Enhancement of metastatic properties of pancreatic cancer cells by MUC1 gene encoding an anti-adhesion molecule

MUC1, MUC2, MUC4, MUC5AC and MUC6 expression in the progression of prostate cancer

Molecular changes are vital for the development of prognostic markers and therapeutic modalities of prostate cancer (CaP). There is growing interest in mucins as treatment targets in human malignancies, including CaP. The role of their expression in the progression of CaP is however unclear. We examined the expressions MUC1, MUC2, MUC4, MUC5AC and MUC6 in CaP tissues using tissue microarrays (TMAs) to look for tumor-associated antigens (TAAs) for targeted therapy. In this study, 120 paraffin-embedded specimens were selected from patients who underwent radical retro-pubic prostatectomy (RRP) or trans-urethral-resection of the prostate (TURP) for primary, untreated CaP and 10 matched lymph node metastases. A series of MUC monoclonal antibodies (mAbs) was used on TMAs by standard immunohistochemistry. Our results indicate that the over-expression of MUC1 was detected in 58% of primary CaP tissues and 90% of lymph node metastases but not in normal prostate or benign tissues, while the expression of MUC2, MUC4, MUC5AC and MUC6 was found to be negative in both normal and cancer tissues. Of the MUC1 positive tumors 86% were Gleason grade 7 or higher. Over-expression of MUC1 was found in late stage CaP while MUC2, 4, 5AC and 6 were negative in CaP. MUC1 is a TAA that is highly related to tumor progression in CaP patients. This antigen is ideal for targeted therapy to control micrometastases and hormone refractory disease but additional studies are necessary to assess its usefulness in patient biopsies and CaP bone metastases before clinical trial.

Intraductal papillary mucinous neoplasms of the pancreas: A surgical perspective

Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas represent a relatively "new", but increasingly recognized entity. The emergence of this entity is due primarily to the widespread use of modern imaging methods, but also to a heightened awareness of physicians regarding this cystic neoplasm of the pancreas. No signs or symptoms are pathognomonic of IPMNs, but frequently, patients have a pancreatitis-like abdominal pain. Fully one-third of patients with IPMN are asymptomatic at the time of diagnosis. Cross-sectional imaging (ultrasonography, computed tomography, magnetic resonance cholangiopancreatography), endoscopic retrograde cholangiopancreatography, and endoscopic ultrasonography are the diagnostic and staging methods of choice in the evaluation of patients with IPMNs. IPMNs show a wide spectrum of histologic changes, ranging from adenoma to invasive neoplasm, even within the same neoplasm, suggesting a "field defect" predisposing major segments or even the entire ductal epithelium to the development of IPMN. Fine-needle aspiration/cytology and/or analysis of the cystic fluid may be useful diagnostic tools; however, these examinations are associated with high false-negative rates. Complete surgical resection is the therapeutic method of choice. The extent and type of pancreatectomy remain somewhat controversial but should be based on morphologic changes of the pancreas. Even the role of adjuvant therapy remains unclear; however, being "duct-derived" neoplasms of potential malignant character, some form of adjuvant chemo- or ratio-therapy seems indicated in the presence of invasive disease, despite a "curative" resection. In the absence of invasive disease, prognosis after R0 resection is highly favorable with recurrences of 5-10%. However, invasive IPMNs behave quite similar to ductal adenocarcinoma of the pancreas when analyzed stage-by-stage, with a slightly better prognosis; however, even after an R0 resection, recurrence is common.

Recent advances on the molecular mechanisms involved in pancreatic cancer progression and therapies

This review describes the recent advances in the molecular events involved in pancreatic cancer initiation, progression, and metastasis. Additionally, the importance of deregulated cellular signaling elements as potential targets for developing novel therapeutic strategies against incurable forms of pancreatic cancer is reported. The emphasis is on the critical functions gained by numerous growth factors and their receptors, such as epidermal growth factor receptor, hedgehog signaling, and proangiogenic agents such as vascular endothelial factor and interleukin-8 for the sustained growth, survival, and metastasis of pancreatic cancer cells. The molecular mechanisms associated with antitumoral properties and the clinical benefits of gemcitabine alone or in combination with other cytotoxic agents for the treatment of pancreatic cancer are discussed.

Expression of MUC1 and its significance in hepatocellular and cholangiocarcinoma tissue

AIM: To investigate the relation between MUC1 expression, distribution, and prognosis in hepatocellular and cholangiocarcinoma (HCC and CC) and cirrhotic liver tissues, and their significance in HCC and CC diagnosis.

METHODS: Expression and distribution of MUC1 were examined by immunohistochemical assay with anti-MUC1 mAb in 59 samples of HCC and 37 samples of CC, 20 samples of cirrhotic liver tissues, and 10 samples of normal liver tissues, seeking possible associations between MUC1 positive expression, distribution in HCC and CC (primary liver cancer, PLC) cases and the studied clinical data.

RESULTS: Immunohistochemical analysis of MUC1 expression showed that in the 96 PLC samples, 68 (70.8%) were strong positive, and 6 (6.2%) were weak positive. Only 4 in the 20 cirrhotic liver tissues were found to be weak positive, while no expression of MUC1 was detected in normal liver tissues. Apparently, the high expression rate of MUC1 in PLC tissues was statistically significant in comparison to that in cirrhotic and normal liver tissues. The expressed MUC1 protein, stained in dark brownish or brownish-yellow particles, chiefly localized on the cancer cell membranes or in cytoplasm. In the 68 strong positive samples, 40 were detected on cell membrane and the other 28 were in cytoplasm. In addition, follow-up studies of those PLC cases demonstrated that MUC1 expression on cell membrane or in cytoplasm was closely associated with PLC prognosis. The expression of MUC1 in PLC had little statistical significance in respect of the pathological types and sizes of the tumors, but a strong relationship regarding histological differentiation, metastasis of lymph nodes, portal canal emboli, and post-operational recurrence of the carcinomas. After 3 years of tumor excision, the metastasis rate in MUC1 positive expression group (67.6%) was much higher than that in MUC1 weak expression group (33.3%) and negative expression group (31.8%), and thus the survival rate in MUC1-positive expression group was significantly different from that in weak and negative expression groups.

CONCLUSION: Expression and localization of MUC1 proteins in primary liver carcinomas (PLCs) may act as prognostic markers, and MUC1 molecules might be helpful in differential diagnosis.

Stable expression of sialyl-Tn antigen in T47-D cells induces a decrease of cell adhesion and an increase of cell migration

Sialyl-Tn is a carbohydrate antigen overexpressed in several epithelial cancers including breast cancer, and usually associated with poor prognosis. Sialyl-Tn is synthesized by a CMP-Neu5Ac: GalNAc alpha2,6-sialyltransferase: ST6GalNAc I, which catalyzes the transfer of a sialic acid residue in alpha2,6-linkage to the GalNAcalpha1-O-Ser/Thr structure. The resulting disaccharide (Neu5Acalpha2-6GalNAcalpha1-O-Ser/Thr) cannot be further elongated and sialyl-Tn expression results therefore in a shortening of the O-glycan chains. However, usual breast cancer cell lines express neither ST6GalNAc I nor sialyl-Tn antigen. We have previously shown that stable transfection of MDA-MB-231 cells with the hST6GalNAc I cDNA induces the sialyl-Tn antigen expression at the cell surface and leads to a decreased cell growth and an increased cell migration. We describe herein the generation of new T47-D clones expressing sialyl-Tn antigen after hST6GalNAc I cDNA stable transfection. sialyl-Tn antigen is carried by several high molecular weight membrane bound O-glycoproteins, including MUC1. We show that sialyl-Tn expression induces a decrease of cell growth and adhesion, and an increase of cell migration in sialyl-Tn positive clones compared to mock transfected cells. These observations show that the alteration of the O-glycans pattern is sufficient to modify the biological features of cancer cells. These T47-D sialyl-Tn expressing clones might allow further in vivo investigation to determine precisely the impact of such O-glycosylation modifications on breast cancer development.

MUC1 expression in primary and metastatic pancreatic cancer cells for in vitro treatment by (213)Bi-C595 radioimmunoconjugate

Control of micrometastatic pancreatic cancer remains a major objective in pancreatic cancer treatment. The overexpression of MUC1 mucin plays an important role in cancer metastasis. The aim of this study was to detect the expression of MUC1 in human primary tumour tissues and three pancreatic cancer cell lines (CAPAN-1, CFPAC-1 and PANC-1), and target MUC1-positive cancer cells in vitro using ²¹³Bi-C595 alpha-immunoconjugate (AIC). The expression of MUC1 on pancreatic tumour tissues and cancer cell lines was performed by immunohistochemistry and further confirmed by confocal microscope and flow cytometry analysis on the cell surface. Cytotoxicity of ²¹³Bi-C595 was tested by MTS assay. Apoptosis was documented using TUNEL assay. Overexpression of MUC1 was found in ∼90% of tested tumour samples and the three pancreatic cancer cell lines. ²¹³Bi-C595 is specifically cytotoxic to pancreatic cancer cells in a concentration-dependent fashion. These results suggest that overexpression of MUC1 in pancreatic cancer is a useful target, and that the novel ²¹³Bi-C595 AIC selectively targets pancreatic cancer cells in vitro. ²¹³Bi-C595 may be a useful agent for the treatment of micrometastases or minimal residual disease (MRD) in pancreatic cancer patients with overexpression of MUC1 antigen.

MUC4 and ErbB2 expression in squamous cell carcinoma of the upper aerodigestive tract: correlation with clinical outcomes

OBJECTIVES/HYPOTHESIS

Expression of the membrane mucin MUC4 has been associated with a variety of malignancies, including squamous cell carcinoma of the upper aerodigestive tract. MUC4 modulates cell signaling pathways as an intramembrane ligand of ErbB2. The hypotheses of the study were that MUC4 expression would correlate with ErbB2 expression and that MUC4 expression would correlate with clinical outcomes in squamous cell carcinoma of the upper aerodigestive tract.

STUDY DESIGN

Retrospective chart review was combined with immunohistochemical analysis of paraffin-embedded tumor specimens from patients treated with initial definitive surgical resection at an academic tertiary care medical center.

METHODS

MUC4 and ErbB2 receptor expression was localized by immunohistochemical studies using archival formalin-fixed and paraffin-embedded tissue. A limited number of fresh-frozen tissues were further analyzed by Western blot. Clinical outcomes and histopathological parameters were determined by retrospective chart review and correlated with immunohistochemical findings.

RESULTS

One hundred fifty-four patients were analyzed with a median follow-up of 12 months among 54 patients who died and 49 months among 100 surviving patients. Membrane expression of MUC4 and ErbB2 was seen in 12% and 13% of tumors, respectively. MUC4 expression was not correlated with pathological grade. A significant correlation was found between MUC4 expression and ErbB2 expression. Multivariate survival analyses revealed that patients whose tumors exhibited MUC4 membrane expression had statistically significant improvement in survival and longer time to recurrence compared with patients whose tumors did not express MUC4 as defined by immunohistochemical staining patterns. No correlations between ErbB2 expression and survival or recurrence were observed.

CONCLUSION

Patients with tumors that retain MUC4 expression exhibit improved survival and decreased recurrence in squamous cell carcinoma of the upper aerodigestive tract. Correlations between MUC4 expression patterns and ErbB2 expression are also observed, suggesting that MUC4-ErbB2 mediated cell signaling pathways may provide insights into this clinical result.

Pathologically and biologically distinct types of epithelium in intraductal papillary mucinous neoplasms: delineation of an "intestinal" pathway of carcinogenesis in the pancreas

Although general characteristics of intraductal papillary mucinous neoplasms (IPMNs) and their delineation from other pancreatic tumors have been well established, several issues regarding their biology and management remain unresolved. It has been noted briefly by us and other authors that there are different types of papillae in IPMNs; however, their frequency, biologic significance, and clinical relevance are unknown. In this study, the association of different papillary patterns with clinical, pathologic, and biologic parameters was studied in 74 IPMNs, and the expression profile of CDX2 (a specific marker and one of the key determinants of intestinal "programming," and a tumor suppressor) was determined immunohistochemically in addition to MUC1 (a marker of an "aggressive" phenotype in pancreatic neoplasia) and MUC2 ("intestinal type mucin," a marker of the "indolent" phenotype, and a tumor suppressor). The patterns of papillae identified and their association with these parameters were as follows: 1) The intestinal-type (Yonezawa's dark-cell type), similar to villous adenomas, was seen in 26 of 74 (35%) cases. The majority harbored carcinoma in situ (85%) or borderline atypia (15%). They tended to be large (mean, 5.5 cm). Most expressed CDX2 (95%) and MUC2 (92%) but not MUC1 (8%). This type was more commonly associated with colloid-type invasion (14 of 16 invasive carcinomas were of colloid type). 2) The pancreatobiliary type, characterized by arborizing papillae lined by cuboidal cells resembling papillary neoplasms of the biliary tract, was present in 22% of the cases. These were mostly graded as carcinoma in situ (94%); they rarely expressed CDX2 (6%) or MUC2 (19%) but often showed MUC1 labeling (44%). This pattern was more commonly associated with the tubular type of invasive carcinoma and had a slight tendency for a more aggressive clinical course. 3) The null type was characterized by abundant apical mucin and basally located nuclei, similar to the gastric foveolar epithelium. Thirty-one percent of IPMNs had this type of papillae, but this pattern was also present in the background of other IPMNs and in the cystic components of most cases as well. Most pure null-type IPMNs were devoid of complexity and consequently classified as adenoma (48%). They tended to be small (mean, 2.6 cm), were often negative for CDX2, MUC1, and MUC2, and were rarely associated with invasive carcinoma. 4) Some IPMNs (12%) exhibited features that were difficult to classify, and 2 cases had a mixture of pancreatobiliary and intestinal types of papillae. In conclusion, IPMNs include pathologically and biologically distinct epithelial patterns. CDX2 and MUC2 expression is relatively specific for the intestinal type papillae, confirming that these IPMNs indeed exhibit intestinal differentiation. Their close association with colloid carcinoma, which also shows consistent MUC2 and CDX2 expression, supports the existence of an intestinal pathway of carcinogenesis. This "metaplastic" pathway may reflect different genetic events in the development of these IPMNs, and the presence of intestinal differentiation may potentially be used in prognostication and stratification of patients into appropriate treatment categories.

Inhibition ofMUC4Expression Suppresses Pancreatic Tumor Cell Growth and Metastasis

The MUC4 mucin is a high molecular weight membrane-bound glycoprotein. It is aberrantly expressed in pancreatic tumors and tumor cell lines with no detectable expression in the normal pancreas. A progressive increase of MUC4 expression has also been observed in pancreatic intraepithelial neoplasia, suggesting its association with disease development. Here, we investigated the consequences of silencing MUC4 expression in an aggressive and highly metastatic pancreatic tumor cell line CD18/HPAF that expresses high levels of MUC4. The expression of MUC4 was down-regulated by the stable integration of a plasmid-construct expressing antisense-MUC4 RNA. A decrease in MUC4 expression, confirmed by Western blot and immunofluorescence analyses, resulted in diminished growth and clonogenic ability of antisense-MUC4-transfected (EIAS19) cells compared with parental, empty vector (ZEO) and sense transfected (ES6) control cells. In addition, EIAS19 cells displayed a significant decrease in tumor growth and metastatic properties when transplanted orthotopically into the immunodeficient mice. In vitro biological assays for motility, adhesion, and aggregation demonstrated a 3-fold decrease in motility of EIAS19 cells compared with control cells, whereas these cells adhered more and showed an increase in cellular aggregation. Interestingly, MUC4 down-regulation also correlated with the reduced expression of its putative interacting partner, HER2/neu, in antisense-MUC4-transfected cells. In conclusion, the present work demonstrates, for the first time, a direct association of the MUC4 mucin with the metastatic pancreatic cancer phenotype and provides experimental evidence for a functional role of MUC4 in altered growth and behavioral properties of the tumor cell.

Inhibition of MUC1 expression by indole-3-carbinol

MUC1 is a large transmembrane glycoprotein overexpressed by a majority of carcinomas. High expression of MUC1 is associated with aggressive tumors, and MUC1 antigen is used as a marker to monitor disease progression in breast cancer patients. Several lines of evidence strongly suggest that the overexpression of MUC1 contributes to cancer progression and metastasis. In this report, we demonstrate that the naturally occurring cancer preventative, indole-3-carbinol (I3C), inhibits the expression of MUC1 in breast cancer cells. I3C inhibited both MUC1 mRNA and protein levels in a dose- and time-dependent manner. This inhibition was seen in the estrogen responsive MCF-7 cells as well as unresponsive MDA-MB-468 cells, indicating that the inhibitory pathway is independent of estrogen receptor. Gene expression studies using the human MUC1 gene promoter connected to a luciferase reporter demonstrated that I3C inhibits the transcription of the MUC1 gene. Promoter deletion studies indicate that the region containing up to 600 bp upstream (-600) of the initiation site is sufficient for inhibition by I3C. Furthermore, I3C represses the activation of transcription mediated by the region between -600 and -450 bp. A putative xenobiotic response element was located within this region but the binding of AhR/Arnt heterodimer to this site was undetectable by electrophoretic mobility shift assays. Our results may point to the existence of a novel pathway of transcriptional inhibition by I3C in cancer cells as well as a new mechanism of MUC1 gene inhibition. Our findings might have implications in the use of I3C as a preventative as well as a therapeutic agent for breast cancer.

Binding of ovarian cancer antigen CA125/MUC16 to mesothelin mediates cell adhesion

Mesothelin is a glycosylphosphatidylinositol-linked cell surface molecule expressed in the mesothelial lining of the body cavities and in many tumor cells. Based on the finding that a soluble form of mesothelin specifically binds to ovarian carcinoma cell line OVCAR-3, we isolated cDNAs encoding a mesothelin-binding protein by expression cloning. The polypeptides encoded by the two cloned cDNA fragments matched to portions of CA125, an ovarian cancer antigen and a giant mucin-like glycoprotein present at the surface of tumor cells. By flow cytometric analysis and immunoprecipitation, we demonstrate that CA125 binds to mesothelin in a specific manner. Binding of CA125 to membrane-bound mesothelin mediates heterotypic cell adhesion as anti-mesothelin antibody blocks binding of OVCAR-3 cells expressing CA125 to an endothelial-like cell line expressing mesothelin. Finally, we show that CA125 and mesothelin are co-expressed in advanced grade ovarian adenocarcinoma. Taken together, our data indicate that mesothelin is a novel CA125-binding protein and that CA125 might contribute to the metastasis of ovarian cancer to the peritoneum by initiating cell attachment to the mesothelial epithelium via binding to mesothelin.

Modulation of MUC1 and blood group antigen expression in gastric adenocarcinoma cells by cytokines

Immunohistological studies demonstrated that MUC1 expression in gastric cancer is associated with a poor prognosis. As a mediator of cell-cell interactions, MUC1 may also be involved in metastasis. However, these aspects are of relevance since cytokine levels are locally increased as a consequence of peritumorous inflammatory response and coexisting chronic gastritis. Therefore we analyzed the potential influence of several cytokines on the expression of tumor-associated MUC1 and Lewis blood group antigens in gastric carcinoma cells. Gastric cancer cell lines AGS and KATOIII were incubated with the cytokines interleukin-1beta, interferon-gamma, tumor necrosis factor-alpha (TNF-alpha), and hepatocyte growth factor over a period of 72 h. Expressions of mucin antigens and cytokine secretion were measured by immunocytochemistry and/or enzyme-linked immunosorbent assay (ELISA). Analysis by fluorescence-activated cell sorter (FACS) demonstrated that MUC1 and sialyl Lewis A reactivities of AGS cells were increased significantly following TNF-alpha stimulation but not by other cytokines. Expression of mucin-associated antigens by cell line KATOIII was not affected by any of the employed cytokines. These data provide evidence that TNF-alpha can raise the expression of important mucin peptide as well as mucin-associated carbohydrate antigens and thereby potentially influence the progression of gastric carcinomas.

Aberrant O-glycosylation inhibits stable expression of dysadherin, a carcinoma-associated antigen, and facilitates cell-cell adhesion

Recently, we identified dysadherin, a novel carcinoma-associated glycoprotein, and showed that overexpression of dysadherin in human hepatocarcinoma PLC/PRF/5 cells could suppress E-cadherin-mediated cell-cell adhesion and promote tumor metastasis. The present study shows evidence that dysadherin is actually O-glycosylated. This was based on a direct carbohydrate composition analysis of a chimera protein of an extracellular domain of dysadherin fused to an Fc fragment of immunoglobulin. To assess the importance of O-glycosylation in dysadherin function, dysadherin-transfected hepatocarcinoma cells were cultured in a medium containing benzyl-alpha-GalNAc, a modulator of O-glycosylation. This treatment facilitated homotypic cell adhesion among dysadherin transfectants accompanied with morphological changes, indicating that the anti-adhesive effect of dysadherin was weakened. Modification of O-glycan synthesis also resulted in down-regulation of dysadherin expression and up-regulation of E-cadherin expression in dysadherin transfectants but did not affect E-cadherin expression in mock transfectants. Structural analysis of O-glycans released from the dysadherin chimera proteins indicated that a series of O-glycans with core 1 and 2 structures are attached to dysadherin, and their sialylation is remarkably inhibited by benzyl-alpha-GalNAc treatment. However, sialidase treatment of the cells did not affect calcium-dependent cell aggregation, which excluded the possibility that sialic acid itself is directly involved in cell-cell adhesion. We suggest that aberrant O-glycosylation in carcinoma cells inhibits stable expression of dysadherin and leads to the up-regulation of E-cadherin expression by an unknown mechanism, resulting in increased cell-cell adhesion. The carbohydrate-directed approach to the regulation of dysadherin expression might be a new strategy for cancer therapy.

MUC-1 mucin protein expression in B-cell lymphomas

We have recently shown that MUC1, mapped to the chromosomal band 1q21, is rearranged or amplified in 15% of B-cell lymphomas and that rearrangement led to over-expression of MUC-1 mucin in a case of diffuse large B-cell lymphoma (DLBCL). To determine the incidence of MUC-1 mucin expression and its clinical significance in B-cell lymphomas, we investigated a panel of 113 cases by immunohistochemistry (IHC). MUC-1 mucin expression was detected in the majority of cases (92.9%), with moderate to high levels noted in 50.4% of all histologic subsets comprising DLBCL (82 cases), follicular lymphoma (FL) (15 cases), FL with transformation to DLBCL (4 cases), and other B-cell lymphomas (12 cases). No statistically significant correlation was found between MUC-1 mucin expression and MUC1 genomic status (amplification/rearrangement) evaluated by Southern blot analysis, and 1q21 abnormality by karyotypic analysis. For all cases, MUC-1 mucin expression correlated with a previous history of lymphoma (p=0.003).

Circulating anti-MUC1 IgG antibodies as a favorable prognostic factor for pancreatic cancer

MUC1 is immunogenic in vivo and humoral and cellular immune responses against MUC1 have been detected in cancer patients. Our study explored the association of circulating anti-MUC1 antibodies with clinicopathological parameters or patients' survival of pancreatic cancer. Serum specimens from 36 patients with invasive ductal carcinoma of the pancreas were subjected to enzyme immunoassay for anti-MUC1 IgG or IgM antibodies. Serum levels of anti-MUC1 IgG antibodies were significantly correlated with survival time (p = 0.0004), whereas neither those of anti-MUC1 IgM nor anti-Galalpha(1,3)Gal IgG antibodies, the latter known as natural antibodies cross-reactive with MUC1, showed a given tendency. Some patients' sera with the higher antibody titer showed the reactivity with MUC1-transfectants of cultured pancreatic cancer cells, but not with MUC1-negative parental cells. When the samples were tentatively divided into 2 groups by the serum level of anti-MUC1 IgG antibodies, the survival of patients was significantly longer in the group with optical density >or=0.3 than in that with optical density <0.3 (p = 0.008). Circulating anti-MUC1 IgG antibody levels remained significant (HR, 0.03; 95% CI, 0.003-0.289; p = 0.0024) after multivariate analysis for pTNM stage, patient age and gender. These data suggest that circulating anti-MUC1-IgG antibody levels may be predictive for survival of pancreatic cancer patients.

MUC1 expression is correlated with nuclear grade and tumor progression in pT1 renal clear cell carcinoma

We studied, by immunohistochemical analysis, the expression of MUC1 and epithelial membrane antigen in 44 stage pT1 renal cell carcinomas (RCCs). Six patients had a metastatic evolution. The percentage of stained cells was determined for each tumor. All tumors and normal adjacent renal parenchyma were stained. In normal kidney, distal convoluted tubules and collecting ducts stained strongly with an apical distribution. In tumors, there was a significant statistical correlation of the MUC1 expression level with the nuclear grade and with tumor progression. High-grade tumors had more stained cells than did low-grade tumors. Metastatic tumors also were more stained than nonmetastatic lesions. By using the Kaplan-Meier method and the log-rank test, we observed that patients with fewer than 10% of stained cells had no metastatic evolution. In contrast, patients with 70% or more stained cells had significantly lower metastasis-free survival rates. We conclude that MUC1 is expressed in RCC and is associated with tumor progression in pT1 RCC.

The expression of human FUT1 in HT-29/M3 colon cancer cells instructs the glycosylation of MUC1 and MUC5AC apomucins

Recently, we have reported that in normal gastric epithelium, the expression of gastric apomucins MUC5AC and MUC6 is associated with the specific expression of type 1 and type 2 Lewis antigens, and FUT2 and FUT1 fucosyltransferases, respectively. Until now, there are no data demonstrating the direct implication of specific glycosyltransferases in the specific patterns of apomucin glycosylation. HT29/M3 colon cancer cell line express MUC1, MUC5AC, type 1 Lewis antigens and FUT2 but not type 2 structures and FUT1, as it occurs in the epithelial cells of the gastric superficial epithelium. These cells were transfected with the cDNA of human FUT1, the alpha-1,2-fucosyltransferase responsible for the synthesis of type 2 Lewis antigens, to assess the implication of FUT1 in the glycosylation of MUC1 and MUC5AC. The M3-FUT1 clones obtained express high levels of type 2 Lewis antigens: H type 2 and Ley antigens. Immunoprecipitation of MUC1 and MUC5AC apomucins gives the direct evidence that FUT1 catalyses the addition of alpha-1,2-fucose to these apomucins, supporting the hypothesis that the pattern of apomucin glycosylation is not only instructed by the mucin primary sequence but also by the set of glycosyltransferases expressed in each specific cell type.

Characterization of human mucin gene MUC4 promoter: importance of growth factors and proinflammatory cytokines for its regulation in pancreatic cancer cells

The human mucin gene MUC4 encodes a large transmembrane mucin that is thought to play important roles in tumor cell biology and that is overexpressed in human pancreatic carcinomas. In this report, we describe the structure and functional activity of the 5'-flanking region, including 1.0 kilobase of the promoter. The long 5'-untranslated region (2.7 kilobases) is characterized by a high content of GC in its 3'-end. The first TATA box was located at -2672/-2668. Multiple transcription start sites and a high density of putative binding sites for Sp1 (GC and CACCC boxes), AP-1/-2/-4, cAMP-responsive element-binding protein, GATA, GR, and STAT transcription factors were found within the 5'-flanking region. Transcriptional activity of the promoter was assessed using pGL3-luciferase deletion mutants in two MUC4-expressing (CAPAN-1 and CAPAN-2) and one nonexpressing (PANC-1) pancreatic cancer cell line. Two highly active fragments (-219/-1 and -2781/-2572) that drive MUC4 transcription in CAPAN-1 and CAPAN-2 cells were identified. Gel retardation assays indicated that Sp1 and Sp3 bind to cognate cis-elements found in the 5'-flanking region and that Sp1 transactivates, whereas Sp3 inhibits the GC-rich region (-464/-1) in CAPAN-2 cells. Activation of protein kinase C with phorbol ester and treatment of cells with epidermal growth factor and transforming growth factor-alpha resulted in up-regulation of the promoter. Tumor necrosis factor-alpha and interferon (IFN)-gamma inflammatory cytokines had no or mild effect on MUC4 transcriptional activity when used alone. However, a very strong synergistic effect (10-12-fold activation) between IFN-gamma and tumor necrosis factor-alpha or IFN-gamma and transforming growth factor-alpha was obtained in CAPAN-2 cells. Altogether these results demonstrate that the 5'-flanking region of MUC4 contains epithelial cell-specific, positive, and negative regulatory cis-elements, that Sp1/Sp3 are important regulators of MUC4 basal expression, and that its regulation in pancreatic cancer cells involves complex interplay between several signaling pathways.

Human MUC1 mucin: a potent glandular morphogen

Human MUC1 mucin is a high-molecular-weight transmembrane glycoprotein, which is apically expressed in the majority of glandular epithelia. During embryonic development, changes in the pattern of MUC1 mucin expression coincide with the onset of glandular differentiation. This mucin is also frequently overexpressed and aberrantly glycosylated in carcinomas. To investigate the potential role of MUC1 mucin in morphogenesis, a full length MUC1 cDNA was transfected into murine mammary adenocarcinoma (410.4) and Madin-Darby canine kidney (MDCK) cells. This generated four clonal cell lines. Western blotting, FACS analysis, and immunohistochemistry confirmed expression of MUC1. All four MUC1-expressing clones demonstrated altered morphogenesis when cultured in three-dimensional type I collagen gels. While parental and vector control 410.4 cells formed compact spherical structures, the MUC1-expressing clones formed complex branching structures. Similarly, while parental and vector control MDCK cells formed small circumscribed colonies with a central lumen, the MUC1-expressing clones formed elongated tubules. MUC1 expression was also associated with reduced cellular cohesion and enhanced migration on type I collagen-coated surfaces for all except one of the clones, which expressed only low levels of MUC1 on the cell surface. These results show that MUC1 expression stimulates morphogenetic changes in two distinct epithelial cell lines. Taken together with previous observations on MUC1 expression in embryonic development and carcinomas, this finding suggests that MUC1 may induce changes in tissue architecture in both normal development and cancer.

MUC1, the renaissance molecule

MUC1 is a large, heavily glycosylated mucin expressed on the apical surfaces of most simple, secretory epithelia including the mammary gland, gastrointestinal, respiratory, urinary and reproductive tracts. Although MUC1 was thought to be an epithelial-specific protein, it is now known to be expressed on a variety of hematopoietic cells as well. Mucins function in protection and lubrication of epithelial surfaces. Transmembrane mucins, which contain cytoplasmic tail domains, appear to have additional functions through their abilities to interact with many proteins involved in signal transduction and cell adhesion. The goal of this review is to highlight recent discoveries that suggest that MUC1 may be a multifunctional protein, located on the surfaces of cells as a sensor of the environment, poised to signal to the interior when things go awry.