Semaphorins in cancer: biological mechanisms and therapeutic approaches

Role of semaphorins, neuropilins and plexins in cancer progression

Progress in understanding nervous system-cancer interconnections has emphasized the functional role of semaphorins (SEMAs) and their receptors, neuropilins (NRPs) and plexins (PLXNs), in cancer progression. SEMAs are a conserved and extensive family of broadly expressed soluble and membrane-associated proteins that were first described as regulators of axon guidance and neural and vascular development. However, recent advances have shown that they can have a dual role in cancer progression, acting either as tumor promoters or suppressors. SEMAs effects result from their interaction with specific co-receptors/receptors NRPs/PLXNs, that have also been described to play a role in cancer progression. They can influence both cancer cells and tumor microenvironment components modulating various aspects of tumorigenesis such as oncogenesis, tumor growth, invasion and metastatic spread or treatment resistance. In this review we focus on the role of these axon guidance signals and their receptors and co-receptors in various aspects of cancer. Furthermore, we also highlight their potential application as novel approaches for cancer treatment in the future.

Neuroscience of cancer: Research progress and emerging of the field

Cancer cells immediately expand and penetrate adjoining tissues, as opposed to metastasis, that is the spread of cancer cells through the circulatory or lymphatic systems to more distant places via the invasion process. We found that a lack of studies discussed tumor development with the nervous system, by the aspects of cancer-tissue invasion (biological) and chemical modulation of growth that cascades by releasing neural-related factors from the nerve endings via chemical substances known as neurotransmitters. In this review, we aimed to carefully demonstrate and describe the cancer invasion and interaction with the nervous system, as well as reveal the research progress and the emerging neuroscience of cancer. An initial set of 160 references underwent systematic review and summarization. Through a meticulous screening process, these data were refined, ultimately leading to the inclusion of 98 studies that adhered to predetermined criteria. The outcomes show that one formidable challenge in the realm of cancer lies in its intrinsic heterogeneity and remarkable capacity for rapid adaptation. Despite advancements in genomics and precision medicine, there is still a need to identify new molecular targets. Considering cancer within its molecular and cellular environment, including neural components, is crucial for addressing this challenge. In conclusion, this review provides good referential data for direct, indirect, biological, and chemical interaction for nerve tissue-tumor interaction, suggesting the establishment of new therapy techniques and mechanisms by controlling and modifying neuron networks that supply signals to tumors.

Semaphorin 3C (Sema3C) reshapes stromal microenvironment to promote hepatocellular carcinoma progression

More than 90% of hepatocellular carcinoma (HCC) cases develop in the presence of fibrosis or cirrhosis, making the tumor microenvironment (TME) of HCC distinctive due to the intricate interplay between cancer-associated fibroblasts (CAFs) and cancer stem cells (CSCs), which collectively regulate HCC progression. However, the mechanisms through which CSCs orchestrate the dynamics of the tumor stroma during HCC development remain elusive. Our study unveils a significant upregulation of Sema3C in fibrotic liver, HCC tissues, peripheral blood of HCC patients, as well as sorafenib-resistant tissues and cells, with its overexpression correlating with the acquisition of stemness properties in HCC. We further identify NRP1 and ITGB1 as pivotal functional receptors of Sema3C, activating downstream AKT/Gli1/c-Myc signaling pathways to bolster HCC self-renewal and tumor initiation. Additionally, HCC cells-derived Sema3C facilitated extracellular matrix (ECM) contraction and collagen deposition in vivo, while also promoting the proliferation and activation of hepatic stellate cells (HSCs). Mechanistically, Sema3C interacted with NRP1 and ITGB1 in HSCs, activating downstream NF-kB signaling, thereby stimulating the release of IL-6 and upregulating HMGCR expression, consequently enhancing cholesterol synthesis in HSCs. Furthermore, CAF-secreted TGF-β1 activates AP1 signaling to augment Sema3C expression in HCC cells, establishing a positive feedback loop that accelerates HCC progression. Notably, blockade of Sema3C effectively inhibits tumor growth and sensitizes HCC cells to sorafenib in vivo. In sum, our findings spotlight Sema3C as a novel biomarker facilitating the crosstalk between CSCs and stroma during hepatocarcinogenesis, thereby offering a promising avenue for enhancing treatment efficacy and overcoming drug resistance in HCC.

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.

Plexin B3 guides axons to cross the midline in vivo

During the development of neural circuits, axons are guided by a variety of molecular cues to navigate through the brain and establish precise connections with correct partners at the right time and place. Many axon guidance cues have been identified and they play pleiotropic roles in not only axon guidance but also axon fasciculation, axon pruning, and synaptogenesis as well as cell migration, angiogenesis, and bone formation. In search of receptors for Sema3E in axon guidance, we unexpectedly found that Plexin B3 is highly expressed in retinal ganglion cells of zebrafish embryos when retinal axons are crossing the midline to form the chiasm. Plexin B3 has been characterized to be related to neurodevelopmental disorders. However, the investigation of its pathological mechanisms is hampered by the lack of appropriate animal model. We provide evidence that Plexin B3 is critical for axon guidance in vivo. Plexin B3 might function as a receptor for Sema3E while Neuropilin1 could be a co-receptor. The intracellular domain of Plexin B3 is required for Semaphorin signaling transduction. Our data suggest that zebrafish could be an ideal animal model for investigating the role and mechanisms of Sema3E and Plexin B3 in vivo.

Analyzing aberrant DNA methylation in colorectal cancer uncovered intangible heterogeneity of gene effects in the survival time of patients

Colorectal cancer (CRC) involves epigenetic alterations. Irregular gene-methylation alteration causes and advances CRC tumor growth. Detecting differentially methylated genes (DMGs) in CRC and patient survival time paves the way to early cancer detection and prognosis. However, CRC data including survival times are heterogeneous. Almost all studies tend to ignore the heterogeneity of DMG effects on survival. To this end, we utilized a sparse estimation method in the finite mixture of accelerated failure time (AFT) regression models to capture such heterogeneity. We analyzed a dataset of CRC and normal colon tissues and identified 3406 DMGs. Analysis of overlapped DMGs with several Gene Expression Omnibus datasets led to 917 hypo- and 654 hyper-methylated DMGs. CRC pathways were revealed via gene ontology enrichment. Hub genes were selected based on Protein-Protein-Interaction network including SEMA7A, GATA4, LHX2, SOST, and CTLA4, regulating the Wnt signaling pathway. The relationship between identified DMGs/hub genes and patient survival time uncovered a two-component mixture of AFT regression model. The genes NMNAT2, ZFP42, NPAS2, MYLK3, NUDT13, KIRREL3, and FKBP6 and hub genes SOST, NFATC1, and TLE4 were associated with survival time in the most aggressive form of the disease that can serve as potential diagnostic targets for early CRC detection.

An Overview of the Molecular Cues and Their Intracellular Signaling Shared by Cancer and the Nervous System: From Neurotransmitters to Synaptic Proteins, Anatomy of an All-Inclusive Cooperation

We propose an overview of the molecular cues and their intracellular signaling involved in the crosstalk between cancer and the nervous system. While "cancer neuroscience" as a field is still in its infancy, the relation between cancer and the nervous system has been known for a long time, and a huge body of experimental data provides evidence that tumor-nervous system connections are widespread. They encompass different mechanisms at different tumor progression steps, are multifaceted, and display some intriguing analogies with the nervous system's physiological processes. Overall, we can say that many of the paradigmatic "hallmarks of cancer" depicted by Weinberg and Hanahan are affected by the nervous system in a variety of manners.

Single-cell RNA-seq reveals the communications between extracellular matrix-related components and Schwann cells contributing to the earlobe keloid formation

Keloid is a major type of skin fibrotic disease, with one prominent feature of extensive accumulation of extracellular matrix (ECM) components, and another feature of pain/itching, which is closely related to the peripheral nervous system (PNS). However, the molecular pathogenesis of these two prominent features still needs to be further explored. In the present study, we performed single-cell RNA sequencing (scRNA-seq) on clinical earlobe keloid samples and adjacent normal skin samples and constructed a keloid atlas of 31,379 cells. All cells were clustered into 13 major cell types using cell-type-specific markers. Among them, fibroblast, vascular endothelial cells, and smooth muscle cells were defined as the ECM-related populations according to their ECM-associated functions. Also, we found that Schwann cells (SCs) were the main neuron cells of PNS in the skin. Interestingly, the cell proportions of ECM-related populations, as well as SC were increased significantly in the earlobe keloid compared to the adjacent normal tissues, suggesting an important role of these cell types in the development of the earlobe keloid. Comprehensive cell-cell interaction analysis at the single-cell level revealed a strong interaction between SC and ECM-related subgroups which might be mediated by SEMA3C signaling pathways and MK/PTN gene family, which are found to be mainly involved in promoting cell proliferation and migration. Moreover, further exploration of the interactions of ECM-related populations and SC in different keloids, including earlobe keloid, back keloid, and chest keloid revealed an increasing amount of TGFβ-TGFβ receptor interactions in chest/back keloids as compared to earlobe keloid, which suggested the anatomic site-specific pathogenesis in different keloids. Altogether, these findings suggested the interactions between ECM-related populations and SC contributing to the earlobe keloid formation and helped us to better understand the pathogenesis of keloids.

Regulation of Semaphorin3A in the process of cutaneous wound healing

Semaphorin 3A (Sema3A) has been recognized as a crucial regulator of morphogenesis and homeostasis over a wide range of organ systems. However, its function in cutaneous wound healing is poorly understood. In our study, we demonstrated that Sema3A adenovirus plasmids transfection limited keratinocyte proliferation and decreased migrative capacity as assessed by in vitro wound healing assay. Sema3A transduction inhibited TGF-β1-mediated keratinocyte migration and EMT process. Besides, we applied mice with K14-Cre-mediated deletion of Sema3A and found that Sema3A depletion postponed wound closure with decreased re-epithelialization and matrix growth. Contrary to the results obtained with full-length Sema3A plasmids transfection, increased keratinocyte migration with recombinant Sema3A proteins resulted in quicker closure of the wounding area after a scratch. Further, exogenously applied recombinant Sema3A worked with EGF to maintain the activation of EGFR by interacting with NRP1 and thereby regulated the internalization of the EGFR-NRP1 complex. Taken together, these results indicated a paradoxical role of autonomous and non-autonomous Sema3A expression during wound healing. Combined administration of recombinant EGF and Sema3A proteins could accelerate the process of wound repair, thus providing promising treatment prospects in the future.

The Sympathetic Nervous System Contributes to the Establishment of Pre-Metastatic Pulmonary Microenvironments

Emerging evidence suggests that neural activity contributes to tumor initiation and its acquisition of metastatic properties. More specifically, it has been reported that the sympathetic nervous system regulates tumor angiogenesis, tumor growth, and metastasis. The function of the sympathetic nervous system in primary tumors has been gradually elucidated. However, its functions in pre-metastatic environments and/or the preparation of metastatic environments far from the primary sites are still unknown. To investigate the role of the sympathetic nervous system in pre-metastatic environments, we performed chemical sympathectomy using 6-OHDA in mice and observed a decrease in lung metastasis by attenuating the recruitment of myeloid-derived suppressor cells. Furthermore, we note that neuro-immune cell interactions could be observed in tumor-bearing mouse lungs in conjunction with the decreased expression of Sema3A. These data indicate that the sympathetic nervous system contributes to the preparation of pre-metastatic microenvironments in the lungs, which are mediated by neuro-immune cell interactions.

Sema3d Restrained Hepatocellular Carcinoma Progression Through Inactivating Pi3k/Akt Signaling via Interaction With FLNA

Hepatocellular carcinoma (HCC) is one of the most lethal malignant tumors worldwide due to the high incidence rate of metastasis and recurrence. Semaphorin 3d (Sema3d) has been shown to play a critical role in vascular development during early embryogenesis and several forms of cancer progression via regulating cell migration. However, the function of Sema3d in hepatocellular carcinoma (HCC) remains elusive. This study aimed to explore the function and mechanisms of Sema3d in HCC. In our study, Sema3d expression was significantly downregulated in HCC tissues and cell lines. Downregulated Sema3d was closely correlated with aggressive clinicopathological features and poor clinical outcomes in HCC patients. Moreover, overexpression of Sema3d in HCCLM3 cells was significantly inhibited and knockdown of Sema3d in PLC/PRF/5 cells promoted proliferation, migration, invasion, and epithelial–mesenchymal transition (EMT) of HCC cells in vitro and tumor growth, EMT, and metastasis in vivo. Furthermore, the RNA sequencing and gene set enrichment analysis (GSEA) indicated that these phenotypic and functional changes in Sema3d-interfered HCC cells were mediated by the Pi3k/Akt signaling pathway, and co-IP–combined mass spectrometry indicated Sema3d might interact with FLNA. Finally, we proved that Sema3d exerted its tumor-restraining effect by interacting with FLNA to inactivate the Pi3k/Akt signaling pathway and remodel the cytoskeleton. Our data showed that Sema3d restrained hepatocellular carcinoma proliferation, invasion, and metastasis through inactivating Pi3k/Akt via interaction with FLNA, which may serve as a novel prognostic predictor and a potential therapeutic target for HCC patients.

The Hippo pathway mediates Semaphorin signaling

Semaphorins were originally identified as axonal guidance molecules, but they also control processes such as vascular development and tumorigenesis. The downstream signaling cascades of Semaphorins in these biological processes remain unclear. Here, we show that the class 3 Semaphorins (SEMA3s) activate the Hippo pathway to attenuate tissue growth, angiogenesis, and tumorigenesis. SEMA3B restoration in lung cancer cells with SEMA3B loss of heterozygosity suppresses cancer cell growth via activating the core Hippo kinases LATS1/2 (large tumor suppressor kinase 1/2). Furthermore, SEMA3 also acts through LATS1/2 to inhibit angiogenesis. We identified p190RhoGAPs as essential partners of the SEMA3A receptor PlexinA in Hippo regulation. Upon SEMA3 treatment, PlexinA interacts with the pseudo-guanosine triphosphatase (GTPase) domain of p190RhoGAP and simultaneously recruits RND GTPases to activate p190RhoGAP, which then stimulates LATS1/2. Disease-associated etiological factors, such as genetic lesions and oscillatory shear, diminish Hippo pathway regulation by SEMA3. Our study thus discovers a critical role of Hippo signaling in mediating SEMA3 physiological function.

Interactions between semaphorins and plexin-neuropilin receptor complexes in the membranes of live cells

Signaling of semaphorin ligands via their plexin-neuropilin receptors is involved in tissue patterning in the developing embryo. These proteins play roles in cell migration and adhesion but are also important in disease etiology, including in cancer angiogenesis and metastasis. While some structures of the soluble domains of these receptors have been determined, the conformations of the full-length receptor complexes are just beginning to be elucidated, especially within the context of the plasma membrane. Pulsed-interleaved excitation fluorescence cross-correlation spectroscopy allows direct insight into the formation of protein-protein interactions in the membranes of live cells. Here, we investigated the homodimerization of neuropilin-1 (Nrp1), plexin A2, plexin A4, and plexin D1 using pulsed-interleaved excitation fluorescence cross-correlation spectroscopy. Consistent with previous studies, we found that Nrp1, plexin A2, and plexin A4 are present as dimers in the absence of exogenous ligand. Plexin D1, on the other hand, was monomeric under similar conditions, which had not been previously reported. We also found that plexin A2 and A4 assemble into a heteromeric complex. Stimulation with semaphorin 3A or semaphorin 3C neither disrupts nor enhances the dimerization of the receptors when expressed alone, suggesting that activation involves a conformational change rather than a shift in the monomer-dimer equilibrium. However, upon stimulation with semaphorin 3C, plexin D1 and Nrp1 form a heteromeric complex. This analysis of interactions provides a complementary approach to the existing structural and biochemical data that will aid in the development of new therapeutic strategies to target these receptors in cancer.

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.

Role of the nervous system in cancers: a review

Nerves are important pathological elements of the microenvironment of tumors, including those in pancreatic, colon and rectal, prostate, head and neck, and breast cancers. Recent studies have associated perineural invasion with tumor progression and poor outcomes. In turn, tumors drive the reprogramming of neurons to recruit new nerve fibers. Therefore, the crosstalk between nerves and tumors is the hot topic and trend in current cancer investigations. Herein, we reviewed recent studies presenting direct supporting evidences for a better understanding of nerve-tumor interactions.

Semaphorin Regulation by the Chromatin Remodeler CHD7: An Emerging Genetic Interaction Shaping Neural Cells and Neural Crest in Development and Cancer

CHD7 is a chromatin remodeler protein that controls gene expression via the formation of multi-protein complexes with specific transcription factors. During development, CHD7 controls several differentiation programs, mainly by acting on neural progenitors and neural crest (NC) cells. Thus, its roles range from the central nervous system to the peripheral nervous system and the organs colonized by NC cells, including the heart. Accordingly, mutated CHD7 is linked to CHARGE syndrome, which is characterized by several neuronal dysfunctions and by malformations of NC-derived/populated organs. Altered CHD7 has also been associated with different neoplastic transformations. Interestingly, recent evidence revealed that semaphorins, a class of molecules involved in developmental and pathological processes similar to those controlled by CHD7, are regulated by CHD7 in a context-specific manner. In this article, we will review the recent insights that support the existence of genetic interactions between these pathways, both during developmental processes and cancer progression.

Plexin-B3 Regulates Cellular Motility, Invasiveness, and Metastasis in Pancreatic Cancer

The Plexins family of proteins are well-characterized transmembrane receptors of semaphorins, axon guidance cue molecules, that mediate the cell attraction or repelling effects for such cues. Plexins and their ligands are involved in numerous cellular activities, such as motility, invasion, and adhesion to the basement membrane. The detachment of cells and the gain in motility and invasion are hallmarks of the cancer metastasis cascade, thus generating interest in exploring the role of plexins in cancer metastasis. Semaphorin-plexin complexes can act as tumor promoters or suppressors, depending upon the cancer type, and are under investigation for therapeutic purposes. Our group has identified Semaphorin-5A (SEMA5A)/Plexin-B3 as an attractive targetable complex for pancreatic cancer (PC) metastasis. However, our understanding of the Plexin-B3 function and pathological expression in PC is limited, and our present study delineates the role of Plexin-B3 in PC malignancy. We examined the pathological expression of Plexin-B3 in PC tumors and metastasis using a human tissue microarray, disease progression model of PDX-Cre-Kras^(G12D) (KC) mice, and different metastatic sites obtained from the Kras^G12D; Trp53^R172H; Pdx1-Cre (KPC) mice model. We observed a higher Plexin-B3 expression in PC tumor cores than the normal pancreas, and different metastatic sites were positive for Plexin-B3 expression. However, in the KC mice model, the Plexin-B3 expression increased initially and then decreased with the disease progression. Next, to evaluate the functional role of Plexin-B3, we utilized T3M-4- and CD18/HPAF-Control and -Plexin B3 knockdown cells for different in vivo and in vitro studies. The knockdown of Plexin-B3 enhanced the in vitro cellular migration, invasiveness, and impaired colony formation in three-dimensional culture, along with an increase in cellular spread and remodeling of the actin filaments. We also observed a higher metastasis in nude mice injected with T3M-4- and CD18/HPAF-shPlexin-B3 cells compared to their respective control cells. Furthermore, we observed a lower number of proliferating Ki-67-positive cells and higher ALDH1-A1-positive cells in the tumors formed by Plexin-B3 knockdown cells compared to tumors formed by the control cells. Together, our data suggest that the loss of Plexin-B3 is associated with the interference of cell division machinery and the induction of stem cell-like characteristics in PC cells.

High SEMA4C expression promotes the epithelial-mesenchymal transition and predicts poor prognosis in colorectal carcinoma

Semaphorin 4C (SEMA4C), is an important regulator of axonal guidance and aggravates tumor development. However, the roles and prognostic value of SEMA4C in colorectal cancer (CRC) remain unclear. Here, bioinformatics analyses of transcriptome data from multiple CRC patient datasets and immunohistochemical staining of a CRC tissue microarray (TMA) (n=83) showed that SEMA4C mRNA and protein expression were higher in CRC tissues than normal colorectal tissues. SEMA4C mRNA and protein expression correlated with pathologic stage and metastasis in CRC patients. Higher SEMA4C expression was associated with shorter overall survival, consensus molecular subtype 4 (CMS4), and DNA hypomethylation of SEMA4C in CRC patients. Multivariate Cox regression analyses revealed that SEMA4C expression was an independent prognostic predictor in CRC patients. Gene set expression analysis (GSEA) illustrated that SEMA4C expression had remarkable correlations with epithelial-mesenchymal transition (EMT) as well as hedgehog, Wnt/β-catenin, TGF-β, and Notch signaling pathways. Receiver operating characteristic (ROC) curve analysis demonstrated that SEMA4C expression accurately distinguished between the CMS4 and CMS1-3 subtypes of CRC patients. By inhibiting EMT, SEMA4C silencing reduced in vitro proliferation, migration, and invasion by CRC cells. These findings suggest that SEMA4C is a CMS4-associated gene that enhances CRC progression by inducing EMT.

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.

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.

Knocking Out SST Gene of BGC823 Gastric Cancer Cell by CRISPR/Cas9 Enhances Migration, Invasion and Expression of SEMA5A and KLF2

Background

The impact and potential molecular mechanisms of SST in the occurrence and development of GC have not been determined.

Materials and Methods

Two pairs of sgRNA and reporter were designed according to targeting sequence of SST gene for double-nicking. Plasmids were transfected into 293T for selecting sgRNA with higher cutting efficiency. The subline which has knocked-out SST gene were selected by FACS and verified by sequencing and expression level. Moreover, the migration and invasion ability was evaluated by wound healing and transwell after knocking out SST. Besides, the protein expression of SEMA5A and KLF2 were observed by Western blotting and LSCM. Last, we detected the expression levels of SST, SEMA5A, and KLF2 in GC tissues by Western blotting.

Results

The results revealed that the new subline 1E9, which had knocked out SST gene, was established by CRISPR/Cas9. In addition, the knockout of SST in GC cells markedly increased migration and invasion ability. The results also demonstrated that the knockout of SST increased the expression of SEMA5A and KLF2. The expression level of SST was decreased in GC tissues, and its decrease was associated with overexpression of SEMA5A and KLF2.

Conclusion

SST plays an inhibitory role in the migration and invasion of GC cell BGC823. The protein expression levels of SEMA5A and KLF2 were enhanced in GC cells and tissues lacking SST expression.

High-Expression of Neuropilin 1 Correlates to Estrogen-Induced Epithelial-Mesenchymal Transition of Endometrial Cells in Adenomyosis

Epithelial-mesenchymal transition (EMT) induced by estrogen contributes to the development of adenomyosis. However, the exact underlying mechanism remains mostly obscure. We hypothesized that a transmembrane glycoprotein neuropilin 1 (NRP1) was critical in the EMT induced by estrogen, accelerating the development of adenomyosis. We firstly investigated the expression pattern of NRP1 in endometrium samples from women with adenomyosis. We found that NRP1 expression was significantly increased in the endometrium of uterine adenomyosis, especially in the ectopic endometrium. To determine the role of NRP1 in the EMT in endometrial cells, we used an NRP1 overexpression retrovirus to up-regulate the NPR1 expression in human endometrial cells (HEC-1-A). Endometrial cells infected with NRP1 retroviruses showed a high expression of NRP1 and exerted a mesenchymal phenotype, characterized by down-regulation of E-cadherin and Occludin, up-regulation of α-SMA and N-cadherin, and enhanced migration. Then, we found that 17β-estradiol (E2) up-regulated the expression of NRP1 in endometrial cells in a dose-dependent manner, which was eliminated by raloxifene, a selective estrogen receptor inhibitor. Importantly, NRP1 shRNA significantly suppressed the EMT induced by E2 in endometrial cells. And NRP1 shRNA significantly inhibited the phosphorylation of Smad3 and restored the expressions of Slug and Snail1 mRNA. Collectively, these data highlight the possible role of NRP1 in the EMT in the development of adenomyosis and provide a potential therapeutic target for adenomyosis patients.

SEMA3C Promotes Cervical Cancer Growth and Is Associated With Poor Prognosis

Introduction: Aberrant activation of Semaphorin3C(SEMA3C) is widespread in human cancers. We aimed to analyze SEMA3C expression in cervical cancer and investigate the role of SEMA3C in cervical cancer and its underlying mechanism, which is important for exploring new therapeutic targets and prognostic factors.

Materials and Methods: The expression of SEMA3C was examined in paraffin-embedded cervical cancer specimens. In vivo and in vitro assays were performed to validate the effect of SEMA3C on cervical cancer cell proliferation and p-ERK pathway activation. Gene Set Enrichment Analysis (GSEA) was performed using The Cancer Genome Atlas (TCGA) data set.

Results: SEMA3C expression was associated with poor survival in both the TCGA cohort and our cohort. Silencing of SEMA3C suppressed cervical cancer cell proliferation, colony formation ability, and the activation of the p-ERK signaling pathway in vitro. SEMA3C depletion inhibited tumor growth in vitro. GSEA also showed that the epithelial mesenchymal transition (EMT), TGFβ signaling pathway, angiogenesis, and extracellular matrix (ECM) receptor interactions are associated with a high SEMA3C expression phenotype.

Conclusion: SEMA3C is correlated with poor prognosis of cervical cancer patients and promotes tumor growth via the activation of the p-ERK pathway.

High Expression Levels of Long Noncoding RNA Small Nucleolar RNA Host Gene 18 and Semaphorin 5A Indicate Poor Prognosis in Multiple Myeloma

BACKGROUND

The aim of this study was to detect the expression of long noncoding RNA small nucleolar RNA host gene 18 (SNHG18) andsemaphorin 5A (SEMA5A) genes in multiple myeloma (MM) patients and to explore the correlation of the expression of these genes with the clinical characteristics and prognosis of MM patients.

METHODS

Forty-seven newly diagnosed MM, 18 complete remission MM, 13 refractory/relapse MM, and 22 iron deficiency anemia (serving as control) samples were extracted at the Department of Hematology, Second Affiliated Hospital of Xian Jiaotong University between January 2015 and December 2016. The clinical features of the MM patients are summarized. Real-time quantitative PCR was performed to analyze the relative expression levels of the SNHG18 and SEMA5Agenes. The clinical characteristics and overall survival (OS) of the MM patients were statistically analyzed while measuring different levels of SNHG18 and SEMA5Agene expression. At the same time, the correlation between the expression of SNHG18 and SEMA5A was also analyzed.

RESULTS

The analysis confirmed that SNHG18 and its possible target gene SEMA5A were both highly expressed in newly diagnosed MM patients. After analyzing the clinical significance of SNHG18 and SEMA5A in MM patients, we found that the expression of SNHG18 and SEMA5A was related to the Durie-Salmon (DS), International Staging System (ISS), and Revised International Staging System (R-ISS) classification systems, and the Mayo Clinic Risk Stratification for Multiple Myeloma (mSMART; p < 0.05). Moreover, we observed a significant difference in OS between the SNHG18/SEMA5A high expression group and the low expression group. We found a positive correlation between SNHG18 and SEMA5A expression (r = 0.709, p < 0.01). Surprisingly, the expected median OS times of both the SNHG18 and SEMA5Ahigh expression groups were significantly decreased, which was in contrast to those of both the SNHG18 and SEMA5Alow expression groups and the single-gene high expression group (p < 0.05).

CONCLUSION

High expression of both SNHG18 and SEMA5A is associated with poor prognosis in patients with MM.

Reverse signaling by semaphorin 4C elicits SMAD1/5- and ID1/3-dependent invasive reprogramming in cancer cells

Semaphorins are a family of molecular signals that guide cell migration and are implicated in the regulation of cancer cells. In particular, transmembrane semaphorins are postulated to act as both ligands (“forward” mode) and signaling receptors (“reverse” mode); however, reverse semaphorin signaling in cancer is relatively less understood. Here, we identified a previously unknown function of transmembrane semaphorin 4C (Sema4C), acting in reverse mode, to elicit nonconventional TGF-β/BMP receptor activation and selective SMAD1/5 phosphorylation. Sema4C coimmunoprecipitated with TGFBRII and BMPR1, supporting its role as modifier of this pathway. Sema4C reverse signaling led to the increased abundance of ID1/3 transcriptional factors and to extensive reprogramming of gene expression, which suppressed the typical features of the epithelial-mesenchymal transition in invasive carcinoma cells. This phenotype was nevertheless coupled with burgeoning metastatic behavior in vivo, consistent with evidence that Sema4C expression correlates with metastatic progression in human breast cancers. Thus, Sema4C reverse signaling promoted SMAD1/5- and ID1/3-dependent gene expression reprogramming and phenotypic plasticity in invasive cancer cells.

NR4A3 fusion proteins trigger an axon guidance switch that marks the difference between EWSR1 and TAF15 translocated extraskeletal myxoid chondrosarcomas

Extraskeletal myxoid chondrosarcoma (EMC) is a rare sarcoma histotype with uncertain differentiation. EMC is hallmarked by the rearrangement of the NR4A3 gene, which in most cases fuses with EWSR1 or TAF15. TAF15‐translocated EMC seem to feature a more aggressive course compared to EWSR1‐positive EMCs, but whether the type of NR4A3 chimera impinges upon EMC biology is still largely undefined. To gain insights on this issue, a series of EMC samples (7 EWSR1‐NR4A3 and 5 TAF15‐NR4A3) were transcriptionally profiled. Our study unveiled that the two EMC variants display a distinct transcriptional profile and that the axon guidance pathway is a major discriminant. In particular, class 4–6 semaphorins and axonal guidance cues endowed with pro‐tumorigenic activity were more expressed in TAF15‐NR4A3 tumors; vice versa, class 3 semaphorins, considered to convey growth inhibitory signals, were more abundant in EWSR1‐NR4A3 EMC. Intriguingly, the dichotomy in axon guidance signaling observed in the two tumor variants was recapitulated in in vitro cell models engineered to ectopically express EWSR1‐NR4A3 or TAF15‐NR4A3. Moreover, TAF15‐NR4A3 cells displayed a more pronounced tumorigenic potential, as assessed by anchorage‐independent growth. Overall, our results indicate that the type of NR4A3 chimera dictates an axon guidance switch and impacts on tumor cell biology. These findings may provide a framework for interpretation of the different clinical–pathological features of the two EMC variants and lay down the bases for the development of novel patient stratification criteria and therapeutic approaches. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Semaphorins and Their Receptors in Hematological Malignancies

While semaphorins were initially identified as axonal guidance cues for wiring the neural network, it was then recognized their wide relevance in tissue development and homeostasis. Notably, semaphorin activities were also extensively studied in many types of solid tumors; however, their relevance in hematological malignancies is far from understood. In this mini-review, we surveyed the current knowledge about semaphorins and their receptors in leukemias, lymphomas, and multiple myeloma. Noteworthy, current data support a promoting role for Semaphorin 4D and Neuropilin-1 in these tumors, while Semaphorin 3A seems to consistently act as oncosuppressor in leukemias and multiple myeloma. The expression levels and functional activities of SEMA3B, SEMA3F, and Neuropilin-2 have furthermore been investigated in leukemias and lymphoma cells. Herein, we reviewed the state of the art and highlighted some of the open questions to be addressed in the field.

Semaphorin 3C as a Therapeutic Target in Prostate and Other Cancers

The semaphorins represent a large family of signaling molecules with crucial roles in neuronal and cardiac development. While normal semaphorin function pertains largely to development, their involvement in malignancy is becoming increasingly evident. One member, Semaphorin 3C (SEMA3C), has been shown to drive a number of oncogenic programs, correlate inversely with cancer prognosis, and promote the progression of multiple different cancer types. This report surveys the body of knowledge surrounding SEMA3C as a therapeutic target in cancer. In particular, we summarize SEMA3C's role as an autocrine andromedin in prostate cancer growth and survival and provide an overview of other cancer types that SEMA3C has been implicated in including pancreas, brain, breast, and stomach. We also propose molecular strategies that could potentially be deployed against SEMA3C as anticancer agents such as biologics, small molecules, monoclonal antibodies and antisense oligonucleotides. Finally, we discuss important considerations for the inhibition of SEMA3C as a cancer therapeutic agent.

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.

Neuroimmune Semaphorin 4A in Cancer Angiogenesis and Inflammation: A Promoter or a Suppressor?

Neuroimmune semaphorin 4A (Sema4A), a member of semaphorin family of transmembrane and secreted proteins, is an important regulator of neuronal and immune functions. In the nervous system, Sema4A primarily regulates the functional activity of neurons serving as an axon guidance molecule. In the immune system, Sema4A regulates immune cell activation and function, instructing a fine tuning of the immune response. Recent studies have shown a dysregulation of Sema4A expression in several types of cancer such as hepatocellular carcinoma, colorectal, and breast cancers. Cancers have been associated with abnormal angiogenesis. The function of Sema4A in angiogenesis and cancer is not defined. Recent studies have demonstrated Sema4A expression and function in endothelial cells. However, the results of these studies are controversial as they report either pro- or anti-angiogenic Sema4A effects depending on the experimental settings. In this mini-review, we discuss these findings as well as our data on Sema4A regulation of inflammation and angiogenesis, which both are important pathologic processes underlining tumorigenesis and tumor metastasis. Understanding the role of Sema4A in those processes may guide the development of improved therapeutic treatments for cancer.

Targeting Semaphorin 3C in Prostate Cancer With Small Molecules

Despite the amenability of early-stage prostate cancer to surgery and radiation therapy, locally advanced and metastatic prostate cancer is clinically problematic. Chemical castration is often used as a first-line therapy for advanced disease, but progression to the castration-resistant prostate cancer phase occurs with dependable frequency, largely through mutations to the androgen receptor (AR), aberrant AR signaling, and AR-independent mechanisms, among other causes. Semaphorin 3C (SEMA3C) is a secreted signaling protein that is essential for cardiac and neuronal development and has been shown to be regulated by the AR, to drive epithelial-to-mesenchymal transition and stem features in prostate cells, to activate receptor tyrosine kinases, and to promote cancer progression. Given that SEMA3C is linked to several key aspects of prostate cancer progression, we set out to explore SEMA3C inhibition by small molecules as a prospective cancer therapy. A homology-based SEMA3C protein structure was created, and its interaction with the neuropilin (NRP)-1 receptor was modeled to guide the development of the corresponding disrupting compounds. Experimental screening of 146 in silico‒identified molecules from the National Cancer Institute library led to the discovery of four promising candidates that effectively bind to SEMA3C, inhibit its association with NRP1, and attenuate prostate cancer growth. These findings provide proof of concept for the feasibility of inhibiting SEMA3C with small molecules as a therapeutic approach for prostate cancer.

Semaphorin 3F and Netrin-1: The Novel Function as a Regulator of Tumor Microenvironment

Axon guidance molecules play an important role in regulating proper neuronal networking during neuronal development. They also have non-neuronal properties, which include angiogenesis, inflammation, and tumor development. Semaphorin 3F (SEMA3F), a member of the class 3 semaphorins, was initially identified as an axon guidance factor, that repels axons and collapses growth cones. However, SEMA3F has similar effects on endothelial cells (ECs) and tumor cells. In this review, we discuss the novel molecular mechanisms underlying SEMA3F activity in vascular and tumor biology. Recent evidence suggests that SEMA3F functions as a PI3K-Akt-mTOR inhibitor in mammalian cells, including T cells, ECs, and tumor cells. Therefore, SEMA3F may have broad therapeutic implications. We also discuss the key role of axon guidance molecules as regulators of the tumor microenvironment. Netrin-1, a chemoattractant factor in the neuronal system, promotes tumor progression by enhancing angiogenesis and metastasis. Moreover, our recent studies demonstrate that netrin-1/neogenin interactions augment CD4+ T cell chemokinesis and elicit pro-inflammatory responses, suggesting that netrin-1 plays a key role in modulating the function of a tumor and its surrounding cells in the tumor microenvironment. Overall, this review focuses on SEMA3F and netrin-1 signaling mechanisms to understand the diverse biological functions of axon guidance molecules.

Signature Gene Identification of Cancer Occurrence and Pattern Recognition

To identify signature genes for the pathogenesis of cancer, which provides a theoretical support for prevention and early diagnosis of cancer. The pattern recognition method was used to analyze the genome-wide gene expression data, which was collected from the The Cancer Genome Atlas (TCGA) database. For the transcription of invasive breast carcinoma, lung adenocarcinoma, lung squamous cell carcinoma, colon adenocarcinoma, renal clear-cell carcinoma, thyroid carcinoma, and hepatocellular carcinoma of the seven cancers, the signature genes were selected by means of a combination of statistical methods, such as correlation, t-test, confidence interval, etc. Modeling by artificial neural network model, the accuracy can be as high as 98% for the TCGA data and as high as 92% for the Gene Expression Omnibus (GEO) independent data, the recognition accuracy of stage I is more than 95%, which is higher compared with the previous study. The common genes emerging in five cancers were obtained from the signature genes of seven cancers, PID1, and SPTBN2. At the same time, we obtain three common pathways of cancer by using Kyoto Encyclopedia of Genes and Genomes' pathway analysis. A functional analysis of the pathways shows their close relationship at the level of gene regulation, which indicted that the identified signature genes play an important role in the pathogenesis of cancer and is very important for understanding the pathogenesis of cancer and the early diagnosis.

Semaphorin 3C and Its Receptors in Cancer and Cancer Stem-Like Cells

Neurodevelopmental programs are frequently dysregulated in cancer. Semaphorins are a large family of guidance cues that direct neuronal network formation and are also implicated in cancer. Semaphorins have two kinds of receptors, neuropilins and plexins. Besides their role in development, semaphorin signaling may promote or suppress tumors depending on their context. Sema3C is a secreted semaphorin that plays an important role in the maintenance of cancer stem-like cells, promotes migration and invasion, and may facilitate angiogenesis. Therapeutic strategies that inhibit Sema3C signaling may improve cancer control. This review will summarize the current research on the Sema3C pathway and its potential as a therapeutic target.

Sema4C/PlexinB2 signaling controls breast cancer cell growth, hormonal dependence and tumorigenic potential

Semaphorin 4C (Sema4C) expression in human breast cancers correlates with poor disease outcome. Surprisingly, upon knock-down of Sema4C or its receptor PlexinB2 in diverse mammary carcinoma cells (but not their normal counterparts), we observed dramatic growth inhibition associated with impairment of G2/M phase transition, cytokinesis defects and the onset of cell senescence. Mechanistically, we demonstrated a Sema4C/PlexinB2/LARG-dependent signaling cascade that is required to maintain critical RhoA-GTP levels in cancer cells. Interestingly, we also found that Sema4C upregulation in luminal-type breast cancer cells drives a dramatic phenotypic change, with disassembly of polarity complexes, mitotic spindle misorientation, cell-cell dissociation and increased migration and invasiveness. We found that this signaling cascade is dependent on the PlexinB2 effectors ErbB2 and RhoA-dependent kinases. Moreover, Sema4C-overexpressing luminal breast cancer cells upregulated the transcription factors Snail, Slug and SOX-2, and formed estrogen-independent metastatic tumors in mice. In sum, our data indicate that Sema4C/PlexinB2 signaling is essential for the growth of breast carcinoma cells, featuring a novel potential therapeutic target. In addition, elevated Sema4C expression enables indolent luminal-type tumors to become resistant to estrogen deprivation, invasive and metastatic in vivo, which could account for its association with a subset of human breast cancers with poor prognosis.

Tumor progression: the neuronal input

One of the challenges of cancer is its heterogeneity and rapid capacity to adapt. Notwithstanding significant progress in the last decades in genomics and precision medicine, new molecular targets and therapies appear highly necessary. One way to approach this complex problem is to consider cancer in the context of its cellular and molecular microenvironment, which includes nerves. The peripheral nerves, the topic of this review, modulate the biological behavior of the cancer cells and influence tumor progression, including the events related to the metastatic spread of the disease. This mechanism involves the release of neurotransmitters directly into the microenvironment and the activation of the corresponding membrane receptors. While this fact appears to complicate further the molecular landscape of cancer, the neurotransmitters are highly investigated molecules, and often are already targeted by well-developed drugs, a fact that can help finding new therapies at a fraction of the cost and time needed for new medicines (through the so-called drug repurposing). Moreover, the modulation of tumor progression by neurotransmitters can probably explain the long-recognized effects of psychological factors on the burden of cancer. We begin with an introduction on the tumor-nervous-connections and a description of the perineural invasion and neoneurogenesis, the two most important interaction patterns of cancer and nerves. Next, we discuss the most recent data that unequivocally demonstrate the necessity of the nervous system for tumor onset and growth. We introduce the molecular players of the tumor-nervous-connections by citing the role of three main families: neurotropic factors, axon guidance molecules, and neurotransmitters. Finally, we review the role the most important neurotransmitters in tumor biology and we conclude by analyzing the significance of the presented data for cancer therapy, with all the potential advantages and caveats.

Semaphorin 3A enhances osteogenesis of MG63 cells through interaction with Schwann cells in vitro

Bone remodeling is under the control of various signals and systems in the body, including the nervous system. Semaphorin (Sema) 3A is a chemorepellent protein which regulates bone mass. Schwann cells, having a pivotal role following nerve injury, interact with Sema3A under numerous circumstances. The present study established a co‑culture system of MG63 and Schwann cells to investigate the role of the interaction between Sema3A and Schwann cells in osteogenesis. The results from the alkaline phosphatase assay, calcium nodule staining and the analysis of the osteogenic gene expression revealed that Sema3A inhibits osteogenic differentiation of MG63 cells in single‑cell culture and promotes osteogenic differentiation of MG63 cells in co‑culture with Schwann cells, in a concentration‑dependent manner. These findings suggest that the presence of Schwann cells induces Sema3A‑associated osteogenic differentiation in bone cells, and also reveals the pivotal role of Sema3A as a regulator in the skeletal and nervous systems, thus contributing to a better understanding of the interaction between these systems.

Androgen receptor transcriptionally regulates semaphorin 3C in a GATA2-dependent manner

The androgen receptor (AR) is a member of the nuclear receptor superfamily of transcription factors and is central to prostate cancer (PCa) progression. Ligand-activated AR engages androgen response elements (AREs) at androgen-responsive genes to drive the expression of gene batteries involved in cell proliferation and cell fate. Understanding the transcriptional targets of the AR has become critical in apprehending the mechanisms driving treatment-resistant stages of PCa. Although AR transcription regulation has been extensively studied, the signaling networks downstream of AR are incompletely described. Semaphorin 3C (SEMA3C) is a secreted signaling protein with roles in nervous system and cardiac development but can also drive cellular growth and invasive characteristics in multiple cancers including PCa. Despite numerous findings that implicate SEMA3C in cancer progression, regulatory mechanisms governing its expression remain largely unknown. Here we identify and characterize an androgen response element within the SEMA3C locus. Using the AR-positive LNCaP PCa cell line, we show that SEMA3C expression is driven by AR through this element and that AR-mediated expression of SEMA3C is dependent on the transcription factor GATA2. SEMA3C has been shown to promote cellular growth in certain cell types so implicit to our findings is the discovery of direct regulation of a growth factor by AR. We also show that FOXA1 is a negative regulator of SEMA3C. These findings identify SEMA3C as a novel target of AR, GATA2, and FOXA1 and expand our understanding of semaphorin signaling and cancer biology.

Semaphorins and Their Roles in Airway Biology: Potential as Therapeutic Targets

Semaphorins are a large family of proteins originally identified as axon guidance cues that play a crucial role in neural development. They are also ubiquitously expressed beyond the nervous system and contribute to regulation of essential cell functions, such as cell migration, proliferation, and adhesion. Binding of semaphorins to their receptors, including plexins and neuropilins, triggers diverse signaling pathways, which are involved in the pathogenesis of various diseases, from cancer to autoimmune and allergic disorders. Despite emerging evidence suggestive of nonredundant roles of semaphorins in cellular and molecular mechanisms of the airway biology, their precise expression and function have not been fully addressed. Here, we first provide an overview about the semaphorin family, their receptors, signaling pathways, and their cellular functions. Then, we highlight the novel findings on the role of semaphorins in airway biology under developmental, homeostatic, and pathological conditions. In particular, we discuss the dual roles of semaphorins in respiratory disorders where they can up- or downregulate processes underlying the pathophysiology of the airway diseases. Next, our recent findings on the expression and function of semaphorin 3E in allergic asthma are further emphasized, and its potential mechanism of action in allergic airway inflammation and remodeling is discussed. Finally, we raise some unanswered questions aiming to develop future research directions.

SEMA3C drives cancer growth by transactivating multiple receptor tyrosine kinases via Plexin B1

Growth factor receptor tyrosine kinase (RTK) pathway activation is a key mechanism for mediating cancer growth, survival, and treatment resistance. Cognate ligands play crucial roles in autocrine or paracrine stimulation of these RTK pathways. Here, we show SEMA3C drives activation of multiple RTKs including EGFR, ErbB2, and MET in a cognate ligand-independent manner via Plexin B1. SEMA3C expression levels increase in castration-resistant prostate cancer (CRPC), where it functions to promote cancer cell growth and resistance to androgen receptor pathway inhibition. SEMA3C inhibition delays CRPC and enzalutamide-resistant progression. Plexin B1 sema domain-containing:Fc fusion proteins suppress RTK signaling and cell growth and inhibit CRPC progression of LNCaP xenografts post-castration in vivo SEMA3C inhibition represents a novel therapeutic strategy for treatment of advanced prostate cancer.

Familial Colorectal Cancer Type X (FCCTX) and the correlation with various genes-A systematic review

Familial Colorectal Cancer Type X (FCCTX) is a type of hereditary nonpolyposis colorectal cancer in accordance to Amsterdam criteria-1 for Lynch syndrome, with no related mutation in mismatch repair gene. FCCTX is microsatellite stable and is accounted for 40% of families with Amsterdam criteria-1 with a high age of onset. Thus, the carcinogenesis of FCCTX is different compared to Lynch syndrome. In addition to the microsatellite stability and the presence of less predominant tumors in proximal colon, various clinical features have also been associated with FCCTX in comparison with Lynch syndrome such as no increased risk of extra-colonic cancers, older age of diagnosis and higher adenoma/carcinoma rate. Genetic etiology of this type of cancer which is autosomal dominant is unknown. In this review, we focus on the genes and their variants identified in this type of CRC. In order to find out the correlation between FCCTX and various genes database such as PubMed and PMC, search engine such as Google scholar and portals such as Springer and Elsevier have been searched. Based on our literature search, several studies suggest that FCCTX is a heterogeneous type of disease with different genetic variants. Recent studies describe the correlation between FCCTX and genes such as BRCA2, SEMA4, NTS, RASSF9, GALNT12, KRAS, BRAF, APC, BMPR1A, and RPS20. Considering the fact that BRCA2 has the highest mutation rate (60%) and is one of the most crucial DNA repair genes, it will be considered as a big role player in this type of cancer in comparison with other genes.

Whole-genome and Transcriptome Sequencing of Prostate Cancer Identify New Genetic Alterations Driving Disease Progression

BACKGROUND

Global disparities in prostate cancer (PCa) incidence highlight the urgent need to identify genomic abnormalities in prostate tumors in different ethnic populations including Asian men.

OBJECTIVE

To systematically explore the genomic complexity and define disease-driven genetic alterations in PCa.

DESIGN, SETTING, AND PARTICIPANTS

The study sequenced whole-genome and transcriptome of tumor-benign paired tissues from 65 treatment-naive Chinese PCa patients. Subsequent targeted deep sequencing of 293 PCa-relevant genes was performed in another cohort of 145 prostate tumors.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The genomic alteration landscape in PCa was analyzed using an integrated computational pipeline. Relationships with PCa progression and survival were analyzed using nonparametric test, log-rank, and multivariable Cox regression analyses.

RESULTS AND LIMITATIONS

We demonstrated an association of high frequency of CHD1 deletion with a low rate of TMPRSS2-ERG fusion and relatively high percentage of mutations in androgen receptor upstream activator genes in Chinese patients. We identified five putative clustered deleted tumor suppressor genes and provided experimental and clinical evidence that PCDH9, deleted/loss in approximately 23% of tumors, functions as a novel tumor suppressor gene with prognostic potential in PCa. Furthermore, axon guidance pathway genes were frequently deregulated, including gain/amplification of PLXNA1 gene in approximately 17% of tumors. Functional and clinical data analyses showed that increased expression of PLXNA1 promoted prostate tumor growth and independently predicted prostate tumor biochemical recurrence, metastasis, and poor survival in multi-institutional cohorts of patients with PCa. A limitation of this study is that other genetic alterations were not experimentally investigated.

CONCLUSIONS

There are shared and salient genetic characteristics of PCa in Chinese and Caucasian men. Novel genetic alterations in PCDH9 and PLXNA1 were associated with disease progression.

PATIENT SUMMARY

We reported the first large-scale and comprehensive genomic data of prostate cancer from Asian population. Identification of these genetic alterations may help advance prostate cancer diagnosis, prognosis, and treatment.

Semaphorin 3 C drives epithelial-to-mesenchymal transition, invasiveness, and stem-like characteristics in prostate cells

Prostate cancer (PCa) is among the most commonly-occurring cancers worldwide and a leader in cancer-related deaths. Local non-invasive PCa is highly treatable but limited treatment options exist for those with locally-advanced and metastatic forms of the disease underscoring the need to identify mechanisms mediating PCa progression. The semaphorins are a large grouping of membrane-associated or secreted signalling proteins whose normal roles reside in embryogenesis and neuronal development. In this context, semaphorins help establish chemotactic gradients and direct cell movement. Various semaphorin family members have been found to be up- and down-regulated in a number of cancers. One family member, Semaphorin 3 C (SEMA3C), has been implicated in prostate, breast, ovarian, gastric, lung, and pancreatic cancer as well as glioblastoma. Given SEMA3C's roles in development and its augmented expression in PCa, we hypothesized that SEMA3C promotes epithelial-to-mesenchymal transition (EMT) and stem-like phenotypes in prostate cells. In the present study we show that ectopic expression of SEMA3C in RWPE-1 promotes the upregulation of EMT and stem markers, heightened sphere-formation, and cell plasticity. In addition, we show that SEMA3C promotes migration and invasion in vitro and cell dissemination in vivo.

Tri-methylation of H3K79 is decreased in TGF-β1-induced epithelial-to-mesenchymal transition in lung cancer

BACKGROUND

The epithelial-to-mesenchymal transition (EMT) enables epithelial cancer cells to acquire mesenchymal features and contributes to metastasis and resistance to treatment. This process involves epigenetic reprogramming for gene expression. We explored global histone modifications during TGF-β1-induced EMT in two non-small cell lung cancer (NSCLC) cell lines and tested different epigenetic treatment to modulate or partially reverse EMT.

RESULTS

Loss of classical epithelial markers and gain of mesenchymal markers were verified in A549 and H358 cell lines during TGF-β1-induced EMT. In addition, we noticed increased expression of the axonal guidance protein semaphorin 3C (SEMA3C) and PD-L1 (programmed death-ligand 1) involved in the inhibition of the immune system, suggesting that both SEMA3C and PD-L1 could be the new markers of TGF-β1-induced EMT. H3K79me3 and H2BK120me1 were decreased in A549 and H358 cell lines after a 48-h TGF-β1 treatment, as well as H2BK120ac in A549 cells. However, decreased H3K79me3 was not associated with expression of the histone methyltransferase DOT1L. Furthermore, H3K79me3 was decreased in tumors compared in normal tissues and not associated with cell proliferation. Associations of histone deacetylase inhibitor (SAHA) with DOT1L inhibitors (EPZ5676 or SGC0946) or BET bromodomain inhibitor (PFI-1) were efficient to partially reverse TGF-β1 effects by decreasing expression of PD-L1, SEMA3C, and its receptor neuropilin-2 (NRP2) and by increasing epithelial markers such as E-cadherin.

CONCLUSION

Histone methylation was modified during EMT, and combination of epigenetic compounds with conventional or targeted chemotherapy might contribute to reduce metastasis and to enhance clinical responses.

Stage-specific functions of Semaphorin7A during adult hippocampal neurogenesis rely on distinct receptors

The guidance protein Semaphorin7A (Sema7A) is required for the proper development of the immune and nervous systems. Despite strong expression in the mature brain, the role of Sema7A in the adult remains poorly defined. Here we show that Sema7A utilizes different cell surface receptors to control the proliferation and differentiation of neural progenitors in the adult hippocampal dentate gyrus (DG), one of the select regions of the mature brain where neurogenesis occurs. PlexinC1 is selectively expressed in early neural progenitors in the adult mouse DG and mediates the inhibitory effects of Sema7A on progenitor proliferation. Subsequently, during differentiation of adult-born DG granule cells, Sema7A promotes dendrite growth, complexity and spine development through β1-subunit-containing integrin receptors. Our data identify Sema7A as a key regulator of adult hippocampal neurogenesis, providing an example of how differential receptor usage spatiotemporally controls and diversifies the effects of guidance cues in the adult brain.

The axon guidance molecule semaphorin 3F is a negative regulator of tumor progression and proliferation in ileal neuroendocrine tumors

Gastro-intestinal neuroendocrine tumors (GI-NETs) are rare neoplasms, frequently metastatic, raising difficult clinical and therapeutic challenges due to a poor knowledge of their biology. As neuroendocrine cells express both epithelial and neural cell markers, we studied the possible involvement in GI-NETs of axon guidance molecules, which have been shown to decrease tumor cell proliferation and metastatic dissemination in several tumor types. We focused on the role of Semaphorin 3F (SEMA3F) in ileal NETs, one of the most frequent subtypes of GI-NETs.

SEMA3F expression was detected in normal neuroendocrine cells but was lost in most of human primary tumors and all their metastases. SEMA3F loss of expression was associated with promoter gene methylation. After increasing endogenous SEMA3F levels through stable transfection, enteroendocrine cell lines STC-1 and GluTag showed a reduced proliferation rate in vitro. In two different xenograft mouse models, SEMA3F-overexpressing cells exhibited a reduced ability to form tumors and a hampered liver dissemination potential in vivo. This resulted, at least in part, from the inhibition of mTOR and MAPK signaling pathways.

This study demonstrates an anti-tumoral role of SEMA3F in ileal NETs. We thus suggest that SEMA3F and/or its cellular signaling pathway could represent a target for ileal NET therapy.

Regulation of semaphorin 4D expression and cell proliferation of ovarian cancer by ERalpha and ERbeta

Ovarian cancer is one of the most common malignancies in women. Semaphorin 4D (sema 4D) is involved in the progress of multiple cancers. In the presence of estrogen-like ligands, estrogen receptors (ERα and ERβ) participate in the progress of breast and ovarian cancers by transcriptional regulation. The aim of the study was to investigate the role of sema 4D and elucidate the regulatory pattern of ERα and ERβ on sema 4D expression in ovarian cancers. Sema 4D levels were up-regulated in ovarian cancer SKOV-3 cells. Patients with malignant ovarian cancers had significantly higher sema 4D levels than controls, suggesting an oncogene role of sema 4D in ovarian cancer. ERα expressions were up-regulated in SKOV-3 cells compared with normal ovarian IOSE80 epithelial cells. Conversely, down-regulation of ERβ was observed in SKOV-3 cells. Forced over-expression of ERα and ERβ in SKOV-3 cells was manipulated to establish ERα⁺ and ERβ⁺ SKOV-3 cell lines. Incubation of ERα⁺ SKOV-3 cells with ERs agonist 17β-estradiol (E2) significantly enhanced sema 4D expression and rate of cell proliferation. Incubated with E2, ERβ⁺ SKOV-3 cells showed lower sema 4D expression and cell proliferation. Blocking ERα and ERβ activities with ICI182-780 inhibitor, sema 4D expressions and cell proliferation of ERα⁺ and ERβ⁺ SKOV-3 cells were recovered to control levels. Taken together, the data showed that sema 4D expression was positively correlated with the progress of ovarian cancer. ERα positively regulated sema 4D expression and accelerated cell proliferation. ERβ negatively regulated sema 4D expression and inhibited cell multiplication.

Experimental Approaches for Studying Semaphorin Signals in Tumor Growth and Metastasis in Mouse Models

Tumor growth and metastatic dissemination are complex multistep processes. They clearly depend on the intrinsic behavior of cancer cells, but are remarkably influenced by a variety of stromal cells present in the tumor microenvironment, which include those implicated in tumor angiogenesis, as well as bone marrow-derived cells recruited from the circulation. Moreover, multiple molecular signals exchanged between cancer cells and non-neoplastic stromal cells control tumor growth and metastasis; notably, members of the semaphorin family are emerging players in this scenario.In vivo tumor models represent the best setting for studying metastatic tumor progression, as they allow recapitulating the contribution of multiple cell types and signaling molecules in a complex tissue context, subject to pathophysiological local and systemic responses, such as metabolic changes, hypoxia, necrosis, fibrosis, inflammation, and cytokine release. Here, we describe some experimental approaches based on murine models to study the role of semaphorin signaling in tumor growth and metastatic progression in vivo.

PlexinD1 Is a Novel Transcriptional Target and Effector of Notch Signaling in Cancer Cells

The secreted semaphorin Sema3E controls cell migration and invasiveness in cancer cells. Sema3E-receptor, PlexinD1, is frequently upregulated in melanoma, breast, colon, ovarian and prostate cancers; however, the mechanisms underlying PlexinD1 upregulation and the downstream events elicited in tumor cells are still unclear. Here we show that the canonical RBPjk-dependent Notch signaling cascade controls PlexinD1 expression in primary endothelial and cancer cells. Transcriptional activation was studied by quantitative PCR and promoter activity reporter assays. We found that Notch ligands and constitutively activated intracellular forms of Notch receptors upregulated PlexinD1 expression; conversely RNAi-based knock-down, or pharmacological inhibition of Notch signaling by gamma-secretase inhibitors, downregulated PlexinD1 levels. Notably, both Notch1 and Notch3 expression positively correlates with PlexinD1 levels in prostate cancer, as well as in other tumor types. In prostate cancer cells, Sema3E-PlexinD1 axis was previously reported to regulate migration; however, implicated mechanisms were not elucidated. Here we show that in these cells PlexinD1 activity induces the expression of the transcription factor Slug, downregulates E-cadherin levels and enhances cell migration. Moreover, our mechanistic data identify PlexinD1 as a pivotal mediator of this signaling axis downstream of Notch in prostate cancer cells. In fact, on one hand, PlexinD1 is required to mediate cell migration and E-cadherin regulation elicited by Notch. On the other hand, PlexinD1 upregulation is sufficient to induce prostate cancer cell migration and metastatic potential in mice, leading to functional rescue in the absence of Notch. In sum, our work identifies PlexinD1 as a novel transcriptional target induced by Notch signaling, and reveals its role promoting prostate cancer cell migration and downregulating E-cadherin levels in Slug-dependent manner. Collectively, these findings suggest that Notch-PlexinD1 signaling axis may be targeted to impair prostate cancer cell invasiveness and metastasis.

Enhanced expression of semaphorin 3E is involved in the gastric cancer development

Semaphorins and their receptors are abnormally expressed in various cancers, but little is known about the expression and function of semaphorin 3E (SEMA3E) and its receptor, plexin D1 (PLXND1), in gastric cancer development or metastasis. We evaluated SEMA3E and PLXND1 expression by quantitative RT-PCR in gastric tissues from 62 patients who underwent gastrectomy and analyzed the correlation between their expression and clinicopathological variables. To assess the function of SEMA3E, we generated human gastric cancer cell lines with suppressed or increased SEMA3E expression. The expression level of SEMA3E, but not PLXND1, was correlated with lymph node involvement and metastatic progression in gastric cancer. A significant association was observed between a high level of SEMA3E expression and poor differentiation or poor survival in the intestinal type of gastric cancer. SEMA3E knockdown in gastric cancer cells attenuated cell proliferation and metastatic ability in vitro and in vivo. Moreover, SEMA3E caused cell proliferation and anchorage-independent cell growth in the intestinal type of gastric cancer. These results suggested that SEMA3E is likely to be involved in the development of gastric cancer and might also be a therapeutic target for its treatment.