Heterogeneous expression of tumor-associated genes in disseminated breast cancer cells

BACKGROUND

Gene expression profiles were determined to demonstrate heterogeneity of viable disseminated tumor cells (DTC) in the blood of breast cancer patients.

PATIENTS AND METHODS

All patients (n = 48) suffered from metastatic disease (M1) and were treated with chemotherapy and/or Herceptin, respectively. Blood samples were analyzed by a DTC detection assay consisting of immunomagnetic tumor cell selection combined with expression profiling of the tumor-associated transcripts GA733-2, MUC-1, HER-2 and Claudin-7. In addition, the correlation of HER-2 expression in DTC with histopathologically determined HER-2 status in distant metastases and primary tumors in selected cases was investigated.

RESULTS

DTC were detected in 69% (p < 0.0001) of breast cancer patients. The expression profiles were shown to be heterogeneous within different patients and even within the follow-up period of patients, reflecting the expected heterogeneity of DTC. Furthermore, preliminary results showed a correlation between HER-2 gene expression in DTC and HER-2 overexpression in tumor tissue of distant metastases.

CONCLUSION

The results suggest a clinical value of the DTC detection assay with respect to a more precise characterization of individual cancer disease and selection for therapy. More emphasis should be placed on HER-2 expression in DTC as a possible precursor of distant metastases.

Characteristic Ber-EP4 and EMA expression in sebaceoma is immunohistochemically distinct from basal cell carcinoma

AIMS

There is considerable overlap between the histological features of sebaceoma and basal cell carcinoma (BCC). The distinction between these two tumours is important due to the often more locally aggressive nature of BCC and the association of sebaceoma with the Muir-Torre syndrome. The aim of this study was to describe the immunohistochemical reactivity of the cells in sebaceoma to Ber-EP4 and epithelial membrane antigen (EMA) and investigate the utility of this panel to differentiate sebaceoma from basal cell carcinoma.

METHODS AND RESULTS

Immunohistochemistry of 25 sebaceomas for Ber-EP4 and EMA revealed unequivocal negative expression of Ber-EP4 in 24 of 25 sebaceomas. A single case exhibited focal weak Ber-EP4 staining, predominantly in mature sebocytes and in < 10% of the tumour cells. EMA was not expressed in the germinative cells of sebaceoma, but was expressed strongly in approximately 50% of mature sebocytes in all cases and highlighted the cytoplasmic vacuoles. We reviewed the immunoreactivity of 51 cases of nodular BCCs and found moderate or strong BerEP4 expression in all cases with never less than 20% of the tumour staining. Expression of EMA was uncommon in BCC (moderate or strong in 8%) and was confined to keratotic or squamoid areas.

CONCLUSION

The use of Ber-EP4 in combination with EMA, both widely used immunomarkers in histopathology, is a helpful aid in distinguishing sebaceoma from nodular BCC.

The signaling pathway involved in neutrophil elastase stimulated MUC1 transcription

We previously reported that neutrophil elastase (NE) stimulated MUC1 gene expression in A549 lung epithelial cells through binding of Sp1 to the MUC1 promoter element. The current study was undertaken to elucidate the complete signaling pathway leading to Sp1 activation. Using a combination of pharmacologic inhibitors, dominant-negative mutant, RNA interference, and soluble receptor blocking techniques, we identified a protein kinase Cdelta (PKCdelta) --> dual oxidase 1 (Duox1) --> reactive oxygen species (ROS) --> TNF-alpha-converting enzyme (TACE) --> TNF-alpha --> TNF receptor (TNFR)1 --> extracellular signal-regulated kinase (ERK)1/2 --> Sp1 pathway as responsible for NE-activated MUC1 transcription. This cascade was identical up to the point of TACE with the signaling pathway previously reported for NE-stimulated MUC5AC production. However, unlike the MUC5AC pathway, TNF-alpha, TNFR1, ERK1/2, and Sp1 were unique components of the MUC1 pathway. Given the anti-inflammatory role of MUC1 during airway bacterial infection, up-regulation of MUC1 by inflammatory mediators such as NE and TNF-alpha suggests a crucial role for MUC1 in the control of excessive inflammation during airway bacterial infection.

Downregulated P1 promoter-driven hepatocyte nuclear factor-4alpha expression in human colorectal carcinoma is a new prognostic factor against liver metastasis

Liver metastases are the most critical prognostic factors for patients with colorectal carcinomas (CRC). It has been reported that the dysregulation of hepatocyte nuclear factor-4alpha (HNF4alpha) expression is linked to the development of CRC, gastric cancer and hepatocellular carcinoma. The purpose of the present paper was to examine the P1 and P2 promoter-driven HNF4alpha (P1 and P2) expression in surgically resected CRC. Immunohistochemically, P1, P2, MUC1 and CD10 expression were evaluated in 63 cases of primary CRC. Positive staining with P1, P2, MUC1 and CD10 antibodies were observed in 37 (59%), 63 (100%), 42 (67%) and 27 (43%) cases, respectively. Loss or decreased P1 expression was observed with respect to the depth of the tumor invasion. The frequency of P1-positive expression in Dukes' C and D tumors was significantly lower than that in Dukes' A and B tumors. There was a relationship between the loss of P1 expression and metachronous liver metastases, and the survival rate of the P1-negative patients without liver metastasis at the time of the primary CRC resection tended to be worse than that of the P1-positive patients. These findings suggest that downregulation of P1 expression is involved in tumor metastasis and a worse prognosis.

Multi-layered culture of primary human conjunctival epithelial cells producing MUC5AC

The purpose of our study was to establish a system for culturing normal human conjunctival epithelial (NHCE) cells under serum-free culture conditions without compromising their ability to differentiate into a mucous epithelium. To this end, small pieces of normal conjunctiva were biopsied from patients undergoing cataract surgery. Obtained NHCE cells were cultured in bronchial epithelial growth medium (BEGM) under serum free culture conditions and passage 3 cells were air-lifted. Cultured NHCE cells displayed typical epithelial morphology. Expression of cytokeratin 19 and conjunctival epithelial specific carbohydrate residue were detected. Air-lifted NHCE cells demonstrated an increase in stratification and differentiation into goblet cells up to 3weeks under air-liquid interface (ALI) culture condition. NHCE cells expressed MUC1, MUC4, MUC16, and MUC5AC mRNA, and MUC5AC production and secretion increased in a time dependent manner after culture under ALI conditions. Exposure of cells to proinflammatory cytokines (TNF-alpha or IFN-gamma) resulted in upregulation of MUC1, MUC4, MUC16, and MUC5AC gene expression. In conclusion, differentiated NHCE cells showed features of a multi-layered conjunctival epithelium, including goblet cells, and retained functional characteristics similar to those seen in vivo. This cell culture system can better facilitate investigation of conjunctival epithelial cell biology and goblet cell differentiation.

Analysis of the sheep MUC1 gene: structure of the repetitive region and polymorphism

An investigation was undertaken with the aim of studying the repetitive region of the MUC1 gene and analyzing its polymorphisms in some Italian sheep breeds. Two primers previously used for the goat MUC1 gene analyses allowed for the amplification of 4 different alleles. The sequence analysis showed that the repetitive region of the sheep MUC1 gene is an array of 60-bp repeats, in accordance with the information reported in humans, cattle, and goats. The polypeptide sequence encoded by the consensus repeat was very similar to the corresponding sequences of goats and cattle. The average homology of all repeated units was 82%; when the repeats were compared with the derived consensus repeat, homology dropped to 78%. The repeats were not all perfectly conserved, but the sequence homology was nevertheless clearly sufficient to preserve the mechanism giving rise to the variable-number tandem-repeat polymorphism. In spite of their reduced sequence homology, the sheep repeats shared a high number of potential glycosylation sites. The conservation of the exact number and position of glycosylation sites did not seem to be very important for the purpose of functional integrity, but glycosylation appeared to be conserved as a bulk property. Analysis of the polymorphism in 6 Italian breeds showed that the sheep repetitive region seemed to be less variable and smaller in size than the repetitive region of the goat. The findings of this study suggest that ruminants can be a useful model to study the mechanisms by which the variation in the repeat number and the extracellular domain size can modulate the effectiveness of MUC1 as a cell-surface shield.

S-layer-mediated display of the immunoglobulin G-binding domain of streptococcal protein G on the surface of Caulobacter crescentus: development of an immunoactive reagent

The immunoglobulin G (IgG)-binding streptococcal protein G is often used for immunoprecipitation or immunoadsorption-based assays, as it exhibits binding to a broader spectrum of host species IgG and IgG subclasses than the alternative, Staphylococcus aureus protein A. Caulobacter crescentus produces a hexagonally arranged paracrystalline protein surface layer (S-layer) composed of a single secreted protein, RsaA, that is notably tolerant of heterologous peptide insertions while maintaining the surface-attached crystalline character. Here, a protein G IgG-binding domain, GB1, was expressed as an insertion into full-length RsaA on the cell surface to produce densely packed immunoreactive particles. GB1 insertions at five separate sites were expressed, and all bound rabbit and goat IgG, but expression levels were reduced compared to those of wild-type RsaA and poor binding to mouse IgG was noted. To remedy this, we used the 20-amino-acid Muc1 peptide derived from human mucins as a spacer, since insertions of multiple tandem repeats were well tolerated for RsaA secretion and assembly. This strategy worked remarkably well, and recombinant RsaA proteins, containing up to three GB1 domains, surrounded by Muc1 peptides, not only were secreted and assembled but did so at wild-type levels. The ability to bind IgG (including mouse IgG) increased as GB1 units were added, and those with three GB1 domains bound twice as much rabbit IgG per cell as S. aureus cells (Pansorbin). The ability of recombinant protein G-Caulobacter cells to function as immunoactive reagents was assessed in an immunoprecipitation assay using a FLAG-tagged protein and anti-FLAG mouse monoclonal antibody; their performance was comparable to that of protein G-Sepharose beads. This work demonstrates the potential for using cells expressing recombinant RsaA/GB1 in immunoassays, especially considering that protein G-Caulobacter cells are more cost-effective than protein G beads and exhibit a broader species and IgG isotype binding range than protein A.

The polymorphism in MUC1 gene in Nelore cattle

MUC1 is a transmembrane glycoprotein expressed on the apical surfaces of the uterine epithelial tissue with predicted functions in protection and cell-cell adhesion. These properties are closely related with the repetitive region [variable number of tandem repeats (VNTR)] of the extracellullar domain and with the O-glycosylation in their serine and threonine residues. This study describes a polymerase chain reaction (PCR) protocol to analyse MUC1 bovine genetic polymorphism and demonstrates the existence of a VNTR within the sites for O-glycosylation. Oligonucleotide primers based on the Bos taurus mucin (MUC1) gene sequence GenBank AF399757 were used to amplify five VNTR MUC1 alleles from a study group of 56 pure Nelore bovines. The number of repeats varied between 10 and 24, being more prevalent than the alleles with less number of repeats. The DNA sequence analysis revealed two repeats and one of them presented 100% homology with the bovine consensus sequence already reported. The second repeat showed codons that translate to serine and proline amino acids, which are conserved in the MUC1 of several species. This study is the first description of allelic variation and the VNTR structure in the Nelore breed MUC1 gene, and we suggest that this genetic variability can be tested for association with variation in reproductive traits in Nelore cattle.

[Enhancement of HSP-MUC1 antitumor activity by type C CpG-ODN BW005]

AIM

To investigate the enhancement of anti-tumor effect of HSP-MUC1 by self-designed type C CpG-ODN BW005.

METHODS

The immunostimulatory effect of CpG-ODN BW005 was detected by IFN protection assay and (3)H proliferation assay in vitro. Sixty C57BL/6 mice were separated into 5 groups randomly, including Sodium Chloride control, HSP-MUC1 control, HSP-MUC1/1585, HSP-MUC1/1826 and HSP-MUC1/BW005. Mice were injected s.c. with agents on day 0, 14 and 28 and were implanted MUC1-EL4 tumor cells s.c. on day 33. Tumor growth and murine death were recorded. Blood was collected in 57 day from tail vein. Subtype of anti-HSP and anti-MUC1 IgG in serum was detected by indirect ELISA.

RESULTS

CpG-ODN BW005 could stimulate the proliferation of hPBMC and mice spleoncyte and IFNalpha production. HSP-MUC1/BW005 postponed tumor development, with the average tumor-developed day of 44.8, and prolonged the survival of mice with the average survival day of 49.5. Moreover, final tumor-developed rate of this group was 33.33%, which was the lowest; final survival rate of this group was 66.67%, which was the highest. Levels of anti-HSP and anti-MUC1 IgG2a in HSP-MUC1/CpG-ODNs group were enhanced.

CONCLUSION

CpG-ODN BW005, a kind of type C CpG-ODN, could enhance the anti-tumor effect of HSP-MUC1.

Intramolecular antigenicity of MUC1, a candidate for cancer vaccines

Cancer is a big public health problem as well as a medical challenge. The tumor-associated carbohydrate antigens and glycopeptide antigens derived from, for example, the MUC1 mucin glycoprotein or tumor mucin antigen, are attractive targets for the immunotherapy of cancer, owing to their expression by malignant cells. MUC1 glycoprotein is present in endometriotic lesions and over-expressed in many cancers and the MUC1 immune response is known to provide a protective host defense mechanism against cancer. In this work, the author studied the antigenicity pattern within the MUC1 molecule by an advanced bioinformatics method. It can be seen that the amino acid in the middle portion of the sequence pose high antigenicity. This part could be selected for further vaccine development.

The role of MUC1 and MUC3 in the biology and prognosis of colorectal cancer

Background

MUC1 and MUC3 are from a large family of glycoproteins with an aberrant expression profile in various malignancies. Much interest has been focused on the role of these proteins in the development and progression of colorectal cancer; however, no previous studies have included the highly confounding variable of vascular invasion in their survival analysis. Using high throughput tissue microarray technology we assessed the prognostic value of MUC1 and MUC3 expression in the largest cohort of colorectal cancer patients to date. We propose that tumours lacking expression of MUC1 and MUC3 will be more likely to metastasise, due to previously observed loss of cell-cell adhesion, and this will therefore lead to more aggressive cancers with poorer prognosis.

Methods

A tissue micro-array was prepared from tumour samples of 462 consecutive patients undergoing resection of a primary colorectal cancer. A comprehensive prospectively recorded data base with mean follow up of 75 months was collected and included common clinicopathological variables and disease specific survival. Immunohistochemical analysis of MUC1 and MUC3 expression was performed using antibodies NCL-MUC1 and 1143/B7 respectively, results were correlated with the variables within the database.

Results

Positive expression of MUC1 and MUC3 was seen in 32% and 74% of tumours respectively. On univariate analysis no correlation was seen with either MUC1 or MUC3 and any of the clinicopathological variables including tumour grade and stage, vascular invasion and tumour type. Kaplan-Meier analysis demonstrated a significant reduction in disease specific survival with MUC1 positive tumours (p = 0.038), this was not seen with MUC3 (p = 0.552). On multivariate analysis, using Cox proportional hazards model, MUC1 expression was shown to be an independent marker of prognosis (HR 1.339, 95%CI 1.002–1.790, p = 0.048).

Conclusion

MUC1 expression in colorectal cancer is an independent marker of poor prognosis, even when vascular invasion is included in the analysis. These results support previous studies suggesting a role for MUC1 in colorectal cancer development possibly through its effects on cell adhesion.

Clinical significance of detecting mucin 1 mRNA in diagnosing occult lymph node micrometastasis in esophageal cancer patients

BACKGROUND & OBJECTIVE

Early postoperative relapse in esophageal cancer might be related to occult lymph node micrometastasis that could not be detected by routine histopathologic examination. This study was to investigate the clinical significance of detecting Mucin 1 (MUC1) mRNA in diagnosing occult lymph node micrometastasis in esophageal cancer patients, and to evaluate its prognostic significance.

METHODS

The expression of MUC1 mRNA in 366 regional lymph nodes from 63 esophageal squamous cell cancer (ESCC) patients without histopathologically confirmed invasion (pN0), 30 paraesophageal lymph nodes from patients with benign esophageal diseases, and 15 lymph nodes and 15 tumor tissues from ESCC patients with histopathologically proved metastasis (pN1) were detected by reverse transcription-polymerase chain reaction (RT-PCR) to determine micrometastasis. Survival difference was compared by Chi(2) test. Logistic regression analysis was performed to assess independent prognostic factors.

RESULTS

Specificity of genetic diagnosis was 100.0% (30/30) for occult lymph node micrometastasis, and 90.0% (27/30) for lymph node micrometastasis. MUC1 mRNA was identified in 30 (8.2%) lymph nodes from 22 (34.9%) patients. Occult lymph node micrometastasis was diagnosed in these patients. The 3-year survival rate was significantly lower in the patients with lymph node micrometastasis than in the patients without lymph node micrometastasis (54.5% vs. 80.5%, P<0.01). In Logistic regression analysis, lymph node micrometastasis (P<0.05, odds ratio=3.71) and T3 tumor (P<0.05, odds ratio=7.17) were independent prognostic factors.

CONCLUSIONS

It is helpful to diagnose occult lymph node micrometastasis by detecting the expression of MUC1 mRNA in lymph nodes of pN0 ESCC patients. Lymph node micrometastasis may predict poor prognosis of the patients after radial operation.

Intradermal vaccination of MUC1 transgenic mice with MUC1/IL-18 plasmid DNA suppresses experimental pulmonary metastases

MUC1 (mucin 1) is a transmembrane glycoprotein normally expressed on epithelia of the pancreas, breast, prostate, colon, and lung. However, this self-antigen is over-expressed and aberrantly glycosylated in adenocarcinomas, thereby making it a potential target for immunotherapy. Toward this goal, DNA plasmids encoding human MUC1 (pMUC1) and mouse interleukin-18 (pmuIL-18) were developed, and previous work demonstrated pMUC1/pmuIL18 vaccination protected MUC1 transgenic mice (MUC1.Tg) from subcutaneous tumor challenge. This report shows that pMUC1/pmuIL-18 is effective in preventing and treating pulmonary metastases in MUC1.Tg mice. Vaccination with pMUC1 or pmuIL-18 alone was insufficient to elicit measurable anti-tumor effects. However, co-administration of pMUC1 with pmuIL-18 reduced the incidence of lung tumors and prolonged survival. Furthermore, pMUC1/pmuIL-18 immunization protected mice from challenge with MUC1+ tumors, but not from MUC1- tumors, indicating that the anti-tumor effect is antigen-specific. More importantly, pMUC1/pmuIL-18 was effective in treating established tumors. Finally, in vivo antibody-mediated lymphocyte depletion and neutralization of interferon gamma (IFNgamma) revealed that CD8+ T cells and IFNgamma mediate the anti-tumor immunity. Collectively, these results demonstrate that pMUC1/pmuIL-18 breaks tolerance to MUC1, and induces antigen-specific immunity with protective and therapeutic benefit. This suggests that pMUC1/pmuIL-18 DNA vaccination may provide clinical benefit for patients with MUC1+ tumors.

Enhanced major histocompatibility complex class I binding and immune responses through anchor modification of the non-canonical tumour-associated mucin 1-8 peptide

Designing peptide-based vaccines for therapeutic applications in cancer immunotherapy requires detailed knowledge of the interactions between the antigenic peptide and major histocompatibility complex (MHC) in addition to that between the peptide-MHC complex and the T-cell receptor. Past efforts to immunize with high-affinity tumour-associated antigenic peptides have not been very immunogenic, which may be attributed to the lack of T cells to these peptides, having been deleted during thymic development. For this reason, low-to-medium affinity non-canonical peptides represent more suitable candidates. However, in addition to the difficulty in identifying such antigens, peptide binding to MHC, and hence its ability to induce a strong immune response, is limited. Therefore, to enhance binding to MHC and improve immune responses, anchor modifications of non-canonical tumour-associated peptides would be advantageous. In this study, the non-canonical tumour-associated peptide from MUC1, MUC1-8 (SAPDTRPA), was modified at the MHC anchor residues to SAPDFRPL (MUC1-8-5F8L) and showed enhanced binding to H-2Kb and improved immune responses. Furthermore, the crystal structure of MUC1-8-5F8L in complex with H-2Kb was determined and it revealed that binding of the peptide to MHC is similar to that of the canonical peptide OVA8 (SIINFEKL).

MUC1/X protein immunization enhances cDNA immunization in generating anti-MUC1 alpha/beta junction antibodies that target malignant cells

MUC1 has generated considerable interest as a tumor marker and potential target for tumor killing. To date, most antibodies against MUC1 recognize epitopes within the highly immunogenic alpha chain tandem repeat array. A major shortcoming of such antibodies is that the MUC1 alpha chain is shed into the peripheral circulation, sequesters circulating antitandem repeat array antibodies, and limits their ability to even reach targeted MUC1-expressing cells. Antibodies recognizing MUC1 epitopes tethered to the cell surface would likely be more effective. MUC1 alpha subunit binding the membrane-tethered beta subunit provides such an epitope. By use of a novel protocol entailing immunization with cDNA encoding full-length MUC1 (MUC1/TM) followed by boosting with the alternatively spliced MUC1/X isoform from which the tandem repeat array has been deleted, we generated monoclonal antibodies, designated DMC209, which specifically bind the MUC1 alpha/beta junction. DMC209 is exquisitely unique for this site; amino acid mutations, which abrogate MUC1 cleavage, also abrogate DMC209 binding. Additionally, DMC209 specifically binds the MUC1 alpha/beta junction on full-length MUC1/TM expressed by breast and ovarian cancer cell lines and on freshly obtained, unmanipulated MUC1-positive malignant plasma cells of multiple myeloma. DMC209 is likely to have clinical application by targeting MUC1-expressing cells directly and as an immunotoxin conjugate. Moreover, the novel immunization procedure used in generating DMC209 can be used to generate additional anti-MUC1 alpha/beta junction antibodies, which may, analogously to Herceptin, have cytotoxic activity. Lastly, sequential immunization with MUC1/TM cDNA acting as a nonspecific adjuvant followed by protein of interest may prove to be a generalizable method to yield high-titer specific antibodies.

Hidradenocarcinoma: a histological and immunohistochemical study

The diagnosis of hidradenocarcinoma is difficult due to a combination of factors including inconsistent nomenclature/ classification, rarity of the neoplasm, and variable morphology of cells composing the neoplasm. Immunohistochemistry has not been previously performed on a series of hidradenocarcinomas. We evaluated six cases of hidradenocarcinoma histologically and immunohistochemically using antibodies to gross cystic disease fluid protein-15 (GCDFP-15), carcino-embryonic antigen (CEA), epithelial membrane antigen (EMA), S-100 protein, keratin AE1/3, cytokeratin 5/6, p53, bcl-1, bcl-2, and Ki67. Histology suggested concurrent eccrine and apocrine differentiation of the cases. Ki67 and p53 staining was strongly positive in five of six tumors. The neoplasms stained with antibodies to CEA, S-100 protein, GCDFP-15, EMA, bcl-1, and bcl-2 in no consistent pattern. All tumors studied stained positively for keratin AE1/3 and cytokeratin 5/6. In making the diagnosis of hidradenocarcinoma, it may be unnecessary to separate hidradenocarcinoma into eccrine and apocrine categories, and although Ki67 and p53 may be helpful, histological parameters remain paramount.

[Construction and expression of eukaryotic coexpression plasmid containing human MUC1 gene and GM-CSF gene]

AIM

To construct an eukaryotic coexpression plasmid containing the coding region of human MUC1 tandem repeats gene and GM-CSF gene and to identify its expression in COS-7 cell.

METHODS

MUC1 tandem repeats gene was obtained by synthesizing the segments. After identified by restriction endonuclease digestion analysis and DNA sequencing, MUC1 tandem repeats gene and GM-CSF gene were cloned into eukaryotic expression vector pcDNA3.1(+) to construct recombinant plasmid pcDNA3.1(+)-MUC1-GM-CSF. Then the recombinant plasmid was transfected into COS-7 cell by electroporation and the expression of target gene was detected by immunoflourescence and ELISA.

RESULTS

Restriction analysis and DNA sequencing showed that the recombinant plasmid contained the coding region of human MUC1 tandem repeats gene and GM-CSF gene. The expression of MUC1 and GM-CSF was detected.

CONCLUSION

The suuessful construction and expression of recombinant plasmid pcDNA3.1(+)-MUC1-GM-CSF lay a foundation for further development of DNA vaccine against breast cancer.

The VSL#3 probiotic formula induces mucin gene expression and secretion in colonic epithelial cells

Several studies have stressed the importance of the microbiota in the maintenance of the gastrointestinal epithelium. Administration of probiotic bacteria, supplements composed of microbiota constituents, was previously shown to diminish symptoms in patients suffering from inflammatory bowel diseases. This raises the possibility that probiotics may play an active role in enhancing the intestinal barrier at the mucosal surface. In this study, we investigated whether the clinically tested VSL#3 probiotic formula and/or its secreted components can augment the protective mucus layer in vivo and in vitro. For in vivo studies, Wistar rats were orally administered the probiotic mixture VSL#3 on a daily basis for seven days. After treatment, basal luminal mucin content increased by 60%. In addition, we exposed isolated rat colonic loops to the VSL#3 probiotic formula, which significantly stimulated colonic mucin (MUC) secretion and MUC2 gene expression; however, MUC1 and MUC3 gene expression were only slightly elevated. The effect of the VSL#3 mucin secretagogue was also tested in vitro by use of LS 174T colonic epithelial cells. In contrast to the animal studies, cultured cells incubated with VSL#3 bacteria did not exhibit increased mucin secretion. However, the bacterial secreted products contained in the conditioned media stimulated a remarkable mucin secretion effect. Among the three bacterial groups (Lactobacilli, Bifidobacteria, and Streptococci) contained in VSL#3, the Lactobacillus species were the strongest potentiator of mucin secretion in vitro. A preliminary characterization of the putative mucin secretagogue suggested that it was a heat-resistant soluble compound, which is not sensitive to protease and DNase treatment. These findings contribute to a better understanding of the complex and beneficial interaction between colonic epithelial cells and intestinal bacteria.

Human sodium iodide symporter gene adjunctive radiotherapy to enhance the preventive effect of hMUC1 DNA vaccine

We demonstrate the use of combination therapy to overcome the limitations of cancer DNA vaccines by adding radioiodine gene therapy in an animal cancer model. We established a stable cell line (CT26/hMUC1-hNIS-Fluc: CMNF) expressing the hMUC1, hNIS and Fluc genes using a retro- and lentivirus system. The survival rates (%) of CMNF cells were determined using clonogenic assays after (131)I treatment. After i.m. immunization to 4 groups of Balb/c mice (pcDNA3.1, pcDNA3.1+(131)I, pcDNA3-hMUC1+PBS and pcDNA3-hMUC1+(131)I groups) with pcDNA3-hMUC1 or pcDNA3.1 once a week for 2 weeks, 1 x 10(5) CMNF cells were injected s.c. into the right thighs of mice in each group. Twenty-one days after tumor transplantation, (131)I was administered i.p. to the pcDNA3.1+(131)I and pcDNA3-hMUC1+ (131)I groups. Tumor progression was monitored in the 4 groups by bioluminescent and scintigraphic imaging and by taking caliper measurements. Tumor masses were extracted and weighted at 39 days post-tumor challenge. We confirmed that CMNF cells highly express hMUC1, hNIS and Fluc by FACS, (125)I uptake, and luciferase assay. The survival rates of CMNF were markedly reduced to (14.6 +/- 1.5)% after (131)I treatment compared with the survival rates of parental cells (p < 0.001). Tumor growth inhibition was significant only in the pcDNA3-hMUC1+ (131)I group at 39 days post challenge. Tumor masses in pcDNA3-hMUC1+ (131)I group were smaller than those of the other groups. This study shows that the weak preventive effects of cancer DNA vaccine can be overcome by radioiodine gene therapy utilizing sodium iodide symporter.

The cytoplasmic expression of MUC1 in papillary thyroid carcinoma of different histological variants and its correlation with cyclin D1 overexpression

This study addressed the immunohistochemical expression of MUC1 in papillary thyroid carcinoma (PTC) of different histotypes, sizes, and morphological features of aggressiveness, and its correlation with the overexpression of cyclin D1, a target molecule of the Wnt pathway. MUC1 expression was examined in a total of 209 PTCs. Cytoplasmic MUC1 expression was elevated in the tall, columnar cell and oncocytic variants (100%), Warthin-like (78%), and conventional PTCs (61%), and in papillary microcarcinoma (PMC) with the conventional growth pattern (52%). On the contrary, it was low in the follicular variant (27%) of PTC and PMCs with follicular architecture (13%). Cytoplasmic MUC1 accumulation did not associate with any clinicopathological features except peritumoral lymphoid infiltration in PTCs and in PMCs with the conventional growth pattern. MUC1 staining correlated with cyclin D1 overexpression in conventional PTCs and PMCs and PMCs with follicular architecture. The results demonstrate that MUC1 expression varies broadly in different histological variants of PTC, being the lowest in tumors with follicular structure. In general, it does not prove to be a prognosticator of PTC aggressiveness. A high correlation between MUC1 and cyclin D1 implies MUC1 involvement in the Wnt cascade functioning in a large subset of human PTCs and PMCs.

Alterations of the ocular surface epithelial mucins 1, 2, 4 and the tear functions in patients with atopic keratoconjunctivitis

BACKGROUND

An increased understanding of the ocular surface alterations at the cellular level in the conjunctiva and the cornea, may help explain the pathogenesis and the subsequent clinical appearance of atopic ocular allergies, which may be potentially blinding.

PURPOSE

To investigate MUC 1, 2 and 4 alterations, tear function and the ocular surface disorder in patients with atopic keratoconjunctivitis.

METHODS

Twenty-eight eyes of 14 atopic keratoconjunctivitis patients as well as 22 eyes of 11 age-and sex-matched normal subjects were studied. The subjects underwent corneal sensitivity measurements, Schirmer's test, tear film break-up time (BUT), fluorescein and Rose Bengal staining of the ocular surface, conjunctival impression cytology and brush cytology. Impression cytology samples underwent periodic acid-Schiff and immunohistochemical staining with MUC 1, 2 and 4 antibodies. Brush cytology specimens underwent evaluation for inflammatory cell numbers and quantitative real-time-PCR for MUC 1, 2 and 4 mRNA expression. Patient eyes with fluorescein and Rose Bengal scores greater than four points were regarded to have significant epithelial disease in this study.

RESULTS

The mean corneal sensitivity and BUT values were significantly lower in atopic patients with significant epithelial disease, compared with patients with insignificant epithelial disease and controls (P < 0.01). Brush cytology specimens from patients with significant epithelial disease revealed significantly higher numbers of inflammatory cells (P < 0.01). Specimens from patient eyes showed positive staining for MUC 1, 2 and 4. MUC 1, 2 and 4 mRNA expressions were significantly higher in eyes with significant epithelial disease compared with eyes with insignificant epithelial disease and eyes of control subjects.

CONCLUSION

Ocular surface inflammation, decline in corneal sensitivity, tear film instability, changes in conjunctival epithelial MUC 1, 2 and 4 mRNA expressions were thought to be important in the pathogenesis of atopic ocular surface disease.

Mucin genes have different expression patterns in healthy and diseased upper airway mucosa

BACKGROUND

Mucus hyper-secretion is a feature of several airways diseases such as chronic rhinosinusitis, asthma, and cystic fibrosis (CF). Since mucins are major components of mucus, the knowledge of their distribution and regulation in nasal tissues is likely to improve mucus hyper-secretion therapy.

OBJECTIVE

The aim of this study was to evaluate and compare mucin gene expression at epithelial and glandular levels, and to identify potential mucin expression patterns for specific upper airways pathologies.

METHODS

Immunohistochemistry for MUC1, MUC2, and MUC4-MUC8 mucins was performed on healthy nasal mucosa (NM; n=12), bilateral nasal polyps (NP; n=38), NP from CF patients (n=10), and antrochoanal (AC) polyps (n=11). MUC2, MUC4, MUC5AC, and MUC6 mRNA expression were also analysed by in situ hybridization.

RESULTS

MUC1, MUC4, and MUC5AC mucins were highly expressed in the epithelium and their expression pattern was similar in all NP types, MUC1 and MUC4 being increased and MUC5AC decreased compared with NM. MUC8 was highly detected at both epithelial and glandular levels with marked variability between groups. MUC5B was mainly detected in glands and the expression in all polyp types was higher than in NM. Moreover, MUC5B expression was higher in NP epithelia from CF patients than in bilateral NP and healthy NM. Although MUC2 expression was low, especially in AC polyps, it was detected in most samples. In NM, MUC6 and MUC7 were scarcely detected and MUC7 expression was restricted to glands.

CONCLUSIONS

These results suggest that NP have a different pattern of mucin expression than healthy NM and that CF polyps (increased MUC5B) and AC polyps (decreased MUC2) have a different mucin expression pattern than bilateral NP.

MUC1 oncoprotein blocks nuclear targeting of c-Abl in the apoptotic response to DNA damage

The nonreceptor c-Abl tyrosine kinase binds to cytosolic 14-3-3 proteins and is targeted to the nucleus in the apoptotic response to DNA damage. The MUC1 oncoprotein is overexpressed by most human carcinomas and blocks the induction of apoptosis by genotoxic agents. Using human carcinoma cells with gain and loss of MUC1 function, we show that nuclear targeting of c-Abl by DNA damage is abrogated by a MUC1-dependent mechanism. The results demonstrate that c-Abl phosphorylates MUC1 on Tyr-60 and forms a complex with MUC1 by binding of the c-Abl SH2 domain to the pTyr-60 site. Binding of MUC1 to c-Abl attenuates phosphorylation of c-Abl on Thr-735 and the interaction between c-Abl and cytosolic 14-3-3. We also show that expression of MUC1 with a mutation at Tyr-60 (i) disrupts the interaction between MUC1 and c-Abl, (ii) relieves the MUC1-induced block of c-Abl phosphorylation on Thr-735 and binding to 14-3-3, and (iii) attenuates the MUC1 antiapoptotic function. These findings indicate that MUC1 sequesters c-Abl in the cytoplasm and thereby inhibits apoptosis in the response to genotoxic anticancer agents.

A New Competitive Enzyme Linked Immunosorbent Assay (MRP83‐CA15‐3) for MUC1 Measurement in Breast Cancer

A new competitive enzyme linked immunosorbent assay was developed in this study. Monoclonal antibody (PR81) against the tandem repeat of the core protein was prepared, characterized, purified, and conjugated to HRP. This antibody exhibited no cross reactions with proteins such as bovine serum albumin, keyhole limpet homocyanin, human serum albumin, casein, human milk fat globin (HMFG), and peptone. The native cancerous MUC1 protein was purified from ascites fluid of a patient suffering from small cell lung carcinoma by immunoaffinity chromatography and used as a standard preparation in the assay buffer. The standard curve was constructed following a competitive procedure in the range of 0-200 U/mL. The level of MUC1 in normal and cancerous samples was compared following this procedure and using available CA15-3 EIA (Can Ag), as well as LIAISON CA15-3 commercial kits. The correlation coefficient between the procedure reported in this work (MRP83-CA15-3) and CA15-3 EIA (Can Ag) was 0.68 and was 0.95 with the LIAISON CA15-3 kit. We concluded that the present assay can detect MUC1 in breast cancer patients with great sensitivity and accuracy.

Sodium iodide symporter-mediated radioiodide imaging and therapy of ovarian tumor xenografts in mice

Ovarian cancer represents the fifth leading cause of cancer death among women in the United States, with >16 000 deaths expected this year. This study was carried out to investigate the potential of sodium iodide symporter (NIS)-mediated radioiodide therapy as a novel approach for ovarian cancer treatment. Radioiodide is routinely and effectively used for the treatment of benign and malignant thyroid disease as a result of native thyroidal expression of NIS, which mediates iodide uptake. In vitro gene transfer studies in ovarian cancer cells revealed a 12- and five-fold increase in iodide uptake when transduced with Ad/CMV/NIS or Ad/MUC1/NIS, respectively. Western blot/immunohistochemistry confirmed NIS protein expression. In vivo ovarian tumor xenografts were infected with the adenoviral constructs. (123)I imaging revealed a clear image of the CMV/NIS-transduced tumor, with a less intense image apparent following infection with MUC1/NIS. Therapeutic doses of (131)I following CMV/NIS infection caused a mean 53% reduction in tumor volume (P<0.0001). MUC1/NIS-transduced tumors did not regress, although at 8 weeks following therapy, tumor volume was significantly less that of control animals (166 versus 332%, respectively, P<0.05). This study represents a promising first step investigating the potential for NIS-mediated radioiodide imaging and therapy of ovarian tumors.

Cutting edge: enhanced pulmonary clearance of Pseudomonas aeruginosa by Muc1 knockout mice

MUC1 (MUC1 in human and Muc1 in nonhumans) is a membrane-tethered mucin that interacts with Pseudomonas aeruginosa (PA) through flagellin. In this study, we compared PA pulmonary clearance and proinflammatory responses by Muc1(-/-) mice with Muc1(+/+) littermates following intranasal instillation of PA or flagellin. Compared with Muc1(+/+) mice, Muc1(-/-) mice showed increased PA clearance, greater airway recruitment of neutrophils, higher levels of TNF-alpha and KC in bronchoalveolar lavage fluid, higher levels of TNF-alpha in media of flagellin-stimulated alveolar macrophages, and higher levels of KC in media of tracheal epithelial cells. Knockdown of MUC1 enhanced flagellin-induced IL-8 production by primary human bronchial epithelial cells. Expression of MUC1 in HEK293T cells attenuated TLR5-dependent IL-8 release in response to flagellin, which was completely ablated when its cytoplasmic tail was deleted. We conclude that MUC1/Muc1 suppresses pulmonary innate immunity and speculate its anti-inflammatory activity may play an important modulatory role during microbial infection.

MUC1 splice variants in human ocular surface tissues: possible differences between dry eye patients and normal controls

Mucins are highly glycosylated proteins that are vital to the maintenance of healthy epithelial surfaces including the ocular surface. Mucins act as lubricants, protectants, and mediators of signal transduction. The majority of the O-glycosylation sites on the transmembrane mucin MUC1 are found in a highly polymorphic core region containing a variable number of tandem repeats (VNTR). MUC1 alleles can be divided into size classes that contain small (30-45) or large (60-90) numbers of repeats. Although at least 12 splice variants of MUC1 have been found in other tissues, no splice variants have been reported in human ocular surface tissues. We have used RT-PCR to identify MUC1 splice variants that were then confirmed by sequencing. We here report the presence in some samples of human cornea, conjunctiva, and lacrimal gland of MUC1/B which features canonical splicing between exons 1 and 2 and MUC1/A, a transcript that retains 27bp from the 3' end of intron 1 and is predicted to add 9 amino acids to the MUC1 sequence upstream of the tandem repeat region. Cornea and conjunctiva both contain the MUC1/SEC splice variant that lacks the transmembrane domain and, therefore, results in a soluble, secreted form of MUC1. Cornea and conjunctiva also contain MUC1/Y and MUC1/Z(X) variants that lack the tandem repeat region. Cornea, conjunctiva, and lacrimal gland also contain a previously undescribed MUC1 variant transcript, termed MUC1/YI, that retains 99bp from the 5' end and 27bp from the 3' end of the first intron, resulting in a frame shift and premature stop codon. This transcript is predicted to produce a novel 27 amino acid peptide after signal peptidase cleavage. Analysis of brush cytology samples revealed that the percentage of dry eye patients expressing the MUC1/A variant in the conjunctival epithelium is lower than in normal control donors. Western blotting confirmed that MUC1/A is associated with alleles containing the large size class of tandem repeats. Therefore, we propose that one factor in susceptibility to dry eye disease may be the lengths of the MUC1 VNTR in conjunctival epithelium based on the rationale that longer VNTR provide better lubrication and greater protection of the ocular surface against inflammation.

N-Glycosylation of the MUC1 mucin in epithelial cells and secretions

The MUC1 mucin is an important tumor-associated antigen that shows extensive glycosylation in vivo. The O-glycosylation of this molecule, which has been well characterized in many cell types and tissues, is important in conferring the unusual biochemical and biophysical properties on a mucin. N-Glycosylation is crucial to the folding, sorting, membrane trafficking, and secretion of many proteins. Here, we evaluated the N-glycosylation of MUC1 derived from two sources: endogenous MUC1 isolated from human milk and a recombinant epitope-tagged MUC1F overexpressed in Caco2 colon carcinoma cells. N-Glycans on purified MUC1F/MUC1 were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), gas chromatography-mass spectrometry (GC-MS), and CAD-ESI-MS/MS. The spectra indicate that MUC1F N-glycans have compositions consistent with high-mannose structures (Hex(5-9)HexNAc(2)) and complex/hybrid-type glycans (NeuAc(0-3)Fuc(0-3)Hex(3-8)HexNAc(3-7)). Many of the N-glycan structures are identical on MUC1F and native MUC1; however, a marked difference is seen between the N-glycans on membrane-bound and secreted forms of the native molecule.

Recycling of MUC1 is dependent on its palmitoylation

MUC1 is a mucin-like transmembrane protein expressed on the apical surface of epithelia, where it protects the cell surface. The cytoplasmic domain has numerous sites for phosphorylation and docking of proteins involved in signal transduction. In a previous study, we showed that the cytoplasmic YXXphi motif Y20HPM and the tyrosine-phosphorylated Y60TNP motif are required for MUC1 clathrin-mediated endocytosis through binding AP-2 and Grb2, respectively (Kinlough, C. L., Poland, P. A., Bruns, J. B., Harkleroad, K. L., and Hughey, R. P. (2004) J. Biol. Chem. 279, 53071-53077). Palmitoylation of transmembrane proteins can affect their membrane trafficking, and the MUC1 sequence CQC3RRK at the boundary of the transmembrane and cytoplasmic domains mimics reported site(s) of S-palmitoylation. [3H]Palmitate labeling of Chinese hamster ovary cells expressing MUC1 with mutations in CQC3RRK revealed that MUC1 is dually palmitoylated at the CQC motif independent of RRK. Lack of palmitoylation did not affect the cold detergent solubility profile of a chimera (Tac ectodomain and MUC1 transmembrane and cytoplasmic domains), the rate of chimera delivery to the cell surface, or its half-life. Calculation of rate constants for membrane trafficking of wild-type and mutant Tac-MUC1 indicated that the lack of palmitoylation blocked recycling, but not endocytosis, and caused the chimera to accumulate in a EGFP-Rab11-positive endosomal compartment. Mutations CQC/AQA and Y20N inhibited Tac-MUC1 co-immunoprecipitation with AP-1, although mutant Y20N had reduced rates of both endocytosis and recycling, but a normal subcellular distribution. The double mutant chimera AQA+Y20N had reduced endocytosis and recycling rates and accumulated in EGFP-Rab11-positive endosomes, indicating that palmitoylation is the dominant feature modulating MUC1 recycling from endosomes back to the plasma membrane.

O-glycosylated versus non-glycosylated MUC1-derived peptides as potential targets for cytotoxic immunotherapy of carcinoma

Due to the fact that many cellular proteins are extensively glycosylated, processing and presentation mechanisms are expected to produce a pool of major histocompatibility complex (MHC) class I-bound protein-derived peptides, part of which retain sugar moieties. The immunogenic properties of the presented glycosylated peptides in comparison to their non-glycosylated counterparts have not been determined clearly. We assessed the cellular immunogenicity of MUC1 (mucin)-derived peptides O-glycosylated with a Tn epitope (GalNAc) using HLA-A*0201 single chain (HHD)-transfected cell lines and transgenic mice. For part of the compounds Tn moiety did not interfere with the HLA-A*0201 binding. Moreover, part of the glycopeptides elicited effective cytotoxic responses, indicating recognition of the glycopeptide-HLA-A*0201 complex by the T cell receptor (TCR) and subsequent cytotoxic T lymphocyte (CTL) activation. The CTLs exhibited a substantial degree of cross-reactivity against target cells loaded with glycosylated and non-glycosylated forms of the same peptide. The studied (glyco)peptides showed cellular immunogenicity in both MUC1-HHD and HHD mice and induced effective lysis of (glyco)peptide-loaded target cells in CTL assays. However, the elicited CTLs did not induce selective lysis of human MUC1-expressing murine cell lines. Moreover, immunization with (glyco)peptide-loaded dendritic cells (DCs) did not induce significant immunotherapeutic effects. We conclude that Tn glycosylated MUC1-derived peptides can be presented by MHC class I molecules, and may be recognized by specific TCR molecules resulting in cytotoxic immune responses. However, the studied glycopeptides did not offer significant benefit as targets for cytotoxic immune response due apparently to (a) cross-reactivity of the elicited CTLs against the glycosylated and non-glycosylated forms of the same peptide and (b) low abundance of glycopeptides on tumour target cells.

Molecular alterations of monophasic synovial sarcoma: loss of chromosome 3p does not alter RASSF1 and MLH1 transcriptional activity

Differential diagnosis of monophasic synovial sarcoma requires the detection of specific biological markers. In this study we evaluated the presence of molecular alterations in 15 monophasic synovial sarcomas. Multiple changes affecting chromosome arms were detected by CGH-array in all microdissected cases available, and an association between gain or loss of specific regions harbouring cancer progression-associated genes and aneuploid status was found. The most frequent alteration was loss of 3p including 3p21.3-p23 region that, however, did not involve the promoter regions of the corresponding genes, RASSF1 and MLH1. Using Real-Time PCR, mRNA levels of both resulted moderately high compared to normal tissue; however, the weak to absent protein expression suggests RASSF1 and MLH1 post-transcription deregulation. Moreover, immunohistochemical analysis revealed that both mesenchymal and epithelial antigens were present in diploid tumours. These findings confirm the genetic complexity of monophasic synovial sarcoma and underline the need to integrate different analyses for a better knowledge of this tumour, essential to investigate new diagnostic and prognostic markers.

Comparative FISH mapping of mucin 1, transmembrane (MUC1) among cattle, river buffalo, sheep and goat chromosomes: comparison between bovine chromosome 3 and human chromosome 1

Four bovine BAC clones (0494F01, 0069D07, 0060B06, and 0306A12) containing MUC1, as confirmed by mapping MUC1 on a RH3000 radiation hybrid panel, were hybridised on R-banded chromosomes of cattle (BTA), river buffalo (BBU), sheep (OAR) and goat (CHI). MUC1 was FISH-mapped on BTA3q13, BBU6q13, OAR1p13 and CHI3q13 and both chromosomes and chromosome bands were homoeologous confirming the high degree of chromosome homoeologies among bovids and adding more information on the pericentromeric regions of these species' chromosomes. Indeed, MUC1 was more precisely assigned to BTA3 and assigned for the first time to BBU6, OAR1p and CHI3. Moreover, detailed and improved cytogenetic maps of BTA3, CHI3, OAR1p and BBU6 are shown and compared with HSA1.

MUC gene abnormalities in sporadic and hereditary mucinous colon cancers with microsatellite instability

Aim of this study was verifying whether mucin producing colon cancers (CRCs) could develop through a molecular pathway involving microsatellite instability (MSI) and MUC gene alterations. Out of 49 CRCs expressing variable amounts of mucin, 22 (44.9%) were MSI-H and 5 (10.2%) were MSI-L. MUC genes were analyzed by Southern blotting and extra bands were evident in the Variable Number Tandem Repetition (VNTR) regions of MUC2 (5 cases) and MUC5AC (2 cases), but not MUC1 and MUC4 genes. Since the somatic VNTR abnormalities were detected in 6 MSI-H and in 1 MSI-L tumors, they seem to be peculiar of mismatch repair defective CRCs. Our finding suggests that alteration and/or loss of structurally normal MUC genes may be an important step in the neoplastic molecular pathway of a subset of CRCs and that mutations involving VNTR repetitive sequences may exist in MSI tumors as a direct and/or indirect consequence of an inefficient MMR system.

MUC1 oncoprotein blocks glycogen synthase kinase 3beta-mediated phosphorylation and degradation of beta-catenin

Dysregulation of beta-catenin is of importance to the development of diverse human malignancies. The MUC1 oncoprotein is aberrantly overexpressed by most human carcinomas and associates with beta-catenin. However, the functional significance of the MUC1-beta-catenin interaction is not known. Here, we show that MUC1 increases beta-catenin levels in the cytoplasm and nucleus of carcinoma cells. Previous studies have shown that glycogen synthase kinase 3beta (GSK3beta) phosphorylates beta-catenin and thereby targets it for proteosomal degradation. Consistent with the up-regulation of beta-catenin levels, our results show that MUC1 blocks GSK3beta-mediated phosphorylation and degradation of beta-catenin. To further define the interaction between MUC1 and beta-catenin, we identified a serine-rich motif (SRM) in the MUC1 cytoplasmic domain that binds directly to beta-catenin Armadillo repeats. Mutation of the SRM attenuated binding of MUC1 to beta-catenin and MUC1-mediated inhibition of beta-catenin degradation. Importantly, disruption of the MUC1-beta-catenin interaction with the SRM mutant also attenuated MUC1-induced anchorage-dependent and -independent growth and delayed MUC1-mediated tumorigenicity. These findings indicate that MUC1 promotes transformation, at least in part, by blocking GSK3beta-mediated phosphorylation and thereby degradation of beta-catenin.

Quantitative analysis of MUC1 and MUC5AC mRNA in pancreatic juice for preoperative diagnosis of pancreatic cancer

Pancreatic juice is a promising type of diagnostic sample for pancreatic cancer, and members of the mucin (MUC) family are diagnostic candidates. To evaluate the utility of MUC family members as diagnostic markers, we measured MUC mRNA expression in pancreatic tissues and pancreatic juice obtained from patients with different pancreatic diseases as well as in pancreatic cancer cell lines by real-time PCR. Furthermore, to support the possibility of early diagnosis by quantification of MUC1 and MUC5AC, immunohistochemistry and microdissection-based quantitative analysis of mRNA were carried out. There was no significant correlation between MUC1 and MUC5AC expression in cell lines. When beta-actin was used as a reference gene, median MUC1 and MUC5AC mRNA expression levels were remarkably greater in tumoral tissues than in non-tumoral tissues, but median MUC4 and MUC6 mRNA expression levels were not. Receiver operating characteristic curve analysis showed that quantitative analysis of MUC1 and MUC5AC mRNA in pancreatic juice is better diagnostic modality than that of MUC4 and MUC6 mRNA. Immunohistochemistry showed that MUC1 and MUC5AC were highly expressed in invasive ductal carcinomas (IDC) and moderately expressed in high-grade pancreatic intraepithelial neoplasia (PanIN); no staining was observed in normal ducts. Analysis of cells isolated by microdissection showed stepwise upregulation of MUC1 and MUC5AC in the development of high-grade PanIN to IDC. Our results suggest that MUC1 and MUC5AC are upregulated stepwise in pancreatic carcinogenesis and that quantitative assessment of MUC1 and MUC5AC mRNA in pancreatic juice has high potential for preoperative diagnosis of pancreatic cancer.

Autoproteolysis coupled to protein folding in the SEA domain of the membrane-bound MUC1 mucin

The single cell layer of the lungs and the gastrointestinal tract is protected by the mucus formed by large glycoproteins called mucins. Transmembrane mucins typically contain 110-residue SEA domains located next to the membrane. These domains undergo post-translational cleavage between glycine and serine in a characteristic GSVVV sequence, but the two peptides remain tightly associated. We show that the SEA domain of the human MUC1 transmembrane mucin undergoes a novel type of autoproteolysis, which is catalyzed by conformational stress and the conserved serine hydroxyl. We propose that self-cleaving SEA domains have evolved to dissociate as a result of mechanical rather than chemical stress at the apical cell membrane and that this protects epithelial cells from rupture. We further suggest that the cell can register mechanical shear at the mucosal surface if the dissociation is signaled via loss of a SEA-binding protein.

Antitumor effect of double immunization of mice with mucin 1 and its coding DNA

OBJECTIVE

To evaluate the antitumor effect of mouse immunization with human mucin 1 gene (muc 1) DNA plasmids combined with simultaneous injections of human mucin 1 (MUC1) protein.

MATERIALS AND METHODS

MUC1 DNA was cloned in pBK-CMV to prepare DNA plasmids and in pET22b(+) to produce proteins. Three strains of mice, immunized with DNA or DNA plus MUC1, were inoculated with tumor cells obtained from spontaneous tumors. IgG(2a) production, MUC1-specific IFN-delta-producing CD8+ T cells, tumor growth and mouse survival were monitored.

RESULTS

Only immunization with DNA plus proteins induced IgG(2a) and intracellular IFN-delta production by CD8+ T cells in the strains tested. DNA plus protein immunization induced a better mouse survival in comparison with the DNA groups. However, all immunized mice invariably developed tumors.

CONCLUSION

Immunization with DNA plus proteins induced a better protection from tumor growth than immunization with naked DNA. However, the efficacy of immunization with MUC1-based antigens remains low.

Muc1 affects c-Src signaling in PyV MT-induced mammary tumorigenesis

MUC1 is an integral membrane mucin glycoprotein that is normally expressed on the apical surface of most simple, secretory epithelia and hematopoietic cells. Overexpression of aberrantly glycosylated MUC1 is a hallmark of many carcinomas including 90% of breast carcinomas. MUC1 has been shown to bind to c-Src tyrosine kinase in vitro, whereby c-Src phosphorylates the MUC1 cytoplasmic domain at a YEKV motif. c-Src is an extensively studied nonreceptor tyrosine kinase implicated in mammary tumorigenesis. Previously, mouse mammary tumor virus-driven polyoma middle T-antigen (MMTV-PyV MT) transgenic mice crossed onto a Muc1 null background exhibited a significant delay in tumor progression. c-Src has been shown to interact with PyV MT, and to play an integral and indispensable role in MMTV-PyV MT-induced mammary tumorigenesis. Here, we determine the effect of Muc1 expression on c-Src activation and signaling. Examination of MMTV-PyV MT glands on a wild-type or Muc1 null background demonstrates that Muc1 expression promotes c-Src signaling by influencing its association with known substrates such as the p85 subunit of phosphatidylinositol 3-kinase and beta-catenin. These findings may provide a mechanism for the delay in tumor progression that is observed in the absence of Muc1.

The zinc finger of the CSN-associated deubiquitinating enzyme USP15 is essential to rescue the E3 ligase Rbx1

The COP9 signalosome (CSN) is a conserved protein complex found in all eukaryotic cells and involved in the regulation of the ubiquitin (Ub)/26S proteasome system. It binds numerous proteins, including the Ub E3 ligases and the deubiquitinating enzyme Ubp12p, the S. pombe ortholog of human USP15. We found that USP15 copurified with the human CSN complex. Isolated CSN complex exhibited protease activity that deubiquitinated poly-Ub substrates and was completely inhibited by o-phenanthroline (OPT), a metal-chelating agent. Surprisingly, the recombinant USP15 was also not able to cleave isopeptide bonds of poly-Ub chains in presence of OPT. Detailed analysis of USP sequences led to the discovery of a novel zinc (Zn) finger in USP15 and related USPs. Mutation of a single conserved cysteine residue in the predicted Zn binding motif resulted in the loss of USP15 capability to degrade poly-Ub substrates, indicating that the Zn finger is essential for the cleavage of poly-Ub chains. Moreover, pulldown experiments demonstrated diminished binding of tetra-Ub to mutated USP15. Cotransfection of USP15 and the Ub ligase Rbx1 revealed that the wild-type deubiquitinating enzyme, but not the USP15 mutant with a defective Zn finger, stabilized Rbx1 toward the Ub system, most likely by reversing poly/autoubiquitination. In summary, a functional Zn finger of USP15 is needed to maintain a conformation essential for disassembling poly-Ub chains, a prerequisite for rescuing the E3 ligase Rbx1.

Tumor-associated carbohydrate antigens: a possible avenue for cancer prevention

Here we examine the use of glycopeptides containing tumour-associated carbohydrate antigens (TACA) as potential preventive vaccines for carcinomas. Our recent results suggest that CD8+ T cells (CTL) are capable of recognizing TACA in a conventional class I MHC-restricted fashion. The ThomsenFriedenreich antigen (TF), a disaccharide, and Tn, its immediate precursor, are TACA largely expressed in carcinomas. TF and Tn can be successfully used as Th-independent vaccines when conjugated to designer peptides with optimal binding affinity for class I MHC molecules. TF- and Tn-specific CTL generated using this strategy are capable of recognizing TACA-expressing tumours in vitro, suggesting that glycopeptides are as effectively presented by class I MHC molecules as non-glycosylated peptides. Because the exact sequences of endogenously synthesized glycopeptides are unknown, the TACA-specific T cell repertoire elicited by carbohydrate-based vaccines is assumed to be degenerate. Here we report that mice genetically manipulated to develop TACA-expressing mammary tumours are not tolerant to glycopeptide vaccination. Moreover, we tested the immunogenicity of designer glycopeptides capable of binding multiple HLA alleles as a novel approach for the development of vaccines potentially useful for vaccination of a large fraction of the general population. Our results have suggested that CTL derived from normal donors respond with high efficiency to glycopeptides in vitro, opening a new avenue for the design of prospective vaccines for cancer prevention.

MUC1 and MUC5AC mucin expression in liver fluke-associated intrahepatic cholangiocarcinoma

AIM: To investigate the expressions of MUC1 and MUC5AC in intrahepatic cholangiocarcinoma (ICC). Association of expressions of mucins MUC1 and MUC5AC with clinical findings, metastasis, and survival of the liver fluke-associated ICC patients was determined.

METHODS: The expressions of MUC1 and MUC5AC mucins were examined by immunohistochemical staining in 87 cases of histologically-proven ICC. The expressions of mucins in relationship between clinicopathological significance and prognosis of the patients were evaluated.

RESULTS: Fifty-two patients (60%) exhibited both MUC1 and MUC5AC expressions, whereas 31% expressed either MUC1 or MUC5AC, and 9% expressed neither. High MUC1 immunoreactivity displayed a significant correlation with tumor progression as reflected by vascular invasion (P<0.001), whereas high expression of MUC5AC significantly correlated with neural invasion (P = 0.022) and advanced ICC stage (P = 0.008). Patients with high expression of MUC1 had a significantly shorter survival (P = 0.0002). According to multivariate analyses, MUC1 reactivity (P = 0.026), histological grading and stage of tumor represented the least probability of survival.

CONCLUSION: MUC1 is overexpressed in liver fluke-associated cholangiocarcinoma and relates to vascular invasion and poor prognosis, whereas MUC5AC mucin is neoexpressed and relates to neural invasion and advanced ICC stage. High MUC1 expression in tumor may be useful for predicting the poor outcome of ICC patients.

Transcriptional tumor-selective promoter targeting of E. coli purine nucleoside phosphorylase for pancreatic cancer suicide gene therapy

BACKGROUND

Pancreatic cancer remains a rapidly fatal disease. Suicide gene therapy has been shown to be an effective tool for pancreatic tumor cell destruction, but a cell-specific gene delivery is required to limit host toxicity. The objective of this study was both to design recombinant vectors in which the suicide gene E. coli purine nucleoside phosphorylase (ePNP) is under the control of either CEA or MUC1 promoter sequences and to investigate on experimental pancreatic carcinomas the selective killing effects of the conditional ePNP/prodrug (MePdR) system.

METHODS

Transcriptional activities of CEA and MUC1 promoter sequences were analyzed using luciferase reporter gene constructions. Thereafter, recombinant vectors expressing ePNP under control of the most promising pCEA and pMUC1 sequences were designed and used to establish stable tumor cell transfectants from two human pancreatic cell lines, respectively tumor-marker positive (BxPc3) or negative (Panc-1), then applied for in vitro and in vivo experiments.

RESULTS

Transient experiments indicated that CEA and MUC1 promoter sequences confer specificity while preserving high transcriptional activities. The MePdR treatment induced a high in vitro cytotoxicity on the sole CEA- and MUC1-producing cell lines (i.e. BxPc3-CEA and -MUC1/ePNP). In the same way, prodrug treatment induced a significant tumor regression on the sole tumor-marker-positive BxPc3 xenografts, whilst the Panc1-CEA and -MUC1/ePNP tumors were not affected.

CONCLUSIONS

These data confirm and extend the antitumor efficacy of the ePNP/MePdR killing system and demonstrate the feasibility of the transcriptional targeting strategy under tumor marker promoter control and thereby a preferential killing of CEA- and MUC1-producing pancreatic tumor cells. Thus, efficient in vivo gene delivery and transcriptional targeting constitute the major future clinical challenge for a selective pancreatic cancer suicide gene strategy.

MZF-1 and DbpA interact with DNase I hypersensitive sites that correlate with expression of the human MUC1 mucin gene

The MUC1 mucin is a large membrane-tethered glycoprotein that shows differential expression in many adenocarcinomas, where it contributes to their invasive and metastatic properties. We previously identified DNase I hypersensitive sites at -750 and -250 bp in the human MUC1 gene promoter and showed concordance between the -250 site and MUC1 mRNA levels in vivo. Transient expression assays using promoter constructs, in which the core DHS was deleted, to drive reporter gene expression revealed in vivo evidence for their activity. DNase I footprinting using nuclear extracts from HPAF human pancreatic carcinoma cells and MCF7 breast carcinoma cells identified three protein-binding elements in these regions (-250FP1, FP2 and -750FP). Electrophoretic mobility shift assays detected several complexes between HPAF nuclear proteins and labeled FP DNA probes. Southwestern blots and UV cross-linking experiments identified myeloid zinc finger-1 (MZF-1) as a candidate transcription factor among proteins binding to the -250FP1 and FP2 sequences. Another candidate that was identified by screening an HPAF cDNA expression library with the -250FP1 probe is DNA binding protein A (DbpA). Exogenous DbpA expression in COS-7 cells was accompanied by upregulation of MUC1 promoter activity via the -250 DHS, suggesting that DbpA binding to the -250 DHS can influence human MUC1 gene expression.

Sequence-variant repeats of MUC1 show higher conformational flexibility, are less densely O-glycosylated and induce differential B lymphocyte responses

The human epithelial cancer mucin MUC1 is able to break tolerance and to induce humoral immune responses in healthy subjects and in cancer patients. We recently showed that clusters of sequence-variant repeats are interspersed in the repeat domain of MUC1 at high frequency, which should contribute to the structural and immunological features of the mucin. Here we elucidated the potential effects exerted by sequence-variant repeats on their O-glycosylation. Evidence from in vitro glycosylation with polypeptide N-acetylgalactosaminyltransferases GalNAc-T1 and GalNAc-T2 in concert with mass spectrometric analyses of in vivo glycosylated MUC1 probes from transiently transfected HEK293 cells indicated reduced glycosylation densities of repeats with three concerted replacements: AHGVTSAPESRPAPGSTAPA. The Pro to Ala replacement in STAPA exerts not only proximal effects on the ppGalNAc-T2 preferred site at -3 and -4, but also more distant effects on the ppGalNAc-T1 preferred site at -15 (TSAPESRPAPGSTAPA). We also examined the conformational changes of MUC1 glycopeptides induced by the concerted DT to ES replacements and revealed a higher conformational flexibility of ES/P peptides compared to DT/P peptides. Differences in conformational flexibilities and in O-glycosylation densities could underlie the observed differential humoral responses in humans. We were able to show that the natural immunoglobulin G (IgG) responses to the repeat domain of MUC1 in sera from nonmalignant control subjects are preferentially directed to variant repeat clusters. In contrast, the IgG response in patients with adenocarcinoma shifted to higher frequencies of preferential DTR peptide binding.

In vivo radioiodide imaging and treatment of breast cancer xenografts after MUC1-driven expression of the sodium iodide symporter

PURPOSE

Expression of the sodium iodide symporter (NIS) in the thyroid gland provides for effective imaging and treatment of thyroid cancer using radiolabeled iodide. Transfer of NIS into other tumors would expand the utility of this treatment to tumors of nonthyroid origin. MUC1 is a transmembrane glycoprotein that is overexpressed in many tumor types, including breast, pancreatic, and ovarian. The aim of this study was to create a construct containing NIS under the control of the MUC1 promoter to target expression specifically to MUC1-positive breast cancer cells.

EXPERIMENTAL DESIGN

A replication-deficient adenoviral construct was created containing the MUC1 promoter followed by the human NIS gene. Iodide uptake assays, Western blot, and immunohistochemistry were used to confirm NIS expression and function. Breast cancer xenografts in mice were infected with Ad5/MUC1/NIS and then imaged and treated using radioiodide.

RESULTS

A 58-fold increase in iodide uptake was observed in infected MUC1-positive T47D cells with no significant increase observed in MUC1-negative MDA-MB-231 cells or in cells infected with the control virus. The in vivo study yielded clear images of Ad/MUC1/NIS-infected tumor xenografts using (123)I. Administration of a therapeutic dose of (131)I resulted in an 83% reduction in tumor volume, whereas control tumors continued to increase in size (P < 0.01).

CONCLUSIONS

These results show that the MUC1 promoter is capable of directing efficient and selective expression of the NIS gene in MUC1-positive breast tumor cells. This could potentially have applications for both imaging and therapy in a range of MUC1-positive tumor types.

Analyses of recombinant vaccinia and fowlpox vaccine vectors expressing transgenes for two human tumor antigens and three human costimulatory molecules

PURPOSE

The poor immunogenicity of tumor antigens and the antigenic heterogeneity of tumors call for vaccine strategies to enhance T-cell responses to multiple antigens. Two antigens expressed noncoordinately on most human carcinomas are carcinoembryonic antigen (CEA) and MUC-1. We report here the construction and characterization of two viral vector vaccines to address these issues.

EXPERIMENTAL DESIGN

The two viral vectors analyzed are the replication-competent recombinant vaccinia virus (rV-) and the avipox vector, fowlpox (rF-), which is replication incompetent in mammalian cells. Each vector encodes the transgenes for three human costimulatory molecules (B7-1, ICAM-1, and LFA-3, designated TRICOM) and the CEA and MUC-1 transgenes (which also contain agonist epitopes). The vectors are designated rV-CEA/MUC/TRICOM and rF-CEA/MUC/TRICOM.

RESULTS

Each of the vectors is shown to be capable of faithfully expressing all five transgenes in human dendritic cells (DC). DCs infected with either vector are shown to activate both CEA- and MUC-1-specific T-cell lines to the same level as DCs infected with CEA-TRICOM or MUC-1-TRICOM vectors. Thus, no evidence of antigenic competition between CEA and MUC-1 was observed. Human DCs infected with rV-CEA/MUC/TRICOM or rF-CEA/MUC/TRICOM are also shown to be capable of generating both MUC-1- and CEA-specific T-cell lines; these T-cell lines are in turn shown to be capable of lysing targets pulsed with MUC-1 or CEA peptides as well as human tumor cells endogenously expressing MUC-1 and/or CEA.

CONCLUSION

These studies provide the rationale for the clinical evaluation of these multigene vectors in patients with a range of carcinomas expressing MUC-1 and/or CEA.

Polymorphism of the MUC1 mucin gene is associated with susceptibility to lung adenocarcinoma and poor prognosis

MUC1 is a highly glycosylated glycoprotein that is often overexpressed in adenocarcinomas. MUC1 has molecular diversity because of a variable number of tandem repeats (from 25-125 repeats) in the extracellular domain of its core protein. MUC1 plays an important role in facilitating invasion and metastasis of malignant cells, and it also inhibits anti-cancer immune activity against malignant cells. We hypothesize that MUC1 allele length polymorphism (variable number of tandem repeats) is associated with development of lung adenocarcinoma. We evaluated MUC1 gene polymorphism using Southern blot analysis of peripheral blood from patients with non-small cell lung cancer (n=56), patients with benign respiratory disease (n=52), and healthy volunteers (n=52). We found that large MUC1 allele length was significantly associated with lung adenocarcinoma but not with squamous cell carcinoma of the lung. Adenocarcinoma patients with a homozygous large MUC1 genotype had a worse prognosis than patients with a heterozygous (large + small) MUC1 genotype or a homozygous small MUC1 genotype. These results suggest that the large MUC1 allele is associated with susceptibility to lung adenocarcinoma and poor prognosis.

Transmembrane and secreted MUC1 probes show trafficking-dependent changes in O-glycan core profiles

The human mucin MUC1 is expressed both as a transmembrane heterodimeric protein complex that recycles via the trans-Golgi network (TGN) and as a secreted isoform. To determine whether differences in cellular trafficking might influence the O-glycosylation profiles on these isoforms, we developed a model system consisting of membrane-bound and secretory-recombinant glycosylation probes. Secretory MUC1-S contains only a truncated repeat domain, whereas in MUC1-M constructs this domain is attached to the native transmembrane and cytoplasmic domains of MUC1 either directly (M0) or via an intermitting nonfunctional (M1) or functional sperm protein-enterokinase-agrin (SEA) module (M2); the SEA module contains a putative proteolytic cleavage site and is associated with proteins receiving extensive O-glycosylation. We showed that MUC1-M2 simulates endogenous MUC1 by recycling from the cell surface of Chinese hamster ovary (CHO) mutant ldlD14 cells through intracellular compartments where its glycosylation continues. The profiles of O-linked glycans on MUC1-S secreted by epithelial EBNA-293 and MCF-7 breast cancer cells revealed patterns dominated by core 2-based oligosaccharides. In contrast, the respective membrane-shed probes expressed in the same cells showed a complete shift to patterns dominated by sialyl core 1. In conclusion, glycan core profiles reflected the subcellular trafficking pathways of the secretory or membranous probes and the modifying activities of the resident glycosyltransferases.