Publications (54) View all
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Article: WNT5A-NFAT Signaling Mediates Resistance to Apoptosis in Pancreatic Cancer.
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ABSTRACT: WNT5A belongs to the Wnt family of secreted signaling molecules. Using transcriptional profiling, we previously identified WNT5A as target of the antiapoptotic transcription factor CUX1 and demonstrated high expression levels in pancreatic cancer. However, the impact of WNT5A on drug resistance and the signaling pathways employed by WNT5A remain to be elucidated. This project aims to decipher the impact of WNT5A on resistance to apoptosis and the signaling pathways employed by WNT5A in pancreatic cancer. The impact of WNT5A and its downstream effectors on tumor growth and drug resistance was studied in vitro and in xenograft models in vivo. Tissue microarrays of pancreatic cancer specimens were employed for immunohistochemical studies. Knockdown of WNT5A results in a significant increase in drug-induced apoptosis. In contrast, overexpression of WNT5A or addition of recombinant WNT5A mediates resistance to apoptosis in vitro. In our attempt to identify downstream effectors of WNT5A, we identified the transcription factor nuclear factor of activated T cells c2 (NFATc2) as transcriptional target of WNT5A signaling. NFATc2 confers a strong antiapoptotic phenotype mediating at least in part the effects of WNT5A on drug resistance and tumor cell survival. In vivo, WNT5A expression leads to resistance to gemcitabine-induced apoptosis in a xenograft model, which is paralleled by up-regulation of NFATc2. Both WNT5A and NFATc2 proteins are highly expressed in human pancreatic cancer tissues and their expression levels correlated significantly. We identified the WNT5A-NFATc2 axis as important mediator of drug resistance in pancreatic cancer.Neoplasia (New York, N.Y.) 01/2013; 15(1):11-22. · 5.48 Impact Factor -
Article: Current concepts and novel targets in advanced pancreatic cancer.
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ABSTRACT: Pancreatic cancer remains one of the most aggressive tumours with a 5-year survival rate of less than 5%. The dismal prognosis of this tumour entity that is associated with a high degree of drug resistance has not changed over the past decades. Since 1997, gemcitabine-based regimens have been the therapy of choice for advanced pancreatic cancer. Recently, however, new combination chemotherapy regimens achieved a significant survival benefit compared to gemcitabine-based therapies. In addition, novel approaches to improve drug delivery are currently being developed, and new drugs targeting signalling pathways both within the tumour cells and the tumour microenvironment are undergoing preclinical and clinical validation. Furthermore, efforts are being made to identify predictive markers for individualised treatment approaches based on molecular tumour characteristics. This review provides an overview on current and emerging concepts as well as novel targets for systemic treatment of advanced pancreatic cancer. Combination therapies incorporating drugs directed against these new targets may open new avenues for improving the efficacy of current treatment approaches and overcoming the devastating prognosis of pancreatic cancer patients.Gut 10/2012; · 10.11 Impact Factor -
Article: Claudin-4-targeted optical imaging detects pancreatic cancer and its precursor lesions.
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ABSTRACT: OBJECTIVES: Novel imaging methods based on specific molecular targets to detect both established neoplasms and their precursor lesions are highly desirable in cancer medicine. Previously, we identified claudin-4, an integral constituent of tight junctions, as highly expressed in various gastrointestinal tumours including pancreatic cancer. Here, we investigate the potential of targeting claudin-4 with a naturally occurring ligand to visualise pancreatic cancer and its precursor lesions in vitro and in vivo by near-infrared imaging approaches. DESIGN: A non-toxic C-terminal fragment of the claudin-4 ligand Clostridium perfringens enterotoxin (C-CPE) was labelled with a cyanine dye (Cy5.5). Binding of the optical tracer was analysed on claudin-4 positive and negative cells in vitro, and tumour xenografts in vivo. In addition, two genetically engineered mouse models for pancreatic intraepithelial neoplasia (PanIN) and pancreatic cancer were used for in vivo validation. Optical imaging studies were conducted using 2D planar fluorescence reflectance imaging (FRI) technology and 3D fluorescence-mediated tomography (FMT). RESULTS: In vitro, the peptide-dye conjugate showed high binding affinity to claudin-4 positive CAPAN1 cells, while claudin-4 negative HT1080 cells revealed little or no fluorescence. In vivo, claudin-4 positive tumour xenografts, endogenous pancreatic tumours, hepatic metastases, as well as preinvasive PanIN lesions, were visualised by FRI and FMT up to 48 h after injection showing a significantly higher average of fluorochrome concentration as compared with claudin-4 negative xenografts and normal pancreatic tissue. CONCLUSIONS: C-CPE-Cy5.5 combined with novel optical imaging methods enables non-invasive visualisation of claudin-4 positive murine pancreatic tumours and their precursor lesions, representing a promising modality for early diagnostic imaging.Gut 06/2012; · 10.11 Impact Factor -
Article: Improving drug delivery to pancreatic cancer: breaching the stromal fortress by targeting hyaluronic acid.
Gut 06/2012; 61(10):1377-9. · 10.11 Impact Factor -
Article: Pancreatic cancer — Outlook: targeted therapy
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ABSTRACT: Pancreatic cancer is a devastating disease characterized by almost identical incidence and mortality rates. Since this tumour is mostly diagnosed in an advanced stage there is usually no option for a curative surgical resection. In addition, pancreatic cancers known to be resistant to conventional treatment modalities such as chemotherapy and radiotherapy. Therefore, novel strategies for targeting these tumors are urgently needed. The increasing knowledge on the underlying pathogenetic mechanisms has led to the identification of surface receptor molecules that initiate intracellular signalling cascades upon ligand binding, thus leading to tumor progression. Targeting these receptors or their secreted ligands is therefore an attractive new approach for cancer therapy. The epidermal growth factor receptor (EGFR) and the vascular endothelial growth factor receptor (VEGFR) are transmembrane tyrosine kinase receptors which can be targeted by various compounds such as antibodies or small molecule inhibitors. In addition, various molecules targeting proteins secreted by pancreatic cancers such as matrix metalloproteinases (MMP’s) or intracellular oncogenic signalling components such as the farnesyl-transferase have been proposed as potential new approaches for targeted cancer therapy. The use of these agents alone or in combination with conventional therapeutic regimens is currently being evaluated and shows first promising results for pancreatic cancer therapy.The Chinese-German Journal of Clinical Oncology 04/2012; 6(2):176-180.
