Transmembrane CEACAM1 affects integrin-dependent signaling and regulates extracellular matrix protein-specific morphology and migration of endothelial cells

The role of carcinoembryonic antigen-related cell adhesion molecule 1 in cancer

The Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1), also known as CD66a, is a member of the immunoglobulin superfamily. CEACAM1 was shown to be a prognostic marker in patients suffering from cancer. In this review, we summarize pre-clinical and clinical evidence linking CEACAM1 to tumorigenicity and cancer progression. Furthermore, we discuss potential CEACAM1-based mechanisms that may affect cancer biology.

CEACAM expression in an in-vitro prostatitis model

Background

Prostatitis is an inflammatory disease of the prostate gland, which affects 2-16% of men worldwide and thought to be a cause for prostate cancer (PCa) development. Carcinoembryogenic antigen-related cell adhesion molecules (CEACAMs) are deregulated in inflammation and in PCa. The role of CEACAMs in prostate inflammation and their possible contribution to the malignant transformation of prostate epithelial cells is still elusive. In this study, we investigated the expression of CEACAMs in an in-vitro prostatitis model and their potential role in malignant transformation of prostate epithelial cells.

Methods

Normal prostate epithelial RWPE-1 cells were treated with pro-inflammatory cytokines to achieve an inflammatory state of the cells. The expression of CEACAMs and their related isoforms were analyzed. Additionally, the expression levels of selected CEACAMs were correlated with the expression of malignancy markers and the migratory properties of the cells.

Results

This study demonstrates that the pro-inflammatory cytokines, tumor necrosis factor alpha (TNFα) and interferon-gamma (IFNγ), induce synergistically an up-regulation of CEACAM1 expression in RWPE-1 cells, specifically favoring the CEACAM1-L isoform. Furthermore, overexpressed CEACAM1-L is associated with the deregulated expression of JAK/STAT, NFκB, and epithelial-mesenchymal transition (EMT) genes, as well as an increased cell migration.

Conclusion

We postulate that CEACAM1 isoform CEACAM1-4L may synergistically contribute to inflammation-induced oncogenesis in the prostate.

CEACAM1 Is a Prognostic Biomarker and Correlated with Immune Cell Infiltration in Clear Cell Renal Cell Carcinoma

Background

CEACAM1 has been shown to be aberrantly expressed in a variety of tumors, and modulation of CEACAM1-related signaling pathways has been suggested as a novel approach for cancer immunotherapy in recent years. However, its role in clear cell renal cell carcinoma (ccRCC) is unclear.

Methods

The relationship between CEACAM1 and ccRCC was demonstrated based on data from TCGA, GEO, and HPA databases. And the relationship between clinicopathological features and CEACAM1 expression was also assessed. Survival curve analysis was performed to analyze the prognostic relationship between CEACAM1 expression and ccRCC. Protein interaction network analysis was used to analyze the relationship between CEACAM1 and microenvironment-related proteins. In addition, the immunomodulatory role of CEACAM1 in ccRCC was assessed by analyzing CEACAM1 and immune cell infiltration.

Results

The expression of CEACAM1 was lower in ccRCC tissues than in adjacent normal tissues, and its expression level was negatively correlated with tumor size status (P < 0.001), metastasis status (P = 0.009), pathological stage (P = 0.002), gender (P < 0.001), histological grade (P < 0.001), and primary therapy outcome (P = 0.045) of ccRCC. Survival curve analysis showed that ccRCC patients with lower CEACAM1 expression exhibited shorter overall survival (P < 0.001), and CEACAM1 interacted with microenvironmental molecules such as fibronectin and integrins. Furthermore, immune infiltration analysis showed that CEACAM1 expression correlated with CD8⁺ and CD4⁺ T cells, macrophage, neutrophil, and dendritic cell infiltration in ccRCC.

Conclusions

CEACAM1 expression correlates with progression, prognosis, and immune cell infiltration in ccRCC patients, and it may be a promising prognostic biomarker and therapeutic target for ccRCC.

Effects of Helicobacter pylori adhesin HopQ binding to CEACAM receptors in the human stomach

Helicobacter pylori has developed several strategies using its diverse virulence factors to trigger and, at the same time, limit the host's inflammatory responses in order to establish a chronic infection in the human stomach. One of the virulence factors that has recently received more attention is a member of the Helicobacter outer membrane protein family, the adhesin HopQ, which binds to the human Carcinoembryonic Antigen-related Cell Adhesion Molecules (CEACAMs) on the host cell surface. The HopQ-CEACAM interaction facilitates the translocation of the cytotoxin-associated gene A (CagA), an important effector protein of H. pylori, into host cells via the Type IV secretion system (T4SS). Both the T4SS itself and CagA are important virulence factors that are linked to many aberrant host signaling cascades. In the last few years, many studies have emphasized the prerequisite role of the HopQ-CEACAM interaction not only for the adhesion of this pathogen to host cells but also for the regulation of cellular processes. This review summarizes recent findings about the structural characteristics of the HopQ-CEACAM complex and the consequences of this interaction in gastric epithelial cells as well as immune cells. Given that the upregulation of CEACAMs is associated with many H. pylori-induced gastric diseases including gastritis and gastric cancer, these data may enable us to better understand the mechanisms of H. pylori's pathogenicity.

Antibody ligation of CEACAM1, CEACAM3, and CEACAM6, differentially enhance the cytokine release of human neutrophils in responses to Candida albicans

Invasive candidiasis is a healthcare-associated fungal infection with a high mortality rate. Neutrophils, the first line of defense during fungal infections, express the immunoregulatory Candida albicans receptors CEACAM1, CEACAM3, and CEACAM6. We analyzed the effects of specific antibodies on C. albicans-induced neutrophil responses. CEACAM6 ligation by 1H7-4B and to some extent CEACAM1 ligation by B3-17, but not CEACAM3 ligation by 308/3-3, resulted in the immediate release of stored CXCL8 and altered transcriptional responses of the C. albicans-stimulated neutrophils. Integrated network analyses and dynamic simulations of signaling cascades predicted alterations in apoptosis and cytokine secretion. We verified that CEACAM6 ligation enhanced Candida-induced neutrophil apoptosis and increased long-term IL-1β/IL-6 release in responses to C. albicans. CEACAM3 ligation, but not CEACAM1 ligation, increased the long-term release of pro-inflammatory IL-1β/IL-6. Taken together, we demonstrated for the first time that ligation of CEACAM receptors differentially affects the regulation of C. albicans-induced immune functions in human neutrophils.

Association of Proteins Modulating Immune Response and Insulin Clearance During Gestation with Antenatal Complications in Patients with Gestational or Type 2 Diabetes Mellitus

Background: The purpose of the study is to establish and quantitatively assess protein markers and their combination in association with insulin uptake that may be have value for early prospective recognition of diabetic fetopathy (DF) as a complication in patients with diabetes mellitus during gestation. Methods: Proteomic surveying and accurate quantitative measurement of selected proteins from plasma samples collected from the patients with gestational diabetes mellitus (GDM) and type 2 diabetes mellitus (T2DM) who gave birth of either healthy or affected by maternal diabetes newborns was performed using mass spectrometry. Results: We determined and quantitatively measured several proteins, including CRP, CEACAM1, CNDP1 and Ig-family that were significantly differed in patients that gave birth of newborns with signs of DF. We found that patients with newborns associated with DF are characterized by significantly decreased CEACAM1 (113.18 ± 16.23 ng/mL and 81.09 ± 10.54 ng/mL in GDM and T2DM, p < 0.005) in contrast to control group (515.6 ± 72.14 ng/mL, p < 0.005). On the contrary, the concentration of CNDP1 was increased in DF-associated groups and attained 49.3 ± 5.18 ng/mL and 37.7 ± 3.34 ng/mL (p < 0.005) in GDM and T2DM groups, respectively. Among other proteins, dramatically decreased concentration of IgG4 and IgA2 subclasses of immunoglobulins were noticed. Conclusion: The combination of the measured markers may assist (AUC = 0.893 (CI 95%, 0.785–0.980) in establishing the clinical finding of the developing DF especially in patients with GDM who are at the highest risk of chronic insulin resistance.

Unaltered Fungal Burden and Lethality in Human CEACAM1-Transgenic Mice During Candida albicans Dissemination and Systemic Infection

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1, CD66a) is a receptor for Candida albicans. It is crucial for the immune response of intestinal epithelial cells to this opportunistic pathogen. Moreover, CEACAM1 is of importance for the mucosal colonization by different bacterial pathogens. We therefore studied the influence of the human CEACAM1 receptor in human CEACAM1-transgenic mice on the C. albicans colonization and infection utilizing a colonization/dissemination and a systemic infection mouse model. Our results showed no alterations in the host response between the transgenic mice and the wild-type littermates to the C. albicans infections. Both mouse strains showed comparable C. albicans colonization and mycobiota, similar fungal burdens in various organs, and a similar survival in the systemic infection model. Interestingly, some of the mice treated with anti-bacterial antibiotics (to prepare them for C. albicans colonization via oral infection) also showed a strong reduction in endogenous fungi instead of the normally observed increase in fungal numbers. This was independent of the expression of human CEACAM1. In the systemic infection model, the human CEACAM1 expression was differentially regulated in the kidneys and livers of Candida-infected transgenic mice. Notably, in the kidneys, a total loss of the largest human CEACAM1 isoform was observed. However, the overwhelming immune response induced in the systemic infection model likely covered any CEACAM1-specific effects in the transgenic animals. In vitro studies using bone marrow-derived neutrophils from both mouse strains also revealed no differences in their reaction to C. albicans. In conclusion, in contrast to bacterial pathogens interacting with CEACAM1 on different mucosal surfaces, the human CEACAM1-transgenic mice did not reveal a role of human CEACAM1 in the in vivo candidiasis models used here. Further studies and different approaches will be needed to reveal a putative role of CEACAM1 in the host response to C. albicans.

Size Matters: The Functional Role of the CEACAM1 Isoform Signature and Its Impact for NK Cell-Mediated Killing in Melanoma

Malignant melanoma is the most aggressive and treatment resistant type of skin cancer. It is characterized by continuously rising incidence and high mortality rate due to its high metastatic potential. Various types of cell adhesion molecules have been implicated in tumor progression in melanoma. One of these, the carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1), is a multi-functional receptor protein potentially expressed in epithelia, endothelia, and leukocytes. CEACAM1 often appears in four isoforms differing in the length of their extracellular and intracellular domains. Both the CEACAM1 expression in general, and the ratio of the expressed CEACAM1 splice variants appear very dynamic. They depend on both the cell activation stage and the cell growth phase. Interestingly, normal melanocytes are negative for CEACAM1, while melanomas often show high expression. As a cell–cell communication molecule, CEACAM1 mediates the direct interaction between tumor and immune cells. In the tumor cell this interaction leads to functional inhibitions, and indirectly to decreased cancer cell immunogenicity by down-regulation of ligands of the NKG2D receptor. On natural killer (NK) cells it inhibits NKG2D-mediated cytolysis and signaling. This review focuses on novel mechanistic insights into CEACAM1 isoforms for NK cell-mediated immune escape mechanisms in melanoma, and their clinical relevance in patients suffering from malignant melanoma.

Mutual Regulation of TLR/NLR and CEACAM1 in the Intestinal Microvasculature: Implications for IBD Pathogenesis and Therapy

BACKGROUND

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) displays multiple activities, among which pathogen binding and angiogenesis are particularly prominent. These same functions are also exerted by Toll- and NOD-like receptors (TLRs and NLRs), which are critical mediators of innate immune responses. We investigated whether a functional inter-relationship exists between CEACAM1 and TLRs and NLRs and its potential impact on induction of intestinal angiogenesis.

METHODS

This hypothesis was tested using human intestinal microvascular endothelial cells, a unique cell population exposed to microbial products under physiological and pathological conditions.

RESULTS

The results show that activation of TLR2/4, TLR4, NOD1, and NOD2 by specific bacterial ligands selectively and differentially upregulates the levels of cellular and soluble CEACAM1 produced by intestinal microvascular endothelial cells. The results also show that CEACAM1 regulates the migration, transmigration, and tube formation of these endothelial cells and mediates vessel sprouting induced by specific TLR and NLR bacterial ligands. Combined, these results demonstrate a close and reciprocal regulatory interaction between CEACAM1 and bacterial products in mediating multiple functions essential to new vessel formation in the gut mucosa.

CONCLUSIONS

A coordinated and reciprocal interaction of CEACAM1 and microbiota-derived factors is necessary to optimize angiogenesis in the gut mucosa. This suggests that a coordination of endogenous and exogenous innate immune responses is necessary to promote intestinal angiogenesis under physiological and inflammatory conditions such as inflammatory bowel disease.

Single nucleotide polymorphisms in the angiogenic and lymphangiogenic pathways are associated with lymphedema caused by Wuchereria bancrofti

Background

Lymphedema (LE) is a chronic clinical manifestation of filarial nematode infections characterized by lymphatic dysfunction and subsequent accumulation of protein-rich fluid in the interstitial space—lymphatic filariasis. A number of studies have identified single nucleotide polymorphisms (SNPs) associated with primary and secondary LE. To assess SNPs associated with LE caused by lymphatic filariasis, a cross-sectional study of unrelated Ghanaian volunteers was designed to genotype SNPs in 285 LE patients as cases and 682 infected patients without pathology as controls. One hundred thirty-one SNPs in 64 genes were genotyped. The genes were selected based on their roles in inflammatory processes, angiogenesis/lymphangiogenesis, and cell differentiation during tumorigenesis.

Results

Genetic associations with nominal significance were identified for five SNPs in three genes: vascular endothelial growth factor receptor-3 (VEGFR-3) rs75614493, two SNPs in matrix metalloprotease-2 (MMP-2) rs1030868 and rs2241145, and two SNPs in carcinoembryonic antigen-related cell adhesion molecule-1 (CEACAM-1) rs8110904 and rs8111171. Pathway analysis revealed an interplay of genes in the angiogenic/lymphangiogenic pathways. Plasma levels of both MMP-2 and CEACAM-1 were significantly higher in LE cases compared to controls. Functional characterization of the associated SNPs identified genotype GG of CEACAM-1 as the variant influencing the expression of plasma concentration, a novel finding observed in this study.

Conclusion

The SNP associations found in the MMP-2, CEACAM-1, and VEGFR-3 genes indicate that angiogenic/lymphangiogenic pathways are important in LE clinical development.

Electronic supplementary material

The online version of this article (10.1186/s40246-017-0121-7) contains supplementary material, which is available to authorized users.

Protein Expression Differences of 2-Dimensional and Progressive 3-Dimensional Cell Cultures of Non-Small-Cell-Lung-Cancer Cell Line H460

Non-small-cell-lung-cancer (NSCLC) constitutes about 75-80% of lung cancers. The challenge to tackle cancers is in early diagnosis and arriving at safer therapeutic options. In vitro studies using cancer cell lines continue to contribute significantly in understanding cancers. Cell culture methods have evolved and the recent developments in 3 dimensional (3D) cell cultures are inducing greater resemblance of the in vitro cultured cells with in vivo conditions. In this study, we established 3D aggregates of H460 cell line on agarose hydrogels and studied the protein expression differences among cells grown as monolayers (2D) and the progressively developing 3D aggregates from days 2 to 10. Analysis included matching of those proteins expressed by the developing aggregates and the available literature on progressing tumors in vivo. J. Cell. Biochem. 118: 1648-1652, 2017. © 2016 Wiley Periodicals, Inc.

Blood-based biomarkers for monitoring antiangiogenic therapy in non-small cell lung cancer

Tumor angiogenesis pathways have been identified as important therapeutic targets in non-small cell lung cancer. However, no biomarkers have been described as predictors of response to antiangiogenic therapy in these patients. In this study, plasma levels of VEGF, bFGF, E-selectin, and S-ICAM and gene expression profiles of peripheral blood mononuclear cells from non-small cell lung cancer patients treated with chemotherapy plus bevacizumab were analyzed before and after treatment. Values were correlated with clinicopathological characteristics and treatment response. Plasma factor levels were measured using commercially available ELISA kits. The TaqMan(®) human angiogenesis array was used to investigate the effect of treatment on gene expression profiles. Kyoto Encyclopedia of Genes and Genomes and Gene Ontology enrichment analysis was performed for differentially expressed genes using WEB-based GEne SeT AnaLysis Toolkit. Our results suggest a benefit for patients with increased plasma levels of VEGF, E-selectin, and S-ICAM in the course of bevacizumab treatment. Also, we identified differentially expressed genes between paired blood samples from patients before and after treatment, and significantly perturbed pathways were predicted. These changes in gene expression and levels of plasma factors could be used to assess the effectiveness of antiangiogenic therapy, in addition to standard clinical and radiological evaluations.

CEACAM1 is overexpressed in oral tumors and related to tumorigenesis

Carcinoembryonic antigen-related adhesion molecule 1 (CEACAM1) is a type 1 transmembrane glycoprotein belonging to the CEA family, which has been known to exist as either soluble forms in body fluids or membrane-bound forms on the cell surface. Aberrant CEACAM1 expression is associated with tumorigenesis and has been reported in a variety of human tumors, especially malignancies. The aim of this study is to determine the expression of CEACAM1 in oral tumors, trying to study CEACAM1 different expressions as a function of histotype. CEACAM1 expression was observed by immunohistochemistry (IHC) with mouse anti-human antibody for CEACAM1. IHC was performed using avidin-biotin-diaminobenzidine staining. The results were expressed as average score ± SD (0 = negative/8 = highest) for each histotype. Oral tumors expressed more CEACAM1 than normal tissues including squamous and salivary epithelia (P < 0.05). In malignancies, the squamous cell carcinoma overexpressed CEACAM1, compared to well-differentiated squamous cell with more membranous expression; the intermediately and poorly differentiated squamous cell carcinoma showed more cytoplasmic expression (P < 0.05). In addition, the salivary tumors significantly expressed more CEACAM1 than squamous cell carcinoma (P < 0.05). So, we thought oral tumors overexpressed CEACAM1 and the cytoplasmic CEACAM1 might be involved in tumorigenesis, and also CEACAM1 might be regarded as a marker of salivary glandular tumors.

A Role for the Long Noncoding RNA SENCR in Commitment and Function of Endothelial Cells

Despite the increasing importance of long noncoding RNA in physiology and disease, their role in endothelial biology remains poorly understood. Growing evidence has highlighted them to be essential regulators of human embryonic stem cell differentiation. SENCR, a vascular-enriched long noncoding RNA, overlaps the Friend Leukemia Integration virus 1 (FLI1) gene, a regulator of endothelial development. Therefore, we wanted to test the hypothesis that SENCR may contribute to mesodermal and endothelial commitment as well as in endothelial function. We thus developed new differentiation protocols allowing generation of endothelial cells from human embryonic stem cells using both directed and hemogenic routes. The expression of SENCR was markedly regulated during endothelial commitment using both protocols. SENCR did not control the pluripotency of pluripotent cells; however its overexpression significantly potentiated early mesodermal and endothelial commitment. In human umbilical endothelial cell (HUVEC), SENCR induced proliferation, migration, and angiogenesis. SENCR expression was altered in vascular tissue and cells derived from patients with critical limb ischemia and premature coronary artery disease compared to controls. Here, we showed that SENCR contributes to the regulation of endothelial differentiation from pluripotent cells and controls the angiogenic capacity of HUVEC. These data give novel insight into the regulatory processes involved in endothelial development and function.

Kaposi's Sarcoma-Associated Herpesvirus Interleukin-6 Modulates Endothelial Cell Movement by Upregulating Cellular Genes Involved in Migration

Kaposi’s sarcoma-associated herpesvirus (KSHV) is the causative agent of human Kaposi’s sarcoma, a tumor that arises from endothelial cells, as well as two B cell lymphoproliferative diseases, primary effusion lymphoma and multicentric Castleman’s disease. KSHV utilizes a variety of mechanisms to evade host immune responses and promote cellular transformation and growth in order to persist for the life of the host. A viral homolog of human interleukin-6 (hIL-6) named viral interleukin-6 (vIL-6) is encoded by KSHV and expressed in KSHV-associated cancers. Similar to hIL-6, vIL-6 is secreted, but the majority of vIL-6 is retained within the endoplasmic reticulum, where it can initiate functional signaling through part of the interleukin-6 receptor complex. We sought to determine how intracellular vIL-6 modulates the host endothelial cell environment by analyzing vIL-6’s impact on the endothelial cell transcriptome. vIL-6 significantly altered the expression of many cellular genes associated with cell migration. In particular, vIL-6 upregulated the host factor carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) at the protein and message levels. CEACAM1 has been implicated in tumor invasion and metastasis and promotes migration and vascular remodeling in endothelial cells. We report that vIL-6 upregulates CEACAM1 by a STAT3-dependent mechanism and that CEACAM1 promotes vIL-6-mediated migration. Furthermore, latent and de novo KSHV infections of endothelial cells also induce CEACAM1 expression. Collectively, our data suggest that vIL-6 modulates endothelial cell migration by upregulating the expression of cellular factors, including CEACAM1.

Kaposi’s sarcoma-associated herpesvirus (KSHV) is linked with the development of three human malignancies, Kaposi’s sarcoma, multicentric Castleman’s disease, and primary effusion lymphoma. KSHV expresses many factors that enable the virus to manipulate the host environment in order to persist and induce disease. The viral interleukin-6 (vIL-6) produced by KSHV is structurally and functionally homologous to the human cytokine interleukin-6, except that vIL-6 is secreted slowly and functions primarily from inside the host cell. To investigate the unique intracellular role of vIL-6, we analyzed the impact of vIL-6 on endothelial cell gene expression. We report that vIL-6 significantly alters the expression of genes associated with cell movement, including that for CEACAM1. The gene for CEACAM1 was upregulated by vIL-6 and by latent and primary KSHV infection and promotes vIL-6-mediated endothelial cell migration. This work advances the field’s understanding of vIL-6 function and its contribution to KSHV pathogenesis.

Carcinoembryonic antigen-related cell adhesion molecule 1 is expressed and as a function histotype in ovarian tumors

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is a cell-cell adhesion receptor and is implicated in several cellular functions. It is rarely reported in ovarian tumors. The aim of this study is to determine the expression of CEACAM1 in ovarian tumors, trying to see whether CEACAM1 has different expression patterns as a function of histotype. Antigen expression was examined by immunohistochemistry with mouse anti-human antibody for CEACAM1. Immunohistochemistry was performed using avidin-biotin-diaminobenzide staining. The results were expressed as average score ± SD (0, negative; 8, highest) for each histotype. In ovarian tumors, the benign serous and mucinous cystadenoma negatively or weakly expressed CEACAM1, the malignant epithelial tumors strongly expressed CEACAM1, and there was significant difference between benign epithelial tumor and adenocarcinoma (P < .05). The well-differentiated serous adenocarcinoma expressed CEACAM1 mainly with membrane pattern, and the intermediately and poorly differentiated serous adenocarcinomas expressed CEACAM1 mainly with cytoplasmic pattern (P < .05). In addition, CEACAM1 expression is elevated in solid tumors of ovary but variable as a function of histotype. Compared with membranous expression, the cytoplasmic expression was observed almost in metastatic carcinoma that might decrease the adhesive interactions of the carcinoma cells with the surrounding cells, especially with tumor cells, and this could facilitate the tumor cells to metastasize to distant regions. So, we thought that cytoplasmic CEACAM1 might play an important role in tumor progression, especially in tumor metastasis.

CEACAM1-4L Promotes Anchorage-Independent Growth in Melanoma

Widespread metastasis is the leading course of death in many types of cancer, including malignant melanoma. The process of metastasis can be divided into a number of complex cell biological events, collectively termed the “invasion-metastasis cascade.” Previous reports have characterized the capability of anchorage-independent growth of cancer cells in vitro as a key characteristic of highly aggressive tumor cells, particularly with respect to metastatic potential. Biological heterogeneity as well as drastic alterations in cell adhesion of disseminated cancer cells support escape mechanisms for metastases to overcome conventional therapies. Here, we show that exclusively the carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) splice variant CEACAM1-4L supports an anchorage-independent signature in malignant melanoma. These results highlight important variant-specific modulatory functions of CEACAM1 for metastatic spread in patients suffering malignant melanoma.

Down-regulation of CEACAM1 in breast cancer

Carcinoembryonic antigen-related adhesion molecule 1 (CEACAM1) is a type 1 transmembrane glycoprotein belonging to the CEA family, which has been found to exist as either soluble forms in body fluids or membrane-bound forms on the cell surface. Aberrant CEACAM1 expression is associated with tumor progression and has been found in a variety of human malignancies. Increasing interest has been devoted to the expression of CEACAM1 in breast cancer, but most of these findings are contradictory. The aim of this study was to investigate CEACAM1 expression in breast cancer in greater detail. Using immunohistochemical staining, we found that CEACAM1 expression was reduced or lost in breast cancer tissues compared with noncancerous breast tissues. In addition, soluble CEACAM1 levels in the culture medium of breast cancer cell lines were significantly lower than those in a nontumorigenic breast epithelial cell line. Immunofluorescence analysis consistently showed that breast cancer cell lines have relatively low expression of membrane-bound CEACAM1. Furthermore, CEACAM1 mRNA and protein expression levels were down-regulated in breast cancer cell lines as measured using real-time reverse transcriptase-polymerase chain reaction and western blot analysis, respectively. Taken together, our results demonstrate a systematic down-regulation of CEACAM1 in breast cancer and suggest that a strategy to restore CEACAM1 expression may be helpful for the treatment of breast cancer.

Crosstalk of carcinoembryonic antigen and transforming growth factor-β via their receptors: comparing human and canine cancer

There is accumulating evidence that the transforming growth factor beta (TGF-β) and nuclear factor kappa-B (NFκB) pathways are tightly connected and play a key role in malignant transformation in cancer. Immune infiltration by regulatory T- and B-lymphocytes (Tregs, Bregs) has recently gained increased attention for being an important source of TGF-β. There is a plethora of studies examining the pro-tumorigenic functions of carcinoembryonic antigen (CEA), but its receptor CEAR is far less studied. So far, there is a single connecting report that TGF-β also may signal through CEAR. The crosstalk between cancer tissues is further complicated by the expression of CEAR and TGF-β receptors in stromal cells, and implications of TGF-β in epithelial–mesenchymal transition. Furthermore, tumor-infiltrating Tregs and Bregs may directly instruct cancer cells by secreting TGF-β binding to their CEAR. Therefore, both TGF-β and CEA may act synergistically in breast cancer and cause disease progression, and NFκB could be a common crossing point between their signaling. CEAR, TGF-β1–3, TGF-β-R types I–III and NFκB class I and II molecules have an outstanding human–canine sequence identity, and only a canine CEA homolog has not yet been identified. For these reasons, the dog may be a valid translational model patient for investigating the crosstalk of the interconnected CEA and TGF-β networks.

CEACAM1-3S Drives Melanoma Cells into NK Cell-Mediated Cytolysis and Enhances Patient Survival

CEACAM1 is a widely expressed multifunctional cell-cell adhesion protein reported to serve as a poor prognosis marker in melanoma patients. In this study, we examine the functional and clinical contributions of the four splice isoforms of CEACAM1. Specifically, we present in vitro and in vivo evidence that they affect melanoma progression and immune surveillance in a negative or positive manner that is isoform specific in action. In contrast with isoforms CEACAM1-4S and CEACAM1-4L, expression of isoforms CEACAM1-3S and CEACAM1-3L is induced during disease progression shown to correlate with clinical stage. Unexpectedly, overall survival was prolonged in patients with advanced melanomas expressing CEACAM1-3S. The favorable effects of CEACAM1-3S related to enhanced immunogenicity, which was mediated by cell surface upregulation of NKG2D receptor ligands, thereby sensitizing melanoma cells to lysis by natural killer cells. Conversely, CEACAM1-4L downregulated cell surface levels of the NKG2D ligands MICA and ULBP2 by enhanced shedding, thereby promoting malignant character. Overall, our results define the splice isoform-specific immunomodulatory and cell biologic functions of CEACAM1 in melanoma pathogenesis.

Signaling by epithelial members of the CEACAM family - mucosal docking sites for pathogenic bacteria

Carcinoembryonic antigen-related cell adhesion molecules (CEACAMs) comprise a group of immunoglobulin-related vertebrate glycoproteins. Several family members, including CEACAM1, CEA, and CEACAM6, are found on epithelial tissues throughout the human body. As they modulate diverse cellular functions, their signaling capacity is in the focus of current research. In this review we will summarize the knowledge about common signaling processes initiated by epithelial CEACAMs and suggest a model of signal transduction by CEACAM family members lacking significant cytoplasmic domains. As pathogenic and non-pathogenic bacteria exploit these receptors during mucosal colonization, we try to highlight the connection between CEACAMs, microbes, and cellular responses. Special emphasis in this context is placed on the functional interplay between CEACAMs and integrins that influences matrix adhesion of epithelial cells. The cooperation between these two receptor families provides an intriguing example of the fine tuning of cellular responses and their manipulation by specialized microorganisms.

Mycophenolic acid inhibits migration and invasion of gastric cancer cells via multiple molecular pathways

Mycophenolic acid (MPA) is the metabolized product and active element of mycophenolate mofetil (MMF) that has been widely used for the prevention of acute graft rejection. MPA potently inhibits inosine monophosphate dehydrogenase (IMPDH) that is up-regulated in many tumors and MPA is known to inhibit cancer cell proliferation as well as fibroblast and endothelial cell migration. In this study, we demonstrated for the first time MPA’s antimigratory and anti-invasion abilities of MPA-sensitive AGS (gastric cancer) cells. Genome-wide expression analyses using Illumina whole genome microarrays identified 50 genes with ≥2 fold changes and 15 genes with > 4 fold alterations and multiple molecular pathways implicated in cell migration. Real-time RT-PCR analyses of selected genes also confirmed the expression differences. Furthermore, targeted proteomic analyses identified several proteins altered by MPA treatment. Our results indicate that MPA modulates gastric cancer cell migration through down-regulation of a large number of genes (PRKCA, DOCK1, INF2, HSPA5, LRP8 and PDGFRA) and proteins (PRKCA, AKT, SRC, CD147 and MMP1) with promigratory functions as well as up-regulation of a number of genes with antimigratory functions (ATF3, SMAD3, CITED2 and CEAMCAM1). However, a few genes that may promote migration (CYR61 and NOS3) were up-regulated. Therefore, MPA’s overall antimigratory role on cancer cells reflects a balance between promigratory and antimigratory signals influenced by MPA treatment.

Clinical and experimental studies regarding the expression and diagnostic value of carcinoembryonic antigen-related cell adhesion molecule 1 in non-small-cell lung cancer

Background

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is a multifunctional Ig-like cell adhesion molecule that has a wide range of biological functions. According to previous reports, serum CEACAM1 is dysregulated in different malignant tumours and associated with tumour progression. However, the serum CEACAM1 expression in non-small-cell lung carcinomas (NSCLC) is unclear. The different expression ratio of CEACAM1-S and CEACAM1-L isoform has seldom been investigated in NSCLC. This research is intended to study the serum CEACAM1 and the ratio of CEACAM1-S/L isoforms in NSCLC.

Methods

The expression of the serum CEACAM1 was determined by enzyme-linked immunosorbent assay. The protein expression and the location of CEACAM1 in tumours were observed by immunohistochemical staining. The CEACAM1 mRNA levels in tumour and normal adjacent tissues were measured using quantitative real-time PCR, and the expression patterns and the rate of CEACAM1-S and CEACAM1-L were analysed by reverse transcription-PCR.

Results

Serum CEACAM1 levels were significantly higher in NSCLC patients compared with that from normal healthy controls (P <0.0001). 17 patients (81%) among 21 showed high expression of CEACAM1 by immunohistochemical staining. Although no significant differences were found between tumour and normal tissues on mRNA expression levels of CEACAM1 (P >0.05), the CEACAM1-S and the CEACAM1-S/L (S: L) ratios were significantly higher in tumour than normal tissues (P <0.05).

Conclusions

Our data indicated that the serum levels of CEACAM1 could discriminate lung cancer patients from health donors and that CEACAM1 might be a useful marker in early diagnosis of NSCLC. Moreover, our results showed that the expression patterns of CEACAM1 isoforms could be changed during oncogenesis, even when total CEACAM1 in tumour tissues did not show significant changes. Our study suggested that the expression ratios of CEACAM1-S/CEACAM1-L might be a better diagnostic indicator in NSCLC than the quantitative changes of CEACAM1.

CEACAM1 deficiency delays important wound healing processes

Cutaneous wound healing is a complex process that requires the coordination of many cell types to achieve proper tissue repair. Four major overlapping processes have been identified in wound healing: hemostasis, inflammation, reepithelialization and granulation tissue formation, and tissue remodeling. Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is a glycoprotein expressed in epithelial, endothelial, lymphoid, and myeloid cells. Given its known roles in angiogenesis, cell migration, and immune functions, we hypothesized that CEACAM1 might also be involved in cutaneous wound healing and that a number of relevant CEACAM1-positive cell types might contribute to wound healing. To evaluate the role of CEACAM1 in these processes, 6-mm-diameter skin wounds were inflicted on Ceacam1(-/-) and wild-type mice. Herein, we demonstrate that CEACAM1 deletion indeed affects wound healing in three key ways. Infiltration of F4/80(+) macrophages was decreased in Ceacam1(-/-) wounds, altering inflammatory processes. Reepithelialization in Ceacam1(-/-) wounds was delayed. Furthermore, the vascular density of the granulation tissue in Ceacam1(-/-) wounds was significantly diminished. These results confirm CEACAM1's role as an important regulator of key processes in cutaneous wound healing, although whether this works via a specific cell type or alterations in the functioning of multiple processes remains to be determined.

Tumor angiogenesis mediated by myeloid cells is negatively regulated by CEACAM1

Bv8 (prokineticin 2) expressed by Gr1(+)CD11b(+) myeloid cells is critical for VEGF-independent tumor angiogenesis. Although granulocyte colony-stimulating factor (G-CSF) has been shown to be a key inducer of Bv8 expression, the basis for Bv8 production in driving tumor angiogenesis is undefined. Because the cell adhesion molecule CEACAM1, which is highly expressed on Gr1(+)CD11b(+) myeloid cells, is known to regulate G-CSF receptor (G-CSFR) signaling, we hypothesized that CEACAM1 would regulate Bv8 production in these cells. In support of this hypothesis, we found that Bv8 expression was elevated in Gr1(+)CD11b(+) cells from Ceacam1-deficient mice implanted with B16 melanoma, increasing the infiltration of Gr1(+)CD11b(+) myeloid cells in melanoma tumors and enhancing their growth and angiogenesis. Furthermore, treatment with anti-Gr1 or anti-Bv8 or anti-G-CSF monoclonal antibody reduced myeloid cell infiltration, tumor growth, and angiogenesis to levels observed in tumor-bearing wild-type (WT) mice. Reconstitution of CEACAM1-deficient mice with WT bone marrow cells restored tumor infiltration of Gr1(+)CD11b(+) cells along with tumor growth and angiogenesis to WT levels. Treatment of tumor-bearing WT mice with anti-CEACAM1 antibody limited tumor outgrowth and angiogenesis, albeit to a lesser extent. Tumor growth in Ceacam1-deficient mice was not affected significantly in Rag(-/-) background, indicating that CEACAM1 expression in T and B lymphocytes had a negligible role in this pathway. Together, our findings show that CEACAM1 negatively regulates Gr1(+)CD11b(+) myeloid cell-dependent tumor angiogenesis by inhibiting the G-CSF-Bv8 signaling pathway.

The evaluation of SOX9 expression and its relationship with carcinoembryonic antigen-related cell adhesion molecule 1 in gastric neoplastic and nonneoplastic lesions

The aims of this study were to investigate the expression of SOX9 (sex determining region Y [SRY]-related high-mobility group box 9) and carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) in benign, premalignant, and malignant gastric lesions and to explore the association between SOX9 and CEACAM1 in gastric carcinogenesis. SOX9 and CEACAM1 expression was detected in normal gastric mucosa, hyperplastic polyp, intestinal metaplasia, gastric intraepithelial neoplasia, and adenocarcinoma by immunohistochemistry. There was low expression of SOX9 and no CEACAM1 expression in normal gastric mucosa and hyperplastic polyps. Intestinal metaplasia began to express CEACAM1 and showed more membranous staining of CEACAM1 than normal mucosa and hyperplastic polyps (P = .000), but SOX9 expression had no significant difference, and the coexpression of SOX9 and CEACAM1 ascended; therefore, the difference was significant (P = .000). Gastric intraepithelial neoplasia showed more SOX9 expression, coexpression of SOX9, and CEACAM1 than in intestinal metaplasia (P = .014 and P = .026, respectively). Carcinoma showed more cytoplasmic CEACAM1 (P = .010), more SOX9 expression (P = .001), and more their coexpression (P = .023) than gastric intraepithelial neoplasia. As to the histologic classification, poorly differentiated carcinoma showed more cytoplasmic CEACAM1 than well and moderately differentiated carcinoma (P = .006 and P = .024, respectively). In the Laurén classification, diffuse carcinoma showed more cytoplasmic CEACAM1 than intestinal carcinoma (P = .0035), but the SOX9 expression and their coexpresison showed no difference (P = .065 and P = .074, respectively). With the elevation of SOX9 expression and the changing of CEACAM1 expression patterns, the coexpressions of SOX9 and CEACAM1 were highly elevated from benign proliferative lesions to malignant lesions. Moreover, the SOX9 expression and the coexpression with CEACAM1 were correlated positively (r = 0.310; P = .015). In addition, SOX9 expression was positively correlated with CEACAM1 expression patterns (r = 0.124; P = .032). In addition, CEACAM1 expression patterns and coexpression of SOX9 and CEACAM1 show significant difference between T1 and T2 and T3 and T4 (P = .021 and P = .011, respectively). Accordingly, compared with N0, N2 and N3 showed significant difference in SOX9 expression (P = .018), CEACAM1 expression patterns (P = .010), and their coexpression (P = .010). SOX9 expression significantly increased from nonneoplastic lesions to neoplastic lesions, and CEACAM1 expression patterns markedly changed; their coexpression also showed signally elevated suggesting that SOX9, as a transcriptional regulator, play important roles in the changing of CEACAM1 expression patterns, which might promote the tumor progression.

Two new synthetic peptides from the N-domain of CEACAM1 (CD66a) stimulate neutrophil adhesion to endothelial cells

Four members of the carcinoembryonic antigen family, CEACAMs 1, 3, 6, and 8, are expressed on human neutrophils and can trigger an activation signal that increases neutrophil adhesion to human umbilical vein endothelial cell (HUVEC) monolayers. To identify active sites on CEACAM1, we previously performed molecular modeling using IgG and CD4 as models, and 28 peptides of 14 amino acids in length were synthesized that were predicted to be present at loops and turns between β-sheets. Three peptides, each from the N-terminal domain, increased neutrophil adhesion to HUVEC monolayers and upregulated cell-surface CD11b/CD18 expression on neutrophils. In our earlier study, one N-domain peptide (CD66a-7) was not successfully synthesized, and another N-domain peptide (CD66a-6) was not soluble in the assay system. In the present study, we have now successfully synthesized CD66a-7, and a new peptide (CD66a-6L), that is a modification of the peptide that was insoluble in the earlier study. Both of these new peptides increased neutrophil adhesion to HUVEC monolayers. Importantly, the amino acid sequence of CD66a-7 is identical to the homologous peptides from CEACAMs 3, 5, and 6, but differs from the homologous peptide of CEACAM8, which was not active in this system. CD66a-6L is identical to the homologous peptide from CEACAM6. The data suggest that peptide motifs from at least five regions of the N-terminal domain of CEACAM1 are involved in the interaction of CEACAM1 with other ligands and can initiate signal transduction in neutrophils. Some of these active peptides are identical to homologous regions of other CEACAMs.

The possible roles of OPN-regulated CEACAM1 expression in promoting the survival of activated T cells and the apoptosis of oral keratinocytes in oral lichen planus patients

Oral lichen planus is a chronic inflammatory disorder of the oral mucosa that represents T cell-mediated autoimmune diseases. The regulation and roles of carcinoembryonic antigen-related cellular adhesion molecule 1 (CEACAM1), a novel immune molecule, in the immunopathogenesis of T cell-mediated autoimmune diseases remain unclear. In the current paper, CEACAM1 was found to be overexpressed in peripheral T cells and epithelial cells in oral lichen planus patients. A fraction of infiltrating inflammatory mononuclear cells in the lamina propria of the oral lichen planus mucosa also expressed CEACAM1. Importantly, for the first time, CEACAM1 expression in T cells and in normal human oral keratinocytes was demonstrated to be regulated differently by osteopontin in vitro. Furthermore, the apoptosis of oral keratinocytes and activated T cells can be markedly suppressed by CEACAM1-specific monoclonal antibodies. In conclusion, OPN-regulated CEACAM1 expression may play a critical role in the immunopathogenesis of oral lichen planus.

Different expression patterns of CEACAM1 and its impacts on angiogenesis in gastric nonneoplastic and neoplastic lesions

OBJECTIVE

This study was designed to investigate the expression patterns of CEACAM1 and its relationship with angiogenesis in nonneoplastic and neoplastic gastric lesions.

METHODS

CEACAM1 and TGF-β expression was detected by immunohistochemical staining and dual-labeling immunohistochemical staining in neoplastic and nonneoplastic lesions. MVD-CD31 and MVD-CD105 were counted in CEACAM1-positive areas by dual-labeling immunohistochemistry.

RESULTS

There was no expression of CEACAM1 in normal gastric mucosa. In IM and GIN, CEACAM1 was mainly expressed with membranous pattern. CEACAM1 was expressed with membranous pattern in well-differentiated adenocarcinoma, with cytoplasmic pattern in poorly differentiated adenocarcinoma, and with cytoplasmic and membranous pattern mixed together in intermediately adenocarcinoma. The expression patterns of CEACAM1 showed a significant difference (P < 0.05) in nonneoplastic and neoplastic lesions. Coexpression of CEACAM1 and TGF-β was elevated and significantly different from nonneoplastic to neoplastic lesions (P < 0.05). Moreover, CEACAM1 and TGF-β coexpression were related to carcinoma progression (r = 0.35; P < 0.05). MVD-CD31 and MVD-CD105 showed significant differences from nonneoplastic to neoplastic lesions (P < 0.05).

CONCLUSIONS

CEACAM1 has different expression patterns in nonneoplastic and neoplastic lesions. The coexpression of CEACAM1 and TGF-β increased from nonneoplastic to neoplastic lesions and may be related with tumor progression via promoting tumorous angiogenesis.

Apical expression of human full-length hCEACAM1-4L protein renders the Madin Darby Canine Kidney cells responsive to lipopolysaccharide leading to TLR4-dependent Erk1/2 and p38 MAPK signalling

CEACAM1 expressed by granulocytes and epithelial cells is recognized as a membrane-associated receptor by some Gram-negative pathogens. Here we report a previously unsuspected role of human CEACAM1-4L (hCEACAM1-4L) in polarized epithelial cells. We find that in contrast with non-transfected cells, Madin Darby Canine Kidney strain II (MDCK) engineered for the apical expression of the long cytoplasmic chain protein hCEACAM1-4L showed a serum-independent increase in the phosphorylation of the extracellular signal-regulated kinase 1/2 (Erk1/2) and p38 mitogen-activated protein kinases (MAPKs) after treatment with lipopolysaccharide (LPS) of wild-type, diffusely adhering Afa/Dr Escherichia coli (Afa/Dr DAEC) strain IH11128. Aggregates of FITC-LPS bind the apical domain of MDCK-hCEACAM1-4L cells colocalizing with the apically expressed hCEACAM1-4L protein and do not bind MDCK-pCEP cells, and surface plasmon resonance analysis shows that LPS binds to the extracellular domain of the CEACAM1-4L protein. We showed that cell polarization and lipid rafts positively control the LPS-IH11128-induced phosphorylation of Erk1/2 in MDCK-hCEACAM1-4L cells. Structure-function analysis using mutated hCEACAM1-4L protein shows that the cytoplasmic domain of the protein is needed for LPS-induced MAPK signalling, and that phosphorylation of Tyr-residues is not increased in association with MAPK signalling. The hCEACAM1-4L-dependent Erk1/2 phosphorylation develops in the presence of lipid A and does not develop in the presence of penta-acylated LPS. Finally, small interfering RNA (siRNA) silencing of canine TLR4 abolishes the hCEACAM1-4L-dependent, LPS-induced phosphorylation of Erk1/2. Collectively, our results support the notion that the apically expressed, full-length hCEACAM1-4L protein functions as a novel LPS-conveying molecule at the mucosal surface of polarized epithelial cells for subsequent MD-2/TLR4 receptor-dependent MAPK Erk1/2 and p38 signalling.

CEACAM1: a key regulator of vascular permeability

Carcinoembryonic antigen cell adhesion molecule-1 (CEACAM1) is an immunoglobulin-like cell surface co-receptor expressed on epithelial, hematopoietic and endothelial cells. CEACAM1 functions as an adhesion molecule, mainly binding to itself or other members of the CEA family. We and others have previously shown that CEACAM1 is crucial for in vivo vascular integrity during ischemic neo-vascularization. Here, we have deciphered the roles of CEACAM1 in normal and pathological vascularization. We have found that Ceacam1−/− mice exhibit a significant increase in basal vascular permeability related to increased basal Akt and endothelial nitric oxide synthase (eNOS) activation in primary murine lung endothelial cells (MLECs). Moreover, CEACAM1 deletion in MLECs inhibits VEGF-mediated nitric oxide (NO) production, consistent with defective VEGF-dependent in vivo permeability in Ceacam1−/− mice. In addition, Ceacam1-null mice exhibit increased permeability of tumor vasculature. Finally, we demonstrate that CEACAM1 is tyrosine-phosphorylated upon VEGF treatment in a SHP-1- and Src-dependent manner, and that the key residues of the long cytoplasmic domain of CEACAM1 are crucial for CEACAM1 phosphorylation and NO production. This data represents the first report, to our knowledge, of a functional link between CEACAM1 and the VEGFR2/Akt/eNOS-mediated vascular permeability pathway.

Homophilic adhesion and CEACAM1-S regulate dimerization of CEACAM1-L and recruitment of SHP-2 and c-Src

Carcinoembryonic antigen (CEA)-related cell adhesion molecule 1 (CAM1 [CEACAM1]) mediates homophilic cell adhesion and regulates signaling. Although there is evidence that CEACAM1 binds and activates SHP-1, SHP-2, and c-Src, knowledge about the mechanism of transmembrane signaling is lacking. To analyze the regulation of SHP-1/SHP-2/c-Src binding, we expressed various CFP/YFP-tagged CEACAM1 isoforms in epithelial cells. The supramolecular organization of CEACAM1 was examined by cross-linking, coclustering, coimmunoprecipitation, and fluorescence resonance energy transfer. SHP-1/SHP-2/c-Src binding was monitored by coimmunoprecipitation and phosphotyrosine-induced recruitment to CEACAM1-L in cellular monolayers. We find that trans-homophilic CEACAM1 binding induces cis-dimerization by an allosteric mechanism transmitted by the N-terminal immunoglobulin-like domain. The balance of SHP-2 and c-Src binding is dependent on the monomer/dimer equilibrium of CEACAM1-L and is regulated by trans-binding, whereas SHP-1 does not bind under physiological conditions. CEACAM1-L homodimer formation is reduced by coexpression of CEACAM1-S and modulated by antibody ligation. These data suggest that transmembrane signaling by CEACAM1 operates by alteration of the monomer/dimer equilibrium, which leads to changes in the SHP-2/c-Src-binding ratio.

The CEACAM1 N-terminal Ig domain mediates cis- and trans-binding and is essential for allosteric rearrangements of CEACAM1 microclusters

Cell adhesion molecules (CAMs) sense the extracellular microenvironment and transmit signals to the intracellular compartment. In this investigation, we addressed the mechanism of signal generation by ectodomains of single-pass transmembrane homophilic CAMs. We analyzed the structure and homophilic interactions of carcinoembryonic antigen (CEA)-related CAM 1 (CEACAM1), which regulates cell proliferation, apoptosis, motility, morphogenesis, and microbial responses. Soluble and membrane-attached CEACAM1 ectodomains were investigated by surface plasmon resonance-based biosensor analysis, molecular electron tomography, and chemical cross-linking. The CEACAM1 ectodomain, which is composed of four glycosylated immunoglobulin-like (Ig) domains, is highly flexible and participates in both antiparallel (trans) and parallel (cis) homophilic binding. Membrane-attached CEACAM1 ectodomains form microclusters in which all four Ig domains participate. Trans-binding between the N-terminal Ig domains increases formation of CEACAM1 cis-dimers and changes CEACAM1 interactions within the microclusters. These data suggest that CEACAM1 transmembrane signaling is initiated by adhesion-regulated changes of cis-interactions that are transmitted to the inner phase of the plasma membrane.

[CEACAM1 as a central modulator of metabolism, tumor progression, angiogenesis and immunity]

CEACAM1 (carcinoembryonic antigen cell adhesion molecule 1), a member of the immunoglobulin (Ig) superfamily, is a heavily glycosylated protein. This glycoprotein exhibits an intracytoplasmic region that can be either long (71-73 amino acids) with two inhibitory tyrosine-phosphorylated motifs and several phosphorylated serine residues, or short (10 amino acid). CEACAM1 is a multifunctional protein that plays a role in intercellular adhesion, as an inhibitor of tumor development, as a bacterial adhesin, and as a receptor for the mouse hepatitis virus. Moreover, CEACAM1 is an active regulator of cell signaling, modulating the insulin or EGF receptor pathways in epithelial cells or the Zap-70 pathway in hematopoietic cells. The recent development of genetically modified mouse models altering the Ceacam1 gene corroborates most of these data, but also highlights CEACAM1's functional complexity. Thus, in addition to the functions identified previously, CEACAM1 is an important regulator of lipid metabolism, of tumor progression as a regulator of the Wnt signaling pathway, of normal and tumor neo-angiogenesis and of immunity.

CEACAM1 distribution and it's effects on angiogenesis and lymphangiogenesis in oral carcinoma

To investigate the expression of carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) and its effects on angiogenesis and lymphangiogenesis in oral carcinoma. Immunohistochemistry was used to study the expression of CEACAM1, LYVE1 and CD31, double-labelling immunofluorescence was used to detect the co-expression of CEACAM1 and LYVE1, and double-labelling immunohistochemistry was performed to observe the co-expression of LYVE1 and CD31 in vessels. Membranous CEACAM1 was expressed in well-differentiated squamous cell carcinoma and cytoplastic CEACAM1 in poorly and moderately differentiated carcinoma (P<0.05). More CEACAM1-positive vessels were observed in CEACAM1-positive tumors with cytoplasmic expression than with membranous expression (P<0.001). Co-expression of CEACAM1 and LYVE1, LYVE1 and CD31 in vessels was more common in CEACAM1-positive tumors with cytoplasmic expression than with membranous expression (P<0.001). CEACAM1 has different distribution in oral carcinoma. Membranous CEACAM1 inhibits angiogenesis and lymphangiogenesis, but cytoplasmic CEACAM1 promotes angiogenesis, and even promotes lymphangiogenesis by mediating the transformation of vascular endothelial cells (VECs) into lymphatic endothelial cells (LECs).

Interdependency of CEACAM-1, -3, -6, and -8 induced human neutrophil adhesion to endothelial cells

Members of the carcinoembryonic antigen family (CEACAMs) are widely expressed, and, depending on the tissue, capable of regulating diverse functions including tumor promotion, tumor suppression, angiogenesis, and neutrophil activation. Four members of this family, CEACAM1, CEACAM8, CEACAM6, and CEACAM3 (recognized by CD66a, CD66b, CD66c, and CD66d mAbs, respectively), are expressed on human neutrophils. CD66a, CD66b, CD66c, and CD66d antibodies each increase neutrophil adhesion to human umbilical vein endothelial cell monolayers. This increase in neutrophil adhesion caused by CD66 antibodies is blocked by CD18 mAbs and is associated with upregulation of CD11/CD18 on the neutrophil surface. To examine potential interactions of CEACAMs in neutrophil signaling, the effects on neutrophil adhesion to human umbilical vein endothelial cells of a set of CD66 mAbs was tested following desensitization to stimulation by various combinations of these mAbs. Addition of a CD66 mAb in the absence of calcium results in desensitization of neutrophils to stimulation by that CD66 mAb. The current data show that desensitization of neutrophils to any two CEACAMs results in selective desensitization to those two CEACAMs, while the cells remain responsive to the other two neutrophil CEACAMs. In addition, cells desensitized to CEACAM-3, -6, and -8 were still responsive to stimulation of CEACAM1 by CD66a mAbs. In contrast, desensitization of cells to CEACAM1 and any two of the other CEACAMs left the cells unresponsive to all CD66 mAbs. Cells desensitized to any combination of CEACAMs remained responsive to the unrelated control protein CD63. Thus, while there is significant independence of the four neutrophil CEACAMs in signaling, CEACAM1 appears to play a unique role among the neutrophil CEACAMs. A model in which CEACAMs dimerize to form signaling complexes could accommodate the observations. Similar interactions may occur in other cells expressing CEACAMs.

Monocyte chemotactic protein-1 regulates voltage-gated K+ channels and macrophage transmigration

Progressive human immunodeficiency virus (HIV)-1 infection and virus-induced neuroinflammatory responses effectuate monocyte-macrophage transmigration across the blood-brain barrier (BBB). A key factor in mediating these events is monocyte chemotactic protein-1 (MCP-1). Upregulated glial-derived MCP-1 in HIV-1-infected brain tissues generates a gradient for monocyte recruitment into the nervous system. We posit that the inter-relationships between MCP-1, voltage-gated ion channels, cell shape and volume, and cell mobility underlie monocyte transmigration across the BBB. In this regard, MCP-1 serves both as a chemoattractant and an inducer of monocyte-macrophage ion flux affecting cell shape and mobility. To address this hypothesis, MCP-1-treated bone marrow-derived macrophages (BMM) were analyzed for gene and protein expression, electrophysiology, and capacity to migrate across a laboratory constructed BBB. MCP-1 enhanced K+ channel gene (KCNA3) and channel protein expression. Electrophysiological studies revealed that MCP-1 increased outward K+ currents in a dose-dependent manner. In vitro studies demonstrated that MCP-1 increased BMM migration across an artificial BBB, and the MCP-1-induced BMM migration was blocked by tetraethylammonium, a voltage-gated K+ channel blocker. Together these data demonstrated that MCP-1 affects macrophage migratory movement through regulation of voltage-gated K+ channels and, as such, provides a novel therapeutic strategy for neuroAIDS.

AP-1-controlled hepatocyte growth factor activation promotes keratinocyte migration via CEACAM1 and urokinase plasminogen activator/urokinase plasminogen receptor

Keratinocyte migration is essential for the rapid closure of the epidermis in the process of wound healing. Mesenchymal cell-derived hepatocyte growth factor (HGF) is a central regulator of this process. However, the molecular mechanisms and relevant genes that facilitate this cellular response are still poorly defined. We used heterologous cocultures combining primary human keratinocytes and genetically modified murine fibroblasts to identify key factors mediating HGF-induced epidermal cell migration. The absence of c-Jun activity in fibroblasts completely abolished the expression of HGF in these cells and consequently altered the behavior of keratinocytes. Time-resolved expression series of keratinocytes stimulated with HGF disclosed target genes regulating HGF-dependent motility. In addition to well-established HGF-dependent wound healing-associated genes, carcinoembryogenic antigen-related cell adhesion molecule (CEACAM)-1 and the urokinase plasminogen activator (uPA)/uPA-receptor (uPAR) pathway were identified as possible mediators in HGF-induced keratinocyte migration. The functional relevance of CEACAM-1 and uPA/uPAR on epidermal cell motility was demonstrated using the HaCaT cell culture model. In conclusion, the distinct spatiotemporal regulation of genes by HGF is essential for proper epidermal cell migration in cutaneous wound healing.

Cytokine-induced CEACAM1 expression on keratinocytes is characteristic for psoriatic skin and contributes to a prolonged lifespan of neutrophils

Carcinoembryonic antigen-related cellular adhesion molecule 1 (CEACAM1) is a cell-surface glycoprotein, belonging to the carcinoembryonic antigen family, expressed by human neutrophils, epithelial cells, activated T and NK cells. CEACAM1 is expressed as a cell-surface molecule with different isoforms or can be secreted as a soluble protein. Here, we show that keratinocytes in the outer epidermal layer of psoriatic skin express CEACAM1, unlike those in healthy skin or in cutaneous lesions of patients with atopic or nummular dermatitis. Stimulation of primary human keratinocytes or in vitro reconstituted epidermis with culture supernatants of activated psoriatic lesion-infiltrating T cells, IFN-gamma or oncostatin M, but not IL-17, induced the expression of transcripts for the CEACAM1-long and -short isoforms and cell-surface CEACAM1, whereas soluble CEACAM1 was not produced. The uppermost layers of the epidermis in psoriatic lesions also contain neutrophils, a cell type with inflammatory and antimicrobial properties. Coculture of CEACAM1-expressing keratinocytes or CHO transfectants with neutrophils delayed spontaneous apoptosis of the latter cells. These results show that cytokine-induced cell-surface expression of CEACAM1 by keratinocytes in the context of a psoriatic environment might contribute to the persistence of neutrophils and thus to ongoing inflammation and the decreased propensity for skin infection, typical for patients with psoriasis.

The role of cell adhesion pathways in angiogenesis

Angiogenesis, the formation of new blood vessels from pre-existing vasculature, is prevalent both during normal mammalian development and in certain pathological conditions such as tumor growth. It is stimulated and controlled by a complex network of intracellular signaling mechanisms, many of which are initiated by trans-membrane receptors transducing signals received from other cells and from the extracellular environment. Of these, cytokine signaling is recognized as one of the primary drivers of angiogenesis, but it has become increasingly evident that signaling mechanisms generated as a result of cell adhesion interactions are also crucially important. In addition, cell adhesion pathways are also intimately tied to cytokine signaling often making it difficult to dissect out the relative contribution of each to a particular angiogenic step. Many of these same signaling mechanisms are often manipulated by tumors to stimulate aberrant angiogenesis and enhance their blood supply. As a consequence, there is a great deal of interest in trying to understand the full complement of intracellular signaling pathways in angiogenesis as well as their interplay and timing during the process. Ultimately, understanding the complex network of signaling pathways that function during angiogenesis will provide important avenues for future therapeutic development.

Human interleukin-10 gene transfer is protective in a rat model of Parkinson's disease

In Parkinson's disease (PD) chronic inflammation occurs in the substantia nigra (SNc) concurrently with dopaminergic neurodegeneration. In models of PD, microglial activation precedes neurodegeneration in the SNc, suggesting that the underlying pathogenesis involves a complex response in the nigrostriatal pathway, and that the innate immune system plays a significant role. We have investigated the neuroprotective effect of an adeno-associated viral type-2 (AAV2) vector containing the complementary DNA (cDNA) for human interleukin-10 (hIL-10) in the unilateral 6-hydroxydopamine (6-OHDA) rat model of PD. AAV2-hIL-10 reduced the 6-OHDA-induced loss of tyrosine hydroxylase (TH)-positive neurons in the SNc, and also reduced loss of striatal dopamine (DA). Pretreatment with AAV2-hIL-10 reduced glial activation in the SNc but did not attenuate striatal release of the inflammatory cytokine IL-1beta. Assessment of rotational behavior in response to apomorphine challenge showed absence of asymmetry, confirming protection of dopaminergic innervation of the lesioned striatum. At baseline, 6-OHDA-lesioned animals displayed a deficit in contralateral forelimb use, but pretreatment with AAV2-hIL-10 reduced this forelimb akinesia. Transcriptional analyses revealed alteration of a few genes by AAV2-hIL-10; these alterations may contribute to neuroprotection. This study supports the need for further investigations relating to gene therapies aimed at reducing neuroinflammation in early PD.

Direct interaction of tumor suppressor CEACAM1 with beta catenin: identification of key residues in the long cytoplasmic domain

CEACAM1-4L (carcinoembryonic antigen cell adhesion molecule 1, with 4 extracellular Ig-like domains and a long, 71 amino acid cytoplasmic domain) is expressed in epithelial cells and activated T-cells, but is down-regulated in most epithelial cell cancers and T-cell leukemias. A highly conserved sequence within the cytoplasmic domain has ca 50% sequence homology with Tcf-3 and -4, transcription factors that bind beta-catenin, and to a lesser extent (32% homology), with E-cadherin that also binds beta-catenin. We show by quantitative yeast two-hybrid, BIAcore, GST-pull down, and confocal analyses that this domain directly interacts with beta-catenin, and that H-469 and K-470 are key residues that interact with the armadillo repeats of beta-catenin. Jurkat cells transfected with CEACAM1-4L have 2-fold less activity in the TOPFLASH reporter assay, and in MCF7 breast cancer cells that fail to express CEACAM1, transfection with CEACAM1 and growth in Ca2+ media causes redistribution of beta-catenin from the cytoplasm to the cell membrane, demonstrating a functional role for the long cytoplasmic domain of CEACAM1 in regulation of beta-catenin activity.