From gatekeepers to providers: regulation of immune functions by cancer-associated fibroblasts

Multiple instance learning-based prediction of programmed death-ligand 1 (PD-L1) expression from hematoxylin and eosin (H&E)-stained histopathological images in breast cancer

Programmed death-ligand 1 (PD-L1) is an important biomarker increasingly used as a predictive marker in breast cancer immunotherapy. Immunohistochemical quantification remains the standard method for assessment. However, it presents challenges related to time, cost, and reliability. Hematoxylin and eosin (H&E) staining is a routine method in cancer pathology, known for its accessibility and consistently reliability. Deep learning has shown the potential in predicting biomarkers in cancer histopathology. This study employs a weakly supervised multiple instance learning (MIL) approach to predict PD-L1 expression from H&E-stained images using deep learning techniques. In the internal test set, the TransMIL method achieved an area under the curve (AUC) of 0.833, and in an independent external test set, it achieved an AUC of 0.799. Additionally, since RNA sequencing results indicate a threshold that allows for the separation of H&E pathology images, we further validated our approach using the public TCGA-TNBC dataset, achieving an AUC of 0.721. These findings demonstrates that the Transformer-based TransMIL model can effectively capture highly heterogeneous features within the MIL framework, exhibiting strong cross-center generalization capabilities. Our study highlights that appropriate deep learning techniques can enable effective PD-L1 prediction even with limited data, and across diverse regions and centers. This not only underscores the significant potential of deep learning in pathological artificial intelligence (AI) but also provides valuable insights for the rational and efficient allocation of medical resources.

Transplantation of the MSLN-deficient Thymus Generates MSLN Epitope Reactive T Cells to Attenuate Tumor Progression

The development of mesothelin (MSLN) epitope reactive T cells is observed in mice that are immunized with the MSLN vaccine. Engineered T cells expressing MSLN-reactive high-affinity TCR exhibit extraordinary therapeutic effects for invasive pancreatic ductal adenocarcinoma in a mouse model. However, the generation of MSLN-reactive T cells through the introduction of MSLN-deficient thymus and the transplantation of the latter as a cure for cancer treatment have not been tested to date. In the present study, the expression of MSLN was mainly identified in medullary thymic epithelial cells (mTECs) but not in hematopoietic cells, cortical thymic epithelial cells (cTECs), endothelial cells, or fibroblast cells in the thymus. The increasement of activated T cells was observed in MSLN-expressing tumors from MSLN-deficient mice, indicating that MSLN-reactive T cells had developed. Finally, in an AOM-DSS-induced mouse model of colorectal cancer (CRC), transplantation of MSLN-deficient thymus repressed the progression of CRC, accompanied by an increased number of IFNγ-expressing T lymphocytes in the tumors. The data from this study demonstrated that ectopic transplantation of MSLN-deficient thymus induced MSLN-specific antitumor responses to MSLN-expressing tumors, and thus attenuated tumor progression.

Dynamic molecular atlas of cardiac fibrosis at single-cell resolution shows CD248 in cardiac fibroblasts orchestrates interactions with immune cells

Post-injury remodeling is a complex process involving temporal specific cellular interactions in the injured tissue where the resident fibroblasts play multiple roles. Here, we performed single-cell and spatial transcriptome analysis in human and mouse infarcted hearts to dissect the molecular basis of these interactions. We identified a unique fibroblast subset with high CD248 expression, strongly associated with extracellular matrix remodeling. Genetic Cd248 deletion in fibroblasts mitigated cardiac fibrosis and dysfunction following ischemia/reperfusion. Mechanistically, CD248 stabilizes type I transforming growth factor beta receptor and thus upregulates fibroblast ACKR3 expression, leading to enhanced T cell retention. This CD248-mediated fibroblast-T cell interaction is required to sustain fibroblast activation and scar expansion. Disrupting this interaction using monoclonal antibody or chimeric antigen receptor T cell reduces T cell infiltration and consequently ameliorates cardiac fibrosis and dysfunction. Our findings reveal a CD248+ fibroblast subpopulation as a key regulator of immune-fibroblast cross-talk and a potential therapy to treat tissue fibrosis.

Stromal Stiffness-Regulated IGF2BP2 in Pancreatic Cancer Drives Immune Evasion via Sphingomyelin Metabolism

BACKGROUND AND AIMS

Immunotherapy has shown promising results in cancer treatment; however, it remains largely ineffective for pancreatic ductal adenocarcinoma (PDAC). N6-methyladenosine (m6A), known for its crucial role in cancer biology, is not yet fully understood regarding immune evasion. This study aims to elucidate the associations and mechanisms linking m6A modification with immune evasion in PDAC and propose strategies for clinical intervention.

METHODS

A multimodal PDAC cohort of 122 patients was developed, integrating transcriptomic profiling, imaging mass cytometry, and m6A quantification to identify m6A regulators associated with immunosuppressive tumor microenvironment (TME) and clinical outcomes. Findings were validated across 6 independent PDAC cohorts. Assays including MeRIP, RIP, and RNA pull-down confirmed that IGF2BP2 binds to targets, whereas scRNA-seq, flow cytometry, and mIHC profiled the TME. Preclinical interventions were tested in PDAC organoids, patient-derived tissue fragments, and humanized mouse models.

RESULTS

Our comprehensive analysis identified the m6A reader protein IGF2BP2 as a critical factor associated with poor prognosis in PDAC, linked to reduced effector cell infiltration and a fibrotic TME. High matrix stiffness in PDAC stabilized IGF2BP2, which subsequently promoted sphingomyelin synthesis via SGMS2 up-regulation. This pathway facilitates PD-L1 localization on membrane lipid rafts, enhancing immune evasion. The elastographic properties of PDAC enabled noninvasive screening of patients with overexpressed IGF2BP2/SGMS2. Disrupting sphingomyelin synthesis improved antitumor immunity and suppressed PDAC growth in humanized mice, highlighting immunotherapeutic opportunities for PDAC.

CONCLUSIONS

These findings emphasize the critical interplay between extrinsic matrix stiffness and intrinsic IGF2BP2-regulated sphingomyelin synthesis, identifying a promising target for immunotherapeutic strategies in PDAC.

Emodin Decreases Tumor-Associated Macrophages Accumulation and Suppresses Bladder Cancer Development by Inhibiting CXCL1 Secretion from Cancer-Associated Fibroblasts

Tumor-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs) are the most abundant stromal cells in the bladder cancer (BC) microenvironment (TME). However, the detailed mechanisms underlying TAM-CAF communication and their contributions to BC progression remain incompletely understood. Emerging evidence shows that Emodin exerts anti-tumor effect on several tumor models by targeting TME. To date, the impact of Emodin on BC has not been previously reported. Our study firstly demonstrated that Emodin significantly inhibited tumor growth and reduced TAM accumulation in a murine BC model. Emodin markedly decreased serum levels of multiple chemokines in tumor-bearing mice, with CXCL1 showing the most pronounced reduction. Strikingly, Emodin selectively suppressed CXCL1 secretion in CAFs but not in TAMs or tumor cells. Furthermore, the decrease in TAM migration induced by Emodin was dependent on CAF-derived CXCL1. Using a subcutaneous tumor model, we found that Emodin failed to inhibit tumor growth when CXCL1-deficient CAFs were co-injected with tumor cells, underscoring the critical role of CXCL1 in this process. Bioinformatics analysis further revealed that elevated CXCL1 levels correlated negatively with invasive/metastatic potential and overall survival in BC patients. In conclusion, our findings establish that Emodin delays BC progression by disrupting CXCL1-mediated crosstalk between CAFs and TAMs.

The fibroinflammatory response in cancer

Fibroinflammation refers to the highly integrated fibrogenic and inflammatory responses mediated by the concerted function of fibroblasts and innate immune cells in response to tissue perturbation. This process underlies the desmoplastic remodelling of the tumour microenvironment and thus plays an important role in tumour initiation, growth and metastasis. More specifically, fibroinflammation alters the biochemical and biomechanical signalling in malignant cells to promote their proliferation and survival and further supports an immunosuppressive microenvironment by polarizing the immune status of tumours. Additionally, the presence of fibroinflammation is often associated with therapeutic resistance. As such, there is increasing interest in targeting this process to normalize the tumour microenvironment and thus enhance the treatment of solid tumours. Herein, we review advances made in unravelling the complexity of cancer-associated fibroinflammation that can inform the rational design of therapies targeting this.

PD-1 antibody camrelizumab plus apatinib and SOX as first-line treatment in patients with AFP-producing gastric or gastro-esophageal junction adenocarcinoma (CAP 06): a multi-center, single-arm, phase 2 trial

Alpha-fetoprotein-producing gastric or gastro-esophageal junction (AFP-G/GEJ) cancer, a rare gastric cancer subtype, exhibits increased angiogenesis and more immunosuppression than non-AFP-G/GEJ cancer. The potential benefits of anti-angiogenic agents and immunotherapy for this specific subtype remain unknown. This multi-center, single-arm, phase 2 trial (ClinicalTrials.gov NCT04609176) evaluated the antitumor activity, safety, and biomarkers of camrelizumab plus apatinib and S-1 and oxaliplatin (SOX), followed by maintenance treatment with camrelizumab plus apatinib, as a first-line treatment in patients with AFP-G/GEJ adenocarcinoma. Primary endpoint was the confirmed objective response rate (ORR) per RECIST v1.1 in the full analysis set. Secondary endpoints were disease control rate (DCR), progression-free survival (PFS), overall survival (OS), duration of response, time to response, and safety. Between December 4, 2020, and August 4, 2023, 36 patients were enrolled and treated. The trial met its primary endpoint with a confirmed ORR of 66.7% (95% CI: 49.0-81.4). The DCR was 88.9% (95% CI: 73.9-96.9). With a median follow-up of 11.7 months (range: 3.2-37.9), the median PFS reached 7.8 months (95% CI: 4.9-12.3) and the median OS reached 18.0 months (95% CI: 10.5-NR). No new safety concerns were identified. In exploratory analysis, patients with durable clinical benefit exhibited higher pre-treatment (PD-1+) CD8+ T cell densities and effective scores. First-line treatment with camrelizumab plus apatinib and SOX, followed by maintenance treatment with camrelizumab plus apatinib, is effective and safe in AFP-G/GEJ adenocarcinoma. Further studies are necessary to validate these findings.

The impact of POSTN on tumor cell behavior and the tumor microenvironment in lung adenocarcinoma

BACKGROUND

The role of cancer-associated fibroblasts (CAFs) in modulating the anti-tumor immune response in lung adenocarcinoma (LUAD) remains elusive, primarily due to the heterogeneous nature of these cells. This heterogeneity muddles the understanding of their impact on immunotherapy effectiveness.

METHODS

We utilized the LUAD single-cell dataset to precisely classify tumor cells and CAFs. By employing CSOmap, we predicted cell interactions and reconstructed the three-dimensional spatial organization, highlighting the close association of myofibroblasts with specific tumor cell subsets. A prognostic signature based on myofibroblast-specific genes was developed and validated to predict LUAD patient survival. In vivo, we conducted subcutaneous tumorigenesis assays in mice, treating with PD-L1 and the POSTN inhibitor RGD to assess the combined effects of POSTN pathway blockade and immunotherapy on tumor growth and immune cell dynamics. For analyzing the tumor microenvironment, we used flow cytometry and multiplex immunofluorescence staining. In vitro, with cell lines like A549, H1299, and RAW264.7, we investigated POSTN's role in macrophage recruitment and polarization. Through ELISA, Western blot, and immunofluorescence staining, we explored how POSTN acts via ITGB3, providing a more comprehensive understanding of its mechanism in LUAD.

RESULTS

Our analysis discerned six distinct tumor cell subsets, with cluster 1 displaying pronounced cellular communication with myofibroblasts, evidenced by spatial accessibility in three dimensions. The myofibroblast-specific genomic signature was established and confirmed as a robust, independent prognostic indicator. Among the signature genes, CTHRC1, POSTN, and MMP11 emerged as high-variant genes in myofibroblasts, identified via the FindAllMarkers function in Seurat. Of these, only POSTN's differential expression correlated with LUAD prognosis, with high POSTN expression being indicative of poor patient outcomes. In vitro, recombinant POSTN was observed to enhance tumor invasiveness, motility, and proliferation, while attenuating apoptosis and fostering an EMT phenotype. Additionally, Transwell assays showed that rPOSTN could induce macrophage infiltration via ITGB3 and drive M2 polarization via the PI3K-Akt-JNK pathway. Importantly, blocking the POSTN pathway augmented the efficacy of PD-L1 inhibitors. In vivo, in a mouse subcutaneous tumorigenesis model, the combination of POSTN pathway blockade with PD-L1 inhibitor treatment notably inhibited tumor growth and changed the tumor microenvironment's immune cell composition, with an increase in CD8+ T cells and a favorable shift in the M1/M2 macrophage ratio.

CONCLUSION

This study sheds light on the intricate interplay between tumor cells and myofibroblasts in LUAD, pinpointing the pivotal role of the highly mutated gene POSTN. It underscores POSTN's instrumental role in manipulating the tumor microenvironment, primarily by promoting EMT and inhibiting apoptosis in lung cancer cells, alongside enhancing macrophage recruitment and fostering M2 polarization. These insights provide a foundation for enriching immunotherapy strategies, particularly through the inhibition of the POSTN pathway in LUAD.

Ligustilide Inhibits the PI3K/AKT Signalling Pathway and Suppresses Cholangiocarcinoma Cell Proliferation, Migration, and Invasion

BACKGROUND

Angelica sinensis (Oliv.) Diels, a renowned traditional Chinese medicine, has gained widespread recognition for its antitumor properties. Further investigation is warranted to determine whether ligustilide (LIG), which is extracted from this plant, can effectively inhibit tumors.

OBJECTIVES

We delved into the impact of LIG on cholangiocarcinoma cells, aiming to unravel the mechanisms underlying its effects.

MATERIALS AND METHODS

Cholangiocarcinoma cells (HuccT1 and RBE) were exposed to varying concentrations of LIG (2, 5, 10, 15, 20 μg/mL) for 24, 48, and 72 h. After identifying differentially expressed genes, stable transcription strains were utilized to explore LIG's antitumor mechanism. The inhibitory effects of LIG (5 μg/mL, 48 h) were assessed by CCK-8, colony formation, wound healing, transwell migration, western blotting, and immunofluorescence. In vivo, experiments in NOG mice (Ac, Ac+LIG; five per group) evaluated LIG's antiproliferative efficacy (5 mg/kg, intraperitoneal injection, 18-day period).

RESULTS

LIG significantly inhibited cell proliferation and migration with IC50 5.08 and 5.77 μg/mL in HuccT1 and RBE cell lines at 48h, increased the expression of E-cadherin while decreased N-cadherin and the protein of PI3K/AKT pathway. Silenced NDRG1 (N-Myc downstream- regulated gene 1) attenuated these effects. In vivo, the AC+LIG group (LIG, 5 mg/kg, qd, 18 d) exhibited smaller tumor volumes compared to the Ac group. The expression of Ki-67 was significantly downregulated in the AC+LIG group.

CONCLUSION

For the first time, our study has revealed that LIG holds therapeutic potential for treating cholangiocarcinoma. These findings hold promise for advancing innovative therapeutic approaches in the treatment of cholangiocarcinoma. LIG may serve as a useful patent for treating CCA.

Transcriptomic profiling of lung fibroblasts in silicosis: Regulatory roles of Nrf2 agonists in a mouse model

Silicosis is an occupational disease caused by long-term inhalation of free silica, resulting in a significant global health burden. Its pathogenesis remains unclear, and there is no effective treatment. Proliferative and activated myofibroblasts play a key role in the development of silicosis. Traditional studies have focused on fibroblast proliferation and collagen secretion, neglecting their functional heterogeneity. With the advancement of omics research, more pathogenic fibroblast subgroups and their functions have been identified. In this study, we applied transcriptomics to analyze gene changes in primary lung fibroblasts during silicosis development using a mouse model. Our results indicate that DEGs are enriched in collagen secretion, ECM synthesis, leukocyte migration, and chemotaxis functions. Altered core genes are associated with immune cell recruitment and cell migration. Nrf2 agonists, known for anti-inflammatory and antioxidant properties, have shown potential therapeutic effects in fibrotic diseases. However, their effects on fibroblasts in silicosis are not fully understood. We used four common Nrf2 agonists to study gene expression changes in lung fibroblasts at the transcriptome level, combined with histopathological and biochemical methods, to investigate their effects on silicosis in mice. Results show that Nrf2 agonists can exert anti-silicosis fibrosis functions by downregulating genes like Fos and Egr1, involved in cell differentiation, proliferation, and inflammation. In conclusion, this study suggests that inflammation-related co-functions of fibroblasts may be a potential mechanism in silicosis pathogenesis. Targeting Nrf2 may be a promising strategy to alleviate oxidative stress and inflammation in silicosis.

Unveiling immune cell response disparities in human primary cancer-associated fibroblasts between two- and three-dimensional cultures

Cancer-associated fibroblasts (CAFs) play pivotal roles in solid tumor initiation, growth, and immune evasion. However, the optimal biomimetic modeling conditions remain elusive. In this study, we investigated the effects of 2D and 3D culturing conditions on human primary CAFs integrated into a modular tumor microenvironment (TME). Using single-nucleus RNA sequencing (snRNAseq) and Proteomics' Proximity Extension Assays, we characterized CAF transcriptomic profiles and cytokine levels. Remarkably, when cultured in 2D, CAFs exhibited a myofibroblast (myCAF) subtype, whereas in 3D tumor spheroid cultures, CAFs displayed a more inflammatory (iCAF) pathological state. By integrating single-cell gene expression data with functional interrogations of critical TME-related processes [natural killer (NK)-mediated tumor killing, monocyte migration, and macrophage differentiation], we were able to reconcile form with function. In 3D TME spheroid models, CAFs enhance cancer cell growth and immunologically shield cells from NK cell-mediated cytotoxicity, in striking contrast with their 2D TME counterparts. Notably, 3D CAF-secreted proteins manifest a more immunosuppressive profile by enhancing monocyte transendothelial migration and differentiation into M2-like tumor-associated macrophages (TAMs). Our findings reveal a more immunosuppressive and clinically relevant desmoplastic TME model that can be employed in industrial drug discovery campaigns to expand the cellular target range of chemotherapeutics.

Dynamic Evolution of Fibroblasts Revealed by Single-Cell RNA Sequencing of Human Pancreatic Cancer

SIGNIFICANCE

Pancreatic cancer remains a high unmet medical need. Understanding the interactions between stroma and cancer cells in this disease may unveil new opportunities for therapeutic intervention.

Research Progress of Fibroblasts in Human Diseases

Fibroblasts, which originate from embryonic mesenchymal cells, are the predominant cell type seen in loose connective tissue. As the main components of the internal environment that cells depend on for survival, fibroblasts play an essential role in tissue development, wound healing, and the maintenance of tissue homeostasis. Furthermore, fibroblasts are also involved in several pathological processes, such as fibrosis, cancers, and some inflammatory diseases. In this review, we analyze the latest research progress on fibroblasts, summarize the biological characteristics and physiological functions of fibroblasts, and delve into the role of fibroblasts in disease pathogenesis and explore treatment approaches for fibroblast-related diseases.

Overcoming immunosuppression in cancer: how ketogenic diets boost immune checkpoint blockade

Immune checkpoint blockade (ICB) is now part of the standard of care in the treatment of many forms of cancer, yet it lacks efficacy in some patients, necessitating adjunct therapies to support the anti-tumor immune response. Ketogenic diets (KDs), i.e., high-fat low-carbohydrate diets, have been shown to have antiproliferative and immunomodulatory effects in various preclinical cancer studies. Here, we review current knowledge of the complex interplay of KDs and the anti-tumor immune response in the context of ICB therapy, to update our understanding of diet-induced immunometabolic reprogramming in cancer. Preclinical cancer studies have revealed increased activation of and infiltration by tumor-fighting immune cells, especially CD8+ T cells, but also M1 macrophages and natural killer cells, in response to a KD regimen. In contrast, immune-suppressive cells such as regulatory CD4+ T lymphocytes, M2 macrophages, and myeloid-derived suppressor cells were reported to be decreased or largely unaffected in tumors of KD-fed mice. KDs also showed synergism with ICB therapy in several preclinical tumor studies. The observed effects are ascribed to the ability of KDs to improve immune cell infiltration and induce downregulation of immune-inhibitory processes, thus creating a more immunogenic tumor microenvironment. The studies reviewed herein show that altering the metabolic composition of the tumor microenvironment by a KD can boost the anti-tumor immune response and diminish even immunotherapy-resistant as well as immunologically "cold" tumors. However, the exact underlying mechanisms remain to be elucidated, requiring further studies before KDs can be successfully implemented as an adjunct tumor therapy to improve survival rates for cancer patients.

Targeting fibroblast activation protein with chimeric antigen receptor macrophages

Under the rapid advancement of chimeric antigen receptor T cell (CAR-T) technology, CAR-macrophages (CAR-Ms) are also being developed currently in the pre-clinical stage and have been shown to inhibit tumor growth in several mouse tumor models. Fibroblast activation protein (FAP) is a type II transmembrane serine protease, which is expressed in stromal fibroblasts of over 90 % of common human epithelial cancers and is upregulated in fibrotic diseases of the liver, lung and colon, etc. In this study, we firstly constructed FAP-CAR macrophages to target FAP+ cells through in vitro phagocytosis assays. In subsequent in vivo assays, we discovered that FAP-CAR-ΔZETA bone marrow-derived macrophages (BMDMs) rather than FAP-CAR BMDMs, exhibited a pronounced anti-tumor effect in mouse subcutaneous MC38 colon cancer model. In addition, FAP-CAR and FAP-CAR-ΔZETA BMDMs therapy could effectively improve CCl4-induced liver fibrosis in mice. Collectively, CAR-Ms targeting FAP demonstrated great therapeutic potential in cancer and liver fibrosis therapy.

Single-cell RNA sequencing elucidated the landscape of breast cancer brain metastases and identified ILF2 as a potential therapeutic target

Distant metastasis remains the primary cause of morbidity in patients with breast cancer. Hence, the development of more efficacious strategies and the exploration of potential targets for patients with metastatic breast cancer are urgently needed. The data of six patients with breast cancer brain metastases (BCBrM) from two centres were collected, and a comprehensive landscape of the entire tumour ecosystem was generated through the utilisation of single-cell RNA sequencing. We utilised the Monocle2 and CellChat algorithms to investigate the interrelationships among each subcluster. In addition, multiple signatures were collected to evaluate key components of the subclusters through multi-omics methodologies. Finally, we elucidated common expression programs of malignant cells, and experiments were conducted in vitro and in vivo to determine the functions of interleukin enhancer-binding factor 2 (ILF2), which is a key gene in the metastasis module, in BCBrM progression. We found that subclusters in each major cell type exhibited diverse characteristics. Besides, our study indicated that ILF2 was specifically associated with BCBrM, and experimental validations further demonstrated that ILF2 deficiency hindered BCBrM progression. Our study offers novel perspectives on the heterogeneity of BCBrM and suggests that ILF2 could serve as a promising biomarker or therapeutic target for BCBrM.

The metabolic crosstalk of cancer-associated fibroblasts and tumor cells: Recent advances and future perspectives

Tumor cells grow in a microenvironment with a lack of nutrients and oxygen. Cancer-associated fibroblasts (CAFs) as one major component of tumor microenvironment have strong ability to survive under stressful conditions through metabolic remodelling. Furthermore, CAFs are educated by tumor cells and help them adapt to the hostile microenvironment through their metabolic communication. By inducing catabolism, CAFs release nutrients into the microenvironment which are taken up by tumor cells to satisfy their metabolic requirements. Furthermore, CAFs can recycle toxic metabolic wastes produced by cancer cells into energetic substances, allowing cancer cells to undergo biosynthesis. Their metabolic crosstalk also enhances CAFs' pro-tumor phenotype and reshape the microenvironment facilitating tumor cells' metastasis and immune escape. In this review, we have analyzed the effect and mechanisms of metabolic crosstalk between tumor cells and CAFs. We also analyzed the future perspectives in this area from the points of CAFs heterogeneity, spatial metabonomics and patient-derived tumor organoids (PDOs). These information may deepen the knowledge of tumor metabolism regulated by CAFs and provide novel insights into the development of metabolism-based anti-cancer strategies.

The axis of tumor-associated macrophages, extracellular matrix proteins, and cancer-associated fibroblasts in oncogenesis

The extracellular matrix (ECM) is a complex, dynamic network of multiple macromolecules that serve as a crucial structural and physical scaffold for neighboring cells. In the tumor microenvironment (TME), ECM proteins play a significant role in mediating cellular communication between cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs). Revealing the ECM modification of the TME necessitates the intricate signaling cascades that transpire among diverse cell populations and ECM proteins. The advent of single-cell sequencing has enabled the identification and refinement of specific cellular subpopulations, which has substantially enhanced our comprehension of the intricate milieu and given us a high-resolution perspective on the diversity of ECM proteins. However, it is essential to integrate single-cell data and establish a coherent framework. In this regard, we present a comprehensive review of the relationships among ECM, TAMs, and CAFs. This encompasses insights into the ECM proteins released by TAMs and CAFs, signaling integration in the TAM-ECM-CAF axis, and the potential applications and limitations of targeted therapies for CAFs. This review serves as a reliable resource for focused therapeutic strategies while highlighting the crucial role of ECM proteins as intermediates in the TME.

CAF-induced physical constraints controlling T cell state and localization in solid tumours

Solid tumours comprise cancer cells that engage in continuous interactions with non-malignant cells and with acellular components, forming the tumour microenvironment (TME). The TME has crucial and diverse roles in tumour progression and metastasis, and substantial efforts have been dedicated into understanding the functions of different cell types within the TME. These efforts highlighted the importance of non-cell-autonomous signalling in cancer, mediating interactions between the cancer cells, the immune microenvironment and the non-immune stroma. Much of this non-cell-autonomous signalling is mediated through acellular components of the TME, known as the extracellular matrix (ECM), and controlled by the cells that secrete and remodel the ECM - the cancer-associated fibroblasts (CAFs). In this Review, we delve into the complex crosstalk among cancer cells, CAFs and immune cells, highlighting the effects of CAF-induced ECM remodelling on T cell functions and offering insights into the potential of targeting ECM components to improve cancer therapies.

Neogambogic acid enhances anti-PD-1 immunotherapy efficacy by attenuating suppressive function of MDSCs in pancreatic cancer

BACKGROUND

Anti-PD-1-based immunotherapy has limited benefits in patients with pancreatic cancer. Accumulating data indicate that natural products exert antitumor activity by remodeling the tumor immune microenvironment. It has been reported that neogambogic acid (NGA), an active natural monomer extracted from Garcinia, has anti-inflammatory and antitumor effects. Nevertheless, there are few systematic studies on the antitumor efficacy and immunomodulatory effects of NGA in pancreatic cancer.

METHODS

An orthotopic mouse model of pancreatic cancer was established and were treated with different doses of NGA. Tumor growth and ascites were observed. Flow cytometry and immunohistochemistry (IHC) were used to investigate the tumor immune microenvironment. CD11b+ MDSCs were infused back into mice with pancreatic cancer to observe tumor progression after NGA treatment. Bone marrow cells were induced to differentiate into MDSCs, and the effects of NGA on MDSCs were analyzed and the underlying mechanism was explored. The effects of NGA combined with an anti-PD-1 antibody on pancreatic cancer were further tested.

RESULTS

NGA significantly inhibited the tumor growth and improve ascites character in pancreatic cancer model mice. Flow cytometry and IHC analysis revealed that NGA decreased the MDSCs proportion and infiltration in the tumor microenvironment. Moreover, adoptive MDSCs largely attenuated the inhibitory effect of NGA on the progression of pancreatic cancer. In addition, we showed that NGA significantly promoted apoptosis and inhibited the differentiation, migration and immunosuppressive function of MDSCs and decreased level of STAT3 and p-STAT3. Furthermore, we demonstrated that NGA synergistically enhanced the efficacy of anti-PD-1 antibodies against pancreatic cancer.

CONCLUSION

NGA inhibited the progression of pancreatic cancer by inhibiting MDSCs in the tumor microenvironment, and enhanced the efficacy of anti-PD-1 therapy in the treatment of pancreatic cancer.

Metabolic and Immunological Implications of MME+CAF-Mediated Hypoxia Signaling in Pancreatic Cancer Progression: Therapeutic Insights and Translational Opportunities

Pancreatic cancer is a devastating malignancy with a high mortality rate, poor prognosis, and limited treatment options. The tumor microenvironment (TME) plays a crucial role in tumor progression and therapy resistance. Multiple subpopulations of cancer-associated fibroblasts (CAFs) within the TME can switch between different states, exhibiting both antitumorigenic and protumorigenic functions in pancreatic cancer. It seems that targeting fibroblast-related proteins and other stromal components is an appealing approach to combat pancreatic cancer. This study employed single-cell transcriptome sequencing to identify MME (Membrane Metalloendopeptidase)-expressing CAFs in pancreatic cancer. Systematic screening was conducted based on tumor differentiation, lymph node metastasis, and T-stage parameters to identify and confirm the existence of a subpopulation of fibroblasts termed MME+CAFs. Subsequent analyses included temporal studies, exploration of intercellular communication patterns focusing on the hypoxia signaling pathway, and investigation of MME+CAF functions in the pancreatic cancer microenvironment. The pathway enrichment analysis and clinical relevance revealed a strong association between high MME expression and glycolysis, hypoxia markers, and pro-cancer inflammatory pathways. The role of MME+CAFs was validated through in vivo and in vitro experiments, including high-throughput drug screening to evaluate potential targeted therapeutic strategies. Single-cell transcriptome sequencing revealed tumor-associated fibroblasts with high MME expression, termed MME+CAF, exhibiting a unique end-stage differentiation function in the TME. MME+CAF involvement in the hypoxia signaling pathway suggested the potential effects on pancreatic cancer progression through intercellular communication. High MME expression was associated with increased glycolysis, hypoxia markers (VEGF), and pro-cancer inflammatory pathways in pancreatic cancer patients, correlating with lower survival rates, advanced disease stage, and higher oncogene mutation rates. Animal experiments confirmed that elevated MME expression in CAFs increases tumor burden, promotes an immunosuppressive microenvironment, and enhances resistance to chemotherapy and immunotherapy. The developed MME+CAF inhibitor IOX2 (a specific prolyl hydroxylase-2 (PHD2) inhibitor), combined with AG (Paclitaxel + Gemcitabine) and anti-PD1 therapy, demonstrated promising antitumor effects, offering a translational strategy for targeting MME in CAFs of pancreatic cancer. The study findings highlighted the significant role of MME+CAF in pancreatic cancer progression by shaping the TME and influencing key pathways. Targeting MME presented a promising strategy to combat the disease, with potential implications for therapeutic interventions aimed at disrupting MME+CAF functions and enhancing the efficacy of pancreatic cancer treatments.

Identification of a circadian-based prognostic signature predicting cancer-associated fibroblasts infiltration and immunotherapy response in bladder cancer

Circadian rhythm disruption impacts the efficiency of both chemotherapy and immunotherapy, yet identifying the key factors involved remains challenging. Circadian rhythm disruption can trigger aberrant fibroblasts activation, suggesting potential roles of cancer-associated fibroblasts (CAFs) in addressing this issue. In this paper, TCGA-BLCA patients were classified into two subgroups based on the expression of core circadian rhythm genes (CCRGs). The CCRG-based subgroups showed distinct fibroblast-related signals, from which a risk model composed of five fibroblast-related genes was finally established with excellent survival prognostic value in both TCGA and GEO datasets. The risk model was positively associated with the infiltration of CAFs and can efficiently predict the immunotherapy response in BLCA. Besides, high-risk score was associated with reduced sensitivity to a majority of traditional chemotherapeutic drugs such as oxaliplatin and gemcitabine. Further, the correlation between CCRGs and the risk genes was analyzed. Among the five risk genes, FAM20C displayed the most extensive correlation with the CCRGs and exhibited the strongest connection with CAFs infiltration. Moreover, FAM20C independently served as a predictor for the response to immunotherapy in BLCA. In conclusion, this study has identified a circadian-based signature for evaluating CAFs infiltration and predicting the efficacy of chemotherapy and immunotherapy. The central gene FAM20C has emerged as a promising candidate which merits further investigations.

Beyond CAR-T: The rise of CAR-NK cell therapy in asthma immunotherapy

Asthma poses a major public health burden. While existing asthma drugs manage symptoms for many, some patients remain resistant. The lack of a cure, especially for severe asthma, compels exploration of novel therapies. Cancer immunotherapy successes with CAR-T cells suggest its potential for asthma treatment. Researchers are exploring various approaches for allergic diseases including membrane-bound IgE, IL-5, PD-L2, and CTLA-4 for asthma, and Dectin-1 for fungal asthma. NK cells offer several advantages over T cells for CAR-based immunotherapy. They offer key benefits: (1) HLA compatibility, meaning they can be used in a wider range of patients without the need for matching tissue types. (2) Minimal side effects (CRS and GVHD) due to their limited persistence and cytokine profile. (3) Scalability for "off-the-shelf" production from various sources. Several strategies have been introduced that highlight the superiority and challenges of CAR-NK cell therapy for asthma treatment including IL-10, IFN-γ, ADCC, perforin-granzyme, FASL, KIR, NCRs (NKP46), DAP, DNAM-1, TGF-β, TNF-α, CCL, NKG2A, TF, and EGFR. Furthermore, we advocate for incorporating AI for CAR design optimization and CRISPR-Cas9 gene editing technology for precise gene manipulation to generate highly effective CAR constructs. This review will delve into the evolution and production of CAR designs, explore pre-clinical and clinical studies of CAR-based therapies in asthma, analyze strategies to optimize CAR-NK cell function, conduct a comparative analysis of CAR-T and CAR-NK cell therapy with their respective challenges, and finally present established novel CAR designs with promising potential for asthma treatment.

Decoding the spatiotemporal heterogeneity of tumor-associated macrophages

Tumor-associated macrophages (TAMs) are pivotal in cancer progression, influencing tumor growth, angiogenesis, and immune evasion. This review explores the spatial and temporal heterogeneity of TAMs within the tumor microenvironment (TME), highlighting their diverse subtypes, origins, and functions. Advanced technologies such as single-cell sequencing and spatial multi-omics have elucidated the intricate interactions between TAMs and other TME components, revealing the mechanisms behind their recruitment, polarization, and distribution. Key findings demonstrate that TAMs support tumor vascularization, promote epithelial-mesenchymal transition (EMT), and modulate extracellular matrix (ECM) remodeling, etc., thereby enhancing tumor invasiveness and metastasis. Understanding these complex dynamics offers new therapeutic targets for disrupting TAM-mediated pathways and overcoming drug resistance. This review underscores the potential of targeting TAMs to develop innovative cancer therapies, emphasizing the need for further research into their spatial characteristics and functional roles within the TME.

Progression of m6A in the tumor microenvironment: hypoxia, immune and metabolic reprogramming

Recently, N6-methyladenosine (m6A) has aroused widespread discussion in the scientific community as a mode of RNA modification. m6A comprises writers, erasers, and readers, which regulates RNA production, nuclear export, and translation and is very important for human health. A large number of studies have found that the regulation of m6A is closely related to the occurrence and invasion of tumors, while the homeostasis and function of the tumor microenvironment (TME) determine the occurrence and development of tumors to some extent. TME is composed of a variety of immune cells (T cells, B cells, etc.) and nonimmune cells (tumor-associated mesenchymal stem cells (TA-MSCs), cancer-associated fibroblasts (CAFs), etc.). Current studies suggest that m6A is involved in regulating the function of various cells in the TME, thereby affecting tumor progression. In this manuscript, we present the composition of m6A and TME, the relationship between m6A methylation and characteristic changes in TME, the role of m6A methylation in TME, and potential therapeutic strategies to provide new perspectives for better treatment of tumors in clinical work.

Senescence Defines a Distinct Subset of Myofibroblasts That Orchestrates Immunosuppression in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) therapeutic resistance is largely attributed to a unique tumor microenvironment embedded with an abundance of cancer-associated fibroblasts (CAF). Distinct CAF populations were recently identified, but the phenotypic drivers and specific impact of CAF heterogeneity remain unclear. In this study, we identify a subpopulation of senescent myofibroblastic CAFs (SenCAF) in mouse and human PDAC. These SenCAFs are a phenotypically distinct subset of myofibroblastic CAFs that localize near tumor ducts and accumulate with PDAC progression. To assess the impact of endogenous SenCAFs in PDAC, we used an LSL-KRASG12D;p53flox;p48-CRE;INK-ATTAC (KPPC-IA) mouse model of spontaneous PDAC with inducible senescent cell depletion. Depletion of senescent stromal cells in genetic and pharmacologic PDAC models relieved immune suppression by macrophages, delayed tumor progression, and increased responsiveness to chemotherapy. Collectively, our findings demonstrate that SenCAFs promote PDAC progression and immune cell dysfunction. Significance: CAF heterogeneity in PDAC remains poorly understood. In this study, we identify a novel subpopulation of senescent CAFs that promotes PDAC progression and immunosuppression. Targeting CAF senescence in combination therapies could increase tumor vulnerability to chemo or immunotherapy. See related article by Ye et al., p. 1302.

Hydrogen Therapy Reverses Cancer-Associated Fibroblasts Phenotypes and Remodels Stromal Microenvironment to Stimulate Systematic Anti-Tumor Immunity

Tumor microenvironment (TME) plays an important role in the tumor progression. Among TME components, cancer-associated fibroblasts (CAFs) show multiple tumor-promoting effects and can induce tumor immune evasion and drug-resistance. Regulating CAFs can be a potential strategy to augment systemic anti-tumor immunity. Here, the study observes that hydrogen treatment can alleviate intracellular reactive oxygen species of CAFs and reshape CAFs' tumor-promoting and immune-suppressive phenotypes. Accordingly, a controllable and TME-responsive hydrogen therapy based on a CaCO3 nanoparticles-coated magnesium system (Mg-CaCO3) is developed. The hydrogen therapy by Mg-CaCO3 can not only directly kill tumor cells, but also inhibit pro-tumor and immune suppressive factors in CAFs, and thus augment immune activities of CD4+ T cells. As implanted in situ, Mg-CaCO3 can significantly suppress tumor growth, turn the "cold" primary tumor into "hot", and stimulate systematic anti-tumor immunity, which is confirmed by the bilateral tumor transplantation models of "cold tumor" (4T1 cells) and "hot tumor" (MC38 cells). This hydrogen therapy system reverses immune suppressive phenotypes of CAFs, thus providing a systematic anti-tumor immune stimulating strategy by remodeling tumor stromal microenvironment.

Recent advances in understanding the immune microenvironment in ovarian cancer

The occurrence of ovarian cancer (OC) is a major factor in women's mortality rates. Despite progress in medical treatments, like new drugs targeting homologous recombination deficiency, survival rates for OC patients are still not ideal. The tumor microenvironment (TME) includes cancer cells, fibroblasts linked to cancer (CAFs), immune-inflammatory cells, and the substances these cells secrete, along with non-cellular components in the extracellular matrix (ECM). First, the TME mainly plays a role in inhibiting tumor growth and protecting normal cell survival. As tumors progress, the TME gradually becomes a place to promote tumor cell progression. Immune cells in the TME have attracted much attention as targets for immunotherapy. Immune checkpoint inhibitor (ICI) therapy has the potential to regulate the TME, suppressing factors that facilitate tumor advancement, reactivating immune cells, managing tumor growth, and extending the survival of patients with advanced cancer. This review presents an outline of current studies on the distinct cellular elements within the OC TME, detailing their main functions and possible signaling pathways. Additionally, we examine immunotherapy rechallenge in OC, with a specific emphasis on the biological reasons behind resistance to ICIs.

Mapping the tumor stress network reveals dynamic shifts in the stromal oxidative stress response

The tumor microenvironment (TME) presents cells with challenges such as variable pH, hypoxia, and free radicals, triggering stress responses that affect cancer progression. In this study, we examine the stress response landscape in four carcinomas-breast, pancreas, ovary, and prostate-across five pathways: heat shock, oxidative stress, hypoxia, DNA damage, and unfolded protein stress. Using a combination of experimental and computational methods, we create an atlas of stress responses across various types of carcinomas. We find that stress responses vary within the TME and are especially active near cancer cells. Focusing on the non-immune stroma we find, across tumor types, that NRF2 and the oxidative stress response are distinctly activated in immune-regulatory cancer-associated fibroblasts and in a unique subset of cancer-associated pericytes. Our study thus provides an interactome of stress responses in cancer, offering ways to intersect survival pathways within the tumor, and advance cancer therapy.

Cancer-associated fibroblasts promote enzalutamide resistance and PD-L1 expression in prostate cancer through CCL5-CCR5 paracrine axis

Cancer-associated fibroblasts (CAFs) have been shown to play a key role in prostate cancer treatment resistance, but the role of CAFs in the initial course of enzalutamide therapy for prostate cancer remains unclear. Our research revealed that CAFs secrete CCL5, which promotes the upregulation of androgen receptor (AR) expression in prostate cancer cells, leading to resistance to enzalutamide therapy. Furthermore, CCL5 also enhances the expression of tumor programmed death-ligand 1 (PD-L1), resulting in immune escape. Mechanistically, CCL5 binds to the receptor CCR5 on prostate cancer cells and activates the AKT signaling pathway, leading to the upregulation of AR and PD-L1. The CCR5 antagonist maraviroc to inhibit the CAFs mediated CCL5 signaling pathway can effectively reduce the expression of AR and PD-L1, and improve the efficacy of enzalutamide. This study highlights a promising therapeutic approach targeting the CCL5-CCR5 signaling pathway to improve the effectiveness of enzalutamide.

CPT1C-positive cancer-associated fibroblast facilitates immunosuppression through promoting IL-6-induced M2-like phenotype of macrophage

Cancer-associated fibroblasts (CAFs) exhibit remarkable phenotypic heterogeneity, with specific subsets implicated in immunosuppression in various malignancies. However, whether and how they attenuate anti-tumor immunity in gastric cancer (GC) remains elusive. CPT1C, a unique isoform of carnitine palmitoyltransferase pivotal in regulating fatty acid oxidation, is briefly indicated as a protumoral metabolic mediator in the tumor microenvironment (TME) of GC. In the present study, we initially identified specific subsets of fibroblasts exclusively overexpressing CPT1C, hereby termed them as CPT1C+CAFs. Subsequent findings indicated that CPT1C+CAFs fostered a stroma-enriched and immunosuppressive TME as they correlated with extracellular matrix-related molecular features and enrichment of both immunosuppressive subsets, especially M2-like macrophages, and multiple immune-related pathways. Next, we identified that CPT1C+CAFs promoted the M2-like phenotype of macrophage in vitro. Bioinformatic analyses unveiled the robust IL-6 signaling between CPT1C+CAFs and M2-like phenotype of macrophage and identified CPT1C+CAFs as the primary source of IL-6. Meanwhile, suppressing CPT1C expression in CAFs significantly decreased IL-6 secretion in vitro. Lastly, we demonstrated the association of CPT1C+CAFs with therapeutic resistance. Notably, GC patients with high CPT1C+CAFs infiltration responded poorly to immunotherapy in clinical cohort. Collectively, our data not only present the novel identification of CPT1C+CAFs as immunosuppressive subsets in TME of GC, but also reveal the underlying mechanism that CPT1C+CAFs impair tumor immunity by secreting IL-6 to induce the immunosuppressive M2-like phenotype of macrophage in GC.

Extracellular matrix stiffness and tumor-associated macrophage polarization: new fields affecting immune exclusion

In the malignant progression of tumors, there is deposition and cross-linking of collagen, as well as an increase in hyaluronic acid content, which can lead to an increase in extracellular matrix stiffness. Recent research evidence have shown that the extracellular matrix plays an important role in angiogenesis, cell proliferation, migration, immunosuppression, apoptosis, metabolism, and resistance to chemotherapeutic by the alterations toward both secretion and degradation. The clinical importance of tumor-associated macrophage is increasingly recognized, and macrophage polarization plays a central role in a series of tumor immune processes through internal signal cascade, thus regulating tumor progression. Immunotherapy has gradually become a reliable potential treatment strategy for conventional chemotherapy resistance and advanced cancer patients, but the presence of immune exclusion has become a major obstacle to treatment effectiveness, and the reasons for their resistance to these approaches remain uncertain. Currently, there is a lack of exact mechanism on the regulation of extracellular matrix stiffness and tumor-associated macrophage polarization on immune exclusion. An in-depth understanding of the relationship between extracellular matrix stiffness, tumor-associated macrophage polarization, and immune exclusion will help reveal new therapeutic targets and guide the development of clinical treatment methods for advanced cancer patients. This review summarized the different pathways and potential molecular mechanisms of extracellular matrix stiffness and tumor-associated macrophage polarization involved in immune exclusion and provided available strategies to address immune exclusion.

Single-cell and multi-omics analyses highlight cancer-associated fibroblasts-induced immune evasion and epithelial mesenchymal transition for smoking bladder cancer

Tobacco carcinogens are recognized as critical hazard factors for bladder tumorigenesis, affecting the prognosis of patients through aromatic amines components. However, the specific function of tobacco carcinogens and systematic assessment models in the prognosis of bladder cancer remains poorly elucidated. We retrieved bladder cancer specific tobacco carcinogens-related genes from Comparative Toxicogenomic Database, our Nanjing Bladder Cancer cohort and TCGA database. Gene×Gene interaction method was utilized to establish a prognostic signature. Integrative assessment of immunogenomics, tumor microenvironments and single-cell RNA-sequencing were performed to illustrate the internal relations of key events from different levels. Finally, we comprehensively identified 33 essential tobacco carcinogens-related genes to construct a novel prognostic signature, and found that high-risk patients were characterized by significantly worse overall survival (HR=2.25; Plog-rank < 0.01). Single-cell RNA-sequencing and multi-omics analysis demonstrated that cancer-associated fibroblasts mediated the crosstalk between epithelial-mesenchymal transition progression and immune evasion. Moreover, an adverse outcome pathway framework was established to facilitate our understanding to the tobacco carcinogens-triggered bladder tumorigenesis. Our study systematically provided immune microenvironmental alternations for smoking-induced adverse survival outcomes in bladder cancer. These findings facilitated the integrative multi-omics insights into risk assessment and toxic mechanisms of tobacco carcinogens.

Anti-stromal nanotherapeutics for hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the most commonly diagnosed primary liver cancer, has become a leading cause of cancer-related death worldwide. Accumulating evidence confirms that the stromal constituents within the tumor microenvironment (TME) exacerbate HCC malignancy and set the barriers to current anti-HCC treatments. Recent developments of nano drug delivery system (NDDS) have facilitated the application of stroma-targeting therapeutics, disrupting the stromal TME in HCC. This review discusses the stromal activities in HCC development and therapy resistance. In addition, it addresses the delivery challenges of NDDS for stroma-targeting therapeutics (termed anti-stromal nanotherapeutics in this review), and provides recent advances in anti-stromal nanotherapeutics for safe, effective, and specific HCC therapy.

Intercellular crosstalk between cancer cells and cancer-associated fibroblasts via exosomes in gastrointestinal tumors

Gastrointestinal (GI) tumors are a significant global health threat, with high rates of morbidity and mortality. Exosomes contain various biologically active molecules like nucleic acids, proteins, and lipids and can serve as messengers for intercellular communication. They play critical roles in the exchange of information between tumor cells and the tumor microenvironment (TME). The TME consists of mesenchymal cells and components of the extracellular matrix (ECM), with fibroblasts being the most abundant cell type in the tumor mesenchyme. Cancer-associated fibroblasts (CAFs) are derived from normal fibroblasts and mesenchymal stem cells that are activated in the TME. CAFs can secrete exosomes to modulate cell proliferation, invasion, migration, drug resistance, and other biological processes in tumors. Additionally, tumor cells can manipulate the function and behavior of fibroblasts through direct cell-cell interactions. This review provides a summary of the intercellular crosstalk between GI tumor cells and CAFs through exosomes, along with potential underlying mechanisms.

Pan-cancer analysis of the tumorigenic role of Fanconi anemia complementation group D2 (FANCD2) in human tumors

Monoubiquitination of FANCD2 is a central step in the activation of the Fanconi anemia (FA) pathway after DNA damage. Defects in the FA pathway centered around FANCD2 not only lead to genomic instability but also induce tumorigenesis. At present, few studies have investigated FANCD2 in tumors, and no pan-cancer research on FANCD2 has been conducted. We conducted a comprehensive analysis of the role of FANCD2 in cancer using public databases and other published studies. Moreover, we evaluated the role of FANCD2 in the proliferation, migration and invasion of lung adenocarcinoma cells through in vitro and in vivo experiments, and explored the role of FANCD2 in cisplatin chemoresistance. We investigated the regulatory effect of FANCD2 on the cell cycle of lung adenocarcinoma cells by flow cytometry, and verified this effect by western blotting. FANCD2 expression is elevated in most TCGA tumors and shows a strong positive correlation with poor prognosis in tumor patients. In addition, FANCD2 expression shows strong correlations with immune infiltration, immune checkpoints, the tumor mutation burden (TMB), and microsatellite instability (MSI), which are immune-related features, suggesting that it may be a potential target of tumor immunotherapy. We further found that FANCD2 significantly promotes the proliferation, invasion, and migration abilities of lung adenocarcinoma cells and that its ability to promote cancer cell proliferation may be achieved by modulating the cell cycle. The findings indicate that FANCD2 is a potential biomarker and therapeutic target in cancer treatment by analyzing the oncogenic role of FANCD2 in different tumors.

NETosis: Sculpting tumor metastasis and immunotherapy

The process of neutrophil extracellular traps (NETs) formation, called NETosis, is a peculiar death modality of neutrophils, which was first observed as an immune response against bacterial infection. However, recent work has revealed the unique biology of NETosis in facilitating tumor metastatic process. Neutrophil extracellular traps released by the tumor microenvironment (TME) shield tumor cells from cytotoxic immunity, leading to impaired tumor clearance. Besides, tumor cells tapped by NETs enable to travel through vessels and subsequently seed distant organs. Targeted ablation of NETosis has been proven to be beneficial in potentiating the efficacy of cancer immunotherapy in the metastatic settings. This review outlines the impact of NETosis at almost all stages of tumor metastasis. Furthermore, understanding the multifaceted interplay between NETosis and the TME components is crucial for supporting the rational development of highly effective combination immunotherapeutic strategies with anti-NETosis for patients with metastatic disease.

Transcription factors in fibroblast plasticity and CAF heterogeneity

In recent years, research focused on the multifaceted landscape and functions of cancer-associated fibroblasts (CAFs) aimed to reveal their heterogeneity and identify commonalities across diverse tumors for more effective therapeutic targeting of pro-tumoral stromal microenvironment. However, a unified functional categorization of CAF subsets remains elusive, posing challenges for the development of targeted CAF therapies in clinical settings.The CAF phenotype arises from a complex interplay of signals within the tumor microenvironment, where transcription factors serve as central mediators of various cellular pathways. Recent advances in single-cell RNA sequencing technology have emphasized the role of transcription factors in the conversion of normal fibroblasts to distinct CAF subtypes across various cancer types.This review provides a comprehensive overview of the specific roles of transcription factor networks in shaping CAF heterogeneity, plasticity, and functionality. Beginning with their influence on fibroblast homeostasis and reprogramming during wound healing and fibrosis, it delves into the emerging insights into transcription factor regulatory networks. Understanding these mechanisms not only enables a more precise characterization of CAF subsets but also sheds light on the early regulatory processes governing CAF heterogeneity and functionality. Ultimately, this knowledge may unveil novel therapeutic targets for cancer treatment, addressing the existing challenges of stromal-targeted therapies.

Forks in the road for CAR T and CAR NK cell cancer therapies

The advent of chimeric antigen receptor (CAR) T cell therapy has resulted in unprecedented long-term clearance of relapse/refractory hematological malignancies in both pediatric and adult patients. However, severe toxicities, such as cytokine release syndrome and neurotoxicity, associated with CAR T cells affect therapeutic utility; and treatment efficacies for solid tumors are still not impressive. As a result, engineering strategies that modify other immune cell types, especially natural killer (NK) cells have arisen. Owing to both CAR-dependent and CAR-independent (innate immune-mediated) antitumor killing capacity, major histocompatibility complex-independent cytotoxicity, reduced risk of alloreactivity and lack of major CAR T cell toxicities, CAR NK cells constitute one of the promising next-generation CAR immune cells that are also amenable as 'off-the-shelf' therapeutics. In this Review, we compare CAR T and CAR NK cell therapies, with particular focus on immunological synapses, engineering strategies and challenges.

Single-cell and spatial transcriptomics reveal POSTN+ cancer-associated fibroblasts correlated with immune suppression and tumour progression in non-small cell lung cancer

BACKGROUND

Cancer-associated fibroblasts (CAFs) are potential targets for cancer therapy. Due to the heterogeneity of CAFs, the influence of CAF subpopulations on the progression of lung cancer is still unclear, which impedes the translational advances in targeting CAFs.

METHODS

We performed single-cell RNA sequencing (scRNA-seq) on tumour, paired tumour-adjacent, and normal samples from 16 non-small cell lung cancer (NSCLC) patients. CAF subpopulations were analyzed after integration with published NSCLC scRNA-seq data. SpaTial enhanced resolution omics-sequencing (Stereo-seq) was applied in tumour and tumour-adjacent samples from seven NSCLC patients to map the architecture of major cell populations in tumour microenvironment (TME). Immunohistochemistry (IHC) and multiplexed IHC (mIHC) were used to validate marker gene expression and the association of CAFs with immune infiltration in TME.

RESULTS

A subcluster of myofibroblastic CAFs, POSTN+ CAFs, were significantly enriched in advanced tumours and presented gene expression signatures related to extracellular matrix remodeling, tumour invasion pathways and immune suppression. Stereo-seq and mIHC demonstrated that POSTN+ CAFs were in close localization with SPP1+ macrophages and were associated with the exhausted phenotype and lower infiltration of T cells. POSTN expression or the abundance of POSTN+ CAFs were associated with poor prognosis of NSCLC.

CONCLUSIONS

Our study identified a myofibroblastic CAF subpopulation, POSTN+ CAFs, which might associate with SPP1+ macrophages to promote the formation of desmoplastic architecture and participate in immune suppression. Furthermore, we showed that POSTN+ CAFs associated with cancer progression and poor clinical outcomes and may provide new insights on the treatment of NSCLC.

Microenvironmental regulation in tumor progression: Interactions between cancer-associated fibroblasts and immune cells

The tumor microenvironment (TME), the "soil" on which tumor cells grow, has an important role in regulating the proliferation and metastasis of tumor cells as well as their response to treatment. Cancer-associated fibroblasts (CAFs), as the most abundant stromal cells of the TME, can not only directly alter the immunosuppressive effect of the TME through their own metabolism, but also influence the aggregation and function of immune cells by secreting a large number of cytokines and chemokines, reducing the body's immune surveillance of tumor cells and making them more prone to immune escape. Our study provides a comprehensive review of fibroblast chemotaxis, malignant transformation, metabolic characteristics, and interactions with immune cells. In addition, the current small molecule drugs targeting CAFs have been summarized, including both natural small molecules and targeted drugs for current clinical therapeutic applications. A complete review of the role of fibroblasts in TME from an immune perspective is presented, which has important implications in improving the efficiency of immunotherapy by targeting fibroblasts.

The tumor microenvironment shows a hierarchy of cell-cell interactions dominated by fibroblasts

The tumor microenvironment (TME) is comprised of non-malignant cells that interact with each other and with cancer cells, critically impacting cancer biology. The TME is complex, and understanding it requires simplifying approaches. Here we provide an experimental-mathematical approach to decompose the TME into small circuits of interacting cell types. We find, using female breast cancer single-cell-RNA-sequencing data, a hierarchical network of interactions, with cancer-associated fibroblasts (CAFs) at the top secreting factors primarily to tumor-associated macrophages (TAMs). This network is composed of repeating circuit motifs. We isolate the strongest two-cell circuit motif by culturing fibroblasts and macrophages in-vitro, and analyze their dynamics and transcriptomes. This isolated circuit recapitulates the hierarchy of in-vivo interactions, and enables testing the effect of ligand-receptor interactions on cell dynamics and function, as we demonstrate by identifying a mediator of CAF-TAM interactions - RARRES2, and its receptor CMKLR1. Thus, the complexity of the TME may be simplified by identifying small circuits, facilitating the development of strategies to modulate the TME.

Ruth Scherz-Shouval: Together we can ask big questions

Ruth Scherz-Shouval is an Assistant Professor in the Department of Biomolecular Sciences at the Weizmann Institute of Science, Israel. Her lab is interested in the tumor microenvironment, how stress responses can shape the tumor microenvironment, and also how different cells within the tumor microenvironment interact. We talked about how her interest in science began at an early age, the impact of having strong female role models, and ways to encourage collaboration and create an engaging and welcoming lab environment.