Rejection of metastatic 4T1 breast cancer by attenuation of Treg cells in combination with immune stimulation

Granzyme-targeting quenched activity-based probes for assessing tumor response to immunotherapy

Molecular imaging of immune activation holds tremendous potential for the development of novel immunotherapy. In particular, chemical probes capable of detecting immune responses before changes in tumor size occur can guide early therapeutic strategies. Here, we present quenched activity-based probes targeting granzymes as a biomarker of antitumor immunity. Through optimization of peptide recognition element and functional chemical warhead, we have developed an optical imaging probe Cy5-IEPCyaPhP-QSY21, which rapidly reacts with GzmB at substoichiometric concentrations and enables efficient, selective labeling of the active enzyme in a complex proteome. With high specificity and minimal background signal, this probe produces GzmB-induced near-infrared fluorescence signals in the tumors of living mice shortly after injection. Both in vivo and ex vivo fluorescence signals correlate with GzmB expression and activity, and the population of CD8+ cells in tumor tissues. Moreover, it demonstrates the potential to track tumor response to immunotherapy. Thus, this study offers a chemical tool for assessing immune-mediated anticancer activity using noninvasive optical imaging.

Engineering Modular Peptide Nanoparticles for Ferroptosis-Enhanced Tumor Immunotherapy

Indoleamine 2,3-dioxygenase 1 (IDO1) inhibitors are promising for treating tumors but have limited efficacy due to the immunosuppressive tumor microenvironment. In this study, we develop an orchestrated nanoparticle system using modular peptide assemblies, where the co-assembled sequences are designed for the specific binding to the hydrophobic and hydrophilic domains, guiding the assembly process and enabling the customization of nanoparticle properties. We exploit the modularity of this platform to integrate a hydrophobic ferroptosis precursor, an IDO1 inhibitor, and a hydrophilic peptidic PD-L1 antagonist for optimizing therapeutic outcomes through ferroptosis-enhanced tumor immunotherapy. The resulting nanoparticles induce immunogenic ferroptosis, enhance the intratumoral function of T lymphocytes, suppress regulatory T cells, and effectively modulate the immunosuppressive tumor microenvironment, thereby facilitating regression of tumor growth. This work provides a modular peptide-based nanoparticle engineering strategy and holds significant potential for advancing cancer treatment.

Inflammation-Triggering Engineered Macrophages (MacTriggers) Enhance Reactivity of Immune Checkpoint Inhibitor Only in Tumor Tissues

Background: We have previously reported engineered macrophages (MacTriggers) that can accelerate the release of tumor necrosis factor-α in response to M2 polarization. MacTriggers are characterized by two original characteristics of macrophages: (1) migration to tumors; and (2) polarization to the M2 phenotype in tumors. Intravenously administered MacTriggers efficiently accumulated in the tumors and induced tumor-specific inflammation. This study reports a novel methodology for enhancing the anti-tumor effects of immune checkpoint inhibitors (ICIs). Results: In this study, we newly found that the intravenously administered MacTriggers in BALB/c mouse models upregulated the expression levels of immune checkpoint proteins, such as programmed cell death (PD)-1 in CD8+ T cells and PD-ligand 1 (PD-L1) in cancer cells and macrophages. Consequently, in two ICI-resistant tumor-inoculated mouse models, the combined administration of MacTrigger and anti-PD-1 antibody (aPD-1) synergistically inhibited tumor growth, whereas monotherapy with aPD-1 did not exhibit anti-tumor effects. This synergistic effect was mainly from aPD-1 enhancing the tumor-attacking ability of CD8+ T cells, which could infiltrate into the tumors following MacTrigger treatment. Importantly, no side effects were observed in normal tissues, particularly in the liver and spleen, indicating that the MacTriggers did not enhance the aPD-1 reactivity in normal tissues. This specificity was from the MacTriggers not polarizing to the M2 phenotype in normal tissues, thereby avoiding inflammation and increased PD-1/PD-L1 expression. MacTriggers could enhance aPD-1 reactivity only in tumors following tumor-specific inflammation induction. Conclusions: Our findings suggest that the MacTrigger and aPD-1 combination therapy is a novel approach for potentially overcoming the current low ICI response rates while avoiding side effects.

High-Affinity Superantigen-Based Trifunctional Immune Cell Engager Synergizes NK and T Cell Activation for Tumor Suppression

The development of immune cell engagers (ICEs) can be limited by logistical and functional restrictions associated with fusion protein designs, thus limiting immune cell recruitment to solid tumors. Herein, a high affinity superantigen-based multivalent ICE is developed for simultaneous activation and recruitment of NK and T cells for tumor treatment. Yeast library-based directed evolution is adopted to identify superantigen variants possessing enhanced binding affinity to immunoreceptors expressed on human T cells and NK cells. High-affinity superantigens exhibiting improved immune-stimulatory activities are then incorporated into a superantigen-based tri-functional yeast-display-enhanced multivalent immune cell engager (STYMIE), which is functionalized with a nanobody, a Neo-2/15 cytokine, and an Fc domain for tumor targeting, immune stimulation, and prolonged circulation, respectively. Intravenous administration of STYMIE enhances NK and T cell recruitment into solid tumors, leading to enhanced inhibition in multiple tumor models. The study offers design principles for multifunctional ICEs.

The temporal progression of lung immune remodeling during breast cancer metastasis

Tumor metastasis requires systemic remodeling of distant organ microenvironments that impacts immune cell phenotypes, population structure, and intercellular communication. However, our understanding of immune phenotypic dynamics in the metastatic niche remains incomplete. Here, we longitudinally assayed lung immune transcriptional profiles in the polyomavirus middle T antigen (PyMT) and 4T1 metastatic breast cancer models from primary tumorigenesis, through pre-metastatic niche formation, to the final stages of metastatic outgrowth at single-cell resolution. Computational analyses of these data revealed a TLR-NFκB inflammatory program enacted by both peripherally derived and tissue-resident myeloid cells that correlated with pre-metastatic niche formation and mirrored CD14+ "activated" myeloid cells in the primary tumor. Moreover, we observed that primary tumor and metastatic niche natural killer (NK) cells are differentially regulated in mice and human patient samples, with the metastatic niche featuring elevated cytotoxic NK cell proportions. Finally, we identified cell-type-specific dynamic regulation of IGF1 and CCL6 signaling during metastatic progression that represents anti-metastatic immunotherapy candidate pathways.

Intratumoral delivery of immunotherapy to treat breast cancer: current development in clinical and preclinical studies

Breast cancer poses one of the largest threats to women's health. Treatment continues to improve for all the subtypes of breast cancer, but some subtypes, such as triple negative breast cancer, still present a significant treatment challenge. Additionally, metastasis and local recurrence are two prevalent problems in breast cancer treatment. A newer type of therapy, immunotherapy, may offer alternatives to traditional treatments for difficult-to-treat subtypes. Immunotherapy engages the host's immune system to eradicate disease, with the potential to induce long-lasting, durable responses. However, systemic immunotherapy is only approved in a limited number of indications, and it benefits only a minority of patients. Furthermore, immune related toxicities following systemic administration of potent immunomodulators limit dosing and, consequently, efficacy. To address these safety considerations and improve treatment efficacy, interest in local delivery at the site of the tumor has increased. Numerous intratumorally delivered immunotherapeutics have been and are being explored clinically and preclinically, including monoclonal antibodies, cellular therapies, viruses, nucleic acids, cytokines, innate immune agonists, and bacteria. This review summarizes the current and past intratumoral immunotherapy clinical landscape in breast cancer as well as current progress that has been made in preclinical studies, with a focus on delivery parameters and considerations.

Combination of verteporfin-photodynamic therapy with 5-aza-2'-deoxycytidine enhances the anti-tumour immune response in triple negative breast cancer

Introduction

Triple negative breast cancer (TNBC) is a subtype of breast cancer characterised by its high tumourigenic, invasive, and immunosuppressive nature. Photodynamic therapy (PDT) is a focal therapy that uses light to activate a photosensitizing agent and induce a cytotoxic effect. 5-aza-2'-deoxycytidine (5-ADC) is a clinically approved immunomodulatory chemotherapy agent. The mechanism of the combination therapy using PDT and 5-ADC in evoking an anti-tumour response is not fully understood.

Methods

The present study examined whether a single dose of 5-ADC enhances the cytotoxic and anti-tumour immune effect of low dose PDT with verteporfin as the photosensitiser in a TNBC orthotopic syngeneic murine model, using the triple negative murine mammary tumour cell line 4T1. Histopathology analysis, digital pathology and immunohistochemistry of treated tumours and distant sites were assessed. Flow cytometry of splenic and breast tissue was used to identify T cell populations. Bioinformatics were used to identify tumour immune microenvironments related to TNBC patients.

Results

Functional experiments showed that PDT was most effective when used in combination with 5-ADC to optimize its efficacy. 5-ADC/PDT combination therapy elicited a synergistic effect in vitro and was significantly more cytotoxic than monotherapies on 4T1 tumour cells. For tumour therapy, all types of treatments demonstrated histopathologically defined margins of necrosis, increased T cell expression in the spleen with absence of metastases or distant tissue destruction. Flow cytometry and digital pathology results showed significant increases in CD8 expressing cells with all treatments, whereas only the 5-ADC/PDT combination therapy showed increase in CD4 expression. Bioinformatics analysis of in silico publicly available TNBC data identified BCL3 and BCL2 as well as the following anti-tumour immune response biomarkers as significantly altered in TNBC compared to other breast cancer subtypes: GZMA, PRF1, CXCL1, CCL2, CCL4, and CCL5. Interestingly, molecular biomarker assays showed increase in anti-tumour response genes after treatment. The results showed concomitant increase in BCL3, with decrease in BCL2 expression in TNBC treatment. In addition, the treatments showed decrease in PRF1, CCL2, CCL4, and CCL5 genes with 5-ADC and 5-ADC/PDT treatment in both spleen and breast tissue, with the latter showing the most decrease.

Discussion

To our knowledge, this is the first study that shows which of the innate and adaptive immune biomarkers are activated during PDT related treatment of the TNBC 4T1 mouse models. The results also indicate that some of the immune response biomarkers can be used to monitor the effectiveness of PDT treatment in TNBC murine model warranting further investigation in human subjects.

Dual Functions of T Lymphocytes in Breast Carcinoma: From Immune Protection to Orchestrating Tumor Progression and Metastasis

Breast cancer (BC) is the most common cancer type in women and the second leading cause of death. Despite recent advances, the mortality rate of BC is still high, highlighting a need to develop new treatment strategies including the modulation of the immune system and immunotherapies. In this regard, understanding the complex function of the involved immune cells and their crosstalk with tumor cells is of great importance. T-cells are recognized as the most important cells in the tumor microenvironment and are divided into several subtypes including helper, cytotoxic, and regulatory T-cells according to their transcription factors, markers, and functions. This article attempts to provide a comprehensive review of the role of T-cell subsets in the prognosis and treatment of patients with BC, and crosstalk between tumor cells and T-cells. The literature overwhelmingly contains controversial findings mainly due to the plasticity of T-cell subsets within the inflammatory conditions and the use of different panels for their phenotyping. However, investigating the role of T-cells in BC immunity depends on a variety of factors including tumor types or subtypes, the stage of the disease, the localization of the cells in the tumor tissue and the presence of different cells or cytokines.

Regression and Eradication of Triple-Negative Breast Carcinoma in 4T1 Mouse Model by Combination Immunotherapies

Triple-negative breast carcinoma (TNBC) is one of the most aggressive types of solid-organ cancers. While immune checkpoint blockade (ICB) therapy has significantly improved outcomes in certain types of solid-organ cancers, patients with immunologically cold TNBC are afforded only a modest gain in survival by the addition of ICB to systemic chemotherapy. Thus, it is urgently needed to develop novel effective therapeutic approaches for TNBC. Utilizing the 4T1 murine model of TNBC, we developed a novel combination immunotherapeutic regimen consisting of intratumoral delivery of high-mobility group nucleosome binding protein 1 (HMGN1), TLR2/6 ligand fibroblast-stimulating lipopeptide (FSL-1), TLR7/8 agonist (R848/resiquimod), and CTLA-4 blockade. We also investigated the effect of adding SX682, a small-molecule inhibitor of CXCR1/2 known to reduce MDSC trafficking to tumor microenvironment, to our therapeutic approach. 4T1-bearing mice responded with significant tumor regression and tumor elimination to our therapeutic combination regimen. Mice with complete tumor regressions did not recur and became long-term survivors. Treatment with HMGN1, FSL-1, R848, and anti-CTLA4 antibody increased the number of infiltrating CD4+ and CD8+ effector/memory T cells in both tumors and draining lymph nodes and triggered the generation of 4T1-specific cytotoxic T lymphocytes (CTLs) in the draining lymph nodes. Thus, we developed a potentially curative immunotherapeutic regimen consisting of HMGN1, FSL-1, R848, plus a checkpoint inhibitor for TNBC, which does not rely on the administration of chemotherapy, radiation, or exogenous tumor-associated antigen(s).

Application of a count data model to evaluate the anti-metastatic efficacy of QAP14 in 4T1 breast cancer allografts

Dopamine D1 receptor (D1DR) is proved to be a promising target to prevent tumor metastasis, and our previous studies showed that QAP14, a potent anti-cancer agent, exerted inhibitory effect on lung metastasis via D1DR activation. Therefore, the purpose of the study was to establish count data models to quantitatively characterize the disease progression of lung metastasis and assess the anti-metastatic effect of QAP14. Data of metastatic progression were collected in 4T1 tumor-bearing mice. Generalized Poisson distribution best described the variability of metastasis counts among the individuals. An empirical PK/PD model was developed to establish mathematical relationships between steady plasma concentrations of QAP14 and metastasis growth dynamics. The latency period of metastasis was estimated to be 12 days after tumor implantation. Our model structure also fitted well to other D1DR agonists (fenoldopam and l-stepholidine) which had inhibitory impact on breast cancer lung metastasis likewise. QAP14 40 mg/kg showed the best inhibitory efficacy, for it provided the longest prolongation of metastasis-free periods compared with fenoldopam or l-stepholidine. This study provides a quantitative method to describe the lung metastasis progression of 4T1 allografts, as well as an alternative PD model structure to evaluate anti-metastatic efficacy.

Gaseous nitric oxide tumor ablation induces an anti-tumor abscopal effect

BACKGROUND

In-situ tumor ablation provides the immune system with the appropriate antigens to induce anti-tumor immunity. Here, we present an innovative technique for generating anti-tumor immunity by delivering exogenous ultra-high concentration (> 10,000 ppm) gaseous nitric oxide (UHCgNO) intratumorally.

METHODS

The capability of UHCgNO to induce apoptosis was tested in vitro in mouse colon (CT26), breast (4T1) and Lewis lung carcinoma (LLC-1) cancer cell lines. In vivo, UHCgNO was studied by treating CT26 tumor-bearing mice in-situ and assessing the immune response using a Challenge assay.

RESULTS

Exposing CT26, 4T1 and LLC-1 cell lines to UHCgNO for 10 s-2.5 min induced cellular apoptosis 24 h after exposure. Treating CT26 tumors in-situ with UHCgNO followed by surgical resection 14 days later resulted in a significant secondary anti-tumor effect in vivo. 100% of tumor-bearing mice treated with 50,000 ppm UHCgNO and 64% of mice treated with 20,000 ppm UHCgNO rejected a second tumor inoculation, compared to 0% in the naive control for 70 days. Additionally, more dendrocytes infiltrated the tumor 14 days post UHCgNO treatment versus the nitrogen control. Moreover, T-cell penetration into the primary tumor was observed in a dose-dependent manner. Systemic increases in T- and B-cells were seen in UHCgNO-treated mice compared to nitrogen control. Furthermore, polymorphonuclear-myeloid-derived suppressor cells were downregulated in the spleen in the UHCgNO-treated groups.

CONCLUSIONS

Taken together, our data demonstrate that UHCgNO followed by the surgical removal of the primary tumor 14 days later induces a strong and potent anti-tumor response.

Redirecting host preexisting influenza A virus immunity for cancer immunotherapy

We tested the concept that host preexisting influenza A virus immunity can be redirected to inhibit tumor growth and metastasis through systemic administration of influenza A virus–related peptides to targeted tumors. Mice infected with influenza A virus strain A/Puerto Rico/8/34 (PR8) were used as a model of a host with preexisting viral immunity. The extent to which preexisting influenza A immunity in PR8-immunized mice can be redirected to inhibit tumor growth and metastasis was first examined by ectopic expression of influenza A nucleoprotein (NP) and hemagglutinin (HA) in syngeneic mammary tumor cells via lentiviral transduction. Then, the feasibility of implementing this strategy using a systemic therapy approach was assessed by systemic delivery of major histocompatibility complex class I (MHC-I)-compatible peptides to targeted mammary tumors overexpressing human epidermal growth factor receptor-2 (HER2) in mice using a novel HER2-targeting single-lipid nanoparticle (SLNP). Our results show that preexisting influenza A immunity in PR8-immunized mice could be quickly redirected to syngeneic tumors expressing influenza A NP and HA, leading to strong inhibition of tumor growth and metastasis and improvement of survival compared to the findings in antigen-naïve control mice. MHC-I-compatible peptides could be delivered to targeted mammary tumors in mice using the HER2-targeting SLNP for antigen presentation, which subsequently redirected preexisting influenza A immunity to the tumors to exert antitumor activities. In conclusion, preexisting influenza A immunity can be repurposed for cancer immunotherapy through systemic delivery of influenza A–related peptides to targeted tumors. Further development of the strategy for clinical translation is warranted.

High-dose IL-2/CD25 fusion protein amplifies vaccine-induced CD4+ and CD8+ neoantigen-specific T cells to promote antitumor immunity

BACKGROUND

Immunization with tumor neoantigens is a promising vaccine approach to promote antitumor immunity due to their high immunogenicity, lack of expression in normal tissue, and preferential induction of tumor neoantigen-specific T cells, which are central mediators of the anti-cancer response. A drawback to targeting tumor neoantigen-specific T cells is that these cells are found at a low frequency in patients with cancer, limiting their therapeutic benefit. Interleukin-2 (IL-2) promotes expansion and persistence of tumor-reactive T cells. However, its clinical use has been hampered by toxicities arising from its multiple cellular targets. Thus, new engineered IL-2 receptor (IL-2R) agonists with distinctive cell type selectivity have been designed to harness the potential of IL-2 for tumor immunotherapy.

METHODS

We investigated the potential to amplify neoantigen-specific CD4⁺ and CD8⁺ T cell immune responses to promote antitumor immunity through vaccination with tumor neoantigens. Following T cell receptor (TCR)-mediated induction of the high-affinity IL-2R on these T cells, amplification of the neoantigen-specific T cell response was achieved using a high dose of the mouse IL-2/CD25 (mIL-2/CD25) fusion protein, an IL-2R agonist with more favorable pharmacokinetics and pharmacodynamics than IL-2 and selectivity toward the high-affinity IL-2R.

RESULTS

Administration of a high dose of mIL-2/CD25 shortly after antigen-dependent induction of the high-affinity IL-2R amplified the numbers and function of TCR transgenic tumor-reactive tyrosinase-related protein-1 (TRP-1) CD4⁺ T cells, leading to antitumor immunity to B16-F10 melanoma. This approach was adapted to amplify endogenous polyclonal B16-F10 neoantigen-specific T cells. Maximal expansion of these cells required prime/boost neoantigen vaccinations, where mIL-2/CD25 was optimal when administered only after the boosting steps. The ensuing mIL-2/CD25-driven immune response supported antitumor immunity to B16-F10 and was more effective than treatment with a similar amount of IL-2. Optimal antitumor effects required amplification of CD4⁺ and CD8⁺ neoantigen-specific T cells. High-dose mIL-2/CD25 supported a tumor microenvironment with higher numbers of CD4⁺ and CD8⁺ T effectors cells with increased granzyme B expression and importantly a more robust expansion of neoantigen-specific T cells.

CONCLUSION

These results indicate that neoantigen-based vaccines are optimized by potentiating IL-2R signaling in CD4⁺ and CD8⁺ neoantigen-reactive T cells by using high-dose mIL-2/CD25, leading to more effective tumor clearance.

Emerging strategies for treating metastasis

The systemic spread of tumor cells is the ultimate cause of the majority of deaths from cancer, yet few successful therapeutic strategies have emerged to specifically target metastasis. Here we discuss recent advances in our understanding of tumor-intrinsic pathways driving metastatic colonization and therapeutic resistance, as well as immune activating strategies to target metastatic disease. We focus on therapeutically exploitable mechanisms, promising strategies in preclinical and clinical development, and emerging areas with potential to become innovative treatments.

FAP-Targeted Photodynamic Therapy Mediated by Ferritin Nanoparticles Elicits an Immune Response against Cancer Cells and Cancer Associated Fibroblasts

Cancer-associated fibroblasts (CAFs) are present in many types of tumors and play a pivotal role in tumor progression and immunosuppression. Fibroblast-activation protein (FAP), which is overexpressed on CAFs, has been indicated as a universal tumor target. However, FAP expression is not restricted to tumors, and systemic treatment against FAP often causes severe side effects. To solve this problem, a photodynamic therapy (PDT) approach was developed based on ZnF16Pc (a photosensitizer)-loaded and FAP-specific single chain variable fragment (scFv)-conjugated apoferritin nanoparticles, or αFAP-Z@FRT. αFAP-Z@FRT PDT efficiently eradicates CAFs in tumors without inducing systemic toxicity. When tested in murine 4T1 models, the PDT treatment elicits anti-cancer immunity, causing suppression of both primary and distant tumors, i.e. abscopal effect. Treatment efficacy is enhanced when αFAP-Z@FRT PDT is used in combination with anti-PD1 antibodies. Interestingly, it is found that the PDT treatment not only elicits a cellular immunity against cancer cells, but also stimulates an anti-CAFs immunity. This is supported by an adoptive cell transfer study, where T cells taken from 4T1-tumor-bearing animals treated with αFAP PDT retard the growth of A549 tumors established on nude mice. Overall, our approach is unique for permitting site-specific eradication of CAFs and inducing a broad spectrum anti-cancer immunity.

Macrophages mediate colon carcinoma cell adhesion in the rat liver after exposure to lipopolysaccharide

The surgical resection of primary colorectal cancer is associated with an enhanced risk of liver metastases. Moreover, bacterial translocation or anastomic leakage during resection has been shown to correlate with a poor long-term surgical outcome, suggesting that bacterial products may contribute to the formation of metastases. Driven by these premises, we investigated the role of the bacterial product lipopolysaccharide (LPS) in the generation of liver metastases. Intraperitoneal injection of LPS led to enhanced tumor-cell adhesion to the rat liver as early as 1.5 h post-administration. Furthermore, a rapid loss of the expression of the tight junction protein zonula occludens-1 (ZO-1) was observed, suggesting that LPS disrupts the integrity of the microvasculature. LPS addition to endothelial-macrophage co-cultures damaged endothelial monolayers and caused the formation of intercellular gaps, which was accompanied by increased tumor-cell adhesion. These results suggest that macrophages are involved in the endothelial damage resulting from exposure to LPS. Interestingly, the expression levels of of ZO-1 were not affected by LPS treatment in rats in which liver macrophages had been depleted as well as in rats that had been treated with a reactive oxygen species (ROS) scavenger. In both settings, decreased tumor-cell adhesion was observed. Taken together, our findings indicate that LPS induces ROS release by macrophages, resulting in the damage of the vascular lining of the liver and hence allowing increased tumor-cell adherence. Thus, peri-operative treatments that prevent the activation of macrophages and—as a consequence—limit endothelial damage and tumor-cell adhesion may significantly improve the long-term outcome of cancer patients undergoing surgical tumor resection.

CaCO3-Assisted Preparation of pH-Responsive Immune-Modulating Nanoparticles for Augmented Chemo-Immunotherapy

Due to the negative roles of tumor microenvironment (TME) in compromising therapeutic responses of various cancer therapies, it is expected that modulation of TME may be able to enhance the therapeutic responses during cancer treatment. Herein, we develop a concise strategy to prepare pH-responsive nanoparticles via the CaCO₃-assisted double emulsion method, thereby enabling effective co-encapsulation of both doxorubicin (DOX), an immunogenic cell death (ICD) inducer, and alkylated NLG919 (aNLG919), an inhibitor of indoleamine 2,3-dioxygenase 1 (IDO1). The obtained DOX/aNLG919-loaded CaCO₃ nanoparticles (DNCaNPs) are able to cause effective ICD of cancer cells and at the same time restrict the production of immunosuppressive kynurenine by inhibiting IDO1. Upon intravenous injection, such DNCaNPs show efficient tumor accumulation, improved tumor penetration of therapeutics and neutralization of acidic TME. As a result, those DNCaNPs can elicit effective anti-tumor immune responses featured in increased density of tumor-infiltrating CD8⁺ cytotoxic T cells as well as depletion of immunosuppressive regulatory T cells (Tregs), thus effectively suppressing the growth of subcutaneous CT26 and orthotopic 4T1 tumors on the Balb/c mice through combined chemotherapy & immunotherapy. This study presents a compendious strategy for construction of pH-responsive nanoparticles, endowing significantly enhanced chemo-immunotherapy of cancer by overcoming the immunosuppressive TME.

Anti-metastatic action of an N 4-aryl substituted thiosemicarbazone on advanced triple negative breast cancer

Purpose

Advanced triple negative breast cancer (ATNBC) is defined by a lack of expression of hormones receptors as well as HER2/neu and its high probability of visceral metastasis. This pathology is associated with a poor prognosis. Previously, we found that T2, an N⁴-arylsubstituted thiosemicarbazone (N⁴-TSC), had cytotoxic effect on human breast cancer cells lines. Hence, in this study, we investigated the anti-metastasic action of T2 on ATNBC.

Methods

In order to deepen T2 action mode on ATNBC, we first confirmed T2 cytotoxicity on a panel of TNBC cells and then continued studying T2 effects in vitro an in vivo on the syngeneic 4T1 mouse model.

Results

We found that T2 had a cytotoxic effect comparable to chemotherapeutics used in present treatment schemes for ATNBC. T2 treatment not only induced apoptosis, but it also down-modulated 4T1 invasive and metastatic-associated capacities, such as clonogenicity, migration and metallo-proteases activity. Moreover, this agent reduced the number of 4T1 cancer stem cells. Finally, T2 treatment induced a more differentiated cell phenotype and the overexpression of the metastasis suppressor gene NDRG-1. In vivo assays showed that T2 reduced tumor burden, down modulated local tumor invasion and significantly reduced the number of lung metastases in the 4T1 advanced TNBC murine model, while the compound did not exhibit intolerable toxicity.

Conclusion

This study provided evidence that T2 not only exerted an anti-tumor activity but it also showed anti-invasive and anti-metastatic actions on ATNBC in vivo and in vitro, suggesting that T2 could be considered as a promising therapy that deserves further analysis.

Regulatory T cells in breast cancer as a potent anti-cancer therapeutic target

Despite marked advances in treatment approaches, breast cancer is still going to be more prevalent, worldwide. High levels of regulatory T (Treg) cells have repeatedly been demonstrated in circulation, lymph nodes, and tumor samples from patients with various cancer types. The transcription factor Forkhead box protein 3 (Foxp3)-expressing Treg cells have the high suppressive potential of the immune system and are fundamental in preserving immune homeostasis and self-tolerance. However, they enhance tumor development by curbing efficient anti-tumor immune mechanisms in malignancies. Moreover, the accumulation of Treg cells in breast tumors is related to the short overall survival of patients. Treg cell frequency has been applied as an independent predicting factor to diagnose patients with a high risk of relapse. Pulling out all populations of Treg cells to promote the efficacy of anticancer treatment methods may potentially lead to hazardous autoimmune disorders. Thus, realizing the exact structure of tumor-infiltrating Treg cells is pivotal to efficiently target Treg cells in tumors. There are exclusive and non-exclusive approaches to lower down and degrade the number/function of Treg cells. These approaches can include inhibiting tumoral migration, depletion, interference with function, and utilizing T cell plasticity. This review article attempts to clarify the implications concerning the involvement of Treg cells in breast cancer progression and discuss the current approaches in the treatment of this cancer via modulation of Treg cells function.

Milk fermented by Lactobacillus casei CRL431 modifies cytokine profiles associated to different stages of breast cancer development in mice

Breast cancer is one of the leading causes of death worldwide. It is recognised that immune system influences its promotion, progression, and metastasis, as well as their responsiveness to therapies. Previously, it was reported that milk fermented by Lactobacillus casei CRL431 decreased tumour growth and metastasis in a mouse breast cancer model, through the modulation of the host immune response. The aim of the present work was to analyse the systemic immune response induced by the administration of probiotic fermented milk (PFM) at different stages of cancer development, evaluating cytokines produced by splenocytes stimulated in vitro with 4T1 tumour cells, or its conditioned medium (CM). Groups of healthy mice and mice bearing 4T1 tumour or suffering metastasis after tumour surgery were studied. Results showed that at the early stages, PFM maintained pro-inflammatory response associated to the delay or the inhibition of tumour growth. PFM administration to mice bearing tumour maintained an important inflammatory response; however, in contrast to the milk group, this response was regulated to avoid exacerbation of inflammation. In the metastasis model, the benefits of PFM were associated to avoid the immunosuppression associated to high interleukin-10 levels. In conclusion, as cancer cells induce modifications of the immune response to favour their own growth at each stage of cancer development, PFM administration stimulated different profile of cytokines to respond to these modifications and fight against cancer cells.

Dopamine D1 receptor agonists inhibit lung metastasis of breast cancer reducing cancer stemness

The leading causes of death in breast cancer patients are disease recurrence and metastasis. Growing evidence has suggested that metastasis possibly originates from cancer stem-like cells (CSCs). Previous studies indicated dopamine decreased CSC frequency through activating dopamine D₁ receptor pathway. Hence, this study explored the efficacy of two dopamine D₁ receptor agonists in lung metastasis of breast cancer and the preliminary mechanism. The two dopamine D₁ receptor agonists, fenoldopam (FEN) and l-stepholidine (l-SPD), performed well in decreasing lung metastasis in 4T1 breast cancer model. And the cGMP in the primary tumor was significantly elevated while cAMP mildly elevated in FEN and l-SPD dosing groups. CSC markers (CD44⁺/CD24^- and ALDH⁺) and MMP2 in 4T1 primary tumor were repressed after dopamine D₁ receptor agonist administration while E-cadherin up-regulated. FEN and l-SPD also inhibited cancer stemness and cell motility in vitro, and the inhibitory effects could be reversed by dopamine D₁ receptor antagonist SCH23390. Besides, FEN impacted the white blood cell increase caused by breast cancer disease showing decreased neutrophils but increased lymphocytes. Drug safety was verified in aspects of body weight, organ index and tissue section. In conclusion, dopamine D₁ receptor agonists FEN and l-SPD showed efficacy in inhibiting metastasis along with good safety in breast cancer, thus providing an alternative for anti-metastasis therapy in the future. Furthermore, this study also indicates that dopamine D₁ receptor may be a possible target for metastatic breast cancer treatment and even other cancers at a late stage.

Pre-surgical neoadjuvant oncolytic virotherapy confers protection against rechallenge in a murine model of breast cancer

The use of oncolytic viruses (OVs) for cancer treatment is emerging as a successful strategy that combines the direct, targeted killing of the cancer with the induction of a long-lasting anti-tumor immune response. Using multiple aggressive murine models of triple-negative breast cancer, we have recently demonstrated that the early administration of oncolytic Maraba virus (MRB) prior to surgical resection of the primary tumor is sufficient to minimize the metastatic burden, protect against tumor rechallenge, cure a fraction of the mice and sensitize refractory tumors to immune checkpoint blockade without the need for further treatment. Here, we apply our surgical model to other OVs: Vesicular stomatitis virus (VSV), Adenovirus (Ad), Reovirus (Reo) and Herpes simplex virus (HSV) and show that all of the tested OVs could positively change the outcome of the treated animals. The growth of the primary and secondary tumors was differently affected by the various OVs and most of the viruses conferred survival benefits in this neoadjuvant setting despite the absence of direct treatment following rechallenge. This study establishes that OV-therapy confers long-term protection when administered in the pre-operative window of opportunity.

Investigation of antitumor effects of Lactobacillus crispatus in experimental model of breast cancer in BALB/c mice

AIM

To evaluate the effect of intraperitoneal injections of heat-killed Lactobacillus crispatus on breast tumor size and overall survival of Balb/c mouse received 4T1 mammary carcinoma. Materials and methods: Different doses of L. crispatus have been injected intraperitoneally in BALB/c mice.

RESULTS

Tumor size was decreased in the experiment group treated with 1 × 10⁸ bacteria/200 μl. Treatment with 1 × 10⁸ bacteria/200 μl resulted in survival improvement. The myeloid-derived suppressor cells and reactive oxygen species production have been increased in all groups. Cox2 expression decreased in tumor tissues of the mice treated with 10⁸ bacteria/200 μl. The expressions of Arginase and iNos increased in the spleen and tumor tissues of those treated with 5 × 10⁸ bacteria/200 μl.

CONCLUSION

We have shown the protective effect of L. crispatus on survival of tumor-bearing mice.

Thymoquinone loaded in nanostructured lipid carrier showed enhanced anticancer activity in 4T1 tumor-bearing mice

Aim: To investigate the enhancement of anticancer activity of thymoquinone (TQ) by the use of nanostructured lipid carrier (NLC) in 4T1 tumor-bearing female BALB/c mice. Material & methods: TQ was incorporated into NLC (TQNLC) by using high pressure homogenization. TQNLC and TQ were orally administered to the mice. Results & conclusion: TQNLC and TQ are potential chemotherapeutic drugs as they exhibited anticancer activity. The use of NLC as a carrier has enhanced the therapeutic property of TQ by increasing the survival rate of mice. The antimetastasis effect of TQNLC and TQ to the lungs was evidence by downregulation of MMP-2. TQNLC and TQ induced apoptosis via modulation of Bcl-2 and caspase-8 in the intrinsic apoptotic pathway.

Synergistic and low adverse effect cancer immunotherapy by immunogenic chemotherapy and locally expressed PD-L1 trap

Although great success has been obtained in the clinic, the current immune checkpoint inhibitors still face two challenging problems: low response rate and immune-related adverse effects (irAEs). Here we report the combination of immunogenic chemotherapy and locally expressed PD-L1 trap fusion protein for efficacious and safe cancer immunotherapy. We demonstrate that oxaliplatin (OxP) boosts anti-PD-L1 mAb therapy against murine colorectal cancer. By design of a PD-L1 trap and loading its coding plasmid DNA into a lipid-protamine-DNA nanoparticle, PD-L1 trap is produced transiently and locally in the tumor microenvironment, and synergizes with OxP for tumor inhibition. Significantly, unlike the combination of OxP and anti-PD-L1 mAb, the combination of OxP and PD-L1 trap does not induce obvious Th17 cells accumulation in the spleen, indicating better tolerance and lower tendency to irAEs. The reports here may highlight the potential of applying PD-L1 inhibitor, especially locally expressed PD-L1 trap, in cancer therapy following OxP-based chemotherapy.

Microsatellite-stable (MSS) colorectal cancer (CRC) has shown poor response to checkpoint blockade immunotherapy. Here, the authors show that the combination of oxaliplatin with anti-PDL1 mAb is specifically efficient in the treatment of MSS CRC.

Blocking IL-2 Signal In Vivo with an IL-2 Antagonist Reduces Tumor Growth through the Control of Regulatory T Cells

IL-2 is critical for peripheral tolerance mediated by regulatory T (Treg) cells, which represent an obstacle for effective cancer immunotherapy. Although IL-2 is important for effector (E) T cell function, it has been hypothesized that therapies blocking IL-2 signals weaken Treg cell activity, promoting immune responses. This hypothesis has been partially tested using anti-IL-2 or anti-IL-2R Abs with antitumor effects that cannot be exclusively attributed to lack of IL-2 signaling in vivo. In this work, we pursued an alternative strategy to block IL-2 signaling in vivo, taking advantage of the trimeric structure of the IL-2R. We designed an IL-2 mutant that conserves the capacity to bind to the αβ-chains of the IL-2R but not to the γ_c-chain, thus having a reduced signaling capacity. We show our IL-2 mutein inhibits IL-2 Treg cell-dependent differentiation and expansion. Moreover, treatment with IL-2 mutein reduces Treg cell numbers and impairs tumor growth in mice. A mathematical model was used to better understand the effect of the mutein on Treg and E T cells, suggesting suitable strategies to improve its design. Our results show that it is enough to transiently inhibit IL-2 signaling to bias E and Treg cell balance in vivo toward immunity.

Smac mimetics and oncolytic viruses synergize in driving anticancer T-cell responses through complementary mechanisms

Second mitochondrial activator of caspase (Smac)-mimetic compounds and oncolytic viruses were developed to kill cancer cells directly. However, Smac-mimetic compound and oncolytic virus therapies also modulate host immune responses in ways we hypothesized would complement one another in promoting anticancer T-cell immunity. We show that Smac-mimetic compound and oncolytic virus therapies synergize in driving CD8+ T-cell responses toward tumors through distinct activities. Smac-mimetic compound treatment with LCL161 reinvigorates exhausted CD8+ T cells within immunosuppressed tumors by targeting tumor-associated macrophages for M1-like polarization. Oncolytic virus treatment with vesicular stomatitis virus (VSVΔM51) promotes CD8+ T-cell accumulation within tumors and CD8+ T-cell activation within the tumor-draining lymph node. When combined, LCL161 and VSVΔM51 therapy engenders CD8+ T-cell-mediated tumor control in several aggressive mouse models of cancer. Smac-mimetic compound and oncolytic virus therapies are both in clinical development and their combination therapy represents a promising approach for promoting anticancer T-cell immunity.Oncolytic viruses (OV) and second mitochondrial activator of caspase (Smac)-mimetic compounds (SMC) synergistically kill cancer cells directly. Here, the authors show that SMC and OV therapies combination also synergize in vivo by promoting anticancer immunity through an increase in CD8+ T-cell response.

In vitro Cytotoxicity Effects of 197Au/PAMAMG4 and 198Au/PAMAMG4 Nanocomposites Against MCF7 and 4T1 Breast Cancer Cell Lines

Purpose: Study on gold based therapeutic agents for cancer cells deracination has become under scrutiny in recent years owing to effective treatments are not available for rapidly progressive cancers. The aim of present study was to examine efficiency of radioactive 198Au/PAMAMG4 and non-radioactive 197Au/PAMAMG4 nancomposites against 4T1 and MCF7 breast cancer cell lines. Methods: The PAMAMG4 dendrimer was treated with the gold anions and then, the mixture was chemically reduced by NaBH4. Prepared 197Au/PAMAMG4 was bombarded by thermal neutrons in the Tehran Research Reactor to 198Au/PAMAMG4 be produced. Prepared nanocomposites were characterized by means of FT-IR, 1H NMR, Zeta-potential measurements, TEM and EDX analyses. The radionuclidic purity of the 198Au/PAMAMG4 solution was determined using purity germanium (HPGe) spectroscopy and its stability in the presence of human serum was studied. In vitro studies were carried out to compare toxicity of PAMAMG4, 197Au/PAMAMG4 and 198Au/PAMAMG4 towards 4T1 and MCF7 cancerous cells and C2C12 normal cell lines. Results: Characterization results exhibited that invitro agents, 197Au/PAMAMG4 and 198Au/PAMAMG4, were synthesized successfully. Cells viability after 24 h, 48 h, and 72 h incubation, using MTT assay showed that the toxicity of 198Au/PAMAMG4 is significantly superior in comparison with 197Au/PAMAMG4 and PAMAMG4. Furthermore, the toxicity of 198Au/PAMAMG4 was higher on cancerous cells especially in higher level of concentrations after 72 hours (P<0.05). Conclusion: In the current study, the preparation of 197Au/PAMAMG4 and 198Au/PAMAMG4 is described and the cytotoxic properties of them against the MCF7, 4T1 cancerous cells and C2C12 normal cells were evaluated using MTT assay.

Therapy targeted to the metastatic niche is effective in a model of stage IV breast cancer

Treatment of stage IV metastatic breast cancer patients is limited to palliative options and represents an unmet clinical need. Here, we demonstrate that pharmacological inhibition of miRNA-10b - a master regulator of metastatic cell viability – leads to elimination of distant metastases in a mouse model of metastatic breast cancer. This was achieved using the miRNA-10b inhibitory nanodrug, MN-anti-miR10b, which consists of magnetic nanoparticles, conjugated to LNA-based miR-10b antagomirs. Intravenous injection of MN-anti-miR10b into mice bearing lung, bone, and brain metastases from breast cancer resulted in selective accumulation of the nanodrug in metastatic tumor cells. Weekly treatments of mice with MN-anti-miR-10b and low-dose doxorubicin resulted in complete regression of pre-existing distant metastases in 65% of the animals and a significant reduction in cancer mortality. These observations were supported by dramatic reduction in proliferation and increase in apoptosis in metastatic sites. On a molecular level, we observed a significant increase in the expression of HOXD10, which is a known target of miRNA-10b. These results represent first steps into the uncharted territory of therapy targeted to the metastatic niche.

Bone marrow produces sufficient alloreactive natural killer (NK) cells in vivo to cure mice from subcutaneously and intravascularly injected 4T1 breast cancer

Purpose

Administration of 5 million alloreactive natural killer (NK) cells after low-dose chemo-irradiation cured mice of 4T1 breast cancer, supposedly dose dependent. We now explored the efficacy of bone marrow as alternative in vivo source of NK cells for anti-breast cancer treatment, as methods for in vitro clinical scale NK cell expansion are still in developmental phases.

Methods

Progression-free survival (PFS) after treatment with different doses of spleen-derived alloreactive NK cells to 4T1-bearing Balb/c mice was measured to determine a dose–response relation. The potential of bone marrow as source of alloreactive NK cells was explored using MHC-mismatched mice as recipients of 4T1. Chemo-irradiation consisted of 2× 2 Gy total body irradiation and 200 mg/kg cyclophosphamide. Antibody-mediated in vivo NK cell depletion was applied to demonstrate the NK cell’s role.

Results

Administration of 2.5 instead of 5 million alloreactive NK cells significantly reduced PFS, evidencing dose responsiveness. Compared to MHC-matched receivers of subcutaneous 4T1, fewer MHC-mismatched mice developed tumors, which was due to NK cell alloreactivity because in vivo NK cell depletion facilitated tumor growth. Application of low-dose chemo-irradiation increased plasma levels of NK cell-activating cytokines, NK cell activity and enhanced NK cell-dependent elimination of subcutaneous tumors. Intravenously injected 4T1 was eliminated by alloreactive NK cells in MHC-mismatched recipients without the need for chemo-irradiation.

Conclusions

Bone marrow is a suitable source of sufficient alloreactive NK cells for the cure of 4T1 breast cancer. These results prompt clinical exploration of bone marrow transplantation from NK-alloreactive MHC-mismatched donors in patients with metastasized breast cancer.

Elimination of epithelial-like and mesenchymal-like breast cancer stem cells to inhibit metastasis following nanoparticle-mediated photothermal therapy

Increasing evidence suggesting breast cancer stem cells (BCSCs) drive metastasis and evade traditional therapies underscores a critical need to exploit the untapped potential of nanotechnology to develop innovative therapies that will significantly improve patient survival. Photothermal therapy (PTT) to induce localized hyperthermia is one of few nanoparticle-based treatments to enter clinical trials in human cancer patients, and has recently gained attention for its ability to induce a systemic immune response targeting distal cancer cells in mouse models. Here, we first conduct classic cancer stem cell (CSC) assays, both in vitro and in immune-compromised mice, to demonstrate that PTT mediated by highly crystallized iron oxide nanoparticles effectively eliminates BCSCs in translational models of triple negative breast cancer. PTT in vitro preferentially targets epithelial-like ALDH + BCSCs, followed by mesenchymal-like CD44+/CD24- BCSCs, compared to bulk cancer cells. PTT inhibits BCSC self-renewal through reduction of mammosphere formation in primary and secondary generations. Secondary implantation in NOD/SCID mice reveals the ability of PTT to impede BCSC-driven tumor formation. Next, we explore the translational potential of PTT using metastatic and immune-competent mouse models. PTT to inhibit BCSCs significantly reduces metastasis to the lung and lymph nodes. In immune-competent BALB/c mice, PTT effectively eliminates ALDH + BCSCs. These results suggest the feasibility of incorporating PTT into standard clinical treatments such as surgery to enhance BCSC destruction and inhibit metastasis, and the potential of such combination therapy to improve long-term survival in patients with metastatic breast cancer.

CD4+ and CD8+ T cells have opposing roles in breast cancer progression and outcome

The Cancer Immunoediting concept has provided critical insights suggesting dual functions of immune system during the cancer initiation and development. However, the dynamics and roles of CD4⁺ and CD8⁺ T cells in the pathogenesis of breast cancer remain unclear. Here we utilized two murine breast cancer models (4T1 and E0771) and demonstrated that both CD4⁺ and CD8⁺ T cells were increased and involved in immune responses, but with distinct dynamic trends in breast cancer development. In addition to cell number increases, CD4⁺ T cells changed their dominant subsets from Th1 in the early stages to Treg and Th17 cells in the late stages of the cancer progression. We also analyzed CD4⁺ and CD8⁺ T cell infiltration in primary breast cancer tissues from cancer patients. We observed that CD8⁺ T cells are the key effector cell population mediating effective anti-tumor immunity resulting in better clinical outcomes. In contrast, intra-tumoral CD4⁺ T cells have negative prognostic effects on breast cancer patient outcomes. These studies indicate that CD4⁺ and CD8⁺ T cells have opposing roles in breast cancer progression and outcomes, which provides new insights relevant for the development of effective cancer immunotherapeutic approaches.

Tetraspanin CD81 promotes tumor growth and metastasis by modulating the functions of T regulatory and myeloid-derived suppressor cells

Tumor cells counteract innate and adaptive antitumor immune responses by recruiting regulatory T cells (Treg) and innate myeloid-derived suppressor cells (MDSC), which facilitate immune escape and metastatic dissemination. Here we report a role in these recruitment processes for CD81, a member of the tetraspanin family of proteins that have been implicated previously in cancer progression. We found that genetic deficiency in CD81 reduced tumor growth and metastasis in two genetic mouse backgrounds and multiple tumor models. Mechanistic investigations revealed that CD81 was not required for normal development of Treg and MDSC but was essential for immunosuppressive functions. Notably, adoptive transfer of wild-type Treg into CD81-deficient mice was sufficient to promote tumor growth and metastasis. Our findings suggested that CD81 modulates adaptive and innate immune responses, warranting further investigation of CD81 in immunomodulation in cancer and its progression.

Nanostructured lipid carrier improved in vivo anti-tumor and immunomodulatory effect of Zerumbone in 4T1 challenged mice

Nanostructured lipid carrier (NLC) encapsulation enhanced thein vivoantitumor, antitumor immunity and anti-inflammatory effects of Zerumbone on 4T1 challenged mice.

Adoptive T-Cell Immunotherapy

Epstein-Barr virus (EBV) is associated with a range of malignancies involving B cells, T cells, natural killer (NK) cells, epithelial cells, and smooth muscle. All of these are associated with the latent life cycles of EBV, but the pattern of latency-associated viral antigens expressed in tumor cells depends on the type of tumor. EBV-specific T cells (EBVSTs) have been explored as prophylaxis and therapy for EBV-associated malignancies for more than two decades. EBVSTs have been most successful as prophylaxis and therapy for post-transplant lymphoproliferative disease (PTLD) , which expresses the full array of latent EBV antigens (type 3 latency), in hematopoietic stem-cell transplant (HSCT) recipients. While less effective, clinical studies have also demonstrated their therapeutic potential for PTLD post-solid organ transplant and for EBV-associated malignancies such as Hodgkin's lymphoma, non-Hodgkin's lymphoma, and nasopharyngeal carcinoma (NPC) that express a limited array of latent EBV antigens (type 2 latency). Several approaches are actively being pursued to improve the antitumor activity of EBVSTs including activation and expansion of T cells specific for the EBV antigens expressed in type 2 latency, genetic approaches to render EBVSTs resistant to the immunosuppressive tumor environment, and combination approaches with other immune-modulating modalities. Given the recent advances and renewed interest in cell therapy, we hope that EBVSTs will become an integral part of our treatment armamentarium against EBV-positive malignancies in the near-future.

Co‐existence of Echinococcus granulosus infection and cancer metastasis in the liver correlates with reduced Th1 immune responses

A possible relationship between cancer and Echinococcus granulosus infection has been postulated. As T cells are critical players in immune responses against both infections and malignancies, in an experimental model of secondary echinococcosis and breast cancer, this study aims to observe the progression of cancer and to determine the characters of T‐cell responses. 4T1 breast tumour cells were subcutaneously injected into mammary region, whereas protoscoleces were intraperitoneally inoculated into the mice. Hydatid cysts, tumours and metastases were determined with macroscopic and histopathological evaluation. T cells found in spleen, liver and tumour were characterised by flow cytometric analysis of CD3, CD4, CD8, CD25, CCR5, CCR3, IL‐4 and IFN‐γ. In the mice inoculated both with protoscoleces and with breast tumour cells, increased frequency of cancer metastasis was observed in the liver. The amount of CD4+ T cells was increased in the liver and in the spleen of mice infected with E. granulosus. However, co‐existence of echinococcosis and metastatic lesions in the liver was associated with significant reduction in the IFN‐γ+ and CCR5+ Th1 cells and increase in the CD25+ T cells. Our results may indicate an immunological link between cystic echinococcosis and cancer that allows tumour metastasis to flourish in the liver.

Chemopreventive and therapeutic potential of "naringenin," a flavanone present in citrus fruits

Cancer is one of the major causes of deaths in developed countries and is emerging as a major public health burden in developing countries too. Changes in cancer prevalence patterns have been noticed due to rapid urbanization and changing lifestyles. One of the major concerns is an influence of dietary habits on cancer rates. Approaches to prevent cancer are many and chemoprevention or dietary cancer prevention is one of them. Therefore, nutritional practices are looked at as effective types of dietary cancer prevention strategies. Attention has been given to identifying plant-derived dietary agents, which could be developed as a promising chemotherapeutic with minimal toxic side effects. Naringenin, a phytochemical mainly present in citrus fruits and tomatoes, is a frequent component of the human diet and has gained increasing interest because of its positive health effects not only in cancer prevention but also in noncancer diseases. In the last few years, significant progress has been made in studying the biological effects of naringenin at cellular and molecular levels. This review examines the cancer chemopreventive/therapeutic effects of naringenin in an organ-specific format, evaluating its limitations, and its considerable potential for development as a cancer chemopreventive/therapeutic agent.

IFN-γ mediates graft-versus-breast cancer effects via enhancing cytotoxic T lymphocyte activity

Previous studies have demonstrated the beneficial effect of graft-versus-tumor (GVT) following hematopoietic stem cell transplantation (HSCT) on the incidence of leukemia relapse and the overall survival rate of patients with leukemia; however, detailed mechanisms underlying the effects GVT exhibits on solid tumors following allogeneic HSCT are yet to be elucidated. The aim of the present study was to investigate the immune mechanism underlying the effect of interferon (IFN)-γ on GVT following allogeneic HSCT in breast cancer therapy. An in situ breast cancer mouse model was established by injecting 5×10⁴ 4T1 cells into the mammary fat pads of BALB/c mice. The 4T1 cells were transfected with the firefly luciferase reporter gene in order to monitor the tumor progression in real time. An allogeneic HSCT model was then established by transplanting bone marrow mononuclear cells from C57BL/6 mice to the BALB/c mice. To investigate the influence of T lymphocyte proliferation following allogeneic bone marrow transplantation, the levels of CD3⁺CD8⁺ cytotoxic T lymphocytes (CTLs) and CD4⁺CD25⁺ regulatory T cells were determined. In addition, IFN-γ and granzyme B expression levels in splenic lymphocytes were analyzed using flow cytometry. Allogeneic HSCT was found to significantly promote the proliferation and cytotoxicity of CTLs and suppress the growth of breast cancer. Furthermore, the secretory levels of IFN-γ and granzyme B by T cells were elevated following allogeneic HSCT. These results indicated that alloreactive T cells increased the secretion of IFN-γ, which promoted the alloresponse of donor CTLs. In addition, the CTLs produced granzyme B, which exerted a tumor suppressive effect.

Oral tolerance to cancer can be abrogated by T regulatory cell inhibition

Oral administration of tumour cells induces an immune hypo-responsiveness known as oral tolerance. We have previously shown that oral tolerance to a cancer is tumour antigen specific, non-cross-reactive and confers a tumour growth advantage. We investigated the utilisation of regulatory T cell (Treg) depletion on oral tolerance to a cancer and its ability to control tumour growth. Balb/C mice were gavage fed homogenised tumour tissue--JBS fibrosarcoma (to induce oral tolerance to a cancer), or PBS as control. Growth of subcutaneous JBS tumours were measured; splenic tissue excised and flow cytometry used to quantify and compare systemic Tregs and T effector (Teff) cell populations. Prior to and/or following tumour feeding, mice were intraperitoneally administered anti-CD25, to inactivate systemic Tregs, or given isotype antibody as a control. Mice which were orally tolerised prior to subcutaneous tumour induction, displayed significantly higher systemic Treg levels (14% vs 6%) and faster tumour growth rates than controls (p<0.05). Complete regression of tumours were only seen after Treg inactivation and occurred in all groups--this was not inhibited by tumour feeding. The cure rates for Treg inactivation were 60% during tolerisation, 75% during tumour growth and 100% during inactivation for both tolerisation and tumour growth. Depletion of Tregs gave rise to an increased number of Teff cells. Treg depletion post-tolerisation and post-tumour induction led to the complete regression of all tumours on tumour bearing mice. Oral administration of tumour tissue, confers a tumour growth advantage and is accompanied by an increase in systemic Treg levels. The administration of anti-CD25 Ab decreased Treg numbers and caused an increase in Teffs. Most notably Treg cell inhibition overcame established oral tolerance with consequent tumor regression, especially relevant to foregut cancers where oral tolerance is likely to be induced by the shedding of tumour tissue into the gut.

Dendritic cells: In vitro culture in two- and three-dimensional collagen systems and expression of collagen receptors in tumors and atherosclerotic microenvironments

Dendritic cells (DCs) are immune cells found in the peripheral tissues where they sample the organism for infections or malignancies. There they take up antigens and migrate towards immunological organs to contact and activate T lymphocytes that specifically recognize the antigen presented by these antigen presenting cells. In the steady state there are several types of resident DCs present in various different organs. For example, in the mouse, splenic DC populations characterized by the co-expression of CD11c and CD8 surface markers are specialized in cross-presentation to CD8 T cells, while CD11c/SIRP-1α DCs seem to be dedicated to activating CD4 T cells. On the other hand, DCs have also been associated with the development of various diseases such as cancer, atherosclerosis, or inflammatory conditions. In such disease, DCs can participate by inducing angiogenesis or immunosuppression (tumors), promoting autoimmune responses, or exacerbating inflammation (atherosclerosis). This change in DC biology can be prompted by signals in the microenvironment. We have previously shown that the interaction of DCs with various extracellular matrix components modifies the immune properties and angiogenic potential of these cells. Building on those studies, herewith we analyzed the angiogenic profile of murine myeloid DCs upon interaction with 2D and 3D type-I collagen environments. As determined by PCR array technology and quantitative PCR analysis we observed that interaction with these collagen environments induced the expression of particular angiogenic molecules. In addition, DCs cultured on collagen environments specifically upregulated the expression of CXCL-1 and -2 chemokines. We were also able to establish DC cultures on type-IV collagen environments, a collagen type expressed in pathological conditions such as atherosclerosis. When we examined DC populations in atherosclerotic veins of Apolipoprotein E deficient mice we observed that they expressed adhesion molecules capable of interacting with collagen. Finally, to further investigate the interaction of DCs with collagen in other pathological conditions, we determined that both murine ovarian and breast cancer cells express several collagen molecules that can contribute to shape their particular tumor microenvironment. Consistently, tumor-associated DCs were shown to express adhesion molecules capable of interacting with collagen molecules as determined by flow cytometry analysis. Of particular relevance, tumor-associated DCs expressed high levels of CD305/LAIR-1, an immunosuppressive receptor. This suggests that signaling through this molecule upon interaction with collagen produced by tumor cells might help define the poorly immunogenic status of these cells in the tumor microenvironment. Overall, these studies demonstrate that through interaction with collagen proteins, DCs can be capable of modifying the microenvironments of inflammatory disease such as cancer or atherosclerosis.

Retracted Article: Radio frequency triggered curcumin delivery from thermo and pH responsive nanoparticles containing gold nanoparticles and its in vivo localization studies in an orthotopic breast tumor model

RF responsive gold nanoparticles containing curcumin encapsulated chitosan-graft-poly(N-vinyl caprolactam) induced apoptosis on 4T1 breast cancer cells on RF exposure.

Stable tumor vessel normalization with pO₂ increase and endothelial PTEN activation by inositol trispyrophosphate brings novel tumor treatment

Tumor hypoxia is a characteristic of cancer cell growth and invasion, promoting angiogenesis, which facilitates metastasis. Oxygen delivery remains impaired because tumor vessels are anarchic and leaky, contributing to tumor cell dissemination. Counteracting hypoxia by normalizing tumor vessels in order to improve drug and radio therapy efficacy and avoid cancer stem-like cell selection is a highly challenging issue. We show here that inositol trispyrophosphate (ITPP) treatment stably increases oxygen tension and blood flow in melanoma and breast cancer syngeneic models. It suppresses hypoxia-inducible factors (HIFs) and proangiogenic/glycolysis genes and proteins cascade. It selectively activates the tumor suppressor phosphatase and tensin homolog (PTEN) in vitro and in vivo at the endothelial cell (EC) level thus inhibiting PI3K and reducing tumor AKT phosphorylation. These mechanisms normalize tumor vessels by EC reorganization, maturation, pericytes attraction, and lowering progenitor cells recruitment in the tumor. It strongly reduces vascular leakage, tumor growth, drug resistance, and metastasis. ITPP treatment avoids cancer stem-like cell selection, multidrug resistance (MDR) activation and efficiently enhances chemotherapeutic drugs activity. These data show that counteracting tumor hypoxia by stably restoring healthy vasculature is achieved by ITPP treatment, which opens new therapeutic options overcoming hypoxia-related limitations of antiangiogenesis-restricted therapies. By achieving long-term vessels normalization, ITPP should provide the adjuvant treatment required in order to overcome the subtle definition of therapeutic windows for in vivo treatments aimed by the current strategies against angiogenesis-dependent tumors.

Naringenin reduces lung metastasis in a breast cancer resection model

Metastasis is the main cause of death in cancer patients. To improve the outcomes of patients undergoing a surgery, new adjuvant therapies that can effectively inhibit metastases have to be developed. Studies have shown that flavonoid naringenin, a natural product that is mainly present in grapes and citrus, may contribute to cancer prevention. It has many advantages compared to traditional chemotherapeutic drugs, such as low toxicity. To determine whether naringenin can also inhibit metastases, a breast cancer resection model that mimics clinical situations was established. We found that orally administered naringenin significantly decreased the number of metastatic tumor cells in the lung and extended the life span of tumor resected mice. Flow cytometry analysis revealed that T cells displayed enhanced antitumor activity in naringenin treated mice, with an increased proportion of IFN-γ and IL-2 expressing T cells. In vitro studies further demonstrated that relief of immunosuppression caused by regulatory T cells might be the fundamental mechanism of metastasis inhibition by naringenin. These results indicate that orally administered naringenin can inhibit the outgrowth of metastases after surgery via regulating host immunity. Thus, naringenin can be an ideal surgical adjuvant therapy for breast cancer patients.

Cancer-testis antigen, BORIS based vaccine delivered by dendritic cells is extremely effective against a very aggressive and highly metastatic mouse mammary carcinoma

Here, we analyze for the first time the immunological and therapeutic efficacy of a dendritic cell (DC) vaccine based on a cancer-testis antigen, Brother of regulator of imprinted sites (BORIS), an epigenetically acting tumor-promoting transcription factor. Vaccination of mice with DC loaded with truncated form of BORIS (DC/mBORIS) after 4T1 mammary tumor implantation induced strong anti-cancer immunity, inhibited tumor growth (18.75% of mice remained tumor-free), and dramatically lowered the number of spontaneous clonogenic metastases (50% of mice remained metastases-free). Higher numbers of immune effector CD4 and CD8 T cells infiltrated the tumors of vaccinated mice vs. control animals. Vaccination significantly decreased the number of myeloid-derived suppressor cells (MDSCs) infiltrating the tumor sites, but not MDSCs in the spleens of vaccinated animals. These data suggest that DC-based mBORIS vaccination strategies have significant anti-tumor activity in a therapeutic setting and will be more effective when combined with agents to attenuate tumor-associated immune suppression.

Integrating costimulatory agonists to optimize immune-based cancer therapies

While immunotherapy for cancer has become increasingly popular, clinical benefits for such approaches remain limited. This is likely due to tumor-associated immune suppression, particularly in the advanced-disease setting. Thus, a major goal of novel immunotherapeutic design has become the coordinate reversal of existing immune dysfunction and promotion of specific tumoricidal T-cell function. Costimulatory members of the TNF-receptor family are important regulators of T-cell-mediated immunity. Notably, agonist ligation of these receptors restores potent antitumor immunity in the tumor-bearing host. Current Phase I/II evaluation of TNF-receptor agonists as single-modality therapies will illuminate their safety, mechanism(s) of action, and best use in prospective combinational immunotherapy approaches capable of yielding superior benefits to cancer patients.

Susceptibility of breast cancer cells to an oncolytic matrix (M) protein mutant of vesicular stomatitis virus

Matrix (M) protein mutants of vesicular stomatitis virus (VSV), such as rM51R-M virus, are attractive candidates as oncolytic viruses for tumor therapies because of their capacity to selectively target cancer cells. The effectiveness of rM51R-M virus as an antitumor agent for the treatment of breast cancer was assessed by determining the ability of rM51R-M virus to infect and kill breast cancer cells in vitro and in vivo. Several human- and mouse-derived breast cancer cell lines were susceptible to infection and killing by rM51R-M virus. Importantly, non-tumorigenic cell lines from normal mammary tissues were also sensitive to VSV infection suggesting that oncogenic transformation does not alter the susceptibility of breast cancer cells to oncolytic VSV. In contrast to results obtained in vitro, rM51R-M virus was only partially effective at inducing regression of primary breast tumors in vivo. Furthermore, we were unable to induce complete regression of the primary and metastatic tumors when tumor-bearing mice were treated with a vector expressing interleukin (IL)-12 or a combination of rM51R-M virus and IL-12. Our results indicate that although breast cancer cells may be susceptible to VSV in vitro, more aggressive treatment combinations are required to effectively treat both local and metastatic breast cancers in vivo.