Bone vascular niche E-selectin induces mesenchymal-epithelial transition and Wnt activation in cancer cells to promote bone metastasis

Navigating the biophysical landscape: how physical cues steer the journey of bone metastatic tumor cells

Many tumors prefer to metastasize to bone, but the underlying mechanisms remain elusive. The human skeletal system has unique physical properties, that are distinct from other organs, which play a key role in directing the behavior of tumor cells within bone. Understanding the physical journey of tumor cells within bone is crucial. In this review we discuss bone metastasis in the context of how physical cues in the bone vasculature and bone marrow niche regulate the fate of tumor cells. Our objective is to inspire innovative diagnostic and therapeutic approaches for bone metastasis from a mechanobiological perspective.

Immune mediated support of metastasis: Implication for bone invasion

Bone is a common organ affected by metastasis in various advanced cancers, including lung, breast, prostate, colorectal, and melanoma. Once a patient is diagnosed with bone metastasis, the patient's quality of life and overall survival are significantly reduced owing to a wide range of morbidities and the increasing difficulty of treatment. Many studies have shown that bone metastasis is closely related to bone microenvironment, especially bone immune microenvironment. However, the effects of various immune cells in the bone microenvironment on bone metastasis remain unclear. Here, we described the changes in various immune cells during bone metastasis and discussed their related mechanisms. Osteoblasts, adipocytes, and other non-immune cells closely related to bone metastasis were also included. This review also summarized the existing treatment methods and potential therapeutic targets, and provided insights for future studies of cancer bone metastasis.

Vitacrystallography: Structural Biomarkers of Breast Cancer Obtained by X-ray Scattering

With breast cancer being one of the most widespread causes of death for women, there is an unmet need for its early detection. For this purpose, we propose a non-invasive approach based on X-ray scattering. We measured samples from 107 unique patients provided by the Breast Cancer Now Tissue Biobank, with the total dataset containing 2958 entries. Two different sample-to-detector distances, 2 and 16 cm, were used to access various structural biomarkers at distinct ranges of momentum transfer values. The biomarkers related to lipid metabolism are consistent with those of previous studies. Machine learning analysis based on the Random Forest Classifier demonstrates excellent performance metrics for cancer/non-cancer binary decisions. The best sensitivity and specificity values are 80% and 92%, respectively, for the sample-to-detector distance of 2 cm and 86% and 83% for the sample-to-detector distance of 16 cm.

Metabolic Signaling in Cancer Metastasis

Metastases, which are the leading cause of death in patients with cancer, have metabolic vulnerabilities. Alterations in metabolism fuel the energy and biosynthetic needs of metastases but are also needed to activate cell state switches in cells leading to invasion, migration, colonization, and outgrowth in distant organs. Specifically, metabolites can activate protein kinases as well as receptors and they are crucial substrates for posttranslational modifications on histone and nonhistone proteins. Moreover, metabolic enzymes can have moonlighting functions by acting catalytically, mainly as protein kinases, or noncatalytically through protein-protein interactions. Here, we summarize the current knowledge on metabolic signaling in cancer metastasis.

SIGNIFICANCE

Effective drugs for the prevention and treatment of metastases will have an immediate impact on patient survival. To overcome the current lack of such drugs, a better understanding of the molecular processes that are an Achilles heel in metastasizing cancer cells is needed. One emerging opportunity is the metabolic changes cancer cells need to undergo to successfully metastasize and grow in distant organs. Mechanistically, these metabolic changes not only fulfill energy and biomass demands, which are often in common between cancer and normal but fast proliferating cells, but also metabolic signaling which enables the cell state changes that are particularly important for the metastasizing cancer cells.

Combining 5-azacitidine with the E-selectin antagonist uproleselan is an effective strategy to augment responses in myelodysplasia and acute myeloid leukaemia

The interaction of acute myeloid leukaemic (AML) blasts with the bone marrow (BM) microenvironment is a major determinant governing disease progression and resistance to treatment. The constitutive expression of E-selectin in the vascular compartment of BM, a key endothelial cell factor, directly mediates chemoresistance via E-selectin ligand/receptors. Despite the success of hypomethylating agent (HMA)-containing regimens to induce remissions in older AML patients, the development of primary or secondary resistance is common. We report that following treatment with 5-azacitidine, promoter regions regulating the biosynthesis of the E-selectin ligands, sialyl Lewis X, become further hypomethylated. The resultant upregulation of these gene products, in particular α(1,3)-fucosyltransferase VII (FUT7) and α(2,3)-sialyltransferase IV (ST3GAL4), likely causes functional E-selectin binding. When combined with the E-selectin antagonist uproleselan, the adhesion to E-selectin is reversed and the survival of mice transplanted with AML cells is prolonged. Finally, we present clinical evidence showing that BM myeloid cells from higher risk MDS and AML patients have the potential to bind E-selectin, and these cells are more abundant in 5-azacitidine-non-responsive patients. The collective data provide a strong rationale to evaluate 5-azacitidine in combination with the E-selectin antagonist, uproleselan, in this patient population.

Unravelling the Mysteries of the Sonic Hedgehog Pathway in Cancer Stem Cells: Activity, Crosstalk and Regulation

The Sonic Hedgehog (Shh) signalling pathway plays a critical role in normal development and tissue homeostasis, guiding cell differentiation, proliferation, and survival. Aberrant activation of this pathway, however, has been implicated in the pathogenesis of various cancers, largely due to its role in regulating cancer stem cells (CSCs). CSCs are a subpopulation of cancer cells with the ability to self-renew, differentiate, and initiate tumour growth, contributing significantly to tumorigenesis, recurrence, and resistance to therapy. This review focuses on the intricate activity of the Shh pathway within the context of CSCs, detailing the molecular mechanisms through which Shh signalling influences CSC properties, including self-renewal, differentiation, and survival. It further explores the regulatory crosstalk between the Shh pathway and other signalling pathways in CSCs, highlighting the complexity of this regulatory network. Here, we delve into the upstream regulators and downstream effectors that modulate Shh pathway activity in CSCs. This review aims to cast a specific focus on the role of the Shh pathway in CSCs, provide a detailed exploration of molecular mechanisms and regulatory crosstalk, and discuss current and developing inhibitors. By summarising key findings and insights gained, we wish to emphasise the importance of further elucidating the interplay between the Shh pathway and CSCs to develop more effective cancer therapies.

Molecular landscape of prostate cancer bone metastasis

Prostate cancer (PC) has a high propensity to develop bone metastases, causing severe pain and pathological fractures that profoundly impact a patients' normal functions. Current clinical intervention is mainly palliative focused on pain management, and tumor progression is refractory to standard therapeutic regimens. This limited treatment efficacy is at least partially due to a lack of comprehensive understanding of the molecular landscape of the disease pathology, along with the intensive overlapping of physiological and pathological molecular signaling. The niche is overwhelmed with diverse cell types with inter- and intra-heterogeneity, along with growth factor-enriched cells that are supportive of invading cell proliferation, providing an additional layer of complexity. This review seeks to provide molecular insights into mechanisms underlying PC bone metastasis development and progression.

Unbiased metastatic niche-labeling identifies estrogen receptor-positive macrophages as a barrier of T cell infiltration during bone colonization

Microenvironment niches determine cellular fates of metastatic cancer cells. However, robust and unbiased approaches to identify niche components and their molecular profiles are lacking. We established Sortase A-Based Microenvironment Niche Tagging (SAMENT), which selectively labels cells encountered by cancer cells during metastatic colonization. SAMENT was applied to multiple cancer models colonizing the same organ and the same cancer to different organs. Common metastatic niche features include macrophage enrichment and T cell depletion. Macrophage niches are phenotypically diverse between different organs. In bone, macrophages express the estrogen receptor alpha (ERα) and exhibit active ERα signaling in male and female hosts. Conditional knockout of Esr1 in macrophages significantly retarded bone colonization by allowing T cell infiltration. ERα expression was also discovered in human bone metastases of both genders. Collectively, we identified a unique population of ERα+ macrophages in the metastatic niche and functionally tied ERα signaling in macrophages to T cell exclusion during metastatic colonization.

HIGHLIGHTS

SAMENT is a robust metastatic niche-labeling approach amenable to single-cell omics.Metastatic niches are typically enriched with macrophages and depleted of T cells.Direct interaction with cancer cells induces ERα expression in niche macrophages. Knockout of Esr1 in macrophages allows T cell infiltration and retards bone colonization.

Phenotypic plasticity - Implications for tumours in bone

Metastasis is a major contributor to cancer patient mortality. Tumour cells often develop phenotypic plasticity to successfully metastasize to different target organs. Recent progress in the study of bone metastasis has provided novel insight into the biological processes that drive the spread and growth of cancer cells in the bone. In this review, we provide a summary of how the bone marrow microenvironment promotes phenotypic plasticity of metastatic tumour cells and alters therapeutic responses. We highlight pivotal transformations in cellular status driven by plasticity, including mesenchymal-epithelial transition, acquisition of stem-like traits, and awakening from dormancy. Additionally, we describe the phenomenon of host-organ mimicry and metabolic rewiring that collectively serve as key attributes of disseminated tumour cells, enabling their successful colonization and growth within the bone marrow microenvironment.

MiR-200c reprograms fibroblasts to recapitulate the phenotype of CAFs in breast cancer progression

Mesenchymal-epithelial plasticity driving cancer progression in cancer-associated fibroblasts (CAFs) is undetermined. This work identifies a subgroup of CAFs in human breast cancer exhibiting mesenchymal-to-epithelial transition (MET) or epithelial-like profile with high miR-200c expression. MiR-200c overexpression in fibroblasts is sufficient to drive breast cancer aggressiveness. Oxidative stress in the tumor microenvironment induces miR-200c by DNA demethylation. Proteomics, RNA-seq and functional analyses reveal that miR-200c is a novel positive regulator of NFκB-HIF signaling via COMMD1 downregulation and stimulates pro-tumorigenic inflammation and glycolysis. Reprogramming fibroblasts toward MET via miR-200c reduces stemness and induces a senescent phenotype. This pro-tumorigenic profile in CAFs fosters carcinoma cell resistance to apoptosis, proliferation and immunosuppression, leading to primary tumor growth, metastases, and resistance to immuno-chemotherapy. Conversely, miR-200c inhibition in fibroblasts restrains tumor growth with abated oxidative stress and an anti-tumorigenic immune environment. This work determines the mechanisms by which MET in CAFs via miR-200c transcriptional enrichment with DNA demethylation triggered by oxidative stress promotes cancer progression. CAFs undergoing MET trans-differentiation and senescence coordinate heterotypic signaling that may be targeted as an anti-cancer strategy.

Stress in the metastatic journey - the role of cell communication and clustering in breast cancer progression and treatment resistance

Breast cancer stands as the most prevalent malignancy afflicting women. Despite significant advancements in its diagnosis and treatment, breast cancer metastasis continues to be a leading cause of mortality among women. To metastasize, cancer cells face numerous challenges: breaking away from the primary tumor, surviving in the circulation, establishing in a distant location, evading immune detection and, finally, thriving to initiate a new tumor. Each of these sequential steps requires cancer cells to adapt to a myriad of stressors and develop survival mechanisms. In addition, most patients with breast cancer undergo surgical removal of their primary tumor and have various therapeutic interventions designed to eradicate cancer cells. Despite this plethora of attacks and stresses, certain cancer cells not only manage to persist but also proliferate robustly, giving rise to substantial tumors that frequently culminate in the patient's demise. To enhance patient outcomes, there is an imperative need for a deeper understanding of the molecular and cellular mechanisms that empower cancer cells to not only survive but also expand. Herein, we delve into the intrinsic stresses that cancer cells encounter throughout the metastatic journey and the additional stresses induced by therapeutic interventions. We focus on elucidating the remarkable strategies adopted by cancer cells, such as cell-cell clustering and intricate cell-cell communication mechanisms, to ensure their survival.

The role of N-glycosylation in cancer

Despite advances in understanding the development and progression of cancer in recent years, there remains a lack of comprehensive characterization of the cancer glycoproteome. Glycoproteins play an important role in medicine and are involved in various human disease conditions including cancer. Glycan-moieties participate in fundamental cancer processes like cell signaling, invasion, angiogenesis, and metastasis. Aberrant N-glycosylation significantly impacts cancer processes and targeted therapies in clinic. Therefore, understanding N-glycosylation in a tumor is essential for comprehending disease progression and discovering anti-cancer targets and biomarkers for therapy monitoring and diagnosis. This review presents the fundamental process of protein N-glycosylation and summarizes glycosylation changes in tumor cells, including increased terminal sialylation, N-glycan branching, and core-fucosylation. Also, the role of N-glycosylation in tumor signaling pathways, migration, and metabolism are discussed. Glycoproteins and glycopeptides as potential biomarkers for early detection of cancer based on site specificity have been introduced. Collectively, understanding and exploring the cancer glycoproteome, along with its role in medicine, implication in cancer and other human diseases, highlights the significance of N-glycosylation in tumor processes, necessitating further research for potential anti-cancer targets and biomarkers.

PTH and the Regulation of Mesenchymal Cells within the Bone Marrow Niche

Parathyroid hormone (PTH) plays a pivotal role in maintaining calcium homeostasis, largely by modulating bone remodeling processes. Its effects on bone are notably dependent on the duration and frequency of exposure. Specifically, PTH can initiate both bone formation and resorption, with the outcome being influenced by the manner of PTH administration: continuous or intermittent. In continuous administration, PTH tends to promote bone resorption, possibly by regulating certain genes within bone cells. Conversely, intermittent exposure generally favors bone formation, possibly through transient gene activation. PTH's role extends to various aspects of bone cell activity. It directly influences skeletal stem cells, osteoblastic lineage cells, osteocytes, and T cells, playing a critical role in bone generation. Simultaneously, it indirectly affects osteoclast precursor cells and osteoclasts, and has a direct impact on T cells, contributing to its role in bone resorption. Despite these insights, the intricate mechanisms through which PTH acts within the bone marrow niche are not entirely understood. This article reviews the dual roles of PTH-catabolic and anabolic-on bone cells, highlighting the cellular and molecular pathways involved in these processes. The complex interplay of these factors in bone remodeling underscores the need for further investigation to fully comprehend PTH's multifaceted influence on bone health.

Phenotypic Heterogeneity, Bidirectionality, Universal Cues, Plasticity, Mechanics, and the Tumor Microenvironment Drive Cancer Metastasis

Tumor diseases become a huge problem when they embark on a path that advances to malignancy, such as the process of metastasis. Cancer metastasis has been thoroughly investigated from a biological perspective in the past, whereas it has still been less explored from a physical perspective. Until now, the intraluminal pathway of cancer metastasis has received the most attention, while the interaction of cancer cells with macrophages has received little attention. Apart from the biochemical characteristics, tumor treatments also rely on the tumor microenvironment, which is recognized to be immunosuppressive and, as has recently been found, mechanically stimulates cancer cells and thus alters their functions. The review article highlights the interaction of cancer cells with other cells in the vascular metastatic route and discusses the impact of this intercellular interplay on the mechanical characteristics and subsequently on the functionality of cancer cells. For instance, macrophages can guide cancer cells on their intravascular route of cancer metastasis, whereby they can help to circumvent the adverse conditions within blood or lymphatic vessels. Macrophages induce microchannel tunneling that can possibly avoid mechanical forces during extra- and intravasation and reduce the forces within the vascular lumen due to vascular flow. The review article highlights the vascular route of cancer metastasis and discusses the key players in this traditional route. Moreover, the effects of flows during the process of metastasis are presented, and the effects of the microenvironment, such as mechanical influences, are characterized. Finally, the increased knowledge of cancer metastasis opens up new perspectives for cancer treatment.

How important is EMT for cancer metastasis?

Epithelial-to-mesenchymal transition (EMT), a biological phenomenon of cellular plasticity initially reported in embryonic development, has been increasingly recognized for its importance in cancer progression and metastasis. Despite tremendous progress being made in the past 2 decades in our understanding of the molecular mechanism and functional importance of EMT in cancer, there are several mysteries around EMT that remain unresolved. In this Unsolved Mystery, we focus on the variety of EMT types in metastasis, cooperative and collective EMT behaviors, spatiotemporal characterization of EMT, and strategies of therapeutically targeting EMT. We also highlight new technical advances that will facilitate the efforts to elucidate the unsolved mysteries of EMT in metastasis.

Update on Epithelial-Mesenchymal Plasticity in Cancer Progression

Epithelial-mesenchymal transition (EMT) is a cellular process by which epithelial cells lose their characteristics and acquire mesenchymal traits to promote cell movement. This program is aberrantly activated in human cancers and endows tumor cells with increased abilities in tumor initiation, cell migration, invasion, metastasis, and therapy resistance. The EMT program in tumors is rarely binary and often leads to a series of gradual or intermediate epithelial-mesenchymal states. Functionally, epithelial-mesenchymal plasticity (EMP) improves the fitness of cancer cells during tumor progression and in response to therapies. Here, we discuss the most recent advances in our understanding of the diverse roles of EMP in tumor initiation, progression, metastasis, and therapy resistance and address major clinical challenges due to EMP-driven phenotypic heterogeneity in cancer. Uncovering novel molecular markers and key regulators of EMP in cancer will aid the development of new therapeutic strategies to prevent cancer recurrence and overcome therapy resistance.

Preparation of genetically or chemically engineered exosomes and their therapeutic effects in bone regeneration and anti-inflammation

The treatment of bone or cartilage damage and inflammation-related diseases has been a long-standing research hotspot. Traditional treatments such as surgery and cell therapy have only displayed limited efficacy because they can't avoid potential deterioration and ensure cell activity. Recently, exosomes have become a favorable tool for various tissue reconstruction due to their abundant content of proteins, lipids, DNA, RNA and other substances, which can promote bone regeneration through osteogenesis, angiogenesis and inflammation modulation. Besides, exosomes are also promising delivery systems because of stability in the bloodstream, immune stealth capacity, intrinsic cell-targeting property and outstanding intracellular communication. Despite having great potential in therapeutic delivery, exosomes still show some limitations in clinical studies, such as inefficient targeting ability, low yield and unsatisfactory therapeutic effects. In order to overcome the shortcomings, increasing studies have prepared genetically or chemically engineered exosomes to improve their properties. This review focuses on different methods of preparing genetically or chemically engineered exosomes and the therapeutic effects of engineering exosomes in bone regeneration and anti-inflammation, thereby providing some references for future applications of engineering exosomes.

A Ubiquitin-Dependent Switch on MEF2D Senses Pro-Metastatic Niche Signals to Facilitate Intrahepatic Metastasis of Liver Cancer

Effective treatment for metastasis, a leading cause of cancer-associated death, is still lacking. To seed on a distal organ, disseminated cancer cells (DCCs) must adapt to the local tissue microenvironment. However, it remains elusive how DCCs respond the pro-metastatic niche signals. Here, systemic motif-enrichment identified myocyte enhancer factor 2D (MEF2D) as a critical sensor of niche signals to regulate DCCs adhesion and colonization, leading to intrahepatic metastasis and recurrence of liver cancer. In this context, MEF2D transactivates Itgb1 (coding β1-integrin) and Itgb4 (coding β4-integrin) to execute temporally unique functions, where ITGB1 recognizes extracellular matrix for early seeding, and ITGB4 acts as a novel sensor of neutrophil extracellular traps-DNA (NETs-DNA) for subsequent chemotaxis and colonization. In turn, an integrin-FAK circuit promotes a phosphorylation-dependent USP14-orchastrated deubiquitination switch to stabilize MEF2D via circumventing degradation by the E3-ubiquitin-ligase MDM2. Clinically, the USP14(pS432)-MEF2D-ITGB1/4 feedback loop is often hyper-active and indicative of inferior outcomes in human malignancies, while its blockade abrogated intrahepatic metastasis of DCCs. Together, DCCs exploit a deubiquitination-dependent switch on MEF2D to integrate niche signals in the liver mesenchyme, thereby amplifying the pro-metastatic integrin-FAK signaling. Disruption of this feedback loop is clinically applicable with fast-track potential to block microenvironmental cues driving metastasis.

Mechanisms of Organ-Specific Metastasis of Breast Cancer

Cancer metastasis, or the development of secondary tumors in distant tissues, accounts for the vast majority of fatalities in patients with breast cancer. Breast cancer cells show a striking proclivity to metastasize to distinct organs, specifically the lung, liver, bone, and brain, where they face unique environmental pressures and a wide variety of tissue-resident cells that together create a strong barrier for tumor survival and growth. As a consequence, successful metastatic colonization is critically dependent on reciprocal cross talk between cancer cells and host cells within the target organ, a relationship that shapes the formation of a tumor-supportive microenvironment. Here, we discuss the mechanisms governing organ-specific metastasis in breast cancer, focusing on the intricate interactions between metastatic cells and specific niche cells within a secondary organ, and the remarkable adaptations of both compartments that cooperatively support cancer growth. More broadly, we aim to provide a framework for the microenvironmental prerequisites within each distinct metastatic site for successful breast cancer metastatic seeding and outgrowth.

Glycobiology in osteoclast differentiation and function

Glycans, either alone or in complex with glycan-binding proteins, are essential structures that can regulate cell biology by mediating protein stability or receptor dimerization under physiological and pathological conditions. Certain glycans are ligands for lectins, which are carbohydrate-specific receptors. Bone is a complex tissue that provides mechanical support for muscles and joints, and the regulation of bone mass in mammals is governed by complex interplay between bone-forming cells, called osteoblasts, and bone-resorbing cells, called osteoclasts. Bone erosion occurs when bone resorption notably exceeds bone formation. Osteoclasts may be activated during cancer, leading to a range of symptoms, including bone pain, fracture, and spinal cord compression. Our understanding of the role of protein glycosylation in cells and tissues involved in osteoclastogenesis suggests that glycosylation-based treatments can be used in the management of diseases. The aims of this review are to clarify the process of bone resorption and investigate the signaling pathways mediated by glycosylation and their roles in osteoclast biology. Moreover, we aim to outline how the lessons learned about these approaches are paving the way for future glycobiology-focused therapeutics.

Control of TGFβ signalling by ubiquitination independent function of E3 ubiquitin ligase TRIP12

Transforming growth factor β (TGFβ) pathway is a master regulator of cell proliferation, differentiation, and death. Deregulation of TGFβ signalling is well established in several human diseases including autoimmune disorders and cancer. Thus, understanding molecular pathways governing TGFβ signalling may help better understand the underlying causes of some of those conditions. Here, we show that a HECT domain E3 ubiquitin ligase TRIP12 controls TGFβ signalling in multiple models. Interestingly, TRIP12 control of TGFβ signalling is completely independent of its E3 ubiquitin ligase activity. Instead, TRIP12 recruits SMURF2 to SMAD4, which is most likely responsible for inhibitory monoubiquitination of SMAD4, since SMAD4 monoubiquitination and its interaction with SMURF2 were dramatically downregulated in TRIP12-/- cells. Additionally, genetic inhibition of TRIP12 in human and murine cells leads to robust activation of TGFβ signalling which was rescued by re-introducing wildtype TRIP12 or a catalytically inactive C1959A mutant. Importantly, TRIP12 control of TGFβ signalling is evolutionary conserved. Indeed, genetic inhibition of Drosophila TRIP12 orthologue, ctrip, in gut leads to a reduced number of intestinal stem cells which was compensated by the increase in differentiated enteroendocrine cells. These effects were completely normalised in Drosophila strain where ctrip was co-inhibited together with Drosophila SMAD4 orthologue, Medea. Similarly, in murine 3D intestinal organoids, CRISPR/Cas9 mediated genetic targeting of Trip12 enhances TGFβ mediated proliferation arrest and cell death. Finally, CRISPR/Cas9 mediated genetic targeting of TRIP12 in MDA-MB-231 breast cancer cells enhances the TGFβ induced migratory capacity of these cells which was rescued to the wildtype level by re-introducing wildtype TRIP12. Our work establishes TRIP12 as an evolutionary conserved modulator of TGFβ signalling in health and disease.

Bone marrow vasculature advanced in vitro models for cancer and cardiovascular research

Cardiometabolic diseases and cancer are among the most common diseases worldwide and are a serious concern to the healthcare system. These conditions, apparently distant, share common molecular and cellular determinants, that can represent targets for preventive and therapeutic approaches. The bone marrow plays an important role in this context as it is the main source of cells involved in cardiovascular regeneration, and one of the main sites of liquid and solid tumor metastasis, both characterized by the cellular trafficking across the bone marrow vasculature. The bone marrow vasculature has been widely studied in animal models, however, it is clear the need for human-specific in vitro models, that resemble the bone vasculature lined by endothelial cells to study the molecular mechanisms governing cell trafficking. In this review, we summarized the current knowledge on in vitro models of bone marrow vasculature developed for cardiovascular and cancer research.

Identification of potential classes of glycoligands mediating dynamic endothelial adhesion of human tumor cells

One critical step of metastasis formation is the extravasation of circulating tumor cells from the bloodstream. This process requires the dynamic interaction of cell adhesion molecules like E-selectin on endothelial cells with carbohydrate ligands on tumor cells. To characterize these glycans in a comprehensible approach, the rolling, tethering, and firm adhesion of nine human tumor cell lines on human umbilical vein endothelial cells was analyzed using laminar flow adhesion assays. The tumor cell lines were grouped into three subsets by their canonical E-selectin ligand status (sialyl-Lewis A and X +/+, -/+, -/-) and their adhesiveness was compared after enzymatic, pharmacologic, chemical treatment or antibody blockade of the tumor cells or endothelial cells, respectively. Tumor cells were also screened regarding their glycosyltransferase expression profile. We found that although E-selectin and terminal α2,3-sialic acid largely determined firm adhesion, adhesive events did not exclusively depend on the presence of sialyl-Lewis A and/or sialyl-Lewis X. Nevertheless, two of the three sialyl-Lewis A/X-/- tumor cells additionally or fully depended on vascular cell adhesion molecule-1 for firm adhesion. The significance of O-GalNAc- and N-glycans for adhesion varied remarkably among the tumor cells. The sialyl-Lewis A/X+/+ subset showed glycoprotein-independent adhesion, suggesting a role of glycolipids as well. All sialyl-Lewis A/X-/- tumor cells lacked FUT3 and FUT7 expression as opposed to sialyl-Lewis A/X+/+ or -/+ cell lines. In summary, the glycans on tumor cells mediating endothelial adhesion are not as much restricted to sialyl-Lewis A /X as previously assumed. The present study specifically suggests α2,3-linked sialic acid, O-GalNAc glycans, glycosphingolipids, and FUT3/FUT7 products as promising targets for future studies.

Cancer cell plasticity during tumor progression, metastasis and response to therapy

Cell plasticity represents the ability of cells to be reprogrammed and to change their fate and identity, enabling homeostasis restoration and tissue regeneration following damage. Cell plasticity also contributes to pathological conditions, such as cancer, enabling cells to acquire new phenotypic and functional features by transiting across distinct cell states that contribute to tumor initiation, progression, metastasis and resistance to therapy. Here, we review the intrinsic and extrinsic mechanisms driving cell plasticity that promote tumor growth and proliferation as well as metastasis and drug tolerance. Finally, we discuss how cell plasticity could be exploited for anti-cancer therapy.

Awakening of Dormant Breast Cancer Cells in the Bone Marrow

Up to 40% of patients with breast cancer (BC) have metastatic cells in the bone marrow (BM) at the initial diagnosis of localized disease. Despite definitive systemic adjuvant therapy, these cells survive in the BM microenvironment, enter a dormant state and recur stochastically for more than 20 years. Once they begin to proliferate, recurrent macrometastases are not curable, and patients generally succumb to their disease. Many potential mechanisms for initiating recurrence have been proposed, but no definitive predictive data have been generated. This manuscript reviews the proposed mechanisms that maintain BC cell dormancy in the BM microenvironment and discusses the data supporting specific mechanisms for recurrence. It addresses the well-described mechanisms of secretory senescence, inflammation, aging, adipogenic BM conversion, autophagy, systemic effects of trauma and surgery, sympathetic signaling, transient angiogenic bursts, hypercoagulable states, osteoclast activation, and epigenetic modifications of dormant cells. This review addresses proposed approaches for either eliminating micrometastases or maintaining a dormant state.

Insights into the metastatic cascade through research autopsies

Metastasis is a complex process and the leading cause of cancer-related death globally. Recent studies have demonstrated that genomic sequencing data from paired primary and metastatic tumours can be used to trace the evolutionary origins of cells responsible for metastasis. This approach has yielded new insights into the genomic alterations that engender metastatic potential, and the mechanisms by which cancer spreads. Given that the reliability of these approaches is contingent upon how representative the samples are of primary and metastatic tumour heterogeneity, we review insights from studies that have reconstructed the evolution of metastasis within the context of their cohorts and designs. We discuss the role of research autopsies in achieving the comprehensive sampling necessary to advance the current understanding of metastasis.

Recent progress in nanocarrier-based drug delivery systems for antitumour metastasis

Tumour metastasis is one of the major factors leading to poor prognosis as well as lower survival among cancer patients. A number of studies investigating the inhibition of tumour metastasis have been conducted. It is difficult to achieve satisfactory results with surgery alone for distant metastatic tumours, and chemotherapy can boost the healing rate and prognosis of patients. However, the poor therapeutic efficacy of chemotherapy drugs due to their low solubility, lack of tumour targeting, instability in vivo, high toxicity and multidrug resistance hinder their application. Immunotherapy is beneficial to the treatment of metastatic cancers, but it also has disadvantages such as adverse reactions and acquired resistance. Fortunately, delivery of chemotherapeutic drugs with nanocarriers can reduce systemic reactions caused by chemotherapeutic agents and inhibit metastasis. This review discusses the underlying mechanisms of metastasis, therapeutic approaches for antitumour metastasis, the advantages of nanodrug delivery systems and their application in reducing metastasis.

Tumor cell plasticity in targeted therapy-induced resistance: mechanisms and new strategies

Despite the success of targeted therapies in cancer treatment, therapy-induced resistance remains a major obstacle to a complete cure. Tumor cells evade treatments and relapse via phenotypic switching driven by intrinsic or induced cell plasticity. Several reversible mechanisms have been proposed to circumvent tumor cell plasticity, including epigenetic modifications, regulation of transcription factors, activation or suppression of key signaling pathways, as well as modification of the tumor environment. Epithelial-to-mesenchymal transition, tumor cell and cancer stem cell formation also serve as roads towards tumor cell plasticity. Corresponding treatment strategies have recently been developed that either target plasticity-related mechanisms or employ combination treatments. In this review, we delineate the formation of tumor cell plasticity and its manipulation of tumor evasion from targeted therapy. We discuss the non-genetic mechanisms of targeted drug-induced tumor cell plasticity in various types of tumors and provide insights into the contribution of tumor cell plasticity to acquired drug resistance. New therapeutic strategies such as inhibition or reversal of tumor cell plasticity are also presented. We also discuss the multitude of clinical trials that are ongoing worldwide with the intention of improving clinical outcomes. These advances provide a direction for developing novel therapeutic strategies and combination therapy regimens that target tumor cell plasticity.

Cellular Senescence, a Novel Area of Investigation for Metastatic Diseases

Metastasis is a systemic condition and the major challenge among cancer types, as it can lead to multiorgan vulnerability. Recently, attention has been drawn to cellular senescence, a complex stress response condition, as a factor implicated in metastatic dissemination and outgrowth. Here, we examine the current knowledge of the features required for cells to invade and colonize secondary organs and how senescent cells can contribute to this process. First, we describe the role of senescence in placentation, itself an invasive process which has been linked to higher rates of invasive cancers. Second, we describe how senescent cells can contribute to metastatic dissemination and colonization. Third, we discuss several metabolic adaptations by which senescent cells could promote cancer survival along the metastatic journey. In conclusion, we posit that targeting cellular senescence may have a potential therapeutic efficacy to limit metastasis formation.

Metastasis prevention: How to catch metastatic seeds

Despite considerable advances in the evolution of anticancer therapies, metastasis still remains the main cause of cancer mortality. Therefore, current strategies for cancer cure should be redirected towards prevention of metastasis. Targeting metastatic pathways represents a promising therapeutic opportunity aimed at obstructing tumor cell dissemination and metastatic colonization. In this review, we focus on preclinical studies and clinical trials over the last five years that showed high efficacy in suppressing metastasis through targeting lymph node dissemination, tumor cell extravasation, reactive oxygen species, pre-metastatic niche, exosome machinery, and dormancy.

Bone Metastasis Initiation Is Coupled with Bone Remodeling through Osteogenic Differentiation of NG2+ Cells

The bone microenvironment is dynamic and undergoes remodeling in normal and pathologic conditions. Whether such remodeling affects disseminated tumor cells (DTC) and bone metastasis remains poorly understood. Here, we demonstrated that pathologic fractures increase metastatic colonization around the injury. NG2+ cells are a common participant in bone metastasis initiation and bone remodeling in both homeostatic and fractured conditions. NG2+ bone mesenchymal stem/stromal cells (BMSC) often colocalize with DTCs in the perivascular niche. Both DTCs and NG2+ BMSCs are recruited to remodeling sites. Ablation of NG2+ lineage impaired bone remodeling and concurrently diminished metastatic colonization. In cocultures, NG2+ BMSCs, especially when undergoing osteodifferentiation, enhanced cancer cell proliferation and migration. Knockout of N-cadherin in NG2+ cells abolished these effects in vitro and phenocopied NG2+ lineage depletion in vivo. These findings uncover dual roles of NG2+ cells in metastasis and remodeling and indicate that osteodifferentiation of BMSCs promotes metastasis initiation via N-cadherin-mediated cell-cell interaction.

SIGNIFICANCE

The bone colonization of cancer cells occurs in an environment that undergoes constant remodeling. Our study provides mechanistic insights into how bone homeostasis and pathologic repair lead to the outgrowth of disseminated cancer cells, thereby opening new directions for further etiologic and epidemiologic studies of tumor recurrences. This article is highlighted in the In This Issue feature, p. 247.

Meso-Hannokinol inhibits breast cancer bone metastasis via the ROS/JNK/ZEB1 axis

Distal metastases from breast cancer, especially bone metastases, are extremely common in the late stages of the disease and are associated with a poor prognosis. EMT is a biomarker of the early process of bone metastasis, and MMP-9 and MMP-13 are important osteoclastic activators. Previously, we found that meso-Hannokinol (HA) could significantly inhibit EMT and MMP-9 and MMP-13 expressions in breast cancer cells. On this basis, we further explored the role of HA in breast cancer bone metastasis. In vivo, we established a breast cancer bone metastasis model by intracardially injecting breast cancer cells. Intraperitoneal injections of HA significantly reduced breast cancer cell metastasis to the leg bone in mice and osteolytic lesions caused by breast cancer. In vitro, HA inhibited the migration and invasion of breast cancer cells and suppressed the expressions of EMT, MMP-9, MMP-13, and other osteoclastic activators. HA inhibited EMT and MMP-9 by activating the ROS/JNK pathway as demonstrated by siJNK and SP600125 inhibition of JNK phosphorylation and NAC scavenging of ROS accumulation. Moreover, HA promoted bone formation and inhibited bone resorption in vitro. In conclusion, our findings suggest that HA may be an excellent candidate for treating breast cancer bone metastasis.

Intravital imaging of Wnt/β-catenin and ATF2-dependent signalling pathways during tumour cell invasion and metastasis

Wnt signalling has been implicated as a driver of tumour cell metastasis, but less is known about which branches of Wnt signalling are involved and when they act in the metastatic cascade. Here, using a unique intravital imaging platform and fluorescent reporters, we visualised β-catenin/TCF-dependent and ATF2-dependent signalling activities during human cancer cell invasion, intravasation and metastatic lesion formation in the chick embryo host. We found that cancer cells readily shifted between states of low and high canonical Wnt activity. Cancer cells that displayed low Wnt canonical activity showed higher invasion and intravasation potential in primary tumours and in metastatic lesions. In contrast, cancer cells showing low ATF2-dependent activity were significantly less invasive both at the front of primary tumours and in metastatic lesions. Simultaneous visualisation of both these reporters using a double-reporter cell line confirmed their complementary activities in primary tumours and metastatic lesions. These findings might inform the development of therapies that target different branches of Wnt signalling at specific stages of metastasis.

Exosome-based bone-targeting drug delivery alleviates impaired osteoblastic bone formation and bone loss in inflammatory bowel diseases

Systematic bone loss is commonly complicated with inflammatory bowel diseases (IBDs) with unclear pathogenesis and uncertain treatment. In experimental colitis mouse models established by dextran sulfate sodium and IL-10 knockout induced with piroxicam, bone mass and quality are significantly decreased. Colitis mice demonstrate a lower bone formation rate and fewer osteoblasts in femur. Bone marrow mesenchymal stem/stromal cells (BMSCs) from colitis mice tend to differentiate into adipocytes rather than osteoblasts. Serum from patients with IBD promotes adipogenesis of human BMSCs. RNA sequencing reveals that colitis downregulates Wnt signaling in BMSCs. For treatment, exosomes with Golgi glycoprotein 1 inserted could carry Wnt agonist 1 and accumulate in bone via intravenous administration. They could alleviate bone loss, promote bone formation, and accelerate fracture healing in colitis mice. Collectively, BMSC commitment in inflammatory microenvironment contributes to lower bone quantity and quality and could be rescued by redirecting differentiation toward osteoblasts through bone-targeted drug delivery.

MLL3 loss drives metastasis by promoting a hybrid epithelial-mesenchymal transition state

Phenotypic plasticity associated with the hybrid epithelial-mesenchymal transition (EMT) is crucial to metastatic seeding and outgrowth. However, the mechanisms governing the hybrid EMT state remain poorly defined. Here we showed that deletion of the epigenetic regulator MLL3, a tumour suppressor frequently altered in human cancer, promoted the acquisition of hybrid EMT in breast cancer cells. Distinct from other EMT regulators that mediate only unidirectional changes, MLL3 loss enhanced responses to stimuli inducing EMT and mesenchymal-epithelial transition in epithelial and mesenchymal cells, respectively. Consequently, MLL3 loss greatly increased metastasis by enhancing metastatic colonization. Mechanistically, MLL3 loss led to increased IFNγ signalling, which contributed to the induction of hybrid EMT cells and enhanced metastatic capacity. Furthermore, BET inhibition effectively suppressed the growth of MLL3-mutant primary tumours and metastases. These results uncovered MLL3 mutation as a key driver of hybrid EMT and metastasis in breast cancer that could be targeted therapeutically.

Mesenchymal stem cell therapy for neurological disorders: The light or the dark side of the force?

Neurological disorders are recognized as major causes of death and disability worldwide. Because of this, they represent one of the largest public health challenges. With awareness of the massive burden associated with these disorders, came the recognition that treatment options were disproportionately scarce and, oftentimes, ineffective. To address these problems, modern research is increasingly looking into novel, more effective methods to treat neurological patients; one of which is cell-based therapies. In this review, we present a critical analysis of the features, challenges, and prospects of one of the stem cell types that can be employed to treat numerous neurological disorders-mesenchymal stem cells (MSCs). Despite the fact that several studies have already established the safety of MSC-based treatment approaches, there are still some reservations within the field regarding their immunocompatibility, heterogeneity, stemness stability, and a range of adverse effects-one of which is their tumor-promoting ability. We additionally examine MSCs' mechanisms of action with respect to in vitro and in vivo research as well as detail the findings of past and ongoing clinical trials for Parkinson's and Alzheimer's disease, ischemic stroke, glioblastoma multiforme, and multiple sclerosis. Finally, this review discusses prospects for MSC-based therapeutics in the form of biomaterials, as well as the use of electromagnetic fields to enhance MSCs' proliferation and differentiation into neuronal cells.

The prospect of tumor microenvironment-modulating therapeutical strategies

Multiple mechanisms promote tumor prosperity, which does not only depend on cell-autonomous, inherent abnormal characteristics of the malignant cells that facilitate rapid cell division and tumor expansion. The neoplastic tissue is embedded in a supportive and dynamic tumor microenvironment (TME) that nurtures and protects the malignant cells, maintaining and perpetuating malignant cell expansion. The TME consists of different elements, such as atypical vasculature, various innate and adaptive immune cells with immunosuppressive or pro-inflammatory properties, altered extracellular matrix (ECM), activated stromal cells, and a wide range of secreted/stroma-tethered bioactive molecules that contribute to malignancy, directly or indirectly. In this review, we describe the various TME components and provide examples of anti-cancer therapies and novel drugs under development that aim to target these components rather than the intrinsic processes within the malignant cells. Combinatory TME-modulating therapeutic strategies may be required to overcome the resistance to current treatment options and prevent tumor recurrence.

Kinesin family member 23, regulated by FOXM1, promotes triple negative breast cancer progression via activating Wnt/β-catenin pathway

Background

Triple negative breast cancer (TNBC) is highly malignant and has a worse prognosis, compared with other subtypes of breast cancer due to the absence of therapeutic targets. KIF23 plays a crucial role in the tumorigenesis and cancer progression. However, the role of KIF23 in development of TNBC and the underlying mechanism remain unknown. The study aimed to elucidate the biological function and regulatory mechanism of KIF23 in TNBC.

Methods

Quantitative real-time PCR and Western blot were used to determine the KIF23 expression in breast cancer tissues and cell lines. Then, functional experiments in vitro and in vivo were performed to investigate the effects of KIF23 on tumor growth and metastasis in TNBC. Chromatin immunoprecipitation assay was conducted to illustrate the potential regulatory mechanisms of KIF23 in TNBC.

Results

We found that KIF23 was significantly up-regulated and associated with poor prognosis in TNBC. KIF23 could promote TNBC proliferation, migration and invasion in vitro and in vivo. KIF23 could activate Wnt/β-catenin pathway and promote EMT progression in TNBC. In addition, FOXM1, upregulated by WDR5 via H3K4me3 modification, directly bound to the promoter of KIF23 gene to promote its transcription and accelerated TNBC progression via Wnt/β-catenin pathway. Both of small inhibitor of FOXM1 and WDR5 could inhibit TNBC progression.

Conclusions

Our findings elucidate WDR5/FOXM1/KIF23/Wnt/β-catenin axis is associated with TNBC progression and may provide a novel and promising therapeutic target for TNBC treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02373-7.

Insights into the Role of Sialylation in Cancer Metastasis, Immunity, and Therapeutic Opportunity

Sialylation is an enzymatic process that covalently attaches sialic acids to glycoproteins and glycolipids and terminates them by creating sialic acid-containing glycans (sialoglycans). Sialoglycans, usually located in the outmost layers of cells, play crucial biological roles, notably in tumor transformation, growth, metastasis, and immune evasion. Thus, a deeper comprehension of sialylation in cancer will help to facilitate the development of innovative cancer therapies. Cancer sialylation-related articles have consistently increased over the last four years. The primary subjects of these studies are sialylation, cancer, immunotherapy, and metastasis. Tumor cells activate endothelial cells and metastasize to distant organs in part by the interactions of abnormally sialylated integrins with selectins. Furthermore, cancer sialylation masks tumor antigenic epitopes and induces an immunosuppressive environment, allowing cancer cells to escape immune monitoring. Cytotoxic T lymphocytes develop different recognition epitopes for glycosylated and nonglycosylated peptides. Therefore, targeting tumor-derived sialoglycans is a promising approach to cancer treatments for limiting the dissemination of tumor cells, revealing immunogenic tumor antigens, and boosting anti-cancer immunity. Exploring the exact tumor sialoglycans may facilitate the identification of new glycan targets, paving the way for the development of customized cancer treatments.

Expression Analysis and the Roles of the Sec1 Gene in Regulating the Composition of Mouse Gut Microbiota

The Sec1 gene encodes galactose 2-L-fucosyltransferase, whereas expression during development of the Sec1 gene mouse and its effect on the composition of the gut microbiota have rarely been reported. In this study, we examined Sec1 gene expression during mouse development, constructed Sec1 knockout mice, and sequenced their gut microbial composition. It was found that Sec1 was expressed at different stages of mouse development. Sec1 knockout mice have significantly higher intraperitoneal fat accumulation and body weight than wild-type mice. Analysis of gut microbial composition in Sec1 knockout mice revealed that at the phylum level, Bacteroidetes accounted for 68.8%and 68.3% of gut microbial composition in the Sec1^-/- and Sec1^+/+ groups, respectively, and Firmicutes accounted for 27.1% and 19.7%, respectively; while Firmicutes/Bacteroidetes were significantly higher in Sec1^-/- mice than in Sec1^+/+ mice (39.4% vs. 28.8%). In verucomicrobia, it was significantly higher in Sec1^-/- mice than in Sec1^+/+ group mice. At the family level, the dominant bacteria Prevotellaceae, Akkermansiaceae, Bacteroidaceae, and Lacilltobacaceae were found to be significantly reduced in the gut of Sec1^-/- mice among Sec1^+/+ gut microbes, while Lachnospiraceae, Ruminococcaceae, Rikenellaceae, Helicobacteraceae, and Tannerellaceae were significantly increased. Indicator prediction also revealed the dominant bacteria Akkermansiaceae and Lactobacillaceae in Sec1^+/+ gut microorganisms, while the dominant bacteria Rikenellaceae, Marinifilaceae, ClostridialesvadinBB60aceae, Erysipelotrichaceae, Saccharimonadaceae, Clostridiaceae1, and Christensenellaceae in Sec1^-/- group. This study revealed that the Sec1 gene was expressed in different tissues at different time periods in mice, and Sec1 knockout mice had significant weight gain, significant abdominal fat accumulation, and significant changes in gut microbial flora abundance and metabolic function, providing a theoretical basis and data support for the study of Sec1 gene function and effects on gut microbiota-related diseases.

Aberrant Sialylation in Cancer: Therapeutic Opportunities

The surface of every eukaryotic cell is coated in a thick layer of glycans that acts as a key interface with the extracellular environment. Cancer cells have a different ‘glycan coat’ to healthy cells and aberrant glycosylation is a universal feature of cancer cells linked to all of the cancer hallmarks. This means glycans hold huge potential for the development of new diagnostic and therapeutic strategies. One key change in tumour glycosylation is increased sialylation, both on N-glycans and O-glycans, which leads to a dense forest of sialylated structures covering the cell surface. This hypersialylation has far-reaching consequences for cancer cells, and sialylated glycans are fundamental in tumour growth, metastasis, immune evasion and drug resistance. The development of strategies to inhibit aberrant sialylation in cancer represents an important opportunity to develop new therapeutics. Here, I summarise recent advances to target aberrant sialylation in cancer, including the development of sialyltransferase inhibitors and strategies to inhibit Siglecs and Selectins, and discuss opportunities for the future.

Triple-negative breast cancer metastasis involves complex epithelial-mesenchymal transition dynamics and requires vimentin

Triple-negative breast cancer (TNBC) is an aggressive subtype associated with early metastatic recurrence and worse patient outcomes. TNBC tumors express molecular markers of the epithelial-mesenchymal transition (EMT), but its requirement during spontaneous TNBC metastasis in vivo remains incompletely understood. We demonstrated that spontaneous TNBC tumors from a genetically engineered mouse model (GEMM), multiple patient-derived xenografts, and archival patient samples exhibited large populations in vivo of hybrid E/M cells that lead invasion ex vivo while expressing both epithelial and mesenchymal characteristics. The mesenchymal marker vimentin promoted invasion and repressed metastatic outgrowth. We next tested the requirement for five EMT transcription factors and observed distinct patterns of utilization during invasion and colony formation. These differences suggested a sequential activation of multiple EMT molecular programs during the metastatic cascade. Consistent with this model, our longitudinal single-cell RNA analysis detected three different EMT-related molecular patterns. We observed cancer cells progressing from epithelial to hybrid E/M and strongly mesenchymal patterns during invasion and from epithelial to a hybrid E/M pattern during colony formation. We next investigated the relative epithelial versus mesenchymal state of cancer cells in both GEMM and patient metastases. In both contexts, we observed heterogeneity between and within metastases in the same individual. We observed a complex spectrum of epithelial, hybrid E/M, and mesenchymal cell states within metastases, suggesting that there are multiple successful molecular strategies for distant organ colonization. Together, our results demonstrate an important and complex role for EMT programs during TNBC metastasis.

Targeting HECTD3-IKKα axis inhibits inflammation-related metastasis

Metastasis is the leading cause of cancer-related death. The interactions between circulating tumor cells and endothelial adhesion molecules in distant organs is a key step during extravasation in hematogenous metastasis. Surgery is a common intervention for most primary solid tumors. However, surgical trauma-related systemic inflammation facilitates distant tumor metastasis by increasing the spread and adhesion of tumor cells to vascular endothelial cells (ECs). Currently, there are no effective interventions to prevent distant metastasis. Here, we show that HECTD3 deficiency in ECs significantly reduces tumor metastasis in multiple mouse models. HECTD3 depletion downregulates expression of adhesion molecules, such as VCAM-1, ICAM-1 and E-selectin, in mouse primary ECs and HUVECs stimulated by inflammatory factors and inhibits adhesion of tumor cells to ECs both in vitro and in vivo. We demonstrate that HECTD3 promotes stabilization, nuclear localization and kinase activity of IKKα by ubiquitinating IKKα with K27- and K63-linked polyubiquitin chains at K296, increasing phosphorylation of histone H3 to promote NF-κB target gene transcription. Knockout of HECTD3 in endothelium significantly inhibits tumor cells lung colonization, while conditional knockin promotes that. IKKα kinase inhibitors prevented LPS-induced pulmonary metastasis. These findings reveal the promotional role of the HECTD3-IKKα axis in tumor hematogenous metastasis and provide a potential strategy for tumor metastasis prevention.

Review old bone, new tricks

Despite the significant progress made over the past decade with combination of molecular profiling data and the development of new clinical strategies, our understanding of metastasis remains elusive. Bone metastasis is a complex process and a major cause of mortality in breast and prostate cancer patients, for which there is no effective treatment to-date. The current review summarizes the routes taken by the metastatic cells and the interactions between them and the bone microenvironment. We emphasize the role of the specified niches and cues that promote cellular adhesion, colonization, prolonged dormancy, and reactivation. Understanding these mechanisms will provide better insights for future studies and treatment strategies for bone metastatic conditions.

Tinker, tailor, soldier, cell: the role of C-type lectins in the defense and promotion of disease

C-type lectins (CTLs) represent a large family of soluble and membrane-bound proteins which bind calcium dependently via carbohydrate recognition domains (CRDs) to glycan residues presented on the surface of a variety of pathogens. The deconvolution of a cell's glycan code by CTLs underpins several important physiological processes in mammals such as pathogen neutralization and opsonization, leukocyte trafficking, and the inflammatory response. However, as our knowledge of CTLs has developed it has become apparent that the role of this innate immune family of proteins can be double-edged, where some pathogens have developed approaches to subvert and exploit CTL interactions to promote infection and sustain the pathological state. Equally, CTL interactions with host glycoproteins can contribute to inflammatory diseases such as arthritis and cancer whereby, in certain contexts, they exacerbate inflammation and drive malignant progression. This review discusses the 'dual agent' roles of some of the major mammalian CTLs in both resolving and promoting infection, inflammation and inflammatory disease and highlights opportunities and emerging approaches for their therapeutic modulation.

Stromal Co-Cultivation for Modeling Breast Cancer Dormancy in the Bone Marrow

Cancers metastasize to the bone marrow before primary tumors can be detected. Bone marrow micrometastases are resistant to therapy, and while they are able to remain dormant for decades, they recur steadily and result in incurable metastatic disease. The bone marrow microenvironment maintains the dormancy and chemoresistance of micrometastases through interactions with multiple cell types and through structural and soluble factors. Modeling dormancy in vitro can identify the mechanisms of these interactions. Modeling also identifies mechanisms able to disrupt these interactions or define novel interactions that promote the reawakening of dormant cells. The in vitro modeling of the interactions of cancer cells with various bone marrow elements can generate hypotheses on the mechanisms that control dormancy, treatment resistance and reawakening in vivo. These hypotheses can guide in vivo murine experiments that have high probabilities of succeeding in order to verify in vitro findings while minimizing the use of animals in experiments. This review outlines the existing data on predominant stromal cell types and their use in 2D co-cultures with cancer cells.

The overall process of metastasis: From initiation to a new tumor

Metastasis-a process that involves the migration of cells from the primary site to distant organs-is the leading cause of cancer-associated death. Improved technology and in-depth research on tumors have furthered our understanding of the various mechanisms involved in tumor metastasis. Metastasis is initiated by cancer cells of a specific phenotype, which migrate with the assistance of extracellular components and metastatic traits conferred via epigenetic regulation while modifying their behavior in response to the complex and dynamic human internal environment. In this review, we have summarized the general steps involved in tumor metastasis and their characteristics, incorporating recent studies and topical issues, including epithelial-mesenchymal transition, cancer stem cells, neutrophil extracellular traps, pre-metastatic niche, extracellular vesicles, and dormancy. Several feasible treatment directions have also been summarized. In addition, the correlation between cancer metastasis and lifestyle factors, such as obesity and circadian rhythm, has been illustrated.

Tumour invasion and dissemination

Activating invasion and metastasis are one of the primary hallmarks of cancer, the latter representing the leading cause of death in cancer patients. Whilst many advances in this area have been made in recent years, the process of cancer dissemination and the underlying mechanisms governing invasion are still poorly understood. Cancer cells exhibit multiple invasion strategies, including switching between modes of invasion and plasticity in response to therapies, surgical interventions and environmental stimuli. The ability of cancer cells to switch migratory modes and their inherent plasticity highlights the critical challenge preventing the successful design of cancer and anti-metastatic therapies. This mini-review presents current knowledge on the critical models of tumour invasion and dissemination. We also discuss the current issues surrounding current treatments and arising therapeutic opportunities. We propose that the establishment of novel approaches to study the key biological mechanisms underlying the metastatic cascade is critical in finding novel targets that could ultimately lead to complete inhibition of cancer cell invasion and dissemination.

Interaction between tumor microenvironment, autophagy, and epithelial-mesenchymal transition in tumor progression

Tumor microenvironment (TME) is the ecosystem surrounding a tumor to influence tumor cells' growth, metastasis and immunological battlefield, in which the tumor systems fight against the body system. TME has been considered as the essential link between the tumorigenesis and development of neoplasm. Both nutrients intake and tumor progression to malignancy require the participation of components in TME. Epithelial-mesenchymal transition (EMT) is a key step in the metastasis of tumor cells. Cells that lost polarity and acquired migration ability are prone to metastasize. Autophagy is an important self-protective mechanism in tumor cells and a necessity for the tumor cells to respond to harmful stress. Protective autophagy benefits tumor cells while abnormal autophagy leads to cell injury or death. EMT and autophagy are directly regulated by TME. To date, there are numerous studies on TME, autophagy and EMT separately, but few on their complex interrelationships. This review aims to comprehensively analyze the existing mechanisms and convincing evidence so far to seek novel therapeutic strategies and research directions.

Cellular plasticity in bone metastasis

Metastasis is responsible for a large majority of death from malignant solid tumors. Bone is one of the most frequently affected organs in cancer metastasis, especially in breast and prostate cancer. Development of bone metastasis requires cancer cells to successfully complete a number of challenging steps, including local invasion and intravasation, survival in circulation, extravasation and initial seeding, and finally, formation of metastatic colonies after a period of dormancy or indolent growth. During this process, cancer cells often undergo a series of cellular and molecular changes to gain cellular plasticity that helps them adapt to various environments they encounter along the journey of metastasis. Understanding the mechanisms behind cellular plasticity and adaptation during the formation of bone metastasis is crucial for the development of novel therapies.