Redefining macrophage and neutrophil biology in the metastatic cascade

Cellular senescence and metabolic reprogramming: Unraveling the intricate crosstalk in the immunosuppressive tumor microenvironment

The intrinsic oncogenic mechanisms and properties of the tumor microenvironment (TME) have been extensively investigated. Primary features of the TME include metabolic reprogramming, hypoxia, chronic inflammation, and tumor immunosuppression. Previous studies suggest that senescence-associated secretory phenotypes that mediate intercellular information exchange play a role in the dynamic evolution of the TME. Specifically, hypoxic adaptation, metabolic dysregulation, and phenotypic shifts in immune cells regulated by cellular senescence synergistically contribute to the development of an immunosuppressive microenvironment and chronic inflammation, thereby promoting the progression of tumor events. This review provides a comprehensive summary of the processes by which cellular senescence regulates the dynamic evolution of the tumor-adapted TME, with focus on the complex mechanisms underlying the relationship between senescence and changes in the biological functions of tumor cells. The available findings suggest that components of the TME collectively contribute to the progression of tumor events. The potential applications and challenges of targeted cellular senescence-based and combination therapies in clinical settings are further discussed within the context of advancing cellular senescence-related research.

The Past and Future of Angiogenesis as a Target for Cancer Therapy and Prevention

Cancer growth is dependent on angiogenesis, the formation of new blood vessels, which represents a hallmark of cancer. After this concept was established in the 1970s, inhibition of tumor development and metastases by blocking the neoangiogenic process has been an important approach to the treatment of tumors. However, antiangiogenic therapies are often administered when cancer has already progressed. The key to reducing the cancer burden is prevention. We noticed 20 years ago that a series of possible cancer chemopreventive agents showed antiangiogenic properties when tested in experimental models. This article reviews the relevant advances in the understanding of the rationale for targeting angiogenesis for cancer therapy, prevention, and interception and recently investigated substances with antiangiogenic activity that may be suitable for such strategies. Many compounds, either dietary derivatives or repurposed drugs, with antiangiogenic activity are possible tools for cancer angioprevention. Such molecules have a favorable safety profile and are likely to allow the prolonged duration necessary for an efficient preventive strategy. Recent evidence on mechanisms and possible use is described here for food derivatives, including flavonoids, retinoids, triterpenoids, omega fatty acids, and carotenoids from marine microorganisms. As examples, a number of compounds, including epigallocatechin, resveratrol, xanthohumol, hydroxytyrosol, curcumin, fenretinide, lycopene, fucoxanthin, and repurposed drugs, such as aspirin, β blockers, renin-angiotensin-aldosterone inhibitors, carnitines, and biguanides, are reviewed.

Tumor cell-derived exosomal miR-193b-3p promotes tumor-associated macrophage activation to facilitate nasopharyngeal cancer cell invasion and radioresistances

Background

Communication between cancer cells and tumor-associated macrophages (TAMs) in the tumor microenvironment (TME) plays a crucial role in accelerating nasopharyngeal cancer (NPC) metastasis and radioresistance. However, the mechanisms through which NPC cells regulate the properties and activation of TAMs during NPC progression are not yet fully understood.

Methods

A high-metastatic NPC subclone (HMC) and a low-metastatic NPC subclone (LMC) were screened from the CNE-2 cell line and exosomes were collected from HMCs and LMCs, respectively. The effects of HMC- and LMC-derived exosomes (HMC-Exos and LMC-Exos) on the regulation of TAM activation were evaluated by assessing the levels of inflammation-related or immunosuppression-related genes. The role of miRNA-193b-3p (miR-193b) in mediating communication between NPCs and TAMs was assessed using real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR), Western blot analysis, Transwell assays, and clonogenic survival assays.

Results

HMCs and HMC-Exos exhibited a greater capacity to facilitate macrophage protumorigenic activation than LMCs and LMC-Exos. miR-193b levels derived from HMC-Exos were higher than those from LMC-Exos, and miR-193b levels were higher in metastatic NPC tissue-derived TAMs than in non-metastatic NPC tissue-derived TAMs. The upregulated miR-193b was packaged into exosomes and transferred to macrophages. Functionally, miR-193b up-regulation accelerated TAM activation by directly targeting mitogen-activated protein/ERK kinase kinase 3 (MEKK3). As a result, miR-193b-overexpressed macrophages facilitated NPC cell invasion and radioresistance.

Conclusions

These data revealed a critical role for exosomal miR-193b in mediating intercellular communication between NPC cells and macrophages, providing a potential target for NPC treatment.

Emerging Trends in Gastrointestinal Cancer Targeted Therapies: Harnessing Tumor Microenvironment, Immune Factors, and Metabolomics Insights

Gastrointestinal (GI) cancers are the leading cause of new cancer cases and cancer-related deaths worldwide. The treatment strategies for patients with GI tumors have focused on oncogenic molecular profiles associated with tumor cells. Recent evidence has demonstrated that the tumor cell functions are modulated by its microenvironment, compromising fibroblasts, extracellular matrices, microbiome, immune cells, and the enteric nervous system. Along with the tumor microenvironment components, alterations in key metabolic pathways have emerged as a hallmark of tumor cells. From these perspectives, this review will highlight the functions of different cellular components of the GI tumor microenvironment and their implications for treatment. Furthermore, we discuss the major metabolic reprogramming in GI tumor cells and how understanding metabolic rewiring could lead to new therapeutic strategies. Finally, we briefly summarize the targeted agents currently being studied in GI cancers. Understanding the complex interplay between tumor cell-intrinsic and -extrinsic factors during tumor progression is critical for developing new therapeutic strategies.

Traditional Chinese Medicine in Regulating Tumor Microenvironment

Tumor microenvironment (TME) is a complex and integrated system containing a variety of tumor-infiltrating immune cells and stromal cells. They are closely connected with cancer cells and influence the development and progression of cancer. Traditional Chinese medicine (TCM) is an important complementary therapy for cancer treatment in China. It mainly eliminates cancer cells by regulating TME. The aim of this review is to systematically summarize the crosstalk between tumor cells and TME, and to summarize the research progress of TCM in regulating TME. The review is of great significance in revealing the therapeutic mechanism of action of TCM, and provides an opportunity for the combined application of TCM and immunotherapy in cancer treatment.

Forces at play: exploring factors affecting the cancer metastasis

Metastatic disease, a leading and lethal indication of deaths associated with tumors, results from the dissemination of metastatic tumor cells from the site of primary origin to a distant organ. Dispersion of metastatic cells during the development of tumors at distant organs leads to failure to comply with conventional treatments, ultimately instigating abrupt tissue homeostasis and organ failure. Increasing evidence indicates that the tumor microenvironment (TME) is a crucial factor in cancer progression and the process of metastatic tumor development at secondary sites. TME comprises several factors contributing to the initiation and progression of the metastatic cascade. Among these, various cell types in TME, such as mesenchymal stem cells (MSCs), lymphatic endothelial cells (LECs), cancer-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), T cells, and tumor-associated macrophages (TAMs), are significant players participating in cancer metastasis. Besides, various other factors, such as extracellular matrix (ECM), gut microbiota, circadian rhythm, and hypoxia, also shape the TME and impact the metastatic cascade. A thorough understanding of the functions of TME components in tumor progression and metastasis is necessary to discover new therapeutic strategies targeting the metastatic tumor cells and TME. Therefore, we reviewed these pivotal TME components and highlighted the background knowledge on how these cell types and disrupted components of TME influence the metastatic cascade and establish the premetastatic niche. This review will help researchers identify these altered components' molecular patterns and design an optimized, targeted therapy to treat solid tumors and restrict metastatic cascade.

Current state of immune checkpoints therapy for glioblastoma

Glioblastoma (GBM), one of the most aggressive forms of brain cancer, has limited treatment options. Recent years have witnessed the remarkable success of checkpoint inhibitor immunotherapy across various cancer types. Against this backdrop, several clinical trials investigating checkpoint inhibitors for GBM are underway in multiple countries. Furthermore, the integration of immunotherapy with traditional treatment approaches is now emerging as a highly promising strategy. This review summarizes the latest advancements in checkpoint inhibitor immunotherapy for GBM treatment. We provide a concise yet comprehensive overview of current GBM immunotherapy options. Additionally, this review underscores combination strategies and potential biomarkers for predicting response and resistance in GBM immunotherapies.

3D Bioprinting: An Important Tool for Tumor Microenvironment Research

The tumor microenvironment plays a crucial role in cancer development and treatment. Traditional 2D cell cultures fail to fully replicate the complete tumor microenvironment, while mouse tumor models suffer from time-consuming procedures and complex operations. However, in recent years, 3D bioprinting technology has emerged as a vital tool in studying the tumor microenvironment. 3D bioprinting is a revolutionary biomanufacturing technique that involves layer-by-layer stacking of biological materials, such as cells and biomaterial scaffolds, to create highly precise 3D biostructures. This technology enables the construction of intricate tissue and organ models in the laboratory, which are utilized for biomedical research, drug development, and personalized medicine. The application of 3D bioprinting has brought unprecedented opportunities to fields such as cancer research, tissue engineering, and organ transplantation. It has opened new possibilities for addressing real-world biological challenges and improving medical treatment outcomes. This review summarizes the applications of 3D bioprinting technology in the context of the tumor microenvironment, aiming to explore its potential impact on cancer research and treatment. The use of this cutting-edge technology promises significant advancements in understanding cancer biology and enhancing medical interventions.

MUC16 stimulates neutrophils to an inflammatory and immunosuppressive phenotype in ovarian cancer

BACKGROUND

MUC16 (CA125) is a commonly used tumor marker for ovarian cancer screening and reported to be an immunosuppressive factor by acting on the sialic acid-binding immunoglobulin-like lectin-9 (Siglec-9) on the surface of natural killer cells (NK cells), B cells, and monocytes. However, the role of MUC16 on neutrophils in the tumor microenvironment remains to be further explored.

METHODS

The correlation between the proportion and count of peripheral blood cells, serum inflammatory-related factors and serum MUC16 (CA125) level in patients was constructed based on clinical samples. RNAseq data was obtained from TCGA and sequencing of ovarian cancer tissues, followed by TIMER immune cell infiltration and correlation analysis. Ovarian cancer organoid was constructed to stimulate neutrophils with immunophenotype identification by qPCR and flow cytometry. MUC16 protein stimulation to neutrophils validated the role of MUC16 under the analysis of RNA sequencing and inhibition of NK cytotoxicity in vitro.

RESULTS

The serum MUC16 level was positively correlated with the proportion and count of peripheral blood neutrophils, neutrophil-to-lymphocyte ratio (NLR) and inflammatory factors IL-6, IL-8, IL-10 and IL-2R. Siglec-9, the receptor of MUC16, was expressed on neutrophils and was positively correlated to neutrophil infiltration in ovarian cancer. After the stimulation of ovarian cancer organoids and MUC16 respectively, the proportions of CD11b+, CD66b+, and ICAM-1+ neutrophils were significantly increased, while the proportion of CXCR4+ neutrophils was slightly decreased, with increasing of of inflammatory factors MMP9, IL-8, OSM, IL-1β, TNF-α, CXCL3, and ROS. RNA-sequencing analysis revealed that inflammatory response, TNFA signaling pathway, and IL6-related pathway were upregulated in MUC16-stimulated neutrophils, accompanied by high expression of immunosuppression-related factors HHLA2, IL-6, TNFRSF9, ADORA2A, CD274 (PD-L1), and IDO1. NK cytotoxicity was decreased when treated by supernanant of MUC16-stimulated neutrophils in vitro.

CONCLUSION

MUC16 acted on neutrophils by Siglec-9 leading to an inflammatory and immunosuppressive phenotype in ovarian cancer.

TSC22D3 as an immune-related prognostic biomarker for acute myeloid leukemia

Acute myeloid leukemia (AML) is the type of hematologic neoplasm most common in adults. Glucocorticoid-induced gene TSC22D3 regulates cell proliferation through its function as a transcription factor. However, there is no consensus on the prognostic and immunoregulatory significance of TSC22D3 in AML. In the present study, we evaluated the correlation between TSC22D3 expression, immunoinfiltration, and prognostic significance in AML. Knockdown of TSC22D3 significantly attenuated the proliferation of Hel cells and increased sensitivity to cytarabine (Ara-c) drugs. Furthermore, TSC22D3 reduced the release of interleukin-1β (IL-1β) by inhibiting the NF-κB/NLRP3 signaling pathway, thereby inhibiting macrophage polarization to M1 subtype, and attenuating the pro-inflammatory tumor microenvironment. In conclusion, this study identified TSC22D3 as an immune-related prognostic biomarker for AML patients and suggested that therapeutic targeting of TSC22D3 may be a potential treatment option for AML through tumor immune escape.

CD271 activation prevents low to high-risk progression of cutaneous squamous cell carcinoma and improves therapy outcomes

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) is the second most prevalent form of skin cancer, showing a rapid increasing incidence worldwide. Although most cSCC can be cured by surgery, a sizeable number of cases are diagnosed at advanced stages, with local invasion and distant metastatic lesions. In the skin, neurotrophins (NTs) and their receptors (CD271 and Trk) form a complex network regulating epidermal homeostasis. Recently, several works suggested a significant implication of NT receptors in cancer. However, CD271 functions in epithelial tumors are controversial and its precise role in cSCC is still to be defined.

METHODS

Spheroids from cSCC patients with low-risk (In situ or Well-Differentiated cSCC) or high-risk tumors (Moderately/Poorly Differentiated cSCC), were established to explore histological features, proliferation, invasion abilities, and molecular pathways modulated in response to CD271 overexpression or activation in vitro. The effect of CD271 activities on the response to therapeutics was also investigated. The impact on the metastatic process and inflammation was explored in vivo and in vitro, by using zebrafish xenograft and 2D/3D models.

RESULTS

Our data proved that CD271 is upregulated in Well-Differentiated tumors as compared to the more aggressive Moderately/Poorly Differentiated cSCC, both in vivo and in vitro. We demonstrated that CD271 activities reduce proliferation and malignancy marker expression in patient-derived cSCC spheroids at each tumor grade, by increasing neoplastic cell differentiation. CD271 overexpression significantly increases cSCC spheroid mass density, while it reduces their weight and diameter, and promotes a major fold-enrichment in differentiation and keratinization genes. Moreover, both CD271 overexpression and activation decrease cSCC cell invasiveness in vitro. A significant inhibition of the metastatic process by CD271 was observed in a newly established zebrafish cSCC model. We found that the recruitment of leucocytes by CD271-overexpressing cells directly correlates with tumor killing and this finding was further highlighted by monocyte infiltration in a THP-1-SCC13 3D model. Finally, CD271 activity synergizes with Trk receptor inhibition, by reducing spheroid viability, and significantly improves the outcome of photodynamic therapy (PTD) or chemotherapy in spheroids and zebrafish.

CONCLUSION

Our study provides evidence that CD271 could prevent the switch between low to high-risk cSCC tumors. Because CD271 contributes to maintaining active differentiative paths and favors the response to therapies, it might be a promising target for future pharmaceutical development.

Uptake of tumor-derived microparticles induces metabolic reprogramming of macrophages in the early metastatic lung

Pre-metastatic niche formation is a critical step during the metastatic spread of cancer. One way by which primary tumors prime host cells at future metastatic sites is through the shedding of tumor-derived microparticles as a consequence of vascular sheer flow. However, it remains unclear how the uptake of such particles by resident immune cells affects their phenotype and function. Here, we show that ingestion of tumor-derived microparticles by macrophages induces a rapid metabolic and phenotypic switch that is characterized by enhanced mitochondrial mass and function, increased oxidative phosphorylation, and upregulation of adhesion molecules, resulting in reduced motility in the early metastatic lung. This reprogramming event is dependent on signaling through the mTORC1, but not the mTORC2, pathway and is induced by uptake of tumor-derived microparticles. Together, these data support a mechanism by which uptake of tumor-derived microparticles induces reprogramming of macrophages to shape their fate and function in the early metastatic lung.

The NR_109/FUBP1/c-Myc axis regulates TAM polarization and remodels the tumor microenvironment to promote cancer development

BACKGROUND

Tumor-associated macrophages (TAMs) are a major component of the tumor microenvironment (TME) and exert an important role in tumor progression. Due to the heterogeneity and plasticity of TAMs, modulating the polarization states of TAMs is considered as a potential therapeutic strategy for tumors. Long noncoding RNAs (lncRNAs) have been implicated in various physiological and pathological processes, yet the underlying mechanism on how lncRNAs manipulate the polarization states of TAMs is still unclear and remains to be further investigated.

METHODS

Microarray analyses were employed to characterize the lncRNA profile involved in THP-1-induced M0, M1 and M2-like macrophage. Among those differentially expressed lncRNAs, NR_109 was further studied, for its function in M2-like macrophage polarization and the effects of the condition medium or macrophages mediated by NR_109 on tumor proliferation, metastasis and TME remodeling both in vitro and in vivo. Moreover, we revealed how NR_109 interacted with far upstream element-binding protein 1 (FUBP1) to regulate the protein stability through hindering ubiquitination modification by competitively binding with JVT-1. Finally, we examined sections of tumor patients to probe the correlation among the expression of NR_109 and related proteins, showing the clinical significance of NR_109.

RESULTS

We found that lncRNA NR_109 was highly expressed in M2-like macrophages. Knockdown NR_109 impeded IL-4 induced M2-like macrophage polarization and significantly reduced the activity of M2-like macrophages to support the proliferation and metastasis of tumor cells in vitro and in vivo. Mechanistically, NR_109 competed with JVT-1 to bind FUBP1 at its C-terminus domain, impeded the ubiquitin-mediated degradation of FUBP1, activated c-Myc transcription and thus promoted M2-like macrophages polarization. Meanwhile, as a transcription factor, c-Myc could bind to the promoter of NR_109 and enhance the transcription of NR_109. Clinically, high NR_109 expression was found in CD163⁺ TAMs from tumor tissues and was positively correlated with poor clinical stages of patients with gastric cancer and breast cancer.

CONCLUSIONS

Our work revealed for the first time that NR_109 exerted a crucial role in regulating the phenotype-remodeling and function of M2-like macrophages via a NR_109/FUBP1/c-Myc positive feedback loop. Thus, NR_109 has great translational potentials in the diagnosis, prognosis and immunotherapy of cancer.

Extracellular vesicles as next generation immunotherapeutics

Extracellular vesicles (EVs) function as a mode of intercellular communication and molecular transfer to elicit diverse biological/functional response. Accumulating evidence has highlighted that EVs from immune, tumour, stromal cells and even bacteria and parasites mediate the communication of various immune cell types to dynamically regulate host immune response. EVs have an innate capacity to evade recognition, transport and transfer functional components to target cells, with subsequent removal by the immune system, where the immunological activities of EVs impact immunoregulation including modulation of antigen presentation and cross-dressing, immune activation, immune suppression, and immune surveillance, impacting the tumour immune microenvironment. In this review, we outline the recent progress of EVs in immunorecognition and therapeutic intervention in cancer, including vaccine and targeted drug delivery and summarise their utility towards clinical translation. We highlight the strategies where EVs (natural and engineered) are being employed as a therapeutic approach for immunogenicity, tumoricidal function, and vaccine development, termed immuno-EVs. With seminal studies providing significant progress in the sequential development of engineered EVs as therapeutic anti-tumour platforms, we now require direct assessment to tune and improve the efficacy of resulting immune responses - essential in their translation into the clinic. We believe such a review could strengthen our understanding of the progress in EV immunobiology and facilitate advances in engineering EVs for the development of novel EV-based immunotherapeutics as a platform for cancer treatment.

ChemoNETosis: A road to tumor therapeutic resistance

Neutrophil extracellular traps (NETs) limit infection by trapping microorganisms and have recently been shown to induce tumor metastasis. In this issue of Cancer Cell, Mousset et al. illustrate how chemotherapy-induced inflammation confers chemoresistance by facilitating NETosis in malignant tumors, highlighting a therapeutic opportunity to target inflammatory NETs in cancer treatment.

ETV4 Mediated Tumor-Associated Neutrophil Infiltration Facilitates Lymphangiogenesis and Lymphatic Metastasis of Bladder Cancer

As a key step of tumor lymphatic metastasis, lymphangiogenesis is regulated by VEGFC-VEGFR3 signaling pathway mediated by immune cells, mainly macrophages, in the tumor microenvironment. However, little is known whether tumor associated neutrophils are involved in lymphangiogenesis. Here, it is found that TANs infiltration is increased in LN-metastatic BCa and is associated with poor prognosis. Neutrophil depletion results in significant reduction in popliteal LN metastasis and lymphangiogenesis. Mechanistically, transcription factor ETV4 enhances BCa cells-derived CXCL1/8 to recruit TANs, leading to the increase of VEGFA and MMP9 from TANs, and then facilitating lymphangiogenesis and LN metastasis of BCa. Moreover, phosphorylation of ETV4 at tyrosine 392 by tyrosine kinase PTK6 increases nuclear translocation of ETV4 and is essential for its function in BCa. Overall, the findings reveal a novel mechanism of how tumor cells regulate TANs-induced lymphangiogenesis and LN metastasis and identify ETV4 as a therapeutic target of LN metastasis in BCa.

Circulating tumour cells in gastrointestinal cancers: food for thought?

Gastrointestinal (GI) cancers account for 35% of cancer-related deaths, predominantly due to their ability to spread and generate drug-tolerant metastases. Arising from different locations in the GI system, the majority of metastatic GI malignancies colonise the liver and the lungs. In this context, circulating tumour cells (CTCs) are playing a critical role in the formation of new metastases, and their presence in the blood of patients has been correlated with a poor outcome. In addition to their prognostic utility, prospective targeting of CTCs may represent a novel, yet ambitious strategy in the fight against metastasis. A better understanding of CTC biology, mechanistic underpinnings and weaknesses may facilitate the development of previously underappreciated anti-metastasis approaches. Here, along with related clinical studies, we outline a selection of the literature describing biological features of CTCs with an impact on their metastasis forming ability in different GI cancers.

Roles of macrophages on ulcerative colitis and colitis-associated colorectal cancer

Colitis-associated colorectal cancer is the most serious complication of ulcerative colitis. Long-term chronic inflammation increases the incidence of CAC in UC patients. Compared with sporadic colorectal cancer, CAC means multiple lesions, worse pathological type and worse prognosis. Macrophage is a kind of innate immune cell, which play an important role both in inflammatory response and tumor immunity. Macrophages are polarized into two phenotypes under different conditions: M1 and M2. In UC, enhanced macrophage infiltration produces a large number of inflammatory cytokines, which promote tumorigenesis of UC. M1 polarization has an anti-tumor effect after CAC formation, whereas M2 polarization promotes tumor growth. M2 polarization plays a tumor-promoting role. Some drugs have been shown to that prevent and treat CAC effectively by targeting macrophages.

The evolving tumor microenvironment: From cancer initiation to metastatic outgrowth

Cancers represent complex ecosystems comprising tumor cells and a multitude of non-cancerous cells, embedded in an altered extracellular matrix. The tumor microenvironment (TME) includes diverse immune cell types, cancer-associated fibroblasts, endothelial cells, pericytes, and various additional tissue-resident cell types. These host cells were once considered bystanders of tumorigenesis but are now known to play critical roles in the pathogenesis of cancer. The cellular composition and functional state of the TME can differ extensively depending on the organ in which the tumor arises, the intrinsic features of cancer cells, the tumor stage, and patient characteristics. Here, we review the importance of the TME in each stage of cancer progression, from tumor initiation, progression, invasion, and intravasation to metastatic dissemination and outgrowth. Understanding the complex interplay between tumor cell-intrinsic, cell-extrinsic, and systemic mediators of disease progression is critical for the rational development of effective anti-cancer treatments.

A timeline of tumour-associated macrophage biology

Tumour progression is modulated by the local microenvironment. This environment is populated by many immune cells, of which macrophages are among the most abundant. Clinical correlative data and a plethora of preclinical studies in mouse models of cancers have shown that tumour-associated macrophages (TAMs) play a cancer-promoting role. Within the primary tumour, TAMs promote tumour cell invasion and intravasation and tumour stem cell viability and induce angiogenesis. At the metastatic site, metastasis-associated macrophages promote extravasation, tumour cell survival and persistent growth, as well as maintain tumour cell dormancy in some contexts. In both the primary and metastatic sites, TAMs are suppressive to the activities of cytotoxic T and natural killer cells that have the potential to eradicate tumours. Such activities suggest that TAMs will be a major target for therapeutic intervention. In this Perspective article, we chronologically explore the evolution of our understanding of TAM biology put into the context of major enabling advances in macrophage biology.

The pleiotropic mode and molecular mechanism of macrophages in promoting tumor progression and metastasis

Macrophages are the most abundant immune cells in primary and metastatic tumor tissues. Studies have shown that macrophages mainly exhibit a tumor-promoting phenotype and play a key role in tumor progression and metastasis. Therefore, many macrophage-targeted drugs have entered clinical trials. However, compared to preclinical studies, some clinical trial results showed that macrophage-targeted therapy did not achieve the desired effect. This may be because most of what we know about macrophages comes from in vitro experiments and animal models, while macrophages in the more complex human microenvironment are still poorly understood. With the development of technologies such as single-cell RNA sequencing, we have gained a new understanding of the origin, classification and functional mechanism of tumor-associated macrophages. Therefore, this study reviewed the recent progress of macrophages in promoting tumor progression and metastasis, aiming to provide some help for the formulation of optimal strategies for macrophage-targeted therapy.

No NETs no TIME: Crosstalk between neutrophil extracellular traps and the tumor immune microenvironment

The tumor immune microenvironment (TIME) controls tumorigenesis. Neutrophils are important components of TIME and control tumor progression and therapy resistance. Neutrophil extracellular traps (NETs) ejected by activated neutrophils are net-like structures composed of decondensed extracellular chromatin filaments decorated with a plethora of granules as well as cytoplasmic proteins. Many of these harbour post translational modifications. Cancer cells reportedly trigger NET formation, and conversely, NETs alter the TIME and promote tumor cell proliferation and migration. The specific interactions between NETs and TIME and the respective effects on tumor progression are still elusive. In certain tumors, a CD4⁺ T helper (Th) 2 cell-associated TIME induces NETs and exerts immunosuppressive functions via programmed death 1 (PD-1)/PD-L1, both associated with poorer prognosis. In other cases, NETs induce the proliferation of Th1 cells, associated with an improved prognosis in cancer. In addition, NETs can drive macrophage polarization and often rely on macrophages to promote cancer cell invasion and metastasis. In turn, macrophages can swiftly clear NETs in an immunologically silent manner. The aim of this review is to summarize the knowledge about the mutual interaction between NETs and TIME and its impact on tumor growth and therapy.

M2-like macrophage-derived exosomes facilitate metastasis in non-small-cell lung cancer by delivering integrin αVβ3

Metastasis is the most prevalent cause of cancer deaths, and immunological components of the tumor microenvironment, especially tumor-associated macrophages (TAMs), play a vital role in cancer metastasis. However, the underlying mechanisms of TAMs on non-small-cell lung cancer (NSCLC) metastasis remain largely unexplored. Herein, we demonstrated that M2-like TAMs facilitate the migration and invasion of cancer cells in vitro and in vivo through intercellular delivery of M2-like macrophage-derived exosomes (M2-exos). Importantly, we found that M2-exos had considerably higher levels of integrin (ITG) αV and β3. The impact of M2-like macrophage-mediated invasion and migration of NSCLC cells was clearly decreased when ITG αVβ3 was blocked. Mechanistically, exosomal ITG αVβ3 produced from M2-like macrophages successfully triggered the focal adhesion kinase signaling pathway in recipient cells, boosting the migratory and invasive abilities of NSCLC cells. Clinically, we found that metastatic NSCLC patients had greater ITG αV and β3 expression, which was associated with a worse prognosis. This study reveals a novel mechanism by which M2-exos significantly increased NSCLC cell migration and invasion by delivering integrin αVβ3. Exosomal ITG αVβ3 can be used as a potential prognostic marker, and blocking ITG αVβ3 could be a viable treatment option for preventing tumor metastasis.

An injectable vitreous substitute with sustained release of metformin for enhanced uveal melanoma immunotherapy

Uveal melanoma (UM) is the most prevalent primary intraocular malignant tumor in adults with a high rate of metastasis. Conventional treatments have limited effects on metastasis and cause permanent ocular tissue defects. Here, a novel strategy based on an injectable vitreous substitute with sustained metformin release ability (IVS-Met) was reported for efficient UM therapy as well as for repairing vitreous deficiency and preserving visual function. IVS-Met showed an excellent long-term anti-tumor effect by direct tumor attack and modulation of the tumor microenvironment (TME). IVS-Met reduced the proportion of pro-tumor M2 tumor-associated macrophages and induced the pro-inflammatory M1 phenotype, thus reversing the immunosuppressive TME and eliciting robust anti-tumor immune responses. Notably, IVS-Met demonstrated high performance in the inhibition of UM metastasis and significantly extended the survival time of mice. In addition, the vitreous substitute achieved facile administration via direct injection and exhibited excellent rheological and optical properties with the key parameters very close to those of the vitreous body to repair vitreous deficiency and preserve visual function. In summary, this strategy has realized effective UM treatment while retaining eyeballs and vision for the first time, revealing great potential for translation to clinical practice.

Biophysical heterogeneity of myeloid-derived microenvironment to regulate resistance to cancer immunotherapy

Despite the advances in immunotherapy for cancer treatment, patients still obtain limited benefits, mostly owing to unrestrained tumour self-expansion and immune evasion that exploits immunoregulatory mechanisms. Traditionally, myeloid cells have a dominantly immunosuppressive role. However, the complicated populations of the myeloid cells and their multilateral interactions with tumour/stromal/lymphoid cells and physical abnormalities in the tumour microenvironment (TME) determine their heterogeneous functions in tumour development and immune response. Tumour-associated myeloid cells (TAMCs) include monocytes, tumour-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), dendritic cells (DCs), and granulocytes. Single-cell profiling revealed heterogeneous TAMCs composition, sub-types, and transcriptomic signatures across 15 human cancer types. We systematically reviewed the biophysical heterogeneity of TAMC composition and pro/anti-tumoral and immuno-suppressive/stimulating properties of myeloid-derived microenvironments. We also summarised comprehensive clinical strategies to overcome resistance to immunotherapy from three dimensions: targeting TAMCs, reversing physical abnormalities, utilising nanomedicines, and finally, put forward futuristic perspectives for scientific and clinical research.

Small Molecular Inhibitors Reverse Cancer Metastasis by Blockading Oncogenic PITPNM3

Most cancer-related deaths are a result of metastasis. The development of small molecular inhibitors reversing cancer metastasis represents a promising therapeutic opportunity for cancer patients. This pan-cancer analysis identifies oncogenic roles of membrane-associated phosphatidylinositol transfer protein 3 (PITPNM3), which is crucial for cancer metastasis. Small molecules targeting PITPNM3 must be explored further. Here, PITPNM3-selective small molecular inhibitors are reported. These compounds exhibit target-specific inhibition of PITPNM3 signaling, thereby reducing metastasis of breast cancer cells. Besides, by using nanoparticle-based delivery systems, these PITPNM3-selective compounds loaded nanoparticles significantly repress metastasis of breast cancer in mouse xenograft models and organoid models. Notably, the results establish an important metastatic-promoting role for PITPNM3 and offer PITPNM3 inhibition as a therapeutic strategy in metastatic breast cancer.

Junctional adhesion molecule-A is dispensable for myeloid cell recruitment and diversification in the tumor microenvironment

Junctional adhesion molecule-A (JAM-A), expressed on the surface of myeloid cells, is required for extravasation at sites of inflammation and may also modulate myeloid cell activation. Infiltration of myeloid cells is a common feature of tumors that drives disease progression, but the function of JAM-A in this phenomenon and its impact on tumor-infiltrating myeloid cells is little understood. Here we show that systemic cancer-associated inflammation in mice enhanced JAM-A expression selectively on circulating monocytes in an IL1β-dependent manner. Using myeloid-specific JAM-A-deficient mice, we found that JAM-A was dispensable for recruitment of monocytes and other myeloid cells to tumors, in contrast to its reported role in inflammation. Single-cell RNA sequencing revealed that loss of JAM-A did not influence the transcriptional reprogramming of myeloid cells in the tumor microenvironment. Overall, our results support the notion that cancer-associated inflammation can modulate the phenotype of circulating immune cells, and we demonstrate that tumors can bypass the requirement of JAM-A for myeloid cell recruitment and reprogramming.

Tumor-on-a-chip: Perfusable vascular incorporation brings new approach to tumor metastasis research and drug development

The extracellular matrix interacts with cancer cells and is a key factor in the development of cancer. Traditional two-dimensional models cannot mimic the natural in situ environment of cancer tissues, whereas three-dimensional (3D) models such as spherical culture, bioprinting, and microfluidic approaches can achieve in vitro reproduction of certain structures and components of the tumor microenvironment, including simulation of the hypoxic environment of tumor tissue. However, the lack of a perfusable vascular network is a limitation of most 3D models. Solid tumor growth and metastasis require angiogenesis, and tumor models with microvascular networks have been developed to better understand underlying mechanisms. Tumor-on-a-chip technology combines the advantages of microfluidics and 3D cell culture technology for the simulation of tumor tissue complexity and characteristics. In this review, we summarize progress in constructing tumor-on-a-chip models with efficiently perfused vascular networks. We also discuss the applications of tumor-on-a-chip technology to studying the tumor microenvironment and drug development. Finally, we describe the creation of several common tumor models based on this technology to provide a deeper understanding and new insights into the design of vascularized cancer models. We believe that the tumor-on-a-chip approach is an important development that will provide further contributions to the field.

Effects of gut microbiota on immune responses and immunotherapy in colorectal cancer

Accumulating evidence suggests that gut microbial dysbiosis is implicated in colorectal cancer (CRC) initiation and progression through interaction with host immune system. Given the intimate relationship between the gut microbiota and the antitumor immune responses, the microbiota has proven to be effective targets in modulating immunotherapy responses of preclinical CRC models. However, the proposed putative mechanisms of how these bacteria affect immune responses and immunotherapy efficacy remains obscure. In this review, we summarize recent findings of clinical gut microbial dysbiosis in CRC patients, the reciprocal interactions between gut microbiota and the innate and/or the adaptive immune system, as well as the effect of gut microbiota on immunotherapy response in CRC. Increased understanding of the gut microbiota-immune system interactions will benefit the rational application of microbiota to the clinical promising biomarker or therapeutic strategy as a cancer immunotherapy adjuvant.

The impact of VEGF on cancer metastasis and systemic disease

Metastasis is the leading cause of cancer-associated mortality and the underlying mechanisms of cancer metastasis remain elusive. Both blood and lymphatic vasculatures are essential structures for mediating distal metastasis. The vasculature plays multiple functions, including accelerating tumor growth, sustaining the tumor microenvironment, supplying growth and invasive signals, promoting metastasis, and causing cancer-associated systemic disease. VEGF is one of the key angiogenic factors in tumors and participates in the initial stage of tumor development, progression and metastasis. Consequently, VEGF and its receptor-mediated signaling pathways have become one of the most important therapeutic targets for treating various cancers. Today, anti-VEGF-based antiangiogenic drugs (AADs) are widely used in the clinic for treating different types of cancer in human patients. Despite nearly 20-year clinical experience with AADs, the impact of these drugs on cancer metastasis and systemic disease remains largely unknown. In this review article, we focus our discussion on tumor VEGF in cancer metastasis and systemic disease and mechanisms underlying AADs in clinical benefits.

A Targetable Myeloid Inflammatory State Governs Disease Recurrence in Clear-Cell Renal Cell Carcinoma

It is poorly understood how the tumor immune microenvironment influences disease recurrence in localized clear-cell renal cell carcinoma (ccRCC). Here we performed whole-transcriptomic profiling of 236 tumors from patients assigned to the placebo-only arm of a randomized, adjuvant clinical trial for high-risk localized ccRCC. Unbiased pathway analysis identified myeloid-derived IL6 as a key mediator. Furthermore, a novel myeloid gene signature strongly correlated with disease recurrence and overall survival on uni- and multivariate analyses and is linked to TP53 inactivation across multiple data sets. Strikingly, effector T-cell gene signatures, infiltration patterns, and exhaustion markers were not associated with disease recurrence. Targeting immunosuppressive myeloid inflammation with an adenosine A2A receptor antagonist in a novel, immunocompetent, Tp53-inactivated mouse model significantly reduced metastatic development. Our findings suggest that myeloid inflammation promotes disease recurrence in ccRCC and is targetable as well as provide a potential biomarker-based framework for the design of future immuno-oncology trials in ccRCC.

SIGNIFICANCE

Improved understanding of factors that influence metastatic development in localized ccRCC is greatly needed to aid accurate prediction of disease recurrence, clinical decision-making, and future adjuvant clinical trial design. Our analysis implicates intratumoral myeloid inflammation as a key driver of metastasis in patients and a novel immunocompetent mouse model. This article is highlighted in the In This Issue feature, p. 2221.

Prognostic value of lactate transporter SLC16A1 and SLC16A3 as oncoimmunological biomarkers associating tumor metabolism and immune evasion in glioma

BACKGROUND

Hypoxic microenvironment is immunosuppressive and protumorigenic, and elevated lactate is an intermediary in the modulation of immune responses. However, as critical lactate transporters, the role of SLC16A1 and SLC16A3 in immune infiltration and evasion of glioma is not fully elucidated.

METHODS

Gene expression in low- and high-grade glioma (LGG and GBM) was evaluated with TCGA database. The TISIDB, TIMER and CIBERSORT databases were utilized for the analysis of the correlation between SLC16A1 or SLC16A3 and immunocyte infiltration as well as immune checkpoints.

RESULTS

Compared with normal tissues, a significant increase of both SLC16A1 and SLC16A3 was found in LGG and GBM, and closely related to the poor prognosis only in LGG. Cancer SEA indicated that SLC16A1 was involved in hypoxia while SLC16A3 contributed to metastasis and inflammation in glioma. The SLC16A3 expression was significantly correlated with neutrophil activation by GO analysis. TISCH showed the distribution of SLC16A1 on glioma cells and SLC16A3 on immune cells, which was correlated to tumor-associated macrophages and neutrophils that are immunosuppressive. SLC16A1 and SLC16A3 were identified to tightly interacted with diverse immune checkpoints (especially PD1, PD-L1, PD-L2, Tim-3) and immunosuppressive factors (TGF-β and IL-10) in glioma. Furthermore, SLC16A3 had a positive correlation to activation markers of tumor-associated neutrophils and chemokines such as CCL2, CCL22, CXCR2, CXCR4 in LGG and CCL7, CCL20 CXCL8 in GBM, which could enhance infiltration of immunosuppressive cells to the tumor microenvironment.

CONCLUSION

In general, our results suggest that SLC16A1 and SLC16A3 act as a bridge between tumor metabolism and immunity by promoting immunosuppressive cell infiltration, which contributes to immune evasion and a worse prognosis in glioma. Targeting SLC16A1 and SLC16A3 may provide novel therapeutic strategy for immunotherapy in glioma.

GP, Gopalakrishnan AV. Role of Immune Cells and Receptors in Cancer Treatment: An Immunotherapeutic Approach

Cancer immunotherapy moderates the immune system’s ability to fight cancer. Due to its extreme complexity, scientists are working to put together all the puzzle pieces to get a clearer picture of the immune system. Shreds of available evidence show the connection between cancer and the immune system. Immune responses to tumors and lymphoid malignancies are influenced by B cells, γδT cells, NK cells, and dendritic cells (DCs). Cancer immunotherapy, which encompasses adoptive cancer therapy, monoclonal antibodies (mAbs), immune checkpoint therapy, and CART cells, has revolutionized contemporary cancer treatment. This article reviews recent developments in immune cell regulation and cancer immunotherapy. Various options are available to treat many diseases, particularly cancer, due to the progress in various immunotherapies, such as monoclonal antibodies, recombinant proteins, vaccinations (both preventative and curative), cellular immunotherapies, and cytokines.

Emerging strategies in targeting tumor-resident myeloid cells for cancer immunotherapy

Immune checkpoint inhibitors targeting programmed cell death protein 1, programmed death-ligand 1, and cytotoxic T-lymphocyte-associated protein 4 provide deep and durable treatment responses which have revolutionized oncology. However, despite over 40% of cancer patients being eligible to receive immunotherapy, only 12% of patients gain benefit. A key to understanding what differentiates treatment response from non-response is better defining the role of the innate immune system in anti-tumor immunity and immune tolerance. Teleologically, myeloid cells, including macrophages, dendritic cells, monocytes, and neutrophils, initiate a response to invading pathogens and tissue repair after pathogen clearance is successfully accomplished. However, in the tumor microenvironment (TME), these innate cells are hijacked by the tumor cells and are imprinted to furthering tumor propagation and dissemination. Major advancements have been made in the field, especially related to the heterogeneity of myeloid cells and their function in the TME at the single cell level, a topic that has been highlighted by several recent international meetings including the 2021 China Cancer Immunotherapy workshop in Beijing. Here, we provide an up-to-date summary of the mechanisms by which major myeloid cells in the TME facilitate immunosuppression, enable tumor growth, foster tumor plasticity, and confer therapeutic resistance. We discuss ongoing strategies targeting the myeloid compartment in the preclinical and clinical settings which include: (1) altering myeloid cell composition within the TME; (2) functional blockade of immune-suppressive myeloid cells; (3) reprogramming myeloid cells to acquire pro-inflammatory properties; (4) modulating myeloid cells via cytokines; (5) myeloid cell therapies; and (6) emerging targets such as Siglec-15, TREM2, MARCO, LILRB2, and CLEVER-1. There is a significant promise that myeloid cell-based immunotherapy will help advance immuno-oncology in years to come.

New opportunities for immunomodulation of the tumour microenvironment using chemical tools

Immunotherapy is recognised as an attractive method for the treatment of cancer, and numerous treatment strategies have emerged over recent years. Investigations of the tumour microenvironment (TME) have led to the identification of many potential therapeutic targets and methods. However, many recently applied immunotherapies are based on previously identified strategies, such as boosting the immune response by combining commonly used stimulators, and the release of drugs through changes in pH. Although methodological improvements such as structural optimisation and combining strategies can be undertaken, applying those novel targets and methods in immunotherapy remains an important goal. In this review, we summarise the latest research on the TME, and discuss how small molecules, immune cells, and their interactions with tumour cells can be regulated in the TME. Additionally, the techniques currently employed for delivery of these agents to the TME are also mentioned. Strategies to modulate cell phenotypes and interactions between immune cells and tumours are mainly discussed. We consider both modulatory and targeting methods aiming to bridge the gap between the TME and chemical modulation thereof.

Roles of tumor-associated neutrophils in tumor metastasis and its clinical applications

Metastasis, a primary cause of death in patients with malignancies, is promoted by intrinsic changes in both tumor and non-malignant cells in the tumor microenvironment (TME). As major components of the TME, tumor-associated neutrophils (TANs) promote tumor progression and metastasis through communication with multiple growth factors, chemokines, inflammatory factors, and other immune cells, which together establish an immunosuppressive TME. In this review, we describe the potential mechanisms by which TANs participate in tumor metastasis based on recent experimental evidence. We have focused on drugs in chemotherapeutic regimens that target TANs, thereby providing a promising future for cancer immunotherapy.

Macrophages as tools and targets in cancer therapy

Tumour-associated macrophages are an essential component of the tumour microenvironment and have a role in the orchestration of angiogenesis, extracellular matrix remodelling, cancer cell proliferation, metastasis and immunosuppression, as well as in resistance to chemotherapeutic agents and checkpoint blockade immunotherapy. Conversely, when appropriately activated, macrophages can mediate phagocytosis of cancer cells and cytotoxic tumour killing, and engage in effective bidirectional interactions with components of the innate and adaptive immune system. Therefore, they have emerged as therapeutic targets in cancer therapy. Macrophage-targeting strategies include inhibitors of cytokines and chemokines involved in the recruitment and polarization of tumour-promoting myeloid cells as well as activators of their antitumorigenic and immunostimulating functions. Early clinical trials suggest that targeting negative regulators (checkpoints) of myeloid cell function indeed has antitumor potential. Finally, given the continuous recruitment of myelomonocytic cells into tumour tissues, macrophages are candidates for cell therapy with the development of chimeric antigen receptor effector cells. Macrophage-centred therapeutic strategies have the potential to complement, and synergize with, currently available tools in the oncology armamentarium.

Macrophages can promote tumorigenesis and enhance the antitumour response. This Review discusses the molecular mechanisms underlying the reprogramming of macrophages in the tumour microenvironment and provides an overview of macrophage-targeted therapies for the treatment of cancer.

The Role of Adipokines in Pancreatic Cancer

In modern society, inappropriate diets and other lifestyle habits have made obesity an increasingly prominent health problem. Pancreatic cancer (PC), a kind of highly aggressive malignant tumor, is known as a silent assassin and is the seventh leading cause of cancer death worldwide, pushing modern medicine beyond help. Adipokines are coming into notice because of the role of the intermediate regulatory junctions between obesity and malignancy. This review summarizes the current evidence for the relationship between highly concerning adipokines and the pathogenesis of PC. Not only are classical adipokines such as leptin and adiponectin included, but they also cover the recognized chemerin and osteopontin. Through a summary of the biological functions of these adipokines as well as their receptors, it was discovered that in addition to their basic function of stimulating the biological activity of tumors, more studies confirm that adipokines intervene in the progression of PC from the viewpoint of tumor metabolism, immune escape, and reprogramming of the tumor microenvironment (TME). Besides endocrine function, the impact of white adipose tissue (WAT)-induced chronic inflammation on PC is briefly discussed. Furthermore, the potential implication of the acknowledged endocrine behavior of brown adipose tissue (BAT) in relation to carcinogenesis is also explored. No matter the broad spectrum of obesity and the poor prognosis of PC, supplemental research is needed to unravel the detailed network of adipokines associated with PC. Exploiting profound therapeutic strategies that target adipokines and their receptors may go some way to improving the current worrying prognosis of PC patients.

Neutrophils: New Critical Regulators of Glioma

In cancer, neutrophils are an important part of the tumour microenvironment (TME). Previous studies have shown that circulating and infiltrating neutrophils are associated with malignant progression and immunosuppression in gliomas. However, recent studies have shown that neutrophils have an antitumour effect. In this review, we focus on the functional roles of neutrophils in the circulation and tumour sites in patients with glioma. The mechanisms of neutrophil recruitment, immunosuppression and the differentiation of neutrophils are discussed. Finally, the potential of neutrophils as clinical biomarkers and therapeutic targets is highlighted. This review can help us gain a deeper and systematic understanding of the role of neutrophils, and provide new insights for treatment in gliomas.

Macrophage diversity in cancer revisited in the era of single-cell omics

Tumor-associated macrophages (TAMs) have multiple potent functions in cancer and, thus, represent important therapeutic targets. These diverse functions highlight the heterogenous nature of TAMs. Recent single cell omics technologies have significantly advanced our understanding of the molecular diversity of TAMs. However, a unifying nomenclature of TAM diversity and annotation of their molecular signatures is lacking. Here, we review recent major studies of single cell transcriptome, epigenome, metabolome, and spatial omics of cancer with a specific focus on TAMs. We also propose a consensus model of TAM diversity and present avenues for future research.

Lymphatic vessels in cancer

The lymphatic system, composed of initial and collecting lymphatic vessels as well as lymph nodes that are present in almost every tissue of the human body, acts as an essential transport system for fluids, biomolecules and cells between peripheral tissues and the central circulation. Consequently, it is required for normal body physiology but is also involved in the pathogenesis of various diseases, most notably cancer. The important role of tumor-associated lymphatic vessels and lymphangiogenesis in the formation of lymph node metastasis has been elucidated during the last two decades, whereas the underlying mechanisms and the relation between lymphatic and peripheral organ dissemination of cancer cells are incompletely understood. Lymphatic vessels are also important for tumor-host communication, relaying molecular information from a primary or metastatic tumor to regional lymph nodes and the circulatory system. Beyond antigen transport, lymphatic endothelial cells, particularly those residing in lymph node sinuses, have recently been recognized as direct regulators of tumor immunity and immunotherapy responsiveness, presenting tumor antigens and expressing several immune-modulatory signals including PD-L1. In this review, we summarize recent discoveries in this rapidly evolving field and highlight strategies and challenges of therapeutic targeting of lymphatic vessels or specific lymphatic functions in cancer patients.

Mapping the Tumor Microenvironment in TNBC and Deep Exploration for M1 Macrophages-Associated Prognostic Genes

Triple negative breast cancer (TNBC) remains the worst molecular subtype due to high heterogeneity and lack of effective therapeutic targets. Here we investigated the tumor and immune microenvironment heterogeneity of TNBC using scRNA-seq and bulk RNA-seq data from public databases and our cohort. Macrophage subpopulations accounted for a high proportion of tumor immune microenvironment (TIME), and M1 macrophages were associated with better clinical outcomes. Furthermore, three maker genes including IFI35, PSMB9, and SAMD9L showed a close connection with M1 macrophages. Specifically, IFI35 was positively associated with macrophage activation, chemotaxis, and migration. Also, patients with high IFI35 expression had a better prognosis. In vitro studies subsequently demonstrated that IFI35 was upregulated during the M1 subtype differentiation of macrophages. In summary, our data suggested that IFI35 maybe a promising novel target that helps to reshape macrophage polarization towards the M1 subtype for anti-tumor effects.

Single-cell RNA-seq dissecting heterogeneity of tumor cells and comprehensive dynamics in tumor microenvironment during lymph nodes metastasis in gastric cancer

Lymph node metastasis is the common metastasis route of gastric cancer. However, until now, heterogeneities of tumor cells and tumor microenvironment in primary tumors (PT) and metastatic lymph nodes (MLN) of gastric cancer (GC) remains uncharacterized. In this study, scRNA-seq was performed on tissues from PT and MLN of gastric cancer. Trajectory analysis and function enrichment analyses were conducted to decode the underlying mechanisms contributing to LN metastasis of gastric cancer. Heterogeneous composition of immune cells and distant intercellular interactions in PT and MLN were analyzed. Based on the generated single cell transcriptome profiles, dynamics of gene expressions in cancer cells between PT and MLN were characterized. Moreover, we reconstructed the developmental trajectory of GC cells' metastasis to LN and identified two sub-types of GC cells with distinct potentials of having malignant biological behaviors. We characterized the repression of neutrophil polarization associated genes, like LCN2, which would contribute to LN metastasis, and histochemistry experiments validated our findings. Additionally, heterogeneity in neutrophils, rather than macrophages, was characterized. Immune checkpoint associated interaction of SPP1 was found active in MLN. In conclusion, we decode the dynamics of tumor cells during LN metastasis in GC and to identify a sub-type of GC cells with potentials of LN metastasis. Our data indicated that the disordering the neutrophils polarization and maturation and the activation of immune checkpoint SPP1 might contribute to LN metastasis in GC, providing a novel insight on the mechanism and potential therapeutic targets of LN metastasis in GC. This article is protected by copyright. All rights reserved.

The overall process of metastasis: From initiation to a new tumor

Metastasis-a process that involves the migration of cells from the primary site to distant organs-is the leading cause of cancer-associated death. Improved technology and in-depth research on tumors have furthered our understanding of the various mechanisms involved in tumor metastasis. Metastasis is initiated by cancer cells of a specific phenotype, which migrate with the assistance of extracellular components and metastatic traits conferred via epigenetic regulation while modifying their behavior in response to the complex and dynamic human internal environment. In this review, we have summarized the general steps involved in tumor metastasis and their characteristics, incorporating recent studies and topical issues, including epithelial-mesenchymal transition, cancer stem cells, neutrophil extracellular traps, pre-metastatic niche, extracellular vesicles, and dormancy. Several feasible treatment directions have also been summarized. In addition, the correlation between cancer metastasis and lifestyle factors, such as obesity and circadian rhythm, has been illustrated.

Immunosuppressive cells in cancer: mechanisms and potential therapeutic targets

Immunotherapies like the adoptive transfer of gene-engineered T cells and immune checkpoint inhibitors are novel therapeutic modalities for advanced cancers. However, some patients are refractory or resistant to these therapies, and the mechanisms underlying tumor immune resistance have not been fully elucidated. Immunosuppressive cells such as myeloid-derived suppressive cells, tumor-associated macrophages, tumor-associated neutrophils, regulatory T cells (Tregs), and tumor-associated dendritic cells are critical factors correlated with immune resistance. In addition, cytokines and factors secreted by tumor cells or these immunosuppressive cells also mediate the tumor progression and immune escape of cancers. Thus, targeting these immunosuppressive cells and the related signals is the promising therapy to improve the efficacy of immunotherapies and reverse the immune resistance. However, even with certain success in preclinical studies or in some specific types of cancer, large perspectives are unknown for these immunosuppressive cells, and the related therapies have undesirable outcomes for clinical patients. In this review, we comprehensively summarized the phenotype, function, and potential therapeutic targets of these immunosuppressive cells in the tumor microenvironment.

LFA-1 activation enriches tumor-specific T cells in a cold tumor model and synergizes with CTLA-4 blockade

The inability of CD8⁺ effector T cells (Teffs) to reach tumor cells is an important aspect of tumor resistance to cancer immunotherapy. The recruitment of these cells to the tumor microenvironment (TME) is regulated by integrins, a family of adhesion molecules that are expressed on T cells. Here, we show that 7HP349, a small-molecule activator of lymphocyte function–associated antigen-1 (LFA-1) and very late activation antigen-4 (VLA-4) integrin cell-adhesion receptors, facilitated the preferential localization of tumor-specific T cells to the tumor and improved antitumor response. 7HP349 monotherapy had modest effects on anti–programmed death 1–resistant (anti–PD-1–resistant) tumors, whereas combinatorial treatment with anti–cytotoxic T lymphocyte–associated protein 4 (anti–CTLA-4) increased CD8⁺ Teff intratumoral sequestration and synergized in cooperation with neutrophils in inducing cancer regression. 7HP349 intratumoral CD8⁺ Teff enrichment activity depended on CXCL12. We analyzed gene expression profiles using RNA from baseline and on treatment tumor samples of 14 melanoma patients. We identified baseline CXCL12 gene expression as possibly improving the likelihood or response to anti–CTLA-4 therapies. Our results provide a proof-of-principle demonstration that LFA-1 activation could convert a T cell–exclusionary TME to a T cell–enriched TME through mechanisms involving cooperation with innate immune cells.