CEACAM1, CEA/CEACAM5, and CEACAM6 are cell adhesion molecules (CAMs) of the carcinoembryonic antigen (CEA) family that have been shown to be deregulated in lung cancer and in up to 50% of all human cancers. However, little is known about the functional impact of these molecules on undifferentiated cell growth and tumor progression. Here we demonstrate that cell surface expression of CEACAM1 on confluent A549 human lung adenocarcinoma cells plays a critical role in differentiated, contact-inhibited cell growth. Interestingly, CEACAM1-L, but not CEACAM1-S, negatively regulates proliferation via its ITIM domain, while in proliferating cells no CEACAM expression is detectable. Furthermore, we show for the first time that CEACAM6 acts as an inducer of cellular proliferation in A549 cells, likely by interfering with the contact-inhibiting signal triggered by CEACAM1-4L, leading to undifferentiated anchorage-independent cell growth. We also found that A549 cells expressed significant amounts of non-membrane anchored variants of CEACAM5 and CEACAM6, representing a putative source for the increased CEACAM5/6 serum levels frequently found in lung cancer patients. Taken together, our data suggest that post-confluent contact inhibition is established and maintained by CEACAM1-4L, but disturbances of CEACAM1 signalling by CEACAM1-4S and other CEACAMs lead to undifferentiated cell growth and malignant transformation.

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.

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.

ABSTRACT: BACKGROUND: The objective of this study was to identify demographic, environmental and socioeconomic risk factors and spatial patterns of Plasmodium falciparum parasitaemia in a high endemicity area of Africa, and to specify how this information can facilitate improved malaria control at the district level. METHODS: A questionnaire was administered to about 4,000 schoolchildren in 55 schools in western Cote d'Ivoire to determine children's socioeconomic status and their habit of sleeping under bed nets. Environmental data were obtained from satellite images, digitized ground maps and a second questionnaire addressed to school directors. Finger prick blood samples were collected and P. falciparum parasitaemia determined under a microscope using standardized, quality-controlled methods. Bayesian variogram models were utilized for spatial risk modelling and mapping of P. falciparum parasitaemia at non-sampled locations, assuming stationary and non-stationary underlying spatial dependence. RESULTS: Two-thirds of the schoolchildren were infected with P. falciparum and the mean parasitaemia among infected children was 959 parasites/mul of blood. Age, socioeconomic status, not sleeping under a bed net, coverage rate with bed nets and environmental factors (e.g., normalized difference vegetation index, rainfall, land surface temperature and living in close proximity to standing water) were significantly associated with the risk of P. falciparum parasitaemia. After accounting for spatial correlation, age, bed net coverage, rainfall during the main malaria transmission season and distance to rivers remained significant covariates. CONCLUSION: It is argued that a massive increase in bed net coverage, particularly in villages in close proximity to rivers, in concert with other control measures, is necessary to bring malaria endemicity down to intermediate or low levels.

Hookworms (Ancylostoma duodenale and Necator americanus) are blood-feeding intestinal nematodes that infect ~700 million people worldwide. In order to promote the understanding the systems metabolic response of the mammalian host to hookworm infection, we employed a metabolic profiling strategy involving the combination of 1H NMR spectroscopic analysis of urine and serum and multivariate data analysis techniques - to investigate the biochemical consequences of a N. americanus infection in the hamster. The infection was characterized by an altered energy metabolism, consistent with hookworm-induced anemia. Additionally, a disturbance of gut microbiotal activity was associated with a N. americanus infection, manifested in the alterations of microbial co-metabolites, including phenylacetylglycine, p-cresol glucuronide, 4-hydroxy-3methyl-phenylpropionic acid, hippurate, 4-hydroxyphenylactate, and dimethylamine. The correlation between worm burden and metabolite concentrations also reflected the changes of gut microbiota. Furthermore, elevated levels of urinary 2-aminoadipate was a characteristic feature of the infection, which may be associated with the documented neurological consequences of N. americanus.

The acute phase protein Orosomucoid (ORM), also known as alpha1-acid glycoprotein (AGP), is found to be increased in infection, inflammation and cancer. Recently, we demonstrated that ORM is produced by endothelial cells and detectable in urine samples of patients with bladder cancer. However, it was not clarified yet whether ORM plays a role in new vessel formation. To this aim we performed overexpression and gene silencing for ORM in human micro vascular endothelial cells (HDMECs). ORM purified from human plasma was used individually or in combination with VEGF-A in endothelial tube formation, migration and proliferation assay. The in vivo effect of ORM in angiogenesis was studied using the chicken chorionallantois membrane (CAM) with subsequent counting of blood vessels on histological sections from the stimulated areas of CAM-tissue. Our data show that ORM alone enhances migration but not proliferation of HDMECs. ORM alone does not induce endothelial tubes in vitro but simultaneous application of ORM with VEGF-A increases the number and the network of VEGF-A-induced endothelial tubes. Remarkably, ORM alone induces new vessel formation in vivo using CAM-assay and supports the VEGF-A-induced new vessel formation in this assay. Taken together, our results let assume that ORM has pro-angiogenic properties and supports the angiogenic effect of VEGF-A. Thus, ORM seems to be involved in the regulation of angiogenesis.

OBJECTIVES: Various imaging modalities, such as magnetic resonance imaging (MRI), have been assessed with regard to their value in the detection of prostate cancer (CaP). However, there is a need for less time-consuming and more cost effective procedures in urology. In order to determine the ability of contrast-enhanced transrectal ultrasound (CE-TRUS) to identify CaP, we investigated patients scheduled for radical prostatectomy for CaP and radical cystoprostatectomy for bladder cancer. MATERIAL AND METHODS: Between May and August 2008, 35 consecutive patients with CaP and muscle-invasive bladder carcinoma were prospectively enrolled in this single center study. All patients underwent B-mode TRUS and CE-TRUS (Sequoia 512 unit with an endocavity probe EV8C4, 8 MHz; Siemens, Erlangen, Germany) by one investigator blinded to any clinical data before radical surgery. Contrast-enhanced images were obtained after intravenous infusion of a bolus (2.4 ml) of the contrast agent SonoVue (Bracco, Milan, Italy). Ultrasound findings (CE-TRUS and B-mode TRUS) were correlated with step-section histology. RESULTS: On a per-patient basis, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for detecting CaP with CE-TRUS were 71.0%, 50.0%, 91.7%, and 18.2%, respectively. In comparison with B-mode TRUS (sensitivity 45.2%, specificity 75.0%, PPV 93.3%, and NPV 18.0%), CE-TRUS performed significantly better (P = 0.004, McNemar test). On a per-prostate-lobe basis sensitivity, specificity, PPV, and NPV were 69.0%, 33.3%, 83.3%, and 18.2%. CONCLUSION: CE-TRUS detected prostate cancer with a modest sensitivity and a high PPV in a selected patient cohort. Future randomized-controlled multicenter studies are needed to further validate the value of CE-TRUS in the detection of CaP. Based on our results, CE-TRUS may not be recommended as a routine procedure in the diagnosis of CaP at present.

BACKGROUND: Carcinoembryonic antigen-related cell adhesion molecule 1 (biliary glycoprotein; CEACAM1) is expressed in normal bladder urothelium and in angiogenically activated endothelial cells, where it exhibits proangiogenic properties. OBJECTIVE: The aim of this study was to evaluate the value of urinary CEACAM1 for detection of urothelial carcinoma of the bladder (UCB). DESIGN, SETTING, AND PARTICIPANTS: This prospective study included 175 patients. MEASUREMENTS: Immunohistochemistry for CEACAM1 was performed on UCB sections of 10 patients. Enzyme-linked immunosorbent assay (ELISA) for CEACAM1 was performed on urine specimens of healthy volunteers (n=30), patients with benign prostatic hyperplasia (BPH; n=5), severe cystitis (n=5), non-muscle-invasive UCB (n=72), muscle-invasive UCB (n=21), or past history of UCB without evidence of disease (n=42). Western blot analysis was performed on a subgroup of these subjects (n=53). RESULTS AND LIMITATIONS: CEACAM1 immunostaining in normal urothelium disappears in noninvasive UCB but appears in endothelial cells of adjacent vessels. Western blotting revealed presence of CEACAM1 in the urine of no healthy volunteers, of 76% of noninvasive UCB patients, and of 100% of invasive UCB patients. ELISA analysis confirmed that urinary CEACAM1 levels were significantly higher in UCB patients compared with control subjects (median: 207ng/ml vs 0ng/ml; p<0.001). The area under the curve for UCB detection was 0.870 (95% confidence interval [CI]: 0.810-0.931). In multivariable logistic regression analyses that adjusted for the effects of age and gender, higher CEACAM1 levels were associated with cancer presence (hazard ratio [HR]: 2.89; 95% CI: 2.01-4.15; p<0.001) and muscle-invasive cancer (HR: 5.53; 95% CI: 1.68-18.24; p=0.005). The cut-off level of 110ng/ml yielded sensitivity of 74% and specificity of 95% for detecting UCB. Sensitivity was 88% for detecting high-grade UCB and 100% for detecting invasive-stage UCB. Larger studies are necessary to establish the diagnostic and prognostic roles of this highly promising novel marker in UCB. CONCLUSIONS: Urinary CEACAM1 levels discriminate UCB patients from non-UCB subjects. Moreover, urinary levels of CEACAM1 increased with advancing stage and grade.

In the past three decades many efforts have been undertaken to understand the mechanisms of tumor angiogenesis. The introduction of anti-angiogenic drugs in tumor therapy during the last few years necessitates the establishment of new techniques enabling molecular imaging of tumor vascular remodelling. The determination of tumor size as commonly used is not appropriate since the extended necrosis under anti-angiogenic therapy does not necessarily result in the reduction of tumor diameter. The basis for the molecular imaging of tumor blood vessels is the remodelling of the tumor vessels under anti-angiogenic therapy which obviously occurs at an early stage and seems to be a convincing parameter. Beside the enormous progress in this field during the last few years the resolution is still not high enough to evaluate the remodelling of the micro tumor vessels. New imaging approaches combining specific molecular markers for tumor vessels with the different imaging techniques are needed to overcome this issue as exemplarily discussed for prostate cancer in this review. Molecular contrast agents targeting the vasculature will allow clinicians the visualization of vascular remodelling processes taking place under anti-angiogenic therapy and improve tumor diagnosis and follow-up.