Tumor-associated macrophages employ immunoediting mechanisms in colorectal tumor progression: Current research in Macrophage repolarization immunotherapy

Bufalin inhibits immune escape in metastatic colorectal cancer by regulating M2 macrophage polarization

The prognosis for patients with metastatic colorectal cancer (mCRC) remains poor primarily owing to immune escape caused by immunosuppressive tumor microenvironment (TME). M2 tumor-associated macrophages (TAMs) have been considered as a pivotal role in sustaining the immunosuppressive character in TME. Our previous studies have found that highly mCRC cells could promote M2 TAMs polarization, leading to the exhaustion of T cell antitumor immunity. Studies have reported that Bufalin (BU) could reverse the immunosuppressive TME via regulating TAMs polarization, but the mechanisms underlying remain elusive. In this study, we demonstrated that KLF4 secreted by highly mCRC cells not only promoted the polarization to M2 TAMs but also up-regulated the PD-L1 expression in TAMs, leading to suppressing cytotoxic T lymphocyte (CTL) function to facilitate tumor immune escape. Mechanistically, BU targeted the SRC-3 protein to reduce KLF4 release in highly mCRC cells to regulate the polarization of M2 TAMs and down-regulate PD-L1 expression in TAMs, resulting in reprogramming of the TME and enhancing the anti-tumor immunity. These results have also been validated in both subcutaneous tumor models and orthotopic tumor models. Overall, this research further elucidates the anti-tumor mechanism of BU for inhibiting immune escape in mCRC and facilitate exploitation of a new potential macrophage-based mCRC immunotherapeutic modality.

Regulation and Function of Tumor-Associated Macrophages (TAMs) in Colorectal Cancer (CRC): The Role of the SRIF System in Macrophage Regulation

Colorectal cancer (CRC) remains the leading cause of morbidity and mortality for both men and women worldwide. Tumor-associated macrophages (TAMs) are the most abundant immune cells in the tumor microenvironment (TME) of solid tumors, including CRC. These macrophages are found in the pro-inflammatory M1 and anti-inflammatory M2 forms, with the latter increasingly recognized for its tumor-promoting phenotypes. Many signaling molecules and pathways, including AMPK, EGFR, STAT3/6, mTOR, NF-κB, MAPK/ERK, and HIFs, are involved in regulating TAM polarization. Consequently, researchers are investigating several potential predictive and prognostic markers, and novel TAM-based therapeutic targets, especially in combination therapies for CRC. Macrophages of the gastrointestinal tract, including the normal colon and rectum, produce growth hormone-releasing inhibitory peptide/somatostatin (SRIF/SST) and five SST receptors (SSTRs, SST1-5). While the immunosuppressive function of the SRIF system is primarily known for various tissues, its role within CRC-associated TAMs remains underexplored. This review focuses on the following three aspects of TAMs: first, the role of macrophages in the normal colon and rectum within the broader context of macrophage biology; second, the various bioactive factors and signaling pathways associated with TAM function, along with potential strategies targeting TAMs in CRC; and third, the interaction between the SRIF system and macrophages in both normal tissues and the CRC microenvironment.

Emerging nanomedicines for macrophage-mediated cancer therapy

Tumor-associated macrophages (TAMs) contribute to tumor progression by promoting angiogenesis, remodeling the tumor extracellular matrix, inducing tumor invasion and metastasis, as well as immune evasion. Due to the high plasticity of TAMs, they can polarize into different phenotypes with distinct functions, which are primarily categorized as the pro-inflammatory, anti-tumor M1 type, and the anti-inflammatory, pro-tumor M2 type. Notably, anti-tumor macrophages not only directly phagocytize tumor cells, but also present tumor-specific antigens and activate adaptive immunity. Therefore, targeted regulation of TAMs to unleash their potential anti-tumor capabilities is crucial for improving the efficacy of cancer immunotherapy. Nanomedicine serves as a promising vehicle and can inherently interact with TAMs, hence, emerging as a new paradigm in cancer immunotherapy. Due to their controllable structures and properties, nanomedicines offer a plethora of advantages over conventional drugs, thus enhancing the balance between efficacy and toxicity. In this review, we provide an overview of the hallmarks of TAMs and discuss nanomedicines for targeting TAMs with a focus on inhibiting recruitment, depleting and reprogramming TAMs, enhancing phagocytosis, engineering macrophages, as well as targeting TAMs for tumor imaging. We also discuss the challenges and clinical potentials of nanomedicines for targeting TAMs, aiming to advance the exploitation of nanomedicine for cancer immunotherapy.

SIRPα + CD209 + cell: a specialized antigen-presenting cell that contributes to anti-SIRPα/RT therapy in colorectal cancer

OBJECTIVE

Colorectal cancer (CRC) is a leading cause of cancer-related mortality, with a need for improved treatment strategies. Antigen-presenting cells (APCs) have emerged as important modulators of immune responses in the tumor microenvironment (TME). This study aimed to explore the role of these cells in CRC and their potential synergy with radiation therapy (RT).

METHODS

Single-cell sequencing was performed before and after neoadjuvant therapy (NAT) to identify changes in myeloid cells within the tumor microenvironment, which was compared with peripheral blood of the same patients. The effect of RT with/without immunotherapy on these cells was evaluated in vivo and in vitro.

RESULTS

Single-cell sequencing showed that SIRPα + CD209 + cells are specialized antigen-presenting cells which are found to decrease in the TME while increasing in the peripheral blood after NAT. In vitro study confirmed their resistance to RT with further upregulated SIRPα expression and enhanced antigen presentation capability induced by RT. Moreover, these cells are involved in the superior tumor control by combination of RT and anti-SIRPα treatment.

CONCLUSION

SIRPα + CD209 + APCs play a pivotal role in CRC immune modulation and show potential for synergy with RT. These cells could be a biomarker for antigen-presenting capacity, and enhancing their APC function could potentially improve RT/PD1 effectiveness by combination with anti-SIRPα in CRC.

The role of type I interferon signaling in myeloid anti-tumor immunity

Tumors often arise in chronically inflamed, and thus immunologically highly active niches. While immune cells are able to recognize and remove transformed cells, tumors eventually escape the control of the immune system by shaping their immediate microenvironment. In this context, macrophages are of major importance, as they initially exert anti-tumor functions before they adopt a tumor-associated phenotype that instead inhibits anti-tumor immune responses and even allows for sustaining a smoldering inflammatory, growth promoting tumor microenvironment (TME). Type I interferons (IFNs) are well established modulators of inflammatory reactions. While they have been shown to directly inhibit tumor growth, there is accumulating evidence that they also play an important role in altering immune cell functions within the TME. In the present review, we focus on the impact of type I IFNs on anti-tumor responses, driven by monocytes and macrophages. Specifically, we will provide an overview of tumor-intrinsic factors, which impinge on IFN-stimulated gene (ISG) expression, like the presence of nucleic acids, metabolites, or hypoxia. We will further summarize the current understanding of the consequences of altered IFN responses on macrophage phenotypes, i.e., differentiation, polarization, and functions. For the latter, we will focus on macrophage-mediated tumor cell killing and phagocytosis, as well as on how macrophages affect their environment by secreting cytokines and directly interacting with immune cells. Finally, we will discuss how type I IFN responses in macrophages might affect and should be considered for current and future tumor therapies.

From silent partners to potential therapeutic targets: macrophages in colorectal cancer

Cancer cells grow and survive in the tumor microenvironment, which is a complicated process. As a key part of how colorectal cancer (CRC) progresses, tumor-associated macrophages (TAMs) exhibit a double role. Through angiogenesis, this TAM can promote the growth of cancers. Although being able to modify and adjust immune cells is a great advantage, these cells can also exhibit anti-cancer properties including direct killing of cancer cells, presenting antigens, and aiding T cell-mediated responses. The delicate regulatory mechanisms between the immune system and tumors are composed of a complex network of pathways regulated by several factors including hypoxia, metabolic reprogramming, cytokine/chemokine signaling, and cell interactions. Decoding and figuring out these complex systems become significant in building targeted treatment programs. Targeting TAMs in CRC involves disrupting chemokine signaling or adhesion molecules, reprogramming them to an anti-tumor phenotype using TLR agonists, CD40 agonists, or metabolic modulation, and selectively removing TAM subsets that promote tumor growth. Multi-drug resistance, the absence of an accurate biomarker, and drug non-specificity are also major problems. Combining macrophage-targeted therapies with chemotherapy and immunotherapy may revolutionize treatment. Macrophage studies will advance with new technology and multi-omics methodologies to help us understand CRC and build specific and efficient treatments.

Investigating the Role of Quercetin, an Active Ingredient in Bazhen Decoction, in Targeting CXCL8 to Inhibit Macrophage M2 Polarization and Reshape the Immunological Microenvironment of Colorectal Cancer

Bazhen Decoction (Eight Treasures Decoction) has demonstrated efficacy in the treatment of colorectal cancer (CRC), yet the active ingredients in it and the mechanisms underlying their anti-cancer properties are not well understood. Through network pharmacology, the effective components of Bazhen Decoction against CRC and their corresponding key genes were delineated. Molecular docking was executed to identify the active component targeting the key gene CXCL8, which led to the discovery of Quercetin. The cellular thermal shift assay method was then used to verify the binding interaction. CRC cells were treated with incremental concentrations of Quercetin, cell viability was evaluated by the Cell Counting Kit-8 assay to calculate the IC50, and apoptosis rates were determined by flow cytometry. Expression of the apoptosis-related proteins Bcl-2 and Cleaved caspase-3 was measured using western blot. The impact of Quercetin on macrophage polarization was studied by co-culturing the treated CRC cells with macrophages, assessing M1 and M2 macrophage distribution via flow cytometry, and quantifying cytokine levels (IL-6, IL-10, IL-12, and CXCL8) with enzyme-linked immunosorbent assay (ELISA). The active ingredient Quercetin from Bazhen Decoction exhibited a targeted binding affinity with the key gene CXCL8, which enabled it to inhibit the proliferation of CRC cells and induce cell apoptosis. The overexpression of CXCL8 was associated with the promotion of CRC malignancy, yet the presence of Quercetin could lessen the impact of CXCL8 overexpression on CRC cells. Moreover, the treatment with Quercetin leads to a diminished abundance of M2 macrophages and an increase in the levels of cytokines IL-6 and IL-12, while reducing the levels of IL-10 and CXCL8, which indicates that Quercetin has an inhibitory effect on macrophage M2 polarization. Quercetin, the active component in Bazhen Decoction that is known for anti-CRC effects, targets and inhibits CXCL8 to impede the malignant behaviors and the M2 polarization of macrophages. Thus, Quercetin may be utilized as an immunomodulatory agent in CRC treatment.

Inosine Prevents Colorectal Cancer Progression by Inducing M1 Phenotypic Polarization of Macrophages

Inosine (IS) is a naturally occurring metabolite of adenosine with potent immunomodulatory effects. This study investigates the immunomodulatory effects of inosine, particularly its ability to inhibit the development of colorectal cancer (CRC) cells CT26 through modulation of macrophage phenotypes. Aside from the already reported effects of inosine on T cells, in this study, in vitro experiments revealed that inosine could modulate macrophage phenotype. The effects of inosine on the M1/M2 macrophage polarization were investigated at the cellular level. Its role in regulating CRC proliferation and migration was further examined. In addition, a CT26 tumor mouse model was established to assess the mechanism of action of inosine by tumor weight measurement, immunohistochemistry, and immunofluorescence. Inosine significantly increased M1 macrophage markers CD86 and iNOS and enhanced the anti-tumor activity of M1 macrophages, effectively inhibiting CRC progression and metastasis potential. In vivo, inosine had significant tumor inhibitory activity. It also significantly reduced the expression of Ki-67 and promoted the polarization of M1 macrophages.

Tumor microenvironment remodeling after neoadjuvant chemoradiotherapy in local advanced rectal cancer revealed by single-cell RNA sequencing

BACKGROUND

The use of neoadjuvant chemoradiotherapy (neoCRT) followed by surgery has markedly enhanced the quality of survival in patients suffering from local advanced rectal cancer (LARC). Enhancing this treatment requires a deep understanding of its underlying mechanism. The heterogeneous nature of the tumor microenvironment (TME) significantly impacts therapeutic responses, presenting complex therapeutic challenges.

METHODS

In this comprehensive study, we explored the intricate cellular and molecular shifts within the TME of LARC after neoCRT administration. Using single-cell transcriptomic analysis, we meticulously examined 32,417 cells sourced from six samples, each representing different tumor regression grades (TRG: 0 versus 2). This detailed analysis enabled us to characterize the various cell subpopulations, encompassing epithelial cells, lymphocytes, myeloid cells, endothelial cells, and fibroblasts. Additionally, we identified their marker genes for deconvolution calculation in the READ cohort of the TCGA project. And we obtain their marker genes for deconvolution calculation in the READ cohort of the TCGA project.

RESULTS

Through cluster analysis and pathway comparisons of malignant tumor cells, we discerned that samples with poor tumor regression exhibit enhanced metabolic versatility and adaptability, enabling them to counteract the impacts of both radiotherapy and chemotherapy. Interestingly, within the TRG2 cohort, we observed a predominant immunosuppressive state in the TME, characterized by the activation of CD4 + regulatory T cells, maintained CD8 + T cell functionality, and a heightened M1 to M2 macrophage ratio. Moreover, the differing outcomes of neoCRT were reflected in the varying interaction dynamics between macrophages (M1 and M2) and CD4+/CD8 + T cells. Furthermore, our data reveal that neoCRT intricately modulates fibroblasts and endothelial cells, primarily through the extracellular matrix remodeling pathway, which orchestrates tumor angiogenesis. All changes were validated through immunofluorescence staining on intraoperative samples before and after treatment. To summarize, our investigation presents a comprehensive exploration of the cellular and molecular metamorphoses within the TME post-neoCRT.

CONCLUSIONS

By unveiling the sophisticated interaction between the multifaceted cells within the TME and their respective reactions to neoCRT, we establish a robust platform for ensuing future investigations. This study paves the way for novel therapeutic strategies that leverage these insights to bolster the efficacy of neoCRT in managing LARC.

Natural compounds modulate the mechanism of action of tumour-associated macrophages against colorectal cancer: a review

Colorectal cancer (CRC) exhibits a substantial morbidity and mortality rate, with its aetiology and pathogenesis remain elusive. It holds significant importance within the tumour microenvironment (TME) and exerts a crucial regulatory influence on tumorigenesis, progression, and metastasis. TAMs possess the capability to foster CRC pathogenesis, proliferation, invasion, and metastasis, as well as angiogenesis, immune evasion, and tumour resistance. Furthermore, TAMs can mediate the prognosis of CRC. In this paper, we review the mechanisms by which natural compounds target TAMs to exert anti-CRC effects from the perspective of the promotional effects of TAMs on CRC, mainly regulating the polarization of TAMs, reducing the infiltration and recruitment of TAMs, enhancing the phagocytosis of macrophages, and regulating the signalling pathways and cytokines, and discuss the potential value and therapeutic strategies of natural compounds-targeting the TAMs pathway in CRC clinical treatment.

Research progress of tumor-associated macrophages in immune checkpoint inhibitor tolerance in colorectal cancer

The relevant mechanism of tumor-associated macrophages (TAMs) in the treatment of colorectal cancer patients with immune checkpoint inhibitors (ICIs) is discussed, and the application prospects of TAMs in reversing the treatment tolerance of ICIs are discussed to provide a reference for related studies. As a class of drugs widely used in clinical tumor immunotherapy, ICIs can act on regulatory molecules on cells that play an inhibitory role-immune checkpoints-and kill tumors in the form of an immune response by activating a variety of immune cells in the immune system. The sensitivity of patients with different types of colorectal cancer to ICI treatment varies greatly. The phenotype and function of TAMs in the colorectal cancer microenvironment are closely related to the efficacy of ICIs. ICIs can regulate the phenotypic function of TAMs, and TAMs can also affect the tolerance of colorectal cancer to ICI therapy. TAMs play an important role in ICI resistance, and making full use of this target as a therapeutic strategy is expected to improve the immunotherapy efficacy and prognosis of patients with colorectal cancer.

Resveratrol: biology, metabolism, and detrimental role on the tumor microenvironment of colorectal cancer

A substantial increase in colorectal cancer (CRC)-associated fatalities can be attributed to tumor recurrence and multidrug resistance. Traditional treatment options, including radio- and chemotherapy, also exhibit adverse side effects. Ancient treatment strategies that include phytochemicals like resveratrol are now widely encouraged as an alternative therapeutic option. Resveratrol is the natural polyphenolic stilbene in vegetables and fruits like grapes and apples. It inhibits CRC progression via targeting dysregulated cancer-promoting pathways, including PI3K/Akt/Kras, targeting transcription factors like NF-κB and STAT3, and an immunosuppressive tumor microenvironment. In addition, combination therapies for cancer include resveratrol as an adjuvant to decrease multidrug resistance that develops in CRC cells. The current review discusses the biology of resveratrol and explores different mechanisms of action of resveratrol in inhibiting CRC progression. Further, the detrimental role of resveratrol on the immunosuppressive tumor microenvironment of CRC has been discussed. This review illustrates clinical trials on resveratrol in different cancers, including resveratrol analogs, and their efficiency in promoting CRC inhibition.

Unraveling the relationship between anoikis-related genes and cancer-associated fibroblasts in liver hepatocellular carcinoma

This study intended to determine the molecular subtypes of liver hepatocellular carcinoma (LIHC) on the strength of anoikis-related genes (ARGs) and to assess their prognostic value and prospective relationship with immune cell infiltration and cancer-associated fibroblasts (CAFs). Univariate Cox regression analysis yielded 66 prognosis-related ARGs and classified LIHC into two distinct subtypes, with subtype A demonstrating overexpression of most prognosis-related ARGs and a significant survival disadvantage. Furthermore, a reliable prediction model was developed using ARGs to evaluate the risk of LIHC patients. This model served as an independent prognostic indicator and a quantitative tool for clinical prognostic prediction. Additionally, subtype-specific differences in immune cell infiltration were observed, and the risk score was potentially linked to immune-related characteristics. Moreover, the study identified a significant association between CAF score and LIHC prognosis, with a low CAF score indicating a favorable patient prognosis. In conclusion, this study reveals the molecular mechanisms underlying the development and progression of LIHC and identifies potential therapeutic targets for the disease.

Tumor-associated macrophages derived exosomes; from pathogenesis to therapeutic opportunities

Tumor-associated macrophages (TAMs) exert profound influences on cancer progression, orchestrating a dynamic interplay within the tumor microenvironment. Recent attention has focused on the role of TAM-derived exosomes, small extracellular vesicles containing bioactive molecules, in mediating this intricate communication. This review comprehensively synthesizes current knowledge, emphasizing the diverse functions of TAM-derived exosomes across various cancer types. The review delves into the impact of TAM-derived exosomes on fundamental cancer hallmarks, elucidating their involvement in promoting cancer cell proliferation, migration, invasion, and apoptosis evasion. By dissecting the molecular cargo encapsulated within these exosomes, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and proteins, the review uncovers key regulatory mechanisms governing these effects. Noteworthy miRNAs, such as miR-155, miR-196a-5p, and miR-221-3p, are highlighted for their pivotal roles in mediating TAM-derived exosomal communication and influencing downstream targets. Moreover, the review explores the impact of TAM-derived exosomes on the immune microenvironment, particularly their ability to modulate immune cell function and foster immune evasion. The discussion encompasses the regulation of programmed cell death ligand 1 (PD-L1) expression and subsequent impairment of CD8 + T cell activity, unraveling the immunosuppressive effects of TAM-derived exosomes. With an eye toward clinical implications, the review underscores the potential of TAM-derived exosomes as diagnostic markers and therapeutic targets. Their involvement in cancer progression, metastasis, and therapy resistance positions TAM-derived exosomes as key players in reshaping treatment strategies. Finally, the review outlines future directions, proposing avenues for targeted therapies aimed at disrupting TAM-derived exosomal functions and redefining the tumor microenvironment.

The role of CD8+ T-cells in colorectal cancer immunotherapy

Immunotherapy has been an advanced and effective approach to treating various types of solid tumors in recent years, and the most successful strategy is immune checkpoint inhibitors (ICIs), which have shown beneficial effects in patients with colorectal cancer (CRC). Drug resistance to ICIs is usually associated with CD8+ T-cells targeting tumor antigens; thus, CD8+ T-cells play an important role in immunotherapy. Unfortunately, Under continuous antigen stimulation, tumor microenvironment(TME), hypoxia and other problems it leads to insufficient infiltration of CD8+ T-cells, low efficacy and mechanism exhaustion, which have become obstacles to immunotherapy. Thus, this article describes the relationship between CRC and the immune system, focuses on the process of CD8+ T-cells production, activation, transport, killing, and exhaustion, and expounds on related mechanisms leading to CD8+ T-cells exhaustion. Finally, this article summarizes the latest strategies and methods in recent years, focusing on improving the infiltration, efficacy, and exhaustion of CD8+ T-cells, which may help to overcome the barriers to immunotherapy.

Berberine: Potential preventive and therapeutic strategies for human colorectal cancer

Colorectal cancer (CRC) is a common digestive tract tumor, with incidences continuing to rise. Although modern medicine has extended the survival time of CRC patients, its adverse effects and the financial burden cannot be ignored. CRC is a multi-step process and can be caused by the disturbance of gut microbiome and chronic inflammation's stimulation. Additionally, the presence of precancerous lesions is also a risk factor for CRC. Consequently, scientists are increasingly interested in identifying multi-target, safe, and economical herbal medicine and natural products. This paper summarizes berberine's (BBR) regulatory mechanisms in the occurrence and development of CRC. The findings indicate that BBR regulates gut microbiome homeostasis and controls mucosal inflammation to prevent CRC. In the CRC stage, BBR inhibits cell proliferation, invasion, and metastasis, blocks the cell cycle, induces cell apoptosis, regulates cell metabolism, inhibits angiogenesis, and enhances chemosensitivity. BBR plays a role in the overall management of CRC. Therefore, using BBR as an adjunct to CRC prevention and treatment could become a future trend in oncology.

Relationship of FDG PET/CT imaging features with tumor immune microenvironment and prognosis in colorectal cancer: a retrospective study

BACKGROUND

Imaging features of colorectal cancers on 2-deoxy-2-[18F]fluoro-d-glucose (FDG) positron emission tomography/computed tomography (PET/CT) have been considered to be affected by tumor characteristics and tumor immune microenvironment. However, the relationship between PET/CT imaging features and immune reactions in tumor tissue has not yet been fully evaluated. This study investigated the association of FDG PET/CT imaging features in the tumor, bone marrow, and spleen with immunohistochemical results of cancer tissue and recurrence-free survival (RFS) in patients with colorectal cancer.

METHODS

A total of 119 patients with colorectal cancer who underwent FDG PET/CT for staging work-up and received curative surgical resection were retrospectively enrolled. From PET/CT images, 10 first-order imaging features of primary tumors, including intensity of FDG uptake, volumetric metabolic parameters, and metabolic heterogeneity parameters, as well as FDG uptake in the bone marrow and spleen were measured. The degrees of CD4+, CD8+, and CD163 + cell infiltration and interleukin-6 (IL-6) and matrix metalloproteinase-11 (MMP-11) expression were graded through immunohistochemical analysis of surgical specimens. The relationship between FDG PET/CT imaging features and immunohistochemical results was assessed, and prognostic significance of PET/CT imaging features in predicting RFS was evaluated.

RESULTS

Correlation analysis with immunohistochemistry findings showed that the degrees of CD4 + and CD163 + cell infiltration and IL-6 and MMP-11 expression were correlated with cancer imaging features on PET/CT. Patients with enhanced inflammatory response in cancer tissue demonstrated increased FDG uptake, volumetric metabolic parameters, and metabolic heterogeneity. FDG uptake in the bone marrow and spleen was positively correlated with the degree of CD163 + cell infiltration and IL-6 expression, respectively. In multivariate survival analysis, the coefficient of variation of FDG uptake in the tumor (p = 0.019; hazard ratio, 0.484 for 0.10 increase) and spleen-to-liver uptake ratio (p = 0.020; hazard ratio, 24.901 for 1.0 increase) were significant independent predictors of RFS.

CONCLUSIONS

The metabolic heterogeneity of tumors and FDG uptake in the spleen were correlated with tumor immune microenvironment and showed prognostic significance in predicting RFS in patients with colorectal cancer.

Oncolytic virus-based combination therapy in breast cancer

Breast cancer continues to pose significant challenges in the field of oncology, necessitating innovative treatment approaches. Among these, oncolytic viruses have emerged as a promising frontier in the battle against various types of cancer, including breast cancer. These viruses, often genetically modified, have the unique ability to selectively infect and destroy cancer cells while leaving healthy cells unharmed. Their efficacy in tumor eradication is not only owing to direct cell lysis but also relies on their capacity to activate the immune system, thereby eliciting a potent and sustained antitumor response. While oncolytic viruses represent a significant advancement in cancer treatment, the complexity and adaptability inherent to cancer require a diverse array of therapies. The concept of combining oncolytic viruses with other treatment modalities, such as chemotherapy, immunotherapy, and targeted therapies, has received significant attention. This synergistic approach capitalizes on the strengths of each therapy, thus creating a comprehensive strategy to tackle the heterogeneous and evolving nature of breast cancer. The purpose of this review is to provide an in-depth discussion of preclinical and clinical viro-based combination therapy in the context of breast cancer.

23-Hydroxybetulinic acid attenuates 5-fluorouracil resistance of colorectal cancer by modulating M2 macrophage polarization via STAT6 signaling

Macrophage polarization is closely associated with the inflammatory processes involved in the development and chemoresistance of colorectal cancer (CRC). M2 macrophages, the predominant subtype of tumor-associated macrophages (TAMs) in a wide variety of malignancies, have been demonstrated to promote the resistance of CRC to multiple chemotherapeutic drugs, such as 5-fluorouracil (5-FU). In our study, we investigated the potential of 23-Hydroxybetulinic Acid (23-HBA), a significant active component of Pulsatilla chinensis (P. chinensis), to inhibit the polarization of M2 macrophages induced by IL-4. Our results showed that 23-HBA reduced the expression of M2 specific marker CD206, while downregulating the mRNA levels of M2 related genes (CD206, Arg1, IL-10, and CCL2). Additionally, 23-HBA effectively attenuated the inhibitory effects of the conditioned medium from M2 macrophages on apoptosis in colorectal cancer SW480 cells. Mechanistically, 23-HBA prevented the phosphorylation and nuclear translocation of the STAT6 protein, resulting in the inhibition of IL-10 release in M2 macrophages. Moreover, it interfered with the activation of the IL-10/STAT3/Bcl-2 signaling pathway in SW480 cells, ultimately reducing M2 macrophage-induced resistance to 5-FU. Importantly, depleting STAT6 expression in macrophages abolished the suppressive effect of 23-HBA on M2 macrophage polarization, while also eliminating its ability to decrease M2 macrophage-induced 5-FU resistance in cancer cells. Furthermore, 23-HBA significantly diminished the proportion of M2 macrophages in the tumor tissues of colorectal cancer mice, simultaneously enhancing the anti-cancer efficacy of 5-FU. The findings presented in this study highlight the capacity of 23-HBA to inhibit M2 macrophage polarization, a process that contributes to reduced 5-FU resistance in colorectal cancer.

Siglec9 + tumor-associated macrophages predict prognosis and therapeutic vulnerability in patients with colon cancer

BACKGROUND

Siglec9 has been identified as an immune checkpoint molecule on tumor-associated macrophages (TAMs). Nevertheless, the expression profile and clinical significance of Siglec9 + TAMs in colon cancer (CC) are still not fully understood.

METHODS

Two clinical cohorts from distinct medical centers were retrospectively enrolled. Immunohistochemistry and immunofluorescence were conducted to evaluate the infiltration of immune cells. Single-cell RNA sequencing and flow cytometry were utilized to identify the impact of Siglec9 + TAMs on the tumor immune environment, which was subsequently validated through bioinformatics analysis of the TCGA database. Prognosis and the benefit of adjuvant chemotherapy (ACT) were also evaluated using Cox regression analysis and the Kaplan-Meier method.

RESULTS

High infiltration of Siglec9 + TAMs was associated with worse prognosis and better benefit from 6-month ACT. Siglec9 + TAMs contributed to immunoevasion by promoting the infiltration of immunosuppressive cells and the dysfunction process of CD8 + T cells. Additionally, high infiltration of Siglec9 + TAMs was associated with the mesenchymal-featured subtype and overexpression of the VEGF signaling pathway, which was validated by the strongest communication between Siglec9 + TAMs and vascular endothelial cells.

CONCLUSIONS

Siglec9 + TAMs may serve as a biomarker for prognosis and response to ACT in CC. Furthermore, the immunoevasive contexture and angiogenesis stimulated by Siglec9 + TAMs suggest potential treatment combinations for CC patients.

The promising role of tumor-associated macrophages in the treatment of cancer

Macrophages are important components of the immune system. Mature macrophages can be recruited to tumor microenvironment that affect tumor cell proliferation, invasion and metastasis, extracellular matrix remodeling, immune suppression, as well as chemotherapy resistance. Classically activated type I macrophages (M1) exhibited marked tumor killing and phagocytosis. Therefore, using macrophages for adoptive cell therapy has attracted attention and become one of the most effective strategies for cancer treatment. Through cytokines and/or chemokines, macrophage can inhibit myeloid cells recruitment, and activate anti-tumor and immune killing functions. Applying macrophages for anti-tumor delivery is one of the most promising approaches for cancer therapy. This review article introduces the role of macrophages in tumor development and drug resistance, and the possible clinical application of targeting macrophages for overcoming drug resistance and enhancing cancer therapeutics, as well as its challenges.

Tumor associated macrophages in esophageal squamous carcinoma: Promising therapeutic implications

Esophageal squamous carcinoma (ESCC) is a prevalent and highly lethal malignant tumor, with a five-year survival rate of approximately 20 %. Tumor-associated macrophages (TAMs) are the most prominent immune cells in the tumor microenvironment (TME), comprising over 50 % of the tumor volume. TAMs can be polarized into two distinct phenotypes, M1-type and M2-type, through interactions with cancer cells. M2-type TAMs are more abundant than M1-type TAMs in the TME, contributing to tumor progression, such as tumor cell survival and the construction of an immunosuppressive environment. This review focuses on the role of TAMs in ESCC, including their polarization, impact on tumor proliferation, angiogenesis, invasion, migration, therapy resistance, and immunosuppression. In addition, we discuss the potential of targeting TAMs for clinical therapy in ESCC. A thorough comprehension of the molecular biology about TAMs is essential for the development of innovative therapeutic strategies to treat ESCC.

Tumor-associated macrophages: Potential therapeutic targets and diagnostic markers in cancer

Macrophages are plastic and functionally diverse, present in all tissues, and play a key role in organisms from development, homeostasis and repair, to immune responses to pathogens. They are central to many disease states and have emerged as important therapeutic targets for many diseases. Tumor-associated macrophages (TAMs) are the most abundant immune cells in the tumor microenvironment (TME) and are key factors influencing cancer progression, metastasis and tumor recurrence. TAMs can be derived from different sources and exert different pro- or anti-tumor effects based on the type, stage and immune composition of the tumor. TAMs are highly heterogeneous and diverse, and have multiple functional phenotypes. There is still a great deal of controversy regarding the relationship between TAMs and prognosis of cancer patients. In this review, we summarize the characteristics of common markers of TAMs as well as explore the prognostic role of TAMs in different cancers including lung, breast, gastric, colorectal, esophageal and ovarian cancers.

From Chaos to Opportunity: Decoding Cancer Heterogeneity for Enhanced Treatment Strategies

Cancer manifests as a multifaceted disease, characterized by aberrant cellular proliferation, survival, migration, and invasion. Tumors exhibit variances across diverse dimensions, encompassing genetic, epigenetic, and transcriptional realms. This heterogeneity poses significant challenges in prognosis and treatment, affording tumors advantages through an increased propensity to accumulate mutations linked to immune system evasion and drug resistance. In this review, we offer insights into tumor heterogeneity as a crucial characteristic of cancer, exploring the difficulties associated with measuring and quantifying such heterogeneity from clinical and biological perspectives. By emphasizing the critical nature of understanding tumor heterogeneity, this work contributes to raising awareness about the importance of developing effective cancer therapies that target this distinct and elusive trait of cancer.

Cellular and Molecular Mechanisms of the Tumor Stroma in Colorectal Cancer: Insights into Disease Progression and Therapeutic Targets

Colorectal cancer (CRC) is a major health burden worldwide and is the third most common type of cancer. The early detection and diagnosis of CRC is critical to improve patient outcomes. This review explores the intricate interplay between the tumor microenvironment, stromal interactions, and the progression and metastasis of colorectal cancer. The review begins by assessing the gut microbiome's influence on CRC development, emphasizing its association with gut-associated lymphoid tissue (GALT). The role of the Wnt signaling pathway in CRC tumor stroma is scrutinized, elucidating its impact on disease progression. Tumor budding, its effect on tumor stroma, and the implications for patient prognosis are investigated. The review also identifies conserved oncogenic signatures (COS) within CRC stroma and explores their potential as therapeutic targets. Lastly, the seed and soil hypothesis is employed to contextualize metastasis, accentuating the significance of both tumor cells and the surrounding stroma in metastatic propensity. This review highlights the intricate interdependence between CRC cells and their microenvironment, providing valuable insights into prospective therapeutic approaches targeting tumor-stroma interactions.

KCND2: A prognostic biomarker and regulator of immune function in gastric cancer

BACKGROUND

Gastric cancer is a highly heterogeneous disease, which makes it challenging to develop effective targeted therapies. Although the potassium voltage-gated channel subfamily D (KCND) channels, particularly KCND2 (also known as Kv4.2), have found evidence of involvement in the occurrence and development of various cancers, there are still some limitations in our understanding of KCND2's roles in gastric cancer.

METHODS

We analyzed the correlation between KCND2 expression and clinical features as well as immune infiltration using the Cancer Genome Atlas (TCGA) database. Functional assays of KCND2 were conducted using Cell counting Kit-8 (CCK8), clone formation assay and cell cycle analysis. Additionally, immunofluorescence, flow cytometry and quantitative real-time polymerase chain reaction (qRT-PCR) techniques were used to investigate tumor proliferation and immune cell infiltration at different levels of KCND2 expression in vivo.

RESULTS

KCND2 was markedly elevated in gastric cancer and its expression appeared to link to different grades, T stages, and N stages. In addition, KCND2 was an independent predictor of prognosis, and its elevated levels in TCGA database revealed a more unfavorable prognosis for patients with gastric cancer. KCND2 strengthened the viability at the cellular level by boosting the proliferation of gastric cancer cells and reducing their death rate. Additionally, it also highlights that KCND2 the abilities of proliferating of gastric cancer cells by stimulating NF-κB both in cell and animal levels. In addition, the findings provided proof that in animal levels, KCND2 might regulate the immune system by associating with promoting M2 macrophages, which are known to play critical roles in cancer progression. Mechanistically, KCND2 was found to lead to the infiltration of M2 macrophages through activation of NF-κB, ultimately promoting the advancement of gastric cancer.

CONCLUSION

Overall, these findings suggest that KCND2 is likely to be available as an underlying therapeutic target for gastric cancer.

Immuno-Contexture and Immune Checkpoint Molecule Expression in Mismatch Repair Proficient Colorectal Carcinoma

Colorectal carcinoma (CRC) represents a lethal disease with heterogeneous outcomes. Only patients with mismatch repair (MMR) deficient CRC showing microsatellite instability and hyper-mutated tumors can obtain clinical benefits from current immune checkpoint blockades; on the other hand, immune- or target-based therapeutic strategies are very limited for subjects with mismatch repair proficient CRC (CRC^pMMR). Here, we report a comprehensive typing of immune infiltrating cells in CRC^pMMR. We also tested the expression and interferon-γ-modulation of PD-L1/CD274. Relevant findings were subsequently validated by immunohistochemistry on fixed materials. CRC^pMMR contain a significantly increased fraction of CD163⁺ macrophages (TAMs) expressing TREM2 and CD66⁺ neutrophils (TANs) together with decrease in CD4^-CD8^-CD3⁺ double negative T lymphocytes (DNTs); no differences were revealed by the analysis of conventional and plasmacytoid dendritic cell populations. A fraction of tumor-infiltrating T-cells displays an exhausted phenotype, co-expressing PD-1 and TIM-3. Remarkably, expression of PD-L1 on fresh tumor cells and TAMs was undetectable even after in vitro stimulation with interferon-γ. These findings confirm the immune suppressive microenvironment of CRC^pMMR characterized by dense infiltration of TAMs, occurrence of TANs, lack of DNTs, T-cell exhaustion, and interferon-γ unresponsiveness by host and tumor cells. Appropriate bypass strategies should consider these combinations of immune escape mechanisms in CRC^pMMR.

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.