Selenium-binding protein 1 (SELENBP1) expression is reduced in various epithelial cancer entities compared to corresponding normal tissue and has already been described as a tumor suppressor involved in the regulation of cell proliferation, senescence, migration and apoptosis. We identified SELENBP1 to be down-regulated in cutaneous melanoma, a malignant cancer of pigment-producing melanocytes in the skin, which leads to the assumption that SELENBP1 also functions as tumor suppressor in the skin, as shown by others e.g. for prostate or lung carcinoma.However, in vitro analyses indicate that SELENBP1 re-expression in human melanoma cell lines has no impact on cell proliferation, migration or tube formation of the tumor cells themselves when compared to control-transfected cells. Interestingly, supernatant taken from melanoma cell lines transfected with a SELENBP1 re-expression plasmid led to suppression of vessel formation of HMEC cells. Furthermore, SELENBP1 re-expression alters the sensitivity of melanoma cells for Vemurafenib treatment.The data also hint to a functional interaction of SELENBP1 with GPX1 (Glutathione peroxidase 1). Low SELENBP1 mRNA levels correlate inversely with GPX1 expression in melanoma. The re-expression of SELENBP1 combined with down-regulation of GPX1 expression led to reduction of the proliferation of melanoma cells. In summary, SELENBP1 influences the tumor microenvironment and SELENBP1 action is functionally influenced by GPX1.

Activation of the phosphatidylinositol-3-kinase (PI3K) signaling cascade is increasingly recognized as a common feature of thyroid follicular neoplasms. Among the PI3K downstream effectors, the main kinase, directly responsible for the increased cell growth and proliferation, is called mammalian target of rapamycin (mTOR). This central kinase might be directly inhibited via rapamycin and its derivatives. The aim of the present study was to examine whether RAD001 (everolimus) can selectively suppress the proliferation of different anaplastic thyroid cancer (ATC) cells. Five different human ATC cell lines were exposed to different concentrations of RAD001. Importantly, we found a dose-dependent growth inhibition in two ATC cell lines at concentrations of 43.5 and 94.5 nM although not as intensive as within the RAD001 responding K562cell line. The other cell lines revealed a GI (50) between 168 to 234 nM. In parallel, quantitative PCR of PCNA displayed a reduced expression of PCNA within the responding cell lines, respectively. In summary, we found a good responding effect in a part of ATC cell lines, which may have a clinical impact.

The deubiquitinase cylindromatosis (CYLD) is a well-known tumor suppressor, found to be down regulated in many cancer types including breast cancer, colon carcinoma and malignant melanoma. CYLD is suppressed in human melanoma cells by the transcriptional repressor SNAIL1 leading to an increase of their proliferative, invasive and migratory potential. To gain additional insights into the distinct function of this tumor suppressor gene a new mouse model Tg(Grm1)Cyld−/− was generated. Herewith, we demonstrate that Cyld-deficiency leads to earlier melanoma onset and accelerated tumor growth and metastasis in the GRM1 melanoma mouse model. First, RNA sequencing data revealed a potential role of CYLD in the regulation of genes involved in proliferation, migration and angiogenesis. Experiments using cell lines generated from both primary and metastatic melanoma tissue of Tg(Grm1) Cyld−/− and Tg(Grm1) Cyld+/+ mice confirmed that loss of CYLD enhances the proliferative and migratory potential, as well as the clonogenicity in vitro. Moreover, we could show that Cyld-knockout leads to increased vasculogenic mimicry and enhanced (lymph-) angiogenesis shown by tube formation assays, immunohistochemistry and mRNA expression analyses. In summary, our findings reveal new functional aspects of CYLD in the process of (lymph-) angiogenesis and demonstrate its importance in the early process of melanoma progression.

PTEN (phosphatase and tensin homologue deleted from chromosome 10) is a well established tumor suppressor gene, which was cloned to chromosome 10q23. PTEN plays an important role in controlling cell growth, apoptosis, cell adhesion, and cell migration. In various studies, a genetic change as well as loss of PTEN expression by different carcinomas has been described. To date, the role of PTEN as a differentiation marker for neuroendocrine tumors (NET) and for the loss of PTEN expression is still unknown. It is assumed that loss of PTEN expression is important for tumor progression of NETs. We hypothesize that PTEN might be used as a new prognostic marker. We report 38 patients with a NET of the pancreas. Tumor tissues were surgically resected, fixed in formalin, and embedded in paraffin. PTEN expression was evaluated by immunohistochemistry and was correlated with several clinical and pathological parameters of each individual tumor. After evaluation of our immunohistochemistry data using a modified Remmele Score, a widely accepted method for categorizing staining results for reports and statistical evaluation, staining results of PTEN expression were correlated with the clinical and pathological parameters of each individual tumor. Our data demonstrates a significant difference in survival with existence of lymph node or distant metastases. Negative patients show a significant better survival compared with positive patients. Furthermore, we show a significant difference between PTEN expression and WHO or TNM classification. Taken together, our data shows a positive correlation between WHO classification and the new TNM classification of NETs, and loss of PTEN expression as well as survival. These results strongly implicate that PTEN might be helpful as a new prognostic factor.

The sodium-iodide-symporter (NIS) plays a key role in iodination, the first step in the biosynthesis of the thyroid hormones, and is thought to be critically involved in several thyroid disorders associated with altered iodine up-take. To elucidate the pathogenic role of NIS in these diseases a sensitive technique is needed to measure human NIS gene expression. We established a real time RT-PCR for accurate quantification of hNIS mRNA levels based on fluorescence-labelled hybridisation probes in the LightCycler system. Human NIS expression was investigated in primary cultures of human thyrocytes. After optimisation of PCR conditions less than 10 molecules hNIS were detected with high sensitivity, specificity and reproducibility. Under basal conditions NIS expression varied from 83 to 593 copies per 10 6 GAPDH molecules. Stimulation of thyrocytes with TSH (0.1-10 U/ml) or forskolin (0.1-15 microM) results in a dose- and time-dependent up-regulation of NIS expression reaching a maximum at 10 mU/ml TSH (2211 +/- 761 copies) or 10 microM forskolin (1663 +/- 302 copies) after 24 h. In conclusion, we here established a real-time RT-PCR combining the advantages of rapid thermocycling and online detection of NIS mRNA amplification. The sensitive quantification of human NIS mRNA expression offered by this novel technique may improve analysis of hNIS regulation and measurement of NIS mRNA expression in small biopsies.