MUC1-C oncoprotein as a target in breast cancer: activation of signaling pathways and therapeutic approaches

Localized Chemical Remodeling for Live Cell Imaging of Protein-Specific Glycoform

Live cell imaging of protein-specific glycoforms is important for the elucidation of glycosylation mechanisms and identification of disease states. The currently used metabolic oligosaccharide engineering (MOE) technology permits routinely global chemical remodeling (GCM) for carbohydrate site of interest, but can exert unnecessary whole-cell scale perturbation and generate unpredictable metabolic efficiency issue. A localized chemical remodeling (LCM) strategy for efficient and reliable access to protein-specific glycoform information is reported. The proof-of-concept protocol developed for MUC1-specific terminal galactose/N-acetylgalactosamine (Gal/GalNAc) combines affinity binding, off-on switchable catalytic activity, and proximity catalysis to create a reactive handle for bioorthogonal labeling and imaging. Noteworthy assay features associated with LCM as compared with MOE include minimum target cell perturbation, short reaction timeframe, effectiveness as a molecular ruler, and quantitative analysis capability.

Targeting MUC1 and JNK by RNA interference and inhibitor inhibit the development of hepatocellular carcinoma

Mucin 1 (MUC1), as an oncogene, is overexpressed in hepatocellular carcinoma (HCC) cells and promotes the progression and tumorigenesis of HCC through JNK/TGF-β signaling pathway. In the present study, RNA interference (RNAi) and JNK inhibitor SP600125, which target MUC1 and/or JNK, were used to treat HCC cells in vitro, and the results showed that both silencing the expression of MUC1 and blocking the activity of JNK inhibited the proliferation of HCC cells. In addition, MUC1-stable-knockdown and SP600125 significantly inhibited the growth of tumors in the subcutaneous transplant tumor models that established in BALB/c nude mice rather than MUC1 or JNK siRNAs transiently transfection. Furthermore, the results from immunohistochemical staining assays showed that the inhibitory effects of MUC1 gene silencing and SP600125 on the proliferation of HCC cells in vivo were through the JNK/TGF-β signaling pathway. These results indicate that MUC1 and JNK are attractive targets for HCC therapy and may provide new therapeutic strategies for the treatment of HCC.

HEG1 is a novel mucin-like membrane protein that serves as a diagnostic and therapeutic target for malignant mesothelioma

The absence of highly specific markers for malignant mesothelioma (MM) has served an obstacle for its diagnosis and development of molecular-targeting therapy against MM. Here, we show that a novel mucin-like membrane protein, sialylated protein HEG homolog 1 (HEG1), is a highly specific marker for MM. A monoclonal antibody against sialylated HEG1, SKM9-2, can detect even sarcomatoid and desmoplastic MM. The specificity and sensitivity of SKM9-2 to MM reached 99% and 92%, respectively; this antibody did not react with normal tissues. This accurate discrimination by SKM9-2 was due to the recognition of a sialylated O-linked glycan with HEG1 peptide. We also found that gene silencing of HEG1 significantly suppressed the survival and proliferation of mesothelioma cells; this result suggests that HEG1 may be a worthwhile target for function-inhibition drugs. Taken together, our results indicate that sialylated HEG1 may be useful as a diagnostic and therapeutic target for MM.

SERS- and luminescence-active Au-Au-UCNP trimers for attomolar detection of two cancer biomarkers

Alpha-fetoprotein (AFP) and mucoprotein1 (mucin-1) are two important disease biomarkers. Self-assembled gold nanoparticles (AuNPs) and upconversion nanoparticle (Au-Au-UCNP) trimers based on aptamers were developed for the ultrasensitive detection of AFP and mucin-1. The Au-Au-UCNP trimers produced ideal optical signals, with prominent Raman enhancement and fluorescence quenching effects. The surface-enhanced Raman scattering (SERS) intensity decreased in the presence of mucin-1 and the luminescence intensity increased in the presence of AFP. A limit of detection (LOD) of 4.1 aM and a wide linear range of 0.01-10 fM for the detection of mucin-1 were obtained with this SERS-encoded sensing system. Using the luminescence-encoded sensing system, a LOD of 0.059 aM and a wide linear range of 1-100 aM for the detection of AFP were obtained. These LODs are the lowest values reported so far. This approach has the advantage of detecting two disease biomarkers simultaneously.

MUC1-C Oncoprotein Integrates a Program of EMT, Epigenetic Reprogramming and Immune Evasion in Human Carcinomas

The MUC1 gene evolved in mammalian species to provide protection of epithelia. The transmembrane MUC1 C-terminal subunit (MUC1-C) signals stress to the interior of the epithelial cell and, when overexpressed as in most carcinomas, functions as an oncoprotein. MUC1-C induces the epithelial-mesenchymal transition (EMT) by activating the inflammatory NF-κB p65 pathway and, in turn, the EMT-transcriptional repressor ZEB1. Emerging evidence has indicated that MUC1-C drives a program integrating the induction of EMT with activation of stem cell traits, epigenetic reprogramming and immune evasion. This mini-review focuses on the potential importance of this MUC1-C program in cancer progression.

MUC1-C integrates PD-L1 induction with repression of immune effectors in non-small-cell lung cancer

Immunotherapeutic approaches, particularly PD-1/PD-L1 blockade, have improved the treatment of non-small cell lung cancer (NSCLC), supporting the premise that evasion of immune destruction is of importance for NSCLC progression. However, the signals responsible for upregulation of PD-L1 in NSCLC cells and whether they are integrated with the regulation of other immune-related genes are not known. Mucin 1 (MUC1) is aberrantly overexpressed in NSCLC, activates the NF-κB p65→ZEB1 pathway and confers a poor prognosis. The present studies demonstrate that MUC1-C activates PD-L1 expression in NSCLC cells. We show that MUC1-C increases NF-κB p65 occupancy on the CD274/PD-L1 promoter and thereby drives CD274 transcription. Moreover, we demonstrate that MUC1-C-induced activation of NF-κB→ZEB1 signaling represses the TLR9, IFNG, MCP-1 and GM-CSF genes, and that this signature is associated with decreases in overall survival. In concert with these results, targeting MUC1-C in NSCLC tumors suppresses PD-L1 and induces these effectors of innate and adaptive immunity. These findings support a previously unrecognized central role for MUC1-C in integrating PD-L1 activation with suppression of immune effectors and poor clinical outcome.

MUC13 overexpression in renal cell carcinoma plays a central role in tumor progression and drug resistance

Metastatic renal cell carcinoma is a largely incurable disease, and existing treatments targeting angiogenesis and tyrosine kinase receptors are only partially effective. Here we reveal that MUC13, a cell surface mucin glycoprotein, is aberrantly expressed by most renal cell carcinomas, with increasing expression positively correlating with tumor grade. Importantly, we demonstrated that high MUC13 expression was a statistically significant independent predictor of poor survival in two independent cohorts, particularly in stage 1 cancers. In cultured renal cell carcinoma cells MUC13 promoted proliferation and induced the cell cycle regulator, cyclin D1, and inhibited apoptosis by inducing the anti-apoptotic proteins, BCL-xL and survivin. Silencing of MUC13 expression inhibited migration and invasion, and sensitized renal cancer cells to killing by the multi-kinase inhibitors used clinically, sorafenib and sunitinib, and reversed acquired resistance to these drugs. Furthermore, we demonstrated that MUC13 promotion of renal cancer cell growth and survival is mediated by activation of nuclear factor κB, a transcription factor known to regulate the expression of genes that play key roles in the development and progression of cancer. These results show that MUC13 has potential as a prognostic marker for aggressive early stage renal cell cancer and is a plausible target to sensitize these tumors to therapy.

Systematic Identification and Assessment of Therapeutic Targets for Breast Cancer Based on Genome-Wide RNA Interference Transcriptomes

With accumulating public omics data, great efforts have been made to characterize the genetic heterogeneity of breast cancer. However, identifying novel targets and selecting the best from the sizeable lists of candidate targets is still a key challenge for targeted therapy, largely owing to the lack of economical, efficient and systematic discovery and assessment to prioritize potential therapeutic targets. Here, we describe an approach that combines the computational evaluation and objective, multifaceted assessment to systematically identify and prioritize targets for biological validation and therapeutic exploration. We first establish the reference gene expression profiles from breast cancer cell line MCF7 upon genome-wide RNA interference (RNAi) of a total of 3689 genes, and the breast cancer query signatures using RNA-seq data generated from tissue samples of clinical breast cancer patients in the Cancer Genome Atlas (TCGA). Based on gene set enrichment analysis, we identified a set of 510 genes that when knocked down could significantly reverse the transcriptome of breast cancer state. We then perform multifaceted assessment to analyze the gene set to prioritize potential targets for gene therapy. We also propose drug repurposing opportunities and identify potentially druggable proteins that have been poorly explored with regard to the discovery of small-molecule modulators. Finally, we obtained a small list of candidate therapeutic targets for four major breast cancer subtypes, i.e., luminal A, luminal B, HER2+ and triple negative breast cancer. This RNAi transcriptome-based approach can be a helpful paradigm for relevant researches to identify and prioritize candidate targets for experimental validation.

Targeting MUC1-C inhibits the AKT-S6K1-elF4A pathway regulating TIGAR translation in colorectal cancer

Background

Colorectal cancer is third most common malignancy and is the second most common cause of cancer-related death. The MUC1 heterodimeric protein is aberrantly overexpressed in colorectal cancer and has been linked to poor outcomes in this disease. Here, we investigate the effects of the MUC1-C subunit inhibitor (GO-203), which disrupts MUC1-C homo-oligomerization, on human colorectal cancer cells.

Methods

TIGAR mRNA level was determined using qRT-PCR. Western blotting was used to measure TIGAR protein level and AKT-mTOR-S6K1 pathways. Reactive oxygen species and apoptosis were measured by flow cytometry. Effect of MUC1-C peptide, GO-203 was studied on colorectal xenograft tumors. Immunohistochemistry was utilized for TIGAR staining.

Results

Treatment of MUC1-overexpressing SKCO-1 and Colo-205 colon cancer cells with GO-203 was associated with downregulation of the TP53-inducible glycolysis and apoptosis regulator (TIGAR) protein. TIGAR promotes the shunting of glycolytic intermediates into the pentose phosphate pathway and thus is of importance for maintaining redox balance. We show that GO-203-induced suppression of TIGAR is mediated by inhibition of AKT and the downstream mTOR pathway. The results also demonstrate that targeting MUC1-C blocks eIF4A cap-dependent translation of TIGAR. In concert with these results, GO-203-induced suppression of TIGAR was associated with decreases in GSH levels. GO-203 treatment also resulted in increases in reactive oxygen species (ROS) and loss of mitochondrial transmembrane potential. Consistent with these results, GO-203 inhibited the growth of colon cancer cells in vitro and as xenografts in nude mice. Inhibition of MUC1-C also downregulated TIGAR expression in xenograft tissues.

Conclusions

These findings indicate that MUC1-C is a potential target for the treatment of colorectal cancer. Colorectal cancer patients who overexpress MUC1-C may be candidates for treatment with the MUC1-C inhibitor alone or in combination therapy with other agents.

Aberrant control of NF-κB in cancer permits transcriptional and phenotypic plasticity, to curtail dependence on host tissue: molecular mode

The role of the transcription factor NF-κB in shaping the cancer microenvironment is becoming increasingly clear. Inflammation alters the activity of enzymes that modulate NF-κB function, and causes extensive changes in genomic chromatin that ultimately drastically alter cell-specific gene expression. NF-κB regulates the expression of cytokines and adhesion factors that control interactions among adjacent cells. As such, NF-κB fine tunes tissue cellular composition, as well as tissues' interactions with the immune system. Therefore, NF-κB changes the cell response to hormones and to contact with neighboring cells. Activating NF-κB confers transcriptional and phenotypic plasticity to a cell and thereby enables profound local changes in tissue function and composition. Research suggests that the regulation of NF-κB target genes is specifically altered in cancer. Such alterations occur not only due to mutations of NF-κB regulatory proteins, but also because of changes in the activity of specific proteostatic modules and metabolic pathways. This article describes the molecular mode of NF-κB regulation with a few characteristic examples of target genes.

DNA methylation by DNMT1 and DNMT3b methyltransferases is driven by the MUC1-C oncoprotein in human carcinoma cells

Aberrant expression of the DNA methyltransferases (DNMTs) and disruption of DNA methylation patterns are associated with carcinogenesis and cancer cell survival. The oncogenic MUC1-C protein is aberrantly overexpressed in diverse carcinomas; however, there is no known link between MUC1-C and DNA methylation. Our results demonstrate that MUC1-C induces the expression of DNMT1 and DNMT3b, but not DNMT3a, in breast and other carcinoma cell types. We show that MUC1-C occupies the DNMT1 and DNMT3b promoters in complexes with NF-κB p65 and drives DNMT1 and DNMT3b transcription. In this way, MUC1-C controls global DNA methylation as determined by analysis of LINE-1 repeat elements. The results further demonstrate that targeting MUC1-C downregulates DNA methylation of the CDH1 tumor suppressor gene in association with induction of E-cadherin expression. These findings provide compelling evidence that MUC1-C is of functional importance to induction of DNMT1 and DNMT3b and, in turn, changes in DNA methylation patterns in cancer cells.

Personalized characterization of diseases using sample-specific networks

A complex disease generally results not from malfunction of individual molecules but from dysfunction of the relevant system or network, which dynamically changes with time and conditions. Thus, estimating a condition-specific network from a single sample is crucial to elucidating the molecular mechanisms of complex diseases at the system level. However, there is currently no effective way to construct such an individual-specific network by expression profiling of a single sample because of the requirement of multiple samples for computing correlations. We developed here with a statistical method, i.e. a sample-specific network (SSN) method, which allows us to construct individual-specific networks based on molecular expressions of a single sample. Using this method, we can characterize various human diseases at a network level. In particular, such SSNs can lead to the identification of individual-specific disease modules as well as driver genes, even without gene sequencing information. Extensive analysis by using the Cancer Genome Atlas data not only demonstrated the effectiveness of the method, but also found new individual-specific driver genes and network patterns for various types of cancer. Biological experiments on drug resistance further validated one important advantage of our method over the traditional methods, i.e. we can even identify such drug resistance genes that actually have no clear differential expression between samples with and without the resistance, due to the additional network information.

MUC1-C activates BMI1 in human cancer cells

BMI1 is a component of the PRC1 complex that is overexpressed in breast and other cancers, and promotes self-renewal of cancer stem-like cells. The oncogenic mucin 1 (MUC1) C-terminal (MUC1-C) subunit is similarly overexpressed in human carcinoma cells and has been linked to their self-renewal. There is no known relationship between MUC1-C and BMI1 in cancer. The present studies demonstrate that MUC1-C drives BMI1 transcription by a MYC-dependent mechanism in breast and other cancer cells. In addition, we show that MUC1-C blocks miR-200c-mediated downregulation of BMI1 expression. The functional significance of this MUC1-C→BMI1 pathway is supported by the demonstration that targeting MUC1-C suppresses BMI1-induced ubiquitylation of H2A and thereby derepresses homeobox HOXC5 and HOXC13 gene expression. Notably, our results further show that MUC1-C binds directly to BMI1 and promotes occupancy of BMI1 on the CDKN2A promoter. In concert with BMI1-induced repression of the p16^INK4a tumor suppressor, we found that targeting MUC1-C is associated with induction of p16^INK4a expression. In support of these results, analysis of three gene expresssion datasets demonstrated highly significant correlations between MUC1-C and BMI1 in breast cancers. These findings uncover a previously unrecognized role for MUC1-C in driving BMI1 expression and in directly interacting with this stem cell factor, linking MUC1-C with function of the PRC1 in epigenetic gene silencing.

Plasma levels and diagnostic utility of VEGF, MMP-2 and TIMP-2 in the diagnostics of breast cancer patients

OBJECTIVE

We investigated plasma levels and diagnostic utility of vascular endothelial growth factor VEGF, matrix metalloproteinase-2 (MMP-2) and tissue inhibitors of metalloproteinase-2 (TIMP-2) in comparison to cancer antigen 15-3 (CA 15-3).

METHODS

Plasma levels of tested parameters were determined using enzyme-linked immunosorbent assay (ELISA) while CA 15-3 with chemiluminescent microparticle immunoassay (CMIA).

RESULTS

The plasma levels of VEGF, TIMP-2 showed significantly higher than CA 15-3 values of the diagnostic sensitivity, the predictive values of positive and negative test results (PPV, NPV) and the area under the receiver-operating characteristics (ROC) curve (AUC) in early stages of breast cancer (BC). The combined use of the tested parameters with CA 15-3 resulted in the increase in sensitivity, NPV and AUC, especially in the combination with VEGF (83%; 72%; 0.888) and TIMP-2 (83%; 72%; 0.894). The highest values were obtained for combination of all three parameters (93%; 85%; 0.923).

CONCLUSIONS

These findings suggest the usefulness of the tested parameters in the diagnosis of BC, especially VEGF and TIMP-2 with CA 15-3 in early stages of BC, which could be a new diagnostic panel.

Restoring anti-oncodriver Th1 responses with dendritic cell vaccines in HER2/neu-positive breast cancer: progress and potential

HER2/neu is expressed in the majority of in situ breast cancers, but maintained in 20-30% of invasive breast cancer (IBC). During breast tumorigenesis, there is a progressive loss of anti-HER2 CD4(pos) Th1 (anti-HER2Th1) from benign to ductal carcinoma in situ, with almost complete loss in IBC. This anti-HER2Th1 response can predict response to neoadjuvant therapy, risk of recurrence and disease-free survival. Vaccines consisting of HER2-pulsed type I polarized dendritic cells (DC1) administered during ductal carcinoma in situ and early IBC can efficiently correct anti-HER2Th1 response and have clinical impact on the disease. In this review, we will discuss the role of anti-HER2Th1 response in the three phases of immunoediting during HER2 breast cancer development and opportunities for reversing these processes using DC1 vaccines alone or in combination with standard therapies. Correcting the anti-HER2Th1 response may represent an opportunity for improving outcomes and providing a path to eliminate escape variants.

MUC1-C Represses the Crumbs Complex Polarity Factor CRB3 and Downregulates the Hippo Pathway

Apical-basal polarity and epithelial integrity are maintained in part by the Crumbs (CRB) complex. The C--terminal subunit of MUC1 (MUC1-C) is a transmembrane protein that is expressed at the apical border of normal epithelial cells and aberrantly at high levels over the entire surface of their transformed counterparts. However, it is not known whether MUC1-C contributes to this loss of polarity that is characteristic of carcinoma cells. Here it is demonstrated that MUC1-C downregulates expression of the Crumbs complex CRB3 protein in triple-negative breast cancer (TNBC) cells. MUC1-C associates with ZEB1 on the CRB3 promoter and represses CRB3 transcription. Notably, CRB3 activates the core kinase cassette of the Hippo pathway, which includes LATS1 and LATS2. In this context, targeting MUC1-C was associated with increased phosphorylation of LATS1, consistent with activation of the Hippo pathway, which is critical for regulating cell contact, tissue repair, proliferation, and apoptosis. Also shown is that MUC1-C--mediated suppression of CRB3 and the Hippo pathway is associated with dephosphorylation and activation of the oncogenic YAP protein. In turn, MUC1-C interacts with YAP, promotes formation of YAP/β-catenin complexes, and induces the WNT target gene MYC. These data support a previously unrecognized pathway in which targeting MUC1-C in TNBC cells (i) induces CRB3 expression, (ii) activates the CRB3-driven Hippo pathway, (iii) inactivates YAP, and thereby (iv) suppresses YAP/β-catenin-mediated induction of MYC expression.

IMPLICATIONS

These findings demonstrate a previously unrecognized role for the MUC1-C oncoprotein in the regulation of polarity and the Hippo pathway in breast cancer. Mol Cancer Res; 14(12); 1266-76. ©2016 AACR.

Interleukin-30 Promotes Breast Cancer Growth and Progression

The inflammatory tissue microenvironment that promotes the development of breast cancer is not fully understood. Here we report a role for elevated IL30 in supporting the breast cancer cell viability and invasive migration. IL30 was absent in normal mammary ducts, ductules, and acini of histologically normal breast and scanty in the few stromal infiltrating leukocytes. In contrast, IL30 was expressed frequently in breast cancer specimens where it was associated with triple-negative and HER2⁺ molecular subtypes. In stromal leukocytes found in primary tumors or tumor-draining lymph nodes, which included mainly CD14⁺ monocytes, CD68⁺ macrophages, and CD33⁺/CD11b⁺ myeloid cells, IL30 levels increased with disease stage and correlated with recurrence. A negative correlation was determined between IL30 expression by nodal stromal leukocytes and overall survival. In vitro studies showed that human recombinant IL30 upregulated expression of a pro-oncogenic program, including especially IL6 in both triple-negative and HER2⁺ breast cancer cells. In triple-negative breast cancer cells, IL30 boosted a broader program of proliferation, invasive migration, and an inflammatory milieu associated with KISS1-dependent metastasis. Silencing of STAT1/STAT3 signaling hindered the regulation of the primary growth and progression factors in breast cancer cells. IL30 administration in vivo fostered the growth of triple-negative breast cancer by promoting proliferation and vascular dissemination of cancer cells and the accumulation of intratumoral CD11b⁺/Gr1⁺ myeloid cell infiltrates. Overall, our results show how IL30 regulates breast cancer cell viability, migration, and gene expression to promote breast cancer growth and progression and its impact on patient outcome. Cancer Res; 76(21); 6218-29. ©2016 AACR.

Acquired resistance to HSP90 inhibitor 17-AAG and increased metastatic potential are associated with MUC1 expression in colon carcinoma cells

Heat shock protein 90 (HSP90) is a molecular chaperone required for the stability and function of many proteins. The chaperoning of oncoproteins by HSP90 enhances the survival, growth, and invasive potential of cancer cells. HSP90 inhibitors are promising new anticancer agents, in which the benzoquinone ansamycin 17-allylamino-17-demethoxygeldanamycin (17-AAG) is currently in clinical evaluation. However, the implications of acquired resistance to this class of drug remain largely unexplored. In the present study, we have generated isogenic human colon cancer cell lines that are resistant to 17-AAG by continued culturing in the compound. Cross-resistance was found with another HSP90 inhibitor 17-dimethylaminoethylamino-17-demethoxygeldanamycin. The resistant cells showed obvious morphology changes with a metastatic phenotype and significant increases in migration and adhesion to collagens. Western blotting analysis of epithelial-mesenchymal transition molecular markers found that expression of E-cadherin downregulated, whereas expression of N-cadherin and β-catenin upregulated in the resistant cells. Mucin 1 (MUC1) has been reported to mediate metastasis as well as chemical resistance in many cancers. Here, we found that MUC1 expression was significantly elevated in the acquired drug resistance cells. 17-AAG treatment could decrease MUC1 more in parental cells than in acquired 17-AAG-resistant cells. Further study found that knockdown of MUC1 expression by small interfering RNA could obviously re-sensitize the resistant cells to 17-AAG treatment, and decrease the cell migration and adhesion. These were coupled with a downregulation in N-cadherin and β-catenin. The results indicate that HSP90 inhibitor therapies in colon carcinomas could generate resistance and increase metastatic potential that might mediated by upregulation of MUC1 expression. Findings from this study further our understanding of the potential clinical effects of HSP90-directed therapies in colon carcinomas.

Functional Consequences of Differential O-glycosylation of MUC1, MUC4, and MUC16 (Downstream Effects on Signaling)

Glycosylation is one of the most abundant post-translational modifications that occur within the cell. Under normal physiological conditions, O-linked glycosylation of extracellular proteins is critical for both structure and function. During the progression of cancer, however, the expression of aberrant and truncated glycans is commonly observed. Mucins are high molecular weight glycoproteins that contain numerous sites of O-glycosylation within their extracellular domains. Transmembrane mucins also play a functional role in monitoring the surrounding microenvironment and transducing these signals into the cell. In cancer, these mucins often take on an oncogenic role and promote a number of pro-tumorigenic effects, including pro-survival, migratory, and invasive behaviors. Within this review, we highlight both the processes involved in the expression of aberrant glycan structures on mucins, as well as the potential downstream impacts on cellular signaling.

Mucin-Type O-Glycosylation in Gastric Carcinogenesis

Mucin-type O-glycosylation plays a crucial role in several physiological and pathological processes of the gastric tissue. Modifications in enzymes responsible for key glycosylation steps and the consequent abnormal biosynthesis and expression of their glycan products constitute well-established molecular hallmarks of disease state. This review addresses the major role played by mucins and associated O-glycan structures in Helicobacter pylori adhesion to the gastric mucosa and the subsequent establishment of a chronic infection, with concomitant drastic alterations of the gastric epithelium glycophenotype. Furthermore, alterations of mucin expression pattern and glycan signatures occurring in preneoplastic lesions and in gastric carcinoma are also described, as well as their impact throughout the gastric carcinogenesis cascade and in cancer progression. Altogether, mucin-type O-glycosylation alterations may represent promising biomarkers with potential screening and prognostic applications, as well as predictors of cancer patients' response to therapy.

MUC13 protects colorectal cancer cells from death by activating the NF-κB pathway and is a potential therapeutic target

MUC13 is a transmembrane mucin glycoprotein that is over produced by many cancers, although its functions are not fully understood. Nuclear factor-κB (NF-κB) is a key transcription factor promoting cancer cell survival, but therapeutically targeting this pathway has proved difficult because NF-κB has pleiotropic functions. Here, we report that MUC13 prevents colorectal cancer cell death by promoting two distinct pathways of NF-kB activation, consequently upregulating BCL-X_L. MUC13 promoted tumor necrosis factor (TNF)-induced NF-κB activation by interacting with TNFR1 and the E3 ligase, cIAP1, to increase ubiquitination of RIPK1. MUC13 also promoted genotoxin-induced NF-κB activation by increasing phosphorylation of ATM and SUMOylation of NF-κB essential modulator. Moreover, elevated expression of cytoplasmic MUC13 and NF-κB correlated with colorectal cancer progression and metastases. Our demonstration that MUC13 enhances NF-κB signaling in response to both TNF and DNA-damaging agents provides a new molecular target for specific inhibition of NF-κB activation. As proof of principle, silencing MUC13 sensitized colorectal cancer cells to killing by cytotoxic drugs and inflammatory signals and abolished chemotherapy-induced enrichment of CD133⁺ CD44⁺ cancer stem cells, slowed xenograft growth in mice, and synergized with 5-fluourouracil to induce tumor regression. Therefore, these data indicate that combining chemotherapy and MUC13 antagonism could improve the treatment of metastatic cancers.

MUC1 in hematological malignancies

Mucin1 (MUC1) is a transmembrane oncogenic protein that plays a central role in malignant transformation and disease evolution, including cell proliferation, survival, self-renewal, and metastatic invasion. MUC1 has been shown to interact with diverse effectors such as β-catenin, receptor tyrosine kinases, and c-Abl, which are of importance in the pathogenesis of various hematological malignancies. In myeloid leukemia, MUC1 has been shown to have an essential role in leukemia stem-cell function, the induction of reactive oxygen species (ROS), and the promotion of terminal myeloid differentiation. As such, MUC1 is an attractive therapeutic target in hematologic malignancies. Targeting MUC1 has been shown to be an effective approach for inducing cell death in tumor in in vivo and in vitro models. Furthermore, MUC1 inhibition is synergistic with other therapeutic agents in the treatment of hematologic disorders. This review will explore the role of MUC1 in hematological malignancies, and strategies for targeting this oncoprotein.

Differential expression of mucins in Middle Eastern patients with colorectal cancer

Mucin overexpression has been implicated in the tumorigenesis and progression of colorectal carcinoma (CRC). However, data obtained on the prognostic importance of mucin expression in CRC is inconsistent. Due to lack of data on mucin expression and the increase in CRC incidence in Saudi Arabia, the aim of the present study was to analyze the mucin expression profile in patients with CRC in this ethnic group. The present study consisted of 22 patients that underwent surgery for CRC. Histopathological and immunohistochemical staining was performed on CRC tumor and adjacent normal tissues. A tissue microarray was prepared from the tumor and normal adjacent samples to investigate the mucin expression profile using immunohistochemistry. Formalin-fixed paraffin-embedded human colorectal cancer tissues were immunostained with mucin 1 (MUC1), mucin 2 (MUC2) and mucin 5AC (MUC5AC) antibodies. Associations between mucin expression and histopathological variables were evaluated. The present study indicated that MUC1 was highly expressed in early (stage I and II; P=0.0016) and late (stage III and IV; P<0.0001) stage CRC tissues compared to normal adjacent tissues. However, MUC2 expression was observed to be downregulated in early and late stage CRC tissues compared to normal and adjacent tissues. Furthermore, serum MUC1 levels were observed to be increased in early and late stage CRC. The present findings indicate that MUC1 expression was significantly higher in early and late stage CRC tissues and MUC2 was downregulated in CRC tissues compared with normal adjacent tissues, and serum MUC1 protein was significantly higher in CRC patients compared to control serum. In conclusion, during colorectal tumorigenesis the pattern of MUC1 and MUC2 expression is altered in Saudi Arabian patients with CRC compared with normal. A higher expression of MUC1 may be used as an independent biomarker in various stages of CRC tumors, which would aid in the early detection of CRC.

MUC1-C Stabilizes MCL-1 in the Oxidative Stress Response of Triple-Negative Breast Cancer Cells to BCL-2 Inhibitors

Aberrant expression of myeloid cell leukemia-1 (MCL-1) is a major cause of drug resistance in triple-negative breast cancer (TNBC) cells. Mucin 1 (MUC1) is a heterodimeric oncoprotein that is aberrantly overexpressed in most TNBC. The present studies show that targeting the oncogenic MUC1 C-terminal subunit (MUC1-C) in TNBC cells with silencing or pharmacologic inhibition with GO-203 is associated with downregulation of MCL-1 levels. Targeting MUC1-C suppresses the MEK → ERK and PI3K → AKT pathways, and in turn destabilizes MCL-1. The small molecules ABT-737 and ABT-263 target BCL-2, BCL-XL and BCL-w, but not MCL-1. We show that treatment with ABT-737 increases reactive oxygen species and thereby MUC1-C expression. In this way, MUC1-C is upregulated in TNBC cells resistant to ABT-737 or ABT-263. We also demonstrate that MUC1-C is necessary for the resistance-associated increases in MCL-1 levels. Significantly, combining GO-203 with ABT-737 is synergistic in inhibiting survival of parental and drug resistant TNBC cells. These findings indicate that targeting MUC1-C is a potential strategy for reversing MCL-1-mediated resistance in TNBC.

Signalling mucin Msb2 Regulates adaptation to thermal stress in Candida albicans

Temperature is a potent inducer of fungal dimorphism. Multiple signalling pathways control the response to growth at high temperature, but the sensors that regulate these pathways are poorly defined. We show here that the signalling mucin Msb2 is a global regulator of temperature stress in the fungal pathogen Candida albicans. Msb2 was required for survival and hyphae formation at 42°C. The cytoplasmic signalling domain of Msb2 regulated temperature-dependent activation of the CEK mitogen activated proteins kinase (MAPK) pathway. The extracellular glycosylated domain of Msb2 (100-900 amino acid residues) had a new and unexpected role in regulating the protein kinase C (PKC) pathway. Msb2 also regulated temperature-dependent induction of genes encoding regulators and targets of the unfolded protein response (UPR), which is a protein quality control (QC) pathway in the endoplasmic reticulum that controls protein folding/degradation in response to high temperature and other stresses. The heat shock protein and cell wall component Ssa1 was also required for hyphae formation and survival at 42°C and regulated the CEK and PKC pathways.

Differential expression and clinical relevance of MUC1 in renal cell carcinoma metastasis

PURPOSE

To determine the differential expression patterns and prognostic relevance of Mucin-1 (MUC1) expression in clear cell renal cell carcinoma (RCC) metastasis.

METHODS

Tissue microarrays (TMA) from samples of 151 RCC metastases, 61 primary RCCs and corresponding benign renal tissues were immunohistochemically stained for MUC1 and semi-quantitatively evaluated by immunoreactivity scores (IRS). MUC1 differential expression in metastasis, primary RCC and normal tissue were comparatively analyzed. Patient characteristics and clinical follow-up for patients with metastatic RCC (mRCC) were recorded. Correlations of MUC1 expression with mRCC survival were determined.

RESULTS

Median cytoplasmic expression was highest in benign tissue (IRS = 1.04). Primary RCC (0.50) and metastasis (0.12) showed significantly lower cytoplasmic staining intensity. Membranous expression in benign tissue was, however, significantly lower (0.21) compared with primary RCC (0.59) and metastasis (0.57). Notable differences of MUC1 cytoplasmic and membranous expression were observed between different metastasis sites. Significantly higher (P = 0.014) membranous expression was observed in pulmonary versus non-pulmonary lesions, while no significant differences of cytoplasmic MUC1 expression were observed. The prognostic relevance of MUC1 expression in metastatic RCC was limited.

CONCLUSIONS

MUC1 is differentially expressed in benign renal tissue, primary RCC and RCC metastasis. Membranous MUC1 expression was significantly elevated in pulmonary metastases compared to non-pulmonary lesions, which may reflect individual biology and putative response to MUC1-based anti-cancer therapy.

Identification of Potential Drug Targets in Cancer Signaling Pathways using Stochastic Logical Models

The investigation of vulnerable components in a signaling pathway can contribute to development of drug therapy addressing aberrations in that pathway. Here, an original signaling pathway is derived from the published literature on breast cancer models. New stochastic logical models are then developed to analyze the vulnerability of the components in multiple signalling sub-pathways involved in this signaling cascade. The computational results are consistent with the experimental results, where the selected proteins were silenced using specific siRNAs and the viability of the cells were analyzed 72 hours after silencing. The genes elF4E and NFkB are found to have nearly no effect on the relative cell viability and the genes JAK2, Stat3, S6K, JUN, FOS, Myc, and Mcl1 are effective candidates to influence the relative cell growth. The vulnerabilities of some targets such as Myc and S6K are found to vary significantly depending on the weights of the sub-pathways; this will be indicative of the chosen target to require customization for therapy. When these targets are utilized, the response of breast cancers from different patients will be highly variable because of the known heterogeneities in signaling pathways among the patients. The targets whose vulnerabilities are invariably high might be more universally acceptable targets.

Up-regulation of C1GALT1 promotes breast cancer cell growth through MUC1-C signaling pathway

Aberrant glycosylation is frequently observed in cancers. Core 1 β1,3-galactosyltransferase (C1GALT1) is an exclusive enzyme in humans that catalyzes the biosynthesis of core 1 O-glycan structure, Gal-GalNAc-O-Ser/Thr, whose expression is commonly up-regulated during tumorigenesis. Little is known about the function of C1GALT1 in breast cancer. This study aims to determine the correlation between C1GALT1 expression and breast cancer clinicopathological features and roles of C1GALT1 in breast cancer malignant phenotypes. Public databases and our data showed that C1GALT1 mRNA and C1GALT1 protein are frequently up-regulated in breast cancer; and increased C1GALT1 expression correlates with higher histological grade and advanced tumor stage. Overexpression of C1GALT1 enhanced breast cancer cell growth, migration, and invasion in vitro as well as tumor growth in vivo. Conversely, C1GALT1 knockdown suppressed these malignant phenotypes. Furthermore, C1GALT1 modulates O-glycan structures on Mucin (MUC) 1 and promotes MUC1-C/β-catenin signaling in breast cancer cells. These findings suggest that C1GALT1 enhances breast cancer malignant progression through promoting MUC1-C/β-catenin signaling pathway. Unveiling the function of C1GALT1 in breast cancer opens new insights to the roles of C1GALT1 and O-glycosylation in tumorigenesis and renders the potential of C1GALT1 as a target of novel therapeutic agent development.

Molecular alterations in gastric cancer with special reference to the early-onset subtype

Currently, gastric cancer (GC) is one of the most frequently diagnosed neoplasms, with a global burden of 723000 deaths in 2012. It is the third leading cause of cancer-related death worldwide. There are numerous possible factors that stimulate the pro-carcinogenic activity of important genes. These factors include genetic susceptibility expressed in a single-nucleotide polymorphism, various acquired mutations (chromosomal instability, microsatellite instability, somatic gene mutations, epigenetic alterations) and environmental circumstances (e.g., Helicobcter pylori infection, EBV infection, diet, and smoking). Most of the aforementioned pathways overlap, and authors agree that a clear-cut pathway for GC may not exist. Thus, the categorization of carcinogenic events is complicated. Lately, it has been claimed that research on early-onset gastric carcinoma (EOGC) and hereditary GC may contribute towards unravelling some part of the mystery of the GC molecular pattern because young patients are less exposed to environmental carcinogens and because carcinogenesis in this setting may be more dependent on genetic factors. The comparison of various aspects that differ and coexist in EOGCs and conventional GCs might enable scientists to: distinguish which features in the pathway of gastric carcinogenesis are modifiable, discover specific GC markers and identify a specific target. This review provides a summary of the data published thus far concerning the molecular characteristics of GC and highlights the outstanding features of EOGC.

Plasma levels and diagnostic utility of VEGF, MMP-9, and TIMP-1 in the diagnosis of patients with breast cancer

Vascular endothelial growth factor (VEGF), matrix metalloproteinase-9, and tissue inhibitor of metalloproteinase-1 may play a role in the pathogenesis of cancer disease. We investigated their levels and utility in comparison to cancer antigen (CA) 15-3 in patients with breast cancer (BC) and in relation to the control groups. The study included 100 women with BC, 50 patients with benign breast tumor, and 50 healthy women. The plasma levels of the tested parameters were determined using enzyme-linked immunosorbent assay, while CA 15-3 with chemiluminescent microparticle immunoassay. The results demonstrated significant differences in the concentration of the tested parameters and CA 15-3 between groups of patients with BC and healthy patients or patients with benign breast tumor. The plasma levels of VEGF and tissue inhibitor of metalloproteinase-1 were significantly higher in advanced tumor stages. The tested parameters were comparable to CA 15-3 values of the diagnostic sensitivity, specificity, the predictive values of positive and negative test results, and the area under the receiver-operating characteristic curve. The combined use of the tested parameters with CA 15-3 resulted in the increase in sensitivity, negative predictive value, and area under the receiver-operating characteristic curve, especially in the combination of VEGF with tumor marker (84%, 73%, 0.888, respectively). These findings suggest the usefulness of the tested parameters in the diagnosis of BC. VEGF, especially in combination with CA 15-3, showed the highest usefulness in the diagnosis of early BC.

Pre-clinical toxicity and immunogenicity evaluation of a MUC1-MBP/BCG anti-tumor vaccine

Mucin 1 (MUC1), as an oncogene, plays a key role in the progression and tumorigenesis of many human adenocarcinomas and is an attractive target in tumor immunotherapy. Our previous study showed that the MUC1-MBP/BCG anti-tumor vaccine induced a MUC1-specific Th1-dominant immune response, simulated MUC1-specific cytotoxic T lymphocyte killing activity, and could significantly inhibit MUC1-expression B16 cells' growth in mice. To help move the vaccine into a Phase I clinical trial, in the current study, a pre-clinical toxicity and immunogenicity evaluation of the vaccine was conducted. The evaluation was comprised of a single-dose acute toxicity study in mice, repeat-dose chronic toxicity and immunogenicity studies in rats, and pilot toxicity and immunogenicity studies in cynomolgus monkeys. The results showed that treatment with the MUC1-MBP/BCG anti-tumor vaccine did not cause any organ toxicity, except for arthritis or local nodules induced by BCG in several rats. Furthermore, the vaccine significantly increased the levels of IFN-γ in rats, indicating that Th1 cells were activated. In addition, the results showed that the MUC1-MBP/BCG anti-tumor vaccine induced a MUC1-specific IgG antibody response both in rats and cynomolgus monkeys. Collectively, these data are beneficial to move the MUC1-MBP/BCG anti-tumor vaccine into a Phase I clinical trial.

Biocompatible ELR-Based Polyplexes Coated with MUC1 Specific Aptamers and Targeted for Breast Cancer Gene Therapy

The search for new and biocompatible materials with high potential for improvement is a challenge in gene delivery applications. A cell type specific vector made of elastin-like recombinamer (ELR) and aptamers has been specifically designed for the intracellular delivery of therapeutic material for breast cancer therapy. A lysine-enriched ELR was constructed and complexed with plasmid DNA to give positively charged and stable polyplexes. Physical characterization of these polyplexes showed a particle size of around 140 nm and a zeta potential of approximately +40 mV. The incorporation of MUC1-specific aptamers into the polyplexes resulted in a slight decrease in zeta potential but increased cell transfection specificity for MCF-7 breast cancer cells with respect to a MUC1-negative tumor line. After showing the transfection ability of this aptamer-ELR vector which is facilitated mainly by macropinocytosis uptake, we demonstrated its application for suicide gene therapy using a plasmid containing the gene of the toxin PAP-S. The strategy developed in this work about using ELR as polymeric vector and aptamers as supplier of specificity to deliver therapeutic material into MUC1-positive breast cancer cells shows promising potential and continues paving the way for ELRs in the biomedical field.

Inhibition of MUC1-C Suppresses MYC Expression and Attenuates Malignant Growth in KRAS Mutant Lung Adenocarcinomas

Dysregulation of MYC expression is a hallmark of cancer, but the development of agents that target MYC has remained challenging. The oncogenic MUC1-C transmembrane protein is, like MYC, aberrantly expressed in diverse human cancers. The present studies demonstrate that MUC1-C induces MYC expression in KRAS mutant non-small cell lung cancer (NSCLC) cells, an effect that can be suppressed by targeting MUC1-C via shRNA silencing, CRISPR editing, or pharmacologic inhibition with GO-203. MUC1-C activated the WNT/β-catenin (CTNNB1) pathway and promoted occupancy of MUC1-C/β-catenin/TCF4 complexes on the MYC promoter. MUC1-C also promoted the recruitment of the p300 histone acetylase (EP300) and, in turn, induced histone H3 acetylation and activation of MYC gene transcription. We also show that targeting MUC1-C decreased the expression of key MYC target genes essential for the growth and survival of NSCLC cells, such as TERT and CDK4. Based on these results, we found that the combination of GO-203 and the BET bromodomain inhibitor JQ1, which targets MYC transcription, synergistically suppressed MYC expression and cell survival in vitro as well as tumor xenograft growth. Furthermore, MUC1 expression significantly correlated with that of MYC and its target genes in human KRAS mutant NSCLC tumors. Taken together, these findings suggest a therapeutic approach for targeting MYC-dependent cancers and provide the framework for the ongoing clinical studies addressing the efficacy of MUC1-C inhibition in solid tumors.

Dual-Color Emissive Upconversion Nanocapsules for Differential Cancer Bioimaging In Vivo

Early diagnosis of tumor malignancy is crucial for timely cancer treatment aimed at imparting desired clinical outcomes. The traditional fluorescence-based imaging is unfortunately faced with challenges such as low tissue penetration and background autofluorescence. Upconversion (UC)-based bioimaging can overcome these limitations as their excitation occurs at lower frequencies and the emission at higher frequencies. In this study, multifunctional silica-based nanocapsules were synthesized to encapsulate two distinct triplet-triplet annihilation UC chromophore pairs. Each nanocapsule emits different colors, blue or green, following a red light excitation. These nanocapsules were further conjugated with either antibodies or peptides to selectively target breast or colon cancer cells, respectively. Both in vitro and in vivo experimental results herein demonstrate cancer-specific and differential-color imaging from single wavelength excitation as well as far greater accumulation at targeted tumor sites than that due to the enhanced permeability and retention effect. This approach can be used to host a variety of chromophore pairs for various tumor-specific, color-coding scenarios and can be employed for diagnosis of a wide range of cancer types within the heterogeneous tumor microenvironment.

Applications of aptamers in targeted imaging: state of the art

Aptamers are single-stranded oligonucleotides with high affinity and specificity to the target molecules or cells, thus they can serve as an important category of molecular targeting ligand. Since their discovery, aptamers have been rapidly translated into clinical practice. The strong target affinity/selectivity, cost-effectivity, chemical versatility and safety of aptamers are superior to traditional peptides- or proteins-based ligands which make them unique choices for molecular imaging. Therefore, aptamers are considered to be extremely useful to guide various imaging contrast agents to the target tissues or cells for optical, magnetic resonance, nuclear, computed tomography, ultrasound and multimodality imaging. This review aims to provide an overview of aptamers' advantages as targeting ligands and their application in targeted imaging. Further research in synthesis of new types of aptamers and their conjugation with new categories of contrast agents is required to develop clinically translatable aptamer-based imaging agents which will eventually result in improved patient care.

Mucins and Wnt/β-catenin signaling in gastrointestinal cancers: an unholy nexus

The Wnt/β-catenin signaling pathway is indispensable for embryonic development, maintenance of adult tissue homeostasis and repair of epithelial injury. Unsurprisingly, aberrations in this pathway occur frequently in many cancers and often result in increased nuclear β-catenin. While mutations in key pathway members, such as β-catenin and adenomatous polyposis coli, are early and frequent occurrences in most colorectal cancers (CRC), mutations in canonical pathway members are rare in pancreatic ductal adenocarcinoma (PDAC). Instead, in the majority of PDACs, indirect mechanisms such as promoter methylation, increased ligand secretion and decreased pathway inhibitor secretion work in concert to promote aberrant cytosolic/nuclear localization of β-catenin. Concomitant with alterations in β-catenin localization, changes in mucin expression and localization have been documented in multiple malignancies. Indeed, numerous studies over the years suggest an intricate and mutually regulatory relationship between mucins (MUCs) and β-catenin. In the current review, we summarize several studies that describe the relationship between mucins and β-catenin in gastrointestinal malignancies, with particular emphasis upon colorectal and pancreatic cancer.

MUC1 upregulation promotes immune resistance in tumor cells undergoing brachyury-mediated epithelial-mesenchymal transition

Epithelial-mesenchymal transition (EMT) is a molecular and cellular program in which epithelial cells lose their well-differentiated phenotype and adopt mesenchymal characteristics. This process, which occurs naturally during embryogenesis, has also been shown to be associated with cancer progression and with tumor recurrence following conventional therapies. Brachyury is a transcription factor that mediates EMT during development, and is aberrantly expressed in various human cancers where it promotes tumor cell EMT, metastatic dissemination, and resistance to conventional therapies. We have recently shown that very high expression of brachyury can protect tumor cells against immune cell-mediated cytotoxicity. In seeking to elucidate mechanisms of immunotherapy resistance, we have discovered a novel positive association between brachyury and mucin-1 (MUC1). MUC1 is overexpressed in the majority of carcinomas, and it has been shown to mediate oncogenic signaling and confer resistance to genotoxic agents. We found that MUC1 is concomitantly upregulated in tumor cell lines that highly express brachyury due to an enhancement of MUC1 mRNA stability. Analysis of patient lung tumor tissues also identified a positive association between these two proteins in the majority of samples. Inhibition of MUC1 by siRNA-based gene silencing markedly enhanced the susceptibility of brachyury-expressing cancer cells to killing by tumor necrosis-related apoptosis-inducing ligand (TRAIL) and to perforin/granzyme-dependent lysis by immune cytotoxic cells. These studies confirm a protective role for MUC1 in brachyury-expressing cancer cells, and suggest that inhibition of MUC1 can restore the susceptibility of mesenchymal-like cancer cells to immune attack.

[Role of MUC1 Expression in Tumor Progression]

Mucin 1 (MUC1) is a multistructural and multifunctional protein that is involved in regulating diverse cellular activities. This strongly glycosylated transmembrane protein forms a mucous gel on the surface of epithelial cells that protects the cells from injury. MUC1 acts as a signaling molecule and transcription factor modulating metabolism and resistance to bacterial-induced inflammation. This article presents a review of the relationship between structural and functional changes of the MUC1 and the characteristics of cancer cells. The alteration in MUC1 expression level, a number of structural forms, protein glycosylation and localization occurs in cancer cells. These alterations lead to metabolic reprogramming associated with proliferation, resistance to hypoxia and angiogenesis which affects the survival of cancer cells. Furthermore, cancer cells can take advantage of MUC1 interaction with adhesion molecules for invasion and metastasis. Thus, MUC1 plays a key role both in the homeostasis of epithelial cells and in cancer progression. Understanding the role of MUC1 expression in tumor cells survival is important for the development of new monitoring and therapeutic approaches for the treatment MUC1 positive maligancies.

Targeting HGF/c-MET induces cell cycle arrest, DNA damage, and apoptosis for primary effusion lymphoma

Kaposi sarcoma-associated herpesvirus (KSHV) is a principal causative agent of primary effusion lymphoma (PEL) with a poor prognosis in immunocompromised patients. However, it still lacks effective treatment which urgently requires the identification of novel therapeutic targets for PEL. Here, we report that the hepatocyte growth factor (HGF)/c-MET pathway is highly activated by KSHV in vitro and in vivo. The selective c-MET inhibitor, PF-2341066, can induce PEL apoptosis through cell cycle arrest and DNA damage, and suppress tumor progression in a xenograft murine model. By using microarray analysis, we identify many novel genes that are potentially controlled by HGF/c-MET within PEL cells. One of the downstream candidates, ribonucleoside-diphosphate reductase subunit M2 (RRM2), also displays the promising therapeutic value for PEL treatment. Our findings provide the framework for development of HGF/c-MET-focused therapy and implementation of clinical trials for PEL patients.

Anti-MUC1 Antibody in Nipple Aspirate Fluids Correlates with Tumor Aggressiveness in Breast Cancer: A Feasibility Study

Antibodies against MUC1 are found in circulation of breast cancer (BC) patients. We hypothesized that anti-MUC1 antibodies might be present in even a higher concentration in nipple aspirate fluid (NAF) and could be used to predict aggressiveness of BC. Serum and NAF samples were collected from high risk lesions, BC, and healthy contralateral breasts. ELISA was used to measure the amount of IgG, IgM, and IgA against a tumor-specific MUC1 peptide derived from the extracellular tandem repeat domain of MUC1. Tumor characteristics were recorded prospectively; 120 NAF samples were obtained from a total of 77 women in the study. There was no significant difference of anti-MUC1 antibody levels compared to BC with other lesions. Anti-MUC1 IgG level in NAF was higher in triple negative tumors (P = 0.02); serum anti-MUC1 IgG levels were significantly higher in patients with ER (−) tumor and recurrent disease (P = 0.01); NAF anti-MUC1 IgA levels were significantly higher in patients with LVI and Her2-neu (+) tumors (P < 0.05). These results show that NAF could be a reliable biomarker to predict tumor aggressiveness in BC. A larger study will be needed to confirm these data and to investigate the potential of anti-MUC1 antibodies in NAF and serum to predict disease outcome.

MUC1 (CD227): a multi-tasked molecule

Mucin 1 (MUC1 [CD227]) is a high-molecular weight (>400 kDa), type I membrane-tethered glycoprotein that is expressed on epithelial cells and extends far above the glycocalyx. MUC1 is overexpressed and aberrantly glycosylated in adenocarcinomas and in hematological malignancies. As a result, MUC1 has been a target for tumor immunotherapeutic studies in mice and in humans. MUC1 has been shown to have anti-adhesive and immunosuppressive properties, protects against infections, and is involved in the oncogenic process as well as in cell signaling. In addition, MUC1 plays a key role in the reproductive tract, in the immune system (affecting dendritic cells, monocytes, T cells, and B cells), and in chronic inflammatory diseases. Evidence for all of these roles for MUC1 is discussed herein and demonstrates that MUC1 is truly a multitasked molecule.