Pre-metastatic niches: organ-specific homes for metastases

Bone mineral density affects tumor growth by shaping microenvironmental heterogeneity

Breast cancer bone metastasis is a major cause of mortality in patients with advanced breast cancer. Although decreased mineral density is a known risk factor for bone metastasis, the underlying mechanisms remain poorly understood because studying the isolated effect of bone mineral density on tumor heterogeneity is challenging with conventional approaches. Moreover, mineralized biomaterials are commonly utilized for clinical bone defect repair, but how mineralized biomaterials affect the foreign body response and wound healing is unclear. Here, we investigate how bone mineral affects tumor growth and microenvironmental complexity in vivo by combining single-cell RNA-sequencing with mineral-containing or mineral-free decellularized bone matrices. We discover that the absence of bone mineral significantly influences fibroblast and immune cell heterogeneity, promoting phenotypes that increase tumor growth and alter the response to injury or disease. Importantly, we observe that the stromal response to bone mineral content depends on the murine tumor model used. While lack of bone mineral induces tumor-promoting microenvironments in both immunocompromised and immunocompetent animals, these changes are mediated by altered fibroblast phenotype in immunocompromised mice and macrophage polarization in immunocompetent mice. Collectively, our findings suggest that bone mineral density affects tumor growth by impacting microenvironmental complexity in an organism-dependent manner.

Analysing the relevance of TGF-β and its regulators in cervical cancer to identify therapeutic and diagnostic markers

The role of transforming growth factor-beta (TGF-β) is dual, such that, it inhibits tumor development in initial stage and promotes metastasis in later stage. The present study is aimed to analyse the relevance of different types of TGF-β and their receptors on the overall survival (OS) and TGF-β driven gene expression in individuals with cervical cancer (CC) using ONCODB and GEPIA databases. The in-silico gene expression analysis showed, TGF-β1 and TGFβR2 are upregulated in cells infected with human papilloma virus (HPV)16, whereas, TGF-β2, TGFβR1 and TGFβR3 expression were downregulated. In HPV 18 infected cells, TGF-β1, TGF-β2 and TGFβR1 were downregulated, meanwhile, TGF-β3, TGFβR2 and TGFβR3 were upregulated. OS analysis of CC patients with different TGF-β expression revealed that, TGF-β1, TGF-β2, TGF-β3 and TGFβR2 were associated with reduced survival rate. Further, we identified four microRNAs (miRNAs) (hsa-miR-21-5p, hsa-miR-29b-3p, hsa-miR-101-3p and hsa-miR-130a-3p) interacted favorably with TGF-β in HPV 16 and 18 positive samples using MIENTURNET. This present review further emphasizes that, targeting TGF-β could be a novel and futuristic approach for CC management and therapeutics.

Radiomics analysis of thoracic vertebral bone marrow microenvironment changes before bone metastasis of breast cancer based on chest CT

Bone metastasis from breast cancer significantly elevates patient morbidity and mortality, making early detection crucial for improving outcomes. This study utilizes radiomics to analyze changes in the thoracic vertebral bone marrow microenvironment from chest computerized tomography (CT) images prior to bone metastasis in breast cancer, and constructs a model to predict metastasis.

METHODS

This study retrospectively gathered data from breast cancer patients who were diagnosed and continuously monitored for five years from January 2013 to September 2023. Radiomic features were extracted from the bone marrow of thoracic vertebrae on non-contrast chest CT scans. Multiple machine learning algorithms were utilized to construct various radiomics models for predicting the risk of bone metastasis, and the model with optimal performance was integrated with clinical features to develop a nomogram. The effectiveness of this combined model was assessed through receiver operating characteristic (ROC) analysis as well as decision curve analysis (DCA).

RESULTS

The study included a total of 106 patients diagnosed with breast cancer, among whom 37 developed bone metastases within five years. The radiomics model's area under the curve (AUC) for the test set, calculated using logistic regression, is 0.929, demonstrating superior predictive performance compared to alternative machine learning models. Furthermore, DCA demonstrated the potential of radiomics models in clinical application, with a greater clinical benefit in predicting bone metastasis than clinical model and nomogram.

CONCLUSION

CT-based radiomics can capture subtle changes in the thoracic vertebral bone marrow before breast cancer bone metastasis, offering a predictive tool for early detection of bone metastasis in breast cancer.

Continued attention: The role of exosomal long non-coding RNAs in tumors over the past three years

This review summarizes the research on exosomal lncRNAs in tumors over the past three years. It highlights the significant roles of exosomal lncRNAs in modulating various cellular processes within the tumor microenvironment. Exosomal lncRNAs have been shown to influence the behavior of tumor cells, promoting proliferation, metastasis, epithelial-mesenchymal transition (EMT), angiogenesis, glycolysis, and contributing to tumor growth and metabolism. Moreover, exosomal lncRNAs have been found to interact with immune cells, such as modulating the functions of macrophages and influencing the overall immune response against tumors. Fibroblasts within the tumor microenvironment are also affected by exosomal lncRNAs, which can alter the extracellular matrix (ECM) and stromal composition. Notably, these exosomal lncRNAs hold promise in the diagnosis and treatment of tumors, offering potential biomarkers and therapeutic targets for improved clinical outcomes.

Distant Metastases of Breast Cancer Resemble Primary Tumors in Cancer Cell Composition but Differ in Immune Cell Phenotypes

Breast cancer is the most commonly diagnosed cancer in women, with distant metastasis being the main cause of breast cancer-related deaths. Elucidating the changes in the tumor and immune ecosystems that are associated with metastatic disease is essential to improve understanding and ultimately treatment of metastasis. Here, we developed an in-depth, spatially resolved single-cell atlas of the phenotypic diversity of tumor and immune cells in primary human breast tumors and matched distant metastases, using imaging mass cytometry to analyze a total of 75 unique antibody targets. Although the same tumor cell phenotypes were typically present in primary tumors and metastatic sites, suggesting a strong founder effect of the primary tumor, their proportions varied between matched samples. Notably, the metastatic site did not influence tumor phenotype composition, except for the brain. Metastatic sites exhibited a lower number of immune cells overall but had a higher proportion of myeloid cells as well as exhausted and cytotoxic T cells. Myeloid cells showed distinct tissue-specific compositional signatures and increased presence of potentially matrix remodeling phenotypes in metastatic sites. This analysis of tumor and immune cell phenotypic composition of metastatic breast cancer highlights the heterogeneity of the disease within patients and across distant metastatic sites, indicating myeloid cells as the predominant immune modulators that could potentially be targeted at these sites. Significance: Multiplex imaging analysis of matched primary and metastatic breast tumors provides a phenotypic and spatial map of tumor microenvironments, revealing similar compositions of cancer cells and divergent immunologic features between matched samples.

Immune Cell Profiling Reveals a Common Pattern in Premetastatic Niche Formation Across Various Cancer Types

BACKGROUND

Metastasis is the major cause of cancer-related mortality. The premetastatic niche is a promising target for its prevention. However, the generality and cellular dynamics in premetastatic niche formation have remained unclear.

AIMS

This study aimed to elucidate the generality and cellular dynamics in premetastatic niche formation.

MATERIALS AND METHODS

We performed comprehensive flow cytometric analysis of lung and peripheral immune cells at three time points (early premetastatic, late premetastatic, and micrometastatic phases) for mice with subcutaneous implants of three types of cancer cells (breast cancer, lung cancer, or melanoma cells). The immuno-cell profiles were then used to predict the metastatic phase by machine learning.

RESULTS

We found a common pattern of changes in both lung and peripheral immune cell profiles across the three cancer types, including a decrease in the proportion of eosinophils in the early premetastatic phase, an increase in that of regulatory T cells in the late premetastatic phase, and an increase in that of polymorphonuclear myeloid-derived suppressor cells and a decrease in that of B cells in the micrometastatic phase. Machine learning using immune cell profiles could predict the metastatic phase with approximately 75% accuracy.

DISCUSSION

Validation of our findings in humans will require data on the presence or absence of micrometastases in patients and the accumulation of comprehensive and temporal information on immune cells. In addition, blood proteins, extracellular vesicles, DNA, RNA, or metabolites may be useful for more accurate prediction.

CONCLUSION

The discovery of generalities in premetastatic niche formation allow prediction of metastatic phase and provide a basis for the development of methods for early detection and prevention of cancer metastasis in a cancer type-independent manner.

Aspartate signalling drives lung metastasis via alternative translation

Lung metastases occur in up to 54% of patients with metastatic tumours1,2. Contributing factors to this high frequency include the physical properties of the pulmonary system and a less oxidative environment that may favour the survival of cancer cells3. Moreover, secreted factors from primary tumours alter immune cells and the extracellular matrix of the lung, creating a permissive pre-metastatic environment primed for the arriving cancer cells4,5. Nutrients are also primed during pre-metastatic niche formation6. Yet, whether and how nutrients available in organs in which tumours metastasize confer cancer cells with aggressive traits is mostly undefined. Here we found that pulmonary aspartate triggers a cellular signalling cascade in disseminated cancer cells, resulting in a translational programme that boosts aggressiveness of lung metastases. Specifically, we observe that patients and mice with breast cancer have high concentrations of aspartate in their lung interstitial fluid. This extracellular aspartate activates the ionotropic N-methyl-D-aspartate receptor in cancer cells, which promotes CREB-dependent expression of deoxyhypusine hydroxylase (DOHH). DOHH is essential for hypusination, a post-translational modification that is required for the activity of the non-classical translation initiation factor eIF5A. In turn, a translational programme with TGFβ signalling as a central hub promotes collagen synthesis in lung-disseminated breast cancer cells. We detected key proteins of this mechanism in lung metastases from patients with breast cancer. In summary, we found that aspartate, a classical biosynthesis metabolite, functions in the lung environment as an extracellular signalling molecule to promote aggressiveness of metastases.

Regulation of metastatic organotropism

Metastasis is responsible for most cancer-related deaths. Different cancers have their own preferential sites of metastases, a phenomenon termed metastatic organotropism. The mechanisms underlying organotropism are multifactorial and include the generation of a pre-metastatic niche (PMN), metastatic homing, colonization, dormancy, and metastatic outgrowth. Historically, studies of metastatic organotropism have been limited by a lack of models allowing direct comparison of cells exhibiting different patterns of tropism. However, new innovative models and large-scale sequencing efforts have propelled organotropism research. Herein, we summarize the recent discoveries in metastatic organotropism regulation, focusing on lung, liver, brain, and bone tropism. We discuss how emerging technologies are continuing to improve our ability to model and, hopefully, predict and treat organotropism.

[Myeloid-derived suppressor cells as important factors and potential targets for breast cancer progression]

Recurrence and metastasis remain the leading cause of death in breast cancer patients due to the lack of effective treatment. A microenvironment suitable for cancer cell growth, referred to as pre-metastatic niche (PMN), is formed in distant organs before metastasis occurs. Myeloid-derived suppressor cells (MDSCs) are a heterogenous population of immature myeloid cells with immunosuppressive effects. They can expand in large numbers in breast cancer patients and participate in the formation of PMN. MDSCs can remodel the extracellular matrix of pulmonary vascular endothelial cells and recruit cancer stem cells to promote the lung metastasis of breast cancer. Furthermore, MDSCs facilitate immune evasion of breast cancer cells to impact the efficacy of immunotherapy. It is proposed that MDSCs represent a potential therapeutic target for the inhibition of recurrence and metastasis in breast cancer. Therapeutic strategies targeting MDSCs have shown promising efficacy in preclinical studies and clinical trials. This review presents a summary of the principal factors involved in the recruitment and activation of MDSCs during the formation of PMN, and outlines MDSCs functions such as immunosuppression and the current targeted therapies against MDSCs, aiming to provide new ideas for the treatment of distant metastases in breast cancer.

Reprogramming tumor-associated macrophages with lipid nanosystems reduces PDAC tumor burden and liver metastasis

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) requires innovative therapeutic strategies to counteract its progression and metastatic potential. Since the majority of patients are diagnosed with advanced metastatic disease, treatment strategies targeting not only the primary tumor but also metastatic lesions are needed. Tumor-Associated Macrophages (TAMs) have emerged as central players, significantly influencing PDAC progression and metastasis. Our objective was to validate an innovative therapeutic strategy involving the reprogramming of TAMs using lipid nanosystems to prevent the formation of a pro-metastatic microenvironment in the liver.

RESULTS

In vitro results demonstrate that M2-polarized macrophages lose their M2-phenotype following treatment with lipid nanoemulsions composed of vitamin E and sphingomyelin (VitE:SM), transitioning to an M0/M1 state. Specifically, VitE:SM nanoemulsion treatment decreased the expression of macrophage M2 markers such as Arg1 and Egr2, while M1 markers such as Cd86, Il-1b and Il-12b increased. Additionally, the TGF-βR1 inhibitor Galunisertib (LY2157299) was loaded into VitE:SM nanoemulsions and delivered to C57BL/6 mice orthotopically injected with KPC PDAC tumor cells. Treated mice showed diminished primary tumor growth and reduced TAM infiltration in the liver. Moreover, we observed a decrease in liver metastasis with the nanoemulsion treatment in an intrasplenic model of PDAC liver metastasis. Finally, we validated the translatability of our VitE:SM nanosystem therapy in a human cell-based 3D co-culture model in vivo, underscoring the pivotal role of macrophages in the nanosystem's therapeutic effect in the context of human PDAC metastasis.

CONCLUSIONS

The demonstrated effectiveness and safety of our nanosystem therapy highlights a promising therapeutic approach for PDAC, showcasing its potential in reprogramming TAMs and mitigating the occurrence of liver metastasis.

Ovarian cancer-derived TGF-β1 induces cancer-associated adipocytes formation by activating SMAD3/TRIB3 pathway to establish pre-metastatic niche

Ovarian cancer (OC) is prone to adipose tissue metastasis. However, the underlying molecular mechanisms remain elusive. Here, we observed that omental adipocytes were induced into cancer-associated adipocytes (CAAs) by OC-derived TGF-β1 to establish a pre-metastatic niche (PMN) through collagen and fibronectin secretion. Mechanistically, OC-derived TGF-β1 binds to adipocyte membrane receptors and thus activates intracellular signaling by SMAD3 phosphorylation. The activation of TGF-β1/SMAD3 signaling pathway dedifferentiates adipocytes into CAAs by upregulating Tribbles homolog 3 (TRIB3), which suppresses the phosphorylation of CEBPβ. Additionally, CAAs secrete collagen I, collagen VI, and fibronectin to remodel the extracellular matrix and promote the adhesion of OC cells. Pharmacological inhibition of the TGF-β1/SMAD3 pathway significantly inhibits CAAs and PMN formation, thereby reducing the OC metastatic burden. Our findings indicate that the formation of CAAs and PMN in adipose tissues facilitates OC cell implantation and blocking the TGF-β1/SMAD3 signaling pathway could prevent OC omental metastasis.

Basement membranes in lung metastasis growth and progression

The lung is a highly vascularized tissue that often harbors metastases from various extrathoracic malignancies. Lung parenchyma consists of a complex network of alveolar epithelial cells and microvessels, structured within an architecture defined by basement membranes. Consequently, understanding the role of the extracellular matrix (ECM) in the growth of lung metastases is essential to uncover the biology of this pathology and developing targeted therapies. These basement membranes play a critical role in the progression of lung metastases, influencing multiple stages of the metastatic cascade, from the acquisition of an aggressive phenotype to intravasation, extravasation and colonization of secondary sites. This review examines the biological composition of basement membranes, focusing on their core components-collagens, fibronectin, and laminin-and their specific roles in cancer progression. Additionally, we discuss the function of integrins as primary mediators of cell adhesion and signaling between tumor cells, basement membranes and the extracellular matrix, as well as their implications for metastatic growth in the lung. We also explore vascular co-option (VCO) as a form of tumor growth resistance linked to basement membranes and tumor vasculature. Finally, the review covers current clinical therapies targeting tumor adhesion, extracellular matrix remodeling, and vascular development, aiming to improve the precision and effectiveness of treatments against lung metastases.

Recent Advances in Microfluidics for Nucleic Acid Analysis of Small Extracellular Vesicles in Cancer

Small extracellular vesicles (sEVs) are membranous vesicles released from cellular structures through plasma membrane budding. These vesicles contain cellular components such as proteins, lipids, mRNAs, microRNAs, long-noncoding RNA, circular RNA, and double-stranded DNA, originating from the cells they are shed from. Ranging in size from ≈25 to 300 nm and play critical roles in facilitating cell-to-cell communication by transporting signaling molecules. The discovery of sEVs in bodily fluids and their involvement in intercellular communication has revolutionized the fields of diagnosis, prognosis, and treatment, particularly in diseases like cancer. Conventional methods for isolating and analyzing sEVs, particularly their nucleic acid content face challenges including high costs, low purity, time-consuming processes, limited standardization, and inconsistent yield. The development of microfluidic devices, enables improved precision in sorting, isolating, and molecular-level separation using small sample volumes, and offers significant potential for the enhanced detection and monitoring of sEVs associated with cancer. These advanced techniques hold great promise for creating next-generation diagnostic and prognostic tools given their possibility of being cost-effective, simple to operate, etc. This comprehensive review explores the current state of research on microfluidic devices for the detection of sEV-derived nucleic acids as biomarkers and their translation into practical point-of-care and clinical applications.

Metabolic insights into tumor lymph node metastasis in melanoma

Although accounting for only a small amount of skin cancers, melanoma contributes prominently to skin cancer-related deaths, which are mostly caused by metastatic diseases, and lymphatic metastasis constitutes the main route. In this review, we concentrate on the metabolic mechanisms of tumor lymph node (LN) metastasis in melanoma. Two hypotheses of melanoma LN metastasis are introduced, which are the premetastatic niche (PMN) and parallel progression model. Dysregulation of oxidative stress, lactic acid concentration, fatty acid synthesis, amino acid metabolism, autophagy, and ferroptosis construct the metabolic mechanisms in LN metastasis of melanoma. Moreover, melanoma cells also promote LN metastasis by interacting with non-tumor cells through metabolic reprogramming in TIME. This review will deepen our understanding of the mechanism of lymph node metastasis in melanoma.

Salivary adenoid cystic carcinoma-derived α2,6-sialylated extracellular vesicles increase vascular permeability by triggering ER-stress in endothelial cells and promote lung metastasis

Salivary adenoid cystic carcinoma (SACC) tends to metastasize to the lungs in the early stages of the disease. Factors secreted by the primary tumor can induce the formation of a supportive microenvironment in distant organs prior to metastasis, a process known as pre-metastatic niche (PMN) formation. Extracellular vesicles (EVs) participate in PMN formation. In this study, α2,6-sialylation of EVs derived from SACC cells with high metastatic potential increased vascular permeability, thereby facilitating tumor metastasis to the lungs. Mechanistic studies indicated that EV α2,6-sialylation triggers protein kinase R-like endoplasmic reticulum kinase (PERK)-eukaryotic initiation factor 2α (eIF2α)-dependent activation of endoplasmic reticulum (ER) stress in the endothelium, leading to the disruption of vascular endothelial cadherin membrane expression. Sialidase or an ER stress inhibitor rescued vascular permeability induced by SACC EVs, which decreased the number of SACC cells extravasating into the lungs both in vitro and in vivo. This study identified a critical role of α2,6-sialylation of SACC EVs in lung metastasis. The findings indicate that EV α2,6-sialylation-induced ER stress in endothelial cells might be a therapeutic target for preventing SACC lung metastasis.

Tumor-derived exosomes: Unravelling the pathogenesis of pancreatic cancer with liver metastases and exploring the potential for clinical translation

Pancreatic cancer (PC) is one of the most malignant solid cancers, and PC metastasis, particularly liver metastasis, is a major cause of cancer mortality. A key event in tumor metastasis is the formation of pre-metastatic niche (PMN), which provides a microenvironment conducive to tumor cells colonization and progression. Various molecules loaded in tumor-derived exosomes (TDEs) contribute to PMN formation and distant tumor metastasis, by regulating immune and stromal cell function, inducing angiogenesis, and promoting metabolic reprogramming. Therefore, therapies targeting PMN may offer novel advantages to prevent tumor metastasis at an earlier stage. In this review, we summarize multifaceted mechanisms underlying hepatic PMN formation, with a focus on how PC TDEs participate in angiogenesis and vascular permeability, create immune suppressive microenvironment, remodel the extracellular matrix, and regulate metabolic reprogramming. In addition, we highlight the promise of TDEs for early diagnosis and effective therapy of PC liver metastases.

Exosomal signaling in cancer metastasis: Molecular insights and therapeutic opportunities

Exosomes are membrane-bound extracellular vesicles that play a role in exchanging biological products across membranes and serve as intermediaries in intercellular communication to maintain normal homeostasis. Numerous molecules, including lipids, proteins, and nucleic acids are enclosed in exosomes. Exosomes are constantly released into the extracellular environment and exhibit distinct characteristics based on the secreted cells that produce them. Exosome-mediated cell-to-cell communication has reportedly been shown to affect multiple cancer hallmarks, such as immune response modulation, pre-metastatic niche formation, angiogenesis, stromal cell reprogramming, extracellular matrix architecture remodeling, or even drug resistance, and eventually the development and metastasis of cancer cells. Exosomes can be used as therapeutic targets and possible diagnostic biomarkers by selectively loading oncogenic molecules into them. We highlight the important roles that exosomes play in cancer development in this review, which may lead to the development of fresh approaches for future clinical uses.

Circulating tumor cells shed large extracellular vesicles in capillary bifurcations that activate endothelial and immune cells

Circulating tumor cells (CTCs) and their clusters are the drivers of metastasis, but we have an incomplete understanding of how they interact with capillary beds. Using microfluidic models mimicking human capillary bifurcations, we observed cell size- and bifurcation-dependent shedding of nuclei-free fragments by patient CTCs, CTC-derived explant cells and numerous cancer cell lines. Shedding reduced cell sizes up to 61%, facilitating their transit through bifurcations. We demonstrated that shed fragments were a novel subclass of large extracellular vesicles (LEVs), "shearosomes", that require shear stress for their biogenesis and whose proteome was associated with immune-related pathways. Shearosomes exhibited functions characteristic of previously identified EVs including cell-directed internalization by endothelial and immune cells, and intercellular communication abilities such as disruption of endothelial barrier integrity, polarization of monocytes into M2 tumor-promoting macrophages and interactions between endothelial and immune cells. Cumulatively, these findings suggest that CTCs shed shearosomes in capillary beds that drive key processes involved in the formation of pre-metastatic niches.

Macrophages promote pre-metastatic niche formation of breast cancer through aryl hydrocarbon receptor activity

Macrophages that acquire an immunosuppressive phenotype play a crucial role in establishing the pre-metastatic niche (PMN), which is essential for facilitating breast cancer metastasis to distant organs. Our study showed that increased activity of the aryl hydrocarbon receptor (AHR) in lung macrophages plays a crucial role in establishing the immunosuppressive PMN in breast cancer. Specifically, AHR activation led to high expression of PD-L1 on macrophages by directly binding to the promoter of Pdl1. This upregulation of PD-L1 promoted the differentiation of regulatory T cells (Tregs) within the PMN, further enhancing immunosuppressive conditions. Mice with Ahr conditional deletion in macrophages had reduced lung metastasis of breast cancer. The elevated AHR levels in PMN macrophages were induced by GM-CSF, which was secreted by breast cancer cells. Mechanistically, the activated STAT5 signaling pathway induced by GM-CSF prevented AHR from being ubiquitinated, thereby sustaining its activity in macrophages. In breast cancer patients, the expression of AHR and PD-L1 was correlated with increased Treg cell infiltration, and higher levels of AHR were associated with a poor prognosis. These findings reveal that the crosstalk of breast cancer cells, lung macrophages, and Treg cells via the GM-CSF-STAT5-AHR-PD-L1 cascade modulates the lung pre-metastatic niche during breast cancer progression.

Leptomeningeal metastatic disease: new frontiers and future directions

Leptomeningeal metastatic disease (LMD), encompassing entities of 'meningeal carcinomatosis', neoplastic meningitis' and 'leukaemic/lymphomatous meningitis', arises secondary to the metastatic dissemination of cancer cells from extracranial and certain intracranial malignancies into the leptomeninges and cerebrospinal fluid. The clinical burden of LMD has been increasing secondary to more sensitive diagnostics, aggressive local therapies for discrete brain metastases, and improved management of extracranial disease with targeted and immunotherapeutic agents, resulting in improved survival. However, owing to drug delivery challenges and the unique microenvironment of LMD, novel therapies against systemic disease have not yet translated into improved outcomes for these patients. Underdiagnosis and misdiagnosis are common, response assessment remains challenging, and the prognosis associated with this disease of whole neuroaxis remains extremely poor. The dearth of effective therapies is further challenged by the difficulties in studying this dynamic disease state. In this Review, a multidisciplinary group of experts describe the emerging evidence and areas of active investigation in LMD and provide directed recommendations for future research. Drawing upon paradigm-changing advances in mechanistic science, computational approaches, and trial design, the authors discuss domain-specific and cross-disciplinary strategies for optimizing the clinical and translational research landscape for LMD. Advances in diagnostics, multi-agent intrathecal therapies, cell-based therapies, immunotherapies, proton craniospinal irradiation and ongoing clinical trials offer hope for improving outcomes for patients with LMD.

Implication of the Extracellular Matrix in Metastatic Tumor Cell Dormancy

Metastasis is the main cause of cancer-related deaths. The formation and growth of metastasis is a multistep process. Tumor cells extravasating in the secondary organ are in contact with a new microenvironment and a new extracellular matrix (ECM), called the metastatic niche. Some components of the ECM, such as periostin, can induce tumor cell growth in macrometastasis. In contrast, other components, such as Thrombospondin 1 (TSP-1), can maintain isolated cells in a dormant state. During dormancy, intracellular signaling activation, such as p38, maintains tumor cells arrested in the cell-cycle G0 phase for years. At any moment, stress can induce ECM modifications and binding to their specific receptors (mainly integrins) and reactivate dormant tumor cell growth in macrometastasis. In this review, we describe the tumor microenvironment of the different niches implicated in tumor cell dormancy. The role of ECM components and their associated receptors and intracellular signaling in the reactivation of dormant tumor cells in macrometastasis will be emphasized. We also present the different methodologies and experimental approaches used to study tumor cell dormancy. Finally, we discuss the current and future treatment strategies to avoid late metastasis relapse in patients.

Breast cancer stem cell-derived exosomal lnc-PDGFD induces fibroblast-niche formation and promotes lung metastasis

Triple-negative breast cancer (TNBC) is the most aggressive subtype with high metastatic potential and lack of therapeutic targets. Breast cancer stem cells (BCSCs) are enriched in TNBC and contribute to its metastatic propensity. Accumulating evidence suggests that cancer-derived exosomes are key drivers of premetastatic niche formation in distal organs. However, the function and underlying mechanism of BCSC-derived exosomes in TNBC metastasis remain elusive. Here, we demonstrated that BCSC-derived exosomes exhibit a greater capacity to activate fibroblasts and promote TNBC cell metastasis to the lung than non-BCSC-derived exosomes. Additionally, we found that upregulation of exosomal long non-coding RNA platelet derived growth factor D (lnc-PDGFD) expression in BCSCs is responsible for fibroblast activation through YBX1/NF-kB signaling in the lung. Activated fibroblasts further promote tumor progression by secreting IL-11. Taken together, BCSC-derived exosomes enriched with lnc-PDGFD could activate fibroblasts, thereby facilitating lung metastasis in TNBC patients. These results provide new insights into the mechanism of TNBC metastasis to the lung.

Endothelial Pim3 kinase protects the vascular barrier during lung metastasis

Endothelial cells (ECs) form a tissue-specific barrier for disseminating cancer cells in distant organs. However, the molecular regulation of the ECs in the metastatic niche remains unclear. Here, we analyze using scRNA-Seq, the transcriptional reprogramming of lung ECs six hours after the arrival of melanoma cells in mouse lungs. We discover a reactive capillary EC cluster (rCap) that increases from general capillary ECs in response to infiltrating cancer cells. rCap is enriched for angiogenic and inflammatory pathways and is also found in human lung datasets. The JAK-STAT activated oncogenic Pim3 kinase is a marker of rCap, being upregulated in spontaneous metastasis models. Notably, PIM inhibition increases vascular leakage and metastatic colonization and impairs the EC barrier by decreasing the junctional cadherin-5 and catenins α, β and δ. These results highlight the pulmonary endothelium's plasticity and its protection by PIM3, which may impair the efficacy of PIM inhibitors in cancer therapies.

The Lymphatic Vascular System in Extracellular Vesicle-Mediated Tumor Progression

Tumor growth and progression require molecular interactions between malignant and host cells. In recent years, extracellular vesicles (EVs) emerged as an important pillar of such interactions, carrying molecular information from their donor cells to distant recipient cells. Thereby, the phenotype and function of the recipient cells are altered, which may facilitate tumor immune escape and tumor metastasis to other organs through the formation of pre-metastatic niches. A prerequisite for these effects of tumor cell-derived EVs is an efficient transport system from the site of origin to the body periphery. Here, we highlight the role of the lymphatic vascular system in the distribution and progression-promoting functions of tumor cell-derived EVs. Importantly, the lymphatic vascular system is the primary drainage system for interstitial fluid and its soluble, particulate, and cellular contents, and therefore represents the principal route for regional (i.e., to tumor-draining lymph nodes) and systemic distribution of EVs derived from solid tumors. Furthermore, recent studies highlighted the tumor-draining lymph node as a crucial site where tumor-derived EVs exert their effects. A deeper mechanistic understanding of how EVs gain access to the lymphatic vasculature, how they interact with their recipient cells in tumor-draining lymph nodes and beyond, and how they induce phenotypic and functional maladaptation will be instrumental to identify new molecular targets and conceive innovative approaches for cancer therapy.

How the bone microenvironment shapes the pre-metastatic niche and metastasis

The bone is a frequent metastatic site, with changes in the mineralized bone and the bone marrow milieu that can also prime other sites for metastasis by educating progenitor cells to support metastatic spread. Stromal and immune populations cooperatively maintain the organizationally complex bone niches and are dysregulated in the presence of a distant primary tumor and metastatic disease. Interrogating the bone niches that facilitate metastatic spread using innovative technologies holds the potential to aid in preventing metastasis in and mediated by the bone. Here, we review recent advances in bone niche biology and its adaptations in the context of cancer.

Liquid biopsy in lung cancer: The role of circulating tumor cells in diagnosis, treatment, and prognosis

Despite numerous therapeutic advancements, such as immune checkpoint inhibitors, lung cancer continues to be the leading cause of cancer-related mortality. Therefore, the identification of cancer at an early stage is becoming a significant subject in contemporary oncology. Despite significant advancements in early detection tactics in recent decades, they continue to provide challenges because of the inconspicuous symptoms observed during the early stages of the primary tumor. Presently, tumor biomarkers and imaging techniques are extensively employed across different forms of cancer. Nevertheless, every approach has its own set of constraints. In certain instances, the detriments outweigh the advantages. Hence, there is an urgent need to enhance early detection methods. Currently, liquid biopsy is considered more flexible and not intrusive method in comparison to conventional test for early detection. Circulating tumor cells (CTCs) are crucial components of liquid biopsy and have a pivotal function in the spread and formation of secondary tumors. These indicators show great promise in the early identification of cancer. This study presents a comprehensive examination of the methodologies employed for the isolation and enrichment of circulating tumor cells (CTCs) in lung cancer. Additionally, it explores the formation of clusters of CTCs, which have a pivotal function in facilitating the effective dissemination of cancer to distant organs. In addition, we discuss the importance of CTCs in the detection, treatment, and prognosis of lung cancer.

Cancer-induced systemic pre-conditioning of distant organs: building a niche for metastatic cells

From their early genesis, tumour cells integrate with the surrounding normal cells to form an abnormal structure that is tightly integrated with the host organism via blood and lymphatic vessels and even neural associations. Using these connections, emerging cancers send a plethora of mediators that efficiently perturb the entire organism and induce changes in distant tissues. These perturbations serendipitously favour early metastatic establishment by promoting a more favourable tissue environment (niche) that supports the persistence of disseminated tumour cells within a foreign tissue. Because the establishment of early metastatic niches represents a key limiting step for metastasis, the creation of a more suitable pre-conditioned tissue strongly enhances metastatic success. In this Review, we provide an updated view of the mechanisms and mediators of primary tumours described so far that induce a pro-metastatic conditioning of distant organs, which favours early metastatic niche formation. We reflect on the nature of cancer-induced systemic conditioning, considering that non-cancer-dependent perturbations of tissue homeostasis are also able to trigger pro-metastatic conditioning. We argue that a more holistic view of the processes catalysing metastatic progression is needed to identify preventive or therapeutic opportunities.

Delineating the nexus between gut-intratumoral microbiome and osteo-immune system in bone metastases

Emerging insights in osteoimmunology have enabled researchers to explore in depth the role of immune modulation in regulating bone health. Bone is one of the common sites of metastasis notably in case of breast cancer, prostate cancer and several other cancer types. High calcium ion concentration and presence of several factors within the mineralized bone matrix including TGF-β, BMP etc., aid in tumor growth and proliferation. Accumulating evidence has substantiated the role of the gut-microbiota (GM) in tumorigenesis, further providing a strong impetus for the growing "immune-cancer-gut microbiota" relationship. Recent advancements in research further highlight the importance of the intra-tumor microbiota in conjunction with GM in cancer metastasis. Intratumoral microbiota owing to their ability to cause genetic instability, mutations, and epigenetic modifications within the tumor microenvironment, has been recognized to affect cancer cell physiology. The host microbiota and immune system crosstalk shapes the innate and adaptive arms of the immune system, which is the key player in cancer progression. In this review, we aim to decipher the role of microorganisms mediating bone metastasis by shedding light on the immuno-onco-microbiome (IOM) axis. We discussed the feasible cancer therapeutic interventions based on the modulation of the microbiome-immune cell axis which includes prebiotics, probiotics, and postbiotics. Here, we leverage the conceptual framework based on the published articles on microbiota-based therapies to target bone metastases. Understanding this complicated nexus will provide insights into fundamental factors governing bone metastases which will subsequently help in managing this malignancy with better efficacy.

A review on dendrimer-based nanoconjugates and their intracellular trafficking in cancer photodynamic therapy

Nanotechnology-based cancer treatment has received considerable attention, and these treatments generally use drug-loaded nanoparticles (NPs) to target and destroy cancer cells. Nanotechnology combined with photodynamic therapy (PDT) has demonstrated positive outcomes in cancer therapy. Combining nanotechnology and PDT is effective in targeting metastatic cancer cells. Nanotechnology can also increase the effectiveness of PDT by targeting cells at a molecular level. Dendrimer-based nanoconjugates (DBNs) are highly stable and biocompatible, making them suitable for drug delivery applications. Moreover, the hyperbranched structures in DBNs have the capacity to load hydrophobic compounds, such as photosensitizers (PSs) and chemotherapy drugs, and deliver them efficiently to tumour cells. This review primarily focuses on DBNs and their potential applications in cancer treatment. We discuss the chemical design, mechanism of action, and targeting efficiency of DBNs in tumour metastasis, intracellular trafficking in cancer treatment, and DBNs' biocompatibility, biodegradability and clearance properties. Overall, this study will provide the most recent insights into the application of DBNs and PDT in cancer therapy.

Exosomal integrins in tumor progression, treatment and clinical prediction (Review)

Integrins are a large family of cell adhesion molecules involved in tumor cell differentiation, migration, proliferation and neovascularization. Tumor cell‑derived exosomes carry a large number of integrins, which are closely associated with tumor progression. As crucial mediators of intercellular communication, exosomal integrins have gained attention in the field of cancer biology. The present review examined the regulatory mechanisms of exosomal integrins in tumor cell proliferation, migration and invasion, and emphasized their notable roles in tumor initiation and progression. The potential of exosomal integrins as drug delivery systems in cancer treatment was explored. Additionally, the potential of exosomal integrins in clinical tumor prediction was considered, while summarizing their applications in diagnosis, prognosis assessment and treatment response prediction. Thus, the present review aimed to provide guidance and insights for future basic research and the clinical translation of exosomal integrins. The study of exosomal integrins is poised to offer new perspectives and methods for precise cancer treatment and clinical prediction.

Cancer treatments as paradoxical catalysts of tumor awakening in the lung

Much of the fatality of tumors is linked to the growth of metastases, which can emerge months to years after apparently successful treatment of primary tumors. Metastases arise from disseminated tumor cells (DTCs), which disperse through the body in a dormant state to seed distant sites. While some DTCs lodge in pre-metastatic niches (PMNs) and rapidly develop into metastases, other DTCs settle in distinct microenvironments that maintain them in a dormant state. Subsequent awakening, induced by changes in the microenvironment of the DTC, causes outgrowth of metastases. Hence, there has been extensive investigation of the factors causing survival and subsequent awakening of DTCs, with the goal of disrupting these processes to decrease cancer lethality. We here provide a detailed overview of recent developments in understanding of the factors controlling dormancy and awakening in the lung, a common site of metastasis for many solid tumors. These factors include dynamic interactions between DTCs and diverse epithelial, mesenchymal, and immune cell populations resident in the lung. Paradoxically, among key triggers for metastatic outgrowth, lung tissue remodeling arising from damage induced by the treatment of primary tumors play a significant role. In addition, growing evidence emphasizes roles for inflammation and aging in opposing the factors that maintain dormancy. Finally, we discuss strategies being developed or employed to reduce the risk of metastatic recurrence.

Remodeling of the extracellular matrix by serine proteases as a prerequisite for cancer initiation and progression

The extracellular matrix (ECM) serves as a physical scaffold for tissues that is composed of structural proteins such as laminins, collagens, proteoglycans and fibronectin, forming a three dimensional network, and a wide variety of other matrix proteins with ECM-remodeling and signaling functions. The activity of ECM-associated signaling proteins is tightly regulated. Thus, the ECM serves as a reservoir for water and growth regulatory signals. The ECM architecture is dynamically modulated by multiple serine proteases that process both structural and signaling proteins to regulate physiological processes such as organogenesis and tissue homeostasis but they also contribute to pathological events, especially cancer progression. Here, we review the current literature regarding the role of ECM remodeling by serine proteases (KLKs, uPA, furin, HtrAs, granzymes, matriptase, hepsin) in tumorigenesis.

Osteoimmunology in bone malignancies: a symphony with evil

Bone marrow is pivotal for normal hematopoiesis and immune responses, yet it is often compromised by malignancies. The bone microenvironment (BME), composed of bone and immune cells, maintains skeletal integrity and blood production. The emergence of primary or metastatic tumors in the skeletal system results in severe complications and contributes significantly to cancer-related mortality. These tumors set off a series of interactions among cancer, bone, and immune cells, and disrupt the BME locally or distantly. However, the drivers, participants, and underlying molecules of these interactions are not fully understood. This review explores the crosstalk between bone metabolism and immune responses, synthesizing current knowledge on the intersection of cancer and osteoimmune biology. It outlines how bone marrow immune cells can either facilitate or hinder tumor progression by interacting with bone cells and pinpoints the molecules responsible for immunosuppression within bone tumors. Moreover, it discusses how primary tumors remotely alter the BME, leading to systemic immune suppression in cancer patients. This knowledge provides critical rationales for emerging immunotherapies in the treatment of bone-related tumors. Taken together, by summarizing the intricate relationship between tumor cells and the BME, this review aims to deepen the understanding of the diversity, complexity, and dynamics at play during bone tumor progression. Ultimately, it highlights the potential of targeting bone-tumor interactions to correct aberrant immune functions, thereby inhibiting tumor growth and metastasis.

Single cell landscape of potential mechanisms in primary and metastatic hepatocellular carcinoma

Hepatocellular carcinoma metastasis occurs mainly in the portal vein and lymph node metastasis, and is the main cause of patient death. However, the cellular origins and driving mechanisms of hepatocellular carcinoma metastasis have not been elucidated. In this study, we found that different tumor metastasis samples originated from different branches of the primary tumor subclone. A large number of sequence data confirmed the correlation between tumor metastasis index and metastasis and prognosis. Patients with a high index generally had a poor prognosis and abnormal metabolic function. Finally, we recommended a candidate therapy for each metastatic direction. This study explains the cellular origin and underlying mechanisms of hepatocellular carcinoma metastasis at the single-cell level and identifies drugs for its targeted therapy. It also provides a new research idea for the study of hepatocellular carcinoma metastasis and early identification of cancer metastasis from cellular resolution.

S100A8 as a potential therapeutic target for cancer metastasis

Metastasis is a major cause of cancer-related deaths. Similar to the tumor microenvironment formation, the premetastatic niche develops in distant organs before the arrival of tumor cells. Elucidating the mechanism(s) underlying premetastatic niche formation could contribute to the establishment of effective therapeutic targets for metastasis. Our research indicates that primary tumors hijack Toll-like receptor 4 (TLR4) signaling to establish a premetastatic niche in the lungs by utilizing an endogenous ligand S100A8. S100A8 is expressed not only in immune cells but also in various types of tumor cells. By focusing on S100A8 as a therapeutic target, we identified at least three multivalent S100A8 inhibitory peptides. Here, we review the tumor-promoting role of S100A8-mediated TLR4 signaling and propose S100A8 as a potential therapeutic target for aggressive cancer.

Single-cell sequencing reveals PTX3 involvement in ovarian cancer metastasis

BACKGROUND

Pentraxin 3 (PTX3) has been associated with the development and progression of various malignant tumors. However, its roles and the mechanisms underlying its involvement in ovarian cancer (OC) peritoneal metastasis remain unclear.

METHODS

Single-cell RNA sequencing (scRNA-seq) and immunohistochemistry (IHC) were conducted to determine the expression profiles, potential functionalities, and underlying mechanisms of PTX3 within the context of OC. To assess the proliferative response of OC cells, we utilized both EdU (5-ethynyl-2' -deoxyuridine) and CCK8 assays. The role of PTX3 in facilitating cell migration and invasion was quantified through the use of Transwell assays. The protein expression levels were meticulously analyzed via Western blotting. Furthermore, to explore the interactions between proteins, we conducted immunofluorescence (IF) staining and co-immunoprecipitation (Co-IP) experiments. To determine the factors responsible for the upregulation of PTX3, we performed both coculture and suspension assays, providing a comprehensive approach to understanding the regulatory mechanisms involved.

RESULTS

This study confirmed, for the first time, that the expression of PTX3 in OC metastatic lesions is greater than that in primary lesions and that tumor cells with high PTX3 expression have greater metastatic ability. PTX3 can activate the EMT and NF-κB signaling pathways in OC cells and can interact with the TLR4 and CD44 receptors in OC cells. Additionally, PTX3's modulation of the EMT and NF-κB pathways is partially dependent on its interaction with TLR4. Furthermore, this study revealed the intercellular regulatory network related to PTX3 in OC cells via bioinformatic analysis. High levels of PTX3 in OC cells potentially enhance the attraction of dendritic cells (DCs) and CD4 + T cells while diminishing the recruitment of B cells and CD8 + T cells. Finally, this study indicated that PTX3 upregulation was driven by multiple factors, including specific transcription factors (TFs) and modifications within the tumor microenvironment (TME).

CONCLUSIONS

Our research revealed the contribution of PTX3 to the peritoneal dissemination process in OC patients, identifying a novel potential biomarker and therapeutic target for this disease.

Doxorubicin- and Selenium-Incorporated Mesoporous Silica Nanoparticles as a Combination Therapy for Osteosarcoma

Doxorubicin (Dox) is a promising anticancer chemotherapeutic, which has been widely investigated in osteosarcoma (OS) treatment. However, there are several disadvantages regarding its clinical use. Specifically, Dox has low specificity toward cancer cells, which can lead to serious side effects. In addition, cancer cells can develop resistance toward Dox, reducing its therapeutic efficiency. Combination therapy (CT) facilitated by nanoparticle delivery systems is a promising strategy to overcome these drawbacks. In this study, we investigated the effectiveness of Dox and selenium (Se) CT using mesoporous silica nanoparticles (MSN) coated with hyaluronic acid (HA) as drug carriers. We hypothesized that combining Se as a second agent can increase Dox anti-OS effectiveness and that MSN can be used to facilitate dual drug delivery. In our system, HA was used as a gatekeeper to control the intracellular release of Se/Dox by means of its pH-responsive degradation. CT therapy using MSNs coated with HA led to a higher OS inhibitory efficiency in vitro compared to MSNs carrying either Se or Dox alone. This study demonstrates that using MSNs for the dual delivery of Se and Dox is a promising method for OS therapy.

LSD1 deficiency in breast cancer cells promotes the formation of pre-metastatic niches

Lysine-specific demethylase 1 (LSD1), a histone demethylating enzyme, plays a crucial role in cancer metastasis. Studies show LSD1 knockout promotes breast cancer lung metastasis, but it's unknown if it alters the lung microenvironment for metastasis. In this study, we investigated the effects of exosomes from LSD1-knockdown (LSD1 KD) breast cancer cells on pre-metastatic niche formation. Injecting exosomes from LSD1 KD cells in mice resulted in a substantial increase in lung colonization by breast cancer cells, while treatment with exosomes derived from LSD1 KD cells decreased the expression of the ZO-1 and occludin, leading to increased vascular permeability. The LSD1 KD reduced the expression of circDOCK1, which augmented the levels of miR-1270 in exosomes. And miR-1270 inhibited ZO-1 expression in human endothelial cells, which enhanced their permeability. Our study uncovered a novel mechanism in which the LSD1 promotes the formation of pre-metastatic niches via the regulation of exosomal miRNA.

Targeting SPP1-orchestrated neutrophil extracellular traps-dominant pre-metastatic niche reduced HCC lung metastasis

Background

The mechanisms by which tumor-derived factors remodel the microenvironment of target organs to facilitate cancer metastasis, especially organ-specific metastasis, remains obscure. Our previous studies have demonstrated that SPP1 plays a key role in promoting metastasis of hepatocellular carcinoma (HCC). However, the functional roles and mechanisms of tumor-derived SPP1 in shaping the pre-metastatic niche (PMN) and promoting lung-specific metastasis are unclear.

Methods

Orthotopic metastasis models, experimental metastasis models, CyTOF and flow cytometry were conducted to explore the function of SPP1 in shaping neutrophil-dominant PMN and promoting HCC lung metastasis. The main source of CXCL1 in lung tissues was investigated via fluorescence activated cell sorting and immunofluorescence staining. The expression of neutrophils and neutrophil extracellular traps (NETs) markers was detected in the lung metastatic lesions of HCC patients and mouse lung specimens. The therapeutic significance was explored via in vivo DNase I and CXCR2 inhibitor assays.

Results

SPP1 promoted HCC lung colonization and metastasis by modifying pulmonary PMN in various murine models, and plasma SPP1 levels were closely associated with lung metastasis in HCC patients. Mechanistically, SPP1 binded to CD44 on lung alveolar epithelial cells to produce CXCL1, thereby attracting and forming neutrophil-abundant PMN in the lung. The recruited neutrophils were activated by SPP1 and then formed NETs-dominant PMN to trap the disseminated tumor cells and promote metastatic colonization. Moreover, early intervention of SPP1-orchestrated PMN by co-targeting the CXCL1-CXCR2 axis and NETs formation could efficiently inhibit the lung metastasis of HCC.

Conclusions

Our study illustrates that HCC-lung host cell-neutrophil interactions play important roles in PMN formation and SPP1-induced HCC lung metastasis. Early intervention in SPP1-orchestrated PMN via CXCR2 inhibitor and DNase I is a potential therapeutic strategy to combat HCC lung metastasis.

Targeting SPP1-orchestrated neutrophil extracellular traps-dominant pre-metastatic niche reduced HCC lung metastasis

BACKGROUND

The mechanisms by which tumor-derived factors remodel the microenvironment of target organs to facilitate cancer metastasis, especially organ-specific metastasis, remains obscure. Our previous studies have demonstrated that SPP1 plays a key role in promoting metastasis of hepatocellular carcinoma (HCC). However, the functional roles and mechanisms of tumor-derived SPP1 in shaping the pre-metastatic niche (PMN) and promoting lung-specific metastasis are unclear.

METHODS

Orthotopic metastasis models, experimental metastasis models, CyTOF and flow cytometry were conducted to explore the function of SPP1 in shaping neutrophil-dominant PMN and promoting HCC lung metastasis. The main source of CXCL1 in lung tissues was investigated via fluorescence activated cell sorting and immunofluorescence staining. The expression of neutrophils and neutrophil extracellular traps (NETs) markers was detected in the lung metastatic lesions of HCC patients and mouse lung specimens. The therapeutic significance was explored via in vivo DNase I and CXCR2 inhibitor assays.

RESULTS

SPP1 promoted HCC lung colonization and metastasis by modifying pulmonary PMN in various murine models, and plasma SPP1 levels were closely associated with lung metastasis in HCC patients. Mechanistically, SPP1 binded to CD44 on lung alveolar epithelial cells to produce CXCL1, thereby attracting and forming neutrophil-abundant PMN in the lung. The recruited neutrophils were activated by SPP1 and then formed NETs-dominant PMN to trap the disseminated tumor cells and promote metastatic colonization. Moreover, early intervention of SPP1-orchestrated PMN by co-targeting the CXCL1-CXCR2 axis and NETs formation could efficiently inhibit the lung metastasis of HCC.

CONCLUSIONS

Our study illustrates that HCC-lung host cell-neutrophil interactions play important roles in PMN formation and SPP1-induced HCC lung metastasis. Early intervention in SPP1-orchestrated PMN via CXCR2 inhibitor and DNase I is a potential therapeutic strategy to combat HCC lung metastasis.

Harnessing curcumin and nanotechnology for enhanced treatment of breast cancer bone metastasis

Breast cancer (BC) bone metastasis poses a significant clinical challenge due to its impact on patient prognosis and quality of life. Curcumin (CUR), a natural polyphenol compound found in turmeric, has shown potential in cancer therapy due to its anti-inflammatory, antioxidant, and anticancer properties. However, its metabolic instability and hydrophobicity have hindered its clinical applications, leading to a short plasma half-life, poor absorption, and low bioavailability. To enhance the drug-like properties of CUR, nanotechnology-based delivery strategies have been employed, utilizing polymeric, lipidic, and inorganic nanoparticles (NPs). These approaches have effectively overcome CUR's inherent limitations by enhancing its stability and cellular bioavailability both in vitro and in vivo. Moreover, targeting molecules with high selectivity towards bone metastasized breast cancer cells can be used for site specific delivery of curcumin. Alendronate (ALN), a bone-seeking bisphosphonate, is one such moiety with high selectivity towards bone and thus can be effectively used for targeted delivery of curcumin loaded nanocarriers. This review will detail the process of bone metastasis in BC, elucidate the mechanism of action of CUR, and assess the efficacy of nanotechnology-based strategies for CUR delivery. Specifically, it will focus on how these strategies enhance CUR's stability and improve targeted delivery approaches in the treatment of BC bone metastasis.

Nasal mRNA Nanovaccine with Key Activators of Dendritic and MAIT Cells for Effective Against Lung Tumor Metastasis in Mice Model

Background

Lung metastasis is a leading cause of cancer-related death. mRNA-based cancer vaccines have been demonstrated to be effective at inhibiting tumor growth. Intranasal immunization has emerged as a more effective method of inducing local immune responses against cancer cells in the lungs.

Methods

An innovative layered double hydroxide- and 5-OP-RU-based mRNA nanovaccine (Mg/Al LDH-5-OP-RU/mRNA) was synthesized via coprecipitation. The particle size distribution and zeta potential were measured, and the nanovaccine was observed by transmission electron microscopy. The functions and properties of the nanovaccine were evaluated via an mRNA-targeted delivery assay and measurement of dendritic cell (DC) and mucosa-associated invariant T (MAIT) cell maturation and activation. In addition, the cytotoxicity, antigen-specific T cell activation, cytokines, protective ability, and therapeutic ability of the nanovaccine were assessed in a mouse tumor model. Further, the immune cell composition was evaluated in tumors.

Results

The Mg/Al LDH-5-OP-RU/mRNA nanovaccine was efficiently delivered into lung-draining mediastinal lymph nodes (MLNs), and it activated dendritic cells (DCs) and mucosa-associated invariant T (MAIT) cells after intranasal administration. Moreover, the optimized dual-activating mRNA nanovaccine efficiently transfected DC cells and expressed antigen proteins in DC cells. An HPV-associated tumor model revealed that the intranasal delivery of the Mg/Al LDH-5-OP-RU/E7 mRNA nanovaccine significantly prevented the lung metastasis of tumors and had a therapeutic effect on established metastatic tumor nodules in the lungs. Mechanistically, the enhanced activation of DC and MAIT cells induced by the Mg/Al LDH-5-OP-RU/E7 mRNA nanovaccine increased the production of immune-stimulating cytokines and decreased the secretion of immunosuppressive cytokines, which led to the expansion and activation of memory T cells targeting the E7 antigen, a reduction in the population of neutrophils, and differentiation of tumor -associated macrophages to the M1 phenotype in the lungs.

Conclusion

These results highlight the potential of the innovative nasal mRNA nanovaccine for both preventing and treating tumor metastasis in the lungs.

Harnessing Gene Editing Technology for Tumor Microenvironment Modulation: An Emerging Anticancer Strategy

Cancer is a multifaceted disease influenced by both intrinsic cellular traits and extrinsic factors, with the tumor microenvironment (TME) being crucial for cancer progression. To satisfy their high proliferation and aggressiveness, cancer cells always plunder large amounts of nutrients and release various signals to their surroundings, forming a dynamic TME with special metabolic, immune, microbial and physical characteristics. Due to the neglect of interactions between tumor cells and the TME, traditional cancer therapies often struggle with challenges such as drug resistance, low efficacy, and recurrence. Importantly, the development of gene editing technologies, particularly the CRISPR-Cas system, offers promising new strategies for cancer treatment. Combined with nanomaterial strategies, CRISPR-Cas technology exhibits precision, affordability, and user-friendliness with reduced side effects, which holds great promise for profoundly altering the TME at the genetic level, potentially leading to lasting anticancer outcomes. This review will delve into how CRISPR-Cas can be leveraged to manipulate the TME, examining its potential as a transformative anticancer therapy.

The missing link between cancer stem cells and immunotherapy

Cancer stem cells (CSCs) are cancer cells that can self-renew and give rise to tumors. The multipotency of CSCs enables the generation of diverse cancer cell types and their potential for differentiation and resilience against chemotherapy and radiation. Additionally, specific biomarkers have been identified for them, such as CD24, CD34, CD44, CD47, CD90, and CD133. The CSC model suggests that a subset of CSCs within tumors is responsible for tumor growth. The tumor microenvironment (TME), including fibroblasts, immune cells, adipocytes, endothelial cells, neuroendocrine (NE) cells, extracellular matrix (ECM), and extracellular vesicles, has a part in shielding CSCs from the host immune response as well as protecting them against anticancer drugs. The regulation of cancer stem cell plasticity by cancer-associated fibroblasts (CAFs) occurs through specific signaling pathways that differ among various types of cancer, utilizing the IGF-II/IGF1R, FAK, and c-Met/FRA1/HEY1 signaling pathways. Due to the intricate dynamics of CSC proliferation, controlling their growth necessitates innovative approaches and much more research. Our current review speculates an outline of how the TME safeguards stem cells, their interaction with CSCs, and the involvement of the immune and inflammatory systems in CSC differentiation and maintenance. Several technologies have the ability to identify CSCs; however, each approach has limitations. We discuss how these methods can aid in recognizing CSCs in several cancer types, comprising brain, breast, liver, stomach, and colon cancer. Furthermore, we explore different immunotherapeutic strategies targeting CSCs, including stimulating cancer-specific T cells, modifying immunosuppressive TMEs, and antibody-mediated therapy targeting CSC markers.

Induced collagen type-I secretion by hepatocytes of the melanoma liver metastasis is associated with a reduction in tumour-infiltrating lymphocytes

BACKGROUND

Overall patients with melanoma liver metastasis (MLiM) have a dismal prognosis and poor responses to the standard of care treatment. Understanding the role of the tumour microenvironment (TME) is critical for discovering better strategies to overcome intrinsic therapy resistance in MLiM. The aim was to understand the crosstalk signalling pathways between hepatocytes and metastatic melanoma cells in the TME of MLiM.

METHODS

Hepatocytes and melanoma tumour cells of MLiM were assessed using transcriptomic NanoString GeoMx digital spatial profiling (NGDSP) assay. Functional assays were performed using normal hepatocytes and MLiM-derived cell lines. Validation was performed using multiplex immunofluorescence.

RESULTS

In NGDSP analysis adjacent normal hepatocytes (ANH) had higher CXCR4 and COL1A1/2 levels than distant normal hepatocytes (DNH), while melanoma cells had higher TNF-α levels. In vitro, MLiM cell lines released TNF-α which upregulated CXCR4 and CXCL12 levels in ANH. CXCL12 activated CXCR4, which triggered AKT and NFκB signalling pathways. Consequently, AKT signalling induced the upregulation of collagen type I. MLiM were significantly encircled by a shield of collagen, whereas other liver metastases showed reduced levels of collagen. Of all the liver metastasis analyzed, the presence of collagen in melanoma liver metastasis was associated with a reduction in tumour-infiltrating lymphocytes.

CONCLUSIONS

MLiM modified ANH to increase collagen production and created a physical barrier. The collagen barrier was associated with a reduction of immune cell infiltration which could potentially deter MLiM immune surveillance and treatment responses.

HIGHLIGHTS

Spatial analyses of melanoma liver metastasis show that adjacent normal hepatocytes have increased collagen-type I levels. Melanoma liver metastases tumour cells secrete enhanced levels of TNF-α to stimulate CXCR4/CXCL12 upregulation in adjacent normal hepatocytes. Activation of CXCR4 promotes AKT and NF-κB signalling pathways to promote collagen-type I secretion in adjacent normal hepatocytes. Elevated collagen levels were associated with reduced tumour-infiltrating lymphocytes.

Macrophage diversity in cancer dissemination and metastasis

Invasion and metastasis are hallmarks of cancer. In addition to the well-recognized hematogenous and lymphatic pathways of metastasis, cancer cell dissemination can occur via the transcoelomic and perineural routes, which are typical of ovarian and pancreatic cancer, respectively. Macrophages are a universal major component of the tumor microenvironment and, in established tumors, promote growth and dissemination to secondary sites. Here, we review the role of tumor-associated macrophages (TAMs) in cancer cell dissemination and metastasis, emphasizing the diversity of myeloid cells in different tissue contexts (lungs, liver, brain, bone, peritoneal cavity, nerves). The generally used models of lung metastasis fail to capture the diversity of pathways and tissue microenvironments. A better understanding of TAM diversity in different tissue contexts may pave the way for tailored diagnostic and therapeutic approaches.

Extracellular Vesicles as Potential Biomarkers in Addictive Disorders

Small extracellular vesicles (sEVs) and their role in mental and addictive disorders are extremely promising research areas. Because of their small size, sEVs can pass through the blood-brain barrier. The membrane of sEVs contain proteins that protect them against destruction by the organism's immune system. Due to these properties, sEVs circulating in the blood can be used as potential biomarkers of processes occurring in the brain. Exposure to psychoactive substances in vitro and in vivo affects sEV biogenesis and significantly alters the amount of sEVs and chemical composition of their cargo. Based on the published reports, sEVs carry numerous potential biomarkers of addictive pathologies, although the diagnostic significance of these markers still has to be evaluated. A large body of evidence indicates that psychoactive substances influence Rab family GTPases, Toll-like receptors, complement system components, and cytokines. In some studies, the effect of psychoactive substances on sEVs was found to be sex-dependent. It has become commonly accepted that sEVs are involved in the regulation of neuroinflammation and interaction between glial cells and neurons, as well as between peripheral cells and cells of the central nervous system. Here, we formulated a hypothesis on the existence of two mechanisms/stages involved in the effect of psychoactive substances on sEVs: the "fast" mechanism that provides neuroplasticity, and the "slow" one, resulting from the impaired biogenesis of sEVs and formation of aberrant vesicles.

Extravasation of immune and tumor cells from an endothelial perspective

Crossing the vascular endothelium is a necessary stage for circulating cells aiming to reach distant organs. Leukocyte passage through the endothelium, known as transmigration, is a multistep process during which immune cells adhere to the vascular wall, migrate and crawl along the endothelium until they reach their exit site. Similarly, circulating tumor cells (CTCs), which originate from the primary tumor or reseed from early metastatic sites, disseminate using the blood circulation and also must cross the endothelial barrier to set new colonies in distant organs. CTCs are thought to mimic arrest and extravasation utilized by leukocytes; however, their extravasation also requires processes that, from an endothelial perspective, are specific to cancer cells. Although leukocyte extravasation relies on maintaining endothelial impermeability, it appears that cancer cells can indoctrinate endothelial cells into promoting their extravasation independently of their normal functions. In this Review, we summarize the common and divergent mechanisms of endothelial responses during extravasation of leukocytes (in inflammation) and CTCs (in metastasis), and highlight how these might be leveraged in the development of anti-metastatic treatments.

Jiedu recipe, a compound Chinese herbal medicine, suppresses hepatocellular carcinoma metastasis by inhibiting the release of tumor-derived exosomes in a hypoxic microenvironment

OBJECTIVE

Tumor-derived exosomes (TDEs) play crucial roles in intercellular communication. Hypoxia in the tumor microenvironment enhances secretion of TDEs and accelerates tumor metastasis. Jiedu recipe (JR), a traditional Chinese medicinal formula, has demonstrated efficacy in preventing the metastasis of hepatocellular carcinoma (HCC). However, the underlying mechanism remains largely unknown.

METHODS

Animal experiments were performed to investigate the metastasis-preventing effects of JR. Bioinformatics analysis and in vitro assays were conducted to explore the potential targets and active components of JR. TDEs were assessed using nanoparticle tracking analysis (NTA) and Western blotting (WB). Exosomes derived from normoxic or hypoxic HCC cells (H-TDEs) were collected to establish premetastatic mouse models. JR was intragastrically administered to evaluate its metastasis-preventive effects. WB and lysosomal staining were performed to investigate the effects of JR on lysosomal function and autophagy. Bioinformatics analysis, WB, NTA, and immunofluorescence staining were used to identify the active components and potential targets of JR.

RESULTS

JR effectively inhibited subcutaneous-tumor-promoted lung premetastatic niche development and tumor metastasis. It inhibited the release of exosomes from tumor cells under hypoxic condition. JR treatment promoted both lysosomal acidification and suppressed secretory autophagy, which were dysregulated in hypoxic tumor cells. Quercetin was identified as the active component in JR, and the epidermal growth factor receptor (EGFR) was identified as a potential target. Quercetin inhibited EGFR phosphorylation and promoted the nuclear translocation of transcription factor EB (TFEB). Hypoxia-impaired lysosomal function was restored, and secretory autophagy was alleviated by quercetin treatment.

CONCLUSION

JR suppressed HCC metastasis by inhibiting hypoxia-stimulated exosome release, restoring lysosomal function, and suppressing secretory autophagy. Quercetin acted as a key component of JR and regulated TDE release through EGFR-TFEB signaling. Our study provides a potential strategy for retarding tumor metastasis by targeting H-TDE secretion. Please cite this article as: Jia WT, Xiang S, Zhang JB, Yuan JY, Wang YQ, Liang SF, Lin WF, Zhai XF, Shang Y, Ling CQ, Cheng BB. Jiedu recipe, a compound Chinese herbal medicine, suppresses hepatocellular carcinoma metastasis by inhibiting the release of tumor-derived exosomes in a hypoxic microenvironment through the EGFR-TFEB signaling pathway. J Integr Med. 2024; 22(6): 697-709.