Tumor-Educated Neutrophils Activate Mesenchymal Stem Cells to Promote Gastric Cancer Growth and Metastasis

Signaling crosstalk between mesenchymal stem cells and tumor cells: Implications for tumor suppression or progression

Mesenchymal stem cells (MSCs) have been extensively used in various therapeutic applications over the last two decades, particularly in regenerative medicine and cancer treatment. MSCs have the ability to differentiate into mesodermal and non-mesodermal lineages, which makes them a popular choice in tissue engineering and regenerative medicine. Studies have shown that MSCs have inherent tumor-suppressive properties and can affect the behavior of multiple cells contributing to tumor development. Additionally, MSCs possess a tumor tropism property and have a hypoimmune nature. The intrinsic features of MSCs along with their potential to undergo genetic manipulation and be loaded with various anticancer therapeutics have motivated researchers to use them in different cancer therapy approaches without considering their complex dynamic biological aspects. However, despite their desirable features, several reports have shown that MSCs possess tumor-supportive properties. These contradictory results signify the sophisticated nature of MSCs and warn against the potential therapeutic applications of MSCs. Therefore, researchers should meticulously consider the biological properties of MSCs in preclinical and clinical studies to avoid any undesirable outcomes. This manuscript reviews preclinical studies on MSCs and cancer from the last two decades, discusses how MSC properties affect tumor progression and explains the mechanisms behind tumor suppressive and supportive functions. It also highlights critical cellular pathways that could be targeted in future studies to improve the safety and effectiveness of MSC-based therapies for cancer treatment. The insights obtained from this study will pave the way for further clinical research on MSCs and development of more effective cancer treatments.

DNA methylation drives a new path in gastric cancer early detection: Current impact and prospects

Gastric cancer (GC) is one of the most common and deadly cancers worldwide. Early detection offers the best chance for curative treatment and reducing its mortality. However, the optimal population-based early screening for GC remains unmet. Aberrant DNA methylation occurs in the early stage of GC, exhibiting cancer-specific genetic and epigenetic changes, and can be detected in the media such as blood, gastric juice, and feces, constituting a valuable biomarker for cancer early detection. Furthermore, DNA methylation is a stable epigenetic alteration, and many innovative methods have been developed to quantify it rapidly and accurately. Nonetheless, large-scale clinical validation of DNA methylation serving as tumor biomarkers is still lacking, precluding their implementation in clinical practice. In conclusion, after a critical analysis of the recent existing literature, we summarized the evolving roles of DNA methylation during GC occurrence, expounded the newly discovered noninvasive DNA methylation biomarkers for early detection of GC, and discussed its challenges and prospects in clinical applications.

Macrophage barrier in the tumor microenvironment and potential clinical applications

The tumor microenvironment (TME) constitutes a complex microenvironment comprising a diverse array of immune cells and stromal components. Within this intricate context, tumor-associated macrophages (TAMs) exhibit notable spatial heterogeneity. This heterogeneity contributes to various facets of tumor behavior, including immune response modulation, angiogenesis, tissue remodeling, and metastatic potential. This review summarizes the spatial distribution of macrophages in both the physiological environment and the TME. Moreover, this paper explores the intricate interactions between TAMs and diverse immune cell populations (T cells, dendritic cells, neutrophils, natural killer cells, and other immune cells) within the TME. These bidirectional exchanges form a complex network of immune interactions that influence tumor immune surveillance and evasion strategies. Investigating TAM heterogeneity and its intricate interactions with different immune cell populations offers potential avenues for therapeutic interventions. Additionally, this paper discusses therapeutic strategies targeting macrophages, aiming to uncover novel approaches for immunotherapy. Video Abstract.

Identification of neutrophil-related genes and development of a prognostic model for cholangiocarcinoma

BACKGROUND

Cholangiocarcinoma is a prevalent gastrointestinal tumor with limited effective early diagnostic methods. The role of neutrophils in the context of cholangiocarcinoma remains largely unexplored.

METHODS

A comprehensive analysis was performed on a cohort of cholangiocarcinoma samples (TCGA-CHOL) from the TCGA database to investigate the relationship between cholangiocarcinoma and neutrophils. Methodologies included single-sample gene set enrichment analysis (ssGSEA), differential expression analysis, weighted gene co-expression network analysis (WGCNA) and gene set enrichment analysis (GSEA).

RESULTS

The study identified a significant decrease of neutrophils in cholangiocarcinoma via ssGSEA. WGCNA and differential expression analysis led to the identification of a neutrophil-related gene module comprised of 1059 genes. Cluster 1, showing a higher proportion of neutrophils, was linked to better survival outcomes. GSEA disclosed downregulation of complement, inflammatory response and interferon response pathways in Cluster 2, hinting at possible cholangiocarcinoma development triggers. A notable upregulation of PD1, PD-L1 and CTLA4 was observed in Cluster 1, suggesting potential benefits from immunotherapy. A prognostic model was developed based on clinical data and expression levels of three prognostic genes (SOWAHD, TNFAIP8 and EBF3) showing satisfactory discrimination, calibration and clinical benefits. An overexpression of TNFAIP8 in cholangiocarcinoma cells was found, with its knockdown significantly inhibiting cell proliferation and migration.

CONCLUSIONS

This study elucidates a neutrophil-related gene module and prognostic genes, offering insights into the role of neutrophils in cholangiocarcinoma development and progression. It also introduces a clinical prediction model for enhanced prognosis assessment. These findings may lay the groundwork for the development of innovative therapeutic strategies in cholangiocarcinoma treatment.

Gastric tubular adenocarcinoma with diffuse neutrophils infiltrating: characteristics and probable treatment strategy

BACKGROUND

Gastric adenocarcinoma is a highly heterogeneous malignancy with varying prognoses. In clinicopathological practice, we noticed a special tubular adenocarcinoma with diffuse neutrophils infiltrating (TADNI). However, the proportion and characteristics of TADNI remain unclear. This study aimed to evaluate the features of TADNI and explore probable treatments.

METHODS

We divided 289 tubular adenocarcinoma cases into the TADNI and non-TADNI (nTADNI) groups by histological neutrophil quantity and performed immunohistochemistry of treatment-associated markers (CXCR1, CXCR2, PD-L1, CD8, HER2 and VEGFR2). Then we evaluated the clinical and morphological features in these cases. We also compared the value of histological features and peripheral blood neutrophil test. In addition, multiomics bioinformatic analyses were performed using the public datasets.

RESULTS

In our cohort, TADNI accounted for 10.4% of all tubular adenocarcinoma cases. These cases had worse prognoses (especially the neutrophils mainly outside the tubes) than nTADNI cases. The histological identification of TADNI had more prognostic value than peripheral blood neutrophils. CXCR1/CXCR2 expression was significantly high in TADNI group which indicated that CXCR1/CXCR2 inhibitors might be beneficial for TADNI patients. There were no significant differences in the expression of PD-L1, CD8, HER2 and VEGFR2. The analyses of TCGA data confirmed that TADNI cases had poorer prognoses and higher CXCR1/CXCR2 expression. Bioinformatic results also revealed molecular features (more hsa-mir-223 expression, fewer CD8-positive T cells and regulatory T cells, tighter communication between tumor cells' CXCR1/CXCR2 and neutrophils' CXCL5/CXCL8) of this type.

CONCLUSIONS

TADNI is a special morphological subtype with poorer prognoses and unique molecular characteristics, which might benefit from CXCR1/CXCR2 inhibitors.

Phenotypic and Functional Diversity of Neutrophils in Gut Inflammation and Cancer

Neutrophils [polymorphonuclear leukocytes (PMNs)] execute important effector functions protecting the host against invading pathogens. However, their activity in tissue can exacerbate inflammation and inflammation-associated tissue injury and tumorigenesis. Until recently, PMNs were considered to be short-lived, terminally differentiated phagocytes. However, this view is rapidly changing with the emerging evidence of increased PMN lifespan in tissues, PMN plasticity, and phenotypic heterogeneity. Specialized PMN subsets have been identified in inflammation and in developing tumors, consistent with both beneficial and detrimental functions of PMNs in these conditions. Because PMN and tumor-associated neutrophil activity and the resulting beneficial/detrimental impacts primarily occur after homing to inflamed tissue/tumors, studying the underlying mechanisms of PMN/tumor-associated neutrophil trafficking is of high interest and clinical relevance. This review summarizes some of the key findings from over a decade of work from my laboratory and others on the regulation of PMN recruitment and identification of phenotypically and functionally diverse PMN subtypes as they pertain to gut inflammation and colon cancer.

Mesenchymal stem/stromal cells- a principal element for tumour microenvironment heterogeneity

The heterogeneity of the tumor microenvironment (TME) is a major obstacle in cancer treatment, making most therapeutic interventions palliative rather than curative. Previous studies have suggested that the reason for the low efficacy of immunotherapy and the relapse of the original responders over time may be due to the complex network of mesenchymal stem/stromal cells (MSCs), a population of multipotent progenitor cells existing in a variety of tissues. Cancer-associated MSCs (CA-MSCs) have already been isolated from various types of tumors and are characterized by their vigorous pro-tumorigenic functions. Although the roles of CA-MSCs from different sources vary widely, their origins are still poorly understood. Current evidence suggests that when local resident or distally recruited MSCs interact with tumor cells and other components in the TME, "naïve" MSCs undergo genetic and functional changes to form CA-MSCs. In this review, we mainly focus on the multiple roles of CA-MSCs derived from different sources, which may help in elucidating the formation and function of the entire TME, as well as discover innovative targets for anti-cancer therapies.

Role of cancer-educated mesenchymal stromal cells on tumor progression

The malignant tumor is the main cause of human deaths worldwide. Current therapies focusing on the tumor itself have achieved unprecedented benefits. Various pro-tumorigenic factors in the tumor microenvironment (TME) could abolish the effect of cancer therapy. Mesenchymal stromal cells (MSCs) are one of the substantial components in the tumor microenvironment, contributing to tumor progression. However, MSCs are not inherently tumor-promoting. Indeed, they acquire pro-tumorigenic properties under the education of the TME. We herein review how various elements in the TME including tumor cells, immune cells, pro-inflammatory factors, hypoxia, and extracellular matrix influence the biological characteristics of MSCs through complex interactions and demonstrate the underlying mechanisms. We also highlight the importance of tumor-associated mesenchymal stromal cells (TA-MSCs) in promoting tumor progression. Our review gives a new insight into the TA-MSCs as a potential tumor therapeutic target. It is anticipated that subverting MSCs education will facilitate the outbreak of therapeutic strategies against tumors.

The Dual Role of Mesenchymal Stem Cells in Cancer Pathophysiology: Pro-Tumorigenic Effects versus Therapeutic Potential

Mesenchymal stem/stromal cells (MSCs) are multipotent cells involved in numerous physiological events, including organogenesis, the maintenance of tissue homeostasis, regeneration, or tissue repair. MSCs are increasingly recognized as playing a major, dual, and complex role in cancer pathophysiology through their ability to limit or promote tumor progression. Indeed, these cells are known to interact with the tumor microenvironment, modulate the behavior of tumor cells, influence their functions, and promote distant metastasis formation through the secretion of mediators, the regulation of cell-cell interactions, and the modulation of the immune response. This dynamic network can lead to the establishment of immunoprivileged tissue niches or the formation of new tumors through the proliferation/differentiation of MSCs into cancer-associated fibroblasts as well as cancer stem cells. However, MSCs exhibit also therapeutic effects including anti-tumor, anti-proliferative, anti-inflammatory, or anti-oxidative effects. The therapeutic interest in MSCs is currently growing, mainly due to their ability to selectively migrate and penetrate tumor sites, which would make them relevant as vectors for advanced therapies. Therefore, this review aims to provide an overview of the double-edged sword implications of MSCs in tumor processes. The therapeutic potential of MSCs will be reviewed in melanoma and lung cancers.

Neutrophil interactions with T cells, platelets, endothelial cells, and of course tumor cells

Neutrophils sense microbes and host inflammatory mediators, and traffic to sites of infection where they direct a broad armamentarium of antimicrobial products against pathogens. Neutrophils are also activated by damage-associated molecular patterns (DAMPs), which are products of cellular injury that stimulate the innate immune system through pathways that are similar to those activated by microbes. Neutrophils and platelets become activated by injury, and cluster and cross-signal to each other with the cumulative effect of driving antimicrobial defense and hemostasis. In addition, neutrophil extracellular traps are extracellular chromatin and granular constituents that are generated in response to microbial and damage motifs and are pro-thrombotic and injurious. Although neutrophils can worsen tissue injury, neutrophils may also have a role in facilitating wound repair following injury. A central theme of this review relates to how critical functions of neutrophils that evolved to respond to infection and damage modulate the tumor microenvironment (TME) in ways that can promote or limit tumor progression. Neutrophils are reprogrammed by the TME, and, in turn, can cross-signal to tumor cells and reshape the immune landscape of tumors. Importantly, promising new therapeutic strategies have been developed to target neutrophil recruitment and function to make cancer immunotherapy more effective.

The Role of Mesenchymal Stem Cells in Modulating the Breast Cancer Microenvironment

The role of mesenchymal stem cells (MSCs) in the breast tumor microenvironment (TME) is significant and multifaceted. MSCs are recruited to breast tumor sites through molecular signals released by tumor sites. Once in the TME, MSCs undergo polarization and interact with various cell populations, including immune cells, cancer-associated fibroblasts (CAFs), cancer stem cells (CSCs), and breast cancer cells. In most cases, MSCs play roles in breast cancer therapeutic resistance, but there is also evidence that indicates their abilities to sensitize cancer cells to chemotherapy and radiotherapy. MSCs possess inherent regenerative and homing properties, making them attractive candidates for cell-based therapies. Therefore, MSCs can be engineered to express therapeutic molecules or deliver anti-cancer agents directly to tumor sites. Unraveling the intricate relationship between MSCs and the breast TME has the potential to uncover novel therapeutic targets and advance our understanding of breast cancer biology.

Effect of NETs/COX-2 pathway on immune microenvironment and metastasis in gastric cancer

Background

Neutrophil extracellular traps (NETs) are crucial in the progression of several cancers. The formation of NETs is closely related to reactive oxygen species (ROS), and the granule proteins involved in nucleosome depolymerization under the action of ROS together with the loosened DNA compose the basic structure of NETs. This study aims to investigate the specific mechanisms of NETs promoting gastric cancer metastasis in order to perfect the existing immunotherapy strategies.

Methods

In this study, the cells and tumor tissues of gastric cancer were detected by immunological experiments, real-time polymerase chain reaction and cytology experiments. Besides, bioinformatics analysis was used to analyze the correlation between cyclooxygenase-2 (COX-2) and the immune microenvironment of gastric cancer, as well as its effect on immunotherapy.

Results

Examination of clinical specimens showed that NETs were deposited in tumor tissues of patients with gastric cancer and their expression was significantly correlated with tumor staging. Bioinformatics analysis showed that COX-2 was involved in gastric cancer progression and was associated with immune cell infiltration as well as immunotherapy. In vitro experiments, we demonstrated that NETs could activate COX-2 through Toll-like receptor 2 (TLR2) and thus enhance the metastatic ability of gastric cancer cells. In addition, in a liver metastasis model of nude mice we also demonstrated the critical role of NETs and COX-2 in the distant metastasis of gastric cancer.

Conclusion

NETs can promote gastric cancer metastasis by initiating COX-2 through TLR2, and COX-2 may become a target for gastric cancer immunotherapy.

Signaling pathways in cancer-associated fibroblasts: recent advances and future perspectives

As a critical component of the tumor microenvironment (TME), cancer-associated fibroblasts (CAFs) play important roles in cancer initiation and progression. Well-known signaling pathways, including the transforming growth factor-β (TGF-β), Hedgehog (Hh), Notch, Wnt, Hippo, nuclear factor kappa-B (NF-κB), Janus kinase (JAK)/signal transducer and activator of transcription (STAT), mitogen-activated protein kinase (MAPK), and phosphoinositide 3-kinase (PI3K)/AKT pathways, as well as transcription factors, including hypoxia-inducible factor (HIF), heat shock transcription factor 1 (HSF1), P53, Snail, and Twist, constitute complex regulatory networks in the TME to modulate the formation, activation, heterogeneity, metabolic characteristics and malignant phenotype of CAFs. Activated CAFs remodel the TME and influence the malignant biological processes of cancer cells by altering the transcriptional and secretory characteristics, and this modulation partially depends on the regulation of signaling cascades. The results of preclinical and clinical trials indicated that therapies targeting signaling pathways in CAFs demonstrated promising efficacy but were also accompanied by some failures (e.g., NCT01130142 and NCT01064622). Hence, a comprehensive understanding of the signaling cascades in CAFs might help us better understand the roles of CAFs and the TME in cancer progression and may facilitate the development of more efficient and safer stroma-targeted cancer therapies. Here, we review recent advances in studies of signaling pathways in CAFs and briefly discuss some future perspectives on CAF research.

MSCs can be a double-edged sword in tumorigenesis

Mesenchymal stem cells (MSCs) have been used to treat various diseases including Alzheimer's disease and cancer. In particular, the immunomodulatory function of MSCs plays a major role in cancer therapy using stem cells. However, MSCs exert promotive and inhibitory effects on cancer. The immunomodulatory effects of MSCs in the tumor microenvironment (TME) are ambiguous, which is the primary reason for the different outcomes of MSCs therapies for tumors. This review discusses the use of MSCs in cancer immunotherapy and their immunomodulatory mechanisms in cancers.

Tumor microenvironment-mediated immune tolerance in development and treatment of gastric cancer

Tumor microenvironment is the general term for all non-cancer components and their metabolites in tumor tissue. These components include the extracellular matrix, fibroblasts, immune cells, and endothelial cells. In the early stages of tumors, the tumor microenvironment has a tumor suppressor function. As the tumor progresses, tumor immune tolerance is induced under the action of various factors, such that the tumor suppressor microenvironment is continuously transformed into a tumor-promoting microenvironment, which promotes tumor immune escape. Eventually, tumor cells manifest the characteristics of malignant proliferation, invasion, metastasis, and drug resistance. In recent years, stress effects of the extracellular matrix, metabolic and phenotypic changes of innate immune cells (such as neutrophils, mast cells), and adaptive immune cells in the tumor microenvironment have been revealed to mediate the emerging mechanisms of immune tolerance, providing us with a large number of emerging therapeutic targets to relieve tumor immune tolerance. Gastric cancer is one of the most common digestive tract malignancies worldwide, whose mortality rate remains high. According to latest guidelines, the first-line chemotherapy of advanced gastric cancer is the traditional platinum and fluorouracil therapy, while immunotherapy for gastric cancer is extremely limited, including only Human epidermal growth factor receptor 2 (HER-2) and programmed death ligand 1 (PD-L1) targeted drugs, whose benefits are limited. Clinical experiments confirmed that cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), vascular endothelial growth factor receptor (VEGFR) and other targeted drugs alone or in combination with other drugs have limited efficacy in patients with advanced gastric cancer, far less than in lung cancer, colon cancer, and other tumors. The failure of immunotherapy is mainly related to the induction of immune tolerance in the tumor microenvironment of gastric cancer. Therefore, solving the immune tolerance of tumors is key to the success of gastric cancer immunotherapy. In this study, we summarize the latest mechanisms of various components of the tumor microenvironment in gastric cancer for inducing immune tolerance and promoting the formation of the malignant phenotype of gastric cancer, as well as the research progress of targeting the tumor microenvironment to overcome immune tolerance in the treatment of gastric cancer.

Tumor-Associated Neutrophils in Colorectal Cancer Development, Progression and Immunotherapy

The colorectal-cancer (CRC) incidence rate and mortality have remained high for several years. In recent years, immune-checkpoint-inhibitor (ICI) therapy has rapidly developed. However, it is only effective in a few CRC patients with microsatellite-instability-high (MSI-H) or mismatch-repair-deficient (dMMR) CRC. How to improve the efficiency of ICI therapy in CRC patients with microsatellite stability (MSS) remains a huge obstacle. Tumor-associated neutrophils (TANs), which are similar to macrophages, also have N1 and N2 phenotypes. They can be recruited and polarized through different cytokines or chemokines, and then play an antitumor or tumor-promoting role. In CRC, we find that the prognostic significance of TANs is still controversial. In this review, we describe the antitumor regulation of TANs, and their mechanism of promoting tumor progression by boosting the transformation of inflammation into tumors, facilitating tumor-cell proliferation, metastasis and angiogenesis. The targeting of TANs combined with ICIs may be a new treatment model for CRC. Relevant animal experiments have shown good responses, and clinical trials have also been carried out in succession. TANs, as “assistants” of ICI treatment, may become the key to the success of CRC immunotherapy, although no significant results have been obtained.

Exosomes From Cancer-Associated Mesenchymal Stem Cells Transmit TMBIM6 to Promote the Malignant Behavior of Hepatocellular Carcinoma via Activating PI3K/AKT Pathway

Objective

Cancer-associated mesenchymal stem cells (MSCs) regulate the progression of cancers through exosome-delivered components, while few studies are conducted on hepatocellular carcinoma (HCC). This study aimed to evaluate the effect of exosomes from HCC-associated MSCs (HCC-MSCs) on HCC cellular functions and the potential regulatory mechanism.

Methods

HCC cells (Huh7 and PLC) were cultured normally or co-cultured with HCC-MSCs, HCC-MSCs plus GW4869, or HCC-MSC-derived exosomes; then mRNA sequencing and RT-qPCR validation were conducted. Subsequently, candidate genes were sorted out and modified in HCC cells. Next, TMBIM6-modified HCC-MSCs were used to treat HCC cells.

Results

Both HCC-MSCs and their derived exosomes promoted proliferation, invasion, sphere formation ability but suppressed apoptosis in HCC cells (all p < 0.05); however, the effect of HCC-MSCs on these cellular functions was repressed by exosome inhibitor (GW4869). Subsequently, TMBIM6, EEF2, and PRDX1 were sorted out by mRNA sequencing and RT-qPCR validation as candidate genes implicated in the regulation of HCC cellular functions by HCC-MSC-derived exosomes. Among them, TMBIM6 had a potent effect (all p < 0.05), while EEF2 and PRDX1 had less effect on regulating HCC cell viability and invasion. Next, direct silencing TMBIM6 repressed viability, sphere formation, invasion, epithelial-mesenchymal transition (EMT), and PI3K/AKT pathway but promoted apoptosis in HCC cells; however, overexpressing TMBIM6 showed the opposite effect. Furthermore, incubating with exosomes from TMBIM6-modified HCC-MSCs presented a similar effect as direct TMBIM6 modification in HCC cells.

Conclusion

HCC-MSC-derived exosomes transmit TMBIM6 to promote malignant behavior via PI3K/AKT pathway in HCC.

Immunobiology of cancer-associated fibroblasts in the context of radiotherapy

Radiotherapy (RT) still represents a mainstay of treatment in clinical oncology. Traditionally, the effectiveness of radiotherapy has been attributed to the killing potential of ionizing radiation (IR) over malignant cells, however, it has become clear that therapeutic efficacy of RT also involves activation of innate and adaptive anti-tumor immune responses. Therapeutic irradiation of the tumor microenvironment (TME) provokes profound cellular and biological reconfigurations which ultimately may influence immune recognition. As one of the major constituents of the TME, cancer-associated fibroblasts (CAFs) play central roles in cancer development at all stages and are recognized contributors of tumor immune evasion. While some studies argue that RT affects CAFs negatively through growth arrest and impaired motility, others claim that exposure of fibroblasts to RT promotes their conversion into a more activated phenotype. Nevertheless, despite the well-described immunoregulatory functions assigned to CAFs, little is known about the interplay between CAFs and immune cells in the context of RT. In this review, we go over current literature on the effects of radiation on CAFs and the influence that CAFs have on radiotherapy outcomes, and we summarize present knowledge on the transformed cellular crosstalk between CAFs and immune cells after radiation.

Leveling Up the Controversial Role of Neutrophils in Cancer: When the Complexity Becomes Entangled

Neutrophils are the most abundant immune cell in the circulation of human and act as gatekeepers to discard foreign elements that have entered the body. They are essential in initiating immune responses for eliminating invaders, such as microorganisms and alien particles, as well as to act as immune surveyors of cancer cells, especially during the initial stages of carcinogenesis and for eliminating single metastatic cells in the circulation and in the premetastatic organs. Since neutrophils can secrete a whole range of factors stored in their many granules as well as produce reactive oxygen and nitrogen species upon stimulation, neutrophils may directly or indirectly affect carcinogenesis in both the positive and negative directions. An intricate crosstalk between tumor cells, neutrophils, other immune cells and stromal cells in the microenvironment modulates neutrophil function resulting in both anti- and pro-tumor activities. Both the anti-tumor and pro-tumor activities require chemoattraction towards the tumor cells, neutrophil activation and ROS production. Divergence is seen in other neutrophil properties, including differential secretory repertoire and membrane receptor display. Many of the direct effects of neutrophils on tumor growth and metastases are dependent on tight neutrophil–tumor cell interactions. Among them, the neutrophil Mac-1 interaction with tumor ICAM-1 and the neutrophil L-selectin interaction with tumor-cell sialomucins were found to be involved in the neutrophil-mediated capturing of circulating tumor cells resulting in increased metastatic seeding. On the other hand, the anti-tumor function of neutrophils was found to rely on the interaction between tumor-surface-expressed receptor for advanced glycation end products (RAGE) and Cathepsin G expressed on the neutrophil surface. Intriguingly, these two molecules are also involved in the promotion of tumor growth and metastases. RAGE is upregulated during early inflammation-induced carcinogenesis and was found to be important for sustaining tumor growth and homing at metastatic sites. Cathepsin G was found to be essential for neutrophil-supported lung colonization of cancer cells. These data level up the complexity of the dual role of neutrophils in cancer.

The Origins and Generation of Cancer-Associated Mesenchymal Stromal Cells: An Innovative Therapeutic Target for Solid Tumors

Cancer-associated mesenchymal stromal cells (CA-MSCs) have been isolated from various types of tumors and are characterized by their vigorous pro-tumorigenic functions. However, very little is known about the origins and generating process of CA-MSCs, which may facilitate the identification of biomarkers for diagnosis or innovative targets for anti-cancer therapy to restrain the tumor growth, spread and chemotherapy resistance. Current evidences have indicated that both distally recruited and local resident MSCs are the primary origins of CA-MSCs. In a tissue type-dependent mode, tumor cells together with the TME components prompt the malignant transition of tumor “naïve” MSCs into CA-MSCs in a direct cell-to-cell contact, paracrine or exosome-mediated manner. In this review, we discuss the transition of phenotypes and functions of naïve MSCs into CA-MSCs influenced by tumor cells or non-tumor cells in the TME. The key areas remaining poorly understood are also highlighted and concluded herein.

Dynamic stromal cellular reaction throughout human colorectal adenoma-carcinoma sequence: A role of TH17/IL-17A

BACKGROUND

Accumulating data suggest that the tumour stroma rapidly undergoes dynamic mechanical and cellular changes by which creates a supportive milieu to promote disease progression and metastasis. Cytokines are reported to play a key role in the modulation of tumour stromal response.

METHODS

The activation of TH17/interleukin (IL)-17A network in association with tumour stromal proliferative and cellular response in samples from 50 patients with colorectal adenoma, 45 with colorectal cancer (CRCs) were elucidated with quantitative real-time PCR (q-PCR), immunohistochemistry and double immunofluorescence.

RESULTS

q-PCR results showed that retinoic acid-receptor-related orphan receptor-C, a critical transcriptional factor for TH17 cell differentiation, was significantly increased at the adenoma stage and slightly decreased at the CRC stage, but was still higher than that at normal controls. The level of TH17 signature cytokine IL-17A was shown in an increasing gradient throughout the adenoma-carcinoma sequence. Immunohistochemistry revealed an activated proliferative rate evaluated by Ki67 and population expansion of myofibroblasts in the adenoma/CRC stroma. Notably, densities of IL-17A-expressing cells were associated with populations of Ki67-positive cells and myofibroblasts in the adenoma/CRC stroma. Finally, CD146-positive stromal cells are an important participator for stroma remodelling, double immunofluorescence image demonstrated that IL-17 receptor C, one of the key elements for IL-17 receptor complex, was highly expressed in CD146-positive adenoma/CRC stromal cells.

CONCLUSIONS

An activated TH17/IL-17A network in the tumour microenvironment is significantly associated with dynamic stromal cellular response throughout the adenoma-carcinoma sequence, which might provide a supportive environment for the initiation and progression of CRC.

IL-12 Family Cytokines in Cancer and Immunotherapy

The IL-12 family cytokines are a group of unique heterodimeric cytokines that include IL-12, IL-23, IL-27, IL-35 and, most recently, IL-39. Recent studies have solidified the importance of IL-12 cytokines in shaping innate and adaptive immune responses in cancer and identified multipronged roles for distinct IL-12 family members, ranging from effector to regulatory immune functions. These cytokines could serve as promising candidates for the development of immunomodulatory therapeutic approaches. Overall, IL-12 can be considered an effector cytokine and has been found to engage anti-tumor immunity by activating the effector Th1 response, which is required for the activation of cytotoxic T and NK cells and tumor clearance. IL-23 and IL-27 play dual roles in tumor immunity, as they can both activate effector immune responses and promote tumor growth by favoring immune suppression. IL-35 is a potent regulatory cytokine and plays a largely pro-tumorigenic role by inhibiting effector T cells. In this review, we summarize the recent findings on IL-12 family cytokines in the control of tumor growth with an emphasis primarily on immune regulation. We underscore the clinical implications for the use of these cytokines either in the setting of monotherapy or in combination with other conventional therapies for the more effective treatment of malignancies.

Cancer-associated fibroblasts and their influence on tumor immunity and immunotherapy

Fibroblasts play an essential role in organogenesis and the integrity of tissue architecture and function. Growth in most solid tumors is dependent upon remodeling 'stroma', composed of cancer-associated fibroblasts (CAFs) and extracellular matrix (ECM), which plays a critical role in tumor initiation, progression, metastasis, and therapeutic resistance. Recent studies have clearly established that the potent immunosuppressive activity of stroma is a major mechanism by which stroma can promote tumor progression and confer resistance to immune-based therapies. Herein, we review recent advances in identifying the stroma-dependent mechanisms that regulate cancer-associated inflammation and antitumor immunity, in particular, the interactions between fibroblasts and immune cells. We also review the potential mechanisms by which stroma can confer resistance to immune-based therapies for solid tumors and current advancements in stroma-targeted therapies.

Crosstalk Between Mesenchymal Stromal Cells and Tumor-Associated Macrophages in Gastric Cancer

Tumor microenvironment (TME) consisting of distinct cell types including stromal cells and immune cells has recently emerged as a pivotal player in tumor development and progression. Mesenchymal stromal cells (MSCs) and tumor-associated macrophages (TAMs) are two representative cells in the TME with plastic properties. This review will focus on the evolution of phenotypes and functions of either MSCs or TAMs, which is “educated” by the TME, as well as interactions between MSCs and TAMs contributing to the distinct stages of tumor biology in gastric cancer. MSCs exert immunoregulatory effects on macrophages and polarize them toward M2-like TAMs, via cell–cell contact and paracrine or extracellular vesicle (EV) transfer mechanism. In turn, M2-TAMs modulate the transition of “naive” MSCs into tumor-derived MSCs, which possess a more potent pro-tumor role than the parent. Moreover, the cross talk between MSCs and TAMs could contribute to cancer biology by inducing the EMT process, metastasis, immune invasion, and immunotherapy resistance in cancer cells. However, molecular mechanisms underlying interactions between MSCs and TAMs in gastric cancer progression need to be thoroughly elucidated, which may provide attractive targets for making promising novel strategies for gastric cancer therapy.