatment failed to inhibit invadopodia-based matrix degradation, tumor cell or fibroblast-driven ECM invasion in collagen I-based matrices.

CONCLUSION

ADX monotherapy was ineffective at blocking initial MMP-dependent events of HNSCC invasion, likely due to redundant functions of additional non-targeted MMPs produced by tumor cells and microenvironment. Combination of ADX with existing and emerging therapies targeting additional MMP activation pathways may warrant future investigation.

Syntaxin 7 contributes to breast cancer cell invasion by promoting invadopodia formation

Invasion in various cancer cells requires coordinated delivery of signaling proteins, adhesion proteins, actin-remodeling proteins and proteases to matrix-degrading structures called invadopodia. Vesicular trafficking involving SNAREs plays a crucial role in the delivery of cargo to the target membrane. Screening of 13 SNAREs from the endocytic and recycling route using a gene silencing approach coupled with functional assays identified syntaxin 7 (STX7) as an important player in MDA-MB-231 cell invasion. Total internal reflection fluorescence microscopy (TIRF-M) studies revealed that STX7 resides near invadopodia and co-traffics with MT1-MMP (also known as MMP14), indicating a possible role for this SNARE in protease trafficking. STX7 depletion reduced the number of invadopodia and their associated degradative activity. Immunoprecipitation studies revealed that STX7 forms distinct SNARE complexes with VAMP2, VAMP3, VAMP7, STX4 and SNAP23. Depletion of VAMP2, VAMP3 or STX4 abrogated invadopodia formation, phenocopying what was seen upon lack of STX7. Whereas depletion of STX4 reduced MT1-MMP level at the cell surfaces, STX7 silencing significantly reduced the invadopodia-associated MT1-MMP pool and increased the non-invadosomal pool. This study highlights STX7 as a major contributor towards the invadopodia formation during cancer cell invasion. This article has an associated First Person interview with the first author of the paper.

PLXDC2 enhances invadopodium formation to promote invasion and metastasis of gastric cancer cells via interacting with PTP1B

Plexin-domain containing 2 (PLXDC2) has been reported as an oncoprotein in several human malignancies. However, its expression and roles in gastric cancer remain largely unclear. In this study, we found that PLXDC2 was highly expressed in gastric cancer tissues, and the expression levels were positively correlated with clinicopathological features, but negatively with the patients’ outcome. Cox regression analysis identified PLXDC2 as an independent prognostic indicator for the patients. Knockdown of PLXDC2 markedly suppressed the in vitro invasion and in vivo metastasis of gastric cancer cells, while overexpression of PLXDC2 resulted in opposite effects. Mechanistically, PLXDC2 enhanced the level of phosphorylated Cortactin (p-Cortactin) by physically interacting with protein tyrosine phosphatase 1B (PTP1B), an important dephosphorylase, to prevent its dephosphorylating of p-Cortactin, thereby promoting the formation of invadopodia. Collectively, our results indicate that PLXDC2 contributes to the invasion and metastasis of gastric cancer by inhibiting PTP1B to facilitate the invadopodium formation, and may serve as a potential prognostic biomarker and a therapeutic target for this disease.

StarD13 negatively regulates invadopodia formation and invasion in high-grade serous (HGS) ovarian adenocarcinoma cells by inhibiting Cdc42

Metastasis remains the main challenge to overcome for treating ovarian cancers. In this study, we investigate the potential role of the Cdc42 GAP StarD13 in the modulation of cell motility, invasion in ovarian cancer cells. StarD13 depletion does not affect the 2D motility of ovarian cancer cells. More importantly, StarD13 inhibits matrix degradation, invadopodia formation and cell invasion through the inhibition of Cdc42. StarD13 does not localize to mature TKS4-labeled invadopodia that possess matrix degradation ability, while a Cdc42 FRET biosensor, detects Cdc42 activation in these invadopodia. In fact, StarD13 localization and Cdc42 activation appear mutually exclusive in invadopodial structures. Finally, for the first time we uncover a potential role of Cdc42 in the direct recruitment of TKS4 to invadopodia. This study emphasizes the specific role of StarD13 as a narrow spatial regulator of Cdc42, inhibiting invasion, suggesting the suitability of StarD13 for targeted therapy.

Data on the effects of ECM rigidity on actomyosin contractility and invadopodia activity in individual versus pairs of head and neck squamous cell carcinoma cells

Migration through the extracellular matrix (ECM) is essential for cancer cells to escape the primary tumor and invade neighboring tissues with the potential for metastasis [1]. To penetrate tissue barriers, migrating cancer cells degrade the ECM with actin-rich membrane protrusions called invadopodia [2]. We have previously found that invadopodial ECM degradation is regulated by ECM rigidity in a process mediated by contractile forces in individual head and neck squamous cell carcinoma (HNSCC) cells [3], [4]. However, cancer cells often migrate together and interact with each other to alter their actomyosin contractility in response to the biomechanical properties of the ECM [5]. Therefore, we tested whether ECM rigidity promotes biomechanical interactions between cancer cells to enhance proteolytic activity. Using a minimal model of two HNSCC cells in physical contact, we provide data here that actomyosin contractility, invadopodia formation, and ECM degradation increase in response to ECM rigidity when cells are in pairs versus individual cells using traction force and invadopodia assays.

LINC00511 drives invasive behavior in hepatocellular carcinoma by regulating exosome secretion and invadopodia formation

Background

Tumor cells are known to release large numbers of exosomes containing active substances that participate in cancer progression. Abnormally expressed long noncoding RNAs (lncRNAs) have been confirmed to regulate multiple processes associated with tumor progression. However, the mechanism by which lncRNAs affect exosome secretion remains unclear.

Methods

The underlying mechanisms of long noncoding RNA LINC00511 (LINC00511) regulation of multivesicular body (MVB) trafficking, exosome secretion, invadopodia formation, and tumor invasion were determined through gene set enrichment analysis (GSEA), immunoblotting, nanoparticle tracking analysis, confocal colocalization analysis, electron microscopy, and invasion experiments.

Results

We revealed that the tumorigenesis process is associated with a significant increase in vesicle secretion in hepatocellular carcinoma (HCC). Additionally, LINC00511 was significantly more highly expressed in HCC tissues and is related to vesicle trafficking and MVB distribution. We also found that in addition to the formation of invadopodia in HCC progression, abnormal LINC00511 induces invadopodia formation in HCC cells by regulating the colocalization of vesicle associated membrane protein 7 (VAMP7) and synaptosome associated protein 23 (SNAP23) to induce the invadopodia formation, which are key secretion sites for MVBs and control exosome secretion. Finally, we revealed that LINC0051-induced invadopodia and exosome secretion were involved in tumor progression.

Conclusions

Our experiments revealed novel findings on the relationship between LINC00511 dysregulation in HCC and invadopodia production and exosome secretion. This is a novel mechanism by which LINC00511 regulates invadopodia biogenesis and exosome secretion to further promote cancer progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01990-y.

The phosphatase Shp1 interacts with and dephosphorylates cortactin to inhibit invadopodia function

BACKGROUND

Invadopodia are actin-based cell-membrane protrusions associated with the extracellular matrix degradation accompanying cancer invasion. The elucidation of the molecular mechanisms leading to invadopodia formation and activity is central for the prevention of tumor spreading and growth. Protein tyrosine kinases such as Src are known to regulate invadopodia assembly, little is however known on the role of protein tyrosine phosphatases in this process. Among these enzymes, we have selected the tyrosine phosphatase Shp1 to investigate its potential role in invadopodia assembly, due to its involvement in cancer development.

METHODS

Co-immunoprecipitation and immunofluorescence studies were employed to identify novel substrate/s of Shp1AQ controlling invadopodia activity. The phosphorylation level of cortactin, the Shp1 substrate identified in this study, was assessed by immunoprecipitation, in vitro phosphatase and western blot assays. Short interference RNA and a catalytically-dead mutant of Shp1 expressed in A375MM melanoma cells were used to evaluate the role of the specific Shp1-mediated dephosphorylation of cortactin. The anti-invasive proprieties of glycerophosphoinositol, that directly binds and regulates Shp1, were investigated by extracellular matrix degradation assays and in vivo mouse model of metastasis.

RESULTS

The data show that Shp1 was recruited to invadopodia and promoted the dephosphorylation of cortactin at tyrosine 421, leading to an attenuated capacity of melanoma cancer cells to degrade the extracellular matrix. Controls included the use of short interference RNA and catalytically-dead mutant that prevented the dephosphorylation of cortactin and hence the decrease the extracellular matrix degradation by melanoma cells. In addition, the phosphoinositide metabolite glycerophosphoinositol facilitated the localization of Shp1 at invadopodia hence promoting cortactin dephosphorylation. This impaired invadopodia function and tumor dissemination both in vitro and in an in vivo model of melanomas.

CONCLUSION

The main finding here reported is that cortactin is a specific substrate of the tyrosine phosphatase Shp1 and that its phosphorylation/dephosphorylation affects invadopodia formation and, as a consequence, the ability of melanoma cells to invade the extracellular matrix. Shp1 can thus be considered as a regulator of melanoma cell invasiveness and a potential target for antimetastatic drugs. Video abstract.

Focal adhesion dynamics in cellular function and disease

Acting as a bridge between the cytoskeleton of the cell and the extra cellular matrix (ECM), the cell-ECM adhesions with integrins at their core, play a major role in cell signalling to direct mechanotransduction, cell migration, cell cycle progression, proliferation, differentiation, growth and repair. Biochemically, these adhesions are composed of diverse, yet an organised group of structural proteins, receptors, adaptors, various enzymes including protein kinases, phosphatases, GTPases, proteases, etc. as well as scaffolding molecules. The major integrin adhesion complexes (IACs) characterised are focal adhesions (FAs), invadosomes (podosomes and invadopodia), hemidesmosomes (HDs) and reticular adhesions (RAs). The varied composition and regulation of the IACs and their signalling, apart from being an integral part of normal cell survival, has been shown to be of paramount importance in various developmental and pathological processes. This review per-illustrates the recent advancements in the research of IACs, their crucial roles in normal as well as diseased states. We have also touched on few of the various methods that have been developed over the years to visualise IACs, measure the forces they exert and study their signalling and molecular composition. Having such pertinent roles in the context of various pathologies, these IACs need to be understood and studied to develop therapeutical targets. We have given an update to the studies done in recent years and described various techniques which have been applied to study these structures, thereby, providing context in furthering research with respect to IAC targeted therapeutics.

Hyaluronan synthase 2 (HAS2) regulates cell phenotype and invadopodia formation in luminal-like breast cancer cells

Although luminal breast cancer cells are typically highly cohesive epithelial cells and have low invasive ability, many eventually develop metastasis. Until now, the underlying mechanisms remain obscure. In this work, we showed that the level of hyaluronic acid synthase 2 (HAS2) was positively correlated with the malignant phenotype of breast cancer cells. Notably, the increased expression of HAS2 promoted the invasive and migratory abilities of luminal breast cancer cells in vitro, followed by a reduced expression of E-cadherin, β-catenin, and ZO-1, and an elevated expression of N-cadherin and vimentin. Furthermore, overexpression of HAS2 promoted while knockdown of HAS2 impeded invadopodia formation, which subsequently increased or decreased the activation of cortactin, Tks5, and metalloproteinases (MMPs). Activation of these invadopodia-related proteins was prevented by inhibition of HAS2 or disruption of HA, which in turn attenuated the increased motility and invasiveness. Further, in vivo study showed that, HAS2 increased tumor growth and the rate of lung metastasis via driving transition to an invasive cell phenotype in SCID mice that were orthotopically transplanted with luminal breast cancer cells. Collectively, our results showed that HAS2 promoted cell invasion by inducing transition to an invasive phenotype and by enhancing invadopodia formation in luminal breast cancer cells, which may provide new mechanistic insights into its role in tumor metastasis.

Key proteins of invadopodia are overexpressed in oral squamous cell carcinoma suggesting an important role of MT1-MMP in the tumoral progression

BACKGROUND

Oral squamous cell carcinoma (OSCC) is the most relevant malignant neoplasm among all head and neck tumours due to its high prevalence and unfavourable prognosis. Tumour invasion and metastasis that affect prognosis are result of a set of complex events that cells with invasive potential use to spread to other regions. These cells use several mechanisms to invade tissues, including a type of finger-like membrane protrusion called invadopodia. This study aims to investigate the immunoexpression of invaopodia related-proteins TKs5, cortactin, TKs4 and MT1-MMP in OSCC and correlate it to clinicopathological data.

METHODS

An immunohistochemical evaluation of fifty cases of OSCCs and 20 cases of oral mucosa (OM) were assessed. The expression of invadopodia proteins were analysed in comparison to normal tissue (OM) and correlated to different clinical-stage and histological grade of OSCC.

RESULTS

TKs5, cortactin, TKs4 and MT1-MMP were significantly overexpressed in OSCC when compared to OM (p < 0.0001). Among tumour stages, TKs5 showed a statistical difference in immunolabelling between stage I and III (p = 0.026). Cortactin immunolabelling was statistically higher in grade I than in grade II and III. No differences were seen on TKs4 expression based on tumour staging or grading. MT1-MMP was higher expressed and showed statistical difference between stages I and III and grades I compared to II and III.

CONCLUSIONS

The invadopodia related-proteins were found to be overexpressed in OSCC when compared to OM, suggesting invadopodia formation and activity. Besides overexpressed in OSCC, cortactin, TKs4 and TKs5 showed no or ambiguous differences in protein expression when compared among clinical-stages or histological grades groups. Conversely, the expression of MT1-MMP increased in advanced stages and less differentiated tumours, suggesting MT1-MMP expression as a promising prognostic marker in OSCC.

The multiple roles of actin-binding proteins at invadopodia

Invadopodia are actin-rich membrane protrusions that facilitate cancer cell dissemination by focusing on proteolytic activity and clearing paths for migration through physical barriers, such as basement membranes, dense extracellular matrices, and endothelial cell junctions. Invadopodium formation and activity require spatially and temporally regulated changes in actin filament organization and dynamics. About three decades of research have led to a remarkable understanding of how these changes are orchestrated by sequential recruitment and coordinated activity of different sets of actin-binding proteins. In this chapter, we provide an update on the roles of the actin cytoskeleton during the main stages of invadopodium development with a particular focus on actin polymerization machineries and production of pushing forces driving extracellular matrix remodeling.

Inhibition of β1 integrin induces its association with MT1-MMP and decreases MT1-MMP internalization and cellular invasiveness

Integrin signaling plays a fundamental role in the establishment of focal adhesions and the subsequent formation of invadopodia in malignant cancer cells. Invadopodia facilitate localized adhesion and degradation of the extracellular matrix (ECM), which promote tumour cell invasion and metastasis. Degradation of ECM components is often driven by membrane type-1 matrix metalloproteinase (MT1-MMP), and we have recently shown that regulation of enzyme internalization is dependent on signaling downstream of β1 integrin. Phosphorylation of the cytoplasmic tail of MT1-MMP is required for its internalization and delivery to Rab5-marked early endosomes, where it is then able to be recycled to new sites of invadopodia formation and promote invasion. Here we found that inhibition of β1 integrin, using the antibody AIIB2, inhibited the internalization and recycling of MT1-MMP that is necessary to support long-term cellular invasion. MT1-MMP and β1 integrin were sequestered at the cell surface when β1-integrin was inhibited, and their association under these conditions was detected using immunoprecipitation and mass spectrometry analyses. Sequestration of β1 integrin and MT1-MMP at the cell surface resulted in the formation of large invadopodia and local ECM degradation; however, the impaired internalization and recycling of MT1-MMP and β1 integrin ultimately led to a loss of invasive behaviour.

L-plastin Ser5 phosphorylation is modulated by the PI3K/SGK pathway and promotes breast cancer cell invasiveness

Background

Metastasis is the predominant cause for cancer morbidity and mortality accounting for approximatively 90% of cancer deaths. The actin-bundling protein L-plastin has been proposed as a metastatic marker and phosphorylation on its residue Ser5 is known to increase its actin-bundling activity. We recently showed that activation of the ERK/MAPK signalling pathway leads to L-plastin Ser5 phosphorylation and that the downstream kinases RSK1 and RSK2 are able to directly phosphorylate Ser5. Here we investigate the involvement of the PI3K pathway in L-plastin Ser5 phosphorylation and the functional effect of this phosphorylation event in breast cancer cells.

Methods

To unravel the signal transduction network upstream of L-plastin Ser5 phosphorylation, we performed computational modelling based on immunoblot analysis data, followed by experimental validation through inhibition/overexpression studies and in vitro kinase assays. To assess the functional impact of L-plastin expression/Ser5 phosphorylation in breast cancer cells, we either silenced L-plastin in cell lines initially expressing endogenous L-plastin or neoexpressed L-plastin wild type and phosphovariants in cell lines devoid of endogenous L-plastin. The established cell lines were used for cell biology experiments and confocal microscopy analysis.

Results

Our modelling approach revealed that, in addition to the ERK/MAPK pathway and depending on the cellular context, the PI3K pathway contributes to L-plastin Ser5 phosphorylation through its downstream kinase SGK3. The results of the transwell invasion/migration assays showed that shRNA-mediated knockdown of L-plastin in BT-20 or HCC38 cells significantly reduced cell invasion, whereas stable expression of the phosphomimetic L-plastin Ser5Glu variant led to increased migration and invasion of BT-549 and MDA-MB-231 cells. Finally, confocal image analysis combined with zymography experiments and gelatin degradation assays provided evidence that L-plastin Ser5 phosphorylation promotes L-plastin recruitment to invadopodia, MMP-9 activity and concomitant extracellular matrix degradation.

Conclusion

Altogether, our results demonstrate that L-plastin Ser5 phosphorylation increases breast cancer cell invasiveness. Being a downstream molecule of both ERK/MAPK and PI3K/SGK pathways, L-plastin is proposed here as a potential target for therapeutic approaches that are aimed at blocking dysregulated signalling outcome of both pathways and, thus, at impairing cancer cell invasion and metastasis formation.

Invadopodia: A potential target for pancreatic cancer therapy

Dissemination of cancer cells is an intricate multistep process that represents the most deadly aspect of cancer. Cancer cells form F-actin-rich protrusions known as invadopodia to invade surrounding tissues, blood vessels and lymphatics. A number of studies have demonstrated the significant roles of invadopodia in cancer. Therefore, the specific cells and molecules involved in invadopodia activity can provide as therapeutic targets. In this review, we included a thorough overview of studies in invadopodia and discussed their functions in cancer metastasis. We then presented the specific cells and molecules involved in invadopodia activity in pancreatic cancer and analyzed their suitability to be effective therapeutic targets. Currently, drugs targeting invadopodia and relevant clinical trials are negligible. Here, we highlighted the significance of potential drugs and discussed future obstacles in implementing clinical trials. This review presents a new perspective on invadopodia-induced pancreatic cancer metastasis and may prosper the development of targeted therapeutics against pancreatic cancer.

Matrix Degradation Assay to Measure the Ability of Tumor Cells to Degrade Extracellular Matrix

During the metastatic process, carcinoma cells form invadopodia, F-actin enriched protrusive structures, to degrade the extracellular matrix (ECM) in order to invade the surrounding stroma and intravasate into the circulatory system. In this chapter, we describe the 2D-fluorescent matrix degradation assay, a highly sensitive and reproducible in vitro method used to measure invadopodia-mediated ECM degradation. We provide a detailed protocol on how to prepare the glass coverslips with fluorescent gelatin matrix and a standardized method to quantify gelatin degradation and invadopodia formation in order to evaluate cell invasion.

A Fluorescent Gelatin Degradation Assay to Study Melanoma Breakdown of Extracellular Matrix

In order to protrude within a dense tissue, tumor cells have to develop the ability to digest the extracellular matrix (ECM). Melanoma cells, similarly to other types of tumor cells, form invadopodia, membranous invaginations rich in filamentous actin and several other proteins including matrix metalloproteinases (MMPs). MMPs degrade ECM structural proteins such as collagens, fibronectin, or laminin. Here we describe an assay that allows the detection of gelatinase activity exhibited by tumor cells under 2D conditions and methods to present obtained data in both a quantitative and a qualitative manner.

[Lidocaine in oncological surgery: the role of blocking in voltage-gated sodium channels. A narrative review]

BACKGROUND

The current evidence suggests that oncological surgery, which is a therapy used in the treatment of solid tumors, increases the risk of metastasis. In this regard, a wide range of tumor cells express Voltage-Gated Sodium Channels (VGSC), whose biological roles are not related to the generation of action potentials. In epithelial tumor cells, VGSC are part of cellular structures named invadopodia, involved in cell proliferation, migration, and metastasis. Recent studies showed that lidocaine could decrease cancer recurrence through its direct effects on tumor cells and immunomodulatory properties on the stress response.

OBJECTIVE

The aim of this narrative review is to highlight the role of VGSC in tumor cells, and to describe the potential antiproliferative effect of lidocaine during the pathogenesis of metastasis.

CONTENTS

A critical review of literature from April 2017 to April 2019 was performed. Articles found on PubMed (2000-2019) were considered. A free text and MeSH-lidocaine; voltage-gated sodium channels; tumor cells; invadopodia; surgical stress; cell proliferation; metastasis; cancer recurrence-for articles in English, Spanish and Portuguese language-was used. A total of 62 were selected.

CONCLUSION

In animal studies, lidocaine acts by blocking VGSC and other receptors, decreasing migration, invasion, and metastasis. These studies need to be replicated in humans in the context of oncological surgery.

Crosstalk between invadopodia and the extracellular matrix

The scaffold protein Tks5α is required for invadopodia-mediated cancer invasion both in vitro and in vivo. We have previously also revealed a role for Tks5 in tumor cell growth using three-dimensional (3D) culture model systems and mouse transplantation experiments. Here we use both 3D and high-density fibrillar collagen (HDFC) culture to demonstrate that native collagen-I, but not a form lacking the telopeptides, stimulated Tks5-dependent growth, which was dependent on the DDR collagen receptors. We used microenvironmental microarray (MEMA) technology to determine that laminin, fibronectin and tropoelastin also stimulated invadopodia formation. A Tks5α-specific monoclonal antibody revealed its expression both on microtubules and at invadopodia. High- and super-resolution microscopy of cells in and on collagen was then used to place Tks5α at the base of invadopodia, separated from much of the actin and cortactin, but coincident with both matrix metalloprotease and cathepsin proteolytic activity. Inhibition of the Src family kinases, cathepsins or metalloproteases all reduced invadopodia length but each had distinct effects on Tks5α localization. These studies highlight the crosstalk between invadopodia and extracellular matrix components, and reveal the invadopodium to be a spatially complex structure.

Differential regulation of rho GTPases during lung adenocarcinoma migration and invasion reveals a novel role of the tumor suppressor StarD13 in invadopodia regulation

Background

Lung cancer is the second most commonly occurring cancer. The ability to metastasize and spread to distant locations renders the tumor more aggressive. Members of the Rho subfamily of small GTP-binding proteins (GTPases) play a central role in the regulation of the actin cytoskeleton and in cancer cell migration and metastasis. In this study we investigated the role of the RhoA/Cdc42 GAP, StarD13, a previously described tumor suppressor, in malignancy, migration and invasion of the lung cancer cells A549.

Methods

We knocked down StarD13 expression in A549 lung cancer cells and tested the effect on cell migration and invadopodia formation using time lapse imaging and invasion assays. We also performed rescue experiments to determine the signaling pathways downstream of StarD13 and transfected the cells with FRET biosensors for RhoGTPases to identify the proteins involved in invadopodia formation.

Results

We observed a decrease in the level of expression of StarD13 in lung tumor tissues compared to normal lung tissues through immunohistochemistry. StarD13 also showed a lower expression in the lung adenocarcinoma cell line A549 compared to normal lung cells, WI38. In addition, the depletion of StarD13 increased cell proliferation and viability in WI38 and A549 cells, suggesting that StarD13 might potentially be a tumor suppressor in lung cancer. The depletion of StarD13, however, inhibited cell motility, conversely demonstrating a positive regulatory role in cell migration. This was potentially due to the constitutive activation of RhoA detected by pull down and FRET assays. Surprisingly, StarD13 suppressed cell invasion by inhibiting Cdc42-mediated invadopodia formation. Indeed, TKS4 staining and invadopodia assay revealed that StarD13 depletion increased Cdc42 activation as well as invadopodia formation and matrix degradation. Normal lung cells depleted of StarD13 also produced invadopodia, otherwise a unique hallmark of invasive cancer cells. Cdc42 knock down mimicked the effects of StarD13, while overexpression of a constitutively active Cdc42 mimicked the effects of its depletion. Finally, immunostaining and FRET analysis revealed the absence of StarD13 in invadopodia as compared to Cdc42, which was activated in invadopodia at the sites of matrix degradation.

Conclusion

In conclusion, StarD13 plays distinct roles in lung cancer cell migration and invasion through its differential regulation of Rho GTPases.

Insights and perspectives on calcium channel functions in the cockpit of cancerous space invaders

Development of metastasis causes the most serious clinical consequences of cancer and is responsible for over 90 % of cancer-related deaths. Hence, a better understanding of the mechanisms that drive metastasis formation appears critical for drug development designed to prevent the spread of cancer and related mortality. Metastasis dissemination is a multistep process supported by the increased motility and invasiveness capacities of tumor cells. To succeed in overcoming the mechanical constraints imposed by the basement membrane and surrounding tissues, cancer cells reorganize their focal adhesions or extend acto-adhesive cellular protrusions, called invadosomes, that can both contact the extracellular matrix and tune its degradation through metalloprotease activity. Over the last decade, accumulating evidence has demonstrated that altered Ca²⁺ channel activities and/or expression promote tumor cell-specific phenotypic changes, such as exacerbated migration and invasion capacities, leading to metastasis formation. While several studies have addressed the molecular basis of Ca²⁺ channel-dependent cancer cell migration, we are still far from having a comprehensive vision of the Ca²⁺ channel-regulated mechanisms of migration/invasion. This is especially true regarding the specific context of invadosome-driven invasion. This review aims to provide an overview of the current evidence supporting a central role for Ca²⁺ channel-dependent signaling in the regulation of these dynamic degradative structures. It will present available data on the few Ca²⁺ channels that have been studied in that specific context and discuss some potential interesting actors that have not been fully explored yet.

The role of the tumor microenvironment in tumor cell intravasation and dissemination

Metastasis, a process that requires tumor cell dissemination followed by tumor growth, is the primary cause of death in cancer patients. An essential step of tumor cell dissemination is intravasation, a process by which tumor cells cross the blood vessel endothelium and disseminate to distant sites. Studying this process is of utmost importance given that intravasation in the primary tumor, as well as the secondary and tertiary metastases, is the key step in the systemic spread of tumor cells, and that this process continues even after removal of the primary tumor. High-resolution intravital imaging of the tumor microenvironment of breast carcinoma has revealed that tumor cell intravasation exclusively occurs at doorways, termed "Tumor MicroEnvironment of Metastasis" (TMEM), composed of three different cell types: a Tie2^high/VEGF^high perivascular macrophage, a Mena overexpressing tumor cell, and an endothelial cell, all in direct contact. In this review article, we discuss the interactions between these cell types, the subsequent signaling events which lead to tumor cell intravasation, and the role of invadopodia in supporting tumor cell invasion and dissemination. We end our review by discussing how the knowledge acquired from the use of intravital imaging is now leading to new clinical trials targeting tumor cell dissemination and preventing metastatic progression.

Invadopodia: clearing the way for cancer cell invasion

The invasive nature of many cancer cells involves the formation of F-actin-based, lipid-raft-enriched membrane protrusions known as invadopodia or, more broadly, invadosomes. Invadopodia are specialized adhesive structures arising from ventral cell surface within cell-extracellular matrix (ECM) contacts and concentrate high proteolytic activities that allow cells to overcome the dense scaffold of local microenvironment, comprising a natural barrier to cell spreading. This degradative activity distinguishes invadopodia from other adhesive structures like focal adhesions, lamellipodia or filopodia, and is believed to drive cancer progression.

β1 integrin-mediated signaling regulates MT1-MMP phosphorylation to promote tumor cell invasion

Malignant cancer cells can invade extracellular matrix (ECM) through the formation of F-actin-rich subcellular structures termed invadopodia. ECM degradation at invadopodia is mediated by matrix metalloproteinases (MMPs), and recent findings indicate that membrane-anchored membrane type 1-matrix metalloproteinase (MT1-MMP, also known as MMP14) has a primary role in this process. Maintenance of an invasive phenotype is dependent on internalization of MT1-MMP from the plasma membrane and its recycling to sites of ECM remodeling. Internalization of MT1-MMP is dependent on its phosphorylation, and here we examine the role of β1 integrin-mediated signaling in this process. Activation of β1 integrin using the antibody P4G11 induced phosphorylation and internalization of MT1-MMP and resulted in increased cellular invasiveness and invadopodium formation in vitro We also observed phosphorylation of Src and epidermal growth factor receptor (EGFR) and an increase in their association in response to β1 integrin activation, and determined that Src and EGFR promote phosphorylation of MT1-MMP on Thr567 These results suggest that MT1-MMP phosphorylation is regulated by a β1 integrin-Src-EGFR signaling pathway that promotes recycling of MT1-MMP to sites of invadopodia formation during cancer cell invasion.This article has an associated First Person interview with the first author of the paper.

Role of hypoxia-related proteins in adenoid cystic carcinoma invasion

BACKGROUND

Among cancers affecting the oral cavity, adenoid cystic carcinoma (ACC) is a relatively common malignant neoplasm. It has high rates of metastasis and recurrence and is associated with significant morbidity. During the progression of ACC, the oxygen concentration is reduced in specific areas of the tumour microenvironment, leading to intratumoural hypoxia. The expression of NOTCH1, a disintegrin and metalloproteinase 12 (ADAM-12), hypoxia-inducible factor 1 alpha (HIF-1α), and heparin-binding epidermal growth factor (HB-EGF) under hypoxic conditions has been implicated in invadopodia formation, tumour invasiveness, and metastasis. The aim of this study was to analyse the expression of these proteins to elucidate the mechanisms underlying ACC invasiveness.

METHODS

Fifteen ACC samples and 10 normal-looking salivary gland (SG) samples were used to investigate the expression of these proteins by immunohistochemistry. Primary antibodies against NOTCH1, ADAM-12, HIF-1α, and HB-EGF were used.

RESULTS

The immunoexpression of all proteins was higher in ACC samples than in SG samples (p < 0.05).

CONCLUSIONS

There was increased expression of proteins associated with hypoxia and tumour invasiveness in ACC samples, which indicates a possible role of these proteins in the biological behaviour of this tumour.

Poji: a Fiji-based tool for analysis of podosomes and associated proteins

Podosomes are actin-based adhesion and invasion structures in a variety of cell types, with podosome-forming cells displaying up to several hundreds of these structures. Podosome number, distribution and composition can be affected by experimental treatments or during regular turnover, necessitating a tool that is able to detect even subtle differences in podosomal properties. Here, we present a Fiji-based macro code termed 'Poji' ('podosome analysis by Fiji'), which serves as an easy-to-use tool to characterize a variety of cellular and podosomal parameters, including area, fluorescence intensity, relative enrichment of associated proteins and radial podosome intensity profiles. This tool should be useful to gain more detailed insight into the regulation, architecture and functions of podosomes. Moreover, we show that Poji is easily adaptable for the analysis of invadopodia and associated extracellular matrix degradation, and likely also of other micron-size punctate structures. This article describes the workflow of the Poji macro, presents several examples of its applications, and also points out limitations, as well as respective solutions, and adaptable features to streamline the analysis.This article has an associated First Person interview with the first author of the paper.

The chemokine CCL7 regulates invadopodia maturation and MMP-9 mediated collagen degradation in liver-metastatic carcinoma cells

Liver metastases remain a major cause of death from gastrointestinal tract cancers and other malignancies, such as breast and lung carcinomas. Understanding the underlying biology is essential for the design of effective therapies. We previously identified the chemokine CCL7 and its receptor CCR3 as critical mediators of invasion and metastasis in lung and colon carcinoma cells. Here we show that the CCL7/CCR3 axis regulates a late stage in invadopodia genesis namely, the targeting of MMP-9 to the invadopodia complex, thereby promoting invadopodia maturation and collagen degradation. We show that this process could be blocked by overexpression of a dominant negative RhoA in highly invasive cells, while a constitutively active RhoA upregulated invadopodia maturation in CCL7-silenced and poorly invasive and metastatic cells and also enhanced their metastatic potential in vivo, collectively, implicating RhoA activation in signaling downstream of CCL7. Blockade of the ERK or PI3K pathways by chemical inhibitors also inhibited invadopodia formation, but affected the initiation stage of invadopodia genesis. Our data implicate CCL7/CCR3 signaling in invadopodia maturation and suggest that chemokine signaling acts in concert with extracellular matrix-initiated signals to promote invasion and liver metastasis.

Ubiquitination of Src promotes its secretion via small extracellular vesicles

Upregulation of the Src tyrosine kinase is implicated in the progression of cancer. The oncogenic potential of Src is suppressed via several negative regulation systems including degradation via the ubiquitin-proteasome pathway. Here, we show that ubiquitination of Src promotes its secretion via small extracellular vesicles (sEVs) to suppress its oncogenic potential. In MDCK cells expressing a modified Src that can be activated by hydroxytamoxifen, activated Src was transported to late endosomes/lysosomes and secreted via sEVs. The secretion of Src was suppressed by ablation of Cbl E3-ligase, suggesting the contribution of ubiquitination to this process. Activated Src was ubiquitinated at multiple sites, and Lys429 was identified as a critical site for sEV-mediated secretion. Mutation of Src at Lys429 (R429) caused resistance to ubiquitination and decreased its secretion via sEVs. The activated R429 mutant was also transported to late endosomes/lysosomes, whereas its incorporation into intraluminal vesicles was reduced. Activation of the R429 mutant induced a greater FAK activation than that of wild-type Src, thereby potentiating Src-induced invasive phenotypes, such as invadopodia formation and invasive activity. These findings demonstrate that ubiquitination of activated Src at Lys429 promotes its secretion via sEVs, suggesting a potential strategy to suppress the oncogenic function of upregulated Src.

Acidosis and proteolysis in the tumor microenvironment

The glycolytic phenotype of the Warburg effect is associated with acidification of the tumor microenvironment. In this review, we describe how acidification of the tumor microenvironment may increase the invasive and degradative phenotype of cancer cells. As a template of an extracellular acidic microenvironment that is linked to proteolysis, we use the resorptive pit formed between osteoclasts and bone. We describe similar changes that have been observed in cancer cells in response to an acidic microenvironment and that are associated with proteolysis and invasive and metastatic phenotypes. This includes consideration of changes observed in the intracellular trafficking of vesicles, i.e., lysosomes and exosomes, and in specialized regions of the membrane, i.e., invadopodia and caveolae. Cancer-associated cells are known to affect what is generally referred to as tumor proteolysis but little direct evidence for this being regulated by acidosis; we describe potential links that should be verified.

Moesin facilitates metastasis of hepatocellular carcinoma cells by improving invadopodia formation and activating β-catenin/MMP9 axis

Moesin has been proved to be implicated in invasiveness and metastasis in many other cancers, but unclear in HCC. Thus, this study was performed to investigate the clinical significance of moesin and its biological functions in HCC. The results showed that moesin was significantly up-regulated in HCC tissues and was an independent prognostic factor for predicting the recurrence of HCC patients, postoperatively. Furthermore, we also demonstrated that moesin promoted the migration and invasion of HCC cells in vitro and in vivo. And the mechanism studies indicated that moesin overexpression increased the formation of invadopodia and improved the activation of β-catenin/MMP9 axis. Taken together, our findings revealed that moesin acted as an important onco-protein participating in the metastasis of HCC.

MiR-612 regulates invadopodia of hepatocellular carcinoma by HADHA-mediated lipid reprogramming

Background

MicroRNA-612 (miR-612) has been proven to suppress EMT, stemness, and tumor metastasis of hepatocellular carcinoma (HCC) via PI3K/AKT2 and Sp1/Nanog signaling. However, its biological roles on HCC progression are far from elucidated.

Methods

We found direct downstream target of miR-612, hadha by RNA immunoprecipitation and sequencing. To explore its biological characteristic, potential molecular mechanism, and clinical relevance in HCC patients, we performed several in-vitro and in-vivo models, as well as human tissue chip.

Results

Ectopic expression of miR-612 could partially reverse the level of HADHA, then suppress function of pseudopods, and diminish metastatic and invasive potential of HCC by lipid reprogramming. In detail, miR-612 might reduce invadopodia formation via HADHA-mediated cell membrane cholesterol alteration and accompanied with the inhibition of Wnt/β-catenin regulated EMT occurrence. Our results showed that the maximum oxygen consumption rates (OCR) of HCCLM3^miR-612-OE and HCCLM3^hadha-KD cells were decreased nearly by 40% and 60% of their counterparts (p < 0.05). The levels of acetyl CoA were significantly decreased, about 1/3 (p > 0.05) or 1/2 (p < 0.05) of their controls, in exogenous miR-612 or hadha-shRNA transfected HCCLM3 cell lines. Besides, overexpression of hadha cell lines had a high expression level of total cholesterol, especially 27-hydroxycholesterol (p < 0.005). SREBP2 protein expression level as well as its downstream targets, HMGCS1, HMGCR, MVD, SQLE were all deregulated by HADHA. Meanwhile, the ATP levels were reduced to 1/2 and 1/4 in HCCLM3^miR-612-OE (p < 0.05) and HCCLM3^hadha-KD (p < 0.01) respectively. Moreover, patients with low miR-612 levels and high HADHA levels had a poor prognosis with shorter overall survival.

Conclusion

miR-612 can suppress the formation of invadopodia, EMT, and HCC metastasis and by HADHA-mediated lipid programming, which may provide a new insight of miR-612 on tumor metastasis and progression.

IKKε phosphorylates kindlin-2 to induce invadopodia formation and promote colorectal cancer metastasis

Invadopodia formation is a key driver of cancer metastasis. The noncanonical IkB-related kinase IKKε has been implicated in cancer metastasis, but its roles in invadopodia formation and colorectal cancer (CRC) metastasis are unclear. Methods: Immunofluorescence, gelatin-degradation assay, wound healing assay and transwell invasion assay were used to determine the influence of IKKε over-expression, knockdown and pharmacological inhibition on invadopodia formation and the migratory and invasive capacity of CRC cells in vitro. Effects of IKKε knockdown or pharmacological inhibition on CRC metastasis were examined in mice. Immunohistochemistry staining was used to detect expression levels of IKKε in CRC patient tissues, and its association with prognosis in CRC patients was also analyzed. Immunoprecipitation, western blotting and in vitro kinase assay were constructed to investigate the molecular mechanisms. Results: IKKε co-localizes with F-actin and the invadopodia marker Tks5 at the gelatin-degrading sites of CRC cells. Genetic over-expression/knockdown or pharmacological inhibition of IKKε altered invadopodia formation and the migratory and invasive capacity of CRC cells in vitro. In vivo, knockdown or pharmacological inhibition of IKKε significantly suppressed metastasis of CRC cells in mice. IKKε knockdown also inhibited invadopodia formation in vivo. Clinical investigation of tumor specimens from 191 patients with CRC revealed that high IKKε expression correlates with metastasis and poor prognosis of CRC. Mechanistically, IKKε directly binds to and phosphorylates kindlin-2 at serine 159; this effect mediates the IKKε-induced invadopodia formation and promotion of CRC metastasis. Conclusions: We identify IKKε as a novel regulator of invadopodia formation and a unique mechanism by which IKKε promotes the metastasis of CRC. Our study suggests that IKKε is a potential target to suppress CRC metastasis.

Rho GTPases and related signaling complexes in cell migration and invasion

Cell migration and invasion play an important role in the development of cancer. Cell migration is associated with several specific actin filament-based structures, including lamellipodia, filopodia, invadopodia and blebs, and with cell-cell adhesion, cell-extracellular matrix adhesion. Migration occurs via different modes, human epithelial cancer cells mainly migrate collectively, while in vivo imaging studies in laboratory animals have found that most cells migrate as single cells. Rho GTPases play an important role in the process of cell migration, and several Rho GTPase-related signaling complexes are also involved. However, the exact mechanism by which these signaling complexes act remains unclear. This paper reviews how Rho GTPases and related signaling complexes interact with other proteins, how their expression is regulated, how tumor microenvironment-related factors play a role in invasion and metastasis, and the mechanism of these complex signaling networks in cell migration and invasion.

TIMP-2 secreted by monocyte-like cells is a potent suppressor of invadopodia formation in pancreatic cancer cells

BACKGROUND

Monocytes are a major component of the tumor microenvironment (TME) in pancreatic ductal adenocarcinoma (PDAC). However, the complex interactions between tumor cells and monocytes and their role in tumor invasion have not been fully established.

METHODS

To specifically test the impact of interaction on invasive potential two PDAC cell lines PaTu8902 and CFPAC-1 were selected on their ability to form invasive adhesions, otherwise known as invadopodia and invade in a spheroid invasion assay.

RESULTS

Interestingly when the PDAC cells were co-cultured with undifferentiated THP1 monocyte-like cells invadopodia formation was significantly suppressed. Moreover, conditioned media of THP1 cells (CM) was also able to suppress invadopodia formation. Further investigation revealed that both tissue inhibitor of metalloproteinase (TIMP) 1 and 2 were present in the CM. However, suppression of invadopodia formation was found that was specific to TIMP2 activity.

CONCLUSIONS

Our findings indicate that TIMP2 levels in the tumour microenvironment may have prognostic value in patients with PDAC. Furthermore, activation of TIMP2 expressing monocytes in the primary tumour could present a potential therapeutic opportunity to suppress cell invasion in PDAC.

MT4-MMP promotes invadopodia formation and cell motility in FaDu head and neck cancer cells

Hypoxia-inducible factor-1α (HIF-1α) induces cancer metastasis. We previously demonstrated that HIF-1α-induced membrane-type 4 matrix metalloproteinase (MT4-MMP) is involved in hypoxia-mediated metastasis in head and neck squamous cell carcinoma (HNSCC). However, the functions and detailed mechanisms of MT4-MMP in cancer metastasis are not well understood. In this study, we investigated whether MT4-MMP regulates invadopodia formation or individual cell movement-both critical to cancer migration and invasion-in three-dimensional (3D) environments. By expressing MT4-MMP in the HNSCC cell line FaDu, we demonstrated that MT4-MMP increases invadopodia formation and gelatin degradation. Furthermore, the amoeboid-like cell movement on collagen gel was increased by MT4-MMP expression in FaDu cells. Mechanistically, MT4-MMP may induce invadopodia formation by binding with Tks5 and PDGFRα to result in Src activation and promote amoeboid-like movement by stimulating the small GTPases Rho and Cdc42. Altogether, our data indicate that MT4-MMP induces two crucial mechanisms of cancer dissemination, invadopodia formation and amoeboid movement, and elucidate the prometastatic role of MT4-MMP in hypoxia-mediated cancer metastasis.

Invadopodia-mediated ECM degradation is enhanced in the G1 phase of the cell cycle

The process of tumor cell invasion and metastasis includes assembly of invadopodia, protrusions capable of degrading the extracellular matrix (ECM). The effect of cell cycle progression on invadopodia has not been elucidated. In this study, by using invadopodia and cell cycle fluorescent markers, we show in 2D and 3D cultures, as well as in vivo, that breast carcinoma cells assemble invadopodia and invade into the surrounding ECM preferentially during the G1 phase. The expression (MT1-MMP, also known as MMP14, and cortactin) and localization (Tks5; also known as SH3PXD2A) of invadopodia components are elevated in G1 phase, and cells synchronized in G1 phase exhibit significantly higher ECM degradation compared to the cells synchronized in S phase. The cyclin-dependent kinase inhibitor (CKI) p27^kip1 (also known as CDKN1B) localizes to the sites of invadopodia assembly. Overexpression and stable knockdown of p27^kip1 lead to contrasting effects on invadopodia turnover and ECM degradation. Taken together, these findings suggest that expression of invadopodia components, as well as invadopodia function, are linked to cell cycle progression, and that invadopodia are controlled by cell cycle regulators. Our results caution that this coordination between invasion and cell cycle must be considered when designing effective chemotherapies.

TGF-β-induced transgelin promotes bladder cancer metastasis by regulating epithelial-mesenchymal transition and invadopodia formation

Background

Metastatic bladder cancer (BLCA) is a lethal disease with an unmet need for study. Transgelin (TAGLN) is an actin-binding protein that affects the dynamics of the actin cytoskeleton indicating its robust potential as a metastasis initiator. Here, we sought to explore the expression pattern of TAGLN and elucidate its specific functioning and mechanisms in BLCA.

Methods

A comprehensive assessment of TAGLN expression in BLCA was performed in three cohorts with a total of 847 patients. The potential effects of TAGLN on BLCA were further determined using clinical genomic analyses that guided the subsequent functional and mechanistic studies. In vitro migration, invasion assays and in vivo metastatic mouse model were performed to explore the biological functions of TAGLN in BLCA cells. Immunofluorescence, western blot and correlation analysis were used to investigate the molecular mechanisms of TAGLN.

Findings

TAGLN was highly expressed in BLCA and correlated with advanced prognostic features. TAGLN promoted cell colony formation and cell migration and invasion both in vitro and in vivo by inducing invadopodia formation and epithelial-mesenchymal transition, during which a significant correlation between TAGLN and Slug was observed. The progression-dependent correlation between TGF-β and TAGLN was analysed at both the cellular and tissue levels, while TGF-β-mediated migration was abolished by the suppression of TAGLN.

Interpretation

Overall, TAGLN is a promising novel prognosis biomarker of BLCA, and its metastatic mechanisms indicate that TAGLN may represent a novel target agent that can be utilized for the clinical management of invasive and metastatic BLCA.

Fund

This work was supported by the National Natural Science Foundation of China [81772703, 81672546, 81602253]; the Natural Science Foundation of Beijing [71772219, 7152146]. and Innovative Fund for Doctoral Students of Peking University Health Science Center (BUM2018BSS002). Funders had no role in the design of the study, data collection, data analysis, interpretation, or the writing of this report.