Coordinated Regulation of Intracellular Fascin Distribution Governs Tumor Microvesicle Release and Invasive Cell Capacity

The crucial role of fascin-1 in the pathogenesis, metastasis, and chemotherapeutic resistance of breast cancer

Breast cancer (BC) is the most common type of cancer in women to be diagnosed, and it is also the second leading cause of cancer death in women globally. It is the disease that causes the most life years adjusted for disability lost among women, making it a serious worldwide health issue. Understanding and interpreting carcinogenesis and metastatic pathways is critical for curing malignancy. Fascin-1 was recognized as an actin-bundling protein with parallel, rigid bundles as a result of the cross-linking of F-actin microfilaments. Increasing levels of fascin-1 have been associated with bad prognostic profiles, aggressiveness of clinical courses, and poor survival outcomes in a variety of human malignancies. Cancer cells that overexpress fascin-1 have higher capabilities for proliferation, invasion, migration, and metastasis. Fascin-1 is being considered as a potential target for therapy as well as a potential biomarker for diagnostics in a variety of cancer types. This review aims to provide an overview of the FSCN1 gene and its protein structure, elucidate its physiological and pathological roles, and throw light on its involvement in the initiation, development, and chemotherapeutic resistance of BC.

Effects on exocytosis by two HSV-1 mutants unable to block autophagy

IMPORTANCE

Pathogens often hijack extracellular vesicle (EV) biogenesis pathways for assembly, egress, and cell-to-cell spread. Herpes simplex virus 1 (HSV-1) infection stimulated EV biogenesis through a CD63 tetraspanin biogenesis pathway and these EVs activated antiviral responses in recipient cells restricting the infection. HSV-1 inhibits autophagy to evade the host, and increased CD63 exocytosis could be a coping mechanism, as CD63 is involved in both cargo delivery to lysosomes during autophagy and exocytosis. We analyzed exocytosis after infection with two HSV-1 mutants, a ΔICP34.5 and a ΔICP0, that could not inhibit autophagy. Unlike HSV-1(F), neither of these viruses stimulated increased EV biogenesis through the CD63 pathway. ΔICP34.5 stimulated production of microvesicles and apoptotic bodies that were CD63-negative, while ΔICP0 displayed an overall reduced production of EVs. These EVs activated innate immunity gene expression in recipient cells. Given the potential use of these mutants for therapeutic purposes, the immunomodulatory properties of EVs associated with them may be beneficial.

Pathological and Therapeutic Significance of Tumor-Derived Extracellular Vesicles in Cancer Cell Migration and Metastasis

The infiltration of primary tumors and metastasis formation at distant sites strongly impact the prognosis and the quality of life of cancer patients. Current therapies including surgery, radiotherapy, and chemotherapy are limited in targeting the complex cell migration mechanisms responsible for cancer cell invasiveness and metastasis. A better understanding of these mechanisms and the development of new therapies are urgently needed. Extracellular vesicles (EVs) are lipid-enveloped particles involved in inter-tissue and inter-cell communication. This review article focuses on the impact of EVs released by tumor cells, specifically on cancer cell migration and metastasis. We first introduce cell migration processes and EV subtypes, and we give an overview of how tumor-derived EVs (TDEVs) may impact cancer cell migration. Then, we discuss ongoing EV-based cancer therapeutic approaches, including the inhibition of general EV-related mechanisms as well as the use of EVs for anti-cancer drug delivery, focusing on the harnessing of TDEVs. We propose a protein-EV shuttle as a route alternative to secretion or cell membrane binding, influencing downstream signaling and the final effect on target cells, with strong implications in tumorigenesis. Finally, we highlight the pitfalls and limitations of therapeutic EV exploitation that must be overcome to realize the promise of EVs for cancer therapy.

Extracellular Vesicles in Neurodegenerative Diseases: An Update

Neurodegenerative diseases affect millions of people worldwide. The likelihood of developing a neurodegenerative disease rises dramatically as life expectancy increases. Although it has drawn significant attention, there is still a lack of proper effective treatments for neurodegenerative disease because the mechanisms of its development and progression are largely unknown. Extracellular vesicles (EVs) are small bi-lipid layer-enclosed nanosized particles in tissues and biological fluids. EVs are emerging as novel intercellular messengers and regulate a series of biological responses. Increasing evidence suggests that EVs are involved in the pathogenesis of neurodegenerative disorders. In this review, we summarize the recent findings of EVs in neurodegenerative diseases and bring up the limitations in the field.

Preclinical-to-clinical Anti-cancer Drug Response Prediction and Biomarker Identification Using TINDL

Prediction of the response of cancer patients to different treatments and identification of biomarkers of drug response are two major goals of individualized medicine. Here, we developed a deep learning framework called TINDL, completely trained on preclinical cancer cell lines (CCLs), to predict the response of cancer patients to different treatments. TINDL utilizes a tissue-informed normalization to account for the tissue type and cancer type of the tumors and to reduce the statistical discrepancies between CCLs and patient tumors. Moreover, by making the deep learning black box interpretable, this model identifies a small set of genes whose expression levels are predictive of drug response in the trained model, enabling identification of biomarkers of drug response. Using data from two large databases of CCLs and cancer tumors, we showed that this model can distinguish between sensitive and resistant tumors for 10 (out of 14) drugs, outperforming various other machine learning models. In addition, our small interfering RNA (siRNA) knockdown experiments on 10 genes identified by this model for one of the drugs (tamoxifen) confirmed that tamoxifen sensitivity is substantially influenced by all of these genes in MCF7 cells, and seven of these genes in T47D cells. Furthermore, genes implicated for multiple drugs pointed to shared mechanism of action among drugs and suggested several important signaling pathways. In summary, this study provides a powerful deep learning framework for prediction of drug response and identification of biomarkers of drug response in cancer. The code can be accessed at https://github.com/ddhostallero/tindl.

Extracellular Vesicles for Therapeutic Nucleic Acid Delivery: Loading Strategies and Challenges

Extracellular vesicles (EVs) are membrane vesicles released into the extracellular milieu by cells of various origins. They contain different biological cargoes, protecting them from degradation by environmental factors. There is an opinion that EVs have a number of advantages over synthetic carriers, creating new opportunities for drug delivery. In this review, we discuss the ability of EVs to function as carriers for therapeutic nucleic acids (tNAs), challenges associated with the use of such carriers in vivo, and various strategies for tNA loading into EVs.

Spatial regulation of the glycocalyx component podocalyxin is a switch for prometastatic function

The glycocalyx component and sialomucin podocalyxin (PODXL) is required for normal tissue development by promoting apical membranes to form between cells, triggering lumen formation. Elevated PODXL expression is also associated with metastasis and poor clinical outcome in multiple tumor types. How PODXL presents this duality in effect remains unknown. We identify an unexpected function of PODXL as a decoy receptor for galectin-3 (GAL3), whereby the PODXL-GAL3 interaction releases GAL3 repression of integrin-based invasion. Differential cortical targeting of PODXL, regulated by ubiquitination, is the molecular mechanism controlling alternate fates. Both PODXL high and low surface levels occur in parallel subpopulations within cancer cells. Orthotopic intraprostatic xenograft of PODXL-manipulated cells or those with different surface levels of PODXL define that this axis controls metastasis in vivo. Clinically, interplay between PODXL-GAL3 stratifies prostate cancer patients with poor outcome. Our studies define the molecular mechanisms and context in which PODXL promotes invasion and metastasis.

Tumor-Derived Extracellular Vesicles: Multifunctional Entities in the Tumor Microenvironment

Tumor cells release extracellular vesicles (EVs) that can function as mediators of intercellular communication in the tumor microenvironment. EVs contain a host of bioactive cargo, including membrane, cytosolic, and nuclear proteins, in addition to noncoding RNAs, other RNA types, and double-stranded DNA fragments. These shed vesicles may deposit paracrine information and can also be taken up by stromal cells, causing the recipient cells to undergo phenotypic changes that profoundly impact diverse facets of cancer progression. For example, this unique form of cellular cross talk helps condition the premetastatic niche, facilitates evasion of the immune response, and promotes invasive and metastatic activity. These findings, coupled with those demonstrating that the number and content of EVs produced by tumors can vary depending on their tumor of origin, disease stage, or response to therapy, have raised the exciting possibility that EVs can be used for risk stratification, diagnostic, and even prognostic purposes. We summarize recent developments and the current knowledge of EV cargoes, their impact on disease progression, and implementation of EV-based liquid biopsies as tumor biomarkers.

How does plasticity of migration help tumor cells to avoid treatment: Cytoskeletal regulators and potential markers

Tumor shrinkage as a result of antitumor therapy is not the only and sufficient indicator of treatment success. Cancer progression leads to dissemination of tumor cells and formation of metastases - secondary tumor lesions in distant organs. Metastasis is associated with acquisition of mobile phenotype by tumor cells as a result of epithelial-to-mesenchymal transition and further cell migration based on cytoskeleton reorganization. The main mechanisms of individual cell migration are either mesenchymal, which depends on the activity of small GTPase Rac, actin polymerization, formation of adhesions with extracellular matrix and activity of proteolytic enzymes or amoeboid, which is based on the increase in intracellular pressure caused by the enhancement of actin cortex contractility regulated by Rho-ROCK-MLCKII pathway, and does not depend on the formation of adhesive structures with the matrix, nor on the activity of proteases. The ability of tumor cells to switch from one motility mode to another depending on cell context and environmental conditions, termed migratory plasticity, contributes to the efficiency of dissemination and often allows the cells to avoid the applied treatment. The search for new therapeutic targets among cytoskeletal proteins offers an opportunity to directly influence cell migration. For successful treatment it is important to assess the likelihood of migratory plasticity in a particular tumor. Therefore, the search for specific markers that can indicate a high probability of migratory plasticity is very important.

FSCN1 Promotes Esophageal Carcinoma Progression Through Downregulating PTK6 via its RNA-Binding Protein Effect

Objective: Esophageal squamous cell carcinoma (ESCC) causes many deaths worldwide every year. Fascin actin-bundling protein 1(FSCN1) has been reported to be a promoter of ESCC via its actin-binding function, however, its new role as an RNA-binding protein (RBP) has not been investigated. Here, we explored the RBP role of FSCN1 in the development of ESCC. Methods: Whole-genome expression sequencing was performed to screen for altered genes after FSCN1 knockdown. RNA immunoprecipitation was performed to determine the target mRNA of FSCN1 as an RBP. In vitro experiments with ECA-109 and KYSE-150 and ex vivo experiments in tumor-bearing mice were performed to investigate the effects of FSCN1 and Protein Tyrosine Kinase 6 (PTK6) on ESCC progression. Results: FSCN1 could downregulate mRNA and the protein level of PTK6. The binding position of PTK6 (PTK6-T2) pre-mRNA to FSCN1 was determined. PTK6-T2 blocked the binding between FSCN1 and the pre-mRNA of PTK6, and thus reversed the promotion effect of FSCN1 on ESCC tumor progression via the AKT/GSK3β signaling pathway. Conclusion: A novel effect of FSCN1, RBP-binding with the pre-mRNA of PTK6, was confirmed to play an important role in ESCC progression. PTK6-T2, which is a specific inhibitor of FSCN1 binding to the pre-mRNA of PTK6, could impede the development of ESCC.

Recruitment of DNA to tumor-derived microvesicles

The shedding of extracellular vesicles (EVs) represents an important but understudied means of cell-cell communication in cancer. Among the currently described classes of EVs, tumor-derived microvesicles (TMVs) comprise a class of vesicles released directly from the cell surface. TMVs contain abundant cargo, including functional proteins and miRNA, which can be transferred to and alter the behavior of recipient cells. Here, we document that a fraction of extracellular double-stranded DNA (dsDNA) is enclosed within TMVs and protected from nuclease degradation. dsDNA inclusion in TMVs is regulated by ARF6 cycling and occurs with the cytosolic DNA sensor, cGAS, but independent of amphisome or micronuclei components. Our studies suggest that dsDNA is trafficked to TMVs via a mechanism distinct from the multivesicular body-dependent secretion reported for the extracellular release of cytosolic DNA. Furthermore, TMV dsDNA can be transferred to recipient cells with consequences to recipient cell behavior, reinforcing its relevance in mediating cell-cell communication.

Filopodium-derived vesicles produced by MIM enhance the migration of recipient cells

Extracellular vesicles (EVs) are classified as large EVs (l-EVs, or microvesicles) and small EVs (s-EVs, or exosomes). S-EVs are thought to be generated from endosomes through a process that mainly depends on the ESCRT protein complex, including ALG-2 interacting protein X (ALIX). However, the mechanisms of l-EV generation from the plasma membrane have not been identified. Membrane curvatures are generated by the bin-amphiphysin-rvs (BAR) family proteins, among which the inverse BAR (I-BAR) proteins are involved in filopodial protrusions. Here, we show that the I-BAR proteins, including missing in metastasis (MIM), generate l-EVs by scission of filopodia. Interestingly, MIM-containing l-EV production was promoted by in vivo equivalent external forces and by the suppression of ALIX, suggesting an alternative mechanism of vesicle formation to s-EVs. The MIM-dependent l-EVs contained lysophospholipids and proteins, including IRS4 and Rac1, which stimulated the migration of recipient cells through lamellipodia formation. Thus, these filopodia-dependent l-EVs, which we named as filopodia-derived vesicles (FDVs), modify cellular behavior.

Extracellular Vehicles of Oxygen-Depleted Mesenchymal Stromal Cells: Route to Off-Shelf Cellular Therapeutics?

Cellular therapy is a promising tool of human medicine to successfully treat complex and challenging pathologies such as cardiovascular diseases or chronic inflammatory conditions. Bone marrow-derived mesenchymal stromal cells (BMSCs) are in the limelight of these efforts, initially, trying to exploit their natural properties by direct transplantation. Extensive research on the therapeutic use of BMSCs shed light on a number of key aspects of BMSC physiology including the importance of oxygen in the control of BMSC phenotype. These efforts also led to a growing number of evidence indicating that the beneficial therapeutic effects of BMSCs can be mediated by BMSC-secreted agents. Further investigations revealed that BMSC-excreted extracellular vesicles could mediate the potentially therapeutic effects of BMSCs. Here, we review our current understanding of the relationship between low oxygen conditions and the effects of BMSC-secreted extracellular vesicles focusing on the possible medical relevance of this interplay.

Fascin actin-bundling protein 1 in human cancer: promising biomarker or therapeutic target?

Fascin actin-bundling protein 1 (FSCN1) is a highly conserved actin-bundling protein that cross links F-actin microfilaments into tight, parallel bundles. Elevated FSCN1 levels have been reported in many types of human cancers and have been correlated with aggressive clinical progression, poor prognosis, and survival outcomes. The overexpression of FSCN1 in cancer cells has been associated with tumor growth, migration, invasion, and metastasis. Currently, FSCN1 is recognized as a candidate biomarker for multiple cancer types and as a potential therapeutic target. The aim of this study was to provide a brief overview of the FSCN1 gene and protein structure and elucidate on its actin-bundling activity and physiological functions. The main focus was on the role of FSCN1 and its upregulatory mechanisms and significance in cancer cells. Up-to-date studies on FSCN1 as a novel biomarker and therapeutic target for human cancers are reviewed. It is shown that FSCN1 is an unusual biomarker and a potential therapeutic target for cancer.

Breaking Bad: Extracellular Vesicles Provoke Tumorigenic Responses Under Oxygen Deprivation

Intercellular communication is vital to tumor progression. In this issue of Developmental Cell, Bertolini et al. (2020) describe how small extracellular vesicles released from hypoxic mammary tumor cells facilitate intercellular communication, leading to alterations in mitochondrial dynamics and acquisition of invasive phenotypes in normal epithelial cells.

The ins and outs of microvesicles

Microvesicles are a heterogeneous group of membrane-enclosed vesicles that are released from cells into the extracellular space by the outward budding and pinching of the plasma membrane. These vesicles are loaded with multiple selectively sorted proteins and nucleic acids. Although interest in the clinical potential of microvesicles is increasing, there is only limited understanding of different types of microvesicles and the mechanisms involved in their formation. Here, we describe what is presently known about this expanding and complex field of research focusing on the mechanism of biogenesis, cargo loading, and release of microvesicles.

Mechanobiology of microvesicle release, uptake, and microvesicle-mediated activation

Microvesicles are small, membrane-bound vesicles that are shed from the plasma membrane of cells into the extracellular space. Microvesicles contain a variety of cargo not typically thought to be released from cells, including receptor tyrosine kinases, cytosolic signaling proteins, and microRNAs, which are transferred from donor cells to recipient cells. The transfer of microvesicle cargo can result in the transformation of recipient cells thereby supporting disease progression, including modified fibroblast metabolism, epithelial cell contractility, vascular remodeling, and immune cell inflammatory signaling. Additionally, microvesicles are believed to play prominent roles in cell-cell communication and disease progression as they are detected at elevated concentrations in diseased tissues. As microvesicle uptake by recipient cells can modulate cell function to promote disease progression, understanding the mechanisms and mechanosensitivity of microvesicle release, internalization, and the resulting signaling is crucial to fully comprehend their functions in disease. Here, we review recent advances in the understanding of actomyosin-regulated microvesicle biogenesis, microvesicle uptake via pinocytosis, and the resulting cellular transformation. We discuss the effects of altered cell contractility, mode of cell migration, and extracellular matrix compliance on microvesicle signaling, with direct implications in disease progression and identifying future therapeutic targets.

Extracellular Vesicles in the Tumor Microenvironment: Various Implications in Tumor Progression

Extracellular vesicle (EV) shedding is a biologically conserved cellular process across virtually every cell type. In cancer, EVs shed from tumor and stromal cells to the tumor microenvironment play a major role in determining tumor fate, which to a large extent is dictated by the biologically active cargo contained in EVs. Current understanding of various cancer-associated EVs has enabled the outlining of mechanistic connections between cargo and tumor-promoting functions. In this chapter, we describe examples of EV-mediated communication between tumor cells and stromal cells, highlighting the molecular constituents responsible for pro-tumorigenic effects. Furthermore, we discuss the roles of matrix-degrading EVs in cell invasion. Finally, we summarize research on the potential use of EVs as a novel approach to cancer therapeutics.

Tumor-derived extracellular vesicles: molecular parcels that enable regulation of the immune response in cancer

Extracellular vesicles (EVs) are a heterogeneous collection of membrane-bound vesicles released by cells that contain bioactive cargoes including proteins, lipids and nucleic acids. Multiple subpopulations of EVs have now been recognized and these include exosomes and microvesicles. EVs have been thought to facilitate intercellular and distal communication to bring about various processes that enable tumor progression and metastases. Here, we describe the current knowledge of the functional cargo contained within EVs, with a focus on tumor microvesicles, and review the emerging theory of how EVs support immune suppression in cancer.

An ARF6-Exportin-5 axis delivers pre-miRNA cargo to tumour microvesicles

Tumor-derived microvesicles (TMVs) comprise a class of extracellular vesicles released from tumor cells that are now understood to facilitate communication between the tumor and the surrounding microenvironment. Despite their significance, the regulatory mechanisms governing the trafficking of bioactive cargos to TMVs at the cell surface remain poorly defined. Here we describe a molecular pathway for the delivery of microRNA (miRNA) cargo to nascent TMVs involving the dissociation of a pre-miRNA/Exportin-5 complex from Ran-GTP following nuclear export, and its subsequent transfer to a cytoplasmic shuttle comprised of ARF6-GTP and GRP1. As such, ARF6 activation increases pre-miRNA cargo contained within TMVs via a process that requires casein kinase 2-mediated phosphorylation of Ran-GAP1. Further, TMVs were found to contain pre-miRNA processing machinery including Dicer and Argonaute 2, which allow for cell-free pre-miRNA processing within shed vesicles. These findings offer cellular targets to block the loading and processing of pre-miRNAs within TMVs.