Immune-mediated modulation of breast cancer growth and metastasis by the chemokine Mig (CXCL9) in a murine model

Targeting the tumor immune microenvironment: GPCRs as key regulators in triple-negative breast cancer

Triple-negative breast cancer (TNBC) poses a significant clinical challenge due to its aggressive nature and limited therapeutic options. Recent research underscores the pivotal role of G protein-coupled receptors (GPCRs) in shaping the tumor immune microenvironment (TIME) within TNBC. This review focuses on four principal GPCRs-chemokine receptors, sphingosine-1-phosphate receptors, prostaglandin E2 receptors, and lactate receptors-that have garnered substantial attention in TNBC studies. GPCRs modulate immune cell recruitment, polarization, and function, thereby fostering an immunosuppressive milieu conducive to tumor progression and metastasis. The review examines how alterations in GPCR expression on immune cells influence the pathogenesis and advancement of TNBC. Further, it discusses emerging therapeutic strategies targeting GPCR signaling pathways to remodel the immunosuppressive TIME in TNBC. These insights into GPCR-mediated immune regulation not only deepen our comprehension of TNBC's pathophysiology but also offer promising avenues for developing novel immunotherapies aimed at enhancing clinical outcomes for TNBC patients.

Combined use of NK cells and radiotherapy in the treatment of solid tumors

Natural killer (NK) cells are innate lymphocytes possessing potent tumor surveillance and elimination activity. Increasing attention is being focused on the role of NK cells in integral antitumor strategies (especially immunotherapy). Of note, therapeutic efficacy is considerable dependent on two parameters: the infiltration and cytotoxicity of NK cells in tumor microenvironment (TME), both of which are impaired by several obstacles (e.g., chemokines, hypoxia). Strategies to overcome such barriers are needed. Radiotherapy is a conventional modality employed to cure solid tumors. Recent studies suggest that radiotherapy not only damages tumor cells directly, but also enhances tumor recognition by immune cells through altering molecular expression of tumor or immune cells via the in situ or abscopal effect. Thus, radiotherapy may rebuild a NK cells-favored TME, and thus provide a cost-effective approach to improve the infiltration of NK cells into solid tumors, as well as elevate immune-activity. Moreover, the radioresistance of tumor always hampers the response to radiotherapy. Noteworthy, the puissant cytotoxic activity of NK cells not only kills tumor cells directly, but also increases the response of tumors to radiation via activating several radiosensitization pathways. Herein, we review the mechanisms by which NK cells and radiotherapy mutually promote their killing function against solid malignancies. We also discuss potential strategies harnessing such features in combined anticancer care.

Critical Roles of SRC-3 in the Development and Progression of Breast Cancer, Rendering It a Prospective Clinical Target

Breast cancer (BCa) is the most frequently diagnosed malignant tumor in women and is also one of the leading causes of cancer-related death. Most breast tumors are hormone-dependent and estrogen signaling plays a critical role in promoting the survival and malignant behaviors of these cells. Estrogen signaling involves ligand-activated cytoplasmic estrogen receptors that translocate to the nucleus with various co-regulators, such as steroid receptor co-activator (SRC) family members, and bind to the promoters of target genes and regulate their expression. SRC-3 is a member of this family that interacts with, and enhances, the transcriptional activity of the ligand activated estrogen receptor. Although SRC-3 has important roles in normal homeostasis and developmental processes, it has been shown to be amplified and overexpressed in breast cancer and to promote malignancy. The malignancy-promoting potential of SRC-3 is diverse and involves both promoting malignant behavior of tumor cells and creating a tumor microenvironment that has an immunosuppressive phenotype. SRC-3 also inhibits the recruitment of tumor-infiltrating lymphocytes with effector function and promotes stemness. Furthermore, SRC-3 is also involved in the development of resistance to hormone therapy and immunotherapy during breast cancer treatment. The versatility of SRC-3 in promoting breast cancer malignancy in this way makes it a good target, and methodical targeting of SRC-3 probably will be important for the success of breast cancer treatment.

Suppression of CD56bright NK cells in breast cancer patients is associated with the PD-1 and TGF-βRII expression

BACKGROUND

Natural killer (NK) cells, as professional cytotoxic cells, play a key role against cancer in the early and metastatic stages. Their functional defects are highly associated with the initiation or progression of breast cancer (BC). Here, we investigated the phenotypic characterization of NK cells in 26 newly diagnosed BC patients in comparison to 12 healthy counterparts.

METHODS

Expression of CXCR3 and PD-1, and also NKG2D, and TGF-βRII were studied on CD56^dim and CD56^bright NK cells from fresh peripheral blood (PB) samples using flow cytometry. The plasma levels of IFN-γ and soluble MIC-A levels were also assessed by ELISA.

RESULTS

Both CD56^dim and CD56^bright NK subtypes showed lower CXCR3 and NKG2D expression in BC patients than healthy subjects. Furthermore, patients' CD56^bright NK cells significantly showed higher expression levels of TGF-βRII and PD-1. Interestingly, increased concentration of MIC-A level in plasma of BC patients was associated with the higher TGF-βRII and PD-1 expression in all NK cells, while the plasma level of IFN-γ was associated with the lower TGF-βRII expression on CD56^bright NK cells in these patients.

CONCLUSION

Our results demonstrated phenotypically suppressed-NK cells, especially in the CD56^bright subset of BC patients. It specifies their potential incompetence and outlines decrement of their anti-tumor activity, which could be interrelated with the tumor pathogenesis, TME immunosuppression, and so disease progression. The induction of compensatory mechanisms revives NK cells function and could be used in combination with the conventional treatments as a putative therapeutic approach for targeted immunotherapy.

Comprehensive landscape of the IPAF inflammasomes in pan-cancer: A bulk omics research and single-cell sequencing validation

BACKGROUND

IPAF (ICE-protease Activating Factor) is a nucleotide-binding/leucine-rich repeat (NLR) protein known as the cysteine-associated recruitment domain 12 (CARD12). Previous studies only discuss the role of IPAF inflammasomes in specific tumors. The role of IPAF inflammasomes in pan-cancer is still unclear. Therefore, we performed a comprehensive analysis of IPAF inflammasome in 33 tumors.

METHODS

We used databases like The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) from the UCSC XENA (http://xena.ucsc.edu/) to retrieve and analyze gene expression. The influence of IPAF inflammasome on the prognosis of tumor patients was analyzed using univariate Cox regression analysis and Kaplan-Meier survival analysis. Furthermore, we conducted the following analysis: Single-sample gene set enrichment analysis, single-cell level functional state analysis, single-cell sequencing, immune cell infiltration analysis, and tumor immune dysfunction and exclusion (TIDE) score.

RESULTS

First, the differential expression of IPAF inflammasome-related genes (IPAF-RGs) in 33 tumors were analyzed. The results revealed that IPAF-RGs were significantly and differentially expressed in eight tumors. The prognostic significance of IPAF inflammasome scores was different in different tumors. A positive correlation was observed between IPAF inflammasomes scores and CD8+ T cells in most tumors. Further analysis revealed that IPAF inflammasome might affect tumor immunity mainly by mediating effector T cell recruitment via the expression of chemokines such as CXCL9, CXCL10, and CCL5. The analysis of TIDE and IPAF inflammasome scores revealed a significant negative correlation between IPAF inflammasome and TIDE scores in 11 tumors.

CONCLUSION

A pan-cancer analysis of IPAF inflammasome in various tumors was performed. The results highlight the potential value of IPAF inflammasome in response to immunotherapy in patients and provide a new direction for future immunotherapy.

Fn14-Directed DART Nanoparticles Selectively Target Neoplastic Cells in Preclinical Models of Triple-Negative Breast Cancer Brain Metastasis

Triple-negative breast cancer (TNBC) patients with brain metastasis (BM) face dismal prognosis due to the limited therapeutic efficacy of the currently available treatment options. We previously demonstrated that paclitaxel-loaded PLGA-PEG nanoparticles (NPs) directed to the Fn14 receptor, termed "DARTs", are more efficacious than Abraxane─an FDA-approved paclitaxel nanoformulation─following intravenous delivery in a mouse model of TNBC BM. However, the precise basis for this difference was not investigated. Here, we further examine the utility of the DART drug delivery platform in complementary xenograft and syngeneic TNBC BM models. First, we demonstrated that, in comparison to nontargeted NPs, DART NPs exhibit preferential association with Fn14-positive human and murine TNBC cell lines cultured in vitro. We next identified tumor cells as the predominant source of Fn14 expression in the TNBC BM-immune microenvironment with minimal expression by microglia, infiltrating macrophages, monocytes, or lymphocytes. We then show that despite similar accumulation in brains harboring TNBC tumors, Fn14-targeted DARTs exhibit significant and specific association with Fn14-positive TNBC cells compared to nontargeted NPs or Abraxane. Together, these results indicate that Fn14 expression primarily by tumor cells in TNBC BMs enables selective DART NP delivery to these cells, likely driving the significantly improved therapeutic efficacy observed in our prior work.

CXCL9-modified CAR T cells improve immune cell infiltration and antitumor efficacy

Chimeric antigen receptor (CAR) T cells remain unsatisfactory in treating solid tumors. The frequency of tumor-infiltrating T cells is closely related to the good prognosis of patients. Augmenting T cell accumulation in the tumor microenvironment is essential for tumor clearance. To overcome insufficient immune cell infiltration, innovative CAR designs need to be developed immediately. CXCL9 plays a pivotal role in regulating T cell migration and inhibiting tumor angiogenesis. Therefore, we engineered CAR T cells expressing CXCL9 (CART-CXCL9). The addition of CXCL9 enhanced cytokine secretion and cytotoxicity of CAR T cells and endowed CAR T cells with the ability to recruit activated T cells and antiangiogenic effect. In tumor-bearing mice, CART-CXCL9 cells attracted more T cell trafficking to the tumor site and inhibited angiogenesis than conventional CAR T cells. Additionally, CART-CXCL9 cell therapy slowed tumor growth and prolonged mouse survival, displaying superior antitumor activity. Briefly, modifying CAR T cells to express CXCL9 could effectively improve CAR T cell efficacy against solid tumors.

A comprehensive bioinformatics analysis to identify potential prognostic biomarkers among CC and CXC chemokines in breast cancer

Breast cancer (BC) is a major human health problem due to its increasing incidence and mortality rate. CC and CXC chemokines are associated with tumorigenesis and the progression of many cancers. Since the prognostic values of CC and CXC families' expression in various types of cancers are becoming increasingly evident, we aimed to conduct a comprehensive bioinformatics analysis elucidating the prognostic values of the CC and CXC families in BC. Therefore, TCGA, UALCAN, Kaplan–Meier plotter, bc-GenExMiner, cBioPortal, STRING, Enrichr, and TIMER were utilized for analysis. We found that high levels of CCL4/5/14/19/21/22 were associated with better OS and RFS, while elevated expression of CCL24 was correlated with shorter OS in BC patients. Also, high levels of CXCL9/13 indicated longer OS, and enhanced expression of CXCL12/14 was linked with better OS and RFS in BC patients. Meanwhile, increased transcription levels of CXCL8 were associated with worse OS and RFS in BC patients. In addition, our results showed that CCL5, CCL8, CCL14, CCL20, CCL27, CXCL4, and CXCL14 were notably correlated with the clinical outcomes of BC patients. Our findings provide a new point of view that may help the clinical application of CC and CXC chemokines as prognostic biomarkers in BC.

Role of chemokines in breast cancer

Chemokines belong to a family of chemoattractant cytokines and are well known to have an essential role in various cancer aetiologies. Multiplesubsets of immune cells are recruited and enrolled into the tumor microenvironment through interactions between chemokines and their specific receptors. These populations and their interactions have a distinct impact on tumor growth, progression, and treatment outcomes. While it is clear that many chemokines and their cognate receptors can be detected in breast and other cancers, the role of each chemokine and receptor has yet to be determined. This review focuses on the main chemokines that play a crucial role in the tumor microenvironment, emphasizing breast cancer. We have also discussed the techniques used to identify the chemokines and their future implication in the early diagnosis of cancer. In-depth knowledge of chemokines and their role in breast cancer progression can provide specific targets for breast cancer biotherapy.

Epithelial-Mesenchymal Transition-Based Gene Signature and Distinct Molecular Subtypes for Predicting Clinical Outcomes in Breast Cancer

Purpose

Regulation of inducers and transcription factor families influence epithelial–mesenchymal transition (EMT), a contributing factor to breast cancer invasion and progression.

Methods

Molecular subtypes were classified based on EMT-related mRNAs using ConsensusClusterPlus package. Differences in tumor immune microenvironment and prognosis were assessed among subtypes. Based on EMT genes, a gene signature for prognosis was built using TCGA training set by performing multivariate and univariate Cox regression analyses. Prediction accuracy of the signature was validated by receiver operating characteristic (ROC) curves and overall survival analysis on internal and external datasets. By conducting univariate and multivariate Cox regression analyses, the risk signature as an independent prognostic indicator was assessed. A nomogram was constructed and validated by calibration analysis and decision curve analysis (DCA).

Results

Five molecular subtypes were characterized based on EMT genes. Patients in Cluster 2 exhibited an activated immune state and a better prognosis. An 11-EMT gene-signature was built to predict breast cancer prognosis. After validation, the signature showed independence and robustness in predicting clinical outcomes of patients. A nomogram combining the RiskScore and pTNM_stage accurately predicted 1-, 2-, 3-, and 5-year survival chance. In comparison with published model, the current model showed a higher area under the curve (AUC).

Conclusion

We characterized five breast cancer subtypes with distinct clinical outcomes and immune status. The study developed an 11-EMT gene-signature as an independent prognostic factor for predicting clinical outcomes of breast cancer.

Chemokines in the Landscape of Cancer Immunotherapy: How They and Their Receptors Can Be Used to Turn Cold Tumors into Hot Ones?

Over the last decade, monoclonal antibodies to immune checkpoint inhibitors (ICI), also known as immune checkpoint blockers (ICB), have been the most successful approach for cancer therapy. Starting with mAb to cytotoxic T lymphocyte antigen 4 (CTLA-4) inhibitors in metastatic melanoma and continuing with blockers of the interactions between program cell death 1 (PD-1) and its ligand program cell death ligand 1 (PDL-1) or program cell death ligand 2 (PDL-2), that have been approved for about 20 different indications. Yet for many cancers, ICI shows limited success. Several lines of evidence imply that the limited success in cancer immunotherapy is associated with attempts to treat patients with "cold tumors" that either lack effector T cells, or in which these cells are markedly suppressed by regulatory T cells (Tregs). Chemokines are a well-defined group of proteins that were so named due to their chemotactic properties. The current review focuses on key chemokines that not only attract leukocytes but also shape their biological properties. CXCR3 is a chemokine receptor with 3 ligands. We suggest using Ig-based fusion proteins of two of them: CXL9 and CXCL10, to enhance anti-tumor immunity and perhaps transform cold tumors into hot tumors. Potential differences between CXCL9 and CXCL10 regarding ICI are discussed. We also discuss the possibility of targeting the function or deleting a key subset of Tregs that are CCR8+ by monoclonal antibodies to CCR8. These cells are preferentially abundant in several tumors and are likely to be the key drivers in suppressing anti-cancer immune reactivity.

Cytokines screening identifies MIG (CXCL9) for postoperative recurrence prediction in operated non-small cell lung cancer patients

BACKGROUND

Exploration of reliable biomarkers most likely to identify non-small cell lung cancer (NSCLC) patients at high risk for recurrence after surgery is needed.

METHODS

Quantibody® Human Cytokine Antibody 6000 was used as screening tool to measure serum levels of 280 cytokines in ten healthy individuals and nine samples from three NSCLC patients before operation, after operation and postoperative recurrence. Selected cytokines were validated in two independent sets (89 patients before surgery, 69 patients after surgery and 40 patients with postoperative recurrence for each set) using ELISA method. The association of the selected cytokine with clinicopathologic features was also evaluated.

RESULTS

Thirty-six cytokines were declined after surgery and again elevated when recurrence. We selected MIG to be further assessed in 2 validation sets, the mean value of serum MIG levels in 396 NSCLC patients was 253.42 ± 274.48 pg/mL and was significantly higher than the level in 60 healthy controls (47.65 ± 33.23 pg/mL, P < 0.0001). The serum MIG levels were 366.36 ± 324.04 pg/mL pre-operation, 134.04 ± 127.52 pg/mL post-operation and 208.05 ± 239.39 pg/mL in recurrence in NSCLC patients. The serum MIG levels were significant differences among NSCLC patients of pre-operation, post-operation and recurrence and controls (P < 0.0001). Moreover, Serum MIG levels were decreased markedly after operation and notably increased when disease relapsed (P < 0.0005). Serum MIG levels trend to be higher in patients with male gender, older age, smoking habit, poor tumor differentiation, and non-adenocarcinoma histology.

CONCLUSIONS

These data indicated that MIG might be an indicator of postoperative recurrence and help to identify NSCLC patient who was easy to relapse after surgery.

Mitochondrial respiration contributes to the interferon gamma response in antigen-presenting cells

The immunological synapse allows antigen-presenting cells (APCs) to convey a wide array of functionally distinct signals to T cells, which ultimately shape the immune response. The relative effect of stimulatory and inhibitory signals is influenced by the activation state of the APC, which is determined by an interplay between signal transduction and metabolic pathways. While pathways downstream of toll-like receptors rely on glycolytic metabolism for the proper expression of inflammatory mediators, little is known about the metabolic dependencies of other critical signals such as interferon gamma (IFNγ). Using CRISPR-Cas9, we performed a series of genome-wide knockout screens in murine macrophages to identify the regulators of IFNγ-inducible T cell stimulatory or inhibitory proteins MHCII, CD40, and PD-L1. Our multiscreen approach enabled us to identify novel pathways that preferentially control functionally distinct proteins. Further integration of these screening data implicated complex I of the mitochondrial respiratory chain in the expression of all three markers, and by extension the IFNγ signaling pathway. We report that the IFNγ response requires mitochondrial respiration, and APCs are unable to activate T cells upon genetic or chemical inhibition of complex I. These findings suggest a dichotomous metabolic dependency between IFNγ and toll-like receptor signaling, implicating mitochondrial function as a fulcrum of innate immunity.

Contribution of CXCR3-mediated signaling in the metastatic cascade of solid malignancies

Metastasis is a significant cause of the mortality resulting from solid malignancies. The process of metastasis is complex and is regulated by numerous cancer cell-intrinsic and -extrinsic factors. CXCR3 is a chemokine receptor that is frequently expressed by cancer cells, endothelial cells and immune cells. CXCR3A signaling in cancer cells tends to promote the invasive and migratory phenotype of cancer cells. Indirectly, CXCR3 modulates the anti-tumor immune response resulting in variable effects that can permit or inhibit metastatic progression. Finally, the activity of CXCR3B in endothelial cells is generally angiostatic, which limits the access of cancer cells to key conduits to secondary sites. However, the interaction of these activities within a tumor and the presence of opposing CXCR3 splice variants clouds the picture of the role of CXCR3 in metastasis. Consequently, thorough analysis of the contributions of CXCR3 to cancer metastasis is necessary. This review is an in-depth examination of the involvement of CXCR3 in the metastatic process of solid malignancies.

CXCL9 Is a Potential Biomarker of Immune Infiltration Associated With Favorable Prognosis in ER-Negative Breast Cancer

The chemokine CXCL9 (C-X-C motif chemokine ligand 9) has been reported to be required for antitumour immune responses following immune checkpoint blockade. In this study, we sought to investigate the potential value of CXCL9 according to immune responses in patients with breast cancer (BC). A variety of open-source databases and online tools were used to explore the expression features and prognostic significance of CXCL9 in BC and its correlation with immune-related biomarkers followed by subsequent verification with immunohistochemistry experiments. The CXCL9 mRNA level was found to be significantly higher in BC than in normal tissue and was associated with better survival outcomes in patients with ER-negative tumours. Moreover, CXCL9 is significantly correlated with immune cell infiltration and immune-related biomarkers, including CTLA4, GZMB, LAG3, PDCD1 and HAVCR2. Finally, we performed immunohistochemistry with breast cancer tissue samples and observed that CXCL9 is highly expressed in the ER-negative subgroup and positively correlated with the immune-related factors LAG3, PD1, PDL1 and CTLA4 to varying degrees. These findings suggest that CXCL9 is an underlying biomarker for predicting the status of immune infiltration in ER-negative breast cancer.

Tumor inhibition or tumor promotion? The duplicity of CXCR3 in cancer

Tumor tissue includes cancer cells and normal stromal cells such as vascular endothelial cells, connective tissue cells (cancer associated fibroblast, mesenchymal stem cell), and immune cells (tumor-infiltrating lymphocytes or TIL, dendritic cells, eosinophils, basophils, mast cells, tumor-associated macrophages or TAM, myeloid-derived suppressor cells or MDSC). Anti-tumor activity is mainly mediated by infiltration of NK cells, Th1 and CD8⁺ T cells, and correlates with expression of NK cell and T cell attracting chemokines. Nevertheless, cancer cells hijack tissue homeostasis through secretion of cytokines and chemokines that mediate not only the induction of an inflamed status that supports cancer cell survival and growth, but also the recruitment and/or activation of immune suppressive cells. CXCL9, CXCL10, and CXCL11 are known for their tumor-inhibiting properties, but their overexpression in several hematologic and solid tumors correlates with disease severity, suggesting a role in tumor promotion. The dichotomous nature of CXCR3 ligands activity mainly depends on several molecular mechanisms induced by cancer cells themselves able to divert immune responses and to alter the whole local environment. A deep understanding of the nature of such phenomenon may provide a rationale to build up a CXCR3/ligand axis targeting strategy. In this review, we will discuss the role of CXCR3 in cancer progression and in regulation of anti-tumor immune response and immunotherapy.

Endogenous CXCL9 affects prognosis by regulating tumor-infiltrating natural killer cells in intrahepatic cholangiocarcinoma

CXCL9, an IFN‐γ inducible chemokine, has been reported to play versatile roles in tumor‐host interrelationships. However, little is known about its role in intrahepatic cholangiocarcinoma (iCCA). Here, we aimed to elucidate the prognostic and biological implications of CXCL9 in iCCA. Endogenous CXCL9 expression and the number of tumor‐infiltrating lymphocytes were immunohistochemically assessed in resection specimens. These data were validated in mice treated by silencing CXCL9 with short hairpin RNA. In addition, the induction of endogenous CXCL9 and the effects of CXCL9 on tumor biological behaviors were evaluated in human cholangiocarcinoma cell lines. Immunohistochemical analyses revealed that high CXCL9 expression was closely correlated with prolonged postoperative survival and a large number of tumor‐infiltrating natural killer (NK) cells. In fact, due to the trafficking of total and tumor necrosis factor‐related apoptosis‐inducing ligand‐expressing NK cells into tumors, CXCL9‐sufficient cells were less tumorigenic in the liver than CXCL9‐deficient cells in mice. Although CXCL9 involvement in tumor growth and invasion abilities differed across cell lines, it did not exacerbate these abilities in CXCL9‐expressing cell lines. We showed that CXCL9 was useful as a prognostic marker. Our findings also suggested that CXCL9 upregulation might offer a therapeutic strategy for treating CXCL9‐expressing iCCA by augmenting anti–tumor immune surveillance.

The Role of CXCL13 and CXCL9 in Early Breast Cancer

BACKGROUND

Chemokines, cytokines in the immune microenvironment of tumors, may be associated with patient outcome. We assessed the impact of CXCL13 and CXCL9 on disease-free (DFS) and overall survival (OS), in an attempt to retrospectively evaluate both T and B cell function in the microenvironment of primary tumors from patients with breast cancer.

MATERIALS AND METHODS

Formalin-fixed paraffin-embedded tissue blocks from patients with intermediate/high-risk, early breast cancer, treated with sequential adjuvant epirubicin, paclitaxel, and cyclophosphamide methotrexate fluorouracil within a randomized trial, were tested for CXCL13 and CXCL9 messenger RNA expression; 557 patients with adequate tissue were eligible for the analysis.

RESULTS

CXCL13 was correlated with CXCL9 (rho = 0.52; P < .001). High-expressing CXL13 and CXCL9 tumors had higher Ki67 and tumor infiltrating lymphocyte density (P-values < .001). High CXCL9 expression was an unfavorable prognosticator for OS among all patients (hazard ratio [HR], 1.73; P = .021), whereas it showed favorable significance for both DFS and OS in patients with triple negative disease (HR, 0.29; P = .027 and HR, 0.32; P = .045). High CXCL13 conferred longer DFS and OS among patients with luminal-human epidermal growth factor receptor 2 disease (HR, 0.31; P = .013 and HR, 0.25; P = .005). Patients with low CXCL13 and high CXCL9 expression had shorter DFS and OS compared with those with high expression of both chemokines (HR, 1.63; P = .006 and HR, 1.61; P = .016).

CONCLUSIONS

Both biomarkers were associated with poor prognosis characteristics and with tumor infiltrating lymphocyte density. High CXCL9 conferred an improved prognosis in the triple negative subtype, whereas high CXCL13 was associated with improved outcome in the luminal-human epidermal growth factor receptor 2 subtype. Chemokines can be associated with breast cancer subtype and outcome. These data should be evaluated prospectively.

Comprehensive network map of interferon gamma signaling

Interferon gamma (IFN-γ), is a cytokine, which is an important regulator of host defense system by mediating both innate and adaptive immune responses. IFN-γ signaling is primarily associated with inflammation and cell-mediated immune responses. IFN-γ is also represented as antitumor cytokine which facilitates immunosurveillance in tumor cells. In addition, IFN-γ mediated signaling also elicits pro-tumorigenic transformations and promotes tumor progression. Impact of IFN-γ signaling in mammalian cells has been widely studied which indicate that IFN-γ orchestrates distinct cellular functions including immunomodulation, leukocyte trafficking, apoptosis, anti-microbial, and both anti- and pro-tumorigenic role. However, a detailed network of IFN-γ signaling pathway is currently lacking. Therefore, we systematically curated the literature information pertaining to IFN-γ signaling and develop a comprehensive signaling network to facilitate better understanding of IFN-γ mediated signaling. A total of 124 proteins were catalogued that were experimentally proven to be involved in IFN-γ signaling cascade. These 124 proteins were found to participate in 81 protein-protein interactions, 94 post-translational modifications, 20 translocation events, 54 activation/inhibiton reactions. Further, 236 differential expressed genes were also documented in IFN-γ mediated signaling. IFN-γ signaling pathway is made freely available to scientific audience through NetPath at ( http://www.netpath.org/pathways?path_id=NetPath_32 ). We believe that documentation of reactions pertaining to IFN-γ signaling and development of pathway map will facilitate further research in IFN-γ associated human diseases including cancer.

Functions of the CXC ligand family in the pancreatic tumor microenvironment

Therapeutic resistance is the major contributor to the poor prognosis of and low survival from pancreatic cancer (PC). Cancer progression is a complex process reliant on interactions between the tumor and the tumor microenvironment (TME). Members of the CXCL family of chemokines are present in the pancreatic TME and seem to play a vital role in regulating PC progression. As pancreatic tumors interact with the TME and with PC stem cells (CSCs), determining the roles of specific members of the CXCL family is vital to the development of improved therapies. This review highlights the roles of selected CXCLs in the interactions between pancreatic tumor and its stroma, and in CSC phenotypes, which can be used to identify potential treatment targets.

The Role of CXC Chemokine Receptors 1-4 on Immune Cells in the Tumor Microenvironment

Chemokines govern leukocyte migration by attracting cells that express their cognate ligands. Many cancer types show altered chemokine secretion profiles, favoring the recruitment of pro-tumorigenic immune cells and preventing the accumulation of anti-tumorigenic effector cells. This can ultimately result in cancer immune evasion. The manipulation of chemokine and chemokine-receptor signaling can reshape the immunological phenotypes within the tumor microenvironment in order to increase the therapeutic efficacy of cancer immunotherapy. Here we discuss the three chemokine-chemokine receptor axes, CXCR1/2–CXCL1-3/5-8, CXCR3–CXCL9/10/11, and CXCR4-CXCL12 and their role on pro-tumorigenic immune cells and anti-tumorigenic effector cells in solid tumors. In particular, we summarize current strategies to target these axes and discuss their potential use in treatment approaches.

Distribution and prognostic value of tumor‑infiltrating T cells in breast cancer

Tumor-infiltrating lymphocytes are associated with the response to neoadjuvent chemotherapy and prognosis in breast cancer. However, the distribution, interaction and prognostic value of tumor‑infiltrating T cells, the main component of the tumor microenvironment, have seldom been reported. In the present study, surgical specimens of 72 breast cancer patients were analyzed. Tumor‑infiltrating T cell subsets [cluster of differentiation (CD)4+T, CD8+T and regulatory T cells] and expression of their cytokines [interferon‑γ, interleukin (IL)‑4, and IL‑17] were evaluated by flow cytometry. These parameters together with The Cancer Genome Atlas database were used to demonstrate the distribution, interaction and prognostic value of tumor‑infiltrating T cells in breast cancer. Tumor‑infiltrating lymphocytes were closely associated with histological grade (P=0.03), estrogen receptor status (P=0.006), human epidermal growth factor receptor 2 status (P=0.047) and molecular subtype in breast cancer (P=0.012). The gene expression of CD4, CD8A and forkhead box protein P3 in the tumor was increased compared with healthy breast tissue, and was positively associated with the prognosis of breast cancer patients. HER2+ and triple‑negative breast cancer exhibited a significantly increased percentage of CD4+T cells (P=0.01) and regulatory T cells (P=0.035), and a decreased percentage of CD8+T cells (P=0.006) compared with the luminal subtype. Furthermore, the regulatory T cell number was positively correlated with CD8+T cell number in tumors (R=0.7, P=1.5x10‑162) and significantly inhibited the cytokine secretion of T cells. These results reveal the distribution and interaction of tumor‑infiltrating T cell subsets, and indicate that CD8+T cells and regulatory T cells may be used as reliable predictors of prognosis in breast cancer.

Human Placental-Derived Adherent Stromal Cells Co-Induced with TNF-α and IFN-γ Inhibit Triple-Negative Breast Cancer in Nude Mouse Xenograft Models

Culturing 3D-expanded human placental-derived adherent stromal cells (ASCs) in the presence of tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) transiently upregulated the secretion of numerous anti-proliferative, anti-angiogenic and pro-inflammatory cytokines. In a 3D-spheroid screening assay, conditioned medium from these induced-ASCs inhibited proliferation of cancer cell lines, including triple-negative breast cancer (TNBC) lines. In vitro co-culture studies of induced-ASCs with MDA-MB-231 human breast carcinoma cells, a model representing TNBC, supports a mechanism involving immunomodulation and angiogenesis inhibition. In vivo studies in nude mice showed that intramuscular administration of induced-ASCs halted MDA-MB-231 cell proliferation, and inhibited tumor progression and vascularization. Thirty percent of treated mice experienced complete tumor remission. Murine serum concentrations of the tumor-supporting cytokines Interleukin-6 (IL-6), Vascular endothelial growth factor (VEGF) and Granulocyte-colony stimulating factor (G-CSF) were lowered to naïve levels. A somatic mutation analysis identified numerous genes which could be screened in patients to increase a positive therapeutic outcome. Taken together, these results show that targeted changes in the secretion profile of ASCs may improve their therapeutic potential.

CXCL9, CXCL10, CXCL11/CXCR3 axis for immune activation - A target for novel cancer therapy

Chemokines are proteins which induce chemotaxis, promote differentiation of immune cells, and cause tissue extravasation. Given these properties, their role in anti-tumor immune response in the cancer environment is of great interest. Although immunotherapy has shown clinical benefit for some cancer patients, other patients do not respond. One of the mechanisms of resistance to checkpoint inhibitors may be chemokine signaling. The CXCL9, -10, -11/CXCR3 axis regulates immune cell migration, differentiation, and activation, leading to tumor suppression (paracrine axis). However, there are some reports that show involvements of this axis in tumor growth and metastasis (autocrine axis). Thus, a better understanding of CXCL9, -10, -11/CXCR3 axis is necessary to develop effective cancer control. In this article, we summarize recent evidence regarding CXCL9, CXCL10, CXCL11/CXCR3 axis in the immune system and discuss their potential role in cancer treatment.

An integrated method for the identification of novel genes related to oral cancer

Cancer is a significant public health problem worldwide. Complete identification of genes related to one type of cancer facilitates earlier diagnosis and effective treatments. In this study, two widely used algorithms, the random walk with restart algorithm and the shortest path algorithm, were adopted to construct two parameterized computational methods, namely, an RWR-based method and an SP-based method; based on these methods, an integrated method was constructed for identifying novel disease genes. To validate the utility of the integrated method, data for oral cancer were used, on which the RWR-based and SP-based methods were trained, thereby building two optimal methods. The integrated method combining these optimal methods was further adopted to identify the novel genes of oral cancer. As a result, 85 novel genes were inferred, among which eleven genes (e.g., MYD88, FGFR2, NF-κBIA) were identified by both the RWR-based and SP-based methods, 70 genes (e.g., BMP4, IFNG, KITLG) were discovered only by the RWR-based method and four genes (L1R1, MCM6, NOG and CXCR3) were predicted only by the SP-based method. Extensive analyses indicate that several novel genes have strong associations with cancers, indicating the effectiveness of the integrated method for identifying disease genes.

Induction of cathepsin B by the CXCR3 chemokines CXCL9 and CXCL10 in human breast cancer cells

Cathepsin B (CTSB) is a lysosomal cysteine protease that has been linked to the progression of breast cancer, for example by activation of other proteases and tumor-promoting cytokines, thereby supporting tumor invasion and metastasis. Previously, it was shown that CTSB cleaves and inactivates C-X-C motif chemokine receptor 3 (CXCR3) chemokines. As CXCR3 ligands have been demonstrated to induce proteases in cancer cells, the present study hypothesized that they may also affect CTSB in breast cancer cells. The results demonstrated that the human breast cancer tumor cell lines MCF-7 and MDA-MB-231 express the CXCR3 splice variants A and B and CTSB. Upon binding to CXCR3, the two chemokine ligands C-X-C motif chemokine ligand (CXCL) 9 and CXCL10 trigger upregulation of CTSB in these breast cancer cells, whereas the CXCR3-B-specific ligand CXCL4 has no such effect, suggesting the involvement of CXCR3-A in the regulation of CTSB. In early-stage human breast cancer specimens (n=81), overexpression of CXCR3 is associated with statistically significant poorer overall survival, independent of lymph node status, tumor size and nuclear grading (hazard ratio=1.99; 95% confidence interval=1.00–3.97; P=0.050). In conclusion, the data from the current study propose a so far unknown mechanism by which breast cancer cells may exploit tumor-suppressive chemokines to enhance their invasiveness and reduce immune cell infiltration by the degradation of these chemokines. This mechanism may support the established unfavorable prognostic feature of CXCR3 expression in breast cancer.

CXCL9: evidence and contradictions for its role in tumor progression

Chemokines are a group of low molecular weight peptides. Their major function is the recruitment of leukocytes to inflammation sites, but they also play a key role in tumor growth, angiogenesis, and metastasis. In the last few years, accumulated experimental evidence supports that monokine induced by interferon (IFN)‐gamma (CXCL9), a member of CXC chemokine family and known to attract CXCR3‐ (CXCR3‐A and CXCR3‐B) T lymphocytes, is involved in the pathogenesis of a variety of physiologic diseases during their initiation and their maintenance. This review for the first time presents the most comprehensive summary for the role of CXCL9 in different types of tumors, and demonstrates its contradictory role of CXCL9 in tumor progression. Altogether, this is a useful resource for researchers investigating therapeutic opportunities for cancer.

CXCR3 as a molecular target in breast cancer metastasis: inhibition of tumor cell migration and promotion of host anti-tumor immunity

Chemokines and chemokine receptors have critical roles in cancer metastasis and have emerged as one of the targeting options in cancer therapy. However, the treatment efficacy on both tumor and host compartments needs to be carefully evaluated. Here we report that targeting CXCR3 decreased tumor cell migration and at the same time improved host anti-tumor immunity. We observed an increased expression of CXCR3 in metastatic tumor cells compared to those from non-metastatic tumor cells. Knockdown (KD) of CXCR3 in metastatic tumor cells suppressed tumor cell migration and metastasis. Importantly, CXCR3 expression in clinical breast cancer samples correlated with progression and metastasis. For the host compartment, deletion of CXCR3 in all host cells in 4T1 mammary tumor model significantly decreased metastasis. The underlying mechanisms involve a decreased expression of IL-4, IL-10, iNOs, and Arg-1 in myeloid cells and an increased T cell response. IFN-γ neutralization diminished the metastasis inhibition in the CXCR3 knockout (KO) mice bearing 4T1 tumors, suggesting a critical role of host CXCR3 in immune suppression. Consistently, targeting CXCR3 using a small molecular inhibitor (AMG487) significantly suppressed metastasis and improved host anti-tumor immunity. Our findings demonstrate that targeting CXCR3 is effective in both tumor and host compartments, and suggest that CXCR3 inhibition is likely to avoid adverse effects on host cells.

NLRC4 suppresses melanoma tumor progression independently of inflammasome activation

Members of the NLR family can assemble inflammasome complexes with the adaptor protein ASC and caspase-1 that result in the activation of caspase-1 and the release of IL-1β and IL-18. Although the NLRC4 inflammasome is known to have a protective role in tumorigenesis, there is an increased appreciation for the inflammasome-independent actions of NLRC4. Here, we utilized a syngeneic subcutaneous murine model of B16F10 melanoma to explore the role of NLRC4 in tumor suppression. We found that NLRC4-deficient mice exhibited enhanced tumor growth that was independent of the inflammasome components ASC and caspase-1. Nlrc4 expression was critical for cytokine and chemokine production in tumor-associated macrophages and was necessary for the generation of protective IFN-γ-producing CD4+ and CD8+ T cells. Tumor progression was diminished when WT or caspase-1-deficient, but not NLRC4-deficient, macrophages were coinjected with B16F10 tumor cells in NLRC4-deficient mice. Finally, examination of human primary melanomas revealed the extensive presence of NLRC4+ tumor-associated macrophages. In contrast, there was a paucity of NLRC4+ tumor-associated macrophages observed in human metastatic melanoma, supporting the concept that NLRC4 expression controls tumor growth. These results reveal a critical role for NLRC4 in suppressing tumor growth in an inflammasome-independent manner.

A monoclonal antibody against KCNK9 K(+) channel extracellular domain inhibits tumour growth and metastasis

Two-pore domain potassium (K2P) channels act to maintain cell resting membrane potential--a prerequisite for many biological processes. KCNK9, a member of K2P family, is implicated in cancer, owing to its overexpression in human tumours and its ability to promote neoplastic cell survival and growth. However, KCNK9's underlying contributions to malignancy remain elusive due to the absence of specific modulators. Here we describe the development of monoclonal antibodies against the KCNK9 extracellular domain and their functional effects. We show that one antibody (Y4) with the highest affinity binding induces channel internalization. The addition of Y4 to KCNK9-expressing carcinoma cells reduces cell viability and increases cell death. Systemic administration of Y4 effectively inhibits growth of human lung cancer xenografts and murine breast cancer metastasis in mice. Evidence for Y4-mediated carcinoma cell autonomous and immune-dependent cytotoxicity is presented. Our study reveals that antibody-based KCNK9 targeting is a promising therapeutic strategy in KCNK9-expressing malignancies.

Gene therapy with IL-12 induced enhanced anti-tumor activity in fibrosarcoma mouse model

Context Immunotherapy is among the most promising modalities for treatment of cancer. Recently, interleukin 12 (IL-12) has been used as an immunotherapeutic agent in cancer gene therapy. IL-12 can activate dendritic cells (DCs) and boost anti-tumor immune responses. Objective In the current study, we have investigated if IL-12 gene therapy can lead to the regression of tumor mass in a mouse model of fibrosarcoma. Material and methods To investigate the therapeutic efficacy of IL-12, WEHI-164 tumor cells were transfected with murine-IL12 plasmids using Lipofectamine. Enzyme linked immunosorbent assay (ELISA) was used to confirm IL-12 expression in transfected cells. The fibrosarcoma mouse model was established by subcutaneous injection of transfected cells to Balb/C mice. Mice were sacrificed and the tumors were extracted. Tumor sizes were measured by caliper. The expression of IL-12 and IFN-γ was studied with real-time PCR and western blotting. The expression of Ki-67(a tumor proliferation marker) in tumor mass was studied by immunohistochemistry staining. Results and discussion The group treated with IL-12 showed a significant decrease in tumor mass volume (P: 0.000). The results of real-time PCR and western blotting showed that IL-12 and IFN-γ expression increased in the group treated with IL-12 (relative expression of IL-12: 1.9 and relative expression of IFN-γ: 1.766). Immunohistochemistry staining showed that Ki-67 expression was reduced in the group treated with IL-12. Conclusion IL-12 gene therapy successfully led to regress of tumor mass in the fibrosarcoma mouse model. This may serve as a candidate therapeutic approach for treatment of cancer.

Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: focus on the cancer hallmark of tumor angiogenesis

One of the important 'hallmarks' of cancer is angiogenesis, which is the process of formation of new blood vessels that are necessary for tumor expansion, invasion and metastasis. Under normal physiological conditions, angiogenesis is well balanced and controlled by endogenous proangiogenic factors and antiangiogenic factors. However, factors produced by cancer cells, cancer stem cells and other cell types in the tumor stroma can disrupt the balance so that the tumor microenvironment favors tumor angiogenesis. These factors include vascular endothelial growth factor, endothelial tissue factor and other membrane bound receptors that mediate multiple intracellular signaling pathways that contribute to tumor angiogenesis. Though environmental exposures to certain chemicals have been found to initiate and promote tumor development, the role of these exposures (particularly to low doses of multiple substances), is largely unknown in relation to tumor angiogenesis. This review summarizes the evidence of the role of environmental chemical bioactivity and exposure in tumor angiogenesis and carcinogenesis. We identify a number of ubiquitous (prototypical) chemicals with disruptive potential that may warrant further investigation given their selectivity for high-throughput screening assay targets associated with proangiogenic pathways. We also consider the cross-hallmark relationships of a number of important angiogenic pathway targets with other cancer hallmarks and we make recommendations for future research. Understanding of the role of low-dose exposure of chemicals with disruptive potential could help us refine our approach to cancer risk assessment, and may ultimately aid in preventing cancer by reducing or eliminating exposures to synergistic mixtures of chemicals with carcinogenic potential.

Regulation of chemokine expression in the tumor microenvironment

Chemokines are chemotactic cytokines critical for homeostatic and inflammation-induced trafficking of leukocytes during immune responses, hematopoesis, wound healing, and tumorigenesis. Despite three decades of intensive study of the chemokine network, the molecular mechanisms regulating chemokine expression during tumor growth are not well understood. In this review, we focus on the role of chemokines in both tumor growth and anti-tumor immune responses and on molecular mechanisms employed by tumor cells to regulate chemokine expression in the tumor microenvironment. Multiple mechanisms used by tumors to regulate chemokine production, including those revealed by very recent studies (such as DNA methylation or post-translational nitrosylation of chemokines) are discussed. Concluding the review, we discuss how understanding of these regulatory mechanisms can be used in cancer therapy to suppress tumor growth and/or to promote immune-mediated eradication of tumors.

CXCR3 deficiency enhances tumor progression by promoting macrophage M2 polarization in a murine breast cancer model

Tumor associated macrophages play a vital role in determining the outcome of breast cancer. We investigated the contribution of the chemokine receptor CXCR3 to antitumor immune responses using a cxcr3 deficient mouse orthotopically injected with a PyMT breast cancer cell line. We observed that cxcr3 deficient mice displayed increased IL-4 production and M2 polarization in the tumors and spleens compared to WT mice injected with PyMT cells. This was accompanied by larger tumor development in cxcr3(-/-) than in WT mice. Further, tumor-promoting myeloid derived immune cell populations accumulated in higher proportions in the spleens of cxcr3 deficient mice. Interestingly, cxcr3(-/-) macrophages displayed a deficiency in up-regulating inducible nitric oxide synthase after stimulation by either IFN-γ or PyMT supernatants. Stimulation of bone marrow derived macrophages by PyMT supernatants also resulted in greater induction of arginase-1 in cxcr3(-/-) than WT mice. Further, cxcr3(-/-) T cells activated with CD3/CD28 in vitro produced greater amounts of IL-4 and IL-10 than T cells from WT mice. Our data suggests that a greater predisposition of cxcr3 deficient macrophages towards M2 polarization contributes to an enhanced tumor promoting environment in cxcr3 deficient mice. Although CXCR3 is known to be expressed on some macrophages, this is the first report that demonstrates a role for CXCR3 in macrophage polarization and subsequent breast tumor outcomes. Targeting CXCR3 could be a potential therapeutic approach in the management of breast cancer tumors.

Mammary carcinoma cell derived cyclooxygenase 2 suppresses tumor immune surveillance by enhancing intratumoral immune checkpoint activity

INTRODUCTION

Systemic inhibition of the inflammatory enzyme cyclooxygenase (COX) 2 decreases the risk of breast cancer and its recurrence. However, the biology of COX-2 in the multicellular tumor microenvironment is poorly defined.

METHODS

Mammary tumor onset and multiplicity were examined in ErbB2 transgenic mice that were deficient in mammary epithelial cell COX-2 (COX-2(MEC)KO) compared to wild type (WT) mice. Tumors were analyzed, by real time PCR, immune-staining and flow cytometry, for proliferation, apoptosis, angiogenesis and immune microenvironment. Lentiviral shRNA delivery was used to knock down (KD) COX-2 in ErbB2-transformed mouse breast cancer cells (COX-2KD), and growth as orthotopic tumors was examined in syngenic recipient mice, with or without depletion of CD8+ immune cells.

RESULTS

Mammary tumor onset was delayed, and multiplicity halved, in COX-2(MEC)KO mice compared to WT. COX-2(MEC)KO tumors showed decreased expression of Ki67, a proliferation marker, as well as reduced VEGFA, its receptor VEGFR2, endothelial NOS and the vascular endothelial marker CD31, indicating reduced tumor vascularization. COX-2(MEC)KO tumors contained more CD4+ T helper (Th) cells and CD8+ cytotoxic immune cells (CTL) consistent with increased immune surveillance. The ratio of Th markers Tbet (Th1) to GATA3 (Th2) was higher, and levels of Retnla, a M2 macrophage marker, lower, in COX-2(MEC)KO tumor infiltrating leukocytes compared to WT, suggesting a prevalence of pro-immune Th1 over immune suppressive Th2 lymphocytes, and reduced macrophage polarization to the immune suppressive M2 phenotype. Enhanced immune surveillance in COX-2(MEC)KO tumors was coincident with increased intratumoral CXCL9, a T cell chemoattractant, and decreased expression of T lymphocyte co-inhibitory receptors CTLA4 and PD-1, as well as PD-L1, the ligand for PD-1. PD-L1 was also decreased in IFNγ-treated COX-2KD mouse mammary cancer cells in vitro and, compared to control cells, growth of COX-2KD cells as orthotopic tumors in immune competent mice was markedly suppressed. However, robust growth of COX-2KD tumor cells was evident when recipients were depleted of CD8+ cells.

CONCLUSIONS

The data strongly support that, in addition to its angiogenic function, tumor cell COX-2 suppresses intratumoral cytotoxic CD8+ immune cell function, possibly through upregulation of immune checkpoints, thereby contributing to tumor immune escape. COX-2 inhibition may be clinically useful to augment breast cancer immunotherapy.

The role of chemoattractant receptors in shaping the tumor microenvironment

Chemoattractant receptors are a family of seven transmembrane G protein coupled receptors (GPCRs) initially found to mediate the chemotaxis and activation of immune cells. During the past decades, the functions of these GPCRs have been discovered to not only regulate leukocyte trafficking and promote immune responses, but also play important roles in homeostasis, development, angiogenesis, and tumor progression. Accumulating evidence indicates that chemoattractant GPCRs and their ligands promote the progression of malignant tumors based on their capacity to orchestrate the infiltration of the tumor microenvironment by immune cells, endothelial cells, fibroblasts, and mesenchymal cells. This facilitates the interaction of tumor cells with host cells, tumor cells with tumor cells, and host cells with host cells to provide a basis for the expansion of established tumors and development of distant metastasis. In addition, many malignant tumors of the nonhematopoietic origin express multiple chemoattractant GPCRs that increase the invasiveness and metastasis of tumor cells. Therefore, GPCRs and their ligands constitute targets for the development of novel antitumor therapeutics.

Overexpression of SMARCE1 is associated with CD8+ T-cell infiltration in early stage ovarian cancer

T-lymphocyte infiltration in ovarian tumors has been linked to a favorable prognosis, hence, exploring the mechanism of T-cell recruitment in the tumor is warranted. We employed a differential expression analysis to identify genes over-expressed in early stage ovarian cancer samples that contained CD8 infiltrating T-lymphocytes. Among other genes, we discovered that TTF1, a regulator of ribosomal RNA gene expression, and SMARCE1, a factor associated with chromatin remodeling were overexpressed in first stage CD8+ ovarian tumors. TTF1 and SMARCE1 mRNA levels showed a strong correlation with the number of intra-tumoral CD8+ cells in ovarian tumors. Interestingly, forced overexpression of SMARCE1 in SKOV3 ovarian cancer cells resulted in secretion of IL8, MIP1b and RANTES chemokines in the supernatant and triggered chemotaxis of CD8+ lymphocytes in a cell culture assay. The potency of SMARCE1-mediated chemotaxis appeared comparable to that caused by the transfection of the CXCL9 gene, coding for a chemokine known to attract T-cells. Our analysis pinpoints TTF1 and SMARCE1 as genes potentially involved in cancer immunology. Since both TTF1 and SMARCE1 are involved in chromatin remodeling, our results imply an epigenetic regulatory mechanism for T-cell recruitment that invites deciphering.

Chitosan-based thermoreversible hydrogel as an in vitro tumor microenvironment for testing breast cancer therapies

Breast cancer is a major health problem for women worldwide. Although in vitro culture of established breast cancer cell lines is the most widely used model for preclinical assessment, it poorly represents the behavior of breast cancers in vivo. Acceleration of the development of effective therapeutic strategies requires a cost-efficient in vitro model that can more accurately resemble the in vivo tumor microenvironment. Here, we report the use of a thermoreversible poly(ethylene glycol)-g-chitosan hydrogel (PCgel) as an in vitro breast cancer model. We hypothesized that PCgel could provide a tumor microenvironment that promotes cultured cancer cells to a more malignant phenotype with drug and immune resistance. Traditional tissue culture plates and Matrigel were applied as controls in our studies. In vitro cellular proliferation and morphology, the secretion of angiogenesis-related growth factors and cytokines, and drug and immune resistance were assessed. Our results show that PCgel cultures promoted tumor aggregate formation, increased secretion of various angiogenesis- and metastasis-related growth factors and cytokines, and increased tumor cell resistance to chemotherapeutic drugs and immunotherapeutic T cells. This PCgel platform may offer a valuable strategy to bridge the gap between standard in vitro and costly animal studies for a wide variety of experimental designs.

Loss of Grainy head-like 1 is associated with disruption of the epidermal barrier and squamous cell carcinoma of the skin

The Grainyhead-like 1 (GRHL1) transcription factor regulates the expression of desmosomal cadherin desmoglein 1 (Dsg1) in suprabasal layers of the epidermis. As a consequence, the epidermis of Grhl1-null mice displays fewer desmosomes that are abnormal in structure. These mice also exhibit mild chronic skin barrier defects as evidenced by altered keratinocyte terminal differentiation, increased expression of inflammatory markers and infiltration of the skin by immune cells. Exposure of Grhl1^−/− mice to a standard chemical skin carcinogenesis protocol results in development of fewer papillomas than in wild type control animals, but with a rate of conversion to squamous cell carcinoma (SCC) that is strikingly higher than in normal littermates. The underlying molecular mechanism differs from mice with conditional ablation of a closely related Grhl family member, Grhl3, in the skin, which develop SCC due to the loss of expression of phosphatase and tensin homolog (PTEN) and activation of the phosphatidylinositol 3-kinase (PI3K)/AKT/mechanistic target of rapamycin (mTOR) signaling pathway.

Can pharmacological receptor tyrosine kinase inhibitors sensitize poor outcome breast tumors to immune-based therapies?

Receptor tyrosine kinases (RTKs) drive breast cancer progression, particularly in human epidermal growth factor receptor 2 and basal tumors, the two worst prognosis subtypes. Tumor cells recruit host stromal components, including immune cells, which strongly influence disease progression. This has been studied in human breast cancer and translated to murine models of breast cancer. Stromal immune components including cytotoxic T lymphocytes (CTLs) and natural killer cells, destroy cancer cells through a process termed immune surveillance. Unfortunately, clinically detectable tumors escape these immune protective effects through their ability to limit the infiltration, activation, and/or survival of CTLs in breast tumors. The immunosuppressed state of established tumors limits the success rate of immune-based therapies, and possibly other therapeutic modalities that depend on host immunity. Published studies demonstrate that RTKs facilitate breast cancer progression, in part, by establishing immune suppression. This raises the intriguing possibility that pharmacological RTK inhibitors may be exploited to sensitize breast cancer patients to immune-based therapies.

Pharmacological characterization of a small-molecule agonist for the chemokine receptor CXCR3

BACKGROUND AND PURPOSE

The chemokine receptor CXCR3 is a GPCR found predominantly on activated T cells. CXCR3 is activated by three endogenous peptides; CXCL9, CXCL10 and CXCL11. Recently, a small-molecule agonist, VUF10661, has been reported in the literature and synthesized in our laboratory. The aim of the present study was to provide a detailed pharmacological characterization of VUF10661 by comparing its effects with those of CXCL11.

EXPERIMENTAL APPROACH

Agonistic properties of VUF10661 were assessed in a chemotaxis assay with murine L1.2 cells transiently transfected with cDNA encoding the human CXCR3 receptor and in binding studies, with [(125)I]-CXCL10 and [(125)I]-CXCL11, on membrane preparations from HEK293 cells stably expressing CXCR3. [(35)S]-GTPγS binding was used to determine its potency to induce CXCR3-mediated G protein activation and BRET-based assays to investigate its effects on intracellular cAMP levels and β-arrestin recruitment.

KEY RESULTS

VUF10661 acted as a partial agonist in CXCR3-mediated chemotaxis, bound to CXCR3 in an allosteric fashion in ligand binding assays and activated G(i) proteins with the same efficacy as CXCL11 in the [(35)S]-GTPγS binding and cAMP assay, while it recruited more β-arrestin1 and β-arrestin2 to CXCR3 receptors than the chemokine.

CONCLUSIONS AND IMPLICATIONS

VUF10661, like CXCL11, activates both G protein-dependent and -independent signalling via the CXCR3 receptor, but probably exerts its effects from an allosteric binding site that is different from that for CXCL11. It could stabilize different receptor and/or β-arrestin conformations leading to differences in functional output. Such ligand-biased signalling might offer interesting options for the therapeutic use of CXCR3 agonists.

Further evidence for a role of tumor CD200 expression in breast cancer metastasis: decreased metastasis in CD200R1KO mice or using CD200-silenced EMT6

Previous studies reported that CD200 expression on cells of the transplantable EMT6 mouse breast cancer line was increased during growth in immunocompetent mice. Low levels of expression persisted in NOD-SCID.IL-2(γr-/-) mice or mice with generalized over-expression of a CD200 transgene (CD200(tg) mice), despite the faster tumor growth in both of these latter strains. We also showed that CD200 expression (by the host and/or tumor cells) led to increased seeding of tumor cells to DLN in immunocompromised (CD200(tg) or NOD-SCID.IL-2(γr-/-)) vs immunocompetent mice, using limiting dilution cloning of tumor cells from DLN (vs contralateral lymph nodes, CLN). Evidence for an important role for CD200 expression in this increased metastasis came from the observation that neutralization of CD200 by anti-CD200mAbs decreased tumor metastasis and increased levels of cytotoxic anti-tumor immune cells in DLN. In the current studies, we have extended these observations by exploring tumor growth/metastasis in CD200R1 KO mice in which we have previously shown, in a transplant model, that expression of CD200 fails to deliver an immunosuppressive signal. In addition, we have studied local and metastatic growth in healthy control mice of EMT6 tumor cells stably transduced with shRNA able to silence CD200 expression. In both scenarios, decreased metastasis was observed, with increased immunity to EMT6 detected by cytotoxicity assays. In addition, adoptive transfer of DLN to control mice attenuated EMT6 metastases implying a potential therapeutic benefit from neutralizing CD200 expression in breast cancer.

NLRP3 suppresses NK cell-mediated responses to carcinogen-induced tumors and metastases

The NLRP3 inflammasome acts as a danger signal sensor that triggers and coordinates the inflammatory response upon infectious insults or tissue injury and damage. However, the role of the NLRP3 inflammasome in natural killer (NK) cell-mediated control of tumor immunity is poorly understood. Here, we show in a model of chemical-induced carcinogenesis and a series of experimental and spontaneous metastases models that mice lacking NLRP3 display significantly reduced tumor burden than control wild-type (WT) mice. The suppression of spontaneous and experimental tumor metastases and methylcholanthrene (MCA)-induced sarcomas in mice deficient for NLRP3 was NK cell and IFN-γ-dependent. Focusing on the amenable B16F10 experimental lung metastases model, we determined that expression of NLRP3 in bone marrow-derived cells was necessary for optimal tumor metastasis. Tumor-driven expansion of CD11b(+)Gr-1(intermediate) (Gr-1(int)) myeloid cells within the lung tumor microenvironment of NLRP3(-/-) mice was coincident with increased lung infiltrating activated NK cells and an enhanced antimetastatic response. The CD11b(+)Gr-1(int) myeloid cells displayed a unique cell surface phenotype and were characterized by their elevated production of CCL5 and CXCL9 chemokines. Adoptive transfer of this population into WT mice enhanced NK cell numbers in, and suppression of, B16F10 lung metastases. Together, these data suggested that NLRP3 is an important suppressor of NK cell-mediated control of carcinogenesis and metastases and identify CD11b(+)Gr-1(int) myeloid cells that promote NK cell antimetastatic function.

The emerging role of CXC chemokines and their receptors in cancer

Chemokines and their receptors have a multifaceted role in tumor biology and are implicated in nearly all aspects of cancer growth, survival and dissemination. Modulation of the interaction between chemokines and their cell surface receptor is, therefore, a promising area for the development of new cancer medicines. In this review, we look at the compelling evidence that is emerging to support targeting CXC chemokines, also known as family α chemokines, as novel therapeutic strategies in the treatment of cancer.

Homeobox D10 gene, a candidate tumor suppressor, is downregulated through promoter hypermethylation and associated with gastric carcinogenesis

Homeobox D10 (HoxD10 ) gene plays a critical role in cell differentiation and morphogenesis during development. However, the function of HoxD10 in tumor progression remains largely unknown. We demonstrate that the expression of HoxD10 is commonly downregulated in gastric cancer tissues (n = 33) and cell lines (n = 8) relative to normal stomach tissues. Functionally, reexpression of HoxD10 results in significant inhibition of cell survival, induction of cell apoptosis, and impairment of cell migration and invasion. Moreover, ectopic expression of HoxD10 suppresses gastric tumor growth in a mouse xenograft model. To identify target candidates of HoxD10, we performed cDNA microarray and showed that HoxD10 regulates multiple downstream genes including IGFBP3. Reintroduction of HoxD10 transcriptionally upregulates IGFBP3, activates caspase 3 and caspase 8, and subsequently induces cell apoptosis. Methylation specific PCR revealed that HoxD10 promoter DNA was hypermethylated in gastric cancer cell lines. Additionally, 5-aza demethylation treatment could transiently reactivate the expression of HoxD10 in gastric cancer cells. HoxD10 promoter methylation frequently was detected in gastric cancer tissues obtained from endoscopic biopsies (85.7%, 24/28) and surgically resected samples (82.6%, 57/69). Intestinal metaplasia tissues showed a 60% methylation rate (18/30), but no detectable methylation in normal stomach tissues (0%, 0/10). Taken together, our results suggest that HoxD10 functions as a candidate tumor suppressor in gastric cancer, which is inactivated through promoter hypermethylation.

Modulation of CXCR3 ligand secretion by prostaglandin E2 and cyclooxygenase inhibitors in human breast cancer

Introduction

In murine breast cancer models, the two interferon-gamma (IFN-γ) inducible chemokines and CXC-chemokine receptor 3 (CXCR3) receptor ligands, monokine induced by γ-interferon (CXCL9) and interferon-γ-inducible protein-10 (CXCL10) impair tumor growth and metastasis formation through recruitment of natural killer (NK) cells and tumor-suppressive T lymphocytes. In human breast cancer, CXCL9 mRNA overexpression correlates with the number of tumor infiltrating lymphocytes and predicts response to different chemotherapeutic regimens. Raising the intratumoral CXCR3 ligand concentration is therefore a possible way to enhance immune intervention in breast cancer. Little is known, however, about expression levels and regulation of these chemokines in human breast cancer. Since the inhibition of cyclooxygenases (COX) has been shown to reduce tumor growth and incidence of metastases in a lymphocytic and IFN-γ dependent manner, we argued that COX isoenzymes are a pharmacologic target to increase intratumoral CXCR3 ligand concentration in human breast cancer.

Methods

CXCL9 was visualized in breast cancer specimens by immunohistochemistry, expression levels of CXCL9 and cyclooxygenases were determined by ELISA and western blotting, respectively. For regulation studies, Michigan Cancer Foundation-7 (MCF-7) and M.D. Anderson - Metastatic Breast 231 (MDA-MB 231) breast cancer cells were stimulated with IFN-γ with or without prostaglandin E₂ (PGE₂) or COX inhibitors (indomethacin, acetylsalicylic acid (ASA), celecoxib). CXCR3 ligand release from cells was measured by ELISA.

Results

Within the tumor microenvironment, cancer cells are the major source of CXCL9. PGE₂ impairs IFN-γ mediated CXCL9 and CXCL10 release from MCF-7 and MDA-MB 231 cells, and inhibition of endogenous cyclooxygenases by indomethacin or ASA correspondingly increases this secretion. Otherwise, high concentrations of the Cyclooxygenase-2 (COX-2) specific antagonist celecoxib have opposite effects and impair CXCL9 and CXCL10 release. In human breast cancer tissue specimens there is an inverse correlation between COX-2 overexpression and CXCL9 concentration, suggesting that the observed in vitro effects are of importance in vivo as well.

Conclusions

Suppressing endogenous PGE₂ synthesis by cyclooxygenase inhibition increases CXCL9 and CXCL10 release from breast cancer cells and is therefore a pharmacologic candidate to enhance intratumoral immune infiltration. Yet, to this end the unselective COX inhibitors ASA and indomethacin seem preferable to celecoxib that at higher concentrations reduces CXCR3 ligand release most probably due to COX independent mechanisms.