Macrophages and cathepsin proteases blunt chemotherapeutic response in breast cancer

Cathepsins: Emerging targets in the tumor ecosystem to overcome cancers

Cathepsins, a group of lysosomal peptidases, have traditionally been recognized as tumor facilitators. Recent research, however, highlights their critical role in orchestrating cancer and the tumor microenvironment (TME). Primality, cathepsins degrade extracellular matrix, enabling cancer cells to invade and metastasize, while also promoting vascular endothelial infiltration and subsequent angiogenesis. Additionally, cathepsins boost fibroblast growth, thereby supporting tumor progression. More importantly, cathepsins are pivotal in modulating immune cells within the TME by regulating their recruitment, antigen processing and presentation, differentiation, and cell death, primarily contributing to immune suppression. Given their overexpression in tumors and elevated levels in the circulation of cancer patients, it is crucial to consider the systemic effects of cathepsins. Although the comprehensive role of cathepsins in cancer patients' bodies remains underexplored, they likely influence systemic immunity and inflammation, cellular metabolism, muscle wasting, and distant metastasis through their unique proteolytic functions. Notably, cathepsins also confer resistance to chemoradiotherapy by rewriting the cellular profile within the TME. In this context, promising results are emerging from studies combining cathepsin inhibitors with conventional therapies to suppress tumor development effectively. This review aims to decipher the cathepsin-driven networks within cancer cells and the TME, detailing their contribution to chemoradioresistance by reshaping both micro- and macroenvironments. Furthermore, we explore current and future perspectives on therapies targeting cathepsins' interactions, offering insights into innovative treatment strategies.

HOXC6 promotes the metastasis of MSI-H CRC by interacting with M2 macrophages and inducing effector T cell exhaustion

We previously discovered that HOXC6 was the most significantly upregulated gene in right-sided colon cancer compared to left-sided colon cancer according to our previous study; however, the role of HOXC6 in microsatellite instability-high (MSI-H) tumors remains poorly understood. Here, multiple public datasets, and in-house cohorts were used to analyze the differential expression and prognostic role of HOXC6 in colorectal cancer (CRC). Immunohistochemistry and immunofluorescence were performed to evaluate the correlation between HOXC6 expression and M2 macrophage infiltration. CCK8 and Transwell assays were used to evaluate the proliferation and migration of tumor cells in vitro. BALB/c nude mice were utilized to construct a humanized immune system model to evaluate the efficacy of ruxolitinib in vivo. We found that HOXC6 was overexpressed in MSI-H CRC and associated with a poor prognosis. Upregulation of CCL2 by HOXC6 increased M2 macrophage infiltration. IL6 secreted by M2 macrophages induced the epithelial-mesenchymal transition of tumor cells by upregulating HOXC6. M2 macrophages promoted effector T cell exhaustion by downregulating 4-1BB. Thus, inhibition of the IL6/JAK pathway in M2 macrophages restored 4-1BB expression and T-cell cytotoxicity offering a promising therapeutic target for the treatment of HOXC6-overexpressing MSI-H CRC.

Blood TCTP as a potential biomarker associated with immunosuppressive features and poor clinical outcomes in metastatic gastric cancer

BACKGROUND

No established biomarker exists for specific myeloid cell populations or in gastric cancer. This study aimed to explore the prognostic and immunological relevance of plasma translationally controlled tumor protein (TCTP) in patients with advanced gastric cancer treated with an immune checkpoint inhibitor and/or cytotoxic chemotherapy.

METHODS

Plasma samples were prospectively collected from the cohorts of patients with gastric cancer treated with first-line fluoropyrimidine plus platinum chemotherapy (n=143, cohort 1) and third-line nivolumab (n=165, cohort 2). Plasma TCTP levels were quantified using ELISA, and multiplex proteomic analysis (Olink) was conducted to assess expression levels of immune-related proteins. External single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics datasets were employed to validate the findings.

RESULTS

Patients with high plasma TCTP levels (TCTP-high group) exhibited poor progression-free survival (PFS) and overall survival (OS) with first-line chemotherapy compared with those with low levels (TCTP-low group) in cohort 1 (HR: 1.73 for PFS; 1.77 for OS). In the TCTP-high group, proteins associated with immunosuppressive myeloid cells, angiogenesis, and immune exclusion of T/natural killer (NK) cell function were upregulated, whereas proteins involved in T-cell activation/exhaustion were significantly upregulated in the TCTP-low group. scRNA-seq analyses identified a myeloid subset with high TPT1 (encoding TCTP) expression and TCTP-related molecules, enriched with inhibitory myeloid inflammation gene signatures and providing inhibitory signals to T/NK cells (Macrophage-chemokine). Spatial transcriptomics analyses revealed a tumor-cell-enriched cluster co-localized with the Macrophage-chemokine subset, which exhibited the highest TPT1 expression and a positive correlation between its abundance and average TPT1 levels. In nivolumab-treated patients (cohort 2), the high TCTP group was associated with poor survival outcomes (HR: 1.39 for PFS; 1.47 for OS).

CONCLUSIONS

Plasma TCTP is a prognostic biomarker, reflecting clinically relevant immunosuppressive myeloid signals in patients with gastric cancer.

Inflammation in cancer: therapeutic opportunities from new insights

As one part of the innate immune response to external stimuli, chronic inflammation increases the risk of various cancers, and tumor-promoting inflammation is considered one of the enabling characteristics of cancer development. Recently, there has been growing evidence on the role of anti-inflammation therapy in cancer prevention and treatment. And researchers have already achieved several noteworthy outcomes. In the review, we explored the underlying mechanisms by which inflammation affects the occurrence and development of cancer. The pro- or anti-tumor effects of these inflammatory factors such as interleukin, interferon, chemokine, inflammasome, and extracellular matrix are discussed. Since FDA-approved anti-inflammation drugs like aspirin show obvious anti-tumor effects, these drugs have unique advantages due to their relatively fewer side effects with long-term use compared to chemotherapy drugs. The characteristics make them promising candidates for cancer chemoprevention. Overall, this review discusses the role of these inflammatory molecules in carcinogenesis of cancer and new inflammation molecules-directed therapeutic opportunities, ranging from cytokine inhibitors/agonists, inflammasome inhibitors, some inhibitors that have already been or are expected to be applied in clinical practice, as well as recent discoveries of the anti-tumor effect of non-steroidal anti-inflammatory drugs and steroidal anti-inflammatory drugs. The advantages and disadvantages of their application in cancer chemoprevention are also discussed.

Vimentin intermediate filaments coordinate actin stress fibers and podosomes to determine the extracellular matrix degradation by macrophages

Macrophages possess the capacity to degrade extracellular matrix (ECM), but the specific roles of different cytoskeletal structures in controlling this process are incompletely understood. Here, we report that the inward flow of actin stress fibers delivers endocytosed ECM for lysosomal elimination, replenishing the pool of enzymes for extracellular ECM hydrolysis in actin-rich podosomes. Vimentin deficiency disrupted the balance between stress fibers and podosomes, impairing ECM degradation through integrin CD11b in THP-1 macrophages. In lung adenocarcinoma patient samples, M2-type macrophages exhibit a tighter podosome organization, surrounded by compact vimentin filaments, than M1-type. In vitro experiments verified that the invasion ability of A549 lung carcinoma cells was enhanced when accompanied by wild type, but not vimentin knockout M2-type THP-1, macrophages. Subcutaneous injections of macrophages and tumor cells in nude mice showed that vimentin in macrophages can reduce tumor collagen fibers. Together, our findings provide insights into the cytoskeletal dynamics governing macrophage ECM degradation.

Harnessing the tumor microenvironment: targeted cancer therapies through modulation of epithelial-mesenchymal transition

The tumor microenvironment (TME) is integral to cancer progression, impacting metastasis and treatment response. It consists of diverse cell types, extracellular matrix components, and signaling molecules that interact to promote tumor growth and therapeutic resistance. Elucidating the intricate interactions between cancer cells and the TME is crucial in understanding cancer progression and therapeutic challenges. A critical process induced by TME signaling is the epithelial-mesenchymal transition (EMT), wherein epithelial cells acquire mesenchymal traits, which enhance their motility and invasiveness and promote metastasis and cancer progression. By targeting various components of the TME, novel investigational strategies aim to disrupt the TME's contribution to the EMT, thereby improving treatment efficacy, addressing therapeutic resistance, and offering a nuanced approach to cancer therapy. This review scrutinizes the key players in the TME and the TME's contribution to the EMT, emphasizing avenues to therapeutically disrupt the interactions between the various TME components. Moreover, the article discusses the TME's implications for resistance mechanisms and highlights the current therapeutic strategies toward TME modulation along with potential caveats.

Direct visualization of emergent metastatic features within an ex vivo model of the tumor microenvironment

Ischemic conditions such as hypoxia and nutrient starvation, together with interactions with stromal cells, are critical drivers of metastasis. These conditions arise deep within tumor tissues, and thus, observing nascent metastases is exceedingly challenging. We thus developed the 3MIC-an ex vivo model of the tumor microenvironment-to study the emergence of metastatic features in tumor cells in a 3-dimensional (3D) context. Here, tumor cells spontaneously create ischemic-like conditions, allowing us to study how tumor spheroids migrate, invade, and interact with stromal cells under different metabolic conditions. Consistent with previous data, we show that ischemia increases cell migration and invasion, but the 3MIC allowed us to directly observe and perturb cells while they acquire these pro-metastatic features. Interestingly, our results indicate that medium acidification is one of the strongest pro-metastatic cues and also illustrate using the 3MIC to test anti-metastatic drugs on cells experiencing different metabolic conditions. Overall, the 3MIC can help dissecting the complexity of the tumor microenvironment for the direct observation and perturbation of tumor cells during the early metastatic process.

Macrophage-derived cathepsin L promotes epithelial-mesenchymal transition and M2 polarization in gastric cancer

BACKGROUND

Advanced gastric tumors are extremely prone to metastasize the in 20%-30% of gastric cancer, and patients have a poor prognosis despite systemic chemotherapy. Peritoneal metastases from gastric cancer usually indicate the end stage of the disease without curative treatment.

AIM

To peritoneal metastasis for facilitating clinical therapy are urgently needed.

METHODS

Immunohistochemical staining and immunofluorescence staining were used to demonstrate the high expression of cathepsin L (CTSL) in human gastric cancer tissues and its localization in cells. Lentivirus transfection was used to construct stable cell lines. Transwell invasion assays, wound healing assays, and animal tests were used to determine the relationships between CTSL and epithelial-mesenchymal transition (EMT) and tumorigenic potential in vivo.

RESULTS

We observed that macrophage-derived CTSL promoted gastric cancer cell migration and metastasis via the EMT pathway in vitro and in vivo, which involved macrophage polarization. Our findings suggest that macrophages improve extracellular matrix remodeling and hence facilitate tumor metastasis. Ablation of CTSL in macrophages within the tumor microenvironment may improve tumor therapy and the prognosis of patients with gastric cancer peritoneal metastasis.

CONCLUSION

In consideration of our findings, tumor-associated macrophage-derived CTSL is an important factor that promotes the metastasis and invasion of gastric cancer cells, and the targeting of CTSL may potentially improve the prognosis of patients with gastric cancer with peritoneal metastasis.

The emerging role of circular RNAs in cisplatin resistance in ovarian cancer: From molecular mechanism to future potential

Ovarian cancer (OC) is the most common cause of death in female cancers. The prognosis of OC is very poor due to delayed diagnosis and identification of most patients in advanced stages, metastasis, recurrence, and resistance to chemotherapy. As chemotherapy with platinum-based drugs such as cisplatin (DDP) is the main treatment in most OC cases, resistance to DDP is an important obstacle to achieving satisfactory therapeutic efficacy. Consequently, knowing the different molecular mechanisms involved in resistance to DDP is necessary to achieve new therapeutic approaches. According to numerous recent studies, non-coding RNAs (ncRNAs) could regulate proliferation, differentiation, apoptosis, and chemoresistance in many cancers, including OC. Most of these ncRNAs are released by tumor cells into human fluid, allowing them to be used as tools for diagnosis. CircRNAs are ncRNA family members that have a role in the initiation, progression, and chemoresistance regulation of various cancers. In the current study, we investigated the roles of several circRNAs and their signaling pathways on OC progression and also on DDP resistance during chemotherapy.

Targeting of TAMs: can we be more clever than cancer cells?

АBSTRACT: With increasing incidence and geography, cancer is one of the leading causes of death, reduced quality of life and disability worldwide. Principal progress in the development of new anticancer therapies, in improving the efficiency of immunotherapeutic tools, and in the personification of conventional therapies needs to consider cancer-specific and patient-specific programming of innate immunity. Intratumoral TAMs and their precursors, resident macrophages and monocytes, are principal regulators of tumor progression and therapy resistance. Our review summarizes the accumulated evidence for the subpopulations of TAMs and their increasing number of biomarkers, indicating their predictive value for the clinical parameters of carcinogenesis and therapy resistance, with a focus on solid cancers of non-infectious etiology. We present the state-of-the-art knowledge about the tumor-supporting functions of TAMs at all stages of tumor progression and highlight biomarkers, recently identified by single-cell and spatial analytical methods, that discriminate between tumor-promoting and tumor-inhibiting TAMs, where both subtypes express a combination of prototype M1 and M2 genes. Our review focuses on novel mechanisms involved in the crosstalk among epigenetic, signaling, transcriptional and metabolic pathways in TAMs. Particular attention has been given to the recently identified link between cancer cell metabolism and the epigenetic programming of TAMs by histone lactylation, which can be responsible for the unlimited protumoral programming of TAMs. Finally, we explain how TAMs interfere with currently used anticancer therapeutics and summarize the most advanced data from clinical trials, which we divide into four categories: inhibition of TAM survival and differentiation, inhibition of monocyte/TAM recruitment into tumors, functional reprogramming of TAMs, and genetic enhancement of macrophages.

Research progress in the mechanisms and functions of specialized pro-resolving mediators in neurological diseases

The nervous system interacts with the immune system through a variety of cellular regulators, signaling pathways, and molecular mechanisms. Disruptions in these interactions lead to the development of multiple neurological diseases. Recent studies have identified that specialized pro-resolving mediators (SPMs) play a regulatory role in the neuroimmune system. This study reviews recent research on the function of SPMs in the inflammatory process and their association with the nervous system. The review aims to provide new perspectives for studying the pathogenesis of neurological diseases and identify novel targets for clinical therapy.

Tumor-associated macrophages confer resistance to chemotherapy (Trifluridine/Tipiracil) in digestive cancers by overexpressing thymidine phosphorylase

Pyrimidine analogs are part of the first-line chemotherapy regimen for gastrointestinal cancers. Trifluridine combined with tipiracil, a specific thymidine phosphorylase inhibitor, in TAS-102 has recently emerged as a potential alternative in the face of primary or secondary chemoresistance to 5-fluorouracil. Despite its promise, we report that macrophage-specific overexpression of thymidine phosphorylase results in macrophage-induced chemoresistance to TAS-102 that is insensitive to tipiracil inhibition. Furthermore, we illustrate the human-specific nature of this mechanism, as mouse macrophages do not express substantial levels of thymidine phosphorylase, which constrains the applicability of mouse models. To study the importance of macrophages in chemoresistance to trifluridine, we developed a humanized mouse model with tumor-implanted human macrophages and demonstrated their important role in treatment resistance to pyrimidine analogs. Additionally, our findings revealed that macrophages represent a significant source of thymidine phosphorylase expression, comprising over 40 % of the expressing cells, in human colorectal cancer, thereby contributing to chemoresistance.

Roles of cathepsin S expression levels on the prognosis and tumour microenvironment in clear cell renal cell carcinoma

BACKGROUND

Increasing evidence suggests a link between the enzyme cathepsin S (CTSS) and tumour development. However, the potential involvement and molecular functions of CTSS in clear cell renal cell carcinoma (ccRCC) remain unclear.

METHODS

We downloaded original data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases and integrated them using R. Kaplan-Meier plots of integrated expression scores were used to analyse survival outcomes. Additionally, we investigated mRNA expression, clinicopathological features, immune infiltrates, and single-cell sequencing analysis of CTSS in ccRCC. In vitro experiments were conducted with qRT-PCR and IHC staining.

RESULTS

CTSS transcriptomic and proteomic levels were higher in ccRCC than in para-cancerous tissues. Low CTSS expression was correlated with poor prognosis in patients with ccRCC. Our data demonstrated that the expression of CTSS was strongly correlated with immune cell infiltration levels and gene markers of immune cells, chemokines, and receptors. Single-cell sequencing analysis demonstrated that CTSS expression was detectable in monocytes/macrophages. Finally, certain chemicals were confirmed to affect CTSS expression.

CONCLUSION

Our findings indicate that CTSS offers promise as a prognostic biomarker and novel immune-related therapeutic target for ccRCC.

Single-cell data revealed the function of natural killer cells and macrophage cells in chemotherapy tolerance in acute myeloid leukemia

Background

Acute myeloid leukemia (AML) is highly prevalent and heterogeneous among adult acute leukemias. Current chemotherapeutic approaches for AML often face the challenge of drug resistance, and AML immune cells play an important role in the regulation of AML drug resistance. Thus, it is of key significance to explore the regulatory mechanisms of immune cells in AML to alleviate chemotherapy resistance in AML.

Methods

Based on AML single-cell transcriptomic data, this study revealed the differences in the expression of immune cell subpopulations and marker genes in AML patients in the complete remission group (CR) compared to AML patients in the non-complete remission group (non-CR) after chemotherapy. Functional enrichment by clusterprofiler revealed the regulatory functions of differentially expressed genes (DEGs) in AML. AUCell enrichment scores were used to assess the immunoregulatory functions of immune cells. Pseudotime analysis was used to construct immune cell differentiation trajectories. CellChat was used for cellular communication analysis to elucidate the interactions between immune cells. Survival analysis with the R package "survival" revealed the role of immune cell marker genes on AML prognosis. Finally, the wound healing and trans-well assay were performed.

Results

Single-cell clustering analysis revealed that NK/T cells and macrophage cells subpopulations were significantly higher in non-CR AML patients than in CR AML. AUCell enrichment analysis revealed that FCAR+ and FCGR3A+ macrophages were significantly more active in the non-CR group and correlated with processes regulating cellular energy metabolism and immune cell activity. Differentially expressed NK cell marker genes between CR and non-CR groups mainly included HBA1, S100A8, and S100A9, which were associated with cancer drug resistance regulation, these marker genes of (FCAR, FCGR3A, PREX1, S100A8 and S100A9) were upregulated in human chronic myeloid leukemia cells (HAP1) and silencing of S100A8 affected migration and invasion of HAP1 cells. In particular, the differentiation pathways of macrophages and NK cells in non-CR differed from those of patients in the CR group. Cellular communication analyses showed that ligand-receptor pairs between NK cells and macrophage cells mainly included HLA-E-KLRK1, HLA-E-KLRC1, HLA-E-CD94:NKG2A, CLEC2B-KLRB1. In addition, LGALS9-CD45, CCL3L1- CCR1, CCL3-CCR1 between these two immune cells mainly regulate secreted signaling to mediate AML progression. Marker genes in NK/T cells and macrophage cells were significantly associated with AML prognosis.

Conclusion

This study reveals the potential role of NK cells and macrophages in AML chemoresistance through the analysis of single-cell RNA sequencing data. This provides new ideas and insights into the key mechanisms of immune cells in AML treatment.

The role of macrophage migratory behavior in development, homeostasis and tumor invasion

Tumor-associated macrophages (TAMs) recapitulate the developmental and homeostatic behaviors of tissue resident macrophages (TRMs) to promote tumor growth, invasion and metastasis. TRMs arise in the embryo and colonize developing tissues, initially to guide tissue morphogenesis and then to form complex networks in adult tissues to constantly search for threats to homeostasis. The macrophage growth factor, colony-stimulating factor-1 (CSF-1), which is essential for TRM survival and differentiation, is also responsible for the development of the unique motility machinery of mature macrophages that underpins their ramified morphologies, migratory capacity and ability to degrade matrix. Two CSF-1-activated kinases, hematopoietic cell kinase and the p110δ catalytic isoform of phosphatidylinositol 3-kinase, regulate this machinery and selective inhibitors of these proteins completely block macrophage invasion. Considering tumors co-opt the invasive capacity of TAMs to promote their own invasion, these proteins are attractive targets for drug development to inhibit tumor progression to invasion and metastasis.

LncRNA ZNF649-AS1 promotes trastuzumab resistance and TAM-dependent PD-L1 expression in breast cancer by regulating EXOC7 alternative splicing

BACKGROUND

Trastuzumab resistance is a serious clinical problem in the treatment of HER2-positive breast cancer (BC). The lncRNA ZNF649-AS1 was previously found to promote HER2-positive BC trastuzumab resistance. The study aims to explore the molecular mechanism of ZNF649-AS1 in HER2-positive BC trastuzumab resistance.

METHODS

Tumor tissue and peripheral blood samples were collected from 20 HER2-positive BC patients with trastuzumab-resistant and non-resistant, respectively. Trastuzumab-resistant BC cell lines SKBR-3-TR and BT474-TR were established. RIP was employed to confirm the binding of ZNF649-AS1, PRPF8 and exocyst complex component 7 (EXOC7). RNA expression of EXOC7-L (Full length of EXOC7) and EXOC7-S (Spliceosome of EXOC7) were detected using agarose gel electrophoresis. Expressions of macrophage markers CD68+ CD206+ were measured by flow cytometry.

RESULTS

ZNF649-AS1 expression was upregulated in HER2-positive BC trastuzumab resistance. ZNF649-AS1 downregulation inhibited trastuzumab resistance in HER2-positive BC. ZNF649-AS1 regulated EXOC7 alternative splicing by binding with PRPF8. EXOC7-S knockdown suppressed trastuzumab resistance and TAM-dependent PD-L1 expression in HER2-positive BC. EXOC7-S overexpression abolished the effects of ZNF649-AS1 knockdown on trastuzumab resistance and TAM-dependent PD-L1 expression in HER2-positive BC.

CONCLUSION

ZNF649-AS1 promoted trastuzumab resistance and TAM-dependent PD-L1 expression in HER2-positive BC via promoting alternative splicing of EXOC7 by PRPF8.

Cysteine cathepsins: From diagnosis to targeted therapy of cancer

Cysteine cathepsins are a fascinating group of proteolytic enzymes that play diverse and crucial roles in numerous biological processes, both in health and disease. Understanding these proteases is essential for uncovering novel insights into the underlying mechanisms of a wide range of disorders, such as cancer. Cysteine cathepsins influence cancer biology by participating in processes such as extracellular matrix degradation, angiogenesis, immune evasion, and apoptosis. In this comprehensive review, we explore foundational research that illuminates the diverse and intricate roles of cysteine cathepsins as diagnostic markers and therapeutic targets for cancer. This review aims to provide valuable insights into the clinical relevance of cysteine cathepsins and explore their capacity to advance personalised and targeted medical interventions in oncology.

Bidirectional activation of stem-like programs between metastatic cancer and alveolar type 2 cells within the niche

A key step for metastatic outgrowth involves the generation of a deeply altered microenvironment (niche) that supports the malignant behavior of cancer cells. The complexity of the metastatic niche has posed a significant challenge in elucidating the underlying programs driving its origin. Here, by focusing on early stages of breast cancer metastasis to the lung in mice, we describe a cancer-dependent chromatin remodeling and activation of developmental programs in alveolar type 2 (AT2) cells within the niche. We show that metastatic cells can prime AT2 cells into a reprogrammed multilineage state. In turn, this cancer-induced reprogramming of AT2 cells promoted stem-like features in cancer cells and enhanced their initiation capacity. In conclusion, we propose the concept of "reflected stemness" as an early phenomenon during metastatic niche initiation, wherein metastatic cells reprogram the local tissue into a stem-like state that enhances intrinsic cancer-initiating potential, creating a positive feedback loop where tumorigenic programs are amplified.

The CXCR2 chemokine receptor: A new target for gastric cancer therapy

Gastric cancer (GC) is one of the most common malignant tumors in the world, and current treatments are still based on surgery and drug therapy. However, due to the complexity of immunosuppression and drug resistance, the treatment of gastric cancer still faces great challenges. Chemokine receptor 2 (CXCR2) is one of the most common therapeutic targets in targeted therapy. As a G protein-coupled receptor, CXCR2 and its ligands play important roles in tumorigenesis and progression. The abnormal expression of these genes in cancer plays a decisive role in the recruitment and activation of white blood cells, angiogenesis, and cancer cell proliferation, and CXCR2 is involved in various stages of tumor development. Therefore, interfering with the interaction between CXCR2 and its ligands is considered a possible target for the treatment of various tumors, including gastric cancer.

The role of host response to chemotherapy: resistance, metastasis and clinical implications

Chemotherapy remains the primary treatment for most metastatic cancers. However, the response to chemotherapy and targeted agents is often transient, and concurrent development of resistance is the primary impediment to effective cancer therapy. Strategies to overcome resistance to treatment have focused on cancer cell intrinsic factors and the tumor microenvironment (TME). Recent evidence indicates that systemic chemotherapy has a significant impact on the host that either facilitates tumor growth, allowing metastatic spread, or renders treatment ineffective. These host responses include the release of bone marrow-derived cells, activation of stromal cells in the TME, and induction of different molecular effectors. Here, we provide an overview of chemotherapy-induced systemic host responses that support tumor aggressiveness and metastasis, and which contribute to therapy resistance. Studying host responses to chemotherapy provides a solid basis for the development of adjuvant strategies to improve treatment outcomes and delay resistance to chemotherapy. This review discusses the emerging field of host response to cancer therapy, and its preclinical and potential clinical implications, explaining how under certain circumstances, these host effects contribute to metastasis and resistance to chemotherapy.

A review concerning the breast cancer-related tumour microenvironment

Breast cancer (BC) is currently the most common malignant tumour in women and one of the leading causes of their death around the world. New and increasingly personalised diagnostic and therapeutic tools have been introduced over the last few decades, along with significant advances regarding the study and knowledge related to BC. The tumour microenvironment (TME) refers to the tumour cell-associated cellular and molecular environment which can influence conditions affecting tumour development and progression. The TME is composed of immune cells, stromal cells, extracellular matrix (ECM) and signalling molecules secreted by these different cell types. Ever deeper understanding of TME composition changes during tumour development and progression will enable new and more innovative therapeutic strategies to become developed for targeting tumours during specific stages of its evolution. This review summarises the role of BC-related TME components and their influence on tumour progression and the development of resistance to therapy. In addition, an account on the modifications in BC-related TME components associated with therapy is given, and the completed or ongoing clinical trials related to this topic are presented.

Neutrophil extracellular traps modulate chemotherapy efficacy and its adverse side effects

Neutrophils, major regulator of innate immunity have recently emerged as key components of the tumor microenvironment. The role of neutrophils in cancer has been linked to their ability to form neutrophil extracellular traps (NETs), structures composed of decondensed DNA decorated with enzymes that are released into the extracellular space. Here, we discuss the pivotal roles of NETs, in influencing responses to chemotherapy and its severe adverse effect. Highlighting recent insights, we discuss the dual nature of NETs in the context of chemotherapy treatment, examining their potential to either counteract or enhance treatment outcomes. Strategic targeting of NETs emerges as a promising avenue for determining combination therapies that could help counteracting resistance or enhancing chemotherapy efficacy as well as limiting complications due to this type of treatment.

COL5A1 promotes triple-negative breast cancer progression by activating tumor cell-macrophage crosstalk

Triple-negative breast cancer (TNBC) is an exceptionally aggressive subtype of breast cancer. Despite the recognized interplay between tumors and tumor-associated macrophages in fostering drug resistance and disease progression, the precise mechanisms leading these interactions remain elusive. Our study revealed that the upregulation of collagen type V alpha 1 (COL5A1) in TNBC tissues, particularly in chemoresistant samples, was closely linked to an unfavorable prognosis. Functional assays unequivocally demonstrated that COL5A1 played a pivotal role in fueling cancer growth, metastasis, and resistance to doxorubicin, both in vitro and in vivo. Furthermore, we found that the cytokine IL-6, produced by COL5A1-overexpressing TNBC cells actively promoted M2 macrophage polarization. In turn, TGFβ from M2 macrophages drived TNBC doxorubicin resistance through the TGFβ/Smad3/COL5A1 signaling pathway, establishing a feedback loop between TNBC cells and macrophages. Mechanistically, COL5A1 interacted with TGM2, inhibiting its K48-linked ubiquitination-mediated degradation, thereby enhancing chemoresistance and increasing IL-6 secretion. In summary, our findings underscored the significant contribution of COL5A1 upregulation to TNBC progression and chemoresistance, highlighting its potential as a diagnostic and therapeutic biomarker for TNBC.

Targeting the innate immune system in pediatric and adult AML

While the introduction of T cell-based immunotherapies has improved outcomes in many cancer types, the development of immunotherapies for both adult and pediatric AML has been relatively slow and limited. In addition to the need to identify suitable target antigens, a better understanding of the immunosuppressive tumor microenvironment is necessary for the design of novel immunotherapy approaches. To date, most immune characterization studies in AML have focused on T cells, while innate immune lineages such as monocytes, granulocytes and natural killer (NK) cells, received less attention. In solid cancers, studies have shown that innate immune cells, such as macrophages, myeloid-derived suppressor cells and neutrophils are highly plastic and may differentiate into immunosuppressive cells depending on signals received in their microenvironment, while NK cells appear to be functionally impaired. Hence, an in-depth characterization of the innate immune compartment in the TME is urgently needed to guide the development of immunotherapeutic interventions for AML. In this review, we summarize the current knowledge on the innate immune compartment in AML, and we discuss how targeting its components may enhance T cell-based- and other immunotherapeutic approaches.

Macrophages and tumor-associated macrophages in the senescent microenvironment: From immunosuppressive TME to targeted tumor therapy

In-depth studies of the tumor microenvironment (TME) have helped to elucidate its cancer-promoting mechanisms and inherent characteristics. Cellular senescence, which acts as a response to injury and can the release of senescence-associated secretory phenotypes (SASPs). These SASPs release various cytokines, chemokines, and growth factors, remodeling the TME. This continual development of a senescent environment could be associated with chronic inflammation and immunosuppressive TME. Additionally, SASPs could influence the phenotype and function of macrophages, leading to the recruitment of tumor-associated macrophages (TAMs). This contributes to tumor proliferation and metastasis in the senescent microenvironment, working in tandem with immune regulation, angiogenesis, and therapeutic resistance. This comprehensive review covers the evolving nature of the senescent microenvironment, macrophages, and TAMs in tumor development. We also explored the links between chronic inflammation, immunosuppressive TME, cellular senescence, and macrophages. Moreover, we compiled various tumor-specific treatment strategies centered on cellular senescence and the current challenges in cellular senescence research. This study aimed to clarify the mechanism of macrophages and the senescent microenvironment in tumor progression and advance the development of targeted tumor therapies.

Ruthenium-Cathepsin Inhibitor Conjugates for Green Light-Activated Photodynamic Therapy and Photochemotherapy

Dysregulated cathepsin activity is linked to various human diseases including metabolic disorders, autoimmune conditions, and cancer. Given the overexpression of cathepsin in the tumor microenvironment, cathepsin inhibitors are promising pharmacological agents and drug delivery vehicles for cancer treatment. In this study, we describe the synthesis and photochemical and biological assessment of a dual-action agent based on ruthenium that is conjugated with a cathepsin inhibitor, designed for both photodynamic therapy (PDT) and photochemotherapy (PCT). The ruthenium-cathepsin inhibitor conjugate was synthesized through an oxime click reaction, combining a pan-cathepsin inhibitor based on E64d with the Ru(II) PCT/PDT fragment [Ru(dqpy)(dppn)], where dqpy = 2,6-di(quinoline-2-yl)pyridine and dppn = benzo[i]dipyrido[3,2-a:2',3'-c]phenazine. Photochemical investigations validated the conjugate's ability to release a triazole-containing cathepsin inhibitor for PCT and to generate singlet oxygen for PDT upon exposure to green light. Inhibition studies demonstrated the conjugate's potent and irreversible inactivation of purified and intracellular cysteine cathepsins. Two Ru(II) PCT/PDT agents based on the [Ru(dqpy)(dppn)] moiety were evaluated for photoinduced cytotoxicity in 4T1 murine triple-negative breast cancer cells, L929 fibroblasts, and M0, M1, and M2 macrophages. The cathepsin inhibitor conjugate displayed notable selectivity for inducing cell death under irradiation compared to dark conditions, mitigating toxicity in the dark observed with the triazole control complex [Ru(dqpy)(dppn)(MeTz)]2+ (MeTz = 1-methyl-1H-1,2,4-triazole). Notably, our lead complex is among a limited number of dual PCT/PDT agents activated with green light.

Respiratory complex I regulates dendritic cell maturation in explant model of human tumor immune microenvironment

BACKGROUND

Combining cytotoxic chemotherapy or novel anticancer drugs with T-cell modulators holds great promise in treating advanced cancers. However, the response varies depending on the tumor immune microenvironment (TIME). Therefore, there is a clear need for pharmacologically tractable models of the TIME to dissect its influence on mono- and combination treatment response at the individual level.

METHODS

Here we establish a patient-derived explant culture (PDEC) model of breast cancer, which retains the immune contexture of the primary tumor, recapitulating cytokine profiles and CD8+T cell cytotoxic activity.

RESULTS

We explored the immunomodulatory action of a synthetic lethal BCL2 inhibitor venetoclax+metformin drug combination ex vivo, discovering metformin cannot overcome the lymphocyte-depleting action of venetoclax. Instead, metformin promotes dendritic cell maturation through inhibition of mitochondrial complex I, increasing their capacity to co-stimulate CD4+T cells and thus facilitating antitumor immunity.

CONCLUSIONS

Our results establish PDECs as a feasible model to identify immunomodulatory functions of anticancer drugs in the context of patient-specific TIME.

Pharmacological approaches for targeting lysosomes to induce ferroptotic cell death in cancer

Lysosomes are crucial organelles responsible for the degradation of cytosolic materials and bulky organelles, thereby facilitating nutrient recycling and cell survival. However, lysosome also acts as an executioner of cell death, including ferroptosis, a distinctive form of regulated cell death that hinges on iron-dependent phospholipid peroxidation. The initiation of ferroptosis necessitates three key components: substrates (membrane phospholipids enriched with polyunsaturated fatty acids), triggers (redox-active irons), and compromised defence mechanisms (GPX4-dependent and -independent antioxidant systems). Notably, iron assumes a pivotal role in ferroptotic cell death, particularly in the context of cancer, where iron and oncogenic signaling pathways reciprocally reinforce each other. Given the lysosomes' central role in iron metabolism, various strategies have been devised to harness lysosome-mediated iron metabolism to induce ferroptosis. These include the re-mobilization of iron from intracellular storage sites such as ferritin complex and mitochondria through ferritinophagy and mitophagy, respectively. Additionally, transcriptional regulation of lysosomal and autophagy genes by TFEB enhances lysosomal function. Moreover, the induction of lysosomal iron overload can lead to lysosomal membrane permeabilization and subsequent cell death. Extensive screening and individually studies have explored pharmacological interventions using clinically available drugs and phytochemical agents. Furthermore, a drug delivery system involving ferritin-coated nanoparticles has been specifically tailored to target cancer cells overexpressing TFRC. With the rapid advancements in understandings the mechanistic underpinnings of ferroptosis and iron metabolism, it is increasingly evident that lysosomes represent a promising target for inducing ferroptosis and combating cancer.

PGRN inhibits CD8+T cell recruitment and promotes breast cancer progression by up-regulating ICAM-1 on TAM

BACKGROUND

Tumor microenvironment actually reduces antitumor effect against the immune attack by exclusion of CD8+T cells. Progranulin (PGRN) is a multifunctional growth factor with significant pathological effects in multiple tumors; however, its role in immunity evasion of breast cancer (BCa) is not completely understood.

METHODS

We depleted GRN (PGRN gene) genetically in mice or specifically in PY8119 murine BCa cell line, and mouse models of orthotopic or subcutaneous transplantation were used. Chimeric mice-deficient of PGRN (Grn-/-) in bone marrow (BM) compartment was also generated. Association of PGRN expression with chemokine production or BCa development was investigated by histological and immunological assays.

RESULTS

We found PGRN was involved in exhaustion of cytotoxic CD8+T cell in BCa with the increasing expressions of M2 markers and intercellular cell adhesion molecule-1 (ICAM-1) on macrophages. Specifically, ablation of PGRN in PY8119 cells reduced tumor burden, accompanied by the infiltrating of cytotoxic CD8+T cells into tumor nests. Moreover, our result revealed that blockade of PD-1 in PGRN-depleted tumors exhibited better antitumor effect in vivo and significantly decreased tumor burden.

CONCLUSION

These findings suggest that inhibition of PGRN may act as a potential immune-therapeutic strategy by recovering infiltration of CD8+T cell in BCa tissue and thereby enhancing the response to anti-PD-1 therapy.

Cellular interactions in tumor microenvironment during breast cancer progression: new frontiers and implications for novel therapeutics

The breast cancer tumor microenvironment (TME) is dynamic, with various immune and non-immune cells interacting to regulate tumor progression and anti-tumor immunity. It is now evident that the cells within the TME significantly contribute to breast cancer progression and resistance to various conventional and newly developed anti-tumor therapies. Both immune and non-immune cells in the TME play critical roles in tumor onset, uncontrolled proliferation, metastasis, immune evasion, and resistance to anti-tumor therapies. Consequently, molecular and cellular components of breast TME have emerged as promising therapeutic targets for developing novel treatments. The breast TME primarily comprises cancer cells, stromal cells, vasculature, and infiltrating immune cells. Currently, numerous clinical trials targeting specific TME components of breast cancer are underway. However, the complexity of the TME and its impact on the evasion of anti-tumor immunity necessitate further research to develop novel and improved breast cancer therapies. The multifaceted nature of breast TME cells arises from their phenotypic and functional plasticity, which endows them with both pro and anti-tumor roles during tumor progression. In this review, we discuss current understanding and recent advances in the pro and anti-tumoral functions of TME cells and their implications for developing safe and effective therapies to control breast cancer progress.

Made to order: emergency myelopoiesis and demand-adapted innate immune cell production

Definitive haematopoiesis is the process by which haematopoietic stem cells, located in the bone marrow, generate all haematopoietic cell lineages in healthy adults. Although highly regulated to maintain a stable output of blood cells in health, the haematopoietic system is capable of extensive remodelling in response to external challenges, prioritizing the production of certain cell types at the expense of others. In this Review, we consider how acute insults, such as infections and cytotoxic drug-induced myeloablation, cause molecular, cellular and metabolic changes in haematopoietic stem and progenitor cells at multiple levels of the haematopoietic hierarchy to drive accelerated production of the mature myeloid cells needed to resolve the initiating insult. Moreover, we discuss how dysregulation or subversion of these emergency myelopoiesis mechanisms contributes to the progression of chronic inflammatory diseases and cancer.

Macrophage: Hidden Criminal in Therapy Resistance

BACKGROUND

Although substantial efforts have been made by researchers to develop drugs, a disappointing reality is that the emergence of drug resistance is an unavoidable reality for the majority of patients. In recent years, emerging evidence suggests a connection between drug resistance and immune dysregulation.

SUMMARY

As a ubiquitously distributed, versatile innate immune cell, macrophages play essential roles in maintaining tissue homeostasis in a steady state. Nevertheless, it is becoming aware that macrophages undermine the action of therapeutic drugs across various disease types. Reprogramming macrophage function has been proven to be effective in restoring patient responsiveness to treatment. Herein, we comprehensively reviewed how macrophages respond to drugs and the mechanisms by which they contribute to treatment unresponsiveness in cancer, inflammatory diseases, and metabolic diseases. In addition, future prospects in macrophage-based combination therapy were discussed.

KEY MESSAGES

Targeting macrophages is a promising strategy for overcoming drug resistance in immune disorders.

The cellular composition of the tumor microenvironment is an important marker for predicting therapeutic efficacy in breast cancer

At present, the incidence rate of breast cancer ranks first among new-onset malignant tumors in women. The tumor microenvironment is a hot topic in tumor research. There are abundant cells in the tumor microenvironment that play a protumor or antitumor role in breast cancer. During the treatment of breast cancer, different cells have different influences on the therapeutic response. And after treatment, the cellular composition in the tumor microenvironment will change too. In this review, we summarize the interactions between different cell compositions (such as immune cells, fibroblasts, endothelial cells, and adipocytes) in the tumor microenvironment and the treatment mechanism of breast cancer. We believe that detecting the cellular composition of the tumor microenvironment is able to predict the therapeutic efficacy of treatments for breast cancer and benefit to combination administration of breast cancer.

Defining and targeting macrophage heterogeneity in the mammary gland and breast cancer

INTRODUCTION

Macrophages are innate immune cells that are associated with extensive phenotypic and functional plasticity and contribute to normal development, tissue homeostasis, and diseases such as cancer. In this review, we discuss the heterogeneity of tissue resident macrophages in the normal mammary gland and tumor-associated macrophages in breast cancer. Tissue resident macrophages are required for mammary gland development, where they have been implicated in promoting extracellular matrix remodeling, apoptotic clearance, and cellular crosstalk. In the context of cancer, tumor-associated macrophages are key drivers of growth and metastasis via their ability to promote matrix remodeling, angiogenesis, lymphangiogenesis, and immunosuppression.

METHOD

We identified and summarized studies in Pubmed that describe the phenotypic and functional heterogeneity of macrophages and the implications of targeting individual subsets, specifically in the context of mammary gland development and breast cancer. We also identified and summarized recent studies using single-cell RNA sequencing to identify and describe macrophage subsets in human breast cancer samples.

RESULTS

Advances in single-cell RNA sequencing technologies have yielded nuances in macrophage heterogeneity, with numerous macrophage subsets identified in both the normal mammary gland and breast cancer tissue. Macrophage subsets contribute to mammary gland development and breast cancer progression in differing ways, and emerging studies highlight a role for spatial localization in modulating their phenotype and function.

CONCLUSION

Understanding macrophage heterogeneity and the unique functions of each subset in both normal mammary gland development and breast cancer progression may lead to more promising targets for the treatment of breast cancer.

Targeting circulating tumor cells to prevent metastases

Circulating tumor cells (CTCs) are cancer cells that detach from the primary tumor, enter the bloodstream or body fluids, and spread to other body parts, leading to metastasis. Their presence and characteristics have been linked to cancer progression and poor prognosis in different types of cancer. Analyzing CTCs can offer valuable information about tumors' genetic and molecular diversity, which is crucial for personalized therapy. Epithelial-mesenchymal transition (EMT) and the reverse process, mesenchymal-epithelial transition (MET), play a significant role in generating and disseminating CTCs. Certain proteins, such as EpCAM, vimentin, CD44, and TGM2, are vital in regulating EMT and MET and could be potential targets for therapies to prevent metastasis and serve as detection markers. Several devices, methods, and protocols have been developed for detecting CTCs with various applications. CTCs interact with different components of the tumor microenvironment. The interactions between CTCs and tumor-associated macrophages promote local inflammation and allow the cancer cells to evade the immune system, facilitating their attachment and invasion of distant metastatic sites. Consequently, targeting and eliminating CTCs hold promise in preventing metastasis and improving patient outcomes. Various approaches are being explored to reduce the volume of CTCs. By investigating and discussing targeted therapies, new insights can be gained into their potential effectiveness in inhibiting the spread of CTCs and thereby reducing metastasis. The development of such treatments offers great potential for enhancing patient outcomes and halting disease progression.

Targeting the Tumor Microenvironment in Breast Cancer: Prognostic and Predictive Significance and Therapeutic Opportunities

Breast cancer is one of the most prevalent tumors among women. Its prognosis and treatment outcomes depend on factors related to tumor cell biology. However, recent studies have revealed the critical role of the tumor microenvironment (TME) in the development, progression, and treatment response of breast cancer. In this review, we explore the different components of the TME and their relevance as prognostic and predictive biomarkers in breast cancer. In addition, techniques for assessing the tumor microenvironment, such as immunohistochemistry or gene expression profiling, and their clinical utility in therapeutic decision-making are examined. Finally, therapeutic strategies targeting the TME are reviewed, highlighting their potential clinical benefits. Overall, this review emphasizes the importance of the TME in breast cancer and its potential as a clinical tool for better patient stratification and the design of personalized therapies.

Good CARMA: Turning bad tumor-resident myeloid cells good with chimeric antigen receptor macrophages

In religious philosophy, the concept of karma represents the effect of one's past and present actions on one's future. Macrophages are highly plastic cells with myriad roles in health and disease. In the setting of cancer, macrophages are among the most plentiful members of the immune microenvironment where they generally support tumor growth and restrain antitumor immunity. However, macrophages are not necessarily born bad. Macrophages or their immediate progenitors, monocytes, are induced to traffic to the tumor microenvironment (TME) and during this process they are polarized toward a tumor-promoting phenotype. Efforts to deplete or repolarize tumor-associated macrophages (TAM) for therapeutic benefit in cancer have to date disappointed. By contrast, genetic engineering of macrophages followed by their transit into the TME may allow these impressionable cells to mend their ways. In this review, we summarize and discuss recent advances in the genetic engineering of macrophages for the treatment of cancer.

Identification of lncRNAs associated with T cells as potential biomarkers and therapeutic targets in lung adenocarcinoma

Lung adenocarcinoma (LUAD) is the most common and deadliest subtype of lung cancer. To select more targeted and effective treatments for individuals, further advances in classifying LUAD are urgently needed. The number, type, and function of T cells in the tumor microenvironment (TME) determine the progression and treatment response of LUAD. Long noncoding RNAs (lncRNAs), may regulate T cell differentiation, development, and activation. Thus, our aim was to identify T cell-related lncRNAs (T cell-Lncs) in LUAD and to investigate whether T cell-Lncs could serve as potential stratifiers and therapeutic targets. Seven T cell-Lncs were identified to further establish the T cell-related lncRNA risk score (TRS) in LUAD. Low TRS individuals were characterized by robust immune status, fewer genomic alterations, and remarkably longer survival than high TRS individuals. The excellent accuracy of TRS in predicting overall survival (OS) was validated in the TCGA-LUAD training cohort and the GEO-LUAD validation cohort. Our data demonstrated the favorable predictive power of the TRS-based nomogram, which had important clinical significance in estimating the survival probability for individuals. In addition, individuals with low TRS could respond better to chemotherapy and immunotherapy than those with high TRS. LINC00525 was identified as a valuable study target, and the ability of LUAD to proliferate or invade was significantly attenuated by downregulation of LINC00525. In conclusion, the TRS established by T cell-Lncs could unambiguously classify LUAD patients, predict their prognosis and guide their management. Moreover, our identified T cell-Lncs could provide potential therapeutic targets for LUAD.

Chemotherapy-induced metastasis: molecular mechanisms and clinical therapies

Chemotherapy, the most widely accepted treatment for malignant tumors, is dependent on cell death induced by various drugs including antimetabolites, alkylating agents, mitotic spindle inhibitors, antitumor antibiotics, and hormonal anticancer drugs. In addition to causing side effects due to non-selective cytotoxicity, chemotherapeutic drugs can initiate and promote metastasis, which greatly reduces their clinical efficacy. The knowledge of how they induce metastasis is essential for developing strategies that improve the outcomes of chemotherapy. Herein, we summarize the recent findings on chemotherapy-induced metastasis and discuss the underlying mechanisms including tumor-initiating cell expansion, the epithelial-mesenchymal transition, extracellular vesicle involvement, and tumor microenvironment alterations. In addition, the use of combination treatments to overcome chemotherapy-induced metastasis is also elaborated.

Function and clinical application of exosome-how to improve tumor immunotherapy?

In recent years, immunotherapy has been increasingly used in clinical practice to treat tumors. However, immunotherapy's efficacy varies between tumor types and patient populations, and long-term drug resistance often occurs during treatment. Therefore, it is essential to explore the molecular mechanisms of immunotherapy to improve its efficacy. In this review, we focus on the significance of tumor-derived exosomes in the clinical treatment of tumors and how modifying these exosomes may enhance immune effectiveness. Specifically, we discuss exosome components, such as RNA, lipids, and proteins, and the role of membrane molecules on exosome surfaces. Additionally, we highlight the importance of engineered exosomes for tumor immunotherapy. Our goal is to propose new strategies to improve the efficacy of tumor immunotherapy.

Vinblastine resets tumor-associated macrophages toward M1 phenotype and promotes antitumor immune response

BACKGROUND

Massive tumor-associated macrophage (TAM) infiltration is observed in many tumors, which usually display the immune-suppressive M2-like phenotype but can also be converted to an M1-like antitumor phenotype due to their high degree of plasticity. The macrophage polarization state is associated with changes in cell shape, macrophage morphology is associated with activation status. M1 macrophages appeared large and rounded, while M2 macrophages were stretched and elongated cells. Manipulating cell morphology has been shown to affect the polarization state of macrophages. The shape of the cell is largely dependent on cytoskeletal proteins, especially, microtubules. As a microtubule-targetting drug, vinblastine (VBL) has been used in chemotherapy. However, no study to date has explored the effect of VBL on TAM shape changes and its role in tumor immune response.

METHOD

We used fluorescent staining of the cytoskeleton and quantitative analysis to reveal the morphological differences between M0, M1, M2, TAM and VBL-treated TAM. Flow cytometry was used to confirm the polarization states of these macrophages using a cell surface marker-based classification. In vivo antibody depletion experiments in tumor mouse models were performed to test whether macrophages and CD8+ T cell populations were required for the antitumor effect of VBL. VBL and anti-PD-1 combination therapy was then investigated in comparison with monotherapy. RNA-seq of TAM of treated and untreated with VBL was performed to explore the changes in pathway activities. siRNA mediated knockdown experiments were performed to verify the target pathway that was affected by VBL treatment.

RESULTS

Here, we showed that VBL, an antineoplastic agent that destabilizes microtubule, drove macrophage polarization into the M1-like phenotype both in vitro and in tumor models. The antitumor effect of VBL was attenuated in the absence of macrophages or CD8+ T cells. Mechanistically, VBL induces the activation of NF-κB and Cyba-dependent reactive oxygen species generation, thus polarizing TAMs to the M1 phenotype. In parallel, VBL promotes the nuclear translocation of transcription factor EB, inducing lysosome biogenesis and a dramatic increase in phagocytic activity in macrophages.

CONCLUSIONS

This study explored whether manipulating cellular morphology affects macrophage polarization and consequently induces an antitumor response. Our data reveal a previously unrecognized antitumor mechanism of VBL and suggest a drug repurposing strategy combining VBL with immune checkpoint inhibitors to improve malignant tumor immunotherapy.

Versatile flexible micelles integrating mucosal penetration and intestinal targeting for effectively oral delivery of paclitaxel

The extremely low bioavailability of oral paclitaxel (PTX) mainly due to the complicated gastrointestinal environment, the obstruction of intestinal mucus layer and epithelium barrier. Thus, it is of great significance to construct a coordinative delivery system which can overcome multiple intestinal physicochemical obstacles simultaneously. In this work, a high-density PEGylation-based glycocholic acid-decorated micelles (PTX@GNPs) was constructed by a novel polymer, 9-Fluorenylmethoxycarbonyl-polyethylene glycocholic acid (Fmoc-PEG-GCA). The Fmoc motif in this polymer could encapsulate PTX via π‒π stacking to form the core of micelles, and the low molecular weight and non-long hydrophobic chain of Fmoc ensures the high-density of PEG. Based on this versatile and flexible carriers, PTX@GNPs possess mucus trapping escape ability due to the flexible PEG, and excellent intestine epithelium targeting attributed to the high affinity of GCA with apical sodium-dependent bile acid transporter. The in vitro and in vivo results showed that this oral micelle could enhance oral bioavailability of PTX, and exhibited similar antitumor efficacy to Taxol injection via intravenous route. In addition, oral PTX@GNPs administered with lower dosage within shorter interval could increase in vivo retention time of PTX, which supposed to remodel immune microenvironment and enhance oral chemotherapy efficacy by synergistic effect.

Locally sourced: site-specific immune barriers to metastasis

Tumour cells migrate very early from primary sites to distant sites, and yet metastases often take years to manifest themselves clinically or never even surface within a patient's lifetime. This pause in cancer progression emphasizes the existence of barriers that constrain the growth of disseminated tumour cells (DTCs) at distant sites. Although the nature of these barriers to metastasis might include DTC-intrinsic traits, recent studies have established that the local microenvironment also controls the formation of metastases. In this Perspective, I discuss how site-specific differences of the immune system might be a major selective growth restraint on DTCs, and argue that harnessing tissue immunity will be essential for the next stage in immunotherapy development that reliably prevents the establishment of metastases.

Cathepsin B Is Not an Intrinsic Factor Related to Asparaginase Resistance of the Acute Lymphoblastic Leukemia REH Cell Line

L-Asparaginase (ASNase) is a biopharmaceutical used as an essential drug in the treatment of acute lymphoblastic leukemia (ALL). Yet, some cases of ALL are naturally resistant to ASNase treatment, which results in poor prognosis. The REH ALL cell line, used as a model for studying the most common subtype of ALL, is considered resistant to treatment with ASNase. Cathepsin B (CTSB) is one of the proteases involved in the regulation of in vivo ASNase serum half-life and it has also been associated with the progression and resistance to treatment of several solid tumors. Previous works have shown that, in vitro, ASNase is degraded when incubated with REH cell lysate, which is prevented by a specific CTSB inhibitor, suggesting a function of this protease in the ASNase resistance of REH cells. In this work, we utilized a combination of CRISPR/Cas9 gene targeting and enzymatic measurements to investigate the relevance of CTSB on ASNase treatment resistance in the ALL model cell line. We found that deletion of CTSB in REH ALL cells did not confer ASNase treatment sensitivity, thus suggesting that intrinsic expression of CTSB is not a mechanism that drives the resistant nature of these ALL cells to enzymes used as the first-line treatment against leukemia.

3D Biomimetic Models to Reconstitute Tumor Microenvironment In Vitro: Spheroids, Organoids, and Tumor-on-a-Chip

Decades of efforts in engineering in vitro cancer models have advanced drug discovery and the insight into cancer biology. However, the establishment of preclinical models that enable fully recapitulating the tumor microenvironment remains challenging owing to its intrinsic complexity. Recent progress in engineering techniques has allowed the development of a new generation of in vitro preclinical models that can recreate complex in vivo tumor microenvironments and accurately predict drug responses, including spheroids, organoids, and tumor-on-a-chip. These biomimetic 3D tumor models are of particular interest as they pave the way for better understanding of cancer biology and accelerating the development of new anticancer therapeutics with reducing animal use. Here, the recent advances in developing these in vitro platforms for cancer modeling and preclinical drug screening, focusing on incorporating hydrogels are reviewed to reconstitute physiologically relevant microenvironments. The combination of spheroids/organoids with microfluidic technologies is also highlighted to better mimic in vivo tumors and discuss the challenges and future directions in the clinical translation of such models for drug screening and personalized medicine.

Macrophages in immunoregulation and therapeutics

Macrophages exist in various tissues, several body cavities, and around mucosal surfaces and are a vital part of the innate immune system for host defense against many pathogens and cancers. Macrophages possess binary M1/M2 macrophage polarization settings, which perform a central role in an array of immune tasks via intrinsic signal cascades and, therefore, must be precisely regulated. Many crucial questions about macrophage signaling and immune modulation are yet to be uncovered. In addition, the clinical importance of tumor-associated macrophages is becoming more widely recognized as significant progress has been made in understanding their biology. Moreover, they are an integral part of the tumor microenvironment, playing a part in the regulation of a wide variety of processes including angiogenesis, extracellular matrix transformation, cancer cell proliferation, metastasis, immunosuppression, and resistance to chemotherapeutic and checkpoint blockade immunotherapies. Herein, we discuss immune regulation in macrophage polarization and signaling, mechanical stresses and modulation, metabolic signaling pathways, mitochondrial and transcriptional, and epigenetic regulation. Furthermore, we have broadly extended the understanding of macrophages in extracellular traps and the essential roles of autophagy and aging in regulating macrophage functions. Moreover, we discussed recent advances in macrophages-mediated immune regulation of autoimmune diseases and tumorigenesis. Lastly, we discussed targeted macrophage therapy to portray prospective targets for therapeutic strategies in health and diseases.

The role of tumor microenvironment in drug resistance: emerging technologies to unravel breast cancer heterogeneity

Breast cancer is a highly heterogeneous disease, at both inter- and intra-tumor levels, and this heterogeneity is a crucial determinant of malignant progression and response to treatments. In addition to genetic diversity and plasticity of cancer cells, the tumor microenvironment contributes to tumor heterogeneity shaping the physical and biological surroundings of the tumor. The activity of certain types of immune, endothelial or mesenchymal cells in the microenvironment can change the effectiveness of cancer therapies via a plethora of different mechanisms. Therefore, deciphering the interactions between the distinct cell types, their spatial organization and their specific contribution to tumor growth and drug sensitivity is still a major challenge. Dissecting intra-tumor heterogeneity is currently an urgent need to better define breast cancer biology and to develop therapeutic strategies targeting the microenvironment as helpful tools for combined and personalized treatment. In this review, we analyze the mechanisms by which the tumor microenvironment affects the characteristics of tumor heterogeneity that ultimately result in drug resistance, and we outline state of the art preclinical models and emerging technologies that will be instrumental in unraveling the impact of the tumor microenvironment on resistance to therapies.

Neoadjuvant chemotherapy enhances anti-tumor immune response of tumor microenvironment in human esophageal squamous cell carcinoma

Although chemotherapy has been an essential treatment for cancer, the development of immune checkpoint blockade therapy was revolutionary, and a comprehensive understanding of the immunological tumor microenvironment (TME) has become crucial. Here, we investigated the impact of neoadjuvant chemotherapy (NAC) on immune cells in the TME of human esophageal squamous cell carcinoma using single cell RNA-sequencing. Analysis of 30 fresh samples revealed that CD8+/CD4+ T cells, dendritic cells (DCs), and macrophages in the TME of human esophageal squamous cell carcinoma showed higher levels of an anti-tumor immune response in the NAC(+) group than in the NAC(-) group. Furthermore, the immune cells of the NAC(+) group interacted with each other resulting in enhanced anti-tumor immune response via various cytokines, including IFNG in CD8+/CD4+ T cells, EBI3 in DCs, and NAMPT in macrophages. Our results suggest that NAC potentially enhances the anti-tumor immune response of immune cells in the TME.

Neutrophil extracellular traps formed during chemotherapy confer treatment resistance via TGF-β activation

Metastasis is the major cause of cancer death, and the development of therapy resistance is common. The tumor microenvironment can confer chemotherapy resistance (chemoresistance), but little is known about how specific host cells influence therapy outcome. We show that chemotherapy induces neutrophil recruitment and neutrophil extracellular trap (NET) formation, which reduces therapy response in mouse models of breast cancer lung metastasis. We reveal that chemotherapy-treated cancer cells secrete IL-1β, which in turn triggers NET formation. Two NET-associated proteins are required to induce chemoresistance: integrin-αvβ1, which traps latent TGF-β, and matrix metalloproteinase 9, which cleaves and activates the trapped latent TGF-β. TGF-β activation causes cancer cells to undergo epithelial-to-mesenchymal transition and correlates with chemoresistance. Our work demonstrates that NETs regulate the activities of neighboring cells by trapping and activating cytokines and suggests that chemoresistance in the metastatic setting can be reduced or prevented by targeting the IL-1β-NET-TGF-β axis.

Macrophages at the interface of the co-evolving cancer ecosystem

Macrophages are versatile and heterogeneous innate immune cells undertaking central functions in balancing immune responses and tissue repair to maintain homeostasis. This plasticity, once co-opted by malignant outgrowth, orchestrates manifold reciprocal interactions within the tumor microenvironment, fueling the evolution of the cancer ecosystem. Here, we review the multilayered sources of influence that jointly underpin and longitudinally shape tumor-associated macrophage (TAM) phenotypic states in solid neoplasms. We discuss how, in response to these signals, TAMs steer tumor evolution in the context of natural selection, biological dispersion, and treatment resistance. A number of research frontiers to be tackled are laid down in this review to therapeutically exploit the complex roles of TAMs in cancer. Building upon knowledge obtained from currently applied TAM-targeting strategies and using next generation technologies, we propose conceptual advances and novel therapeutic avenues to rewire TAM multifaceted regulation of the co-evolving cancer ecosystem.