Christine Schröder

Myeloperoxidase attracts neutrophils by physical forces

Recruitment of polymorphonuclear neutrophils (PMNs) remains a paramount prerequisite in innate immune defense and a critical cofounder in inflammatory vascular disease. Neutrophil recruitment comprises a cascade of concerted events allowing for capture, adhesion and extravasation of the leukocyte. Whereas PMN rolling, binding, and diapedesis are well characterized, receptor-mediated processes, mechanisms attenuating the electrostatic repulsion between the negatively charged glycocalyx of leukocyte and endothelium remain poorly understood. We provide evidence for myeloperoxidase (MPO), an abundant PMN-derived heme protein, facilitating PMN recruitment by its positive surface charge. In vitro, MPO evoked highly directed PMN motility, which was solely dependent on electrostatic interactions with the leukocytes surface. In vivo, PMN recruitment was shown to be MPO-dependent in a model of hepatic ischemia and reperfusion, upon intraportal delivery of MPO and in the cremaster muscle exposed to local inflammation or to intraarterial MPO application. Given MPOs affinity to both the endothelial and the leukocytes surface, MPO evolves as a mediator of PMN recruitment because of its positive surface charge. This electrostatic MPO effect not only displays a so far unrecognized, catalysis-independent function of the enzyme, but also highlights a principal mechanism of PMN attraction driven by physical forces.

Adhesion of small cell lung cancer cells to E- and P-Selectin under physiological flow conditions: implications for metastasis formation

Haematogenous metastasis of small cell lung cancer (SCLC) is still a poorly understood process and represents the life threatening event in this malignancy. In particular, the rate-limiting step within the metastatic cascade is not yet clearly defined although, many findings indicate, that extravasation of circulating tumour cells is crucially important as most tumour cells within the circulation undergo apoptosis. If extravasation of SCLC tumour cells mimics leukocyte–endothelial interactions, SCLC cells should adhere to E- and P-selectins expressed on the luminal surface of activated endothelium. The adhesion to E- and P-selectin under physiological shear stress with regard to adhesive events, rolling behaviour and rolling velocity was determined in the human SCLC cell lines SW2, H69, H82, OH1 and OH3. OH1 SCLC cells adhered best to recombinant human (rh) E-selectin FC-chimeras and human lung endothelial cells (HPMEC), H82 SCLC cells adhered best to activated human umbilical vein endothelial cells (HUVEC) under physiological shear stress. As OH1 cells had also produced by far the highest number of spontaneous lung metastases when xenografted into pfp/rag2 mice in previous experiments our findings implicate that adhesion of SCLC cells to E-selectin is of paramount importance in SCLC metastasis formation.

The transcription factor Fra-2 promotes mammary tumour progression by changing the adhesive properties of breast cancer cells

The transcription factor Fra-2 (Fos-related antigen-2) has been implicated in invasion of breast cancer cells, but there is only sparse information about its role in clinical tumours. In the present study, we analysed Fra-2 mRNA expression in a cohort of 167 patients, and found significant correlations between high Fra-2 expression and nodal involvement or reduced disease-free survival. To get more information about the underlying mechanisms, we generated stably transfected MDA-MB231 breast cancer cells with increased Fra-2 expression. Compared with the controls, these clones did not differ in proliferation and motility, but had higher invasive potential. By global gene expression analysis and subsequent validation of selected genes, we identified a number of proteins involved in cell-cell or cell-matrix interactions that were up- or down-regulated in Fra-2 overexpressing cells, e.g. connexin 43, ICAM-1, L1-CAM, integrin beta 2, integrin beta 4, and integrin alpha 6. The association of Fra-2 overexpression and high ICAM-1 or L1-CAM levels could also be demonstrated in our clinical cohort of mammary tumours. In both MDA-MB231 and MCF7 cells, we found an increased attachment of Fra-2 transfectants to components of the extracellular matrix. In addition, we could show a striking increase in the number of rolling cells in flow-through assays using E-selectin coated capillaries, which might indicate a higher capacity of extravasation. In conclusion, our data obtained on breast cancer cell lines and clinical tissue samples suggest that overexpression of Fra-2 promotes breast cancer progression and metastasis by deregulation of genes involved in cell-cell and cell-ECM contacts.

Detection of activated leukocyte cell adhesion molecule in the serum of breast cancer patients and implications for prognosis.

Objective: Conflicting results have been reported about activated leukocyte cell adhesion molecule (ALCAM) expression in breast cancer and its prognostic value. Little is known about the role of ALCAM levels in the serum of breast cancer patients. Methods: We analyzed soluble ALCAM (sALCAM) levels in the serum of 157 primary breast cancer patients and 48 healthy women by ELISA. In addition, we determined ALCAM protein expression by Western blot analysis (n = 120) and mRNA expression by cDNA microarray analysis (n = 115) in the tumor tissue of corresponding patients. Results: sALCAM levels differed between patients and healthy controls (median 24.2 vs. 18.9 ng/ml, p < 0.001). We observed no correlation between serum levels and protein or mRNA expression in corresponding tumors (r < 0.1, p = n.s.). sALCAM levels were not correlated with histological type, grading, tumor stage, or patient age, but elevated sALCAM levels were associated with shorter disease-free survival (HR = 1.97, 95% CI 1.01–3.2, p = 0.043). Conclusions: Our results indicate that sALCAM can be detected in the serum of patients with primary breast cancer. Elevated serum levels might indicate more aggressive tumor behavior as they might be an independent factor for a worse prognosis in breast cancer patients.

Relevance of βGal-βGalNAc-containing glycans and the enzymes involved in their synthesis for invasion and survival in breast cancer patients

To study the influence of glycosylation on breast cancer progression by analyses on glycan, mRNA, and protein level. For detection of glycan structures, we performed lectin histochemistry with five lectins of different specificity (UEA-1, HPA, GNA, PNA, and PHA-L) on a tissue microarray with >400 breast cancer samples. For comparison, mRNA expression of glycosylation enzymes involved in the synthesis of HPA and PNA binding glycostructures (GALNT family members and C1GALT1) was analyzed in microarray data of 194 carcinomas. Additionally, C1GALT1 protein expression was analyzed by Western blot analysis in 106 tumors. Correlations with clinical and histological parameters including recurrence-free (RFS) and overall survival (OAS) were calculated. Positive binding of four lectins (HPA, GNA, PNA, and PHA-L) correlated significantly with parameters involved in tumor metastasis, namely lymphangiosis, vascular invasion, lymph node involvement, and presence of disseminated tumor cells in bone marrow. HPA and PNA binding also showed a negative prognostic impact in our cohort. Correspondingly, high expression of C1GALT1, GALNT1, GALNT8, or GALNT14 mRNA and C1GALT1 protein correlated significantly with shorter OAS. Notably, combined overexpression of C1GALT1/GALNT1 or C1GALT1/GALNT8 mRNA was associated with a significantly reduced OAS (HR 3.15 and 2.73) and RFS (HR 2.01 and 1.94), pointing to an additive influence of these enzymes. This prognostic impact retained significance in multivariate analysis including classical prognostic markers. Our data indicate that glycan structures containing βGal–βGalNAc residues and the enzymes involved in their synthesis play a role in breast cancer progression, at least partly by their promoting influence on haematogenic and lymphatic spread.

Influence of L1-CAM expression of breast cancer cells on adhesion to endothelial cells.

PurposeExpression of the adhesion molecule L1-CAM (L1) has been shown to correlate with early recurrence in breast cancer. Here, we investigated whether L1-CAM expression of breast cancer cells might influence adherence to human pulmonary microvascular endothelial cells (HPMEC) and thus promote metastasis.MethodsMDA-MB231-Fra2 breast cancer cells that express high levels of L1-CAM (L1high cells) were stably transfected to generate clones with strong L1-CAM downregulation. Adhesion to activated HPMEC was studied in dynamic cell flow and static assays. Potential binding partners on endothelial cells were identified by blocking experiments and adhesion assays after coating of the flow channels with recombinant proteins.ResultsAdhesion of L1high cells to activated HPMEC was significantly higher compared to L1low clones under flow conditions. Blocking experiments and adhesion assays with recombinant proteins identified activated leucocyte cell adhesion molecule (ALCAM) or L1 itself, but not ICAM-1, as potential binding partners on endothelial cells. E-selectin blocking antibodies strongly diminished the adherence of breast cancer cells irrespective of their L1-CAM expression.ConclusionsOur experiments indicate that L1-CAM expression on breast cancer cells can promote adherence to activated endothelial cells by binding to endothelial L1-CAM or ALCAM. This mechanism might lead to increased metastasis and a poor prognosis in L1-CAM-positive carcinomas in vivo. Therefore, L1-CAM might be a suitable therapeutic target in breast cancers with a high L1-CAM expression.

Prognostic relevance of ubiquitin C-terminal hydrolase L1 (UCH-L1) mRNA and protein expression in breast cancer patients

PurposeThe ubiquitin C-terminal hydrolase L1 (UCH-L1) belongs to the family of deubiquitinating enzymes. It is overexpressed in various tumour entities and associated with metastases formation in some solid tumours. However, only limited information about its role in breast cancer is available. The aim of this study was to examine the UCH-L1 expression in primary breast cancer and to determine its relevance as a potential prognostic marker.MethodsWe investigated both UCH-L1 mRNA expression in microarray data from 182 primary mammary carcinomas and UCH-L1 protein expression using a tissue microarray containing samples from 1,622 breast cancer patients.ResultsWith both methods, high UCH-L1 expression correlated significantly with negative oestrogen receptor and progesterone receptor status and advanced tumour stage. Moreover by Kaplan–Meier analysis, high UCH-L1 mRNA and protein expression correlated with a significantly shorter overall survival.ConclusionThe data of our study suggest that high levels of UCH-L1 expression indicate a more aggressive tumour behaviour and might represent a potential target in breast cancer treatment.

Expression and Prognostic Value of L1-CAM in Breast Cancer.

The L1 adhesion molecule (L1-CAM) is associated with impaired prognosis in many carcinomas. However, limited information about its expression in breast cancer tissue is available. Therefore, we carried out an analysis on L1 expression in primary breast cancers using a combination of Western blot, DNA-microarray analysis and immunohistochemistry. We observed L1 protein and mRNA overexpression in 14-15% of the carcinomas and this was confirmed by immunohistochemical staining. High L1 expression was associated with nodal involvement, high grading, human epidermal growth receptor 2 (Her-2), plasminogen activator inhibitor 1 (PAI-1) and vascular endothelial growth factor (VEGF) expression and a negative estrogen receptor (ER) status, but not with neuroendocrine markers. Moreover, patients with tumors showing high L1-CAM expression had a shorter disease-free and overall survival. Given the emerging functional role of L1 in promoting tumor cell migration, invasion, tumor growth and metastasis, our results suggest that L1 may have this function in breast cancer as well.