Highlights d Proteomic profiles of extracellular vesicles and particles (EVPs) from 426 human samples d Identification of pan-EVP markers d Characterization of tumor-derived EVP markers in human tissues and plasma d EVP proteins can be useful for cancer detection and determining cancer type

Aberrant glucose metabolism is one of the hallmarks of cancer that facilitates cancer cell survival and proliferation. Here, we demonstrate that MUC1, a large, type I transmembrane protein that is overexpressed in several carcinomas including pancreatic adenocarcinoma, modulates cancer cell metabolism to facilitate growth properties of cancer cells. MUC1 occupies the promoter elements of multiple genes directly involved in glucose metabolism and regulates their expression. Furthermore, MUC1 expression enhances glycolytic activity in pancreatic cancer cells. We also demonstrate that MUC1 expression enhances in vivo glucose uptake and expression of genes involved in glucose uptake and metabolism in orthotopic implantation models of pancreatic cancer. The MUC1 cytoplasmic tail is known to activate multiple signaling pathways through its interactions with several transcription factors/coregulators at the promoter elements of various genes. Our results indicate that MUC1 acts as a modulator of the hypoxic response in pancreatic cancer cells by regulating the expression/stability and activity of hypoxia-inducible factor-1α (HIF-1α). MUC1 physically interacts with HIF-1α and p300 and stabilizes the former at the protein level. By using a ChIP assay, we demonstrate that MUC1 facilitates recruitment of HIF-1α and p300 on glycolytic gene promoters in a hypoxia-dependent manner. Also, by metabolomic studies, we demonstrate that MUC1 regulates multiple metabolite intermediates in the glucose and amino acid metabolic pathways. Thus, our studies indicate that MUC1 acts as a master regulator of the metabolic program and facilitates metabolic alterations in the hypoxic environments that help tumor cells survive and proliferate under such conditions. cancer metabolism | glutamine accumulation | pentose phosphate pathway | 2-ketoglutarate M UC1, a type I transmembrane protein, plays a significant role in the progression of cancer, particularly pancreatic adenocarcinoma (1-4). Although expressed in the normal pancreas, its expression is elevated in pancreatic adenocarcinoma and its expression pattern changes from a strictly apical localization on normal polarized epithelial cells to a broad distribution across the cell surface membrane of nonpolarized tumor cells (2). This results in aberrant signaling that enhances tumor progression and metastasis. MUC1 protein is expressed in >90% of pancreatic tumors (5), and MUC1 expression in tumors and its serum levels are associated with a poor prognosis and recurrence in patients with resected tumors (6). Much of the oncogenic role of MUC1 can be attributed to the participation of the small, cytoplasmic tail of MUC1 (MUC1.CT) in signal transduction and transcriptional events (2). ChIP-chip analyses have demonstrated that MUC1 occupies a plethora of promoter elements in which MUC1 modulates the recruitment and activity of transcription factors, thus regulating transcription of the corresponding genes (7).Several studies have established a role for MUC1 in tumor growth, invasion and metastas...

MUC1, an integral membrane mucin associated with the metastatic phenotype, is overexpressed by most human carcinoma cells. The MUC1 cytoplasmic tail (CT) is postulated to function in morphogenetic signal transduction via interactions with Grb2/Sos, c-Src, and ␤-catenin. We investigated intracellular trafficking of the MUC1 CT, using epitope-tagged constructs that were overexpressed in human pancreatic cancer cell lines S2-013 and Panc-1. The MUC1 CT was detected at the inner cell surface, in the cytosol, and in the nucleus of cells overexpressing MUC1. Fragments of the MUC1 CT were associated with ␤-catenin in both cytoplasm and nuclei. Overexpression of MUC1 increased steady state levels of nuclear ␤-catenin but decreased nuclear levels of plakoglobin (␥-catenin). There was no detectable association between plakoglobin and the MUC1 CT. Coimmunoprecipitation experiments revealed that the cytoplasmic and nuclear association of MUC1 CT and ␤-catenin was not affected by disruption of Ca 2؉ -dependent intercellular cadherin interactions. These results demonstrate nuclear localization of fragments of MUC1 CT in association with ␤-catenin and raise the possibility that overexpression of the MUC1 CT stabilizes ␤-catenin and enhances levels of nuclear ␤-catenin during disruption of cadherin-mediated cell-cell adhesion.Human MUC1 is a large, type I transmembrane protein normally expressed on the apical surface of ductal epithelia (1). Full-length MUC1 is synthesized as a single polypeptide chain, which undergoes an early proteolytic cleavage (probably in the endoplasmic reticulum) creating two subunits that remain associated during its post-translational processing and transport to the cell surface (2). The larger of the two fragments contains most of the extracellular domain, including the signal sequence and a tandem repeat domain (3-5). The smaller subunit contains a short extracellular domain, transmembrane domain, and cytoplasmic tail (CT), 1 which are highly conserved across species (88% identity with murine transmembrane and CT sequence) (6). The function of MUC1 is partially elucidated for normal and transformed cells. The extracellular fragment plays a significant role in configuring the adhesive and antiadhesive properties of cells and is believed to contribute to the establishment of molecular structures that protect the cell surface in the relatively harsh environment encountered by different ductal epithelia (7). However, the function of the intracellular portion of the MUC1 cytoplasmic tail (CT) is not known. Indirect evidence suggests that the MUC1 CT is involved in signal transduction, as it contains potential docking sites for Grb2/Sos and ␤-catenin, and can be phosphorylated by GSK-3␤, c-Src, EGFR, and PKC-␦ (7-16). This, together with the general transmembrane structure of the MUC1 molecule, suggests a potential role in morphogenetic signaling; however, little is known about mechanisms by which the MUC1 CT functions in this capacity, and nothing has been reported with regard to the relationship between...

We examined the steady-state expression levels of mRNA for the MUC1, MUC2, MUC3 and MUC4 gene products in 12 pancreatic tumor cell lines, 6 colon tumor cell lines, and one ileocecal tumor cell line. The results showed that 10 of 12 pancreatic tumor cell lines expressed MUC1 mRNA and that 7 of these 12 lines also expressed relatively high levels of MUC4 mRNA. In contrast, MUC2 mRNA was expressed at only low levels and MUC3 was not detected in the pancreatic tumor cell lines. All 7 intestinal tumor cell lines examined expressed MUC2, and 5 of 7 expressed MUC3; however only one expressed significant levels of MUC1 and 2 expressed low levels of MUC4 mRNA. This report of high levels of MUC4 mRNA expression by pancreatic tumor cells raises the possibility that mucin carbohydrate epitopes defined by antibodies such as DuPan 2 may be expressed on a second mucin core protein produced by pancreatic tumor cells.

MUC1is a highly glycosylated, type I transmembrane protein expressed by normal ductal epithelial cells of the pancreas, breast, lung, and gastrointestinal tract, and overexpressed in many cases of adenocarcinoma.We down-regulated MUC1expression by RNA interference and investigated the effects on malignant and metastatic potential of a human pancreatic cancer cell line, S2-013. MUC1-suppressed clones, S2-013.MTII.C1and S2-013.MTII.C2, were established by targeting a sequence 3,151 bp from the initiation codon and characterized in vitro for proliferation, invasion, and adhesion. We evaluated the effects of MUC1 suppression in vivo on tumor growth and metastatic properties following implantation into the cecum or pancreas of athymic mice. MUC1-suppressed clones showed significantly decreased proliferation in vitro and in vivo. Global gene expression was evaluated by oligonucleotide microarray analysis. Surprisingly, genes predicted to increase doubling times (cyclin B1 and cyclin D3) were overexpressed in MUC1-suppressed clones. There were alterations in expression of several genes that may affect the malignant properties of pancreatic cancer. Adhesion of MUC1-suppressed cells in vitro to type IV collagen and fibronectin was slightly increased, and adhesion was slightly decreased to type I collagen and laminin. Results of implantation to cecum and pancreas showed significant reduction of metastasis to lymph nodes, lung, or peritoneal sites compared with S2-013.gfp-neo control cells. These results support the hypothesis that MUC1 contributes significantly to growth and metastasis, and that down-regulation of MUC1 protein expression decreases the metastatic potential of pancreatic adenocarcinoma.In spite of recent efforts to improve prevention, screening, and therapy, pancreatic cancer has a poor prognosis: a 5-year survival rate of f3% and a median survival of <6 months (1). The poor prognosis is a consequence of metastatic disease that results from a lack of early detection and effective treatment. MUC1 is a polymorphic, highly glycosylated, type I transmembrane protein expressed by ductal epithelial cells of secretory organs, including the pancreas, breast, lung, and gastrointestinal tract (2), which is overexpressed and aberrantly glycosylated in most cases of adenocarcinoma. Previously, we investigated the role of MUC1 in invasion and metastasis by heterotopic implantation of tumor fragments onto the cecum of nude mice (3). Overexpressing full-length MUC1 in the pancreatic tumor cell line, S2-013, which expresses low levels of endogenous MUC1 and is spontaneously metastatic in the nude mouse model, altered the propensity for these cells to metastasize to lymph nodes and lungs.Overexpressing two mutant forms of MUC1, tandem repeat deleted [MUC1(CTR)] or cytoplasmic tail deleted (MUC1F.CT3), eliminated the phenotype and restored to control levels the degree of metastasis to lymph nodes and lung. DNA microarray analyses on clonal populations of these cells revealed very few differences in gene expression p...