技术资料

Tumor-initiating cells (TICs) share features and regulatory pathways with normal stem cells,yet how the stem cell niche contributes to tumorigenesis remains unclear. Here,we identify CXCR4 + macrophages as a niche population enriched in normal mammary ducts,where they promote the regenerative activity of basal cells in response to luminal cell-derived CXCL12. CXCL12 triggers AKT-mediated stabilization of β-catenin,which induces Wnt ligands and pro-migratory genes,enabling intraductal macrophage infiltration and supporting regenerative activity of basal cells. Notably,these same CXCR4 + niche macrophages regulate the tumor-initiating activity of various breast cancer subtypes by enhancing TIC survival and tumor-forming capacity,while promoting early immune evasion through regulatory T cell induction. Furthermore,a CXCR4 + niche macrophage gene signature correlates with poor prognosis in human breast cancer. These findings highlight the pivotal role of the CXCL12-CXCR4 axis in orchestrating interactions between niche macrophages,mammary epithelial cells,and immune cells,thereby establishing a supportive niche for both normal tissue regeneration and mammary tumor initiation. Subject terms: Cancer stem cells,Cancer microenvironment,Tumour immunology View Publication

G protein-coupled receptors (GPCRs) are involved in many fundamental cellular responses such as growth,death,movement,transcription and excitation. Their roles in human stem cell neural specialization are not well understood. In this study,we aimed to identify GPCRs that may play a role in the differentiation of human embryonic stem cells (hESCs) to neural stem cells (NSCs). Using a feeder-free hESC neural differentiation protocol,we found that the expression of several chemokine receptors changed dramatically during the hESC/NSC transition. Especially,the expression of CXCR4 increased approximately 50 folds in NSCs compared to the original hESCs. CXCR4 agonist SDF-1 promoted,whereas the antagonist AMD3100 delayed the neural induction process. In consistence with antagonizing CXCR4,knockdown of CXCR4 in hESCs also blocked the neural induction and cells with reduced CXCR4 were rarely positive for Nestin and Sox1-staining. Taken together,our results suggest that CXCR4 is involved in the neural induction process of hESC and it might be considered as a target to facilitate NSC production from hESCs in regenerative medicine. View Publication

OBJECTIVE: Bone marrow-derived mononuclear cells (BMCs) improve the functional recovery after ischemia. However,BMCs comprise a heterogeneous mixture of cells,and it is not known which cell types are responsible for the induction of neovascularization after cell therapy. Because cell recruitment is critically dependent on the expression of the SDF-1-receptor CXCR4,we examined whether the expression of CXCR4 may identify a therapeutically active population of BMCs. METHODS AND RESULTS: Human CXCR4(+) and CXCR4(-) BMCs were sorted by magnetic beads. CXCR4(+) BMCs showed a significantly higher invasion capacity under basal conditions and after SDF-1 stimulation. Hematopoietic or mesenchymal colony-forming capacity did not differ between CXCR4(+) and CXCR4(-) BMCs. Injection of CXCR4(+) BMCs in mice after induction of hindlimb ischemia significantly improved the recovery of perfusion compared to injection of CXCR4(-) BMCs. Likewise,capillary density was significantly increased in CXCR4(+) BMC-treated mice. Because part of the beneficial effects of cell therapy were attributed to the release of paracrine effectors,we analyzed BMC supernatants for secreted factors. Importantly,supernatants of CXCR4(+) BMCs were enriched in the proangiogenic cytokines HGF and PDGF-BB. CONCLUSIONS: CXCR4(+) BMCs exhibit an increased therapeutic potential for blood flow recovery after acute ischemia. Mechanistically,their higher migratory capacity and their increased release of paracrine factors may contribute to enhanced tissue repair. View Publication

The number of neutrophils in the blood is tightly regulated to ensure adequate protection against microbial pathogens while minimizing damage to host tissue. Neutrophil homeostasis in the blood is achieved through a balance of neutrophil production,release from the bone marrow,and clearance from the circulation. Accumulating evidence suggests that signaling by CXCL12,through its major receptor CXCR4,plays a key role in maintaining neutrophil homeostasis. Herein,we generated mice with a myeloid lineage-restricted deletion of CXCR4 to define the mechanisms by which CXCR4 signals regulate this process. We show that CXCR4 negatively regulates neutrophil release from the bone marrow in a cell-autonomous fashion. However,CXCR4 is dispensable for neutrophil clearance from the circulation. Neutrophil mobilization responses to granulocyte colony-stimulating factor (G-CSF),CXCL2,or Listeria monocytogenes infection are absent or impaired,suggesting that disruption of CXCR4 signaling may be a common step mediating neutrophil release. Collectively,these data suggest that CXCR4 signaling maintains neutrophil homeostasis in the blood under both basal and stress granulopoiesis conditions primarily by regulating neutrophil release from the bone marrow. View Publication

CDK4/6 inhibitors have significantly improved the survival of patients with HR-positive/HER2-negative breast cancer,becoming a first-line treatment option. However,the development of resistance to these inhibitors is inevitable. To address this challenge,novel strategies are required to overcome resistance,necessitating a deeper understanding of its mechanisms. Recent research has identified several dysregulated genes in CDK4/6 inhibitors-resistant breast cancer,but the underlying mechanism is complex due to tumor heterogeneity and warrants further investigation. RNA sequencing and KEGG pathway analysis was carried out to identify the mainly dysregulated genes in CDK4/6 inhibitors-resistant breast cancer cells. The effects of CXCR4 knockdown and overexpression via siRNAs and plasmids transfection were examined by mammosphere formation,RT-qPCR,flow cytometry,MTT and colony formation assays. The regulation mechanisms were analyzed by RT-qPCR,western blotting and immunofluorescence experiments. Mouse xenografts were used to analyze the role of CXCR4 in regulation palbociclib sensitivity in vivo. Additionally,we collected the clinical samples and performed immunohistochemistry to analyze the clinical significance of CXCR4. In our study,we focused on cancer stem cells,a critical contributor to cancer metastasis and therapy resistance,and detected an upregulation of stemness in our established palbociclib-resistant ER-positive breast cancer cells. Additionally,our research pinpointed CXCR4 as a pivotal gene responsible for maintaining cancer stemness and promoting palbociclib resistance. Mechanistically,CXCR4 activates the WNT5A/β-catenin signaling pathway by enhancing the expression of WNT5A and β-catenin,facilitating the nuclear translocation of β-catenin protein. Targeting CXCR4 using siRNAs or small molecular inhibitors effectively reduces cancer stemness and reverses palbociclib resistance both in vitro and in vivo. Clinical sample analysis further underscores the overactivation of the CXCR4/WNT5A/β-catenin axis in palbociclib-resistant breast cancer,suggesting CXCR4 as a potential biomarker for predicting resistance to CDK4/6 inhibitors. Collectively,our study demonstrates that CXCR4 overexpression plays a vital role in maintaining breast cancer stemness and promoting resistance to CDK4/6 inhibitors through the activation of the WNT5A/β-catenin pathway. Targeting CXCR4 may offer a promising therapeutic approach for advanced CDK4/6 inhibitor-resistant ER-positive breast cancer. The online version contains supplementary material available at 10.1186/s13058-025-01965-3. View Publication

Secondary and tertiary lymphoid structures are a critical target of suppression in many autoimmune disorders,protein replacement therapies,and in transplantation. Although antigen-specific regulatory T cells (Tregs),such as chimeric antigen receptor (CAR) Tregs,generally persist longer and localize to target tissues more effectively than polyclonal Tregs in animal models,their numbers still progressively decline over time. A potential approach to maximize Treg activity in vivo is the expression of chemokine receptors such as CXCR5,which would enable localization of a greater number of engineered cells at sites of antigen presentation. Indeed,CXCR5 expression on follicular T helper cells and follicular Tregs enables migration toward lymph nodes,B cell zones,and tertiary lymphoid structures that appear in chronically inflamed non-lymphoid tissues. In this study,we generated human and murine CXCR5 co-expressing engineered receptor Tregs and tested them in preclinical mouse models of allo-immunity and hemophilia A,respectively. Additionally,we engineered a murine CXCR5 co-expressing clotting factor VIII (FVIII) specific T cell receptor fusion construct epsilon (FVIII TRuCe CXCR5) Treg to suppress anti-drug antibody development in a model of FVIII protein replacement therapy for hemophilia A. In vitro,anti-HLA-A2 CXCR5+ CAR-Tregs showed enhanced migratory and antigen-specific suppressive capacities compared to untransduced Tregs. When injected into an NSG mouse model of HLA-A2+ pancreatic islet transplantation,anti-HLA-A2 CXCR5+ CAR-Tregs maintained a good safety profile allowing for long-term graft survival in contrast to anti-HLA-A2 CXCR5+ conventional CAR-T (Tconv) cells that eliminated the graft. Similarly,FVIII TRuCe CXCR5 Treg demonstrated increased in vivo persistence and suppressive capacity in a murine model of hemophilia A. Collectively,our findings indicate that CXCR5 co-expression is safe and enhances in vivo localization and persistence in target tissues. This strategy can potentially promote targeted tolerance without the risk of off-target effects in multiple disease models. View Publication

Neural progenitor cell (NPC) migration is an essential process for brain development,adult neurogenesis,and neuroregeneration after brain injury. Stromal cell-derived factor-1 (SDF-1,CXCL12) and its traditional receptor CXCR4 are well known to regulate NPC migration. However,the discovery of CXCR7,a newly identified CXCL12 receptor,adds to the dynamics of the existing CXCL12/CXCR4 pair. Antagonists for either CXCR4 or CXCR7 blocked CXCL12-mediated NPC migration in a transwell chemotaxis assay,suggesting that both receptors are required for CXCL12 action. We derived NPC cultures from Cxcr4 knockout (KO) mice and used transwell and stripe assays to determine the cell migration. NPCs derived from Cxcr4 KO mice polarized and migrated in response to CXCL12 gradient,suggesting that CXCR7 could serve as an independent migration receptor. Furthermore,Cxcr4 KO NPCs transplanted into the adult mouse striatum migrated in response to the adjacent injection of CXCL12,an effect that was blocked by a CXCR7 antagonist,suggesting that CXCR7 also mediates NPC migration in vivo. Molecular mechanism studies revealed that CXCR7 interact with Rac1 in the leading edge of the polarized NPCs in the absence of CXCR4. Both CXCR7 and Rac1 are required for extracellular signal-regulated kinases (ERK) 1/2 activation and subsequent NPC migration,indicating that CXCR7 could serve as a functional receptor in CXCL12-mediated NPC migration independent of CXCR4. Together these results reveal an essential role of CXCR7 for CXCL12-mediated NPC migration that will be important to understand neurogenesis during development and in adulthood. View Publication

Cyclic adenosine monophosphate (cAMP)-dependent phosphodiesterase (PDE) inhibitors such as pentoxifylline (PTX) suppress cAMP degradation and promote cAMP-dependent signal transduction. PDE inhibitors increase bone formation and bone mass in preclinical models and are used clinically to treat psoriatic arthritis by targeting inflammatory mediators including activated T cells. T cell activation requires two signals: antigen-dependent CD3-activation,which stimulates cAMP production; and CD28 co-stimulation,which downregulates cAMP-signaling,through PDE activation. PDE-inhibitors consequently suppress T cell activation by disrupting CD28 co-stimulation. Interestingly,we have reported that when CD8+ T cells are activated in the absence of CD28 co-stimulation,they secrete Wnt-10b,a bone anabolic Wnt ligand that promotes bone formation. In the present study,we investigated whether the bone anabolic activity of the PDE-inhibitor PTX,has an immunocentric basis,involving Wnt-10b production by CD8+ T cells. When wild-type (WT) mice were administered PTX,biochemical markers of both bone resorption and formation were significantly increased,with net bone gain in the axial skeleton,as quantified by micro-computed tomography ($\mu$CT). By contrast,PTX increased only bone resorption in T cell knockout (KO) mice,causing net bone loss. Reconstituting T cell-deficient mice with WT,but not Wnt-10b knockout (KO) CD8+ T cells,rescued bone formation and prevented bone loss. To study the role of cAMP signaling in Wnt-10b expression,reverse-transcription polymerase chain reaction (RT-PCR) and luciferase-reporter assays were performed using primary T cells. PDE inhibitors intensified Wnt-10b promoter activity and messenger RNA (mRNA) accumulation in CD3 and CD28 activated CD8+ T cells. In contrast,inhibiting the cAMP pathway mediators protein kinase A (PKA) and cAMP response element-binding protein (CREB),suppressed Wnt-10b expression by T cells activated in the absence of CD28 co-stimulation. In conclusion,the data demonstrate a key role for Wnt-10b production by CD8+ T cells in the bone anabolic response to PDE-inhibitors and reveal competing T cell-independent pro-resorptive properties of PTX,which dominate under T cell-deficient conditions. Selective targeting of CD8+ T cells by PDE inhibitors may be a beneficial approach for promoting bone regeneration in osteoporotic conditions. {\textcopyright} 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research. View Publication

Cyclic AMP (cAMP) and cyclic GMP (cGMP) are key second messengers involved in a multitude of cellular events. From the wealth of synthetic analogs of cAMP and cGMP,only a few have been explored with regard to their therapeutic potential. Some of the first-generation cyclic nucleotide analogs were promising enough to be tested as drugs,for instance N(6),O(2)'-dibutyryl-cAMP and 8-chloro-cAMP (currently in clinical Phase II trials as an anticancer agent). Moreover,8-bromo and dibutyryl analogs of cAMP and cGMP have become standard tools for investigations of biochemical and physiological signal transduction pathways. The discovery of the Rp-diastereomers of adenosine 3',5'-cyclic monophosphorothioate and guanosine 3',5'-cyclic monophosphorothioate as competitive inhibitors of cAMP- and cGMP-dependent protein kinases,as well as subsequent development of related analogs,has proven very useful for studying the molecular basis of signal transduction. These analogs exhibit a higher membrane permeability,increased resistance against degradation,and improved target specificity. Furthermore,better understanding of signaling pathways and ligand/protein interactions has led to new therapeutic strategies. For instance,Rp-8-bromo-adenosine 3',5'-cyclic monophosphorothioate is employed against diseases of the immune system. This review will focus mainly on recent developments in cyclic nucleotide-related biochemical and pharmacological research,but also highlights some historical findings in the field. View Publication

A simple and efficient procedure for the construction of bifunctional molecules is described and their use in a variety of applications documented. This procedure is based on our observation that mouse IgG1 monoclonal antibodies,when mixed with equimolar amounts of a high-affinity rat monoclonal antibody specific for mouse IgG1,yield uniform cyclic tetramolecular complexes each consisting of two mouse and two rat antibodies as shown by gel electrophoresis and electron microscopy. When solutions of two mouse antibodies (e.g. a and b) are mixed prior to the formation of complexes with the rat antibody,stable bispecific (a X b) complexes together with monospecific (a X a and b X b) complexes are obtained. Bispecific complexes prepared in this way were able to efficiently bind peroxidase to cell surface antigens,and to bind red blood cells to selected nucleated cell types present in heterogeneous populations. Tetrameric antibody complexes are more easily prepared than bispecific antibodies or bifunctional antibodies produced by transfection of myelomas with recombinant genes. They also have the advantage that the antigen-binding properties of the bivalent monoclonal antibodies are not compromised. Tetrameric antibody complexes thus represent a powerful new type of cross-linking reagent that may have a wide spectrum of applications in biology and medicine. View Publication

Transplantation studies have demonstrated the existence of mammary progenitor cells with the ability to self-renew and regenerate a functional mammary gland. Although these progenitors are the likely targets for oncogenic transformation,correlating progenitor populations with certain oncogenic stimuli has been difficult. Cyclin D1 is required for lobuloalveolar development during pregnancy and lactation as well as MMTV-ErbB2- but not MMTV-Wnt1-mediated tumorigenesis. Using a kinase-deficient cyclin D1 mouse,we identified two functional mammary progenitor cell populations,one of which is the target of MMTV-ErbB2. Moreover,cyclin D1 activity is required for the self-renewal and differentiation of mammary progenitors because its abrogation leads to a failure to maintain the mammary epithelial regenerative potential and also results in defects in luminal lineage differentiation. View Publication

The entry of a cell into mitosis is regulated by an elaborate network of kinases and phosphatases that control both for the timing of cell division and the complete reorganization of the cellular architecture. The mitotic cyclin/Cdks form part of large multiprotein complexes whose other components are only now beginning to be identified. The continuing identification of proteins that contribute to these complexes and changes in the composition of these complexes are likely to give a more integrated view of how mitotic cyclin/Cdk complexes are regulated and how they function-not only to induce mitosis,but also to aid further mitotic progression. Furthermore,assigning specific G2/M functions to distinct mitotic cyclin/Cdk complexes will require the identification of differences in substrate specificities between the mitotic cyclin/Cdk complexes,perhaps in parallel with specific cyclin knockouts in mice. Such investigations will be complicated by potential functional overlap between mitotic cyclin/Cdk complexes in vitro and in vivo. Although cyclin/Cdk1 is thought to be the major kinase that initiates the onset of mitosis,a more complete understanding of how cells move from G2 to a mitotic state will require further identification of kinases operating upstream,downstream and in parallel with Cdk1,their substrates and their relationship with one another during the G2/M transition. View Publication