A review of tanshinone compounds in prostate cancer treatment.

Prostate cancer (PCa) is one of the most common malignant epithelial tumors in men worldwide. PCa patients are initially sensitive to chemotherapy, but patients in the advanced stages of PCa eventually develop resistance, leaving them with limited therapeutic options. Therefore, it is very important to screen new drugs for treating PCa. Salvia miltiorrhiza is a common Chinese herbal medicine used in some Asian countries. It has many functions and is widely used to treat a variety of diseases, including heart diseases and cancers. For the past few years, research has shown that liposoluble constituents of tanshinones (TANs), including cryptotanshinone, TAN IIA, dihydrotanshinone I, and TAN I, exhibit good anticancer activity in PCa. In this study, we review the progress of TAN compounds (cryptotanshinone, TAN IIA, dihydrotanshinone I, and TAN I) in treating PCa over the past decade. These compounds can act on the same molecular mechanisms, as they have a very similar structure; they are also found to work slightly differently in PCa. According to current studies, compared with other TAN compounds, TAN IIA appears to hold more potential for treating PCa. The toxicity, side effects or biodistribution of Salvia miltiorrhiza and these four TANs need to be confirmed with further research. Findings obtained in this study may provide important information for the potential clinical application of cryptotanshinone, TAN IIA, dihydrotanshinone I, and TAN I in the treatment of PCa.

Neutrophils as promising therapeutic targets in pancreatic cancer liver metastasis.

Pancreatic cancer is characterized by an extremely poor prognosis and presents significant treatment challenges. Liver metastasis is the leading cause of death in patients with pancreatic cancer. Recent studies have highlighted the significant impact of neutrophils on tumor occurrence and progression, as well as their crucial role in the pancreatic cancer tumor microenvironment. Neutrophil infiltration plays a critical role in the progression and prognosis of pancreatic cancer. Neutrophils contribute to pancreatic cancer liver metastasis through various mechanisms, including angiogenesis, immune suppression, immune evasion, and epithelial-mesenchymal transition (EMT). Therefore, targeting neutrophils holds promise as an important therapeutic strategy for inhibiting pancreatic cancer liver metastasis. This article provides a summary of research findings on the involvement of neutrophils in pancreatic cancer liver metastasis and analyzes their potential as therapeutic targets. This research may provide new insights for the treatment of pancreatic cancer and improve the prognosis of patients with this disease.

High peripheral neutrophil and monocyte count distinguishes renal cell carcinoma from renal angiomyolipoma and predicts poor prognosis of renal cell carcinoma.

Background: The presence of peripheral inflammatory cells has been linked to the prognosis of cancer. This study aims to investigate the distinct roles of absolute neutrophil count (ANC) and absolute monocyte count (AMC) in differentiating renal cell carcinoma (RCC) from renal angiomyolipoma (RAML), as well as their prognostic significance in RCC. Methods: We conducted a comprehensive analysis of peripheral immune cell data, clinicopathological data, and tumor characteristics in patients diagnosed with RCC or RAML from January 2015 to December 2021. Receiver operating characteristic (ROC) curves, as well as univariate and multivariate analyses, were employed to assess the diagnostic utility of AMC and ANC in differentiating between RCC and RAML. Kaplan-Meier curve analysis was used to study the survival of RCC patients with different AMC and ANC. The prognostic value of AMC and ANC in RCC was investigated using COX univariate and multivariate analysis. The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases were used for bioinformatic correlation analysis. Results: A total of 1120 eligible patients were included in the study. The mean preoperative AMC and ANC in patients with RCC were found to be significantly higher compared to those in patients with RAML (P = 0.001 and P < 0.001, respectively). High preoperative AMC and ANC significantly correlated with smoking history, tumor length, gross hematuria, and high T Stage, N stage, and pathological grade. In multivariate analyses, an ANC> 3.205 *10^9/L was identified to be independently associated with the presence of RCC (HR = 1.618, P = 0.008). High AMC and ANC were significantly associated with reduced OS and PFS (P < 0.05), and ANC may be an independent prognostic factor. Public database analysis showed that signature genes of tumor-associated macrophages (TAMs) and tumor-associated neutrophils (TANs) were highly expressed in ccRCC. Conclusions: Elevated preoperative ANC and AMC can distinguish RCC from RAML and predict poor prognosis in patients with RCC. Furthermore, the signature genes of TAMs and TANs exhibit high expression levels in clear cell RCC.

Non-Tumor Cells within the Tumor Microenvironment-The "Eminence Grise" of the Glioblastoma Pathogenesis and Potential Targets for Therapy.

Glioblastoma (GBM) is the most common malignancy of the central nervous system in adults. GBM has high levels of therapy failure and its prognosis is usually dismal. The phenotypic heterogeneity of the tumor cells, dynamic complexity of non-tumor cell populations within the GBM tumor microenvironment (TME), and their bi-directional cross-talk contribute to the challenges of current therapeutic approaches. Herein, we discuss the etiology of GBM, and describe several major types of non-tumor cells within its TME, their impact on GBM pathogenesis, and molecular mechanisms of such an impact. We also discuss their value as potential therapeutic targets or prognostic biomarkers, with reference to the most recent works on this subject. We conclude that unless all "key player" populations of non-tumor cells within the TME are considered, no breakthrough in developing treatment for GBM can be achieved.

How murine neutrophils are hijacked within the microenvironment of pancreatic cancer.

Discoveries made in the past decades have brought out that, in addition to their classical primary defensive functions against infections, polymorphonuclear neutrophils play key effector roles not only in chronic inflammatory and immune-mediated diseases but also in cancer. In addition, depending on their differentiation/activation status and/or on the physiological or pathological microenvironment in which they reside, neutrophils have been shown to behave as highly plastic cells, able to acquire new phenotypes/functional states. All these features are well manifested in cancer and modulated during tumor progression. Herein, we discuss intriguing data by Lai Ng's group that have shed light on the origin and development of terminally differentiated, proangiogenic, tumor-associated neutrophils, facilitating tumor growth in a murine orthotopic model of pancreatic ductal adenocarcinoma. These findings help to progress toward the ambitious goal of selectively targeting only the skewed pathological neutrophil populations present within the tumor microenvironment.

The evolution and heterogeneity of neutrophils in cancers: origins, subsets, functions, orchestrations and clinical applications.

Neutrophils, the most prevalent innate immune cells in humans, have garnered significant attention in recent years due to their involvement in cancer progression. This comprehensive review aimed to elucidate the important roles and underlying mechanisms of neutrophils in cancer from the perspective of their whole life cycle, tracking them from development in the bone marrow to circulation and finally to the tumor microenvironment (TME). Based on an understanding of their heterogeneity, we described the relationship between abnormal neutrophils and clinical manifestations in cancer. Specifically, we explored the function, origin, and polarization of neutrophils within the TME. Furthermore, we also undertook an extensive analysis of the intricate relationship between neutrophils and clinical management, including neutrophil-based clinical treatment strategies. In conclusion, we firmly assert that directing future research endeavors towards comprehending the remarkable heterogeneity exhibited by neutrophils is of paramount importance.

CD39 inhibition and VISTA blockade may overcome radiotherapy resistance by targeting exhausted CD8+ T cells and immunosuppressive myeloid cells.

Although radiotherapy (RT) has achieved great success in the treatment of non-small cell lung cancer (NSCLC), local relapses still occur and abscopal effects are rarely seen even when it is combined with immune checkpoint blockers (ICBs). Here, we characterize the dynamic changes of tumor-infiltrating immune cells after RT in a therapy-resistant murine tumor model using single-cell transcriptomes and T cell receptor sequencing. At the early stage, the innate and adaptive immune systems are activated. At the late stage, however, the tumor immune microenvironment (TIME) shifts into immunosuppressive properties. Our study reveals that inhibition of CD39 combined with RT preferentially decreases the percentage of exhausted CD8+ T cells. Moreover, we find that the combination of V-domain immunoglobulin suppressor of T cell activation (VISTA) blockade and RT synergistically reduces immunosuppressive myeloid cells. Clinically, high VISTA expression is associated with poor prognosis in patients with NSCLC. Altogether, our data provide deep insight into acquired resistance to RT from an immune perspective and present rational combination strategies.

Prognostic analysis and validation of lncRNAs in bladder cancer on the basis of neutrophil extracellular traps.

BACKGROUND: Complex interactions in the tumor microenvironment (TME) between bladder cancer (BLCA) and immune cells are critical for cancer progression. However, studies of neutrophil extracellular trap-associated long non-coding RNAs (NET-lncRNAs) in the TME of BLCA have not been reported. This study aims to screen for NET-lncRNAs in BLCA and to preliminarily explore their effects on BLCA development. METHODS: The correlation of NET-related gene sets, which were identified from the cancer genome atlas (TCGA) BLCA datasets, with lncRNAs was analyzed and the prognosis-related genes were identified through random forest analysis. The least absolute shrinkage and selection operator (LASSO) model was utilized to obtain prognostic risk scores for NET-lncRNAs (NET-Score). We collected clinical BLCA samples, as well as SV-HUC-1 and BLCA cells, to validate the expression of NET-lncRNAs. Survival and independent prognostic analysis were performed. In J82 and UM-UC-3 cells, after NKILA expression was inhibited, cell proliferation and apoptosis levels were detected. RESULTS: NET-related gene sets mainly included CREB5, MMP9, PADI4, CRISPLD2, CD93, DYSF, MAPK3, TECPR2, MAPK1 and PIK3CA. Then, four NET-lncRNAs, MAP 3 K4-AS1, MIR100HG, NKILA and THY1-AS1, were identified. NET-Score had the highest hazard ratio for BLCA. An elevated NET-Score was linked to a significant increase in immune cell infiltration and copy number variation, as well as a notable decrease in survival rate and drug sensitivity. NET-lncRNA-related genes were mainly enriched in the pathways of angiogenesis, immune response, cell cycle and T cell activation. MAP 3 K4-AS1, MIR100HG, NKILA and THY1-AS1 expressions were significantly increased in BLCA tissues. Compared with SV-HUC-1 cells, NKILA expression was elevated in J82 and UM-UC-3 cells. Inhibition of NKILA expression inhibited the proliferation and promoted apoptosis of J82 and UM-UC-3 cells. CONCLUSIONS: Several NET-lncRNAs, including MAP 3 K4-AS1, MIR100HG, NKILA and THY1-AS1, were successfully screened in the BLCA. The NET-Score was an independent prognostic factor for BLCA. In addition, inhibition of NKILA expression suppressed BLCA cell development. The above NET-lncRNAs could serve as potential prognostic markers and targets in BLCA.

The effect of amputation level on patient mental and psychological health, prospective observational cohort study.

Background: Non-traumatic lower limb amputation is a commonly performed surgical procedure and is associated with a high prevalence of psychological morbidity including anxiety and depression. Many risk factors have been identified, including the indication for amputation, perioperative pain and sociodemographic factors. Objective: The aim of this study was to identify whether level of amputation has an impact on this psychological morbidity. Methods: A prospective observational study was conducted in a tertiary vascular unit including all adult non-traumatic amputations performed during a 6 month period. The Hospital Anxiety and Depression Scale (HADS) was used to score anxiety and depression pre and postoperatively. Results: 49 patients met the inclusion criteria (22 trans-femoral amputations (AKA) and 27 trans-tibial amputations (BKA)). HADS scores for anxiety and depression were high in both groups both pre and postoperatively. A higher level of anxiety was noted in the BKA group, significantly decreasing postoperatively (p < 0.05). No other statistically significant differences were found between the two groups. Conclusion: In non-traumatic amputations, there appears to be a higher rate of pre-operative anxiety in patients undergoing trans-tibial amputation compared with trans-femoral amputees. However, the level of amputation does not appear to have a significant effect on psychological status of patients with high rates of depression and anxiety demonstrated in both groups.

Targeting the Tumor Microenvironment: A Close Up of Tumor-Associated Macrophages and Neutrophils.

The importance of the tumor microenvironment (TME) in dynamically regulating cancer progression and influencing the therapeutic outcome is widely accepted and appreciated. Several therapeutic strategies to modify or modulate the TME, like angiogenesis or immune checkpoint inhibitors, showed clinical efficacy and received approval from regulatory authorities. Within recent decades, new promising strategies targeting myeloid cells have been implemented in preclinical cancer models. The predominance of specific cell phenotypes in the TME has been attributed to pro- or anti-tumoral. Hence, their modulation can, in turn, alter the responses to standard-of-care treatments, making them more or less effective. Here, we summarize and discuss the current knowledge and the correlated challenges about the tumor-associated macrophages and neutrophils targeting strategies, current treatments, and future developments.

Feiyanning downregulating CXCLs/CXCR2 axis to suppress TANs infiltration in the prevention of lung cancer metastasis.

ETHNOPHARMACOLOGICAL RELEVANCE: Tumor-associated neutrophils (TANs) play an important role in tumor metastasis. The Traditional Chinese medicine (TCM) Feiyanning (FYN) has been clinically proven to effectively prevent the recurrence and metastasis of lung cancer, improve immunity, and prolong the survival period of lung cancer patients. However, its anti-metastatic immune mechanism has not been fully elucidated. To this end, we studied the mechanism of FYN's regulation of neutrophils infiltration in the tumor microenvironment (TME). AIM OF THE STUDY: To explore the anti-metastatic mechanism of FYN from the perspective of anti-immunosuppressive phenotype neutrophils infiltration in the TME. MATERIALS AND METHODS: TCM network pharmacological analysis was used to predict Feiyanning effective target. Flow cytometry was used to detect the proportion of immune cell subsets in the TME. Lung metastases were investigated in C57 mice by tail vein injection. Protein expression was evaluated by immunohistochemistry and Western blot. Gene expression was evaluated by qRT-PCR. RESULTS: FYN could reshape the tumor immune microenvironment. It prevents Tregs, M2 macrophages, and neutrophils infiltration, as well as recruits T cells, NK cells, and DCs, and improves DCs activation. In addition, FYN could regulate the polarization of TANs, inhibit the infiltration of neutrophils with an immunosuppressive phenotype, downregulate CXCLs/CXCR2 axis and inhibitory factors like Arg-1 and TGF-ß, and up-regulate the immune effector molecule ICAM-1. Furthermore, FYN increases anti-tumor immune effects in the TME to prevent tumor cells from spreading to the lungs. CONCLUSION: This study clarifies the potential mechanism of FYN in regulating neutrophils infiltration and anti-metastasis. FYN may regulate neutrophils infiltration in the TME by regulating CXCLs/CXCR2 axis.

Oxidative Stress and Cancer Heterogeneity Orchestrate NRF2 Roles Relevant for Therapy Response.

Oxidative stress and its end-products, such as 4-hydroxynonenal (HNE), initiate activation of the Nuclear Factor Erythroid 2-Related Factor 2 (NRF2)/Kelch Like ECH Associated Protein 1 (KEAP1) signaling pathway that plays a crucial role in the maintenance of cellular redox homeostasis. However, an involvement of 4-HNE and NRF2 in processes associated with the initiation of cancer, its progression, and response to therapy includes numerous, highly complex events. They occur through interactions between cancer and stromal cells. These events are dependent on many cell-type specific features. They start with the extent of NRF2 binding to its cytoplasmic repressor, KEAP1, and extend to the permissiveness of chromatin for transcription of Antioxidant Response Element (ARE)-containing genes that are NRF2 targets. This review will explore epigenetic molecular mechanisms of NRF2 transcription through the specific molecular anatomy of its promoter. It will explain the role of NRF2 in cancer stem cells, with respect to cancer therapy resistance. Additionally, it also discusses NRF2 involvement at the cross-roads of communication between tumor associated inflammatory and stromal cells, which is also an important factor involved in the response to therapy.

CXCR2 Mediates Distinct Neutrophil Behavior in Brain Metastatic Breast Tumor.

Brain metastasis is one of the main causes of mortality among breast cancer patients, but the origins and the mechanisms that drive this process remain poorly understood. Here, we report that the upregulation of certain CXCR2-associated ligands in the brain metastatic variants of the breast cancer cells (BrM) dynamically activate the corresponding CXCR2 receptors on the neutrophils, thereby resulting in the modulation of certain key functional neutrophil responses towards the BrM. Using established neutrophil-tumor biomimetic co-culture models, we show that the upregulation of CXCR2 increases the recruitment of Tumor-Associated Neutrophils (TANs) towards the BrM, to enable location-favored formation of Neutrophil Extracellular Traps (NETs). Inhibition of CXCR2 using small molecule antagonist AZD5069 reversed this behavior, limiting the neutrophil responses to the BrM and retarding the reciprocal tumor development. We further demonstrate that abrogation of NETs formation using Neutrophil Elastase Inhibitor (NEI) significantly decreases the influx of neutrophils towards BrM but not to their parental tumor, suggesting that CXCR2 activation could be used by the brain metastatic tumors as a mechanism to program the tumor-infiltrating TANs into a pro-NETotic state, so as to assume a unique spatial distribution that assists in the subsequent migration and invasion of the metastatic tumor cells. This new perspective indicates that CXCR2 is a critical target for suppressing neutrophilic inflammation in brain metastasis.

Tumor-Infiltrating PD-L1+ Neutrophils Induced by GM-CSF Suppress T Cell Function in Laryngeal Squamous Cell Carcinoma and Predict Unfavorable Prognosis.

PURPOSE: Chronic inflammation contributes to tumor initiation, progression, and immune escape. Neutrophils are the major component of inflammatory response and participate in the tumorigenesis process. However, compared to other immune cells in the tumor microenvironment of laryngeal squamous cell carcinoma (LSCC), neutrophils, especially the tumor-associated neutrophils (TANs), have not yet been comprehensively explored. The mechanism for regulating the crosstalk between TANs and tumor cells still remains unclear. MATERIALS AND METHODS: The distribution profiles and phenotypic features of neutrophils and other inflammatory immune cell populations from a large LSCC patient cohort were systemically analyzed. Co-culturing of peripheral blood associated neutrophils (PANs) and TANs with PBMCs was performed, and the immunosuppression effect on T-cells was examined. RESULTS: LSCC microenvironment is highly inflammatory with remarkable TANs infiltration, which is often associated with unfavorable prognosis and advanced clinical stage. We find that TANs in LSCC display morphologically immature and lower apoptosis, exhibit distinctively immunosuppressive phenotype of high PD-L1, and suppress CD8+ T lymphocytes proliferation and activation. We subsequently discover that PD-L1+TANs induced by LSCC-derived GM-CSF potently impair CD8+ T-cells proliferation and cytokines production function, which are partially blocked by a PD-L1-neutralizing antibody. Clinical data further support GM-CSF as an unfavorable prognostic biomarker and reveal a potential association with inflammatory immune cell infiltration, in particular neutrophils. CONCLUSION: Tumor-infiltrating PD-L1+ neutrophils induced by LSCC-derived GM-CSF suppress T cell proliferation and activation in the inflammatory microenvironment of LSCC and predict unfavorable prognosis. These TANs cripple antitumor T cell immunity and promote tumor progression. Our findings provide a basis for targeting PD-L1+TANs or GM-CSF as a new immunotherapeutic strategy for LSCC.

Pre-metastatic Niche Formation by Neutrophils in Different Organs.

Metastasis is a multistep process requiring tumor cell detachment from the primary tumor and migration to secondary target organs through the lymphatic or blood circulatory systems. In certain cancers, specific organs are predisposed to metastases. Metastatic homing to distant organs is orchestrated by the formation of supportive metastatic microenvironment in such organs, called pre-metastatic niche. Formation of pre-metastatic niche depends on the primary tumor-mediated recruitment of bone marrow-derived myeloid cells, including neutrophils. The contribution of neutrophils to the formation of the pre-metastatic niche is recently getting growing attention. Of note, these cells can either stimulate or inhibit metastatic seeding, depending on the activation of these cells. Here, we concentrate on pro-metastatic functions of neutrophils and the mechanisms involved in this process. Pro-tumor neutrophils support the formation of pre-metastatic niche, attract tumor cells, and directly stimulate proliferation of these cells. Moreover, immunosuppressive neutrophils, also called granulocytic MDSC, promote metastatic progression by the inhibition of antitumor T-cells. Altogether, neutrophil pro-tumor properties significantly affect metastatic spread in the host. Here, we provide an up-to-date overview of roles neutrophils play in the regulation of metastatic processes in different organs.

The Recruitment of Neutrophils to the Tumor Microenvironment Is Regulated by Multiple Mediators.

Neutrophils sense and migrate towards chemotactic factors released at sites of infection/inflammation and contain the affected area using a variety of effector mechanisms. Aside from these established immune defense functions, neutrophils are emerging as one of the key tumor-infiltrating immune cells that influence cancer progression and metastasis. Neutrophil recruitment to the tumor microenvironment (TME) is mediated by multiple mediators including cytokines, chemokines, lipids, and growth factors that are secreted from cancer cells and cancer-associated stromal cells. However, the molecular mechanisms that underlie the expression and secretion of the different mediators from cancer cells and how neutrophils integrate these signals to reach and invade tumors remain unclear. Here, we discuss the possible role of the epithelial to mesenchymal transition (EMT) program, which is a well-established promoter of malignant potential in cancer, in regulating the expression and secretion of these key mediators. We also summarize and review our current understanding of the machineries that potentially control the secretion of the mediators from cancer cells, including the exocytic trafficking pathways, secretory autophagy, and extracellular vesicle-mediated secretion. We further reflect on possible mechanisms by which different mediators collaborate by integrating their signaling network, and particularly focus on TGF-ß, a cytokine that is highly expressed in invasive tumors, and CXCR2 ligands, which are crucial neutrophil recruiting chemokines. Finally, we highlight gaps in the field and the need to expand current knowledge of the secretory machineries and cross-talks among mediators to develop novel neutrophil targeting strategies as effective therapeutic options in the treatment of cancer.

T-cell immunoglobulin and ITIM domain, as a potential immune checkpoint target for immunotherapy of colorectal cancer.

The importance of the tumor microenvironment in cancer progression has been well studied for many years. Immune checkpoint inhibitors (ICIs) are regarded as potential strategies in enhancing the immune responses in patients with cancer, particularly colorectal cancer (CRC). Notably, CRCs are extraordinarily heterogeneous and mostly are microsatellite-stable (MSS) or cold tumors, which means that the immune response is not usually as strong as that of foreign cells. T-cell immunoglobulin and ITIM domain (TIGIT) is a new immune checkpoint receptor overexpressed inside the CRC tumor-immune microenvironments. Moreover, several studies have shown that TIGIT in combination with other ICIs and/or conventional treatments, can lead to a robust anti-tumor response in CRC. This review looks deep inside TIGIT expression patterns, their various functions, and possible immunotherapy strategies to increase survival rates and decrease immune-related adverse events.

Bioinformatics and immunohistochemistry analyses of expression levels and clinical significance of CXCL2 and TANs in an oral squamous cell carcinoma tumor microenvironment of Prophyromonas gingivalis infection.

The present study aimed to detect the immunoexpression and clinical significance of Porphyromonas gingivalis (P. gingivalis) in the tumor microenvironment (TME) of oral squamous cell carcinoma (OSCC). The immunoexpression of P. gingivalis in OSCC tissues was detected via immunohistochemistry (IHC) after P. gingivalis was infected into the TME of OSCC. To identify the differentially expressed genes in the carcinogenesis and progression of OSCC with P. gingivalis infection, microarray datasets (GSE87539 and GSE138206) were downloaded from the Gene Expression Omnibus database. The immunoexpression levels of C-X-C motif chemokine ligand 2 (CXCL2) and tumor-associated neutrophils (TANs) were also evaluated via IHC, and the immunoexpression levels of all three clinical variables were analyzed using χ2 or Fisher's exact tests. The survival rates were calculated using the Kaplan-Meier method and the survival curves were compared using log-rank tests. Predominantly strong immunoexpression of P. gingivalis was identified in OSCC samples. CXCL2 was considered to be a differential gene in the two datasets. Immunoexpression of P. gingivalis was positively associated with CXCL2 and TANs expression. Furthermore, P. gingivalis was associated with survival status (P<0.001) and differentiation (P<0.001). CXCL2 was associated with age (P=0.038) and survival status (P=0.003), while TANs were associated with T stage (P=0.015) and clinical stage (P=0.002). These clinical variables were considered to be independent risk factors for the poor prognosis of patients with OSCC. Collectively, the results suggested that the immunoexpression of P. gingivalis may be positively associated with CXCL2 and TANs. In addition, the strong immunoexpression levels of P. gingivalis, CXCL2 and TANs may be associated with a poor prognosis in patients with OSCC.

Anti-Ly6G binding and trafficking mediate positive neutrophil selection to unleash the anti-tumor efficacy of radiation therapy.

The anti-Ly6G antibody is used to deplete Ly6Gpos neutrophils and study their role in diverse pathologies. However, depletion is never absolute, as Ly6Glow neutrophils resistant to depletion rapidly emerge. Studying the functionality of these residual neutrophils is necessary to interpret anti-Ly6G-based experimental designs. In vitro, we found anti-Ly6G binding induced Ly6G internalization, surface Ly6G paucity, and primed the oxidative burst of neutrophils upon TNF α co-stimulation. In vivo, we found neutrophils resistant to anti-Ly6G depletion exhibited anti-neutrophil-cytoplasmic-antibodies. In the pre-clinical KrasLox-STOP-Lox-G12D/WT; Trp53Flox/Flox mouse lung tumor model, abnormal neutrophil accumulation and aging was accompanied with an N2-like SiglecFpos polarization and ly6g downregulation. Consequently, SiglecFpos neutrophils exposed to anti-Ly6G reverted to Ly6Glow and were resistant to depletion. Noting that anti-Ly6G mediated neutrophil depletion alone had no anti-tumor effect, we found a long-lasting rate of tumor regression (50%) by combining anti-Ly6G with radiation-therapy, in this model reputed to be refractory to standard anticancer therapies. Mechanistically, anti-Ly6G regulated neutrophil aging while radiation-therapy enhanced the homing of anti-Ly6G-boundSiglecFneg neutrophils to tumors. This anti-tumor effect was recapitulated by G-CSF administration prior to RT and abrogated with an anti-TNFα antibody co-administration. In summary, we report that incomplete depletion of neutrophils using targeted antibodies can intrinsically promote their oxidative activity. This effect depends on antigen/antibody trafficking and can be harnessed locally using select delivery of radiation-therapy to impair tumor progression. This underutilized aspect of immune physiology may be adapted to expand the scope of neutrophil-related research.

Tumor-associated neutrophils as new players in immunosuppressive process of the tumor microenvironment in breast cancer.

Despite the conventional reputation of neutrophils to have antibacterial properties, recent studies have put emphasis and are interested in the role of neutrophils in the spread and treatment of cancer. It has been shown that the infiltration of neutrophils, either by exerting pro- or anti-tumoral effects, probably affects tumor prognosis. Tumor-associated neutrophils (TANs) probably participate in tumor promotion and development in different ways, such as increasing genomic instability, induction of immunosuppression, and increasing angiogenesis. Despite major advances in breast cancer treatment, it is the second leading cause of death in American women. It has been revealed that inflammation is a fundamental issue in the treatment of this cancer because tumor growth, invasion, metastasis, and vascularization can be affected by inflammatory factors. It is demonstrated that enhanced neutrophil to lymphocyte ratio probably contributes to the raised rate of mortality and decreased survival among breast cancer cases. The present review explores the biology of TANs, their suspected interactions in the breast cancer microenvironment, and their functions in preserving the tumor microenvironment and progression of tumors. Furthermore, their potential as therapeutic targets and clinical biomarkers has been discussed in this paper.