Bayer AG.

Epithelial-mesenchymal transition (EMT) is a fundamental cellular process in epithelial tissue development, and can be reactivated in cancer contributing to tumor invasiveness and metastasis. The cytokine transforming growth factor-β (TGFβ) is a key inducer of EMT, but the mechanisms that regulate TGFβ-induced EMT remain incompletely understood. Here, we report that knockdown of the ubiquitin ligase Smurf2 promotes the ability of TGFβ to induce EMT in a three-dimensional cell culture model of NMuMG mammary epithelial cells. In other studies, we identify Smurf2 as a target of the small ubiquitin like modifier (SUMO) pathway. We find that the SUMO-E2 conjugating enzyme Ubc9 and the SUMO E3 ligase PIAS3 associate with Smurf2 and promote its sumoylation at the distinct sites of Lysines 26 and 369. The sumoylation of Smurf2 enhances its ability to induce the degradation of the TGFβ receptor and thereby suppresses EMT in NMuMG cells. Collectively, our data reveal that Smurf2 acts in a sumoylationregulated manner to suppress TGFβ-induced EMT. These findings have significant implications for our understanding of epithelial tissue development and cancer. Cell Death and Differentiation (2016) 23, 876-888; doi:10.1038/cdd.2015; published online 18 December 2015Epithelial-mesenchymal transition (EMT) is an essential process in epithelial tissue morphogenesis in the developing organism and contributes to postnatal events including mammary postnatal gland development as well as wound healing.1,2 Importantly, EMT can be reactivated during cancer and may contribute to tumor invasiveness.3 Epithelial cells undergoing EMT change phenotypically from cuboidal to fibroblastic morphology, lose epithelial markers including E-cadherin, gain mesenchymal markers, and display increased cell motility and invasiveness. 4,5 The secreted factor transforming growth factor-β (TGFβ) has emerged as a potent inducer of EMT with key roles in development and cancer.6 Thus, there has been interest in the mechanisms that mediate TGFβ-induced EMT.Smurf2 (Smad (Sma and mad) ubiquitination regulatory factor-2) is a HECT (for homology to E6 carboxy terminus domain)-containing E3 ubiquitin ligase that specifies substrates for ubiquitination and degradation by the proteasome.7,8 Smurf2 regulates key biological processes during development and homeostasis including cell polarity, cell cycle, and senescence in an E3 ligase-dependent or -independent manner.9-15 The biological functions of Smurf2 occur via regulation of signaling pathways including the TGFβ-Smad signaling pathway. [16][17][18][19][20][21][22][23] However, the role of Smurf2 in TGFβ-induced EMT has remained to be determined.Sumoylation refers to the covalent attachment of the small ubiquitin-like modifier (SUMO), to protein substrates by the SUMO pathway.24 SUMO is linked to its substrates by an iso-peptide bond between C-terminal carboxyl group of SUMO and ε-amino group of a lysine residue in the substrate. The SUMO E2 conjugating enzyme Ubc9, the second enzyme of a three-step catalytic cascade...

Background: Epithelial-mesenchymal transition (EMT) plays critical roles in tissue development and cancer biology. Results: TIF1␥ promotes sumoylation of SnoN1 and, thereby, regulates EMT. Conclusion: A novel TIF1␥-SnoN1 sumoylation pathway is crucial for the suppression of EMT. Significance: The identification of the TIF1␥-SnoN1 sumoylation signaling link advances our understanding of EMT.

MS4A4A is a member of the membrane-spanning, four domain family, subfamily A (MS4A) that includes CD20 (MS4A1), FcRβ (MS4A2) and Htm4 (MS4A3). Like the first three members of this family, transcription of MS4A4A appears to be limited to hematopoietic cells. To evaluate expression of the MS4A4A protein in hematopoietic cell lineages and subsets we generated monoclonal antibodies against extracellular epitopes for use in flow cytometry. In human peripheral blood we found that MS4A4A is expressed at the plasma membrane in monocytes but not in granulocytes or lymphocytes. In vitro differentiation of monocytes demonstrated that MS4A4A is expressed in immature but not activated dendritic cells, and in macrophages generated in the presence of interleukin-4 ('alternatively activated' or M2 macrophages) but not by interferon-γ and lipopolysaccharide ('classically' activated or M1 macrophages). MS4A4A was expressed in the U937 monocytic cell line only after differentiation. In normal bone marrow, MS4A4A was expressed in mature monocytes but was undetected, or detected at only a low level, in myeloid/monocytic precursors, as well as their malignant counterparts in patients with various subtypes of myeloid leukemia. Although MS4A4A was not expressed in healthy B lymphocytes, it was highly expressed in normal plasma cells, CD138+ cells from multiple myeloma patients, and bone marrow B cells from a patient with mantle cell lymphoma. These findings suggest immunotherapeutic potential for MS4A4A antibodies in targeting alternatively activated macrophages such as tumor-associated macrophages, and in the treatment of multiple myeloma and mantle cell lymphoma.

Abstract.Increasing evidence has shown that cancer stem cells or tumor initiating cells are the 'root cause' of malignant cancers. However, the exact origin of cancer stem cells still remains obscure in thyroid research. EMT has been implicated in the initiation and conversion of early-stage tumors into invasive malignancies and is associated with the stemness of cancer cells. Based on these facts, a new hypothesis was suggested that EMT induces cancer stem cell generation and tumor progression in human thyroid cancer cells in vitro. In the present study, FTC133 cells identified as EMT-negative cells were used for EMT induction by HIF-1α transfection. Overexpression of HIF-1α induced FTC133 cells to undergo EMT, downregulated the epithelial markers E-cadherin, upregulated the mesenchymal marker vimentin, and associated with highly invasive and metastatic properties. Most importantly, the induction of EMT promoted the stem-like side population cell proportion in the FTC133 cells. These results indicate that EMT induction promotes CSC traits and cell proportions in the thyroid cancer cells, which implies that EMT could induce cancer stem cell generation and tumor progression in thyroid cancers. Further understanding of the role of EMT and cancer stem cells in cancer progression may reveal new targets for the prevention or therapy of thyroid cancers. IntroductionAnaplastic thyroid carcinoma is an aggressive malignancy characterized by an extensive local invasion, early systemic dissemination and marked resistance to chemo-and radiotherapy, and always has a poor prognosis with a mean survival of only few months (1). Current systemic therapy fails to eradicate this cancer or even to stop tumor progress. It has been hypothesized that this may be explained by the failure of current drugs to effectively target cancer stem-like cells (CSCs) (2,3). To date, CSCs have been reported in various solid tumors and in cancer cell lines (4-9). However, until recently, there are only very few studies on adult thyroid stem/progenitor cells and thyroid CSCs (10-12). We and others have recently described and characterized thyroid cancer stem cells as a side population (13-17) that may play a critical role in the progression and recurrence of cancer and its subsequent metastasis (18).Epithelial to mesenchymal transition (EMT) is a vital process for morphogenesis during embryonic development, but it has also been implicated in the conversion of early stage tumors into invasive malignancies (19). More recent studies have further demonstrated that EMT plays a critical role not only in tumor metastasis but also in tumor recurrence that is believed to be tightly linked with the biology of cancer stem-like cells or cancer-initiating cells (20-23). The relationship between EMT and CSCs has been observed, with the evidence suggesting that EMT cells acquire stem cell-like traits and that CSCs exhibit a mesenchymal-like appearance in immortalized non-tumorigenic mammary epithelial cells and breast cancers (22). In thyroid cancer, it was found i...