Status of estrogen receptor 1 (ESR1) gene in mastopathy predicts subsequent development of breast cancer.

Mastopathy is a common disease of the breast likely associated with elevated estrogen levels and a putative risk factor for breast cancer. The role of estrogen receptor alpha (ESR1) in mastopathy has not been investigated previously. Here, we investigated the prevalence of ESR1 gene amplification in mastopathy and its prediction for breast cancer. Paraffin-embedded tissues from 58 women with invasive breast cancer were analyzed. For all women, tissues with mastopathy taken at least 1.5 years before first diagnosis of breast cancer were available. Tissue from 46 women with mastopathy without a diagnosis of breast carcinoma in the observed time frame (12-18 years) was used as control. Fluorescence in situ hybridization analysis revealed that ESR1 was amplified in nine of 58 (15.5 %) breast cancers. All ESR1-amplified breast cancers were strongly positive for estrogen receptor with ER immunohistochemistry. Interestingly, in women with ESR1 amplification in breast cancer, the amplification was detectable in mastopathic tissues prior to the first diagnosis of breast cancer but was absent in tissues from women with mastopathy who did not develop breast cancer. Our study suggests that ESR1 gene amplification is an early event in breast pathology and might be a helpful predictive marker to identify patients at high risk of developing breast cancer.

Personal or first-degree family breast cancer history: which has higher impact on tumor detection and tumor size in breast cancer.

PURPOSE: A woman's risk of developing breast cancer (BC) is increased if she has a personal history (PH) or family history (FH) of the disease. We compared the impact of the two risk factors PH and FH on tumor detection and tumor size at diagnosis in a cohort of BC patients. METHODS: The study cohort comprised 1,037 invasive BC patients (≤70 years at diagnosis). From these, 92 patients (8.5%) had a positive PH and 151 patients (13.7%) had a positive first-degree FH. RESULTS: Compared to the tumors of patients without PH or FH, the lesions of patients who had a positive PH or a positive FH were more often found by radiologic breast examinations (RBE) (PH: 49.4%, FH: 43.4%, no PH/FH: 26.2%; both comparisons p < 0.001). In patients with a positive FH, the tumors were slightly less often found by RBE as in patients with a positive PH (p = 0.468). Patients with a positive PH or FH had smaller tumors compared with those without such a history (PH: 19.7 mm, FH: 19.6 mm, no PH/FH: 26.7 mm; p = 0.015/p < 0.001). The tumor sizes of patients with a positive PH were almost identical to those of patients with a positive FH (p = 0.999). CONCLUSIONS: In women with a positive FH or PH of BC, the increased awareness of BC risk led to the detection of smaller tumors compared to women who have not had this experience. However, comparison of the two risk factors showed that they had a similar impact on the RBE detection rate of BC lesions and that the tumor sizes were nearly identical.

Compliance and persistence of endocrine adjuvant breast cancer therapy.

This study evaluates compliance and persistence in adjuvant endocrine breast cancer (BC) therapy by clearly analyzing reasons of therapy cessation by differentiating clinical meaningful situations. In order to illuminate the complex field of personal motivation to therapy, a single institution study with a more individual-based approach might better be suited to provide a detailed case documentation than the more epidemiologic approach of large database studies. An unselected cohort of 698 patients (≤ 80 years) diagnosed with hormonal receptor-positive BC from 1997 to 2008 at the University Hospital Basel, Switzerland, was analyzed. The term "non-persistence" was exclusively used for patients where the discontinuation of endocrine therapy (ET) could have been modified by more intensive care and improved counseling (e.g., in women who lost faith/motivation to therapy or those who suffered from therapy-related side effects). These cases must be differentiated from cases where therapy cessation was inevitable (e.g., due to recurrent disease or severe intercurrent illness). Out of the 685 patients to whom ET was recommended, 42 patients (6.1%) refused and never began treatment (non-compliance). Women younger than 50 were more likely to be non-compliant (P < 0.001). 12.9% of the patients who started therapy were non-persistent to therapy. Patients who were treated by general practitioners tended to be non-persistent more often compared to those treated by oncologists (17.7% vs. 11.3%; P = 0.07). The aim of a non-persistence rate between 10 and 15% is realistic when patients are treated by specialized oncologists. Interventions are needed to support patients, particularly the younger ones, to comply with therapy. Efforts should be made to make sure that all physicians, above all general practitioners, who are involved in BC treatment, are provided with current knowledge as to guarantee an optimal patient management.

Eligibility, compliance and persistence of extended adjuvant endocrine therapy for breast cancer.

BACKGROUND: Extended therapy (ET) beyond the standard five years of tamoxifen-containing treatment is a widely discussed therapy option in adjuvant endocrine breast cancer (BC) therapy which might offer an opportunity for further protection against late relapses. In this study we evaluated eligibility, compliance and persistence of extended adjuvant endocrine BC therapy. PATIENTS AND METHODS: Data concerning all BC patients (≤75 years) who initiated endocrine adjuvant therapy between 1999 and 2005 (n = 286) was analyzed. RESULTS: One hundred and thirty-eight patients were valid candidates for an ET according current guidelines; this represents 48.3% of the individuals who started endocrine therapy five years ago. Of these, 89 (64.5%) received a corresponding offer/recommendation by their treating physicians. Advanced age (p = 0.002), favorable disease stage (p = 0.011), and follow-up at a general practitioner (p < 0.001) were significant factors where a recommendation for an ET was not made. Of the 89 patients who were offered an ET, 64 followed this proposal (compliance: 84.7%). Eighteen patients (28.1%) were non-persistent to the ET; therapy-related adverse effects were the main reason for discontinuation. Sixteen patients received an ET beyond current guidelines (tamoxifen or an aromatase inhibitor alone was given longer than five years); this represents 11.0% of all patients who completed five years of endocrine therapy. CONCLUSIONS: Only a minority of the patients who started an endocrine therapy were actually eligible for an ET. Patients who were offered/recommended an ET had a high rate of compliance and persistence. Efforts should be made to make sure that all physicians, above all general practitioners, who are involved in the treatment of BC patients, are provided with current therapy guidelines as to guarantee an optimal patient management.

Young women with breast cancer: how many are actually candidates for fertility preservation?

PURPOSE: There are no data regarding the actual need for fertility preservation (FP) in breast cancer (BC) patients. Our study provides a practical needs assessment for reproductive medicine by analyzing an unselected cohort of young BC patients. This assessment considers oncological factors as well as the patient's obstetrical and gynecological history and reproductive outcome after BC diagnosis. We aimed to identify how many patients are actually potential candidates for FP and how many patients might consequently use their cryopreserved gametes to achieve pregnancy. METHODS: Based on a prospective BC database, we analyzed all patients who were ≤40 years at initial diagnosis (time period of diagnosis: 1990-2007; n=100; 7.7% of the entire BC cohort; median age: 35.9 years). RESULTS: Using an algorithm of exclusion criteria considering disease-specific, therapy-specific and family history characteristics, 36 patients who received chemotherapy were identified as potential "classical" candidates for FP. After 5 years, 22 women were identified as potential candidates for using their cryopreserved gametes to achieve pregnancy; the majority of these patients were childless (n=16, 72.7%) and in their late reproductive years (n=12, 54.5%). CONCLUSIONS: Our study demonstrates that in a cohort of young BC patients only a minority of women are candidates for FP. Young BC patients who wish to have children in the future usually carry risk factors both from oncological and reproductive medicine perspective. Due to this high-risk profile, the rarity of BC in young age and the limited number of patients who might actually have opted for FP, these women must be offered timely and multidisciplinary counseling in highly specialized centers.

Drug switch because of treatment-related adverse side effects in endocrine adjuvant breast cancer therapy: how often and how often does it work?

Therapy-related adverse side effects are a main reason for non-persistence to adjuvant endocrine breast cancer therapy. This study reports frequency of drug-related adverse side effects that were so severe that a modification of the therapy was necessary. We evaluated how many patients discontinued adjuvant endocrine therapy because of these side effects (non-persistence). Last, we analyzed how often a drug switch was undertaken for this reason and how often this measure led to the patient successfully continuing their endocrine therapy. Data concerning all postmenopausal breast cancer patients (≤ 80 years), who initiated endocrine adjuvant therapy between 1998 and 2008 in a Swiss breast center (n = 400), were analyzed. Out of these 400 women, 37 (9.3%) were defined as being non-persistent to the therapy; out of these, 24 (64.9%) because of therapy-related side effects. About 78 patients (19.5%) suffered from severe therapy-related side effects that made a modification of therapy necessary. Out of these 78 cases, 14 patients (17.9%) stopped the therapy without attempting a drug switch (non-persistence). In 64 patients (82.1%; 16% of all women who started endocrine therapy), a drug switch was undertaken. Out of these 64 cases, in 52 cases (81.3%) endocrine therapy was completed after therapy modification. Patients who reported one major adverse effect were more likely to continue the endocrine therapy after a drug switch (P = 0.048) compared with those who suffered from at least two different side effects. In 10 of the 64 cases (15.6%), modification of the therapy was not successful and the patients stopped the treatment prematurely (non-persistence) because of ongoing side effects. In cases when therapy-related side effects occur, a drug switch is a promising step to further improve persistence and, by doing so, the outcome of breast cancer patients.

Success and failure of primary medical, nonoperative management in breast cancer.

BACKGROUND: Nonoperative but systemic therapy as first-line management is offered to some patients with breast cancer (BC) who have assumed limited life expectancy, such as older women or those who have distant metastases at initial presentation. We evaluated rates of and predicting factors for success and failure of this therapy approach. METHODS: Seventy-five patients who were initially treated only systemically, and cases in which local control while avoiding surgery was the intended long-term therapy goal were analyzed. Additionally, two stage-dependent subgroups were distinguished (A: stage I-III, n = 31; B: stage IV, n = 44). Failure of therapy was defined as when secondary surgery had to be performed due to locoregional progression or in case of no surgery when severe locoregional clinical signs/symptoms were observed during the further course. RESULTS: Patients in group A were older than those in group B (81 vs. 67.5 years; P < 0.001) and showed an increased survival (5-year rates: 40.2% vs. 24.3%). In 24 patients of the entire cohort (32%), secondary surgery had to be performed; surgery was performed more often in group A (58.1% vs. 13.6%). In the cases in which no surgery was performed (n = 51), 11 women (21.6%) suffered from severe locoregional symptoms in the palliative situation (A: n = 1; B: n = 10). Although the presence of stage IV was a significant factor for therapy success (odds ratio (OR), 2.59; 95% confidence interval (CI), 0.95-7.05; P = 0.039), skin involvement was associated with failure of therapy (OR, 3.57; 95% CI, 1.16-11.11; P = 0.031). CONCLUSIONS: Nonoperative treatment may be offered to selected patients with BC who have assumed limited life expectancy. These women must be openly informed that this approach is not successful in nearly half of the cases.

Eligibility, compliance and persistence of sequential therapy with aromatase inhibitors following 2-3 years of tamoxifen in endocrine adjuvant breast cancer therapy.

OBJECTIVE: This study evaluated the eligibility, compliance and persistence of sequential therapy, i.e. a switch to an aromatase inhibitor (AI) following 2-3 years of tamoxifen, in adjuvant endocrine breast cancer (BC) treatment. METHODS: Data concerning 388 BC patients (age ≤70 years) who started endocrine adjuvant therapy between 1998 and 2008 were analyzed. RESULTS: From the 263 patients who started therapy with tamoxifen, 167 (63.5%) were eligible for a sequential therapy. Fifty-nine patients (35.3%) were offered a switch by their physicians; women who had their follow-up at oncological units received the offer more often when compared to those treated by general practitioners (p < 0.001). Out of these 59 patients, 50 followed the proposal (compliance 84.7%). Of those who agreed to a sequential therapy, 2 (4%) were non-persistent to endocrine therapy; in 9 cases (18.0%), a re-switch to tamoxifen was done due to AI-related adverse side effects. CONCLUSIONS: Only a minority of the patients who started an endocrine adjuvant BC therapy was eligible for sequential therapy. Patients who underwent a switch had a high rate of persistence. Efforts should be made to make sure that all physicians, above all general practitioners, who are involved in the treatment of BC patients, are provided with current therapy guidelines.

A novel population of repair cells identified in the stroma of the human cornea.

The transmembrane protein CD133 is expressed on somatic stem cells of various adult human tissues. To investigate whether human corneal stroma also contains CD133-expressing cells and to analyze their functional features, stromal cells were isolated by collagenase digestion, immunophenotyped, and transferred to different culture systems to determine their stem cell properties as well as their differentiation potentials. For comparison, the embryonic keratocyte cell line EK1.Br, the dermal stromal cell line NHDF, and stromal cells of diseased corneas were studied. On average, 5.3% of the normal stromal cells expressed the stem cell marker CD133 and 3.6% co-expressed CD34. Expression of CD133 but not CD34 was also demonstrated for EK1.Br cells, whereas NHDF cells were negative for both markers. Further analysis of CD133(+) normal corneal cells revealed that a significant proportion displayed a monocytic phenotype with co-expression of CD45 and CD14. In diseased corneas, up to 26.8% of the stromal cells showed expression of CD133, and virtually all CD133(+) cells co-expressed CD14 but not CD45. Moreover, using a standard clonogenic assay, normal stromal cells had the capacity to form colonies of the macrophage lineage. These colonies could be further differentiated into lumican-expressing keratocytes. Our data suggest that the human corneal stroma harbors CD133(+) monocytic progenitor cells, which possess the potential to differentiate into the fibrocytic lineage. Thus, CD133(+) /CD45(+) /CD14(+) cells might represent stromal repair cells that differentiate into keratocytes via a CD133(+)/CD45()/CD14(+) intermediate stage. The findings from our study may shed new light on regenerative processes of the human corneal stroma.

Potential implications of vascular wall resident endothelial progenitor cells.

A rapidly increasing body of data suggests an essential role of endothelial progenitor cells (EPCs) in vascular regeneration, formation of new vessels in cardiovascular diseases and also in tumor vasculogenesis. Moreover, recent data obtained from clinical studies with anti-angiogenic drugs in tumor therapy or with pro-angiogenic stimuli in ischemic disorders implicate a predictive role of the number of EPCs circulating in the peripheral blood in monitoring of these diseases. However, there is still some controversial data regarding the relevance of the EPCs in vascular formation depending on models used and diseases studied. One of the essential prerequisites for a better understanding of the whole contribution of EPCs to vascular formation in adult, a process called postnatal vasculogenesis, is to identify their exact sources. We could recently discover the existence of EPCs in a distinct zone of the vascular wall of large and middle sized adult blood vessels and showed that these cells are capable to differentiate into mature endothelial cells, to form capillary sprouts in arterial ring assay and to build vasa vasorum-like structures within the vascular wall. They also can be mobilized very rapidly from the vascular wall by tumor cells. This review will discuss the functional implications of these vascular wall resident endothelial progenitor cells (VW-EPCs) in relation to those of EPCs circulating in peripheral blood or derived from the bone marrow in cardiovascular and neoplastic diseases.

Significance of vascular stabilization for tumor growth and metastasis.

This mini review highlights the role of vascular stabilization which is apparently mediated by factors belonging to both the pro- and anti-angiogenic group. Knowingly angiopoietin-1 has pro-angiogenic properties while endostatin acts anti-angiogenic. But both factors suppress tumor growth in experimental tumor models. The crossing points of mechanisms of their action are the parameters vascular stabilization and vascular permeability, which are of high importance not only for tumor vascularization, but also for tissue vascularization in general. Both angiopoietin-1 and endostatin reduce the vascular permeability, but promote vascular stabilization. Vascular stabilization is significantly increased under experimental treatment of tumors with angiogenesis inhibitors such as endostatin. It inhibits tumor growth and probably tumor metastasis. The understanding of temporal and spatial sequences of vascular stabilization is an important challenge for scientists working on tumor vascularization and anti-angiogenic tumor therapy.

Brachyury expression predicts poor prognosis at early stages of colorectal cancer.

Although survival rates of colon cancer patients diagnosed at an early stage (T1-2N0M0; Dukes A) vary considerably according to the studies cited, several studies indicate development of distant metastases already occurring in a considerable percentage of these patients leading to the death of the patients. This particular high risk group cannot be identified properly as no marker exists to identify these patients. As the Wnt/Win pathway plays a crucial role in metastasis formation in colorectal carcinoma, we analysed whether the transcription factor brachyury critically involved in this pathway may predict metastasis formation in these patients. The expression of brachyury-homologous (T) was immunohistochemically analysed in 748 patients and the data were correlated with classical and newer prognostic markers in colorectal cancer. Early stages colorectal cancer patients (T1-2N0M0, Dukes A) showed a significantly decreased survival when brachyury was expressed in the tumour tissue while no correlation was observed in later tumour stages. Hence a subset of colorectal cancers exists in which the ability to metastasise is already present at early stages of tumour growth and this high risk group can now be detected by immunohistochemistry.

Epithelial versus endothelial CEACAM1 expression and angiogenesis in epididymal adenomatoid tumor.

BACKGROUND/AIM: To study the expression of the pro-angiogenic factor carcinoembryonic antigen-related cell adhesion molecule-1 (CEACAM1) in epididymal adeno-matoid tumor tissue, a very rare benign neoplasia, in relation to its vascularization. MATERIALS AND METHODS: Immunohistochemistry for CEACAM1 and for both endothelial markers CD31 and CD34 was performed in normal human epididymal and epididymal adenomatoid tumor tissue. The vessel density was calculated in four tumor regions with different degrees of vascularization in comparison to the vascularization of the normal epididymal tissue. RESULTS: CEACAM1 was found in normal epididymal epithelium, while the epithelium of tumor glands was mostly negative. Only few blood vessels and lymphatics in adenomatoid tumor tissue expressed CEACAM1. The assessment of vascularization revealed either equal or a significantly lower vessel density in some adenomatoid tumor regions in comparison to normal epididymal tissue. DISCUSSION: These data demonstrate that despite its epithelial down-regulation, CEACAM1 is not present in the majority of adenomatoid tumor blood vessels, which might be related to the lower angiogenic activity and benign behaviour of this tumor.

High level of endostatin in epididymal epithelium: protection against primary malignancies in this organ?

Rete testis and epididymis are rare locations for primary tumors or metastasis. Assuming that this may be related to expression level of angiogenic inhibitors, we focused our study on the expression pattern of collagen 18/endostatin. In situ hybridization and immunohistochemistry for collagen 18 and endostatin were carried out on sections of human rete testis and epididymis as well as on epididymal adenoma and human testicular tissue with or without carcinoma in situ (CIS). In situ hybridization revealed strong expression of collagen 18 mRNA in rete testis, efferent ducts and epididymal duct. Immunostaining showed collagen 18 in epithelium and basement membrane as well as in blood vessels of rete testis. Further, in both efferent ducts and epididymal duct, collagen 18 was mainly localized in the basement membrane of these ducts and of the blood vessel wall. Endostatin immunostaining was localized in the epithelium of rete testis, efferent ducts and epididymal duct. This pattern of endostatin staining was absent in epididymal adenoma tissue while tumor associated blood vessels exhibited strong endostatin staining. No endostatin staining was detectable in normal germinal epithelium and CIS cells while Leydig cells exhibited strong endostatin staining. High endostatin expression in epididymis may protect this organ against tumor development. Gene therapeutic strategies providing high expression of endostatin in normal epithelia may be useful to prevent tumor development.

Endothelial and hematopoietic progenitor cells (EPCs and HPCs): hand in hand fate determining partners for cancer cells.

Tumor growth and metastasis need new vessel formation by angiogenesis provided by mature endothelial cells and postnatal vasculogenesis provided by endothelial progenitor cells (EPCs). Emerging data suggest a coordinated interaction between EPCs and hematopoietic progenitor cells (HPCs) in these processes. The complexity of the mechanisms governing the new vessel formation by postnatal vasculogenesis has increased by new evidence that not only bone marrow derived EPCs and HPCs seem to be involved in this process but also local progenitors residing within the vascular wall are mobilized and activated to new vessel formation by tumor cells. This review attempts to bring these systemic and local players of postnatal vasculogenesis together and to highlight their role in tumor growth and mestastasis.

Zone-specific remodeling of tumor blood vessels affects tumor growth.

BACKGROUND: Chaotic organization, abnormal leakiness, and structural instability are characteristics of tumor vessels. However, morphologic events of vascular remodeling in relation to tumor growth are not sufficiently studied yet. METHODS: By using the rat rhabdomyosarcoma tumor model vascular morphogenesis was studied by light and electron microscopy and immunohistochemistry in relation to tumor regions such as tumor surrounding (TSZ), marginal (TMZ), intermediate (TIZ), and center (TCZ) zones. RESULTS: The analyses revealed that blood vessels of TSZ display a regular ultrastructure, whereas blood vessels of TMZ showed a chaotic organization and unstable structure with a diffuse or even lacking basal lamina, and missing or irregular assembled periendothelial cells. In contrast, blood vessels of TIZ and TCZ exhibited a more or less stabilized vessel structure with increased diameter. Correspondingly, normal assembly of alpha-smooth-muscle-actin (alpha-SMA)-positive cells into the vessel wall was observed in blood vessels of TSZ, TIZ, and TCZ. Also, Ang1 immunostaining was strongest in large vessels of TIZ and TCZ, whereas Ang2 staining was prominent in small vessels of TIZ. Tie2 staining was detectable in small and large vessels of all tumor zones. Immunostaining for alpha(v)beta(3)-integrin was strongest in small vessels of TMZ, whereas large vessels of TIZ and TCZ were almost negative. CONCLUSIONS: The results indicate a zone-specific remodeling of tumor blood vessels by stabilization of vessels in TIZ and TCZ, whereas small vessels of these zones obviously undergo regression leading to tumor necrosis. Thus, a better understanding of vascular remodeling and stabilization in tumors would enable new strategies in tumor therapy and imaging.

Lymphatic reprogramming of microvascular endothelial cells by CEA-related cell adhesion molecule-1 via interaction with VEGFR-3 and Prox1.

Here, we demonstrate that carcinoembryonic antigen-related cell adhesion molecule-1 (CEACAM1) is expressed and co-localized with podoplanin in lymphatic endothelial cells (LECs) of tumor but not of normal tissue. CEACAM1 overexpression in human dermal microvascular endothelial cells (HDMECs) results in a significant increase of podoplanin-positive cells in fluorescence-activated cell sorting analyses, while such effects are not observed in CEACAM1 overexpressing human umbilical vein endothelial cell (HUVECs). This effect of CEACAM1 is ceased when HDMECs are transfected with CEACAM1/y- missing the tyrosine residues in its cytoplasmic domain. CEACAM1 overexpression in HDMECs leads to an up-regulation of vascular endothelial growth factor C, -D (VEGF-C, -D) and their receptor vascular endothelial growth factor receptor 3 (VEGFR-3) at mRNA and protein levels. HDMECs transfected with CEACAM1 but not those with CEACAM1/y- show enhanced expression of the lymphatic markers Prox1, podoplanin, and LYVE-1. Furthermore, Prox1 silencing in HDMECs via small interfering RNA blocks the CEACAM1-induced increase of VEGFR-3 expression. Number and network of endothelial tubes induced by VEGF-C and -D are enhanced in CEACAM1-overexpressing HDMECs. Moreover, VEGF-A treatment of CEACAM1-silenced HDMECs restores their survival but not that with VEGF-C and VEGF-D. These data imply that the interaction of CEACAM1 with Prox1 and VEGFR-3 plays a crucial role in tumor lymphangiogenesis and reprogramming of vascular endothelial cells to LECs. CEACAM1-induced signaling effects appear to be dependent on the presence of tyrosine residues in the CEACAM1 cytoplasmic domain.

Vascular wall resident progenitor cells: a source for postnatal vasculogenesis.

Here, we report the existence of endothelial precursor (EPC) and stem cells in a distinct zone of the vascular wall that are capable to differentiate into mature endothelial cells, hematopoietic and local immune cells, such as macrophages. This zone has been identified to be localized between smooth muscle and adventitial layer of human adult vascular wall. It predominantly contains CD34-positive (+) but CD31-negative (-) cells, which also express VEGFR2 and TIE2. Only few cells in this zone of the vascular wall are positive for CD45. In a ring assay using the fragments of human internal thoracic artery (HITA), we show here that the CD34+ cells of the HITA-wall form capillary sprouts ex vivo and are apparently recruited for capillary formation by tumor cells. New vessels formed by these vascular wall resident EPCs express markers for angiogenically activated endothelial cells, such as CEACAM1, and also for mature endothelial cells, such as VE-cadherin or occludin. Vascular wall areas containing EPCs are found in large and middle sized arteries and veins of all organs studied here. These data suggest the existence of a ;vasculogenic zone' in the wall of adult human blood vessels, which may serve as a source for progenitor cells for postnatal vasculogenesis, contributing to tumor vascularization and local immune response.

Pro-angiogenic signaling by the endothelial presence of CEACAM1.

Here, we demonstrate the expression of carcinoembryonic antigen-related cell adhesion molecule-1 (CEACAM1) in angiogenic sprouts but not in large mother blood vessels within tumor tissue. Correspondingly, only human microvascular endothelial cells involved in in vitro tube formation exhibit CEACAM1. CEACAM1-overexpressing versus CEACAM1-silenced human microvascular endothelial cells were used in migration and tube formation assays. CEACAM1-overexpressing microvascular endothelial cells showed prolonged survival and increased tube formation when they were stimulated with vascular endothelial growth factor (VEGF), whereas CEACAM1 silencing via small interfering RNA blocks these effects. Gene array and LightCycler analyses show an up-regulation of angiogenic factors such as VEGF, VEGF receptor 2, angiopoietin-1, angiopoietin-2, tie-2, angiogenin, and interleukin-8 but a down-regulation of collagen XVIII/endostatin and Tie-1 in CEACAM1-overexpressing microvascular endothelial cells. Western blot analyses confirm these results for VEGF and endostatin at the protein level. These results suggest that constitutive expression of CEACAM1 in microvascular endothelial cells switches them to an angiogenic phenotype, whereas CEACAM1 silencing apparently abrogates the VEGF-induced morphogenetic effects during capillary formation. Thus, strategies targeting the endothelial up-regulation of CEACAM1 might be promising for antiangiogenic tumor therapy.