Involvement of alpha 1-2-fucosyltransferase I (FUT1) and surface-expressed Lewis(y) (CD174) in first endothelial cell-cell contacts during angiogenesis

During the initiation of tumor associated angiogenesis endothelial cells migrate, adhere to extracellular matrix and form cell-cell contacts. Humoral factors of malignant cells conduct this process. We investigated whether cell surface expression of the carbohydrate blood group determinant Lewis(y) (CD174) and its precursor structure H2 (CD173) on endothelial cells is influenced by soluble factors of tumor cells. Using a bone marrow derived endothelial cell line we observed an enhanced expression of CD173/CD174 and transcription of FUT1, the key enzyme for their synthesis, after treatment with tumor necrosis factor-alpha (TNF-alpha) or conditioned supernatants of the leukemia cell line KG1a. CD173/CD174 are concentrated on pseudopodial extensions responsible for initial contacts between endothelial cells. Endothelial migration induced by TNF-alpha could be diminished by antibodies to CD174 as well as by siRNA induced downmodulation of FUT1 transcription. Endothelial FUT1-siRNA-transfectants displayed impaired in vitro angiogenesis when cultivated on extracellular matrix and in spheroid assays. In vivo upregulation of CD174 expression was observed immunocytologically in capillaries of tumor-infiltrated tissue. Together, our observations point to a tumor induced transcription of endothelial FUT1 and consequently an enhanced expression of CD174 which is involved in migration and early cell-cell contacts during tumor associated angiogenesis.

The aorta-gonad-mesonephros-derived stroma cell line DAS104-4 induces differentiation of leukemic cells

While critical steps in the regulation of leukemia cell development have been intensively studied in recent years, less is known about the interactions of leukemic cells with their stroma. Previously, we have shown that human acute myeloid leukemia (AML) cells differentiate upon injection into murine blastocysts. We here describe that human AML Kasumi-1 cells, cocultured with murine aorta-gonad-mesonephros (AGM) region-derived DAS104-4 stromal cells, decrease proliferation and colony formation efficiency; and up-regulate myelo-monocytic cell surface markers. Gene expression analysis showed decreased transcription of the AML1-ETO fusion gene and increased transcription of p16 (INK4A), p21 (WAF1) and C/EBPalpha genes. Coculture can induce myeloid differentiation also in patient-derived AML cells. Our findings strengthen the notion that the embryonic milieu can regulate the proliferation and differentiation of leukemic cells.

[Merkel cell carcinoma--clinically often misjudged]

Merkel cell carcinoma is a rare, rapidly growing, highly malignant dermal tumor which occurs preferentially on light-exposed skin in advanced age. The course of the disease is frequently characterized by the occurrence of lymph node metastases and local recurrences, even in the first year after removal of the primary tumour. The five-year overall survival rate is only about 65 %, despite rigorous therapy. The histological pattern is characterized by trabecular strands of small, uniform cells with large basophilic nuclei and typical neuroendocrine granules. The diagnosis is confirmed immunohistochemically by neuroendocrine and epithelial markers. The excision of the primary tumor is regarded as first-line therapy. Adjuvant radiatiotherapy is almost always indicated and should also include lymph node drainage. In the stage of nodal disease, a combination of excision and radiotherapy is recommended. Adjuvant chemotherapy can be applied in this stage, as in small-cell bronchial carcinoma. The prognostic advantage has, however, not been proven. Despite good response to radiatiotherapy and chemotherapy, with at least prolonged recurrence-free intervals, Merkel cell carcinoma is rarely curable at the distant metastasizing stage. Individually defined, aggressive treatment,including radiatiotherapy, may in future considerably improve the prognosis, especially in the early stages of the disease.

One-step production of polymeric microtubes by co-electrospinning

Herein we demonstrate the ability to fabricate polymeric microtubes with an inner diameter of approximately 3 microm through co-electrospinning of core and shell polymeric solutions. The mechanism by which the core/shell structure is transformed into hollow fibers (microtubes) is primarily based on the evaporation of the core solution through the shell and is described here in detail. Additionally, we present the filling of these microtubes, thus demonstrating their possible use in microfluidics. We also report the incorporation of a protein (green fluorescent protein) within such fibers, which is of interest for sensorics.

Poly(ethylene carbonate): A thermoelastic and biodegradable biomaterial for drug eluting stent coatings?

A first feasibility study exploring the utility of poly(ethylene carbonate) (PEC) as coating material for drug eluting stents under in vitro conditions is reported. PEC (Mw 242 kDa, Mw/Mn=1.90) was found to be an amorphous polymer with thermoelastic properties. Tensile testing revealed a stress to strain failure of more than 600%. These properties are thought to be advantageous for expanding coated stents. In vitro cytotoxicity tests showed excellent cytocompatibility of PEC. Based on these findings, a new stenting concept was suggested, pre-coating a bare-metal stent with PPX-N as non-biodegradable basis and applying a secondary PEC coating using an airbrush method. After manual expansion, no delamination or destruction of the coating could be observed using scanning electron microscopy. The surface degradation-controlled release mechanism of PEC may provide the basis for "on demand" drug eluting stent coatings, releasing an incorporated drug predominantly at an inflamed implantation site upon direct contact with superoxide-releasing macrophages. As a release model, metal plates of a defined size and area were coated under the same conditions as the stents with PEC containing radiolabelled paclitaxel. An alkaline KO(2-) solution served as a superoxide source. Within 12 h, 100% of the incorporated paclitaxel was released, while only 20% of the drug was released in non-superoxide releasing control buffer within 3 weeks.

[Heat shock protein 90 alpha und beta are overexpressed in multiple myeloma cells and critically contribute to survival]

HSP90's are overexpressed in different cancer types and they probably are required to sustain aberrant signalling in malignant cells. Recently, pharmacological inhibition of HSP90 was found to suppress growth of myeloma cell lines and in primary myeloma cells. Therefore, we wanted to investigate the role of HSP90alpha and HSP90beta in the pathogenesis of malignant myeloma (MM) in more detail. Immunohistochemistry was employed to examine the expression of HSP90alpha and HSP90beta in MM. The importance of HSP90 for survival of MM -cells was investigated by SiRNA-mediated knockdown of HSP90 and blockade of the IL-6R/STAT3 and the MAPK signaling pathways in vitro. HSP90alpha and HSP90beta were overexpressed in majority of investigated MM cases, but not in MGUS or in normal plasma cells. SiRNA-mediated knockdown of HSP90 or treatment with the novel HSP90 inhibitor 17-DMAG attenuated the levels of STAT3 and phospho-ERK and decreased the viability of MM cells. The knockdown of HSP90alpha was sufficient to induce apoptosis. This effect was strongly increased when both HSP90s were targeted, indicating a cooperation of both. HSP90 critically contributes to myeloma survival in the context of its microenvironment and therefore strengthen the potential value of HSP90 as a therapeutic target.

CARMA1 and chromosomal translocations in extranodal marginal zone B-cell lymphomas of MALT type or diffuse large B-cell lymphomas

We analyzed the configuration of the CARMA1 gene, encoding a protein that closely interacts with BCL10 and MALT1, in a series of 120 extranodal marginal zone B-cell lymphomas of MALT-type and 35 diffuse large B-cell lymphomas. Our study suggests that CARMA1 is not targeted by chromosomal translocations in these lymphoma entities.

STAT3 and MAPK signaling maintain overexpression of heat shock proteins 90alpha and beta in multiple myeloma cells, which critically contribute to tumor-cell survival

The combined blockade of the IL-6R/STAT3 and the MAPK signaling pathways has been shown to inhibit bone marrow microenvironment (BMM)-mediated survival of multiple myeloma (MM) cells. Here, we identify the molecular chaperones heat shock proteins (Hsp) 90alpha and beta as target genes of both pathways. The siRNA-mediated knockdown of Hsp90 or treatment with the novel Hsp90 inhibitor 17-DMAG attenuated the levels of STAT3 and phospho-ERK and decreased the viability of MM cells. Although knockdown of Hsp90beta-unlike knockdown of Hsp90alpha-was sufficient to induce apoptosis, this effect was strongly increased when both Hsp90s were targeted, indicating a cooperation of both. Given the importance of the BMM for drug resistance and MM-cell survival, apoptosis induced by Hsp90 inhibition was not mitigated in the presence of bone marrow stromal cells, osteoclasts, or endothelial cells. These observations suggest that a positive feedback loop consisting of Hsp90alpha/beta and major signaling pathways supports the survival of MM cells. Finally, in situ overexpression of both Hsp90 proteins was observed in most MMs but not in monoclonal gammopathy of undetermined significance (MGUS) or in normal plasma cells. Our results underpin a role for Hsp90alpha and beta in MM pathogenesis.

Technical and clinical success of infrarenal endovascular abdominal aortic aneurysm repair: A 10-year single-center experience

OBJECTIVE

The aim of our retrospective study was to review our single-center experience with aortic abdominal aneurysm (AAA) repair retrospectively.

MATERIAL AND METHODS

From 1995 to 2005, 70 consecutive patients affected by AAA were treated by endovascular stent-graft repair. Mean follow-up was 23.9 months. Follow-up investigations were performed at 6 and 12 months and yearly thereafter. Five different stent-graft designs were compared to each other. Primary technical success (PTS), assisted primary technical success (APTS), primary clinical success (PCS) and secondary clinical success (SCS) were evaluated.

RESULTS

All over PTS was achieved in 94.3%, APTS in 97.1%, PCS in 61.4%, APCS in 64.3% and SCS in 70%. There were 3 type I endoleaks, 25 type II endoleaks, 4 type III endoleaks, 8 limb problems, 5 conversions to open surgery, 10 aneurysm sac expansions and 14 device migrations. Patients with newer generation devices showed better results than patients with first generation prosthesis. In addition results were better for grafts with suprarenal fixation (versus infrarenal fixation) and grafts with barbs and hooks (versus grafts without barbs and hooks). Patients with bad anatomic preconditions showed a higher complication rate.

CONCLUSION

Contrary to first generation products, new stent-graft designs show acceptable technical and clinical results in endovascular AAA aneurysm repair. However, this therapy still should be reserved only for patients with significant comorbities and suitable anatomic conditions.

Biohybrid nanosystems with polymer nanofibers and nanotubes

Advanced techniques for the preparation of nanofibers, core shell fibers, hollow fibers, and rods and tubes from natural and synthetic polymers with diameters down to a few nanometers have recently been established. These techniques, among them electro- and co-electrospinning and specific template methods, allow the incorporation not only of semiconductor or catalytic nanoparticles or chromophores but also enzymes, proteins, microorganism, etc., directly during the preparation process into these nanostructures in a very gentle way. One particular advantage is that biological objects such as, for instance, proteins can be immobilized in a fluid environment within these polymer-based nano-objects in such a way that they keep their native conformation and the corresponding functions. The range of applications of such biohybrid nanosystems is extremely broad, for instance, in the areas of biosensorics, catalysis, drug delivery, or optoelectronics.

Influence of antigen on the development of MALT lymphoma

Mucosa-associated lymphoid tissue (MALT) B-cell lymphomas develop in the context of autoimmune or chronic inflammations like Helicobacter pylori-induced gastritis. Remission of most gastric MALT lymphomas after eradication of H pylori links tumor cell proliferation to antigen-induced inflammation and the need for antigenic contact. Furthermore, the tumor cells correspond to antigen-activated memory B cells. To investigate the reactivity of the tumor immunoglobulins we employed in vitro-generated antibodies identical to those produced by MALT lymphoma cells. The immunoglobulin rearrangements of 7 MALT lymphomas were amplified, cloned, and expressed as single-chain fragment variable (scFv) antibodies. Antigen specificity of these 7 scFvs was analyzed by immunohistochemical staining of various normal, reactive, and malignant human tissues. Also, an expression library comprising approximately 30,000 proteins from human fetal brains (protein filter) and a peptide library were screened. One scFv stained a subpopulation of tonsillar plasma cells in immunohistochemical studies. On protein filters this scFv recognized the plasma cell-related protein Ufc1. Peptide library screening identified 9 peptides as binding partners of an additional scFv. The majority of MALT lymphoma immunoglobulins studied, however, showed no reactivity against antigens, indicating that the tumor immunoglobulins do not play a significant role in stimulation and proliferation of the MALT lymphoma tumor cells.

Evidence of abortive plasma cell differentiation in Hodgkin and Reed-Sternberg cells of classical Hodgkin lymphoma

Hodgkin and Reed-Sternberg (HRS) cells of classical Hodgkin lymphoma (cHL) show genotypic features of germinal centre-derived B-cells in most cases. Nevertheless, these cells typically lack expression of B-cell antigens. Previous studies have suggested that plasma cell differentiation may occur in HRS cells and that this may account for the down-regulation of B-cell antigens. However, these results are controversial. We have addressed this question using immunohistochemistry and a panel of antibodies directed against antigens which are differentially expressed during terminal B-cell differentiation. Pax-5, a transcription factor required for B-lineage commitment, and IRF4/Mum1, which is physiologically expressed in germinal centre cells and plasma cells, were consistently detectable in HRS cells. Bcl-6, a transcription factor expressed in germinal centre B-cells, was present in HRS cells of approximately 25% of cHL cases. Expression of the B-lymphocyte-induced maturation protein-1 (Blimp-1), a key regulator of plasma cell differentiation, was observed in HRS cells of 23% of cHL cases. In these cases, Blimp-1 expression was restricted to a small proportion of HRS cells. HRS cells were consistently negative for the plasma cell marker CD138. These results suggest that plasma cell differentiation may be initiated in a small subset of HRS cells but remains abortive. Thus, terminal differentiation is unlikely to explain the lack of B-cell antigen expression in HRS cells.

Differential expression of activation-induced cytidine deaminase (AID) in nodular lymphocyte-predominant and classical Hodgkin lymphoma

Activation-induced cytidine deaminase (AID) is indispensable for class switch recombination and somatic hypermutation of immunoglobulin genes. Expression of AID has been detected in germinal centre centroblasts and in lymphomas derived from germinal centre cells. However, in situ studies of AID expression have until now been hampered by a lack of antibodies suitable for immunohistochemistry. To overcome this problem, an AID-specific monoclonal antibody suitable for immunohistochemical staining of formalin-fixed, paraffin wax-embedded tissue sections has been generated. This antibody was shown to detect AID expression in normal germinal centre B-cells as well as in non-Hodgkin lymphomas with a putative germinal centre origin. Using this antibody, a virtually exclusive cytoplasmic localization of AID in normal and neoplastic B-cells is shown. Employing a combination of immunohistochemistry and AID-specific in situ hybridization, it is demonstrated that AID is consistently expressed in the neoplastic cells of nodular lymphocyte-predominant Hodgkin lymphoma (HLnlp) but only infrequently in classical HL (cHL). This is in keeping with the notion that tumour cells of HLnlp represent transformed germinal centre B-cells showing evidence of somatic hypermutation. AID represents an additional marker useful in the differential diagnosis of HLnlp and cHL.

HOXB4 confers a constant rate of in vitro proliferation to transduced bone marrow cells

HOXB4 overexpression mediates increased self-renewal of haematopoietic stem cells (HSCs) ex vivo. Since HOXB4-expanded HSCs retain normal differentiation potential and there is no leukaemia development from transduced HSCs, HOXB4 represents a promising tool for human HSC therapy. However, the increased proliferation capacity of HOXB4 overexpressing fibroblasts resulting from upregulation of JunB, Fra-1 and cyclin D1 protein levels may indicate a potential risk associated with the HOXB4 overexpression approach. This prompted us to investigate the proliferation rate, differentiation and expression of cell cycle regulators directly in bone marrow cultures overexpressing HOXB4. Here we show that in comparison to neo-transduced control bone marrow cultures, HOXB4-overexpressing cultures had a more homogenous morphology and increased numbers of haematopoietic progenitor cells capable to generate primitive colonies in vitro. In contrast, neo-transduced bone marrow cells in long-term cultures showed hallmarks of myeloid differentiation and a reduced secondary colony forming activity. We further show that multilineage repopulating activity in vivo, which was present only in HOXB4 long-term cultures, declined over time. HOXB4 overexpression in vitro did not result in an increase but in a stabilization of the proliferation rate (1.4-1.8 cell divisions per day), while the proliferation rate of control neo-transduced bone marrow cultures gradually declined. Correspondingly, increased HOXB4 expression was paralleled by decreased expression levels of cyclins, CDKs and AP-1 family members. These results suggest that the growth rate of HOXB4- compared to neo-transduced bone marrow cells remains constant in long-term cultures along with a suppression of myeloid differentiation. In contrast to HOXB4 overexpression in fibroblasts, bone marrow cells engineered to overexpress HOXB4 do not upregulate AP-1 complex members or cyclins indicating that HOXB4 acts in a cell type-specific way.

Tumor induction by activated JNK occurs through deregulation of cellular growth

Activation of the cytoplasmic (Ras-Raf-MEK-ERK) signaling cascade was shown to be both, necessary and sufficient for transformation in vitro as well as in vivo. However, over the last years the involvement of stress-activated protein kinases (SAPKs)/Jun N-terminal kinases (JNKs), and their substrate c-Jun in the process of cellular transformation has been suggested. To dissect the mechanisms through which JNK signaling contributes to the transformation process we employed a recently generated constitutively active version of this kinase, SAPKbeta-MKK7, which behaves like a weakly transforming oncogene in vitro. Dissection of the transforming potential of oncogenic JNK demonstrates that it is sufficient for tumor induction in nude mice. In vitro studies and analysis of tumor material support the conclusion that oncogenic JNK primarily transforms through its effects on cell proliferation and tumor vascularization but does not affect cell survival.