Search Results (150)

Bone metastases mark a critical and often terminal phase in cancer progression, where disseminated tumor cells (DTCs) manage to infiltrate and exploit the complex microenvironments of the bone marrow. While most current therapies focus on the well-known late-stage “vicious cycle” of osteolysis, they often overlook the earlier stages, namely, tumor cell colonization and dormancy. During these early phases, cancer cells co-opt hematopoietic stem cell (HSC) niches, using them as sanctuaries for long-term survival. In this review, we bring together emerging insights that highlight a trio of underappreciated cellular players in this metastatic takeover: megakaryocytes, erythroid lineage cells, and perivascular stromal subsets. Far from being passive bystanders, these cells actively shape the metastatic niche. For instance, megakaryocytes and platelets go beyond their role in transport; they orchestrate immune evasion and dormancy through mechanisms such as transforming growth factor-β1 (TGF-β1) signaling and the physical shielding of tumor cells. In parallel, we uncover a distinct “erythroid-immune” axis: here, stress-induced CD71⁺ erythroid progenitors suppress T-cell responses via arginase-mediated nutrient depletion and checkpoint engagement, forming a potent metabolic barrier against immune attack. Furthermore, leptin receptor–positive (LepR⁺) perivascular stromal cells emerge as key structural players. These stromal subsets not only act as anchoring points for DTCs but also maintain them in protective vascular zones via CXCL12 chemokine gradients. Altogether, these findings reveal that the metastatic bone marrow niche is not static; it is a highly dynamic, multi-lineage ecosystem. By mapping these intricate cellular interactions, we argue for a paradigm shift: targeting these early and cooperative crosstalk, whether through glycoprotein-A repetitions predominant (GARP) blockade, metabolic reprogramming, or other niche-disruptive strategies, could unlock new therapeutic avenues and prevent metastatic relapse at its root. Full article

Background: Colorectal cancer (CRC) frequently metastasizes to the liver (CRLM), where M2-polarized macrophages shape an immunosuppressive pre-metastatic niche. The molecular cues driving this polarization remain unclear. Methods and Results: Using integrated transcriptomics, patient cohorts, and mouse models, we investigated the role of tissue inhibitor of metalloproteinases-1 (TIMP1) in CRLM. TIMP1 was consistently overexpressed in CRC tissues and associated with poor overall survival. CRC cells secreted TIMP1 into the tumor microenvironment, where it induced M2-like macrophage polarization and increased the expression of immunosuppressive mediators such as CSF1 and IRF4. In vivo, TIMP1 overexpression enhanced, whereas its knockdown reduced, liver metastatic burden. Immune profiling and depletion experiments indicated that these pro-metastatic effects were largely macrophage-dependent. Mechanistically, TIMP1 engaged CD63/β1-integrin on macrophages, activating AKT/mTOR signaling and stabilizing the M2 phenotype. Conclusions: CRC-derived TIMP1 remodels liver macrophages via the CD63/β1-integrin–AKT/mTOR pathway to promote a hepatic pre-metastatic niche. Pharmacologic inhibition of this signaling axis with the integrin antagonist cilengitide suppressed macrophage M2 markers and liver colonization in mice, supporting TIMP1–integrin signaling as a potential therapeutic target. Full article

The tumor microenvironment (TME) orchestrates tumor growth, immune evasion, and therapeutic response in head and neck squamous cell carcinoma (HNSCC). Current immune checkpoint inhibitors (ICIs) target the programmed death receptor-1/programmed death-ligand 1 (PD-1/PD-L1) axis and improve survival in recurrent, metastatic, and locally advanced HNSCC. Tumor cells produced exosomes directly suppress cytotoxic T-lymphocytes activity by modulating immune checkpoint pathways and disrupting T-cell receptor signaling. Cancer-associated fibroblast-derived exosomes (CAF-Exos) function indirectly by conditioning immune escape and tumor growth. Together, these exosomal populations cooperate to create an immunosuppressive niche that hinders the efficacy of immunotherapies. CAF-Exos induce TME changes that exclude CD8⁺ T-cells, promote regulatory T-cells (Tregs), and upregulate PD-L1 expression in tumor cells. The bidirectional transfer of microRNAs (miRNAs) between tumor cells and CAFs enhances epithelial–mesenchymal transition (EMT), suppresses cytotoxic lymphocytes, and undermines ICI efficacy. This review article summarizes recent publications about plasma-derived exosomes from HNSCC patients. These exosomes carry tumor and immune checkpoint markers, reflect tumor burden and treatment response, and strongly modulate immune cells by suppressing T- and B-cell activity and promoting immunosuppressive macrophages. We encourage functional and biomechanistic future studies in the field of HNSCC that examine how CAF subtypes exosomes achieve an immunoresistant TME. Full article

Bone metastases remain a leading cause of morbidity and mortality in patients with advanced breast, prostate, and lung cancers. A striking clinical feature of bone metastasis is the ability of disseminated tumor cells (DTCs) to persist in a dormant state for years or even decades before reawakening to drive overt disease. While the molecular and microenvironmental cues that induce and maintain dormancy have been increasingly studied, the mechanisms governing dormancy escape remain poorly defined yet are critical for preventing relapse. In this review, we synthesize emerging evidence on how the bone microenvironment orchestrates the transition of dormant tumor cells into proliferative lesions. We discuss how osteoclast-mediated bone resorption liberates growth factors such as TGF-β and IGF-1, fueling reactivation; how loss of osteoblast-mediated quiescence signals disrupts the endosteal niche; and how bone marrow adipocytes provide metabolic support through lipid transfer and adipokine secretion. We highlight the role of immune surveillance in maintaining dormancy and how immunosuppressive myeloid populations, regulatory T cells, and inflammatory triggers, such as neutrophil extracellular traps, promote escape. Additional emphasis is placed on extracellular matrix remodeling, mechanotransduction, angiogenic switching, and systemic factors, including aging, hormonal changes, and sympathetic nervous system activation. We also review epigenetic and metabolic reprogramming events within dormant cells that enable reactivation. Finally, we evaluate therapeutic strategies to sustain dormancy or prevent reawakening, including osteoclast-targeted therapies, immune-modulating approaches, and epigenetic or metabolic interventions. By integrating these insights, we identify key knowledge gaps and propose future directions to intercept dormancy escape and delay or prevent metastatic relapse in bone. Full article

Introduction: Prostate cancer (PC) accounts for around 10% of all cancers worldwide and is the fourth most common neoplasm. Localized PC has high cure rates when diagnosed early, but 35% of patients progress to the metastatic form. The search for new molecular markers, such as microRNAs, is fundamental to improving diagnosis and treatment. The role of miR-10a is controversial between tumor tissues, opening a niche for studies on their role in PC. Objectives: To evaluate the role of miR-10a in metastatic PC cell lines, focusing on the mechanisms of proliferation, migration, and invasion, and to analyze the expression in surgical specimens of localized PC. Methods: Three commercial metastatic PC cell lines were used: LNCaP, DU145 and PC-3. Expression of mimic miR-10a was induced by cell transfection, followed by extraction of miRNA and total RNA. The synthesis of complementary DNA (cDNA) and analysis by real-time PCR enabled the expression of miR-10a and the VEGF, MYC, and HAS3 genes to be assessed. Matrigel, colony formation, invasion, and migration assays were evaluated for the transfected cells. The surgical specimens were used to evaluate the miR-10a expression. Results: Transfected cells with mimic significantly increased the expression of miR-10a in the LNCaP (p = 0.0179), PC-3 (p ≤ 0.001), and DU145 (p ≤ 0.001) cell lines. Transfected cells reduced cell invasion in the PC-3 (p = 0.001) and DU-145 (p = 0.0004) cell lines and decreased cell migration and proliferation. In surgical specimens, miR-10a expression was higher in PC compared to Benign Prostatic Hyperplasia (p = 0.0010). Conclusions: Increased expression of miR-10a affects cell migration, invasion, and proliferation, showing potential as a therapeutic target in treating PC. Full article

Fusobacterium nucleatum is a Gram-negative anaerobe that occupies a central ecological niche in oral biofilms but has emerged as a trans-compartmental pathogen implicated in gastrointestinal and cardiovascular diseases. In inflammatory bowel diseases, Fusobacterium nucleatum adheres to the intestinal epithelium via adhesins such as FadA, disrupts tight junctions, and induces Toll-like receptor–mediated inflammatory cascades, amplifying epithelial permeability and sustaining mucosal inflammation. In colorectal cancer, Fusobacterium nucleatum promotes carcinogenesis through multiple mechanisms, including β-catenin activation, modulation of oncogenic microRNAs, and immune evasion via Fap2–TIGIT signaling, while also fostering a pro-inflammatory and immunosuppressive tumor microenvironment. Its enrichment correlates with advanced tumor stage, chemoresistance, and poor prognosis, underscoring its potential as a biomarker and therapeutic target. Beyond the gut, Fusobacterium nucleatum has been detected in atherosclerotic plaques and endocardial tissues, where it contributes to endothelial dysfunction, foam cell formation, oxidative stress, and plaque instability, thereby linking chronic oral infection with cardiovascular risk. Collectively, evidence suggests that Fusobacterium nucleatum acts as a pathophysiological connector across IBD, CRC, and CVD through conserved mechanisms of adhesion, immune modulation, and inflammation. Understanding these processes provides opportunities for innovative interventions, ranging from targeted antimicrobials and host-directed therapies to dietary and microbiome-based strategies, aimed at mitigating the systemic burden of this organism and improving clinical outcomes across multiple diseases. Full article

Breast cancer (BC) remains one of the most prevalent and life-threatening malignancies worldwide, marked by significant heterogeneity and complex mechanisms of progression. Despite major advances in understanding its molecular and cellular basis, the processes driving tumor progression and metastasis continue to challenge effective treatment. Among the emerging research areas, extracellular vesicles (EVs) have gained considerable attention for their key role in intercellular communication and their contribution to cancer biology. In BC, tumor cell-derived EVs are implicated in multiple processes that promote disease progression, including tumor growth, remodeling of the tumor microenvironment, and facilitation of metastasis. By transferring oncogenic signals to recipient cells, EVs critically shape the metastatic niche and support the spread of cancer cells to distant organs. Recent studies highlight the diverse functions of BC-derived EVs in modulating immune responses, inducing angiogenesis, and enhancing cancer cell invasiveness. This review explores the role of BC-derived EVs in tumor progression and metastasis. We discuss their molecular composition, mechanisms of action, and impact on the tumor microenvironment, aiming to provide insights into their role in BC pathophysiology and discuss potential clinical applications. A deeper understanding of the complex interplay between EVs and cancer progression may pave the way for innovative strategies to combat BC and improve patient outcomes. Full article

Melanoma is the most aggressive form of skin cancer, and despite significant therapeutic advances over the past decade, a substantial number of patients still progress to a fatal outcome. The initiation and progression of melanoma are strongly influenced by interactions between melanoma cells and other components of the tumor microenvironment (TME). In this review, we focus on the interplay between fibroblasts resident in the tumor microenvironment and tumor cells. In particular, we examine the molecular mechanisms through which melanoma cells induce the transformation of resident fibroblasts into their active form, known as cancer-associated fibroblasts (CAFs). We also explore the role of CAFs in shaping the melanoma microenvironment (MME) and in organizing the pre-metastatic niche, a specialized microenvironment that forms in distant organs or tissues to support the survival and expansion of metastatic melanoma cells. Finally, we discuss emerging therapeutic strategies aimed at disrupting the interactions between CAFs, melanoma cells, and other components of the tumor microenvironment to improve treatment outcomes. Full article

Cancer stem cells (CSCs) are described as a subpopulation of cells with capabilities of self-renewal, chemoresistance, and invasiveness. CSCs reside in tumor niches and can be studied in vitro through their enrichment in spheroids (Stem). Molecular iodine (I₂) induces apoptosis and differentiation in various cancer cells. I₂ can activate peroxisome proliferator-activated receptors type gamma (PPARγ), and its pathways are associated with its oxidant/antioxidant capacity. This work aimed to compare the effect of I₂ supplementation in progenitor and CSC populations with low (MCF-7 and S-K-NAS) and high invasiveness (MDA-MB231 and SK-N-BE2) in mammary and neuroblastoma (NB) cell lines. Results showed that the CSC population enriched by the spheroid culture overexpressed stem messengers CD44, SOX2, and NMYC and exhibited the highest mitochondrial metabolism (membrane mitochondrial potential and O₂⁻). The presence of I₂ increases PPARγ expression and induces apoptosis through the Bax/Bcl2 index in all populations but silences NMYC expression and reduces mitochondrial metabolism in Stem NB. I₂ also enhances the expression of nuclear erythroid factor 2 (Nrf2) in all populations, but the target antioxidant superoxide dismutase 2 (SOD2) is only elevated in progenitor cells. In contrast, the mitophagy inductors PTEN-induced putative kinase 1 (Pink1) and microtubule-associated protein1 light chain3 alpha (LC3) were overexpressed in Stem populations. I₂-preselected SK-N-BE2 populations exhibited minor implantation and invasion capacities in the in vivo zebrafish model. These data indicate that I₂ interferes with viability, implantation, and invasion capacity in all cell lines, but the molecular mechanisms vary depending on the progenitor or Stem condition. Full article

Merkel cell carcinoma (MCC) is a rare but aggressive neuroendocrine skin cancer, driven by either Merkel cell polyomavirus (MCPyV) integration or ultraviolet (UV)-induced mutations. In MCPyV-positive tumors, viral T antigens inactivate tumor suppressors pRb and p53, while virus-negative MCCs harbor UV-induced mutations that activate similar oncogenic pathways. Key signaling cascades, including PI3K/AKT/mTOR and MAPK, support tumor proliferation, survival, and resistance to apoptosis. Histologically, MCC consists of small round blue cells with neuroendocrine features, high mitotic rate, and necrosis. The tumor microenvironment (TME) plays a central role in disease progression and immune escape. It comprises a mix of tumor-associated macrophages, regulatory and cytotoxic T cells, and elevated expression of immune checkpoint molecules such as PD-L1, contributing to an immunosuppressive niche. The extracellular matrix (ECM) within the TME is rich in proteoglycans, collagens, and matrix metalloproteinases (MMPs), facilitating tumor cell adhesion, invasion, and interaction with stromal and immune cells. ECM remodeling and integrin-mediated signaling further promote immune evasion and therapy resistance. Although immune checkpoint inhibitors targeting PD-1/PD-L1 have shown promise in treating MCC, resistance remains a major hurdle. Therapeutic strategies that concurrently target the TME—through inhibition of ECM components, MMPs, or integrin signaling—may enhance immune responses and improve clinical outcomes. Full article

Research on viper venom has expanded into diverse medical applications, including cancer treatment. This study investigates the potential of Vipera ammodytes venom in oncology, evaluating its cytotoxicity and chemosensitising effects on malignant melanoma cells. Proteomic analysis identified 125 proteins in the venom, with Phospholipases A2, C-type lectins, and metalloproteinases among the most abundant components. These proteins are associated with cytotoxic, anti-proliferative, and tumor-inhibiting properties. Three melanoma cell lines (M001, Me501, and A375) were used to assess venom cytotoxicity. The IC50 values demonstrated consistent venom sensitivity across cell lines (approximately 1.1 µg/mL). Combined treatment with venom and cisplatin significantly increased the cytotoxicity compared to single-agent treatments. Notably, venom enhanced the sensitivity of cisplatin in resistant cell lines (M001 and Me501), increasing cell mortality by up to 40%. The A375 cell line, inherently more sensitive to cisplatin, exhibited additional cytotoxic effects only at higher venom doses. The morphological changes observed under microscopy confirmed venom-induced cellular changes, further supporting its potential as an anti-cancer agent. The selective targeting of melanoma cells by venom components, particularly in muscle-associated metastases, suggests a unique therapeutic niche. While cisplatin was chosen for this pilot study due to its established cytotoxicity, future research will explore venom combinations with contemporary treatments such as immunotherapy and targeted therapies. Although preliminary, these findings provide a foundation for integrating venom-based strategies into advanced melanoma protocols, aiming to improve outcomes in resistant or metastatic cases. Full article

Glioblastoma (GB) is one of the most aggressive and treatment-resistant cancers due to its complex tumor microenvironment (TME). We previously showed that GB progression is dependent on the aberrant induction of chaperone-mediated autophagy (CMA) in pericytes (PCs), which promotes TME immunosuppression through the PC secretome. The secretion of extracellular matrix (ECM) proteins with anti-tumor (Lumican) and pro-tumoral (Osteopontin, OPN) properties was shown to be dependent on the regulation of GB-induced CMA in PCs. As biomarkers are rarely studied in TME, in this work, we aimed to validate Lumican and OPN as prognostic markers in the perivascular areas of the peritumoral niche of a cohort of GB patients. Previously, we had validated their expression in GB xenografted mice presenting GB infiltration (OPN) or GB elimination (Lumican) dependent on competent or deficient CMA PCs, respectively. Then, patient sample classification by GB infiltration into the peritumoral brain parenchyma was related to GB-induced CMA in microvasculature PCs, analyzing the expression of the lysosomal receptor, LAMP-2A. Our results revealed a correlation between GB-induced CMA activity in peritumoral PCs and GB patients’ outcomes, identifying three degrees of severity. The perivascular expression of both immune activation markers, Iba1 and CD68, was related to CMA-dependent PC immune function and determined as useful for efficient GB prognosis. Lumican expression was identified in perivascular areas of patients with less severe outcome and partially co-localizing with PCs presenting low CMA activity, while OPN was primarily found in perivascular areas of patients with poor outcome and partially co-localizing with PCs presenting high CMA activity. Importantly, we found sex differences in the incidence of middle-aged patients, being significantly higher in men but with worse prognosis in women. Our results confirmed that Lumican and OPN in perivascular areas of the GB peritumoral niche are effective predictive biomarkers for evaluating prognosis and monitoring possible therapeutic immune responses dependent on PCs in tumor progression. Full article

Background: Peritoneal metastasis (PM) remains a major challenge in patients with gastric cancer (GC) and occurs preferentially in adipose-rich organs, such as the omentum. Adipose-derived stem cells (ASCs) may influence cancer behavior. This study aimed to investigate whether ASCs isolated from the omentum can act as progenitors of cancer-associated fibroblasts (CAFs) and analyze their effects on the cancer stem cell (CSC) niche and the treatment resistance of GC cells. Methods: ASCs were isolated from the human omentum and their cellular characteristics were analyzed during co-culturing with GC cells. Results: ASCs express CAF markers and promote desmoplasia in cancer stroma in a mouse xenograft model. When co-cultured with GC cells, ASCs enhanced the sphere-forming efficiency of MKN45 and MKN74 cells. ASCs increased IL-6 secretion and enhanced the expression of Nanog and CD44v6 in GC cells; however, these changes were suppressed by the inhibition of IL-6. Xenograft mouse models co-inoculated with MKN45 cells and ASCs showed enhanced CD44v6 and Nanog expression and markedly reduced apoptosis induced by 5-FU treatment. Conclusion: This study improves our understanding of ASCs’ role in PM treatment resistance and has demonstrated the potential for new treatment strategies targeting ASCs. Full article

Liver metastases frequently occur in pancreatic and colorectal cancer. Their development is promoted by tumor-derived exosomes with the integrin α_Vβ₅ on their membrane. This integrin directs exosomes to the liver, where they promote a TGF-β-dependent pre-metastatic niche. We proposed the development of α_Vβ₅⁺ exosomes to deliver anti-TGF-β therapy to the liver. This study demonstrates that the overexpression of α_Vβ₅ in 293T cells allows its transfer to the secreted exosomes. α_Vβ₅ overexpression increases exosome delivery to the liver, and α_Vβ₅⁺ exosomes accumulate more in the liver compared to the lungs, kidneys, and brain in mice. We then sought 293T cells to directly produce and load an anti-TGF-β agent in their exosomes. First, we transduced 293T cells to express shRNAs against Tgfb1; however, the exosomes isolated from these cells did not knock down Tgfb1 in treated macrophages in vitro. However, when 293T expressed an mRNA coding a soluble form of betaglycan (sBG), a TGF-β inhibitor, this mRNA was detected in the isolated exosomes and the protein in the conditioned media of macrophages treated in vitro. In turn, this conditioned media decreased the TGF-β-induced phosphorylation of SMAD2/3 in hepatic cells in vitro. Our findings suggest that α_Vβ₅⁺ exosomes could serve as nanocarriers for liver-targeted anti-TGF-β therapies. Full article

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. Full article