Ligand of Numb proteins LNX1p80 and LNX2 interactwith the human glycoprotein CD8a and promote itsubiquitylation and endocytosis

E3 ubiquitin ligases give specificity to the ubiquitylation process by selectively binding substrates. Recently, their function has emerged as a crucial modulator of T-cell tolerance and immunity. However, substrates, partners and mechanism of action for most E3 ligases remain largely unknown. In this study, we identified the human T-cell co-receptor CD8 a-chain as binding partner of the ligand of Numb proteins X1 (LNX1p80 isoform) and X2 (LNX2). Both LNX mRNAs were found expressed in T cells purified from human blood, and both proteins interacted with CD8a in human HPB-ALL T cells. By using an in vitro assay and a heterologous expression system we showed that the interaction is mediated by the PDZ (PSD95-DlgA-ZO-1) domains of LNX proteins and the cytosolic C-terminal valine motif of CD8a. Moreover, CD8a redistributed LNX1 or LNX2 from the cytosol to the plasma membrane, whereas, remarkably, LNX1 or LNX2 promoted CD8a ubiquitylation, downregulation from the plasma membrane, transport to the lysosomes, and degradation. Our findings highlight the function of LNX proteins as E3 ligases and suggest a mechanism of regulation for CD8a localization at the plasma membrane by ubiquitylation and endocytosis

HOX D13 expression across 79 tumor tissue types.

HOX genes control normal development, primary cellular processes and are characterized by a unique genomic network organization. Locus D HOX genes play an important role in limb generation and mesenchymal condensation. Dysregulated HOXD13 expression has been detected in breast cancer, melanoma, cervical cancer and astrocytomas. We have investigated the epidemiology of HOXD13 expression in human tissues and its potential deregulation in the carcinogenesis of specific tumors. HOXD13 homeoprotein expression has been detected using microarray technology comprising more than 4,000 normal and neoplastic tissue samples including 79 different tumor categories. Validation of HOXD13 expression has been performed, at mRNA level, for selected tumor types. Significant differences are detectable between specific normal tissues and corresponding tumor types with the majority of cancers showing an increase in HOXD13 expression (16.1% normal vs. 57.7% cancers). In contrast, pancreas and stomach tumor subtypes display the opposite trend. Interestingly, detection of the HOXD13 homeoprotein in pancreas-tissue microarrays shows that its negative expression has a significant and adverse effect on the prognosis of patients with pancreatic cancer independent of the T or N stage at the time of diagnosis. Our study provides, for the first time, an overview of a HOX protein expression in a large series of normal and neoplastic tissue types, identifies pancreatic cancer as one of the most affected by the HOXD13 hoemoprotein and underlines the way homeoproteins can be associated to human cancerogenesis

Hepatic Notch1 deletion predisposes to diabetes and steatosis via glucose-6-phosphatase and perilipin-5 upregulation

Notch signaling pathways have recently been implicated in the pathogenesis of metabolic diseases. However, the role of hepatic Notch signaling in glucose and lipid metabolism remains unclear and needs further investigation as it might be a candidate therapeutic target in metabolic diseases such as nonalcoholic steatohepatitis (NASH) and nonalcoholic fatty liver disease (NAFLD). We used hepatocyte-specific Notch1 knockout (KO) mice and liver biopsies from NASH and NAFLD patients to analyze the role of Notch1 in glucose and lipid metabolism. Hepatocyte-specific Notch1 KO mice were fed with a high fat diet (HFD) or a regular diet (RD). We assessed the metabolic phenotype, glucose and insulin tolerance tests, and liver histology. Hepatic mRNA expression was profiled by Affymetrix Mouse Gene arrays and validated by quantitative reverse transcription PCR (qPCR). Akt phosphorylation was visualized by immunoblotting. Gene expression was analyzed in liver biopsies from NASH, NAFLD, and control patients by qPCR. We found that Notch1 KO mice had elevated fasting glucose. Gene expression analysis showed an upregulation of glucose-6-phosphatase, involved in the final step of gluconeogenesis and glucose release from glycogenolysis, and perilipin-5, a regulator of hepatic lipid accumulation. When fed with an HFD KO mice developed overt diabetes and hepatic steatosis. Akt was highly phosphorylated in KO animals and the Foxo1 target gene expression was altered. Accordingly, a reduction in Notch1 and increase in glucose-6-phosphatase and perilipin-5 expression was observed in liver biopsies from NAFLD/NASH compared with controls. Notch1 is a regulator of hepatic glucose and lipid homeostasis. Hepatic impairment of Notch1 expression may be involved in the pathogenesis of human NAFLD/NASH

p130Cas is an essential transducer element in ErbB2 transformation

The ErbB2 oncogene is often overexpressed in breast tumors and associated with poor clinical outcome. p130Cas represents a nodal scaffold protein regulating cell survival, migration, and proliferation in normal and pathological cells. The functional role of p130Cas in ErbB2-dependent breast tumorigenesis was assessed by its silencing in breast cancer cells derived from mouse mammary tumors overexpressing ErbB2 (N202-1A cells), and by its reexpression in ErbB2-transformed p130Cas-null mouse embryonic fibroblasts. We demonstrate that p130Cas is necessary for ErbB2-dependent foci formation, anchorage-independent growth, and in vivo growth of orthotopic N202-1A tumors. Moreover, intranipple injection of p130Cas-stabilized siRNAs in the mammary gland of Balbc-NeuT mice decreases the growth of spontaneous tumors. In ErbB2-transformed cells, p130Cas is a crucial component of a functional molecular complex consisting of ErbB2, c-Src, and Fak. In human mammary cells, MCF10A.B2, the concomitant activation of ErbB2, and p130Cas overexpression sustain and strengthen signaling, leading to Rac1 activation and MMP9 secretion, thus providing invasive properties. Consistently, p130Cas drives N202-1A cell in vivo lung metastases colonization. These results demonstrate that p130Cas is an essential transducer in ErbB2 transformation and highlight its potential use as a novel therapeutic target in ErbB2 positive human breast cancers.-Cabodi, S., Tinnirello, A., Bisaro, B., Tornillo, G., Camacho-Leal, M. P., Forni, G., Cojoca, R., Iezzi, M., Amici, A., Montani, M., Eva, A., Di Stefano, P., Muthuswamy, S. K., Tarone, G., Turco, E., Defilippi, P. p130Cas is an essential transducer element in ErbB2 transformation

The scaffolding protein flot2 promotes cytoneme-based transport of wnt3 in gastric cancer

This is the final version. Available on open access from eLife Sciences Publications via the DOI in this recordData availability: All data generated or analysed during this study are included in the manuscript, supporting files and source files; Supporting Data files and Source Data have been provided to all figures.The Wnt/β-catenin signalling pathway regulates multiple cellular processes during development and many diseases, including cell proliferation, migration, and differentiation. Despite their hydrophobic nature, Wnt proteins exert their function over long distances to induce paracrine signalling. Recent studies have identified several factors involved in Wnt secretion; however, our understanding of how Wnt ligands are transported between cells to interact with their cognate receptors is still debated. Here, we demonstrate that gastric cancer cells utilise cytonemes to transport Wnt3 intercellularly to promote proliferation and cell survival. Furthermore, we identify the membrane-bound scaffolding protein Flotillin-2 (Flot2), frequently overexpressed in gastric cancer, as a modulator of these cytonemes. Together with the Wnt co-receptor and cytoneme initiator Ror2, Flot2 determines the number and length of Wnt3 cytonemes in gastric cancer. Finally, we show that Flotillins are also necessary for Wnt8a cytonemes during zebrafish embryogenesis, suggesting a conserved mechanism for Flotillin-mediated Wnt transport on cytonemes in development and disease.Medical Research Council (MRC)Biotechnology and Biological Sciences Research Council (BBSRC

Skp2 expression is associated with high risk and elevated Ki67 expression in gastrointestinal stromal tumours

BACKGROUND: Gastrointestinal stromal tumors (GIST) exhibit an unpredictable clinical course and can rapidly progress to lethality. Predictions about the biological behavior of GIST are based on a number of canonical clinical and pathologic parameters whose validity in distinguishing between a benign and a malignant tumour is still imperfect. The aim of our study was to investigate the role of morphologic parameters and expression of cells cycle regulators as prognosticators in GIST. METHODS: We performed an immunohistochemical analysis for Ki67, p27Kip1, Jab1, and Skp2, on a Tissue Microarray (TMA) containing 94 GIST. Expression of the above proteins was correlated to classically used prognosticators, as well as to risk groups. Clinical significance of histologic and immunohistochemical features were evaluated in 59 patients for whom follow-up information was available. RESULTS: Overexpression of Ki67 and Skp2, and p27Kip1 loss directly correlated with the high risk group (p = 0.03 for Ki67 and Skp2, p = 0.05 for p27Kip1). Jab1 expression did not exhibit correlation with risk. In 59 cases provided with clinical follow-up, high cellularity, presence of necrosis, and Ki67 overexpression were predictive of a reduced overall survival in a univariate model. The same parameters, as well as mitotic rate, tumour size, and p27Kip1 loss were indicative of a shortened relapse free survival interval. High cellularity, and high mitotic rate retained their prognostic significance by multivariate analysis. CONCLUSION: Our data suggest that a number of histologic parameters in combination with immunohistochemical expression of cell cycle regulators can facilitate risk categorization and predict biologic behavior in GIST. Importantly this study demonstrates, for the first time, that Skp2 expression correlates with Ki67 expression and high risk in GIST

Prognostic impact of the expression of putative cancer stem cell markers CD133, CD166, CD44s, EpCAM, and ALDH1 in colorectal cancer

The aim of this study was to elucidate the prognostic impact of putative cancer stem cell markers CD133, CD166, CD44s, EpCAM, and aldehyde dehydrogenase-1 (ALDH1) in colorectal cancer

Cyclin H expression is increased in GIST with very-high risk of malignancy

<p>Abstract</p> <p>Background</p> <p>Risk estimation of gastrointestinal stromal tumours (GIST) is based on tumour size and mitotic rate according to the National Institutes of Health consensus classification. The indication for adjuvant treatment of patients with high risk GIST after R₀resection with small molecule inhibitors is still a controversial issue, since these patients represent a highly heterogeneous population. Therefore, additional prognostic indicators are needed. Here, we evaluated the prognostic value of cyclin H expression in GIST.</p> <p>Methods</p> <p>In order to identify prognostic factors of GIST we evaluated a single centre cohort of ninety-five GIST patients. First, GISTs were classified with regard to tumour size, mitotic rate and localisation according to the NIH consensus and to three additional suggested risk classifications. Second, Cyclin H expression was analysed.</p> <p>Results</p> <p>Of ninety-five patients with GIST (53 female/42 male; median age: 66.78a; range 17-94a) risk classification revealed: 42% high risk, 20% intermediate risk, 23% low risk and 15% very low risk GIST. In patients with high risk GIST, the expression of cyclin H was highly predictive for reduced disease-specific survival (p = 0.038). A combination of cyclin H expression level and high risk classification yielded the strongest prognostic indicator for disease-specific and disease-free survival (p ≤ 0.001). Moreover, in patients with tumour recurrence and/or metastases, cyclin H positivity was significantly associated with reduced disease-specific survival (p = 0.016) regardless of risk-classification.</p> <p>Conclusion</p> <p>Our data suggest that, in addition to high risk classification, cyclin H expression might be an indicator for "very-high risk" GIST.</p

Frequent high-level expression of the immunotherapeutic target Ep-CAM in colon, stomach, prostate and lung cancers

Epithelial cell adhesion molecule (Ep-CAM; CD326) is used as a target by many immunotherapeutic approaches, but little data are available about Ep-CAM expression in major human malignancies with respect to level, frequency, tumour stage, grade, histologic tumour type and impact on survival. We analysed by immunohistochemical staining tissue microarrays with 4046 primary human carcinoma samples from colon, stomach, prostate and lung cancers for both frequency and intensity of Ep-CAM expression under highly standardised conditions. A total of 3360 samples were analysable. High-level Ep-CAM expression was observed in 97.7% (n=1186) of colon, 90.7% of gastric (n=473), and 87.2% of prostate cancers (n=414), and in 63.9% of lung cancers (n=1287). No detectable Ep-CAM staining was found with only 0.4% of colon, 2.5% of gastric, 1.9% of prostate cancers, and 13.5% of lung cancers. The only significant correlation of Ep-CAM expression with tumour grading was observed in colon cancer where high-level Ep-CAM expression on grade 3 tumours was down to 92.1% (P<0.0001). Adenosquamous and squamous carcinomas of the lung had a lower percentage of high-level Ep-CAM expression compared to adenocarcinomas with 35.4 and 53.6%, respectively, and with 45.5 and 17.3% of tumours being Ep-CAM negative. With the exception of moderately differentiated colon carcinoma, where patients not expressing Ep-CAM on their tumours showed an inferior survival (P=0.0014), correlation of Ep-CAM expression with survival did not reach statistical significance for any of the other cancer indications and subgroups. In conclusion, the data strongly support the notion that Ep-CAM is a prime target for immunotherapies in major human malignancies. This is because the most common human cancers show (i) a low frequency of Ep-CAM-negative tumours, (ii) a high frequency of Ep-CAM expression on cells of a given tumour, and (iii) for most cancers, an insignificant influence of tumour staging, grading and histology on Ep-CAM expression