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The pancreatic cancer stem cell marker CD44v6 affects transcription, translation and signaling: consequences on exosome composition and delivery III

ABSTRACT: The miRNA profile between EXO from different pancreatic adenocarcinoma cells (A818.4, Capan-1) and different colorectal carcinoma cells (SW948, HT-29). The impact of a knockdown (kd) of function-relevant cancer stem cell markers (CD44v6, Tspan8, CD151, claudin7) on the EXO miRNA profile. The EXO kd cell miRNA profiles were compared with the wt cell EXO as well as between the different kd EXO miRNA profiles. These analyses were important to elaborate joint miRNA in the EXO profile from different cell lines as a starting point to elaborate possible functional activities of EXO including therapeutic translation.

ORGANISM(S): Homo sapiens

PROVIDER: GSE119033 | GEO | 2018/08/25

REPOSITORIES: GEO

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Project description:This project was done in collaboration with Dr. Richard Cummings to examine sialylation of CD44v6 and its role in clearance of neutrophils from inflamed intestinal epithelium. Specifically, we have employed a functional approach using membrane preparations from interferon gamma-stimulated intestinal epithelial cells to generate a monoclonal antibody, designated GM35, which blocks neutrophil transepithelial migration through the promotion of neutrophil adhesion at the apical surface of the intestinal epithelium. Protein biochemistry, sequencing, confocal microscopic analysis, and immunoprecipitation studies all identify the protein ligand for this antibody as CD44v6. However, selective inhibition of O- or N-linked glycosylation reveal that the antibody is specific for an O-linked glycotope and glycoarray analysis of the GM35 antibody by Core H of the Consortium for Functional Glycomics reveal that this antibody binds with high affinity and specificity to a carbohydrate epitope consistent in structure with sLeA. Inhibition of O-linked glycosylation attenuated both GM35 binding and its functional effects as did specific cleavage of sialic acid residues from the cell surface, using neuraminidase, although the functional effects of cleavage were smaller and harder to assess. CD44v6 has previously been studied as a marker of inflammation in Inflammatory Bowel Disease, and GM35 staining is clearly upregulated by interferon gamma in T84 and HT29 intestinal epithelial cells. The specific enzymes governing the sialylation of CD44v6 in intestinal epithelium have yet to be determined. Analysis of a panel of intestinal epithelial cells including T84, HT29, and Caco-2 cells revealed that cell-type specific regulation of both splicing and glycosylation is essential for the regulation of the expression of the GM35 epitope. And, forcible expression of CD44 in Caco-2 cells, which are negative for CD44v6 at baseline, results only in upregulation of previously expressed isoforms of CD44, but not in GM35 expression. Based on western blot and immunofluorescent staining, GM35 expression is greatest in interferon gamma-treated T84 cells. Thus, we analyzed RNA samples for the expression of glycosylation specific genes in interferon gamma-stimulated T84 cells relative to that of both non-stimulated T84 cells and GM35-negative Caco-2 cells in order to identify glycosylation-specific targets contributing to the interferon gamma-dependent upregulation of sialylated CD44v6 in intestinal epithelial cells.

Project description:Neuroblastoma (NB) is the most common extracranial solid tumor during infancy, causing up to 10% of mortality in children. NB shows notable heterogeneity with regard to histology and clinical behavior, ranging from low-risk localized tumors (LR-NB) to high-risk disease (HR-NB), characterized by aggressive metastatic phenotype, resistance to treatment, and fatal relapse occurrence. Risk stratification demands high accuracy, as it will determine the therapeutic treatment. However, the current therapeutic stratification, based on clinical and molecular risk factors, does not allow to discriminate among patients with similar clinical-pathological parameters who receive the same treatment despite showing markedly different clinical courses. The need of novel diagnostic molecular tools in oncology has led to increasing interest in liquid biopsies as a source of biomarkers, as they provide a minimally invasive method. Body fluids are a source of exosomes, nanosized extracellular vesicles that can drive tumor growth and chemoresistance. We previously identified exosomal microRNAs (exo-miRNA) indicative of HR-NB patient sensitivity/resistance to chemotherapy. As exosomes from cancer patients carry proteins that reflect the surface and cytoplasm content of parental cancer cells, including immunosuppressive molecules known to be associated with cancer progression and/or response to therapy, we extended our study to the exosomal proteins (Exo-prot).The purpose of the study is to identify Exo-prot that (i) are specifically expressed in NB patients and (ii) are associated with tumor phenotype and disease stage, in order to improve risk stratification and refine diagnosis.We isolated exosomes from plasma specimens of 24 HR-NB patients and 24 LR-NB patients at diagnosis and of 24 age-matched healthy controls (CTRL). Exo-prot expression was measured by liquid chromatography-mass spectrometry. Missing value distribution and differential expression analysis (performed with two different imputation methods) were applied to identify the most relevant Exo-prot. ROC analysis assessed the diagnostic value of the identified Exo-prot. We demonstrated that NB patients have a different Exo-prot expression profile compared to CTRL. The deregulated Exo-prot in NB specimens act mainly in tumor-associated pathways and build a strictly connected network. Furthermore, HR-NB patients show a different Exo-miR expression profile compared to LR-NB subjects, with the modulation of molecules involved in cell migration, proliferation and metastasis. Importantly, we show that NCAM, NCL, LUM and VASP have a diagnostic value in discriminating NB patients from CTRL; while MYH9, FN1, CALR, AKAP12 and, with a lower performance, LTBP1 can differentiate HR-NB and LR-NB patients with high accuracy. We demonstrated that Exo-prot deregulated in NB vs CTRL subjects and in HR-NB vs LR-NB patients contribute to NB tumor development and to the aggressive metastatic NB phenotype, respectively. We identified Exo-prot with significant diagnostic value for NB patients and able to efficiently identify the HR-NB subset of patients, which can be employed to improve risk stratification. Our results highlight the applicability of Exo-prot evaluation for integrating NB diagnosis and risk assessment.

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The pancreatic cancer stem cell marker CD44v6 affects transcription, translation and signaling: consequences on exosome composition and delivery III

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