Semaphorin7A promotes tumor growth and exerts a pro-angiogenic effect in macrophages of mammary tumor-bearing mice

Semaphorins in tumor microenvironment: Biological mechanisms and therapeutic progress

Hallmark features of the tumor microenvironment include immune cells, stromal cells, blood vessels, and extracellular matrix (ECM), providing a conducive environment for the growth and survival of tumors. Recent advances in the understanding of cancer biology have highlighted the functional role of semaphorins (SEMAs). SEMAs are a large and diverse family of widely expressed secreted and membrane-binding proteins, which were initially implicated in axon guidance and neural development. However, it is now clear that they are widely expressed beyond the nervous system and participate in regulating immune responses and cancer progression. In fact, accumulating evidence disclosed that different SEMAs can either stimulate or restrict tumor progression, some of which act as important regulators of tumor angiogenesis. Conversely, limited information is known about the functional relevance of SEMA signals in TME. In this setting, we systematically elaborate the role SEMAs and their major receptors played in characterized components of TME. Furthermore, we provide a convergent view of current SEMAs pharmacological progress in clinical treatment and also put forward their potential application value and clinical prospects in the future.

FUT8-mediated aberrant N-glycosylation of SEMA7A promotes head and neck squamous cell carcinoma progression

SEMA7A belongs to the Semaphorin family and is involved in the oncogenesis and tumor progression. Aberrant glycosylation has been intricately linked with immune escape and tumor growth. SEMA7A is a highly glycosylated protein with five glycosylated sites. The underlying mechanisms of SEMA7A glycosylation and its contribution to immunosuppression and tumorigenesis are unclear. Here, we identify overexpression and aberrant N-glycosylation of SEMA7A in head and neck squamous cell carcinoma, and elucidate fucosyltransferase FUT8 catalyzes aberrant core fucosylation in SEMA7A at N-linked oligosaccharides (Asn 105, 157, 258, 330, and 602) via a direct protein‒protein interaction. A glycosylated statue of SEMA7A is necessary for its intra-cellular trafficking from the cytoplasm to the cytomembrane. Cytokine EGF triggers SEMA7A N-glycosylation through increasing the binding affinity of SEMA7A toward FUT8, whereas TGF-β1 promotes abnormal glycosylation of SEMA7A via induction of epithelial-mesenchymal transition. Aberrant N-glycosylation of SEMA7A leads to the differentiation of CD8+ T cells along a trajectory toward an exhausted state, thus shaping an immunosuppressive microenvironment and being resistant immunogenic cell death. Deglycosylation of SEMA7A significantly improves the clinical outcome of EGFR-targeted and anti-PD-L1-based immunotherapy. Finally, we also define RBM4, a splice regulator, as a downstream effector of glycosylated SEMA7A and a pivotal mediator of PD-L1 alternative splicing. These findings suggest that targeting FUT8-SEMA7A axis might be a promising strategy for improving antitumor responses in head and neck squamous cell carcinoma patients.

Adiponectin Receptor Agonist Effectively Suppresses Hepatocellular Carcinoma Growth

Hepatocellular carcinoma (HCC) is the second lethal cancer. Short overall survival, low five-year survival rate, and unimproved treatment efficacy urge the need to improve HCC prognosis. Adiponectin is key protector against cancer and hepatic abnormalities. Hypoadiponectinemia occurs in and promotes carcinogenesis and hepatic diseases. Adiponectin reactivation by different methods showed impressive effect against cancer and hepatic diseases. Recently, AdipoRon, an adiponectin receptor agonist, can interact with both Adiponectin receptors. AdipoRon showed promising anti-cancer effect in some cancers, but no study on HCC yet. The in vitro effect of AdipoRon on HCC was investigated by cell viability, migration, invasion, colony formation and apoptosis assays. The signalling alteration was determined by RT-qPCR and Western blot. The effect of treatment was interpreted by comparison between treatments and control. The difference between two cell lines was relatively compared. Our results showed significant in vitro anti-cancer effect of AdipoRon via AMPK- and dose-dependent manner. Huh7 cells showed a lower level of AdipoR1/2 and a superior proliferation and aggressiveness, compared to Hep3B. In addition, Huh7 cells were more sensitive to AdipoRon treatment (lower IC50, less cell growth, migration, invasion and colonies upon AdipoRon treatment) than Hep3B cells. In conclusion, AdipoRon effectively inhibited HCC growth and invasiveness in vitro. The deficient expression of adiponectin receptors affects efficacy of AdipoRon and aggressiveness of HCC cells.

Semaphorin 7a aggravates TGF-β1-induced airway EMT through the FAK/ERK1/2 signaling pathway in asthma

Background

TGF-β1 can induce epithelial-mesenchymal transition (EMT) in primary airway epithelial cells (AECs). Semaphorin7A (Sema7a) plays a crucial role in regulating immune responses and initiating and maintaining transforming growth factor β1 TGF-β1-induced fibrosis.

Objective

To determine the expression of Sema7a, in serum isolated from asthmatics and non-asthmatics, the role of Sema7a in TGF-β1 induced proliferation, migration and airway EMT in human bronchial epithelial cells (HBECs) in vitro.

Methods

The concentrations of Sema7a in serum of asthmatic patients was detected by enzyme-linked immunosorbent assay (ELISA). The expressions of Sema7a and integrin-β1 were examined using conventional western blotting and real-time quantitative PCR (RT-PCR). Interaction between the Sema7a and Integrin-β1 was detected using the Integrin-β1 blocking antibody (GLPG0187). The changes in EMT indicators were performed by western blotting and immunofluorescence, as well as the expression levels of phosphorylated Focal-adhesion kinase (FAK) and Extracellular-signal-regulated kinase1/2 (ERK1/2) were analyzed by western blot and their mRNA expression was determined by RT-PCR.

Results

We described the first differentially expressed protein of sema7a, in patients with diagnosed bronchial asthma were significantly higher than those of healthy persons (P<0.05). Western blotting and RT-PCR showed that Sema7a and Integrin-β1 expression were significantly increased in lung tissue from the ovalbumin (OVA)-induced asthma model. GLPG0187 inhibited TGF-β1-mediated HBECs EMT, proliferation and migration, which was associated with Focal-adhesion kinase (FAK) and Extracellular-signal-regulated kinase1/2 (ERK1/2) phosphorylation.

Conclusion

Sema7a may play an important role in asthma airway remodeling by inducing EMT. Therefore, new therapeutic approaches for the treatment of chronic asthma, could be aided by the development of agents that target the Sema7a.

Serum Sema7A is increased in patients with acute aortic dissection

BACKGROUND

To observe the level of serum Sema7A in acute aortic dissection (AAD) and its diagnostic value for AAD.

RESEARCH DESIGN AND METHODS

Patients with sudden chest pain including AAD, acute myocardial infarction (AMI) or pulmonary embolism (PE) were enrolled. Patients without chest pain or cardiovascular diseases were included as the controls. Serum Sema7A and plasma D-dimer were detected and compared in each group.

RESULTS

85 AAD patients, 55 AMI patients, 15 PE patients, and 30 controls were enrolled. The concentration of Serum Sema7A in the AAD group was significantly higher than that in the control, AMI and PE group. Serum Sema7A was positively correlated with D-dimer. In AAD patients who underwent invasive intervention therapy, serum Sema7A levels were significantly decreased after the intervention. Serum Sema7A was an independent risk factor for the presence of AAD. The areas under the ROC curve of Sema7A and D-dimer for differential diagnosis of AAD from other chest pain disorders were 0.842 (0.776, 0.909) and 0.788 (0.714, 0.862), respectively.

CONCLUSIONS

Sema7A is highly expressed in patients with AAD. Sema7A might be a valuable biomarker for the early diagnosis of AAD and has the potential to differentiate AAD from AMI and PE.

Semaphorins in immune cell function, inflammatory and infectious diseases

The Semaphorin family is a group of proteins studied broadly for their functions in nervous systems. They consist of eight subfamilies ubiquitously expressed in vertebrates, invertebrates, and viruses and exist in membrane-bound or secreted forms. Emerging evidence indicates the relevance of semaphorins outside the nervous system, including angiogenesis, cardiogenesis, osteoclastogenesis, tumour progression, and, more recently, the immune system. This review provides a broad overview of current knowledge on the role of semaphorins in the immune system, particularly its involvement in inflammatory and infectious diseases, including chlamydial infections.

Emerging roles and mechanisms of semaphorins activity in cancer

Semaphorins are regulatory molecules that are linked to the modulation of several cancer processes, such as angiogenesis, cancer cell invasiveness and metastasis, tumor growth, as well as cancer cell survival. Semaphorin (SEMA) activity depends on the cancer histotypes and their particularities. In broad terms, the effects of SEMAs result from their interaction with specific receptors/co-receptors - Plexins, Neuropilins and Integrins - and the subsequent effects upon the downstream effectors (e.g. PI3K/AKT, MAPK/ERK). The present article serves as an integrative review work, discussing the broad implications of semaphorins in cancer, focusing on cell proliferation/survival, angiogenesis, invasion, metastasis, stemness, and chemo-resistance/response whilst highlighting their heterogeneity as a family. Herein, we emphasized that semaphorins are largely implicated in cancer progression, interacting with the tumor microenvironment components. Whilst some SEMAs (e.g. SEMA3A, SEMA3B) function widely as tumor suppressors, others (e.g. SEMA3C) act as pro-tumor semaphorins. The differences observed in terms of the biological structure of SEMAs and the particularities of each cancer histotypes require that each semaphorin be viewed as a unique entity, and its roles must be researched accordingly. A more in-depth and comprehensive view of the molecular mechanisms that promote and sustain the malignant behavior of cancer cells is of utmost importance.

Comparative transcriptomic analysis and genome-wide characterization of the Semaphorin family reveal the potential mechanism of angiogenesis around embryo in ovoviviparous black rockfish (Sebastes schlegelii)

To guarantee the quality and survival rate of their offspring, ovoviviparous teleost evolved special characteristics of in vivo fertilization and embryo development. Maternal black rockfish, having over 50 thousand embryos developing within the ovary simultaneously, provided around 40% nutrition throughout oocyte development, while the capillaries around each embryo contributed the rest 60% during pregnancy. Since fertilization, capillaries started to proliferate and developed into a placenta-like structure that covered over half of each embryo. Aimed to characterize the potential mechanism behind, comparative transcriptome analysis of samples collected according to the process of pregnancy. Three important time point in the process, including mature oocyte stage, fertilization and sarcomere period, were chosen for the transcriptome sequencing. Our study identified key pathways and genes involved in the cell cycle as well as DNA replication and repair, cell migration and adhesion, immune, and metabolic functions. Notably, several of the semaphoring gene family members were differently expressed. To confirm the accuracy of these genes, total of 32 sema genes were identified from the whole genome and distinct expression pattern of sema genes was observed in different pregnant stages. Our results revealed a novel insight for further investigating the functions of sema genes in reproduction physiology and embryo processes in ovoviviparous teleost.

Anoikis resistance in mammary epithelial cells is mediated by semaphorin 7a

Semaphorin-7a (SEMA7A), best known as a neuroimmune molecule, plays a diverse role in many cellular processes and pathologies. Here, we show that SEMA7A promotes anoikis resistance in cultured mammary epithelial cells through integrins and activation of pro-survival kinase AKT, which led us to investigate a role for SEMA7A during postpartum mammary gland involution-a normal developmental process where cells die by anoikis. Our results reveal that SEMA7A is expressed on live mammary epithelial cells during involution, that SEMA7A expression is primarily observed in α6-integrin expressing cells, and that luminal progenitor cells, specifically, are decreased in mammary glands of SEMA7A-/- mice during involution. We further identify a SEMA7A-α6/β1-integrin dependent mechanism of mammosphere formation and chemoresistance in mammary epithelial cells and suggest that this mechanism is relevant for recurrence in breast cancer patients.

New Angiogenic Regulators Produced by TAMs: Perspective for Targeting Tumor Angiogenesis

Simple Summary

Since the targeting of a single pro-angiogenic factor fails to improve oncological disease outcome, significant efforts have been made to identify new pro-angiogenic factors that could compensate for the deficiency of current therapy or act independently as single drugs. Our review aims to present the state-of-the art for well-known and recently described factors produced by macrophages that induce and regulate angiogenesis. A number of positive and negative regulators of angiogenesis in the tumor microenvironment are produced by tumor-associated macrophages (TAMs). Accumulating evidence has indicated that, apart from the well-known angiogenic factors, there are plenty of novel angiogenesis-regulating proteins that belong to different classes. We summarize the data regarding the direct or indirect mechanisms of the interaction of these factors with endothelial cells during angiogenesis. We highlight the recent findings that explain the limitations in the efficiency of current anti-angiogenic therapy approaches.

Abstract

Angiogenesis is crucial to the supply of a growing tumor with nutrition and oxygen. Inhibition of angiogenesis is one of the main treatment strategies for colorectal, lung, breast, renal, and other solid cancers. However, currently applied drugs that target VEGF or receptor tyrosine kinases have limited efficiency, which raises a question concerning the mechanism of patient resistance to the already developed drugs. Tumor-associated macrophages (TAMs) were identified in the animal tumor models as a key inducer of the angiogenic switch. TAMs represent a potent source not only for VEGF, but also for a number of other pro-angiogenic factors. Our review provides information about the activity of secreted regulators of angiogenesis produced by TAMs. They include members of SEMA and S100A families, chitinase-like proteins, osteopontin, and SPARC. The COX-2, Tie2, and other factors that control the pro-angiogenic activity of TAMs are also discussed. We highlight how these recent findings explain the limitations in the efficiency of current anti-angiogenic therapy. Additionally, we describe genetic and posttranscriptional mechanisms that control the expression of factors regulating angiogenesis. Finally, we present prospects for the complex targeting of the pro-angiogenic activity of TAMs.

The involvement of semaphorin 7A in tumorigenic and immunoinflammatory regulation

Semaphorins, a large group of highly conserved proteins, consist of eight subfamilies that are widely expressed in vertebrates, invertebrates, and viruses and exist in membrane-bound or secreted forms. First described as axon guidance cues during neurogenesis, semaphorins also perform physiological functions in other organ systems, such as bone homeostasis, immune response, and tumor progression. Semaphorin 7A (SEMA7A), also known as CDw108, is an immune semaphorin that modulates diverse immunoinflammatory processes, including immune cell interactions, inflammatory infiltration, and cytokine production. In addition, SEMA7A regulates the proliferation, migration, invasion, lymph formation, and angiogenesis of multiple types of tumor cells, and these effects are mediated by the interaction of SEMA7A with two specific receptors, PLXNC1 and integrins. Thus, SEMA7A is intimately related to the pathogenesis of multiple autoimmune and inflammation-related diseases and tumors. This review focuses on the role of SEMA7A in the pathogenesis of autoimmune disorders, inflammatory diseases, and tumors, as well as the underlying mechanisms. Furthermore, strategies targeting SEMA7A as a potential predictive, diagnostic, and therapeutic agent for these diseases are also addressed.

Hormonal Regulation of Semaphorin 7a in ER+ Breast Cancer Drives Therapeutic Resistance

Approximately 70% of all breast cancers are estrogen receptor-positive (ER⁺ breast cancer), and endocrine therapy has improved survival for patients with ER⁺ breast cancer. However, up to half of these tumors recur within 20 years. Recurrent ER⁺ breast cancers develop resistance to endocrine therapy; thus, novel targets are needed to treat recurrent ER⁺ breast cancer. Here we report that semaphorin 7A (SEMA7A) confers significantly decreased patient survival rates in ER⁺ breast cancer. SEMA7A was hormonally regulated in ER⁺ breast cancer, but its expression did not uniformly decrease with antiestrogen treatments. Additionally, overexpression of SEMA7A in ER⁺ cell lines drove increased in vitro growth in the presence of estrogen deprivation, tamoxifen, and fulvestrant. In vivo, SEMA7A conferred primary tumor resistance to fulvestrant and induced lung metastases. Prosurvival signaling was identified as a therapeutic vulnerability of ER⁺SEMA7A⁺ tumors. We therefore propose that targeting this pathway with inhibitors of survival signaling such as venetoclax may prove efficacious for treating SEMA7A⁺ tumors. SIGNIFICANCE: SEMA7A predicts for and likely contributes to poor response to standard-of-care therapies, suggesting that patients with SEMA7A⁺ER⁺ tumors may benefit from alternative therapeutic strategies. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/1/187/F1.large.jpg.

A comprehensive review of tumor proliferative and suppressive role of semaphorins and therapeutic approaches

Semaphorins have been traditionally known as axon guidance proteins that negatively regulate axonal growth. However, in the past couple of decades, their versatile role in so many other biological processes has come to prominence as well. One such example is their role in cancer. In this review article, the focus was on the tumor proliferative and tumor suppressive role of all 20 semaphorin family members under the 7 semaphorin classes found in vertebrates and invertebrates as well as the ongoing and emerging therapeutic approaches to combat semaphorin-mediated cancers. Except sema6C, 19 of the 20 non-viral semaphorin family members have been discovered to be associated with cancer in one way or another. Eleven semaphorin family members have been discovered to be tumor proliferative and 8 to be tumor suppressive. Six therapeutic avenues and their safety profiles have been discussed which are currently at use or at the various stages of development. Finally, perspectives on which approach is the best for treating cancers associated with semaphorins have been given.

Semaphorins in health and disease

Cell-cell communication is pivotal to guide embryo development, as well as to maintain adult tissues homeostasis and control immune response. Among extracellular factors responsible for this function, are the Semaphorins, a broad family of around 20 different molecular cues conserved in evolution and widely expressed in all tissues. The signaling cascades initiated by semaphorins depend on a family of conserved receptors, called Plexins, and on several additional molecules found in the receptor complexes. Moreover, multiple intracellular pathways have been described to act downstream of semaphorins, highlighting significant diversity in the signaling cascades controlled by this family. Notably, semaphorin expression is altered in many human diseases, such as immunopathologies, neurodegenerative diseases and cancer. This underscores the importance of semaphorins as regulatory factors in the tissue microenvironment and has prompted growing interest for assessing their potential relevance in medicine. This review article surveys the main contexts in which semaphorins have been found to regulate developing and healthy adult tissues, and the signaling cascades implicated in these functions. Vis a vis, we will highlight the main pathological processes in which semaphorins are thought to have a role thereof.

Macphatics and PoEMs in Postpartum Mammary Development and Tumor Progression

Postpartum mammary gland involution is a mammalian tissue remodeling event that occurs after pregnancy and lactation to return the gland to the pre-pregnant state. This event is characterized by apoptosis and lysosomal-mediated cell death of the majority of the lactational mammary epithelium, followed by remodeling of the extracellular matrix, influx of immune cell populations (in particular, T helper cells, monocytes, and macrophages), and neo-lymphangiogenesis. This postpartum environment has been shown to be promotional for tumor growth and metastases and may partially account for why women diagnosed with breast cancer during the postpartum period or within 5 years of last childbirth have an increased risk of developing metastases when compared to their nulliparous counterparts. The lymphatics and macrophages present during mammary gland involution have been implicated in promoting the observed growth and metastasis. Of importance are the macrophages, which are of the "M2" phenotype and are known to create a pro-tumor microenvironment. In this report, we describe a subset of postpartum macrophages that express lymphatic proteins (PoEMs) and directly interact with lymphatic vessels to form chimeric vessels or "macphatics". Additionally, these PoEMs are very similar to tumor-associated macrophages that also express lymphatic proteins and are present at the sites of lymphatic vessels where tumors escape the tissue and enter the lymphatic vasculature. Further characterizing these PoEMs may offer insight in preventing lymphatic metastasis of breast cancer, as well as provide information for how developmental programming of lymphatic endothelial cells and macrophages can contribute to different disease progression.

Semaphorins in Angiogenesis and Autoimmune Diseases: Therapeutic Targets?

The axonal guidance molecules, semaphorins, have been described to function both physiologically and pathologically outside of the nervous system. In this review, we focus on the vertebrate semaphorins found in classes 3 through 7 and their roles in vascular development and autoimmune diseases. Recent studies indicate that while some of these vertebrate semaphorins promote angiogenesis, others have an angiostatic function. Since some semaphorins are also expressed by different immune cells and are known to modulate immune responses, they have been implicated in autoimmune disorders such as multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus and systemic sclerosis. We conclude this review by addressing strategies targeting semaphorins as potential therapeutic agents for angiogenesis and autoimmune diseases.

Postpartum breast cancer progression is driven by semaphorin 7a-mediated invasion and survival

Young women diagnosed with breast cancer (BC) have poor prognosis due to increased rates of metastasis. In addition, women diagnosed within 10 years of most recent childbirth are approximately three times more likely to develop metastasis than age- and stage-matched nulliparous women. We define these cases as postpartum BC (PPBC) and propose that the unique biology of the postpartum mammary gland drives tumor progression. Our published results revealed roles for SEMA7A in breast tumor cell growth, motility, invasion, and tumor-associated lymphangiogenesis, all of which are also increased in preclinical models of PPBC. However, whether SEMA7A drives progression in PPBC remains largely unexplored. Our results presented herein show that silencing of SEMA7A decreases tumor growth in a model of PPBC, while overexpression is sufficient to increase growth in nulliparous hosts. Further, we show that SEMA7A promotes multiple known drivers of PPBC progression including tumor-associated COX-2 expression and fibroblast-mediated collagen deposition in the tumor microenvironment. In addition, we show for the first time that SEMA7A-expressing cells deposit fibronectin to promote tumor cell survival. Finally, we show that co-expression of SEMA7A/COX-2/FN predicts for poor prognosis in breast cancer patient cohorts. These studies suggest SEMA7A as a key mediator of BC progression, and that targeting SEMA7A may open avenues for novel therapeutic strategies.

Vitreous Proteomics Provides New Insights into Antivascular Endothelial Growth Factor Therapy for Pathologic Myopia Choroid Neovascularization

This study aimed to investigate the protein expression profile of vitreous humor (VH) from pathologic myopic retinoschisis (PMRS) patients with or without intravitreal antivascular endothelial growth factor (anti-VEGF) therapy. VH samples from PMRS patients were subjected to proteomic analysis. Clinical data, including visual acuity, refractive error, and axial length, were recorded, and the fundus optical coherence tomography was performed. Seven PMRS patients were enrolled: 3 PMRS patients as control group, 3 PMRS patients with coexisting choroidal neovascularization (CNV) who developed retinoschisis aggravation after multiple intravitreal conbercept (IVC) injections, and one PMRS patient with coexisting CNV without leakage CNV (CNV-). A total of 310 differentially expressed proteins were identified in these VH samples. The expression of 28 proteins, related to cellular adhesion, protease inhibitors, proangiogenic factors, and antiangiogenic factors, was significantly downregulated in the IVC-treated eyes than in control- and CNV-eyes. α-smooth muscle actin (α-SMA) expression was significantly upregulated in the IVC-treated eyes. Furthermore, the expression of αA-crystallin and fibrillin-1 was significantly upregulated in both IVC and CNV-eyes than in control eyes. These suggest that multiple IVC injections may increase the VH αSMA concentration, which may contribute to posterior hyaloid membrane or retinal inner limiting membrane contraction. Label-free proteomics is an efficient method to provide further insight into the pathogenesis of vitreoretinal diseases.

Semaphorin 7a participants in pterygium by regulating vascular endothelial growth factor

AIM

To investigate the relationship between semaphorin 7a expression and cell proliferation and migration in pterygium fibroblasts.

METHODS

Twenty-six patients with surgically diagnosed pterygium were enrolled, including 15 cases of primary pterygium and 11 cases of recurrent pterygium. In addition, 12 cases of normal conjunctival tissue were collected. The expression of semaphorin 7a in normal conjunctival tissue, primary pterygium and recurrent pterygium was detected by real-time polymerase chain reaction. Recurrent pterygium fibroblasts were isolated and cultured, and the expression of semaphorin 7a was silenced by small interfering RNA (siRNA) interference technique. Furthermore, the effects of si-semaphorin 7a interference on the mRNA and protein levels of β1-integrin, vascular endothelial growth factor A (VEGFA) and vascular endothelial growth factor receptor (VEGFR), and on fibroblast proliferation were analyzed. Transwell assay was used to detect the effect of semaphorin 7a interference on fibroblast migration.

RESULTS

Semaphorin 7a was highly expressed in the primary pterygium and recurrent pterygium samples than that of the normal conjunctival tissue. Compared with the primary pterygium, the expression of semaphoring 7a in the recurrent pterygium samples was significantly increased (P<0.05). The mRNA and protein expression levels of β1-integrin, VEGFA and VEGFR were decreased after si-semaphorin 7a transfection, and as well as the cell proliferation and migration.

CONCLUSION

Semaphorin 7a might play important roles in the pathogenesis of pterygium by affecting the expression of β1-integrin, VEGFA and VEGFR.

Studies of postpartum mammary gland involution reveal novel pro-metastatic mechanisms

Postpartum involution is the process by which the lactating mammary gland returns to the pre-pregnant state after weaning. Expression of tumor-promotional collagen, upregulation of matrix metalloproteinases, infiltration of M2 macrophages, and remodeling of blood and lymphatic vasculature are all characteristics shared by the involuting mammary gland and breast tumor microenvironment. The tumor promotional nature of the involuting mammary gland is perhaps best evidenced by cases of postpartum breast cancer (PPBC), or those cases diagnosed within 10 years of most recent childbirth. Women with PPBC experience more aggressive disease and higher risk of metastasis than nulliparous patients and those diagnosed outside the postpartum window. Semaphorin 7a (SEMA7A), cyclooxygenase-2 (COX-2), and collagen are all expressed in the involuting mammary gland and, together, predict for decreased metastasis free survival in breast cancer. Studies investigating the role of these proteins in involution have been important for understanding their contributions to PPBC. Postpartum involution thus represents a valuable model for the identification of novel molecular drivers of PPBC and classical cancer hallmarks. In this review, we will highlight the similarities between involution and cancer in the mammary gland, and further define the contribution of SEMA7A/COX-2/collagen interplay to postpartum involution and breast tumor progression and metastasis.

Semaphorin Signaling in Cancer-Associated Inflammation

The inflammatory and immune response elicited by the growth of cancer cells is a major element conditioning the tumor microenvironment, impinging on disease progression and patients’ prognosis. Semaphorin receptors are widely expressed in inflammatory cells, and their ligands are provided by tumor cells, featuring an intense signaling cross-talk at local and systemic levels. Moreover, diverse semaphorins control both cells of the innate and the antigen-specific immunity. Notably, semaphorin signals acting as inhibitors of anti-cancer immune response are often dysregulated in human tumors, and may represent potential therapeutic targets. In this mini-review, we provide a survey of the best known semaphorin regulators of inflammatory and immune cells, and discuss their functional impact in the tumor microenvironment.

Semaphorin 7A promotes EGFR-TKI resistance in EGFR mutant lung adenocarcinoma cells

Although responses to EGFR tyrosine kinase inhibitors (EGFR-TKIs) are initially positive, 30%-40% of patients with EGFR-mutant tumors do not respond well to EGFR-TKIs, and most lung cancer patients harboring EGFR mutations experience relapse with resistance. Therefore, it is necessary to identify not only the mechanisms underlying EGFR-TKI resistance, but also potentially novel therapeutic targets and/or predictive biomarkers for EGFR-mutant lung adenocarcinoma. We found that the GPI-anchored protein semaphorin 7A (SEMA7A) is highly induced by the EGFR pathway, via mTOR signaling, and that expression levels of SEMA7A in human lung adenocarcinoma specimens were correlated with mTOR activation. Investigations using cell culture and animal models demonstrated that loss or overexpression of SEMA7A made cells less or more resistant to EGFR-TKIs, respectively. The resistance was due to the inhibition of apoptosis by aberrant activation of ERK. The ERK signal was suppressed by knockdown of integrin β1 (ITGB1). Furthermore, in patients with EGFR mutant tumors, higher SEMA7A expression in clinical samples predicted poorer response to EGFR-TKI treatment. Collectively, these data show that the SEMA7A-ITGB1 axis plays pivotal roles in EGFR-TKI resistance mediated by ERK activation and apoptosis inhibition. Moreover, our results reveal the potential utility of SEMA7A not only as a predictive biomarker, but also as a potentially novel therapeutic target in EGFR-mutant lung adenocarcinoma.

Semaphorin 7A Promotes VEGFA/VEGFR2-Mediated Angiogenesis and Intraplaque Neovascularization in ApoE-/- Mice

Excessive neovascularization of atherosclerotic lesions increases plaque vulnerability and the susceptibility to rupture. Semaphorin 7A (Sema7A), a semaphorin family member, was recently reported to promote atherosclerotic plaque formation by mediating d-flow-induced endothelial phenotypic change and leukocyte adhesion. To extend our understanding of the proatherogenic role of Sema7A, we investigated the role of endothelial Sema7A in angiogenesis and atherosclerotic neovascularization. Sema7A overexpression in human umbilical vein endothelial cells (HUVECs) significantly upregulated VEGFA/VEGFR2 and promoted cell migration and angiogenesis. This enhancing effect was eliminated by the blockage of Sema7A receptor, β1 integrin. Inhibition of FAK or ERK1/2 downstream of β1 integrin signaling significantly inhibited cell migration and angiogenesis via ROCK (Rho-associated coiled forming protein kinase) and MYPT (myosin phosphatase targeting subunit), which are responsible for actin polymerization. Consistently, in vivo studies showed a remarkable reduction in VEGFA/VEGFR2 expression and neovascularization in the atherosclerotic plaques of Sema7A^-/-ApoE^-/- mice compared with Sema7A^+/+ApoE^-/- littermates. Supportively, Sema7A deficiency reduced the accumulation of T cells, macrophages, and dendritic cells, and enhanced plaque stability in ApoE^-/- mice. Together, our findings show that Sema7A promotes VEGFA/VEGFR2-mediated neovascularization in a β1 integrin-dependent manner, supporting a crucial role of Sema7A in the progression of human atherosclerosis.

Semaphorin 7A Promotes Macrophage-Mediated Lymphatic Remodeling during Postpartum Mammary Gland Involution and in Breast Cancer

Postpartum mammary gland involution is a tissue remodeling event that occurs in all mammals in the absence of nursing or after weaning to return the gland to the pre-pregnant state. The tissue microenvironment created by involution has proven to be tumor promotional. Here we report that the GPI-linked protein semaphorin 7A (SEMA7A) is expressed on mammary epithelial cells during involution and use preclinical models to demonstrate that tumors induced during involution express high levels of SEMA7A. Overexpression of SEMA7A promoted the presence of myeloid-derived podoplanin (PDPN)-expressing cells in the tumor microenvironment and during involution. SEMA7A drove the expression of PDPN in macrophages, which led to integrin- and PDPN-dependent motility and adherence to lymphatic endothelial cells to promote lymphangiogenesis. In support of this mechanism, mammary tissue from SEMA7A-knockout mice exhibited decreased myeloid-derived PDPN-expressing cells, PDPN-expressing endothelial cells, and lymphatic vessel density. Furthermore, coexpression of SEMA7A, PDPN, and macrophage marker CD68 predicted for decreased distant metastasis-free survival in a cohort of over 600 cases of breast cancer as well as in ovarian, lung, and gastric cancers. Together, our results indicate that SEMA7A may orchestrate macrophage-mediated lymphatic vessel remodeling, which in turn drives metastasis in breast cancer.Signficance: SEMA7A, which is expressed on mammary cells during glandular involution, alters macrophage biology and lymphangiogenesis to drive breast cancer metastasis. Cancer Res; 78(22); 6473-85. ©2018 AACR.

Semaphorins and Their Receptors: From Axonal Guidance to Atherosclerosis

Semaphorins are a large family of secreted, transmembrane, or GPI-anchored proteins initially identified as axon guidance cues signaling through their receptors, neuropilins, and plexins. Emerging evidence suggests that beyond the guidance, they also function in a broad spectrum of pathophysiological conditions, including atherosclerosis, a vascular inflammatory disease. Particular semaphorin members have been demonstrated to participate in atherosclerosis via eliciting endothelial dysfunction, leukocyte infiltration, monocyte-macrophage retention, platelet hyperreactivity, and neovascularization. In this review, we focus on the role of those semaphorin family members in the development of atherosclerosis and highlight the mechanistic relevance of semaphorins to atherogenesis.

Impact of semaphorin expression on prognostic characteristics in breast cancer

Breast cancer is one of the major causes of cancer-related deaths among women worldwide. Aberrant regulation of various growth factors, cytokines, and other proteins and their receptors in cancer cells drives the activation of various oncogenic signaling pathways that lead to cancer progression. Semaphorins are a class of proteins which are differentially expressed in various types of cancer including breast cancer. Earlier, these proteins were known to have a major function in the nerve cell adhesion, migration, and development of the central nervous system. However, their role in the regulation of several aspects of tumor progression has eventually emerged. There are over 30 genes encoding the semaphorins, which are divided into eight subclasses. It has been reported that some members of semaphorin classes are antiangiogenic and antimetastatic in nature, whereas others act as proangiogenic and prometastatic genes. Because of their differential expression and role in angiogenesis and metastasis, semaphorins emerged as one of the important prognostic factors for appraising breast cancer progression.

The regulatory network analysis of long noncoding RNAs in human colorectal cancer

Colorectal cancer (CRC) is among one of the most prevalent and lethiferous diseases worldwide. Long noncoding RNAs (lncRNAs) are commonly accepted to function as a key regulatory factor in human cancer, but the potential regulatory mechanisms of CRC-associated lncRNA are largely obscure. Here, we integrated several expression profiles to obtain 55 differentially expressed (DE) lncRNAs. We first detected lncRNA interactions with transcription factors, microRNAs, mRNAs, and RNA-binding proteins to construct a regulatory network and then create functional enrichment analyses for them using bioinformatics approaches. We found the upregulated genes in the regulatory network are enriched in cell cycle and DNA damage response, while the downregulated genes are enriched in cell differentiation, cellular response, and cell signaling. We then employed module-based methods to mine several intriguing modules from the overall network, which helps to classify the functions of genes more specifically. Next, we confirmed the validity of our network by comparisons with a randomized network using computational method. Finally, we attempted to annotate lncRNA functions based on the regulatory network, which indicated its potential application. Our study of the lncRNA regulatory network provided significant clues to unveil lncRNAs potential regulatory mechanisms in CRC and laid a foundation for further experimental investigation.

Proteotranscriptomics Reveal Signaling Networks in the Ovarian Cancer Microenvironment

Ovarian cancer is characterized by early transcoelomic metastatic spread via the peritoneal fluid, where tumor cell spheroids (TU), tumor-associated T cells (TAT), and macrophages (TAM) create a unique microenvironment promoting cancer progression, chemoresistance, and immunosuppression. However, the underlying signaling mechanisms remain largely obscure. To chart these signaling networks, we performed comprehensive proteomic and transcriptomic analyses of TU, TAT, and TAM from ascites of ovarian cancer patients. We identify multiple intercellular signaling pathways driven by protein or lipid mediators that are associated with clinical outcome. Beyond cytokines, chemokines and growth factors, these include proteins of the extracellular matrix, immune checkpoint regulators, complement factors, and a prominent network of axon guidance molecules of the ephrin, semaphorin, and slit families. Intriguingly, both TU and TAM from patients with a predicted short survival selectively produce mediators supporting prometastatic events, including matrix remodeling, stemness, invasion, angiogenesis, and immunosuppression, whereas TAM associated with a longer survival express cytokines linked to effector T-cell chemoattraction and activation. In summary, our study uncovers previously unrecognized signaling networks in the ovarian cancer microenvironment that are of potential clinical relevance.

Suppression of tumor-derived Semaphorin 7A and genetic ablation of host-derived Semaphorin 7A impairs tumor progression in a murine model of advanced breast carcinoma

Solid tumors can generate a plethora of neurogenesis-related molecules that enhance their growth and metastasis. Among them, we have identified axonal guidance molecule Semaphorin 7A (SEMA7A) in breast cancer. The goal of this study was to determine the therapeutic effect of suppressing SEMA7A levels in the 4T1 murine model of advanced breast carcinoma. We used anti-SEMA7A short hairpin RNA (shRNA) to gene silence SEMA7A in 4T1 mammary tumor cells. When implanted into the mammary fat pads of syngeneic mice, SEMA7A shRNA-expressing 4T1 tumors exhibited decreased growth rates, deferred metastasis and reduced mortality. In vitro, SEMA7A shRNA-expressing 4T1 cells had weakened proliferative, migratory and invasive abilities, and decreased levels of mesenchymal factors. Atomic force microscopy studies showed that SEMA7A shRNA-expressing 4T1 cells had an increase in cell stiffness that corresponded with their decreased malignant potential. Genetic ablation of host-derived SEMA7A further enhanced the antitumor effects of SEMA7A shRNA gene silencing in 4T1 cells. Our preclinical findings demonstrate a critical role for SEMA7A in mediating mammary tumor progression.

Semaphorin 7A as a potential immune regulator and promising therapeutic target in rheumatoid arthritis

Background

Semaphorin 7A (Sema7A) is expressed by several different classes of lymphoid and myeloid cells and is a potent immunomodulator. We examined the role of Sema7A in modulating cellular immune responses and to provide experimental data validating the therapeutic potential of Sema7A in rheumatoid arthritis (RA).

Methods

Soluble Sema7A (sSema7A) levels in the serum and synovial fluid from patients with RA or osteoarthritis, as well as cytokine secretions, were analyzed with an enzyme-linked immunosorbent assay. The cell surface levels and transcripts of Sema7A were evaluated in T cells and monocytes from patients with RA. The effect of Sema7A on the functions of primary T cells isolated from the peripheral blood of healthy donors was observed. Detection of the activation of the signal mediator focal adhesion kinase was performed by Western blotting. Shedding of sSema7A was evaluated in monocytes. The introduction of anti-Sema7A antibody to mice with collagen-induced arthritis (CIA) was observed in vivo.

Results

Upregulation of sSema7A levels in both the serum and synovial fluid of patients with RA was correlated with disease activity markers. sSema7A markedly increased Th1/Th17 cytokine secretion and induced evident upregulation of T-bet and retinoic acid receptor-related orphan nuclear receptor γt levels in T cells. Cell surface Sema7A was cleaved by a disintegrin and metalloprotease 17 (ADAM17) in monocytes. Interleukin-6 and tumor necrosis factor-α stimulated ADAM17 secretion in synovial macrophages. Blocking of β1-integrin abrogated the Sema7A-mediated cytokine secretion. Treatment with an anti-Sema7A antibody significantly attenuated CIA.

Conclusions

These findings indicate that Sema7A as a potent activator of T cells and monocytes in the immune response contributes to the inflammation and progression of RA, suggesting its therapeutic potential in the treatment of RA.

The role of the semaphorins in cancer

The semaphorins were initially characterized as axon guidance factors, but have subsequently been implicated also in the regulation of immune responses, angiogenesis, organ formation, and a variety of additional physiological and developmental functions. The semaphorin family contains more then 20 genes divided into 7 subfamilies, all of which contain the signature sema domain. The semaphorins transduce signals by binding to receptors belonging to the neuropilin or plexin families. Additional receptors which form complexes with these primary semaphorin receptors are also frequently involved in semaphorin signaling. Recent evidence suggests that semaphorins also fulfill important roles in the etiology of multiple forms of cancer. Some semaphorins have been found to function as bona-fide tumor suppressors and to inhibit tumor progression by various mechanisms while other semaphorins function as inducers and promoters of tumor progression.

Host miRNA degradation by Herpesvirus saimiri small nuclear RNA requires an unstructured interacting region

Herpesvirus saimiri, an oncogenic herpesvirus, during latency produces seven small nuclear RNAs, called the Herpesvirus saimiri U RNAs (HSUR1-7). HSUR1 mediates degradation of the host microRNA, miR-27, via a process that requires imperfect base-pairing. The decreased levels of miR-27 lead to prolonged T-cell activation and likely contribute to oncogenesis. To gain insight into HSUR1-mediated degradation of miR-27, we probed the in vivo secondary structure of HSUR1 and coupled this with bioinformatic structural analyses. The results suggest that HSUR1 adopts a conformation different than previously believed and that the region complementary to miR-27 lacks stable structure. To determine whether HSUR1 structural flexibility is important for its ability to mediate miR-27 degradation, we performed structurally informative mutagenic analyses of HSUR1. HSUR1 mutants in which the miR-27 binding site sequence is preserved, but sequestered in predicted helices, lose their ability to decrease miR-27 levels. These results indicate that the HSUR1 miR27-binding region must be available in a conformationally flexible segment for noncoding RNA function.

Cortisol regulates the paracrine action of macrophages by inducing vasoactive gene expression in endometrial cells

The human endometrium undergoes inflammation and tissue repair during menstruation. We hypothesized that the local availability of bioactive glucocorticoids plays an important role in immune cell-vascular cell interactions in endometrium during tissue repair at menstruation, acting either directly or indirectly via tissue resident macrophages. We sought to determine whether endometrial macrophages are direct targets for glucocorticoids; whether cortisol-treated macrophages have a paracrine effect on angiogenic gene expression by endometrial endothelial cells; and whether endometrial macrophages express angiogenic factors. Human endometrium (n = 41) was collected with ethical approval and subject consent. Donor peripheral blood monocyte-derived macrophages were treated with estradiol, progesterone, or cortisol. The effect of peripheral blood monocyte-derived macrophage secretory products on the expression of angiogenic RNAs by endothelial cells was examined. Immunofluorescence was used to examine localization in macrophages and other endometrial cell types across the menstrual cycle. Endometrial macrophages express the glucocorticoid receptor. In vitro culture with supernatants from cortisol-treated peripheral blood monocyte-derived macrophages resulted in altered endometrial endothelial cell expression of the angiogenic genes, CXCL2, CXCL8, CTGF, and VEGFC These data highlight the importance of local cortisol in regulating paracrine actions of macrophages in the endometrium. CXCL2 and CXCL8 were detected in endometrial macrophages in situ. The expression of these factors was highest in the endometrium during the menstrual phase, consistent with these factors having a role in endometrial repair. Our data have indicated that activation of macrophages with glucocorticoids might have paracrine effects by increasing angiogenic factor expression by endometrial endothelial cells. This might reflect possible roles for macrophages in endometrial repair of the vascular bed after menstruation.

Semaphorin 7a exerts pleiotropic effects to promote breast tumor progression

Understanding what drives breast tumor progression is of utmost importance for blocking tumor metastasis; we have identified that semaphorin 7a is a potent driver of ductal carcinoma in situ (DCIS) progression. Semaphorin 7a is a GPI membrane anchored protein that promotes attachment and spreading in multiple cell types. Here we show that increased expression of SEMA7A occurs in a large percentage of breast cancers and is associated with decreased overall and distant metastasis free survival. In both in vitro and in vivo models, shRNA mediated silencing of SEMA7A reveals roles for semaphorin 7a in the promotion of DCIS growth, motility, and invasion as well as lymphangiogenesis in the tumor microenvironment. Our studies also uncover a relationship between COX-2 and semaphorin 7a expression and suggest that semaphorin 7a promotes tumor cell invasion on collagen and lymphangiogenesis via activation of β₁-integrin receptor. Our results suggest that semaphorin 7a, may be novel target for blocking breast tumor progression.

CXCR2 Inhibition Combined with Sorafenib Improved Antitumor and Antiangiogenic Response in Preclinical Models of Ovarian Cancer

Antiangiogenic therapy is important for the treatment of gynecological cancer. However, the therapeutic benefit derived from these treatments is transient, predominantly due to the selective activation of compensatory proangiogenic pathways that lead to rapid development of resistance. We aimed to identify and target potential alternative signaling to anti-vascular endothelial growth factor (VEGF) therapy, with a view toward developing a combination of antiangiogenic agents to provide extended therapeutic benefits. We developed a preclinical in vivo phenotypic resistance model of ovarian cancer resistant to antiangiogenic therapy. We measured dynamic changes in secreted chemokines and angiogenic signaling in tumors and plasma in response to anti-VEGF treatment, as tumors advanced from the initial responsive phase to progressive disease. In tumors that progressed following sorafenib treatment, gene and protein expression levels of proangiogenic CXC chemokines and their receptors were significantly elevated, compared with responsive tumors. The chemokine (C-X-C motif) ligand 8 (CXCL8), also known as interleukin-8 (IL-8) increase was time-dependent and coincided with the dynamics of tumor progression. We used SB225002, a pharmacological inhibitor of chemokine (C-X-C motif) receptor 2 (CXCR2), to disrupt the CXC chemokine-mediated functions of ovarian cancer cells in in vitro assays of cell growth inhibition, spheroid formation, and cell migration. The combination of CXCR2 inhibitor with sorafenib led to a synergistic inhibition of cell growth in vitro, and further stabilized tumor progression following sorafenib in vivo. Our results suggest that CXCR2-mediated chemokines may represent an important compensatory pathway that promotes resistance to antiangiogenic therapy in ovarian cancer. Thus, simultaneous blockage of this proangiogenic cytokine pathway using CXCR2 inhibitors and the VEGF receptor (VEGFR) pathway could improve the outcomes of antiangiogenic therapy.

Semaphorin7A Promotion of Tumoral Growth and Metastasis in Human Oral Cancer by Regulation of G1 Cell Cycle and Matrix Metalloproteases: Possible Contribution to Tumoral Angiogenesis

Background

Semaphorins (SEMAs) consist of a large family of secreted and membrane-anchored proteins that are important in neuronal pathfinding and axon guidance in selected areas of the developing nervous system. Of them, SEMA7A has been reported to have a chemotactic activity in neurogenesis and to be an immunomodulator; however, little is known about the relevance of SEMA7A in the behaviors of oral squamous cell carcinoma (OSCC).

Methods

We evaluated SEMA7A expression in OSCC-derived cell lines and primary OSCC samples using quantitative reverse transcriptase-polymerase chain reaction, immunoblotting, and semiquantitative immunohistochemistry (sq-IHC). In addition, SEMA7A knockdown cells (shSEMA7A cells) were used for functional experiments, including cellular proliferation, invasiveness, and migration assays. We also analyzed the clinical correlation between SEMA7A status and clinical behaviors in patients with OSCC.

Results

SEMA7A mRNA and protein were up-regulated significantly (P<0.05) in OSCC-derived cell lines compared with human normal oral keratinocytes. The shSEMA7A cells showed decreased cellular growth by cell-cycle arrest at the G1 phase, resulting from up-regulation of cyclin-dependent kinase inhibitors (p21^Cip1 and p27^Kip1) and down-regulation of cyclins (cyclin D1, cyclin E) and cyclin-dependent kinases (CDK2, CDK4, and CDK6); and decreased invasiveness and migration activities by reduced secretion of matrix metalloproteases (MMPs) (MMP-2, proMMP-2, pro-MMP-9), and expression of membrane type 1- MMP (MT1-MMP). We also found inactivation of the extracellular regulated kinase 1/2 and AKT pathways, an upstream molecule of cell-cycle arrest at the G1 phase, and reduced secretion of MMPs in shSEMA7A cells. sq-IHC showed that SEMA7A expression in the primary OSCCs was significantly (P = 0.001) greater than that in normal counterparts and was correlated with primary tumoral size (P = 0.0254) and regional lymph node metastasis (P = 0.0002).

Conclusion

Our data provide evidence for an essential role of SEMA7A in tumoral growth and metastasis in OSCC and indicated that SEMA7A may play a potential diagnostic/therapeutic target for use in patients with OSCC.

Melanocytes in the skin--comparative whole transcriptome analysis of main skin cell types

Melanocytes possess several functions besides a role in pigment synthesis, but detailed characteristics of the cells are still unclear. We used whole transcriptome sequencing (RNA-Seq) to assess differential gene expression of cultivated normal human melanocytes with respect to keratinocytes, fibroblasts and whole skin. The present results reveal cultivated melanocytes as highly proliferative cells with possible stem cell-like properties. The enhanced readiness to regenerate makes melanocytes the most vulnerable cells in the skin and explains their high risk of developing into malignant melanoma.