Prostate cancer is the most diagnosed cancer in men and remains a leading cause of cancer related mortality worldwide. A deeper understanding of the cellular and molecular mechanisms that drive prostate cancer progression is essential for improving patient management and identifying new therapeutic targets. Endosomes serve as central hubs for immune function, nutrient sensing, inflammation and signal transduction, and their dysregulation may be central to prostate cancer pathogenesis. Here, we have focused on the early endosome adaptor protein Appl1, investigating the mechanistic links to androgen and leptin biology/signaling that are recognized hallmarks of prostate cancer biology. Appl1 expression increased with Gleason grade in tissue samples from patients with prostate cancer and had an altered cellular location in malignant androgen sensitive prostate cancer cells. Androgen stimulation modulated the expression of endosomal trafficking machinery to alter the spatial temporal distribution and function of Appl1. Appl1 co-located with the leptin receptor, while knockdown of either APPL1 or the myosin motor MYO6 resulted in attenuated Akt signaling following leptin stimulation. Mass spectrometry analysis revealed serine 401 phosphorylation of Appl1 in malignant androgen insensitive PC-3 and non-malignant PNT1a cells, but not in malignant androgen sensitive LNCaP prostate cells. Our findings indicated that androgens alter Appl1 trafficking to increase leptin signaling, providing a potential mechanistic link between altered spatiotemporal endosome biology and prostate cancer disease progression.
Cajal-Retzius neurons (CRN) represent an early-born transient neuronal population in the mammalian neocortex. They are best known for secreting reelin, which is essential for neuronal migration and layer formation in the developing cortex. However, their functional integration into developing cortical circuits and their contribution to early network dynamics have been poorly understood. In this study, we investigated the structural and functional integration of CRN into developing neocortical networks with immunohistochemistry, three-dimensional reconstruction of GABAergic inputs, extracellular electrophysiology and calcium imaging. In addition, multiplexed FISH was used to determine the expression levels of the chloride transporters NKCC1 and KCC2 in CRN at different postnatal stages. Finally, we employed optogenetic stimulation to assess the functional and developmental consequences of CRN activation. We found that CRN receive dense dendritic GABAergic synaptic inputs at early postnatal stages. Functional analyses revealed that a substantial fraction of CRN is spontaneously active, and that their activity is synchronized with both CRN and non-CRN neurons. At the molecular level, they display a persistent NKCC1-dominant expression profile. This profile can contribute to the excitatory GABA responses, but also affect their cell death, as chronic blockade of NKCC1 was associated with reduced CRN loss in vitro. Acute optogenetic activation of CRN at early stages increased network excitability in organotypic neocortical cultures and induced stimulus-evoked field responses, while chronic activation at later time points accelerated CRN loss. Overall, these findings demonstrate that, during development, dense GABAergic input connectivity, coupled with the putative excitatory action of GABA, can engage CRN in early network activity. Furthermore, not only do CRN actively participate in early immature circuits, but their activity also amplifies spontaneous network dynamics and contributes to their own transience, highlighting a potential novel functional role of CRN during neocortical development.
Vesicular membrane trafficking is central to eukaryotic homeostasis, governing receptor downregulation, lysosomal degradation, and intercellular communication via exosomes. These processes are classically explained by SNARE-mediated fusion and ESCRT-dependent membrane remodeling, which together define current models of vesicle biogenesis and multivesicular body (MVB) formation. Recent high-resolution cryo-electron tomography of intact mammalian cells has identified a structurally distinct membrane-associated assembly termed the hemifusome. Hemifusomes consist of two heterotypic vesicles connected by a persistent hemifusion diaphragm ( 160 nm in diameter) and feature a 42 nm proteolipid nanodroplet (PND) localized at the diaphragm rim. This architecture expands current views of hemifusion intermediates and raises the possibility of an alternative mode of endosomal membrane organization distinct from canonical ESCRT-mediated processes. However, the molecular composition, biogenesis, and regulatory mechanisms of this system remain undefined. Here, we provide the first integrated synthesis of hemifusome and PND biology, consolidating structural, biophysical, and mechanistic observations within the context of endosomal trafficking. We compare this emerging framework with ESCRT-mediated intraluminal vesicle formation, highlighting both shared features and key mechanistic gaps. We further examine preliminary and largely correlative links to neurodegenerative and lysosomal storage disorders, while emphasizing the absence of direct causal evidence. Given that this field currently rests on a single primary research report, we deliberately separate this evidence-based structural synthesis from more speculative functional, disease-related, and translational extensions, which are presented as explicit future perspectives rather than established conclusions. Finally, we outline unresolved questions, including PND molecular identity, determinants of hemifusion diaphragm organization and stability, and the temporal sequence of hemifusome assembly and remodeling. Together, these findings position hemifusomes as a potentially distinct structural state within the endosomal network, warranting systematic molecular and functional investigation.
Inflammatory bowel disease (IBD) is characterized by oxidative stress and intractable inflammation. Current therapeutic strategies are far from satisfactory because of its not fully understood pathogenesis. M2 macrophages can promote inflammation resolution and tissue repair, and are attractive therapeutic targets of IBD. However, the intrinsic nature of redox regulation of M2 macrophages in IBD is still elusive. DSS-induced murine colitis recovery model and GEO data suggest that glutaredoxin 1 (Grx1) might be the main redox modulator of macrophages in IBD. Grx1 is the main enzyme negatively catalyzing ROS-elicited protein glutathionylation. Depletion of Grx1 delays colitis recovery, while recombinant Grx1 protein treatment benefits colitis recovery, with decreased glutathionylation and increased M2 macrophages. Grx1-deficient IL-4-polarized macrophages show reduced pro-repair effects on injured intestinal epithelial tight junctions, impaired efferocytosis, and compromised maintenance of the M2-polarized state. Mechanistically, STAT6, a pivotal transcription factor in M2 macrophages, is proved to be the main target of Grx1 and glutathionylation. Grx1 disruption decreases nuclear translocation of STAT6 in macrophages, while mutation of modified cysteine in STAT6 displays reverse effect. Finally, Grx1-STAT6 signaling is verified in colitis recovery models. Our results reveal Grx1/glutathionylation as crucial negative redox regulatory mechanisms of M2 macrophages in IBD, which exhibits promising therapeutic potential of IBD.
Extracellular vesicles are emerging regulators of intercellular signalling in the nervous system, including mechanisms controlling sensory neuron excitability and pain processing. Marsili syndrome, a rare condition characterized by congenital pain insensitivity, provides a unique human model for investigating these pathways. Here, we show that urinary small extracellular vesicles (sEVs) derived from Marsili subjects reduce the responsiveness in differentiated sensory-like F-11 neurons. Marsili sEVs exhibited reduced size, comparable particle concentration, and a distinct microRNA cargo characterized by increased levels of miR-135a-5p and miR-138-5p and reduced miR-183 expression. Functionally, Marsili sEVs attenuated membrane depolarization and intracellular Ca²⁺ influx following inflammatory stimulation and KCl activation, indicating reduced responsiveness in differentiated F-11 cells. These effects were associated with marked downregulation of the potassium channel modulatory subunit KCNV1. Overall, our findings suggest that urinary sEVs from individuals with Marsili syndrome may contribute to the regulation of sensory neuron-like responsiveness by transferring bioactive molecular cargo. These findings identify urinary sEVs as candidate modulators of neuronal signalling that warrant further investigation in primary neurons and in vivo models.
Vesicle trafficking is a core process for cellular material exchange and signal transduction, and its precise execution depends critically on the spatiotemporal coordination of regulatory molecules. In recent years, liquid–liquid phase separation (LLPS) and the resulting biomolecular condensates have been proposed as a mesoscale organizing principle within cells. This Review systematically surveys the emerging roles of LLPS in vesicle trafficking, proceeding from the physicochemical properties of molecular condensates. We focus on three major aspects: how membrane-associated phase separation lowers the energetic barriers to membrane bending and fusion through wetting, interfacial tension, and mesoscale assembly; how condensates act as molecular dispatchers to mediate short-distance vesicle transport, stress-induced flux regulation, and membrane identity switching; and how aberrant condensate behavior represents a shared mechanism in neurodegenerative diseases, viral infections, and cancer, with targeting condensate material states offering a new class of therapeutic strategies.
Human pluripotent stem cell-derived dopaminergic neurons have become central platforms for Parkinson’s disease (PD) modeling and regenerative medicine. Current differentiation systems can efficiently generate TH+/FOXA2+/LMX1A+ ventral midbrain-like populations. Although canonical markers remain important components of dopaminergic validation, the field increasingly complements them with single-cell profiling, developmental reference mapping, functional assessment, and transplantation-based evaluation. Nevertheless, marker-positive phenotypic resemblance alone may inadequately capture the full multidimensional identity of substantia nigra pars compacta neurons. Recent single-cell, developmental, and organoid studies indicate that human dopaminergic neurons exist across highly specialized multidimensional states shaped by developmental trajectory, epigenetic regulation, metabolic adaptation, biological aging, and ecosystem-level interactions. On the basis of these observations, we hypothesize that some current in vitro systems may generate neurons with incomplete or context-dependent identity because of accelerated differentiation, strong exogenous patterning, resetting of age-associated features, incomplete metabolic maturation, and the absence of supporting cells and tissue-derived signals. We distinguish these experimentally observed limitations from their conceptual interpretation and propose a testable framework for evaluating dopaminergic identity across developmental, molecular, metabolic, functional, aging-related, and environmental dimensions. This framework identifies improved maturation, representation of biological age, metabolic resilience, and multicellular context as priorities for PD modeling and regenerative neuroscience.
Osteoarthritis (OA) is a progressive whole-joint disease in which cartilage degeneration remains a central pathological event. Mitochondrial dysfunction and endoplasmic reticulum (ER) stress are prominent features of chondrocyte dysfunction, but how these processes are coordinated across organelles remains incompletely understood. Mitochondria–endoplasmic reticulum contacts (MERCs) are dynamic nanoscale interfaces that support Ca2+ transfer, lipid exchange, proteostasis, mitochondrial dynamics, and organelle quality control. In chondrocytes, MERC remodeling may coordinate localized ER-to-mitochondria Ca2+ transfer with mitochondrial metabolic support and ER proteostasis during physiological adaptation or transient stress. When mechanical or inflammatory stress persists, sustained Ca2+ transfer and reciprocal signaling between reactive oxygen species and unfolded protein response pathways may exceed cellular compensatory capacity, thereby favoring mitochondrial permeability transition, mitochondrial damage, mitochondrial DNA release, and inflammatory or senescence-associated responses. This proposed loss of compensatory control may mark the transition from adaptive coupling to self-reinforcing pathological amplification, although direct evidence for this transition in adult articular chondrocytes is still lacking. This review summarizes the molecular organization and homeostatic functions of MERCs and evaluates their possible involvement in extracellular matrix (ECM) imbalance, Ca2+ dysregulation, oxidative stress, senescence, inflammation, and persistent ER stress in OA. It also reviews therapeutic strategies that modulate MERC-associated pathways while distinguishing direct contact-specific evidence from findings inferred from broader mitochondrial or ER biology and from observations extrapolated from non-chondrocyte or non-articular cartilage models. Current evidence supports a MERC-centered framework as an emerging and testable model of chondrocyte dysfunction rather than a validated central driver or established therapeutic target in OA. Defining the timing, direction, and functional consequences of MERC remodeling in primary adult articular chondrocytes, cartilage explants, in vivo OA models, and human tissues will be essential for determining the causal and therapeutic relevance of this interface.
Ferroptosis is an iron-dependent form of regulated cell death, which is manifested by the lethal accumulation of lipid peroxides. While it is considered a promising strategy for the elimination of apoptosis-resistant cancer cells, growing evidence highlights the dual role of ferroptosis within the tumor microenvironment (TME), affecting both cancer and immune cells. This review integrates tumor- and immune-cell ferroptosis within a three-layer framework comprising membrane lipid composition, antioxidant capacity, and microenvironmental pressure. We discuss how these layers interact to establish distinct ferroptosis thresholds across malignant and cytotoxic T-cell compartments. We highlight that cytotoxic CD8+ T cells and chimeric antigen receptor T cells may be particularly vulnerable to ferroptotic stress as a result of activation-induced metabolic reprogramming and the hostile, nutrient-deprived conditions of the TME. Furthermore, we discuss the immunomodulatory consequences of ferroptosis, including immunogenic and immunosuppressive mediators that can either ignite or stifle antitumor immunity. Lastly, we consider potential approaches that may leverage tumor ferroptosis while preserving T-cell function through tumor-directed ferroptosis induction and reinforcement of antioxidant defenses in engineered T cells. We propose that the ferroptosis axis may play a role in shaping the tumor–immune interface. Differential modulation of ferroptosis in tumor and immune cells could inform future strategies to address resistance to immune checkpoint blockade and improve the efficacy of adoptive cell therapies, although such approaches remain largely experimental and their clinical benefit has yet to be established.
Degenerative bone and joint diseases (DBJDs), including osteoporosis (OP), osteoarthritis (OA), and intervertebral disc degeneration (IVDD), are chronic age-related disorders characterized by progressive destruction of bone and joint tissues and loss of function, posing a heavy global health burden. Emerging evidence indicates that iron dyshomeostasis, chronic lipid peroxidation, and cellular senescence are common pathological features shared by these diseases. The newly discovered concept of ferro-aging—a non-lethal, persistent cellular state driven by sub-lethal lipid peroxidation that leads to cellular dysfunction and a senescence-associated secretory phenotype (SASP)—provides a unified mechanistic framework linking iron metabolism to age-related degeneration. This review systematically summarizes the molecular basis of ferro-aging, with a focus on the central role of ACSL4 in promoting membrane lipid remodeling and sustaining chronic lipid peroxidation. We discuss how ACSL4-associated ferro-aging contributes to the pathogenesis of OP, OA, and IVDD by disrupting local microenvironmental homeostasis, driving metabolic reprogramming, amplifying inflammatory SASP signaling, and impairing the function of key cell types such as osteoblasts (OBs), chondrocytes, and nucleus pulposus cells (NPCs). The differential response to the same ferro-aging program across different tissues determines the distinct clinical phenotypes of these diseases. Finally, we highlight potential intervention strategies targeting the ACSL4-ferro-aging axis and future research directions, offering new insights for the precision treatment of degenerative bone and joint diseases.
Advanced osteosarcoma (OS) remains a clinical challenge due to its aggressive behavior and poor prognosis. Cancer-associated fibroblasts (CAFs) have been shown to contribute to tumor progression, but the tumor–CAF crosstalk in OS is still poorly defined. Elucidating these interactions could reveal novel therapeutic targets. Human OS surgical samples and cell lines were implanted into immunocompromised mice to generate 10 patient-derived (PDXs) and 10 cell line-derived xenografts (CDXs), respectively. RNA-sequencing was performed on the xenografts to distinguish murine stromal from human tumor transcripts. Stromal subpopulation metagenes and matched tumor-stroma ligand-receptor pairs were analyzed. The expression and roles of the candidate ligands were validated using histological analyses, RT-qPCR, Western blot, ELISA, proliferation, migration, invasion, sphere-forming, and RNA silencing assays. Their prognostic relevance was evaluated in human OS samples using a publicly available dataset with clinical annotations and by immunohistochemical analysis. Stromal contribution and tumor growth varied across OS xenografts, with no significant differences between PDXs and CDXs. CAF, white blood cell, and endothelial cell metagenes correlated with stromal content, and myofibroblastic CAFs were the most prevalent subpopulation. The Ephrin A4-Epha2-Bmp4 axis was strongly associated with CAF content. Conditioned medium (CM) from OS cells, which can generate xenografts with high-CAF (HC) content, promoted normal fibroblast (NF) activation and CAF proliferation, migration, and invasion more than CM from low-CAF (LC) cells. Similar effects were observed upon direct treatment with soluble Ephrin A4, but not with CM from Ephrin A4-silenced HC OS cells. In turn, CAF-derived CM or direct treatment with soluble BMP4, but not the CM from BMP4-silenced CAFs, enhanced proliferation, migration, and invasion, and increased stem-like traits in HC OS cells. Ephrin A4 induced EphA2 expression in NFs and BMP4 production in CAFs, whereas BMP4 stimulated Ephrin A4 production in HC OS cells, establishing a tumor-stroma feed-forward loop. The co-expression of human Ephrin A4 and murine BMP4 mRNA was confirmed in HC OS xenografts. Tumor Ephrin A4 and stromal BMP4 were more highly expressed in HC human OS, characterized by higher stromal alpha-smooth muscle actin (αSMA) expression, as well as in OS patients with poor prognosis. Tumor-derived Ephrin A4 and stromal-derived BMP4 generate a feed-forward loop in OS, sustaining tumor aggressiveness. This axis represents a promising therapeutic target that warrants further translational investigations.
Vesicular trafficking is a fundamental mechanism that maintains cellular homeostasis, enables precise material transport, and regulates signal transduction in eukaryotic cells. In immune cells, vesicular trafficking supports dynamic membrane remodeling and activation-dependent vesicle release, while the biological effects of vesicle-associated signals are shaped by cargo composition, cellular origin, and the surrounding immunological context. These features support rapid and context-dependent responses to pathogens, tissue damage, and tumors. Immune cells both generate vesicular outputs and respond to trafficking-dependent changes in receptor localization, cargo composition, and extracellular vesicle signals. This close dependence on trafficking makes immune functions particularly vulnerable to perturbations in the underlying network. This review summarizes the roles of vesicular trafficking in immune regulation and disease. We first outline the specialized features of trafficking in immune cells and their sensitivity to perturbations. We then highlight its key functions in antigen processing and presentation, directional secretion at the immunological synapse, T cell receptor and B cell receptor trafficking, and the spatiotemporal control of inflammatory signaling via compartmentalized endosomal and lysosomal pathways. Finally, we discuss how trafficking defects contribute to immunodeficiency, autoimmunity, chronic inflammation, and tumor immune evasion, and briefly consider emerging therapeutic strategies that target trafficking pathways and extracellular vesicle-based platforms. By linking intracellular sorting decisions with intercellular communication, vesicular trafficking provides a unifying framework for understanding immune regulation and immune-mediated disease.
Human epidermal growth factor receptor 2 (HER2, also known as ERBB2) is aberrantly expressed in multiple malignancies and serves as both a key molecular tumor classification marker and an important therapeutic target. Although monoclonal antibodies, tyrosine kinase inhibitors, and antibody–drug conjugates targeting HER2 have significantly improved patient outcomes, challenges such as treatment resistance and disease relapse remain. To address these unmet clinical needs, circular RNAs (circRNAs) have emerged as key regulators of tumorigenesis, therapeutic resistance, and immune modulation because of their structural stability, tissue specificity, and multifaceted regulatory capabilities. Accumulating evidence indicates that circRNAs derived from the HER2 gene, particularly circular RNA ERBB2 (circERBB2), participate in cancer progression through multiple mechanisms, including microRNA sponging, functional peptide translation (e.g., HER2-103), and rDNA transcriptional regulation. Moreover, circRNAs have been shown to modulate HER2 heterodimerization and downstream signaling activation, thereby promoting tumorigenesis and drug resistance. Beyond their mechanistic roles, circRNAs hold translational potential as diagnostic biomarkers, prognostic indicators, and therapeutic targets, with applications ranging from liquid biopsy-based assays to circRNA-targeted therapies and vaccines. This review summarizes the current advances in circRNA-mediated regulation of HER2 and its heterodimers, focusing on circERBB2, and highlights emerging insights that may help overcome treatment resistance and improve HER2-targeted therapeutic strategies.
Platelet surface receptors play essential roles in cancer progression and metastasis by mediating platelet‒tumor cell interactions. Among these receptors, CLEC-2 and PD-L1 specifically mediate platelet–tumor interactions, whereby CLEC-2 promotes tumor growth and induces epithelial–mesenchymal transition (EMT), while PD-L1 facilitates immune evasion by malignant cells. Additionally, platelet receptors involved in physiological hemostasis, such as αIIbβ3, GPVI, P-selectin, P2Y12, and PAR1, can also facilitate tumor growth and metastatic processes through their interactions with tumor cells. In the early stages of tumor development, GPVI, P-selectin, and P2Y12 receptors are engaged, whereas during angiogenesis, αIIbβ3, P-selectin, P2Y12, and PAR1 receptors become active. In the metastatic phase, αIIbβ3, GPVI, P-selectin, and PAR1 receptors are implicated. Targeting these specific platelet receptors has demonstrated significant therapeutic potential in cancer treatment. Notably, in certain cancers, specific receptor inhibitors targeting CLEC-2, P-selectin, and P2Y12 have been shown to effectively inhibit tumor growth and metastasis, with favorable bleeding risk profiles. In this review, we present a detailed picture of the roles of platelet receptors in cancer progression and metastasis, elucidate the underlying molecular mechanisms, and evaluate the therapeutic potential of receptor-targeted therapies in limiting tumor dissemination.
Radiotherapy (RT) combined with Anti–PD-1 immunotherapy (RT + Anti-PD-1) offers synergistic potential in the treatment of colorectal cancer (CRC). However, RT + Anti-PD-1 often fails to be effective in some patients with CRC, because a subset of tumors exhibits limited responsiveness through mechanisms that remain poorly understood. Here, we identify the complement receptor C5aR1 as a key mediator of reduced sensitivity to RT + Anti-PD-1 in CRC. Transcriptomic profiling revealed a specific upregulation of C5aR1 in tumors treated by RT + Anti-PD-1, and we found its expression was predominantly observed in infiltrating polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs). Functional inhibition of C5aR1 or depletion of PMN-MDSCs restored tumor sensitivity. Mechanistically, RT + Anti-PD-1 elevated C5aR1 expression, promoting C5aR1⁺ PMN-MDSC recruitment and formation of neutrophil extracellular traps (NETs). NETs activated TLR4/9–Traf6 signaling in tumor cells, leading to K63-linked stabilization of hypoxia-inducible factor 1-alpha(HIF-1α), which induced pro-angiogenic and metabolic reprogramming. Collectively, our findings delineate a C5aR1–NET–HIF-1α signaling axis that underlies the reduced therapeutic sensitivity to RT + Anti-PD-1 therapy and highlight this pathway as a potential therapeutic vulnerability in CRC with suboptimal responses to RT + Anti-PD-1.
Cancer is a major cause of mortality in patients with heart failure, and myocardial infarction (MI) has been implicated in promoting tumor progression. Fibroblasts are important stromal components involved in tumor microenvironment formation and pulmonary colonization of tumor cells, but whether myocardial infarction (MI) enhances tumor progression through extracellular vesicles (EVs)-mediated cardiomyocyte–fibroblast communication remains unclear. Tumor growth was assessed in heterotopic mouse models with or without MI. Cardiomyocyte-derived extracellular vesicles (EVs) were characterized by proteomic analysis, and their effects on fibroblast activation, extracellular matrix remodeling, and pulmonary tumor colonization were evaluated using in vitro assays and in vivo mouse models. The functional significance of EVs-associated ANGPTL4 was determined by genetic overexpression and silencing approaches in cardiomyocytes, followed by assessment of fibroblast activation and tumor colonization. A retrospective clinical study compared pulmonary nodule progression and plasma ANGPTL4 levels between MI and non-MI patients. MI promoted tumor growth and fibroblast activation, which were attenuated by EV depletion and partially restored by administration of MI-heart-derived EVs. EVs derived from hypoxic cardiomyocytes enhanced fibroblast activation and were associated with increased pulmonary colonization of tumor cells. Proteomic analysis and functional studies identified EV-associated ANGPTL4 from hypoxic cardiomyocytes as a mediator of fibroblast activation in vitro, and suggested a potential role in pulmonary tumor colonization. Clinically, MI patients exhibited increased pulmonary nodule progression and elevated ANGPTL4 levels in plasma-derived EVs. These findings reveal a previously unrecognized reverse cardio-oncology mechanism in which EVs derived from hypoxic cardiomyocytes were associated with fibroblast activation and tumor growth, and may contribute to pulmonary colonization of tumor cells. This work provides mechanistic insight into how myocardial infarction may enhance tumor progression and increase susceptibility to pulmonary colonization.
Neuroendocrine tumors (NETs) are rare malignancies with a rising incidence and heterogeneous clinical behavior, posing significant challenges to diagnosis and treatment. The urgent need for novel therapeutic strategies is increasingly evident. Filamin A (FLNA), a cytoskeletal protein involved in cancer progression and inflammatory signaling, is cleaved by calpain to generate a 90 kDa C-terminal fragment (FLNACT), whose functional role in NETs remains unclear. The calpain inhibitor calpeptin prevents FLNA cleavage. This study investigates the role of FLNA cleavage and the effects of calpeptin in NET progression using western blotting, RNA sequencing, functional assays, and patient-derived NET organoid models. We found that NET cells express both full-length FLNA and FLNACT, with both localized in the cytoplasm. Calpeptin reduces FLNACT expression and inhibits proliferation and viability in NET models. Its inhibitory effect on cell migration was observed specifically in H727 cells. RNA sequencing identified numerous calpeptin-regulated genes. Comparing the top 500 most significantly altered genes in QGP-1 and H727 cells, we identified 115 genes consistently downregulated and 148 upregulated. Among them, CEACAM5, CDC6, and EGR1 were affected by FLNA silencing in QGP1, while CCNE1, CDC6, ATF3, and EGR1 were influenced in H727. KEGG pathway analysis highlighted cytokine–cytokine receptor interactions in QGP-1 cells, cell cycle regulation in H727 cells, and TGF-β signaling in both models. Calpeptin downregulated TGFBR2 and TGFB3 in both cell lines, with FLNA mediating this effect only in H727 cells. Additionally, it reduced IL5RA in QGP1 and IL17RB in H727, with FLNA involvement limited to H727 cells. Expression of a calpain-resistant FLNA mutant indicated that most transcriptional effects of calpeptin were not fully recapitulated by inhibition of FLNA cleavage alone. In patient-derived NET organoids, calpeptin reduced viability and arrested organoid growth, without inducing a significant increase in caspase-3/7 activity, supporting a predominantly cytostatic rather than pro-apoptotic effect. These findings highlight the complex interplay between calpain activity, FLNA function, and FLNA proteolysis in NETs and support further preclinical investigation of calpain inhibition as a potential therapeutic approach.
The tumor microenvironment (TME) comprises tumor cells, immune cells, fibroblasts, endothelial cells, mesenchymal stem cells, and non-cellular components such as the extracellular matrix and soluble factors. Through intercellular material exchange and signaling, the TME profoundly influences tumor growth, invasion, metastasis, immune evasion, and therapeutic resistance. Among the diverse forms of intercellular communication within the TME, mitochondrial transfer has garnered increasing attention. Here, we synthesize recent advances in mitochondrial transfer within the TME across three levels: transfer mechanisms, biological consequences, and therapeutic implications. We first outline the principal routes of mitochondrial transfer, including tunneling nanotubes, gap junctions, cell fusion, extracellular vesicles, and free mitochondria. We then examine how mitochondrial transfer contributes to tumor progression, therapeutic resistance, and immune regulation. Finally, we discuss the emerging therapeutic opportunities and potential challenges for clinical translation. Deeper insight into mitochondrial transfer within the TME may provide new opportunities for constraining tumor evolution, overcoming treatment resistance, and developing innovative therapies.
Liver Kinase B1 (LKB1) is a master serine/threonine kinase that plays a pivotal role in cell metabolism, proliferation, polarity, and survival. Through the phosphorylation and activation of AMP-activated protein kinase (AMPK) and twelve AMPK-related kinases (ARKs), LKB1 controls complex signalling pathways that are frequently altered in cancer. Increasing evidence demonstrates that ARKs exert context-dependent functions, acting either as tumour suppressors or oncogenes depending on tissue type, genetic landscape, metabolic state and tumour microenvironment. This review provides a comprehensive overview of current knowledge on the structure, regulation, and biological functions of LKB1-activated ARKs, with particular emphasis on their involvement in metabolic reprogramming, cell cycle control, epithelial-mesenchymal transition, invasion, metastasis and cell death. We discuss how ARK deregulation contributes to tumour initiation and progression across multiple cancer types, while emphasizing three crucial aspects of ARK biology. First, we examine the molecular basis of their context-dependent tumour-suppressive or oncogenic functions discussing how these divergent roles influence tumour biology. Second, we summarize recent studies reporting how ARK signalling is rewired by LKB1 mutations, a still unexplored topic. Finally, we discuss emerging preclinical evidence on pharmacological inhibitors targeting specific ARKs, highlighting some therapeutic potential and major challenges that still limit their clinical translation. In particular, the lack of patient stratification based on ARK pathway status represent a major challenge to the successful implementation of ARK-targeted therapies. Given the complexity and tissue-specific behaviour of LKB1–ARK signalling network, a deeper mechanistic understanding is essential to exploit these kinases as therapeutic targets and develop more effective personalized cancer treatments. As key regulators of tumour progression, ARKs are rapidly emerging as promising candidates in precision oncology.
Cellular transdifferentiation enables tumor cells to alter differentiated phenotypes, acquiring capabilities, such as invasiveness, stemness, or drug resistance, in response to microenvironmental stress and therapeutic pressure. This review synthesizes recent findings across solid tumors and hematologic malignancies, elucidating plasticity's pivotal role in carcinogenesis. We delineate the complex molecular networks driving these fate transitions, including the core epithelial plasticity axis (TGF-β/Snail/EZH2/HOTAIR) and the androgen receptor (AR) inhibition-induced neuroendocrine differentiation (NED) pathway prominent in castration-resistant prostate cancer (CRPC). Crucially, the acquisition of cancer stem cells (CSCs) and the activation of stromal cells, such as cancer-associated fibroblasts (CAFs) and mesenchymal stem cells (MSCs), are integral to cancer plasticity within the tumor microenvironment (TME). These cells then co-construct a pro-carcinogenic ecosystem via paracrine signaling and epigenetic reprogramming. Finally, we survey emerging therapeutic strategies targeting these plasticity drivers and associated cellular phenotypes, such as utilizing epigenetic modulators or transdifferentiated cell-based drug delivery systems, offering promising avenues to circumvent therapeutic resistance in advanced cancer.
