Mechanotransduction pulls the strings of matrix degradation at invadosome

Invadosome Formation by Lung Fibroblasts in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterized by abnormal fibroblast accumulation in the lung leading to extracellular matrix deposition and remodeling that compromise lung function. However, the mechanisms of interstitial invasion and remodeling by lung fibroblasts remain poorly understood. The invadosomes, initially described in cancer cells, consist of actin-based adhesive structures that coordinate with numerous other proteins to form a membrane protrusion capable of degrading the extracellular matrix to promote their invasive phenotype. In this regard, we hypothesized that invadosome formation may be increased in lung fibroblasts from patients with IPF. Public RNAseq datasets from control and IPF lung tissues were used to identify differentially expressed genes associated with invadosomes. Lung fibroblasts isolated from bleomycin-exposed mice and IPF patients were seeded with and without the two approved drugs for treating IPF, nintedanib or pirfenidone on fluorescent gelatin-coated coverslips for invadosome assays. Several matrix and invadosome-associated genes were increased in IPF tissues and in IPF fibroblastic foci. Invadosome formation was significantly increased in lung fibroblasts isolated from bleomycin-exposed mice and IPF patients. The degree of lung fibrosis found in IPF tissues correlated strongly with invadosome production by neighboring cells. Nintedanib suppressed IPF and PDGF-activated lung fibroblast invadosome formation, an event associated with inhibition of the PDGFR/PI3K/Akt pathway and TKS5 expression. Fibroblasts derived from IPF lung tissues express a pro-invadosomal phenotype, which correlates with the severity of fibrosis and is responsive to antifibrotic treatment.

Compression enhances invasive phenotype and matrix degradation of breast Cancer cells via Piezo1 activation

Background

Uncontrolled growth in solid breast cancer generates mechanical compression that may drive the cancer cells into a more invasive phenotype, but little is known about how such compression affects the key events and corresponding regulatory mechanisms associated with invasion of breast cancer cells including cellular behaviors and matrix degradation.

Results

Here we show that compression enhanced invasion and matrix degradation of breast cancer cells. We also identified Piezo1 as the putative mechanosensitive cellular component that transmitted compression to not only enhance the invasive phenotype, but also induce calcium influx and downstream Src signaling. Furthermore, we demonstrated that Piezo1 was mainly localized in caveolae, and both Piezo1 expression and compression-enhanced invasive phenotype of the breast cancer cells were reduced when caveolar integrity was compromised by either knocking down caveolin1 expression or depleting cholesterol content.

Conclusions

Taken together, our data indicate that mechanical compression activates Piezo1 channels to mediate enhanced breast cancer cell invasion, which involves both cellular events and matrix degradation. This may be a critical mechanotransduction pathway during breast cancer metastasis, and thus potentially a novel therapeutic target for the disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12860-021-00401-6.

Tumor Cellular and Microenvironmental Cues Controlling Invadopodia Formation

During the metastatic progression, invading cells might achieve degradation and subsequent invasion into the extracellular matrix (ECM) and the underlying vasculature using invadopodia, F-actin-based and force-supporting protrusive membrane structures, operating focalized proteolysis. Their formation is a dynamic process requiring the combined and synergistic activity of ECM-modifying proteins with cellular receptors, and the interplay with factors from the tumor microenvironment (TME). Significant advances have been made in understanding how invadopodia are assembled and how they progress in degradative protrusions, as well as their disassembly, and the cooperation between cellular signals and ECM conditions governing invadopodia formation and activity, holding promise to translation into the identification of molecular targets for therapeutic interventions. These findings have revealed the existence of biochemical and mechanical interactions not only between the actin cores of invadopodia and specific intracellular structures, including the cell nucleus, the microtubular network, and vesicular trafficking players, but also with elements of the TME, such as stromal cells, ECM components, mechanical forces, and metabolic conditions. These interactions reflect the complexity and intricate regulation of invadopodia and suggest that many aspects of their formation and function remain to be determined. In this review, we will provide a brief description of invadopodia and tackle the most recent findings on their regulation by cellular signaling as well as by inputs from the TME. The identification and interplay between these inputs will offer a deeper mechanistic understanding of cell invasion during the metastatic process and will help the development of more effective therapeutic strategies.

Mechanical Cues Affect Migration and Invasion of Cells From Three Different Directions

Cell migration and invasion is a key driving factor for providing essential cellular functions under physiological conditions or the malignant progression of tumors following downward the metastatic cascade. Although there has been plentiful of molecules identified to support the migration and invasion of cells, the mechanical aspects have not yet been explored in a combined and systematic manner. In addition, the cellular environment has been classically and frequently assumed to be homogeneous for reasons of simplicity. However, motility assays have led to various models for migration covering only some aspects and supporting factors that in some cases also include mechanical factors. Instead of specific models, in this review, a more or less holistic model for cell motility in 3D is envisioned covering all these different aspects with a special emphasis on the mechanical cues from a biophysical perspective. After introducing the mechanical aspects of cell migration and invasion and presenting the heterogeneity of extracellular matrices, the three distinct directions of cell motility focusing on the mechanical aspects are presented. These three different directions are as follows: firstly, the commonly used invasion tests using structural and structure-based mechanical environmental signals; secondly, the mechano-invasion assay, in which cells are studied by mechanical forces to migrate and invade; and thirdly, cell mechanics, including cytoskeletal and nuclear mechanics, to influence cell migration and invasion. Since the interaction between the cell and the microenvironment is bi-directional in these assays, these should be accounted in migration and invasion approaches focusing on the mechanical aspects. Beyond this, there is also the interaction between the cytoskeleton of the cell and its other compartments, such as the cell nucleus. In specific, a three-element approach is presented for addressing the effect of mechanics on cell migration and invasion by including the effect of the mechano-phenotype of the cytoskeleton, nucleus and the cell's microenvironment into the analysis. In precise terms, the combination of these three research approaches including experimental techniques seems to be promising for revealing bi-directional impacts of mechanical alterations of the cellular microenvironment on cells and internal mechanical fluctuations or changes of cells on the surroundings. Finally, different approaches are discussed and thereby a model for the broad impact of mechanics on cell migration and invasion is evolved.

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.

Covalent cross-linking of basement membrane-like matrices physically restricts invasive protrusions in breast cancer cells

The basement membrane (BM) provides a physical barrier to invasion in epithelial tumors, and alterations in the molecular makeup and structural integrity of the BM have been implicated in cancer progression. Invadopodia are the invasive protrusions that enable cancer cells to breach the nanoporous basement membrane, through matrix degradation and generation of force. However, the impact of covalent cross-linking on invadopodia extension into the BM remains unclear. Here, we examine the impact of covalent cross-linking of extracellular matrix on invasive protrusions using biomaterials that present ligands relevant to the basement membrane and provide a nanoporous, confining microenvironment. We find that increased covalent cross-linking of reconstituted basement membrane (rBM) matrix diminishes matrix mechanical plasticity, or the ability of the matrix to permanently retain deformation due to force. Covalently cross-linked rBM matrices, and rBM-alginate interpenetrating networks (IPNs) with covalent cross-links and low plasticity, restrict cell spreading and protrusivity. The reduced spreading and reduced protrusivity in response to low mechanical plasticity occurred independent of proteases. Mechanistically, our computational model reveals that the reduction in mechanical plasticity due to covalent cross-linking is sufficient to mechanically prevent cell protrusions from extending, independent of the impact of covalent cross-linking or matrix mechanical plasticity on cell signaling pathways. These findings highlight the biophysical role of covalent cross-linking in regulating basement membrane plasticity, as well as cancer cell invasion of this confining tissue layer.

New Routes in GPCR/β-Arrestin-Driven Signaling in Cancer Progression and Metastasis

Tumor cells acquire invasive and metastatic behavior by sensing changes in the localization and activation of signaling pathways, which in turn determine changes in actin cytoskeleton. The core-scaffold machinery associated to β-arrestin (β-arr) is a key mechanism of G-protein coupled receptors (GPCR) to achieve spatiotemporal specificity of different signaling complexes driving cancer progression. Within different cellular contexts, the scaffold proteins β-arr1 or β-arr2 may now be considered organizers of protein interaction networks involved in tumor development and metastatic dissemination. Studies have uncovered the importance of the β-arr engagement with a growing number of receptors, signaling molecules, cytoskeleton regulators, epigenetic modifiers, and transcription factors in GPCR-driven tumor promoting pathways. In many of these molecular complexes, β-arrs might provide a physical link to active dynamic cytoskeleton, permitting cancer cells to adapt and modify the tumor microenvironment to promote the metastatic spread. Given the complexity and the multidirectional β-arr-driven signaling in cancer cells, therapeutic targeting of specific GPCR/β-arr molecular mechanisms is an important avenue to explore when considering future new therapeutic options. The focus of this review is to integrate the most recent developments and exciting findings of how highly connected components of β-arr-guided molecular connections to other pathways allow precise control over multiple signaling pathways in tumor progression, revealing ways of therapeutically targeting the convergent signals in patients.

Piezo2 channel regulates RhoA and actin cytoskeleton to promote cell mechanobiological responses

Actin polymerization and assembly into stress fibers (SFs) is central to many cellular processes. However, how SFs form in response to the mechanical interaction of cells with their environment is not fully understood. Here we have identified Piezo2 mechanosensitive cationic channel as a transducer of environmental physical cues into mechanobiological responses. Piezo2 is needed by brain metastatic cells from breast cancer (MDA-MB-231-BrM2) to probe their physical environment as they anchor and pull on their surroundings or when confronted with confined migration through narrow pores. Piezo2-mediated Ca²⁺ influx activates RhoA to control the formation and orientation of SFs and focal adhesions (FAs). A possible mechanism for the Piezo2-mediated activation of RhoA involves the recruitment of the Fyn kinase to the cell leading edge as well as calpain activation. Knockdown of Piezo2 in BrM2 cells alters SFs, FAs, and nuclear translocation of YAP; a phenotype rescued by overexpression of dominant-positive RhoA or its downstream effector, mDia1. Consequently, hallmarks of cancer invasion and metastasis related to RhoA, actin cytoskeleton, and/or force transmission, such as migration, extracellular matrix degradation, and Serpin B2 secretion, were reduced in cells lacking Piezo2.

Transient mechanical strain promotes the maturation of invadopodia and enhances cancer cell invasion in vitro

Cancer cell invasion is influenced by various biomechanical forces found within the microenvironment. We have previously found that invasion is enhanced in fibrosarcoma cells when transient mechanical stimulation is applied within an in vitro mechano-invasion assay. This enhancement of invasion is dependent on cofilin (CFL1), a known regulator of invadopodia maturation. Invadopodia are actin-rich structures present in invasive cancer cells that are enzymatically active and degrade the surrounding extracellular matrix to facilitate invasion. In this study, we examine changes in gene expression in response to tugging on matrix fibers. Interestingly, we find that integrin β3 expression is downregulated and leads to an increase in cofilin activity, as evidenced by a reduction in its Ser3 phosphorylation levels. As a result, invadopodia lengthen and have increased enzymatic activity, indicating that transient mechanical stimulation promotes the maturation of invadopodia leading to increased levels of cell invasion. Our results are unique in defining an invasive mechanism specific to the invasive process of cancer cells that is triggered by tugging forces in the microenvironment, as opposed to rigidity, compression or stretch forces.

Reciprocal relationship between membrane type 1 matrix metalloproteinase and the algesic peptides of myelin basic protein contributes to chronic neuropathic pain

Myelin basic protein (MBP) is an auto-antigen able to induce intractable pain from innocuous mechanical stimulation (mechanical allodynia). The mechanisms provoking this algesic MBP activity remain obscure. Our present study demonstrates that membrane type 1 matrix metalloproteinase (MT1-MMP/MMP-14) releases the algesic MBP peptides from the damaged myelin, which then reciprocally enhance the expression of MT1-MMP in nerve to sustain a state of allodynia. Specifically, MT1-MMP expression and activity in rat sciatic nerve gradually increased starting at day 3 after chronic constriction injury (CCI). Inhibition of the MT1-MMP activity by intraneural injection of the function-blocking human DX2400 monoclonal antibody at day 3 post-CCI reduced mechanical allodynia and neuropathological signs of Wallerian degeneration, including axon demyelination, degeneration, edema and formation of myelin ovoids. Consistent with its role in allodynia, the MT1-MMP proteolysis of MBP generated the MBP69-86-containing epitope sequences in vitro. In agreement, the DX2400 therapy reduced the release of the MBP69-86 epitope in CCI nerve. Finally, intraneural injection of the algesic MBP69-86 and control MBP2-18 peptides differentially induced MT1-MMP and MMP-2 expression in the nerve. With these data we offer a novel, self-sustaining mechanism of persistent allodynia via the positive feedback loop between MT1-MMP and the algesic MBP peptides. Accordingly, short-term inhibition of MT1-MMP activity presents a feasible pharmacological approach to intervene in this molecular circuit and the development of neuropathic pain.