Leukocytes in mammary development and cancer

The Immune Microenvironment of Breast Cancer Progression

Inflammation is now recognized as a hallmark of cancer. Genetic changes in the cancer cell are accepted as the match that lights the fire, whilst inflammation is seen as the fuel that feeds the fire. Once inside the tumour, the immune cells secrete cytokines that kick-start angiogenesis to ferry in much-needed oxygen and nutrients that encourage the growth of tumours. There is now irrefutable data demonstrating that the immune contexture of breast tumours can influence growth and metastasis. A higher immune cell count in invasive breast cancer predicts prognosis and response to chemotherapy. We are beginning now to define the specific innate and adaptive immune cells present in breast cancer and their role not just in the progression of invasive disease, but also in the development of pre-invasive lesions and their transition to malignant tumours. This review article focusses on the immune cells present in early stage breast cancer and their relationship with the immunoediting process involved in tumour advancement.

The role of collagen in cancer: from bench to bedside

Collagen is the major component of the tumor microenvironment and participates in cancer fibrosis. Collagen biosynthesis can be regulated by cancer cells through mutated genes, transcription factors, signaling pathways and receptors; furthermore, collagen can influence tumor cell behavior through integrins, discoidin domain receptors, tyrosine kinase receptors, and some signaling pathways. Exosomes and microRNAs are closely associated with collagen in cancer. Hypoxia, which is common in collagen-rich conditions, intensifies cancer progression, and other substances in the extracellular matrix, such as fibronectin, hyaluronic acid, laminin, and matrix metalloproteinases, interact with collagen to influence cancer cell activity. Macrophages, lymphocytes, and fibroblasts play a role with collagen in cancer immunity and progression. Microscopic changes in collagen content within cancer cells and matrix cells and in other molecules ultimately contribute to the mutual feedback loop that influences prognosis, recurrence, and resistance in cancer. Nanoparticles, nanoplatforms, and nanoenzymes exhibit the expected gratifying properties. The pathophysiological functions of collagen in diverse cancers illustrate the dual roles of collagen and provide promising therapeutic options that can be readily translated from bench to bedside. The emerging understanding of the structural properties and functions of collagen in cancer will guide the development of new strategies for anticancer therapy.

Small molecule immunomodulation: the tumor microenvironment and overcoming immune escape

Immunotherapy has led to a paradigm shift in the treatment of many advanced malignancies. Despite the success in treatment of tumors like non-small cell lung cancer (NSCLC) and melanoma, checkpoint inhibition-based immunotherapy has limitations. Many tumors, such as pancreatic cancer, are less responsive to checkpoint inhibitors, where patients tend to have a limited duration of benefit and where clinical responses are more robust in patients who are positive for predictive biomarkers. One of the critical factors that influence the efficacy of immunotherapy is the tumor microenvironment (TME), which contains a heterogeneous composition of immunosuppressive cells. Myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs) alter the immune landscape of the TME and serve as facilitators of tumor proliferation, metastatic growth and immunotherapy resistance. Small molecule inhibitors that target these components of the TME have been developed. This special issue review focuses on two promising classes of immunomodulatory small molecule inhibitors: colony stimulating factor-1 receptor (CSF-1R) and focal adhesion kinase (FAK). Small molecule inhibitors of CSF-1R reprogram the TME and TAMs, and lead to enhanced T-cell-mediated tumor eradication. FAK small molecule inhibitors decrease the infiltration MDSCs, TAMs and regulatory T-cells. Additionally, FAK inhibitors are implicated as modulators of stromal density and cancer stem cells, leading to a TME more conducive to an anti-tumor immune response. Immunomodulatory small molecule inhibitors present a unique opportunity to attenuate immune escape of tumors and potentiate the effectiveness of immunotherapy and traditional cytotoxic therapy.

Regulation of Immunity in Breast Cancer

Breast cancer affects millions of women worldwide, leading to many deaths and significant economic burden. Although there are numerous treatment options available, the huge potentials of immunotherapy in the management of localized and metastatic breast cancer is currently being explored. However, there are significant gaps in understanding the complex interactions between the immune system and breast cancer. The immune system can be pro-tumorigenic and anti-tumorigenic depending on the cells involved and the conditions of the tumor microenvironment. In this review, we discuss current knowledge of breast cancer, including treatment options. We also give a brief overview of the immune system and comprehensively highlight the roles of different cells of the immune system in breast tumorigenesis, including recent research discoveries. Lastly, we discuss some immunotherapeutic strategies for the management of breast cancer.

Identification of monocyte-like precursors of granulocytes in cancer as a mechanism for accumulation of PMN-MDSCs

Mastio et al. describe monocytic precursors of granulocytes. These precursors are barely detectable in steady state conditions and are not consequential for differentiation of granulocytes. However, they accumulate in cancer and substantially contribute to PMN-MDSC expansion.

We have identified a precursor that differentiates into granulocytes in vitro and in vivo yet belongs to the monocytic lineage. We have termed these cells monocyte-like precursors of granulocytes (MLPGs). Under steady state conditions, MLPGs were absent in the spleen and barely detectable in the bone marrow (BM). In contrast, these cells significantly expanded in tumor-bearing mice and differentiated to polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs). Selective depletion of monocytic cells had no effect on the number of granulocytes in naive mice but decreased the population of PMN-MDSCs in tumor-bearing mice by 50%. The expansion of MLPGs was found to be controlled by the down-regulation of Rb1, but not IRF8, which is known to regulate the expansion of PMN-MDSCs from classic granulocyte precursors. In cancer patients, putative MLPGs were found within the population of CXCR1⁺CD15⁻CD14⁺HLA-DR^−/lo monocytic cells. These findings describe a mechanism of abnormal myelopoiesis in cancer and suggest potential new approaches for selective targeting of MDSCs.

From immune checkpoints to vaccines: The past, present and future of cancer immunotherapy

Cancer is a worldwide medical problem with significant repercussions on individual patients and societies as a whole. In order to alter the outcomes of this deadly disease the treatment of cancer over the centuries has undergone a unique evolution. However, utilizing the best treatment modalities and achieving cures or long-term durable responses have been inconsistent and limited, that is until recently. Contemporary research has highlighted a fundamental gap in our understanding of how we approach treating cancer, by revealing the intricate relationship between the immune system and tumors. In this atmosphere, the growth of immunotherapy has not only forever changed our understanding of cancer biology, but the manner by which we treat patients. It's paradigm shifting success has led to the approval of over 10 different immunotherapeutic agents, including checkpoint inhibitors, vaccine-based therapies, oncolytic viruses and T cell directed therapies for nearly 20 different indications across countless tumor types. Despite the breakthroughs that have occurred in the field of immunotherapy, it has not been the panacea for all cancers. With a deeper understanding of the immune system we have been able to peer into tumor immune escape and therapy resistance. Simultaneously this understanding has paved the way for the investigation and development of novel immune system altering agents and combinatorial therapies. In this chapter we review the immune system and its intricate relationship with cancer, the evolution of immunotherapy, its current landscape, and future directions in the context of resistance mechanisms and the challenges faced by immunotherapy against cancer.

Interleukin-1β provided by KIT-competent mast cells is required for KRAS-mutant lung adenocarcinoma

Mast cells (MC) have been identified in human lung adenocarcinoma (LADC) tissues, but their functional role has not been investigated in vivo. For this, we applied three mouse models of KRAS-mutant LADC to two different MC-deficient mouse strains (cKit^Wsh and Cpa3.Cre). Moreover, we derived MC gene signatures from murine bone marrow-derived MC and used them to interrogate five human cohorts of LADC patients. Tumor-free cKit^Wsh and Cpa3.Cre mice were deficient in alveolar and skin KIT-dependent (KIT+) MC, but cKit^Wsh mice retained normal KIT-independent (KIT-) MC in the airways. Both KIT+ and KIT- MC infiltrated murine LADC to varying degrees, but KIT+ MC were more abundant and promoted LADC initiation and progression through interleukin-1β secretion. KIT+ MC and their transcriptional signature were significantly enriched in human LADC compared to adjacent normal tissue, especially in the subset of patients with KRAS mutations. Importantly, MC density increased with tumor stage and high overall expression of the KIT+ MC signature portended poor survival. Collectively, our results indicate that KIT+ MC foster LADC development and represent marked therapeutic targets.

Fetal-derived macrophages dominate in adult mammary glands

Macrophages serve multiple functions including immune regulation, morphogenesis, tissue homeostasis and healing reactions. The current paradigm holds that mammary gland macrophages first arise postnatally during the prepubertal period from the bone marrow-derived monocytes. Here we delineate the origins of tissue-resident mammary gland macrophages using high-dimension phenotypic analyses, cell-fate mapping experiments, gene-deficient mice lacking selective macrophage subtypes, and antibody-based depletion strategies. We show that tissue-resident macrophages are found in mammary glands already before birth, and that the yolk sac-derived and fetal liver-derived macrophages outnumber the adult-derived macrophages in the mammary gland also in the adulthood. In addition, fetal-derived mammary gland macrophages have a characteristic phenotype, display preferential periductal and perivascular localization, and are highly active in scavenging. These findings identify fetal-derived macrophages as the predominant leukocyte type in the adult mammary gland stroma, and reveal previously unknown complexity of macrophage biology in the breast.

Tissue-resident macrophages are highly specialized phagocytes that serve multiple functions. Here, using high-dimension analyses and fate-mapping experiments, the authors show that fetal liver-derived macrophages dominate the mammary gland in neonatal and adult, and display characteristic phenotypes and functions.

CD68, CD163, and matrix metalloproteinase 9 (MMP-9) co-localization in breast tumor microenvironment predicts survival differently in ER-positive and -negative cancers

Background

The role of tumor-associated macrophages (TAMs) in the cancer immune landscape and their potential as treatment targets or modulators of response to treatment are gaining increasing interest. TAMs display high molecular and functional complexity. Therefore their objective assessment as breast cancer biomarkers is critical. The aims of this study were to objectively determine the in situ expression and significance of TAM biomarkers (CD68, CD163, and MMP-9) in breast cancer and to identify subclasses of patients who could benefit from TAM-targeting therapies.

Methods

We measured CD68, CD163, and MMP-9 protein expression in formalin-fixed paraffin-embedded tissues of breast carcinomas represented in tissue microarray format using multiplexed quantitative immunofluorescence (QIF) in two independent Yale cohorts: cohort A—n = 398, estrogen receptor–positive (ER⁺) and ER⁻ cases—and the triple-negative breast cancer (TNBC)-only cohort B (n = 160). Associations between macrophage markers, ER status, and survival were assessed. Protein expression measured by QIF was compared with mRNA expression data from the METABRIC study.

Results

All three macrophage markers were co-expressed, displaying higher expression in ER⁻ cancers. High pan-macrophage marker CD68 correlated with poorer overall survival (OS) only in ER⁻ cases of cohort A (P = 0.02). High expression of CD163 protein in TAMs was associated with improved OS in ER⁻ cases (cohort A, P = 0.03 and TNBC cohort B, P = 0.04, respectively) but not in ER⁺ cancers. MMP-9 protein was not individually associated with OS. High expression of MMP-9 in the CD68⁺/CD163⁺ TAMs was associated with worse OS in ER⁺ tumors (P <0.001) but not in ER⁻ cancers. In the METABRIC dataset, mRNA levels followed the co-expression pattern observed in QIF but did not always show the same trend regarding OS.

Conclusions

Macrophage activity markers correlate with survival differently in ER⁺ and ER⁻ cancers. The association between high co-expression and co-localization of MMP-9/CD163/CD68 and poor survival in ER⁺ cancers suggests that these cancers may be candidates for macrophage-targeted therapies.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-1076-x) contains supplementary material, which is available to authorized users.

Fusobacterium and Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer worldwide and its pathogenesis has been extensively explored over the past decades. Recently, microorganisms in the gastrointestinal tract have emerged as potential etiological agents. In particular, a direct proportional association between Fusobacterium and CRC has been described. Since then, the functional impact of Fusobacterium in CRC development has been studied using various mouse models. Although some epidemiologic studies did not establish an obvious relationship between Fusobacterium and CRC, numerous pathogenic mechanisms leading to the disease have been described. For instance, Fusobacterium can activate the E-cadherin/β-catenin signaling pathway and is associated with particular epigenetic phenotype, such as microsatellite instability (MSI) and hypermethylation, via its strong adhesive and invasive abilities resulting in malignant transformation of epithelial cells. Also, Fusobacterium could alter the tumor microenvironment (TME) significantly by myeloid-derived suppressor cells (MDSCs), tumor associated macrophages (TAMs), and tumor associated neutrophils (TANs) recruitment and local immune suppression. Herein, we provide an in-depth review of the relationship between Fusobacterium and colorectal cancer. In light of the emergence of microbiome-based therapeutics, potential therapies and preventive strategies for colorectal cancer related to Fusobacterium are also discussed.

Inhibition of Casein Kinase 2 Disrupts Differentiation of Myeloid Cells in Cancer and Enhances the Efficacy of Immunotherapy in Mice

The role of myeloid cells as regulators of tumor progression that significantly impact the efficacy of cancer immunotherapies makes them an attractive target for inhibition. Here we explore the effect of a novel, potent, and selective inhibitor of serine/threonine protein kinase casein kinase 2 (CK2) on modulating myeloid cells in the tumor microenvironment. Although inhibition of CK2 caused only a modest effect on dendritic cells in tumor-bearing mice, it substantially reduced the amount of polymorphonuclear myeloid-derived suppressor cells and tumor-associated macrophages. This effect was not caused by the induction of apoptosis, but rather by a block of differentiation. Our results implicated downregulation of CCAAT-enhancer binding protein-α in this effect. Although CK2 inhibition did not directly affect tumor cells, it dramatically enhanced the antitumor activity of immune checkpoint receptor blockade using anti-CTLA-4 antibody. These results suggest a potential role of CK2 inhibitors in combination therapies against cancer.Significance: These findings demonstrate the modulatory effects of casein kinase 2 inhibitors on myeloid cell differentiation in the tumor microenvironment, which subsequently synergize with the antitumor effects of checkpoint inhibitor CTLA4. Cancer Res; 78(19); 5644-55. ©2018 AACR.

Evaluation of Prenatal Exposure to Bisphenol Analogues on Development and Long-Term Health of the Mammary Gland in Female Mice

BACKGROUND

Continued efforts to phase out bisphenol A (BPA) from consumer products have been met with the challenges of finding safer alternatives.

OBJECTIVES

This study aimed to determine whether early-life exposure to BPA and its related analogues, bisphenol AF (BPAF) and bisphenol S (BPS), could affect female pubertal mammary gland development and long-term mammary health in mice.

METHODS

Timed pregnant CD-1 mice were exposed to vehicle, BPA (0.5, 5, 50 mg/kg), BPAF (0.05, 0.5, 5 mg/kg), or BPS (0.05, 0.5, 5 mg/kg) via oral gavage between gestation days 10–17. Mammary glands were collected from resulting female offspring at postnatal day (PND) 20, 28, 35, and 56, and at 3, 8, and 14 months for whole mount, histopathological evaluation, and quantitative real-time polymerase chain reaction (qPCR); serum steroid concentrations were also measured at these time points.

RESULTS

In the bisphenol-exposed mice, accelerated mammary gland development was evident during early puberty and persisted into adulthood. By late adulthood, mammary glands from bisphenol-exposed female offspring exhibited adverse morphology in comparison with controls; most prominent were undifferentiated duct ends, significantly more lobuloalveolar hyperplasia and perivascular inflammation, and various tumors, including adenocarcinomas. Effects were especially prominent in the BPAF 5 mg/kg and BPS 0.5 mg/kg groups. Serum steroid concentrations and mammary mRNA levels of Esr1, Pgr, Ar, and Gper1 were similar to controls.

CONCLUSIONS

These data demonstrate that prenatal exposure of mice to BPAF or BPS induced precocious development of the mammary gland, and that siblings were significantly more susceptible to spontaneous preneoplastic epithelial lesions and inflammation, with an incidence greater than that observed in vehicle- and BPA-exposed animals. https://doi.org/10.1289/EHP3189.

TRIENNIAL LACTATION SYMPOSIUM/BOLFA: Plasticity of mammary development in the prepubertal bovine mammary gland

Although peripubertal mammary development represents only a small fraction of the total mass of mammary parenchyma present in the udder at the end of gestation and into lactation, there is increasing evidence that the tissue foundations created in early life can affect future mammary development and function. Studies on expression of estrogen and progesterone receptors seem to confirm the relevance of these steroids in prepubertal mammary development, but connections with other growth factors, hormones, and local tissue factors remain elusive. Enhanced preweaning feeding in the bovine appears to enhance the capacity of mammary tissue to response to mammogenic stimulation. This suggests the possibility that improved early nutrition might allow for creation of stem or progenitor cell populations to better support the massive ductal growth and lobulo-alveolar development during gestation. Increasing evidence that immune cells are involved in mammary development suggests there are unexpected and poorly understood connections between the immune system and mammary development. This is nearly unexplored in ruminants. Development of new tools to identify, isolate, and characterize cell populations within the developing bovine mammary gland offer the possibility of identifying and perhaps altering populations of mammary stem cells or selected progenitor cells to modulate mammary development and, possibly, mammary function.

SNAIL1 action in tumor cells influences macrophage polarization and metastasis in breast cancer through altered GM-CSF secretion

The EMT inducer SNAIL1 regulates breast cancer metastasis and its expression in human primary breast tumor predicts for poor outcomes. During tumor progression SNAIL1 has multiple effects in tumor cells that can impact metastasis. An inflammatory tumor microenvironment also impacts metastasis and recently SNAIL1 has been implicated as modulating the secretion of cytokines that can influence the tumor immune infiltrate. Using a spontaneous genetic model of breast cancer metastasis and syngeneic orthotopic transplant experiments we show that the action of SNAIL1 in primary breast tumor cells is required for breast tumor growth and metastasis. It does so, in part, by regulating production of GM-CSF, IL1α, IL-6, and TNFα by breast cancer cells. The SNAIL1-dependent tumor cell secretome modulates the primary tumor-associated macrophage (TAM) polarization. GM-CSF alone modulates TAM polarization and impacts breast cancer metastasis in vivo. This study highlights another role for breast tumor SNAIL1 in cancer progression to metastasis-modulation of the immune microenvironment of primary breast tumors.

Peripheral inflammation/immune indicators of chemosensitivity and prognosis in breast cancer patients treated with neoadjuvant chemotherapy

INTRODUCTION

Neoadjuvant chemotherapy (NAC) has become a standard treatment for locally advanced breast cancer. The present study was designed to investigate the predictive value of different peripheral inflammation/immune biomarker responses to NAC and prognosis in breast cancer patients.

MATERIALS AND METHODS

A total of 180 breast cancer patients treated with NAC in the First Affiliated Hospital with Nanjing Medical University between January 2008 and March 2015 were enrolled in the study. The associations between inflammation/immune indicators and pathological complete response (pCR) were determined, and the prognostic value of inflammation/immune indicators was also evaluated.

RESULTS

In the univariate analysis, patients with a high pretreatment peripheral lymphocyte count (.2.06×109/L) showed a higher pCR rate than those with a low lymphocyte count (23.9% vs 10.4%, P=0.023). The pCR rate of patients with a neutrophil: lymphocyte ratio ≤2.15 was significantly higher than that of patients with a high neutrophil: lymphocyte ratio (20% vs 7.8%; P=0.03). However, multivariate analysis revealed that only the high lymphocyte count was predictive for pCR (odds ratio: 4.375, 95% CI: 1.429-13.392, P=0.010). In the survival analysis, patients with a higher neutrophil count (.2.65×109/L) were confirmed to have a shorter disease-free survival (hazard ratio: 4.322, 95% CI: 1.028-18.174, P=0.046), and the high neutrophil count was significantly associated with lymphovascular invasion (P=0.037).

CONCLUSION

We demonstrated that a high level of baseline peripheral lymphocyte count can be a predictor for high efficacy of NAC for breast cancer patients, and low baseline peripheral neutrophil count may contribute to the favorable disease-free survival.

Studies of Mast Cells: Adventures in Serendipity

Like many of us who had the great fortune to work with Bill Paul, my science life was immeasurably altered by my interactions with him. Although intimidating at first because of his stature in the immunology world, it was soon clear that he not only truly cared about the specific research we were doing together, but he wished to convey to his trainees an approach to science that was open, always questioning, and infinitely fun. His enthusiasm was infectious and after my training with him, despite stresses due to funding and publishing hurdles, I never regretted the path I took. My research took a sharp turn from the studies of adaptive immunity I had planned on pursuing after my fellowship with Bill to a life long quest to understand the wonders of the mast cell, a relatively rare innate immune cell. This came about because Bill’s curiosity and expectation of the unexpected allowed him to view, in retrospect, a rather mundane observation we made together involving a non-physiological transformed mast cell line as something that might be really interesting. I have never forgotten that lesson: Look at the data with an eye on the big picture. Sometimes the unexpected is more interesting than predicted results. His example in this regard was incredibly important when as an independent investigator a mistake in mouse sex determination led to unexpected and very confusing data. Yet, these data ultimately revealed a role for mast cells in male-specific protection in experimental autoimmune encephalomyelitis, the mouse model of multiple sclerosis. Bill’s influence in immunology is far-reaching and will continue to be felt as those of us who train our own students and post-doctoral fellows pass on his wisdom and approach to scientific research.

Th-POK regulates mammary gland lactation through mTOR-SREBP pathway

The Th-inducing POK (Th-POK, also known as ZBTB7B or cKrox) transcription factor is a key regulator of lineage commitment of immature T cell precursors. It is yet unclear the physiological functions of Th-POK besides helper T cell differentiation. Here we show that Th-POK is restrictedly expressed in the luminal epithelial cells in the mammary glands that is upregulated at late pregnancy and lactation. Lineage restrictedly expressed Th-POK exerts distinct biological functions in the mammary epithelial cells and T cells in a tissue-specific manner. Th-POK is not required for mammary epithelial cell fate determination. Mammary gland morphogenesis in puberty and alveologenesis in pregnancy are phenotypically normal in the Th-POK-deficient mice. However, Th-POK-deficient mice are defective in triggering the onset of lactation upon parturition with large cellular lipid droplets retained within alveolar epithelial cells. As a result, Th-POK knockout mice are unable to efficiently secret milk lipid and to nurse the offspring. Such defect is mainly attributed to the malfunctioned mammary epithelial cells, but not the tissue microenvironment in the Th-POK deficient mice. Th-POK directly regulates expression of insulin receptor substrate-1 (IRS-1) and insulin-induced Akt-mTOR-SREBP signaling. Th-POK deficiency compromises IRS-1 expression and Akt-mTOR-SREBP signaling in the lactating mammary glands. Conversely, insulin induces Th-POK expression. Thus, Th-POK functions as an important feed-forward regulator of insulin signaling in mammary gland lactation.

Therapeutic Effects of a Traditional Chinese Medicine Formula Plus Tamoxifen vs. Tamoxifen for the Treatment of Mammary Gland Hyperplasia: A Meta-Analysis of Randomized Trials

As a common disorder that accounts for over 70% of all breast disease cases, mammary gland hyperplasia (MGH) causes a severe problem for the quality of patients' life, and confers an increased risk of breast carcinoma. However, the etiology and pathogenesis of MGH remain unclear, and the safety and efficacy of current western drug therapy for MGH still need to be improved. Therefore, a meta-analysis was conducted by our team to determine whether a TCM formula named Ru-Pi-Xiao in combination with tamoxifen or Ru-Pi-Xiao treated alone can show more prominent therapeutic effects against MGH with fewer adverse reactions than that of tamoxifen. Studies published before June 2017 were searched based on standardized searching rules in several mainstream medical databases. A total of 27 articles with 4,368 patients were enrolled in this meta-analysis. The results showed that the combination of Ru-Pi-Xiao and tamoxifen could exhibit better therapeutic effects against MGH than that of tamoxifen (OR: 3.79; 95% CI: 3.09-4.65; P < 0.00001) with a lower incidence of adverse reactions (OR: 0.35; 95% CI: 0.28-0.43; P < 0.00001). The results also suggested that this combination could improve the level of progesterone (MD: 2.22; 95% CI: 1.72-2.71; P < 0.00001) and decrease the size of breast lump (MD: -0.67; 95% CI: -0.86 to -0.49; P < 0.00001) to a greater extent, which might provide a possible explanation for the pharmacodynamic mechanism of Ru-Pi-Xiao plus tamoxifen. In conclusion, Ru-Pi-Xiao and related preparations could be recommended as auxiliary therapy combined tamoxifen for the treatment of MGH.

Breast Cancer Immunotherapy: Facts and Hopes

Immunotherapy is revolutionizing the management of multiple solid tumors, and early data have revealed the clinical activity of programmed cell death-1/programmed death ligand-1 (PD-1/PD-L1) antagonists in small numbers of patients with metastatic breast cancer. Clinical activity appears more likely if the tumor is triple negative, PD-L1+, and/or harbors higher levels of tumor-infiltrating leukocytes. Responses to atezolizumab and pembrolizumab appear to be durable in metastatic triple-negative breast cancer (TNBC), suggesting that these agents may transform the lives of responding patients. Current clinical efforts are focused on developing immunotherapy combinations that convert nonresponders to responders, deepen those responses that do occur, and surmount acquired resistance to immunotherapy. Identifying biomarkers that can predict the potential for response to single-agent immunotherapy, identify the best immunotherapy combinations for a particular patient, and guide salvage immunotherapy in patients with progressive disease are high priorities for clinical development. Smart clinical trials testing rational immunotherapy combinations that include robust biomarker evaluations will accelerate clinical progress, moving us closer to effective immunotherapy for almost all patients with breast cancer. Clin Cancer Res; 24(3); 511-20. ©2017 AACR.

Genetic deletion of the Rho GEF Net1 impairs mouse macrophage motility and actin cytoskeletal organization

Macrophages are innate immune cells that constantly patrol an organism to fulfill protective and homeostatic roles. Previous studies have shown that Rho GTPase activity is required for macrophage mobility, yet the roles of upstream regulatory proteins controlling Rho GTPase function in these cells are not well defined. Previously we have shown that the RhoA GEF Net1 is required for human breast cancer cell motility and extracellular matrix invasion. To assess the role of Net1 in macrophage motility, we isolated bone marrow macrophage (BMM) precursors from wild type and Net1 knockout mice. Loss of Net1 did not affect the ability of BMM precursors to differentiate into mature macrophages in vitro, as measured by CD68 and F4/80 staining. However, Net1 deletion significantly reduced RhoA activation, F-actin accumulation, adhesion, and motility in these cells. Nevertheless, similar to RhoA/RhoB double knockout macrophages, Net1 deletion did not impair macrophage recruitment to the peritoneum in a mouse model of sterile inflammation. These data demonstrate that Net1 is an important regulator of RhoA signaling and motility in mouse macrophages in vitro, but that its function may be dispensable for macrophage recruitment to inflammatory sites in vivo.

TRIENNIAL LACTATION SYMPOSIUM/BOLFA: Dietary regulation of allometric ductal growth in the mammary glands

Although mammary gland growth and development in females is a lifelong process, it builds on isometric and allometric phases of mammary growth to establish a complex ductal network before and during puberty. Only then can other phases of branching and alveologenesis, differentiation, lactation, and involution proceed. Although the ductal network of various species differs in its histomorphology, all glands undergo a common phase of allometric growth when the mammary ducts penetrate into the supporting stromal microenvironment. Perhaps not surprisingly, different aspects of diet and nutrition can influence this allometric growth, either directly or indirectly. In this review, we outline some of the fundamental aspects of how allometric ductal growth in the mammary glands of various species is influenced by diet and nutrition and identify opportunities and questions for future investigation.

Cancer-Associated Fibroblasts Neutralize the Anti-tumor Effect of CSF1 Receptor Blockade by Inducing PMN-MDSC Infiltration of Tumors

Tumor-associated macrophages (TAM) contribute to all aspects of tumor progression. Use of CSF1R inhibitors to target TAM is therapeutically appealing, but has had very limited anti-tumor effects. Here, we have identified the mechanism that limited the effect of CSF1R targeted therapy. We demonstrated that carcinoma-associated fibroblasts (CAF) are major sources of chemokines that recruit granulocytes to tumors. CSF1 produced by tumor cells caused HDAC2-mediated downregulation of granulocyte-specific chemokine expression in CAF, which limited migration of these cells to tumors. Treatment with CSF1R inhibitors disrupted this crosstalk and triggered a profound increase in granulocyte recruitment to tumors. Combining CSF1R inhibitor with a CXCR2 antagonist blocked granulocyte infiltration of tumors and showed strong anti-tumor effects.

The Transcriptome of Estrogen-Independent Mammary Growth in Female Mice Reveals That Not All Mammary Glands Are Created Equally

Allometric growth of ducts in the mammary glands (MGs) is widely held to be estrogen dependent. We previously discovered that the dietary fatty acid trans-10, cis-12 conjugated linoleic acid (CLA) stimulates estrogen-independent allometric growth and terminal end bud formation in ovariectomized mice. Given the similar phenotype induced by estrogen and CLA, we investigated the shared and/or divergent mechanisms underlying these changes. We confirmed MG growth induced by CLA is temporally distinct from that elicited by estrogen. We then used RNA sequencing to compare the transcriptome of the MG during similar proliferative and morphological states. Both estrogen and CLA affected the genes involved in proliferation. The transcriptome for estrogen-treated mice included canonical estrogen-induced genes, including Pgr, Areg, and Foxa1. In contrast, their expression was unchanged by CLA. However, CLA, but not estrogen, altered expression of a unique set of inflammation-associated genes, consistent with stromal changes. This CLA-altered signature included increased expression of epidermal growth factor receptor (EGFR) pathway components, consistent with the demonstration that CLA-induced MG growth is EGFR dependent. Our findings highlight a unique role for diet-induced inflammation that underlies estrogen-independent MG development.

Regulatory T Cells Exhibit Distinct Features in Human Breast Cancer

Regulatory T (Treg) cells reside in lymphoid organs and barrier tissues where they control different types of inflammatory responses. Treg cells are also found in human cancers, and studies in animal models suggest that they contribute to cancer progression. However, properties of human intratumoral Treg cells and those present in corresponding normal tissue remain largely unknown. Here, we analyzed features of Treg cells in untreated human breast carcinomas, normal mammary gland, and peripheral blood. Tumor-resident Treg cells were potently suppressive and their gene-expression pattern resembled that of normal breast tissue, but not of activated peripheral blood Treg cells. Nevertheless, a number of cytokine and chemokine receptor genes, most notably CCR8, were upregulated in tumor-resident Treg cells in comparison to normal tissue-resident ones. Our studies suggest that targeting CCR8 for the depletion of tumor-resident Treg cells might represent a promising immunotherapeutic approach for the treatment of breast cancer.

Age, estrogen, and immune response in breast adenocarcinoma and adjacent normal tissue

Chronic inflammation promotes breast tumor growth and invasion by accelerating angiogenesis and tissue remodeling in the tumor microenvironment. There is a complex relationship between inflammation and estrogen, which drives the growth of 70 percent of breast tumors. While low levels of estrogen exposure stimulate macrophages and other inflammatory cell populations, very high levels are immune suppressive. Breast tumor incidence is increased by obesity and age, which interact to influence inflammatory cell populations in normal breast tissue. To characterize the impact of these factors on tumors and the tumor microenvironment, we measured gene expression in 195 breast adenocarcinomas and matched adjacent normal breast tissue samples collected at Akershus University Hospital (AHUS). Age and Body Mass Index (BMI) were independently associated with inflammation in adjacent normal tissue but not tumors. Estrogen Receptor (ER)-negative tumors had elevated macrophage expression compared with matched normal tissue, but ER-positive tumors showed an unexpected decrease in macrophage expression. We found an inverse relationship between the increase in tumor estrogen pathway expression compared with adjacent normal tissue and tumor macrophage score. We validated this finding in 126 breast tumor-normal pairs from the previously published METABRIC cohort. We developed a novel statistic, the Rewiring Coefficient, to quantify the rewiring of gene co-expression networks at the level of individual genes. Differential correlation analysis demonstrated distinct pathways were rewired during tumorigenesis. Our data support an immune suppressive effect of high doses of estrogen signaling in breast tumor microenvironment, suggesting that this effect contributes to the greater presence of prognostic and therapeutically relevant immune cells in ER-negative tumors.

The innate and adaptive infiltrating immune systems as targets for breast cancer immunotherapy

A cancer cell-centric view has long dominated the field of cancer biology. Research efforts have focussed on aberrant cancer cell signalling pathways and on changes to cancer cell DNA. Mounting evidence demonstrates that many cancer-associated cell types within the tumour stroma co-evolve and support tumour growth and development, greatly modifying cancer cell behaviour, facilitating invasion and metastasis and controlling dormancy and sensitivity to drug therapy. Thus, these stromal cells represent potential targets for cancer therapy. Among these cell types, immune cells have emerged as a promising target for therapy. The adaptive and the innate immune system play an important role in normal mammary development and breast cancer. The number of infiltrating adaptive immune system cells with tumour-rejecting capacity, primarily, T lymphocytes, is lower in breast cancer compared with other cancer types, but infiltration occurs in a large proportion of cases. There is strong evidence demonstrating the importance of the immunosuppressive role of the innate immune system during breast cancer progression. A consideration of components of both the innate and the adaptive immune system is essential for the design and development of immunotherapies in breast cancer. In this review, we focus on the importance of immunosuppressive myeloid-derived suppressor cells (MDSCs) as potential targets for breast cancer therapy.

Carcinogenesis mechanisms of Fusobacterium nucleatum

Transformed cells of cancers may be related to stromal cells, immune cells, and some bacteria such as Fusobacterium nucleatum. This review aimed to evaluate carcinogenesis mechanisms of Fusobacterium spp. in the oral cavity, pancreatic and colorectal cancers. These cancers are the three of the ten most prevalence cancer in the worldwide. Recent findings demonstrated that F. nucleatum could be considered as the risk factor for these cancers. The most important carcinogenesis mechanisms of F. nucleatum are chronic infection, interaction of cell surface molecules of these bacteria with immune system and stromal cells, immune evasion and immune suppression. However, there are some uncertainty carcinogenesis mechanisms about these bacteria, but this review evaluates almost all the known mechanisms. Well-characterized virulence factors of F. nucleatum such as FadA, Fap2, LPS and cell wall extracts may act as effector molecules in the shift of normal epithelial cells to tumor cells. These molecules may provide new targets, drugs, and strategies for therapeutic intervention.

Role of Prolactin in Promotion of Immune Cell Migration into the Mammary Gland

Immune cells in the mammary gland play a number of important roles, including protection against infection during lactation and, after passing into milk, modulation of offspring immunity. However, little is known about the mechanism of recruitment of immune cells to the lactating gland in the absence of infection. Given the importance of prolactin to other aspects of lactation, we hypothesized it would also play a role in immune cell recruitment. Prolactin treatment of adult female mice for a period equivalent to pregnancy and the first week of lactation increased immune cell flux through the mammary gland, as reflected in the number of immune cells in mammary gland-draining, but not other lymph nodes. Conditioned medium from luminal mammary epithelial HC11 cell cultures was chemo-attractive to CD4+ and CD8+ T cells, CD4+ and CD8+ memory T cells, B cells, macrophages, monocytes, eosinophils, and neutrophils. Prolactin did not act as a direct chemo-attractant, but through effects on luminal mammary epithelial cells, increased the chemo-attractant properties of conditioned medium. Macrophages and neutrophils constitute the largest proportion of cells in milk from healthy glands. Depletion of CCL2 and CXCL1 from conditioned medium reduced chemo-attraction of monocytes and neutrophils, and prolactin increased expression of these two chemokines in mammary epithelial cells. We conclude that prolactin is an important player in the recruitment of immune cells to the mammary gland both through its activities to increase epithelial cell number as well as production of chemo-attractants on a per cell basis.

Cold-inducible RNA binding protein in mouse mammary gland development

RNA binding proteins (RBPs) regulate gene expression by controlling mRNA export, translation, and stability. When altered, some RBPs allow cancer cells to grow, survive, and metastasize. Cold-inducible RNA binding protein (CIRP) is overexpressed in a subset of breast cancers, induces proliferation in breast cancer cell lines, and inhibits apoptosis. Although studies have begun to examine the role of CIRP in breast and other cancers, its role in normal breast development has not been assessed. We generated a transgenic mouse model overexpressing human CIRP in the mammary epithelium to ask if it plays a role in mammary gland development. Effects of CIRP overexpression on mammary gland morphology, cell proliferation, and apoptosis were studied from puberty through pregnancy, lactation and weaning. There were no gross effects on mammary gland morphology as shown by whole mounts. Immunohistochemistry for the proliferation marker Ki67 showed decreased proliferation during the lactational switch (the transition from pregnancy to lactation) in mammary glands from CIRP transgenic mice. Two markers of apoptosis showed that the transgene did not affect apoptosis during mammary gland involution. These results suggest a potential in vivo function in suppressing proliferation during a specific developmental transition.

New potential beneficial effects of actein, a triterpene glycoside isolated from Cimicifuga species, in breast cancer treatment

Actein is a triterpene glycoside isolated from the rhizomes of Cimicifuga foetida (Chinese herb “shengma”) which could inhibit the growth of breast cancer cells. Nevertheless, the effect of actein on angiogenesis, which is an essential step for tumor growth and metastasis, has never been reported. Hence, this study aimed to investigate the in vitro and in vivo effects of actein on angiogenesis using human microvascular endothelial cells (HMEC-1), matrigel plug and tumor-bearing mouse models. Our results showed that actein significantly inhibited the proliferation, reduced the migration and motility of endothelial cells, and it could suppress the protein expressions of VEGFR1, pJNK and pERK, suggesting that JNK/ERK pathways were involved. In vivo results showed that oral administration of actein at 10 mg/kg for 7 days inhibited blood vessel formation in the growth factor-containing matrigel plugs. Oral actein treatments (10–15 mg/kg) for 28 days resulted in decreasing mouse 4T1 breast tumor sizes and metastasis to lungs and livers. The apparent reduced angiogenic proteins (CD34 and Factor VIII) expressions and down-regulated metastasis-related VEGFR1 and CXCR4 gene expressions were observed in breast tumors. Our novel findings provide insights into the use of actein for development of anti-angiogenic agents for breast cancer.

In-silico insights on the prognostic potential of immune cell infiltration patterns in the breast lobular epithelium

Scattered inflammatory cells are commonly observed in mammary gland tissue, most likely in response to normal cell turnover by proliferation and apoptosis, or as part of immunosurveillance. In contrast, lymphocytic lobulitis (LLO) is a recurrent inflammation pattern, characterized by lymphoid cells infiltrating lobular structures, that has been associated with increased familial breast cancer risk and immune responses to clinically manifest cancer. The mechanisms and pathogenic implications related to the inflammatory microenvironment in breast tissue are still poorly understood. Currently, the definition of inflammation is mainly descriptive, not allowing a clear distinction of LLO from physiological immunological responses and its role in oncogenesis remains unclear. To gain insights into the prognostic potential of inflammation, we developed an agent-based model of immune and epithelial cell interactions in breast lobular epithelium. Physiological parameters were calibrated from breast tissue samples of women who underwent reduction mammoplasty due to orthopedic or cosmetic reasons. The model allowed to investigate the impact of menstrual cycle length and hormone status on inflammatory responses to cell turnover in the breast tissue. Our findings suggested that the immunological context, defined by the immune cell density, functional orientation and spatial distribution, contains prognostic information previously not captured by conventional diagnostic approaches.

Acquired Resistance to Clinical Cancer Therapy: A Twist in Physiological Signaling

Although modern therapeutic strategies have brought significant progress to cancer care in the last 30 years, drug resistance to targeted monotherapies has emerged as a major challenge. Aberrant regulation of multiple physiological signaling pathways indispensable for developmental and metabolic homeostasis, such as hyperactivation of pro-survival signaling axes, loss of suppressive regulations, and impaired functionalities of the immune system, have been extensively investigated aiming to understand the diversity of molecular mechanisms that underlie cancer development and progression. In this review, we intend to discuss the molecular mechanisms of how conventional physiological signal transduction confers to acquired drug resistance in cancer patients. We will particularly focus on protooncogenic receptor kinase inhibition-elicited tumor cell adaptation through two major core downstream signaling cascades, the PI3K/Akt and MAPK pathways. These pathways are crucial for cell growth and differentiation and are frequently hyperactivated during tumorigenesis. In addition, we also emphasize the emerging roles of the deregulated host immune system that may actively promote cancer progression and attenuate immunosurveillance in cancer therapies. Understanding these mechanisms may help to develop more effective therapeutic strategies that are able to keep the tumor in check and even possibly turn cancer into a chronic disease.

Key Characteristics of Carcinogens as a Basis for Organizing Data on Mechanisms of Carcinogenesis

BACKGROUND

A recent review by the International Agency for Research on Cancer (IARC) updated the assessments of the > 100 agents classified as Group 1, carcinogenic to humans (IARC Monographs Volume 100, parts A-F). This exercise was complicated by the absence of a broadly accepted, systematic method for evaluating mechanistic data to support conclusions regarding human hazard from exposure to carcinogens.

OBJECTIVES AND METHODS

IARC therefore convened two workshops in which an international Working Group of experts identified 10 key characteristics, one or more of which are commonly exhibited by established human carcinogens.

DISCUSSION

These characteristics provide the basis for an objective approach to identifying and organizing results from pertinent mechanistic studies. The 10 characteristics are the abilities of an agent to 1) act as an electrophile either directly or after metabolic activation; 2) be genotoxic; 3) alter DNA repair or cause genomic instability; 4) induce epigenetic alterations; 5) induce oxidative stress; 6) induce chronic inflammation; 7) be immunosuppressive; 8) modulate receptor-mediated effects; 9) cause immortalization; and 10) alter cell proliferation, cell death, or nutrient supply.

CONCLUSION

We describe the use of the 10 key characteristics to conduct a systematic literature search focused on relevant end points and construct a graphical representation of the identified mechanistic information. Next, we use benzene and polychlorinated biphenyls as examples to illustrate how this approach may work in practice. The approach described is similar in many respects to those currently being implemented by the U.S. EPA's Integrated Risk Information System Program and the U.S. National Toxicology Program.

CITATION

Smith MT, Guyton KZ, Gibbons CF, Fritz JM, Portier CJ, Rusyn I, DeMarini DM, Caldwell JC, Kavlock RJ, Lambert P, Hecht SS, Bucher JR, Stewart BW, Baan R, Cogliano VJ, Straif K. 2016. Key characteristics of carcinogens as a basis for organizing data on mechanisms of carcinogenesis. Environ Health Perspect 124:713-721; http://dx.doi.org/10.1289/ehp.1509912.

Human breast cancer biopsies induce eosinophil recruitment and enhance adjacent cancer cell proliferation

Chronic inflammation is known to facilitate cancer progression and metastasis. Less is known about the effect of acute inflammation within the tumor microenvironment, resulting from standard invasive procedures. Recent studies in mouse models have shown that the acute inflammatory response triggered by a biopsy in mammary cancer increases the frequency of distal metastases. Although tumor biopsies are part of the standard clinical practice in breast cancer diagnosis, no studies have reported their effect on inflammatory response. The objective of this study is to (1) determine whether core needle biopsies in breast cancer patients trigger an inflammatory response, (2) characterize the type of inflammatory response present, and (3) evaluate the potential effect of any acute inflammatory response on residual tumor cells. The biopsy wound site was identified in the primary tumor resection tissue samples from breast cancer patients. The inflammatory response in areas adjacent (i.e., immediately around previous biopsy site) and distant to the wound biopsy was investigated by histology and immunohistochemistry analysis. Proliferation of tumor cells was also assayed. We demonstrate that diagnostic core needle biopsies trigger a selective recruitment of inflammatory cells at the site of the biopsy, and they persist for extended periods of time. While macrophages were part of the inflammatory response, an unexpected accumulation of eosinophils at the edge of the biopsy wound was also identified. Importantly, we show that biopsy causes an increase in the proliferation rate of tumor cells located in the area adjacent to the biopsy wound. Diagnostic core needle biopsies in breast cancer patients do induce a unique acute inflammatory response within the tumor microenvironment and have an effect on the surrounding tumor cells. Therefore, biopsy-induced inflammation could have an impact on residual tumor cell progression and/or metastasis in human breast cancer. These findings may carry relevance in the clinical management of breast cancer.

Beneficial bacteria inhibit cachexia

Muscle wasting, known as cachexia, is a debilitating condition associated with chronic inflammation such as during cancer. Beneficial microbes have been shown to optimize systemic inflammatory tone during good health; however, interactions between microbes and host immunity in the context of cachexia are incompletely understood. Here we use mouse models to test roles for bacteria in muscle wasting syndromes. We find that feeding of a human commensal microbe, Lactobacillus reuteri, to mice is sufficient to lower systemic indices of inflammation and inhibit cachexia. Further, the microbial muscle-building phenomenon extends to normal aging as wild type animals exhibited increased growth hormone levels and up-regulation of transcription factor Forkhead Box N1 [FoxN1] associated with thymus gland retention and longevity. Interestingly, mice with a defective FoxN1 gene (athymic nude) fail to inhibit sarcopenia after L. reuteri therapy, indicating a FoxN1-mediated mechanism. In conclusion, symbiotic bacteria may serve to stimulate FoxN1 and thymic functions that regulate inflammation, offering possible alternatives for cachexia prevention and novel insights into roles for microbiota in mammalian ontogeny and phylogeny.

The Immunology of Breast Development

The immune system is not normally viewed as a regulator of breast development. However, in this issue of Developmental Cell, Plaks et al. (2015) reveal that antigen-presenting cells and T cells have a key role in controlling the development of the mammary gland's epithelial ductal network.

Targeted complement inhibition and microvasculature in transplants: a therapeutic perspective

Active complement mediators play a key role in graft-versus-host diseases, but little attention has been given to the angiogenic balance and complement modulation during allograft acceptance. The complement cascade releases the powerful proinflammatory mediators C3a and C5a anaphylatoxins, C3b, C5b opsonins and terminal membrane attack complex into tissues, which are deleterious if unchecked. Blocking complement mediators has been considered to be a promising approach in the modern drug discovery plan, and a significant number of therapeutic alternatives have been developed to dampen complement activation and protect host cells. Numerous immune cells, especially macrophages, develop both anaphylatoxin and opsonin receptors on their cell surface and their binding affects the macrophage phenotype and their angiogenic properties. This review discusses the mechanism that complement contributes to angiogenic injury, and the development of future therapeutic targets by antagonizing activated complement mediators to preserve microvasculature in rejecting the transplanted organ.

Localization and quantitation of macrophages, mast cells, and eosinophils in the developing bovine mammary gland

Prepubertal mammary development involves elongation and branching of ducts and stromal tissue remodeling. This process is highly regulated and in mice is known to be affected by the presence of innate immune cells. Whether or not such immune cells are present or involved in bovine mammary development is unknown. For the first time, we determined the presence, location (relative to mammary ductal structures), and changes in numbers of eosinophils, mast cells, and macrophages in prepubertal bovine mammary tissue, and evaluated the effects of age, ovariectomy, and exogenous estrogen on numbers of each cell type. Chemical stains and immunofluorescence were used to identify the 3 cell types in formalin-fixed, paraffin-embedded mammary tissue from prepubertal female calves from 3 archived tissue sets. The ontogeny tissue set included samples of mammary tissue from female calves (n=4/wk) from birth to 6 wk of age. The ovary tissue set contained samples from ovary intact and ovariectomized heifers allowing us to investigate the influence of the ovaries on immune cells in the developing mammary gland in prepubertal heifers. Nineteen animals were intact or ovariectomized 30 d before sampling; they were 90, 120, or 150 d old at the time of sampling. A third tissue set, the estrogen set, allowed us to determine the effect of exogenous estrogen on innate immune cells in the gland. Eosinophils were identified via Luna staining, mast cells by May-Grunwald Giemsa staining, and macrophages with immunofluorescence. Key findings were that more eosinophils and mast cells were observed in near versus far stroma in the ontogeny and ovary tissue sets but not estrogen. More macrophages were observed in near versus far stroma in ontogeny animals. Eosinophils were more abundant in the younger animals, and fewer macrophages tended to be observed in ovariectomized heifers as compared with intact heifers and estrogen treatment resulted in a reduction in cell numbers. In summary, we show for the first time that innate immune cells are present in prepubertal bovine mammary tissue, localization varies by immune cell type, and abundance is related to proximity of epithelial structures and physiological state. We suggest a likely role for these cells in control of bovine mammary growth and ductal development.

The pancreatic cancer secreted REG4 promotes macrophage polarization to M2 through EGFR/AKT/CREB pathway

In the periphery of pancreatic ductal adenocarcinoma (PDAC), high accumulation of tumor-associated macrophages (TAMs), which exhibit M2 phenotype, has been shown to be correlated with extra-pancreatic invasion, lymph vessel invasion, lymph node involvement and shortened survival time. However, mechanisms by which tumor cells educate and reprogram TAMs remain largely unclear. The phenotype of TAMs in PDAC tissues was confirmed by immunofluoresence and confocal microscopy. Human CD14+ monocytes were incubated with recombinant human REG4 (rREG4) before being stimulated with LPS and IL-10 and IL-6 were measured with ELISA. A panel of M1 and M2 genes were measured by quantitative real-time PCR. Panc1, AsPC1 and BxPC3 cells were cultured in the conditioned medium (CM) and treated with REG4. The macrophages were infected with CREB shRNA or cultured by the CM of Panc1 cells infected with REG4 shRNA. The expression of CD163, CD206 and REG4 and the phosphorylation levels of epidermal growth factor receptor (EGFR), AKT and cAMP response element-binding protein (CREB) in cells were assessed with western blotting. Cell proliferation and invasiveness were also assessed. The rREG4 or the conditioned medium of Panc1 cells which secreted REG4 induced the polarization macrophages to M2 phenotype. Treatment of human macrophages with REG4 resulted in phosphorylation of EGFR, AKT and CREB. The latter was responsible for REG4-mediated macrophage polarization to M2. The conditioned medium of macrophages treated with rREG4 promoted the proliferation and invasion of pancreatic cancer cell lines. REG4, overexpressed in PDAC and secreted by cancer cells, promoted macrophage polarization to M2, through at least in part, activation of ERK1/2 and CREB and changed the microenvironment to facilitate cancer growth and metastasis.

Adaptive Immune Regulation of Mammary Postnatal Organogenesis

Postnatal organogenesis occurs in an immune competent environment and is tightly controlled by interplay between positive and negative regulators. Innate immune cells have beneficial roles in postnatal tissue remodeling, but roles for the adaptive immune system are currently unexplored. Here we show that adaptive immune responses participate in the normal postnatal development of a non-lymphoid epithelial tissue. Since the mammary gland (MG) is the only organ developing predominantly after birth, we utilized it as a powerful system to study adaptive immune regulation of organogenesis. We found that antigen-mediated interactions between mammary antigen-presenting cells and interferon-γ (IFNγ)-producing CD4+ T helper 1 cells participate in MG postnatal organogenesis as negative regulators, locally orchestrating epithelial rearrangement. IFNγ then affects luminal lineage differentiation. This function of adaptive immune responses, regulating normal development, changes the paradigm for studying players of postnatal organogenesis and provides insights into immune surveillance and cancer transformation.

FLT1 signaling in metastasis-associated macrophages activates an inflammatory signature that promotes breast cancer metastasis

Although the link between inflammation and cancer initiation is well established, its role in metastatic diseases, the primary cause of cancer deaths, has been poorly explored. Our previous studies identified a population of metastasis-associated macrophages (MAMs) recruited to the lung that promote tumor cell seeding and growth. Here we show that FMS-like tyrosine kinase 1 (Flt1, also known as VEGFR1) labels a subset of macrophages in human breast cancers that are significantly enriched in metastatic sites. In mouse models of breast cancer pulmonary metastasis, MAMs uniquely express FLT1. Using several genetic models, we show that macrophage FLT1 signaling is critical for metastasis. FLT1 inhibition does not affect MAM recruitment to metastatic lesions but regulates a set of inflammatory response genes, including colony-stimulating factor 1 (CSF1), a central regulator of macrophage biology. Using a gain-of-function approach, we show that CSF1-mediated autocrine signaling in MAMs is downstream of FLT1 and can restore the tumor-promoting activity of FLT1-inhibited MAMs. Thus, CSF1 is epistatic to FLT1, establishing a link between FLT1 and inflammatory responses within breast tumor metastases. Importantly, FLT1 inhibition reduces tumor metastatic efficiency even after initial seeding, suggesting that these pathways represent therapeutic targets in metastatic disease.

Current Issues and Clinical Evidence in Tumor-Infiltrating Lymphocytes in Breast Cancer

With the advance in personalized therapeutic strategies in patients with breast cancer, there is an increasing need for biomarker-guided therapy. Although the immunogenicity of breast cancer has not been strongly considered in research or practice, tumor-infiltrating lymphocytes (TILs) are emerging as biomarkers mediating tumor response to treatments. Earlier studies have provided evidence that the level of TILs has prognostic value and the potential for predictive value, particularly in triple-negative and human epidermal growth factor receptor 2–positive breast cancer. Moreover, the level of TILs has been associated with treatment outcome in patients undergoing neoadjuvant chemotherapy. To date, no standardized methodology for measuring TILs has been established. In this article, we review current issues and clinical evidence for the use of TILs in breast cancer.

Complement and macrophage crosstalk during process of angiogenesis in tumor progression

The complement system, which contains some of the most potent pro-inflammatory mediators in the tissue including the anaphylatoxins C3a and C5a are the vital parts of innate immunity. Complement activation seems to play a more critical role in tumor development, but little attention has been given to the angiogenic balance of the activated complement mediators and macrophage polarization during tumor progression. The tumor growth mainly supported by the infiltration of M2- tumor-associated macrophages, and high levels of C3a and C5a, whereas M1-macrophages contribute to immune-mediated tumor suppression. Macrophages express a cognate receptors for both C3a and C5a on their cell surface, and specific binding of C3a and C5a affects the functional modulation and angiogenic properties. Activation of complement mediators induce angiogenesis, favors an immunosuppressive microenvironment, and activate cancer-associated signaling pathways to assist chronic inflammation. In this review manuscript, we highlighted the specific roles of complement activation and macrophage polarization during uncontrolled angiogenesis in tumor progression, and therefore blocking of complement mediators would be an alternative therapeutic option for treating cancer.

The role of inflammation in progression of breast cancer: Friend or foe? (Review)

There is a growing interest in the role of the microenvironment in cancer, however, it has been known for over one hundred years that the immune system plays a prominent role in cancer. Recent decades have revealed more and more data on how our own host response to cancer cells can help or hinder progression of the disease. Despite all this work it is surprising how little is known about the role of the immune system in human breast cancer development, as compared to other cancers. Recent successes of PD-1 blockade in treating multiple cancers, and new developments with other immune targets such as CTLA-4 and CSF-1 inhibitors, highlight that it is becoming ever more important that we understand the complexity of the immune and inflammatory systems in the development and progression of breast cancer. With this knowledge it may be possible to not only target therapy but also more accurately predict those patients that truly need it. This review summarises some of the most significant findings for the role of the immune system and inflammatory response in breast cancer progression. Focusing on how the inflammatory microenvironment may be involved in the progression of pre-invasive ductal carcinoma in situ to invasive breast cancer. It will also discuss the use of immune markers as diagnostic and prognostic tools and summarise the state of the art of immune-therapeutics in breast cancer treatment.