MUC1 and the immunobiology of cancer

Armored modified vaccinia Ankara in cancer immunotherapy

Cancer immunotherapy relies on unleashing the patient´s immune system against tumor cells. Cancer vaccines aim to stimulate both the innate and adaptive arms of immunity to achieve durable clinical responses. Some roadblocks for a successful cancer vaccine in the clinic include the tumor antigen of choice, the adjuvants employed to strengthen antitumor-specific immune responses, and the risks associated with enhancing immune-related adverse effects in patients. Modified vaccinia Ankara (MVA) belongs to the family of poxviruses and is a versatile vaccine platform that combines several attributes crucial for cancer therapy. First, MVA is an excellent inducer of innate immune responses leading to type I interferon secretion and induction of T helper cell type 1 (Th1) immune responses. Second, it elicits robust and durable humoral and cellular immunity against vector-encoded heterologous antigens. Third, MVA has enormous genomic flexibility, which allows for the expression of multiple antigenic and costimulatory entities. And fourth, its replication deficit in human cells ensures a excellent safety profile. In this review, we summarize the current understanding of how MVA induces innate and adaptive immune responses. Furthermore, we will give an overview of the tumor-associated antigens and immunomodulatory molecules that have been used to armor MVA and describe their clinical use. Finally, the route of MVA immunization and its impact on therapeutic efficacy depending on the immunomodulatory molecules expressed will be discussed.

The potential applications of microparticles in the diagnosis, treatment, and prognosis of lung cancer

Microparticles (MPs) are 100–1000 nm heterogeneous submicron membranous vesicles derived from various cell types that express surface proteins and antigenic profiles suggestive of their cellular origin. MPs contain a diverse array of bioactive chemicals and surface receptors, including lipids, nucleic acids, and proteins, which are essential for cell-to-cell communication. The tumour microenvironment (TME) is enriched with MPs that can directly affect tumour progression through their interactions with receptors. Liquid biopsy, a minimally invasive test, is a promising alternative to tissue biopsy for the early screening of lung cancer (LC). The diverse biomolecular information from MPs provides a number of potential biomarkers for LC risk assessment, early detection, diagnosis, prognosis, and surveillance. Remodelling the TME, which profoundly influences immunotherapy and clinical outcomes, is an emerging strategy to improve immunotherapy. Tumour-derived MPs can reverse drug resistance and are ideal candidates for the creation of innovative and effective cancer vaccines. This review described the biogenesis and components of MPs and further summarised their main isolation and quantification methods. More importantly, the review presented the clinical application of MPs as predictive biomarkers in cancer diagnosis and prognosis, their role as therapeutic drug carriers, particularly in anti-tumour drug resistance, and their utility as cancer vaccines. Finally, we discussed current challenges that could impede the clinical use of MPs and determined that further studies on the functional roles of MPs in LC are required.

Update on the role of C1GALT1 in cancer (Review)

Cancer remains one of the most difficult diseases to treat. In the quest for early diagnoses to improve patient survival and prognosis, targeted therapies have become a hot research topic in recent years. Glycosylation is the most common posttranslational modification in mammalian cells. Core 1β1,3-galactosyltransferase (C1GALT1) is a key glycosyltransferase in the glycosylation process and is the key enzyme in the formation of the core 1 structure on which most complex and branched O-glycans are formed. A recent study reported that C1GALT1 was aberrantly expressed in tumors. In cancer cells, C1GALT1 is regulated by different factors. In the present review, the expression of C1GALT1 in different tumors and its possible molecular mechanisms of action are described and the role of C1GALT1 in cancer development is discussed.

Inter-cellular CRISPR screens reveal regulators of cancer cell phagocytosis

Monoclonal antibody therapies targeting tumour antigens drive cancer cell elimination in large part by triggering macrophage phagocytosis of cancer cells^1-7. However, cancer cells evade phagocytosis using mechanisms that are incompletely understood. Here we develop a platform for unbiased identification of factors that impede antibody-dependent cellular phagocytosis (ADCP) using complementary genome-wide CRISPR knockout and overexpression screens in both cancer cells and macrophages. In cancer cells, beyond known factors such as CD47, we identify many regulators of susceptibility to ADCP, including the poorly characterized enzyme adipocyte plasma membrane-associated protein (APMAP). We find that loss of APMAP synergizes with tumour antigen-targeting monoclonal antibodies and/or CD47-blocking monoclonal antibodies to drive markedly increased phagocytosis across a wide range of cancer cell types, including those that are otherwise resistant to ADCP. Additionally, we show that APMAP loss synergizes with several different tumour-targeting monoclonal antibodies to inhibit tumour growth in mice. Using genome-wide counterscreens in macrophages, we find that the G-protein-coupled receptor GPR84 mediates enhanced phagocytosis of APMAP-deficient cancer cells. This work reveals a cancer-intrinsic regulator of susceptibility to antibody-driven phagocytosis and, more broadly, expands our knowledge of the mechanisms governing cancer resistance to macrophage phagocytosis.

Changes in Protein Glycosylation in Head and Neck Squamous Cell Carcinoma

Glycosylation is an important posttranslational modification of proteins, and it has a profound influence on diverse life processes. An abnormal polysaccharide structure and mutation of the glycosylation pathway are closely correlated with human cancer progression. Glycoproteins such as EGFR, E-cadherin, CD44, PD-1/PD-L1, B7-H3 and Muc1 play important roles in the progression of head and neck squamous cell carcinoma (HNSCC), and their levels of glycosylation and changes in glycosyl structure are closely linked to HNSCC progression and malignant transformation. The regulation of protein glycosylation in HNSCC provides potential strategies to control cancer stem cell (CSC) subgroup expansion, epithelial-mesenchymal transition (EMT), tumor-related immunity escape and autophagy. Glycoproteins with altered glycosylation can be used as biomarkers for the early diagnosis, monitoring and prognostication of HNSCC. However, the glycobiology of cancer is still a new field that needs to be deeply studied, especially in HNSCC.

Efficacy and safety of the therapeutic cancer vaccine tecemotide (L-BLP25) in early breast cancer: Results from a prospective, randomised, neoadjuvant phase II study (ABCSG 34)

BACKGROUND

Immune-based strategies represent a promising approach in breast cancer (BC) treatment. The glycoprotein mucin-1 (MUC-1) is overexpressed in more than 90% of BC patients, and is targeted by the cancer vaccine tecemotide. We have investigated the efficacy and safety of tecemotide when added to neoadjuvant standard-of-care (SoC) treatment in early BC patients.

PATIENTS AND METHODS

A total of 400 patients with HER2-early BC were recruited into this prospective, multicentre, randomised 2-arm academic phase II trial. Patients received preoperative SoC treatment (chemotherapy or endocrine therapy) with or without tecemotide. Postmenopausal women with oestrogen receptor (ER)+++, or ER++ and Ki67 < 14%, and G1,2 tumours ('luminal A' tumours) received 6 months of letrozole. Postmenopausal patients with triple-negative, ER-/+/++ and Ki67 ≥ 14%, and with G3 tumours, as well as premenopausal patients, received four cycles of epirubicin/cyclophosphamide plus four cycles of docetaxel. Primary end-point was residual cancer burden (RCB; 0/I versus II/III) at surgery. Secondary end-points included pathological complete response (pCR), safety, and quality of life.

FINDINGS

We observed no significant difference in RCB 0/I rates between patients with (36.4%) and without (31.9%) tecemotide in the overall study population (p = 0.40) nor in endocrine and chemotherapy-treated subgroups (25.0% versus 13.3%, p = 0.17; 39.6% versus 37.8%, p = 0.75, respectively). The addition of tecemotide did not affect overall pCR rates (22.5% versus 17.4%, p = 0.23), MUC-1 expression, or tumour-infiltrating lymphocytes content. Tecemotide did not increase toxicity when compared to SoC therapy alone.

INTERPRETATION

Neoadjuvant tecemotide is safe, but does not improve RCB or pCR rates in patients receiving standard neoadjuvant therapy.

Multiplexed Detection of Autoantibodies to Glycopeptides Using Microarray

Protein microarray is a highly sensitive tool for antibody detection in serum. Monitoring of patients' antibody titers to specific antigens is increasingly employed in the diagnosis of several conditions, ranging from infectious diseases, allergies, autoimmune diseases, and cancer. In this protocol, we present a detailed method for enzymatic generation of disease-specific O-glycopeptides and how to monitor the antibody response to these in serum using microarray technology.

Association between the MUC1 rs4072037 Polymorphism and Risk of Gastric Cancer and Clinical Outcomes

Purpose

Mucin 1 (MUC1) was identified as a gastric cancer (GC) susceptibility gene by genome-wide association studies in Asians and candidate gene studies in Europeans. This study aimed to investigate the association between the MUC1 rs4072037 polymorphism and GC in terms of the Lauren classification and long-term clinical outcomes.

Materials and Methods

A total of 803 patients with GC and 816 unrelated healthy controls were enrolled in the study. The association between the MUC1 rs4072037 variant and GC histological types and clinical outcomes, including tumor recurrence and prognosis was investigated.

Results

The major A allele of rs4072037 was associated with increased GC risk (P<0.05). In subtype analysis, the association was most significant for diffuse-type GC (P<0.05) and in a dominant model (P<0.05), whereas there was no association with intestinal-type GC (P>0.05). Cox proportional hazards analysis revealed the heterozygote AG rs4072037 allele as an independent risk factor influencing tumor recurrence and disease-related death in diffuse-type GC (P<0.05). but not in intestinal-type GC (P>0.05).

Conclusions

The exonic single nucleotide polymorphism rs4072037 in MUC1 was associated with diffuse-type GC and was an independent risk factor influencing tumor recurrence and disease-related death in diffuse-type GC.

Breast cancer, placenta and pregnancy

BACKGROUND

Breast cancer is one of the most frequently diagnosed malignancies during pregnancy. Tumours often present characteristics of high malignancy and are hormone receptor negative/HER2 positive or triple negative. In general, pregnancy, including the postpartum period, is associated with a transiently increased risk of developing breast cancer but followed by a long-lasting protective period. Placental metastases are very rare and, thus far, breast cancer metastases in the foetal compartment have not been described. To discuss these apparently contradictory observations, this narrative review resumes immunological and hormonal alterations during pregnancy potentially affecting breast cancer risk as well as tumour growth and behaviour.

OBSERVATIONS

Upregulation of breast cancer-associated genes involved in immunological and reproductive processes has been observed in parous women and is potentially responsible for a transiently increased risk in pregnancy. In contrast, maternal immunisation and immunoglobulin production against antigens expressed on trophoblast cells, such as specific glycosylation patterns of mucin-1 or RCAS1-associated truncated glycans, seem to prevent breast cancer development in later years. Animal and human studies indicate that T cells are involved in these processes. Several placenta-derived factors, especially kisspeptin, have direct anti-tumour effects. The pregnancy-related increase of estrogen, progesterone, and other hormones influence growth and characteristics of breast cancer while the role of further placenta-secreted factors is still controversially discussed.

CONCLUSION

Several factors and cells are involved in altered breast cancer risk during and after pregnancy and have potential for developing novel treatment strategies in future.

Mid-region parathyroid hormone-related protein is a genome-wide chromatin-binding factor that promotes growth and differentiation of HB2 epithelial cells from the human breast

Human parathyroid hormone-related protein (PTHrP) is a polyhormone that undergoes proteolytic cleavage producing smaller peptides which exert diversified biological effects. PTHrP signalization is prominently involved in breast development and physiology, but the studies have been focused onto either N-terminal species or full-length protein introduced by gene transfer techniques. Our present work investigates for the first time the effect of the mid-region PTHrP secretory form, that is, the fragment [38-94], on HB2 non-tumoral breast epithelial cells. We examined viability/proliferation of cells grown in PTHrP-containing media supplemented with different serum concentration and on different substrates, extending our investigation to check whether (a) by analogy with MDA-MB231 cells, also HB2 cell chromatin possesses genome-wide binding sites for mid-region PTHrP, and (b) the peptide is endowed with modulating properties toward the expression of proliferation/differentiation signatures by HB2 cells. Our results indicate that mid-region PTHrP acts as a cell growth/differentiation stimulator in routine and "nutrient stress" culture conditions, accordingly reprogramming gene expression, and is able to bind to cytogenetic preparations from HB2 cells. This supports the concept that the physiological mechanisms involving PTHrP during breast development may include mature processed forms of the protein different from the N-terminal fragment. © 2018 BioFactors, 45(2):279-288, 2019.

Characterisation of tumour-derived microvesicles in cancer patients' blood and correlation with clinical outcome

To evaluate whether tumour-derived microvesicles (T-MV), originating from the plasma membrane, represent suitable cancer biomarkers, we isolated MV from peripheral blood samples of cancer patients with locally advanced and/or metastatic solid tumours (n = 330, including 79 head & neck cancers, 74 lung cancers, 41 breast cancers, 28 colorectal cancers and 108 with other cancer forms) and controls (n = 103). Whole MV preparations were characterised using flow cytometry. While MV carrying the tumour-associated proteins MUC1, EGFR and EpCAM were found to be enhanced in a tumour-subtype-specific way in patients' blood, expression of the matrix metalloproteinase inducer EMMPRIN was increased independent of tumour type. Higher levels of EMMPRIN⁺-MV correlated significantly with poor overall survival, whereas the other markers were prognostic only in specific tumour subgroups. By combining all four tumour-associated antigens, cancer patients were separated from healthy controls with an AUC of up to 0.85. Ex vivo, whole MV preparations from cancer patients, in contrast to those of controls, induced a tumour-supporting phenotype in macrophages and increased tumour cell invasion, which was dependent on the highly glycosylated isoform of EMMPRIN. In conclusion, the detection of T-MV in whole blood, even in minor amounts, is feasible with standard techniques, proves functionally relevant and correlates with clinical outcome.

Dual Role of the Extracellular Domain of Human Mucin MUC1 in Metastasis

Human mucin MUC1 plays an important role in cancer development. The increased level of this molecule expression during cancer cell progression induces metastasis and is associated with poor prognosis for patients. There is a large body of experimental data on the role of various functional domains of human mucin MUC1 in metastasis. While, the cytoplasmic domain determined to play a definitive role, the influence of extracellular domain on cancer cell invasiveness still remains unclear. The present paper reveals that the extracellular domain of MUC1 molecule consists of two functional subdomains-the region of tandem repeats (TR) and the region of irregular repeats (IR). We demonstrate the ability of each of these subdomains to alter the invasiveness of cancer cells. The presence of the MUC1 molecules containing TR subdomain (MUC1-TR) on the surface of low-invasive cancer cells leads to the increase in their transendothelial migration potency, while the addition of the IR subdomain to the MUC1-TR molecule (MUC1-IR-TR) restores their natural low invasiveness. J. Cell. Biochem. 118: 4002-4011, 2017. © 2017 Wiley Periodicals, Inc.

Interactions between the breast cancer-associated MUC1 mucins and C-type lectin characterized by optical tweezers

Carbohydrate–protein interactions govern many crucial processes in biological systems including cell recognition events. We have used the sensitive force probe optical tweezers to quantify the interactions occurring between MGL lectins and MUC1 carrying the cancer-associated glycan antigens mucins Tn and STn. Unbinding forces of 7.6±1.1 pN and 7.1±1.1 pN were determined for the MUC1(Tn)—MGL and MUC1(STn)—MGL interactions, at a force loading rate of ~40 pN/s. The interaction strength increased with increasing force loading rate, to 27.1±4.4 and 36.9±3.6 pN at a force loading rate of ~ 310 pN/s. No interactions were detected between MGL and MUC1(ST), a glycoform of MUC1 also expressed by breast carcinoma cells. Interestingly, this glycan (ST) can be found on proteins expressed by normal cells, although in this case not on MUC1. Additionally, GalNAc decorated polyethylene glycol displayed similar rupture forces as observed for MUC1(Tn) and MUC1(STn) when forced to unbind from MGL, indicating that GalNAc is an essential group in these interactions. Since the STn glycan decoration is more frequently found on the surface of carcinomas than the Tn glycan, the binding of MUC1 carrying STn to MGL may be more physiologically relevant and may be in part responsible for some of the characteristics of STn expressing tumours.

One Step Assembly of Thin Films of Carbon Nanotubes on Screen Printed Interface for Electrochemical Aptasensing of Breast Cancer Biomarker

Thin films of organic moiety functionalized carbon nanotubes (CNTs) from a very well-dispersed aqueous solution were designed on a screen printed transducer surface through a single step directed assembly methodology. Very high density of CNTs was obtained on the screen printed electrode surface, with the formation of a thin and uniform layer on transducer substrate. Functionalized CNTs were characterized by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET) surface area analyzer methodologies, while CNT coated screen printed transducer platform was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The proposed methodology makes use of a minimum amount of CNTs and toxic solvents, and is successfully demonstrated to form thin films over macroscopic areas of screen printed carbon transducer surface. The CNT coated screen printed transducer surface was integrated in the fabrication of electrochemical aptasensors for breast cancer biomarker analysis. This CNT coated platform can be applied to immobilize enzymes, antibodies and DNA in the construction of biosensor for a broad spectrum of applications.

TG4010: a vaccine with a therapeutic role in cancer

One of the strategies to enhance immune response against tumors has been the use of vaccines against tumor-associated antigens (TAAs). MUC1 is a TAA that is overexpressed in many malignancies being linked to worse prognosis. Moreover, tumor MUC1 is hypoglycosylated revealing new epitopes that are antigenic and potential T-cell targets. TG4010 is a recombinant viral vaccine targeting MUC1, also encoding for IL-2. TG4010 has been tested in Phase I-II trials demonstrating a consistent safety profile with mild local reactions as main side effect. These studies have confirmed immune responses to the vaccine product. Clinical efficacy has been observed mainly in patients with non-small-cell lung cancer in combination with chemotherapy. Peripheral activated NK cells are currently being validated as biomarkers of response.

Protective effect of naturally occurring anti-HER2 autoantibodies on breast cancer

Anti-HER2-autoantibodies (HER2-AAbs) are found in breast cancer patients as well as healthy individuals. However, the clinical relevance of the antibodies is unknown. We established an enzyme-linked immunosorbent assay with high sensitivity and quantified serum HER2-AAbs in 100 healthy women, 100 untreated patients with ductal carcinoma in situ (DCIS), and 500 untreated patients with invasive breast carcinoma (IBC). The associations between the levels of HER2-AAbs and breast cancer risk, and recurrence-free survival, were examined. High levels of HER2-AAbs were significantly associated with a reduced risk of DCIS (odds ratio [OR] 0.19, P = 4.6 × 10(-7)) or IBC (OR 0.31, P = 3.7 × 10(-7)). Subgroup analysis of IBC revealed a stronger association of HER2-AAbs with a reduced risk of the hormone receptor (HR)(-)/HER2(+) subtype (OR 0.12) than the other subtypes (HR(+)/HER2(-) [OR = 0.32], HR(+)/HER2(+) [OR 0.38], and HR(-)/HER2(-) [OR 0.29]). When we set the cutoff of HER2-AAbs at 20 ng/mL, recurrence-free survival of HER2-AAb-positive patients (N = 74) was significantly better than that of HER2-AAb-negative patients (N = 426) (P = 0.015). Univariate and multivariate analyses demonstrated that HER2-AAbs, as well as histological grade, were independently and significantly (P = 0.0065 and 0.049, respectively) associated with recurrence-free survival. Our exploratory study suggests a protective effect of naturally occurring HER2-AAbs on the development of primary and recurrent breast cancer. Further studies on HER2-AAbs are warranted.

Phase 1 clinical trial demonstrated that MUC1 positive metastatic seminal vesicle cancer can be effectively eradicated by modified Anti-MUC1 chimeric antigen receptor transduced T cells

Recent progress in chimeric antigen receptor-modified T-cell (CAR-T cell) technology in cancer therapy is extremely promising, especially in the treatment of patients with B-cell acute lymphoblastic leukemia. In contrast, due to the hostile immunosuppressive microenvironment of a solid tumor, CAR T-cell accessibility and survival continue to pose a considerable challenge, which leads to their limited therapeutic efficacy. In this study, we constructed two anti-MUC1 CAR-T cell lines. One set of CAR-T cells contained SM3 single chain variable fragment (scFv) sequence specifically targeting the MUC1 antigen and co-expressing interleukin (IL) 12 (named SM3-CAR). The other CAR-T cell line carried the SM3 scFv sequence modified to improve its binding to MUC1 antigen (named pSM3-CAR) but did not co-express IL-12. When those two types of CAR-T cells were injected intratumorally into two independent metastatic lesions of the same MUC1(+) seminal vesicle cancer patient as part of an interventional treatment strategy, the initial results indicated no side-effects of the MUC1 targeting CAR-T cell approach, and patient serum cytokines responses were positive. Further evaluation showed that pSM3-CAR effectively caused tumor necrosis, providing new options for improved CAR-T therapy in solid tumors.

RNAi-mediated gene silencing of ST6GalNAc I suppresses the metastatic potential in gastric cancer cells

BACKGROUND

ST6GalNAc I is a sialyltransferase controlling the expression of sialyl-Tn antigen (STn), which is overexpressed in several epithelial cancers, including gastric cancer, and is highly correlated with cancer metastasis. However, the functional contribution of ST6GalNAc I to development or progression of gastric cancer remains unclear. In this study, we investigated the effects of suppression of ST6GalNAc I on gastric cancer in vitro and in vivo.

METHODS

Gastric cancer cell lines were transfected with ST6GalNAc I siRNA and were examined by cell proliferation, migration, and invasion assays. We also evaluated the effect of ST6GalNAc I siRNA treatment in a peritoneal dissemination mouse model. The differences in mRNA levels of selected signaling molecules were analyzed by polymerase chain reaction (PCR) arrays associated with tumor metastasis in MKN45 cells. The signal transducer and activator of transcription 5b (STAT5b) signaling pathways that reportedly regulate the insulin-like growth factor-1 (IGF-1) were analyzed by Western blot.

RESULTS

ST6GalNAc I siRNA inhibited gastric cancer cell growth, migration, and invasion in vitro. Furthermore, intraperitoneal administration of ST6GalNAc I siRNA- liposome significantly inhibited peritoneal dissemination and prolonged the survival of xenograft model mice with peritoneal dissemination of gastric cancer. PCR array confirmed that suppression of ST6GalNAc I caused a significant reduction in expression of IGF-1 mRNA. Decreased IGF-1 expression in MKN45 cells treated with ST6GalNAc I siRNA was accompanied by reduced phosphorylation of STAT5b.

CONCLUSION

ST6GalNAc I may regulate the gene expression of IGF-1 through STAT5b activation in gastric cancer cells and may be a potential target for treatment of metastasizing gastric cancer.

Mucin 1-specific B cell immune responses and their impact on overall survival in breast cancer patients

Considering the diverse functions of B cells, responses to tumor-associated antigens (TAA) have been thought to be the main source of B cell-mediated antitumor immunity. Polymorphic epithelial mucin (MUC1) is considered one of the most specific TAA in patients with breast cancer. The present study aims to dissect the level and subclasses of naturally occurring anti-MUC1 antibodies in regard to tumor biologic parameters, clinical characteristics and overall survival. In 288 primary, non-metastatic breast cancer patients, pretreatment serum levels of anti-MUC1 immunoglobulin G (IgG) and its subclasses G1-4 as well as immunoglobulin M (IgM) were analyzed via ELISA. With respect to overall survival (Kaplan-Meier analysis), tumor biologic parameters as hormone receptor status, human epidermal growth factor receptor 2 (Her2), Ki-67 expression and tumor grading have been correlated as well as clinical characteristics as nodal involvement, tumor stage and patients' age at the time of diagnosis. Median follow-up time was 148 mo (IQR: 73.1-158.5 mo). A significant increase in IgG antibody titers was correlated highly significantly with an improved overall survival of patients. In multivariate analysis, total IgG proved to be an independent prognostic marker for overall survival (p = 0.002). IgG subclass analysis did not reveal any correlation of IgG1, IgG3 and IgG4 levels with overall survival, while increased immunoglobulin G2 (IgG2) values, although statistically not significant, tended to correlate with prolonged patient survival. MUC1-specific IgM antibodies were shown not to be predictive of overall survival. Altogether, humoral immune responses appear to play a crucial part in the tumor immunity of breast cancer patients. The present data confirms the positive impact of tumor-specific IgG on prolonged overall survival in breast cancer patients. MUC1-antibody testing might be a useful tool to identify high-risk patients who may need adjuvant therapy and potentially might benefit from MUC1-directed immunotherapy.

Molecular Dynamics Simulation Analysis of Anti-MUC1 Aptamer and Mucin 1 Peptide Binding

Aptasensors utilize aptamers as bioreceptors. Aptamers are highly efficient, have a high specificity and are reusable. Within the biosensor the aptamers are immobilized to maximize their access to target molecules. Knowledge of the orientation and location of the aptamer and peptide during binding could be gained through computational modeling. Experimentally, the aptamer (anti-MUC1 S2.2) has been identified as a bioreceptor for breast cancer biomarker mucin 1 (MUC1) protein. However, within this protein lie several peptide variants with the common sequence APDTRPAP that are targeted by the aptamer. Understanding orientation and location of the binding region for a peptide-aptamer complex is critical in their biosensor applicability. In this study, we investigate through computational modeling how this peptide sequence and its minor variants affect the peptide-aptamer complex binding. We use molecular dynamics simulations to study multiple peptide-aptamer systems consisting of MUC1 (APDTRPAP) and MUC1-G (APDTRPAPG) peptides with the anti-MUC1 aptamer under similar physiological conditions reported experimentally. Multiple simulations of the MUC1 peptide and aptamer reveal that the peptide interacts between 3' and 5' ends of the aptamer but does not fully bind. Multiple simulations of the MUC1-G peptide indicate consistent binding with the thymine loop of the aptamer, initiated by the arginine residue of the peptide. We find that the binding event induces structural changes in the aptamer by altering the number of hydrogen bonds within the aptamer and establishes a stable peptide-aptamer complex. In all MUC1-G cases the occurrence of binding was confirmed by systematically studying the distance distributions between peptide and aptamers. These results are found to corroborate well with experimental study reported in the literature that indicated a strong binding in the case of MUC1-G peptide and anti-MUC1 aptamer. Present MD simulations highlight the role of the arginine residue of MUC1-G peptide in initiating the binding. The addition of the glycine residue to the peptide, as in the case of MUC1-G, is shown to yield a stable binding. Our study clearly demonstrates the ability of MD simulations to obtain molecular insights for peptide-aptamer binding, and to provide details on the orientation and location of binding between the peptide-aptamer that can be instrumental in biosensor development.

Synthesis and cell-selective antitumor properties of amino acid conjugated tumor-associated carbohydrate antigen-coated gold nanoparticles

The Thomsen Friedenreich antigen (TFag) disaccharide is a tumor-associated carbohydrate antigen (TACA) found primarily on carcinoma cells and rarely expressed in normal tissue. The TFag has been shown to interact with Galectin-3 (Gal-3), one in a family of β-galactoside binding proteins. Galectins have a variety of cellular functions, and Gal-3 has been shown to be the sole galectin with anti-apoptotic activity. We have previously prepared gold nanoparticles (AuNP) coated with the TFag in various presentations as potential anti-adhesive therapeutic tools or antitumor vaccine platforms. Here we describe the synthesis of TFag-glycoamino acid conjugates attached to gold nanoparticles through a combined alkane/PEG linker, where the TFag was attached to either a serine or threonine amino acid. Particles were fully characterized by a host of biophysical techniques, and along with a control particle carrying hydroxyl-terminated linker units, were evaluated in both Gal-3 positive and negative cell lines. We show that the particles bearing the saccharides selectively inhibited tumor cell growth of the Gal-3 positive cells significantly more than the Gal-3 negative cells. In addition, the threonine-attached TF particles were more potent than the serine-attached constructs. These results support the use of AuNP as antitumor therapeutic platforms, targeted against cell lines that express specific lectins that interact with TFag.

Mechanisms of antitumor and immune-enhancing activities of MUC1/sec, a secreted form of mucin-1

Mucin 1 (MUC1) is a polymorphic type 1 transmembrane protein found on the apical surface of normal cells lining the lumen of ducts and glands. Mucins are thought to provide mucosal protection from environmental exposures and carcinogens. An altered form of the MUC1 glycoprotein, which is hypoglycosylated, is expressed in several types of human cancers. In our laboratory, we have found that transfection of a murine mammary tumor cell line with a human secreted isoform of MUC1 rendered these DA-3 cells (DA-3/sec) incapable of growing in intact BALB/c mice. In contrast, implantation of DA-3 cells transfected with the human transmembrane isoform of MUC1 (DA-3/TM), resulted in tumor formation and ultimately death of the animals, similar to the DA-3 parental line. Importantly, inoculation of the DA-3/sec cells in immunodeficient nude mice resulted in tumor formation, indicating that the MUC1/sec molecule's antitumor activity is immunologically controlled. In this review, we summarize the studies we have performed to elucidate possible mechanisms for the immune-mediated antitumor effect of MUC1/sec and/or a unique peptide present in this mucin. Understanding these mechanisms may provide new immunotherapeutic approaches that could be used to target different types of cancer.

Altered glycosylation of MUC1 influences its association with CIN85: the role of this novel complex in cancer cell invasion and migration

MUC1 is a transmembrane glycoprotein abnormally expressed in human adenocarcinomas. The extracellular domain of MUC1 contains a variable number of tandem repeats (VNTR) region that is extensively O-glycosylated in normal epithelia and underglycosylated in tumor cells. This change in posttranslational modification of MUC1 leads to changes in its normal functions including, we hypothesized, its interaction with other molecules. We identified CIN85, an adaptor protein involved in multiple cellular processes including signal transduction, cytoskeletal remodeling and cancer cell invasion, as one of several proteins that associate with MUC1 in tumor cells. CIN85 associates with both the cytosolic tail and the extracellular VNTR of MUC1. Co-immunoprecipitation and confocal immunofluorescence confirmed that MUC1 and CIN85 co-localize primarily at the plasma membrane but the complex can be found also in the cytosol and on the cytoskeleton. MUC1 and CIN85 are both over-expressed in early as well as advanced clinical stages of breast cancer and co-localize on invadopodia-like structures implicated in cell invasion. siRNA-mediated silencing of CIN85 and/or MUC1 revealed that MUC1 enhances CIN85-dependent breast cancer cell migration and invasion in vitro. However, ectopic expression of MUC1 enhances the motility induced by CIN85. When tested in vivo in a tumor metastasis model of B16 melanoma, mice injected with CIN85-depleted melanoma cells exhibited few or no lung metastasis and, similarly to the in vitro results, overexpression of MUC1 recovered the shCIN85-reduced metastatic process. Our findings implicate this newly identified CIN85/MUC1 complex associated with invadopodia-related molecules in promoting the invasive and metastatic potential of breast cancer.

Regulation of the metastatic cell phenotype by sialylated glycans

Tumor cells exhibit striking changes in cell surface glycosylation as a consequence of dysregulated glycosyltransferases and glycosidases. In particular, an increase in the expression of certain sialylated glycans is a prominent feature of many transformed cells. Altered sialylation has long been associated with metastatic cell behaviors including invasion and enhanced cell survival; however, there is limited information regarding the molecular details of how distinct sialylated structures or sialylated carrier proteins regulate cell signaling to control responses such as adhesion/migration or resistance to specific apoptotic pathways. The goal of this review is to highlight selected examples of sialylated glycans for which there is some knowledge of molecular mechanisms linking aberrant sialylation to critical processes involved in metastasis.

Association of genetic polymorphisms at 1q22 but not 10q23 with gastric cancer in a southern Chinese population

OBJECTIVE

Data from a recent genome-wide association studiesy of gastric cancer (GC) and oesophageal squamous cell carcinoma in Chinese living in the Taihang Mountains of north-central China suggest that 1q22 and 10q23 are susceptibility-associated regions for GC. However, this has not been confirmed in southern Chinese populations. The aim of this study was to investigate whether these polymorphisms at 1q22 and 10q23 are associated with the risk of GC in a southern Chinese population.

METHODS

We selected seven top significant associated single nucleotide polymorphisms (SNPs) at 1q22 and 10q23 and conducted a population-based case- control study in a southern Chinese population. Genotypes were determined using MassARRAYTM system (Sequenome, San Diego, CA).

RESULTS

Two SNPs at 1q22, rs4072037 and rs4460629, were significantly associated with a reduced risk of GC, best fitting the dominant genetic model. Logistic regression models adjusted for age and sex showed that rs4072037 AG and GG (OR=0.64, P=0.017, compared with AA) and rs4460629 CT and TT (OR=0.54, P=0.0016, compared with TT) significantly reduced the risk of GC. However, no significant results for the five SNPs at 10q23 were obtained in this study.

CONCLUSION

These outcomes indicate that 1q22 is associated with GC susceptibility in this southern Chinese population, while an association for the locus at 10q23 was not confirmed.

Chemo-enzymatic production of O-glycopeptides for the detection of serum glycopeptide antibodies

Protein microarray is a highly sensitive tool for antibody detection in serum. Monitoring of patients' antibody titers to specific antigens is increasingly employed in the diagnosis of several conditions, ranging from infectious diseases, allergies, autoimmune diseases, and cancer. In this protocol we present a detailed method for enzymatic generation of disease-specific O-glycopeptides and how to monitor the antibody response to these in serum using microarray technology.

Relationships among serum CA15-3 tumor marker, TNM staging, and estrogen and progesterone receptor expression in benign and malignant breast lesions

Serum tumor marker CA15-3 is widely used in follow-up for assessment of breast cancer prognosis. The aim of this study was to evaluate levels among healthy females and patients, to assess differences with tumor stage and grade, and to determine the relationship with estrogen and progesterone receptor expression. One hundred and thirty six Jordanian females were enrolled in this study: Forty-five were healthy females; seventy-two were diagnosed with breast cancer and nineteen diagnosed with benign breast lesions. Elevated serum CA15-3 level was significantly observed among breast cancer patients (37.95±6.65) compared to both healthy (14.97±0.8) and benign females (12.30±1.55), but no significant association was detected between serum CA15-3 level and age of cancer onset, menarche age, menopause age, parity and BMI. Decreased CA15-3 level was significantly associated with hormone therapy and oral contraceptive consumption among breast cancer patients. Significantly elevated CA15-3 serum levels were found among grade II, III and stage II and III breast cancer females compared to normal healthy females. Elevated CA15-3 serum levels were also found among ER+/PR+ (54.242±7.89) and ER+/PR- (37.08±8.22) compared to healthy control females.

Aberrantly glycosylated MUC1 is expressed on the surface of breast cancer cells and a target for antibody-dependent cell-mediated cytotoxicity

Protein glycosylation often changes during cancer development, resulting in the expression of cancer-associated carbohydrate antigens. In particular mucins such as MUC1 are subject to these changes. We previously identified an immunodominant Tn-MUC1 (GalNAc-α-MUC1) cancer-specific epitope not covered by immunological tolerance in MUC1 humanized mice and man. The objective of this study was to determine if mouse antibodies to this Tn-MUC1 epitope induce antibody-dependent cellular cytotoxicity (ADCC) pivotal for their potential use in cancer immunotherapy. Binding affinity of mAb 5E5 directed to Tn-MUC1 was investigated using BiaCore. The availability of Tn-MUC1 on the surface of breast cancer cells was evaluated by immunohistochemistry, confocal microscopy, and flow cytometry, followed by in vitro assessment of antibody-dependent cellular cytotoxicity by mAb 5E5. Biacore analysis demonstrated high affinity binding (KD = 1.7 nM) of mAb 5E5 to its target, Tn-MUC1. Immunolabelling with mAb 5E5 revealed surface expression of the Tn-MUC1 epitope in breast cancer tissue and cell lines, and mAb 5E5 induced ADCC in two human breast cancer cell lines, MCF7 and T47D. Aberrantly glycosylated MUC1 is expressed on the surface of breast cancer cells and a target for antibody-dependent cell-mediated cytotoxicity suggesting that antibodies targeting glycopeptide epitopes on mucins are strong candidates for cancer-specific immunotherapies.

Association of 10q23 with colorectal cancer in a Chinese population

Recently, a genome-wide association study of gastric cancer (GC) reported the significant association of seven genetic variants (rs4072037 and rs4460629 on 1q22; rs753724, rs11187842, rs3765524, rs2274223, and rs3781264 on 10q23) with GC in a Chinese population. These findings were confirmed in a subsequent independent study. However, it remains unknown whether these loci are associated with an increased risk of colorectal cancer (CRC). This study was to test whether the seven single nucleotide polymorphisms (SNPs) associated with GC were also associated with CRC in a Chinese population. The seven SNPs were genotyped using MassARRAY system. Allelic, genotypic, and haplotypic associations of the SNPs with CRC were investigated using χ(2) tests and logistic regression analysis. The SNPs rs3765524 and rs2274223, located on 10q23, were found to have significant protective effects against CRC, with equal odds ratios per allele. The two SNPs located on 1q22 (rs4072037 and rs4460629) showed a weak association with CRC. No significant association was identified with CRC for the remaining three SNPs located on 10q23 (rs753724, rs11187842, and rs3781264). These results suggest that rs3765524 and rs2274223 on 10q23 are associated with a protective effect against CRC in a Chinese population.

Elucidation of the sugar recognition ability of the lectin domain of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase 3 by using unnatural glycopeptide substrates

Mucin-type glycosylation [α-N-acetyl-D-galactosamine (α-GalNAc)-O-Ser/Thr] on proteins is initiated biosynthetically by 16 homologous isoforms of GalNAc-Ts (uridine diphosphate-GalNAc:polypeptide N-acetylgalactosaminyltransferases). All the GalNAc-Ts consist of a catalytic domain and a lectin domain. Previous reports of GalNAc-T assays toward peptides and α-GalNAc glycopeptides showed that the lectin domain recognized the sugar on the substrates and affected the reaction; however, the details are not clear. Here, we report a new strategy to give insight on the sugar recognition ability and the function of the GalNAc-T3 lectin domain using chemically synthesized natural-type (α-GalNAc-O-Thr) and unnatural-type [β-GalNAc-O-Thr, α-Fuc-O-Thr and β-GlcNAc-O-Thr] MUC5AC glycopeptides. GalNAc-T3 is one of isoforms expressed in various organs, its substrate specificity extensively characterized and its anomalous expression has been identified in several types of cancer (e.g. pancreas and stomach). The glycopeptides used in this study were designed based on a preliminary peptide assay with a sequence derived from the MUC5AC tandem repeat. Through GalNAc-T3 and lectin-inactivated GalNAc-T3, competition assays between the glycopeptide substrates and product analyses (MALDI-TOF MS, RP-HPLC and ETD-MS/MS), we show that the lectin domain strictly recognized GalNAc on the substrate and this specificity controlled the glycosylation pathway.

Lipopolysaccharide priming enhances expression of effectors of immune defence while decreasing expression of pro-inflammatory cytokines in mammary epithelia cells from cows

Background

Udder infections with environmental pathogens like Escherichia coli are a serious problem for the dairy industry. Reduction of incidence and severity of mastitis is desirable and mild priming of the immune system either through vaccination or with low doses of immune stimulants such as lipopolysaccharide LPS was previously found to dampen detrimental effects of a subsequent infection. Monocytes/macrophages are known to develop tolerance towards the endotoxin LPS (endotoxin tolerance, ET) as adaptation strategy to prevent exuberant inflammation.

We have recently observed that infusion of 1 μg of LPS into the quarter of an udder effectively protected for several days against an experimentally elicited mastitis. We have modelled this process in primary cultures of mammary epithelial cells (MEC) from the cow. MEC are by far the most abundant cells in the healthy udder coming into contact with invading pathogens and little is known about their role in establishing ET.

Results

We primed primary MEC cultures for 12 h with LPS (100 ng/ml) and stimulated three cultures either 12 h or 42 h later with 10⁷/ml particles of heat inactivated E. coli bacteria for six hours. Priming-related alterations in the global transcriptome of those cells were quantified with Affymetrix microarrays. LPS priming alone caused differential expression of 40 genes and mediated significantly different response to a subsequent E. coli challenge of 226 genes. Expression of 38 genes was enhanced while that of 188 was decreased. Higher expressed were anti-microbial factors (β-defensin LAP, SLPI), cell and tissue protecting factors (DAF, MUC1, TGM1, TGM3) as well as mediators of the sentinel function of MEC (CCL5, CXCL8). Dampened was the expression of potentially harmful pro-inflammatory master cytokines (IL1B, IL6, TNF-α) and immune effectors (NOS2, matrix metalloproteases). Functional network analysis highlighted the reduced expression of IL1B and of IRF7 as key to this modulation.

Conclusion

LPS-primed MEC are fitter to repel pathogens and better protected against misguided attacks of the immune response. Attenuated is the exuberant expression of factors potentially promoting immunopathological processes. MEC therefore recapitulate many aspects of ET known so far from professional immune cells.

MUC1 protein expression in tumor cells regulates transcription of proinflammatory cytokines by forming a complex with nuclear factor-κB p65 and binding to cytokine promoters: importance of extracellular domain

MUC1 is a transmembrane glycoprotein abnormally expressed in all stages of development of human adenocarcinomas. Overexpression and hypoglycosylation of MUC1 in cancer cells compared with normal epithelial cells are likely to alter its function and affect the behavior of cancer cells. The extracellular domain, specifically the highly O-glycosylated VNTR (variable number of tandem repeats) region, plays an important role in cell-cell communication; however, we show here that it also participates intracellularly in activation of the NF-κB pathway. Transfection of MUC1(-) tumor cells with cDNA encoding MUC1 with 22 tandem repeats (MUC1/22TR) or two tandem repeats (MUC1/2TR) or two isoforms that lack the VNTR region (MUC1/Z and MUC1/Y) showed that the highest expression levels of NF-κB family members correlated with the presence of VNTR and the highest number of tandem repeats. Because expression of MUC1 with VNTR on tumors was previously associated with chemotactic activity for cells of the innate immune system, we investigated the influence of MUC1 expression on the NF-κB-dependent transcriptional regulation of proinflammatory cytokines. ChIP and real-time PCR experiments revealed that MUC1/22TR up-regulated IL-6 and TNF-α expression by binding to their promoter regions in a NF-κB p65-dependent manner in both MUC1-transfected and human breast cancer cells that express endogenous MUC1. This newly detected complex of MUC1 and p65 is a novel mechanism that tumors can use to promote inflammation and cancer development.

Glycomechanics of the metastatic cascade: tumor cell-endothelial cell interactions in the circulation

Hydrodynamic shear force plays an important role in the leukocyte adhesion cascade that involves the tethering and rolling of cells along the endothelial layer, their firm adhesion or arrest, and their extravasation or escape from the circulatory system by inducing passive deformation, or cell flattening, and microvilli stretching, as well as regulating the expression, distribution, and conformation of adhesion molecules on leukocytes and the endothelial layer. Similarly, the dissemination of circulating tumor cells (CTCs) from the primary tumor sites is believed to involve tethering, rolling, and firm adhesion steps before their eventual extravasation which leads to secondary tumor sites (metastasis). Of particular importance to both the leukocyte adhesion cascade and the extravasation of CTCs, glycoproteins are involved in all three steps (capture, rolling, and firm adhesion) and consist of a variety of important selectin ligands. This review article provides an overview of glycoprotein glycosylation associated with the abnormal glycan expression on cancer cell surfaces, where well-established and novel selectin ligands that are cancer related are discussed. An overview of computational approaches on the effects of fluid mechanical force on glycoprotein mediated cancer cell rolling and adhesion is presented with a highlight of recent flow-based and selectin-mediated cell capturing/enriching devices. Finally, as an important branch of the glycoprotein family, mucins, specifically MUC1, are discussed in the context of their aberrant expression on cancer cells and their role as cancer cell adhesion molecules. Since metastasis relies heavily on glycoprotein interactions in the bloodstream where the fluid shear stress highly regulates cell adhesion forces, it is important to study and understand the glycomechanics of all relevant glycoproteins (well-established and novel) as they relate to the metastatic cascade.

Nanobody-based chimeric receptor gene integration in Jurkat cells mediated by φC31 integrase

The crucial role of T lymphocytes in anti-tumor immunity has led to the development of novel strategies that can target and activate T cells against tumor cells. Recombinant DNA technology has been used to generate non-MHC-restricted chimeric antigen receptors (CARs). Here, we constructed a panel of recombinant CAR that harbors the anti-MUC1 nanobody and the signaling and co-signaling moieties (CD3ζ/CD28) with different spacer regions derived from human IgG3 with one or two repeats of the hinge sequence or the hinge region of FcγRII. The PhiC31 integrase system was employed to investigate if the recombination efficiency could be recruited for high and stable expression of T cell chimeric receptor genes. The effect of nuclear localization signal (NLS) and two different promoters (CMV and CAG) on efficacy of PhiC31 integrase in human T cell lines was evaluated. The presence of integrase in combination with NLS, mediated up to 7.6 and 8.5 fold increases in CAR expression in ZCHN-attB and ZCHHN-attB cassette integrated T cells, respectively. Our results showed that highly efficient and stable transduction of the Jurkat cell line by PhiC31 integrase is a feasible modality for generating anti-cancer chimeric T cells for use in cancer immunotherapy.

Tumour-associated glycan modifications of antigen enhance MGL2 dependent uptake and MHC class I restricted CD8 T cell responses

We recently showed that MGL2 specifically binds tumour-associated glycan N-acetylgalactosamine (GalNAc). We here demonstrate that modification of an antigen with tumour-associated glycan GalNAc, targets antigen specifically to the MGL2 on bone marrow derived (BM)-DCs and splenic DCs. Glycan-modification of antigen with GalNAc that mimics tumour-associated glycosylation, promoted antigen internalisation in DCs and presentation to CD4 T cells, as well as differentiation of IFN-γ producing CD4 T cells. Furthermore, GalNAc modified antigen enhanced cross-presentation of both BM-DCs and primary splenic DCs resulting in enhanced antigen specific CD8 T cell responses. Using MyD88-TRIFF(-/-) BM-DCs we demonstrate that the enhanced cross-presentation of the GalNAc modified antigen is TLR independent. Our data strongly suggest that tumour-associated GalNAc modification of antigen targets MGL on DCs and greatly enhances both MHC class II and class I presentation in a TLR independent manner.

Nanobody; an old concept and new vehicle for immunotargeting

The use of antibodies in cancer therapy has come a long way since the day Paul Ehrlich described the concept and Kohler and Milstein devised the hybridoma technology to bring this theory to reality. The synthesis of murine monoclonal antibodies (mAbs) was the first success in this field, leading to the invention of chimerization, the production of variable fragments (Fv) with the progression to domain antibodies (dAb) and later humanization technologies to maximize the clinical utility of murine mAbs. It was just by chance that dAbs were found to exist in ?heavy chain? immunoglobulins from Camelidae family and cartilaginous fish. These unique antibody fragments interact with antigen by virtue of only one single variable domain, referred to as VHH or nanobody. Several characteristics make nanobody use superior to the abovementioned antibodies. They are non-immunogenic and show high thermal and chemical stability. There are several reports of raising specific nanobodies against enzymes, haptens, pathogens, toxins and tumor markers, which are outlined in this paper. All these characteristics make them strong candidates as targeting agents for cancer therapy.

Pancreatic cyst fluid and serum mucin levels predict dysplasia in intraductal papillary mucinous neoplasms of the pancreas

INTRODUCTION

There are no reliable markers of dysplasia in patients with incidentally discovered intraductal papillary mucinous neoplasms of the pancreas (IPMN). IPMN dysplasia may be associated with mucin protein (MUC) expression and histopathologic subtype. We hypothesize that MUC expression in cyst fluid and serum can identify lesions with high risk of malignancy.

METHODS

Cyst fluid and serum were collected from 40 patients during pancreatectomy for IPMN between 2005 and 2009. Samples were grouped into low-risk (low-grade or moderate dysplasia, n = 21) and high-risk groups (high-grade dysplasia or carcinoma, n = 19). Mucin expression (MUC1, MUC2, MUC4, and MUC5AC) was assessed utilizing enzyme-linked immunosorbent assays.

RESULTS

MUC2 and MUC4 cyst fluid concentrations were elevated in high-risk versus low-risk groups (10 ± 3.0 ng/ml vs. 4.4 ± 1.2 ng/ml, p = 0.03; 20.6 ± 10.6 ng/ml vs. 4.5 ± 1.4 ng/ml, p = 0.03, respectively). Corresponding serum samples revealed higher levels of MUC5AC in high-risk compared with low-risk patients (19.9 ± 9.3 ng/ml vs. 2.2 ± 1.1 ng/ml, p = 0.04). Histopathologic subtype was significantly associated with grade of dysplasia, and the intestinal subtype displayed increased MUC2 cyst fluid concentrations (13.8 ± 6.5 ng/ml vs. 4.1 ± 0.9 ng/ml, p = 0.02).

CONCLUSIONS

In this study, high-risk IPMN showed elevated cyst fluid concentrations of MUC2 and MUC4, and increased serum levels of MUC5AC. High-risk IPMN also displayed a distinct mucin expression profile in specific histologic subtypes. These data, if validated, may allow surgeons to more appropriately select patients for operative resection.

Flow cytometry-based assay to evaluate human serum MUC1-Tn antibodies

Mucin-1 (MUC1) is a heavily O-glycosylated, transmembrane protein that is expressed on the apical surface of most secretory epithelia. In malignantly transformed epithelia, MUC1 has lost its apical distribution, is underglycosylated and is secreted into the circulation. Due to the underglycosylation of MUC1, cancer-specific MUC1-Tn/STn antigens, which are highly immunogenic, become exposed. We aimed at developing a system that allows detection of antibodies directed to the native form of MUC1 and the underglycosylated MUC1-Tn epitopes. To this end, we made use of the Chinese Hamster Ovary (CHO) ldlD cell line stably transfected with MUC1. This cell line has a glycosylation defect, which can be reversed by addition of different monosaccharides to the cell culture and enables the production of cells expressing the MUC1-Tn glycoforms. After validation with glycospecific antibodies, the CHO-ldlD MUC1 system was used to detect serum MUC1 and MUC1-Tn antibodies. Using this system, we could confirm the presence of MUC1-Tn antibodies in the serum of a patient vaccinated with a truncated MUC1 peptide. This indicates that the CHO-ldlD MUC1 system represents a flow cytometry-based technique to detect antibodies binding to the underglycosylated MUC1 protein. This cellular system is complementary to the previously published methods to detect MUC1 serum antibodies, since the antibodies to the native protein are evaluated and therefore it can be effectively used for MUC1 antibody monitoring in vaccination studies as well as for functional assays.

MUC1 immunotherapy

The overexpression and aberrant glycosylation of MUC1 is associated with a wide variety of cancers, making it an ideal target for immunotherapeutic strategies. This review highlights the main avenues of research in this field, focusing on adenocarcinomas, from the preclinical to clinical; the problems and possible solutions associated with each approach; and speculates on the direction of MUC1 immunotherapeutic research over the next 5-10 years.

A high-throughput O-glycopeptide discovery platform for seromic profiling

Biomarker microarrays are becoming valuable tools for serological screening of disease-associated autoantibodies. Post-translational modifications (PTMs) such as glycosylation extend the range of protein function, and a variety of glycosylated proteins are known to be altered in disease progression. Here, we have developed a synthetic screening microarray platform for facile display of O-glycosylated peptides (O-PTMs). By introduction of a capping step during chemical solid-phase glycopeptide synthesis, selective enrichment of N-terminal glycopeptide end products was achieved on an amine-reactive hydrogel-coated microarray glass surface, allowing high-throughput display of large numbers of glycopeptides. Utilizing a repertoire of recombinant glycosyltransferases enabled further diversification of the array libraries in situ and display of a new level of potential biomarker candidates for serological screening. As proof-of-concept, we have demonstrated that MUC1 glycopeptides could be assembled and used to detect autoantibodies in vaccine-induced disease-free breast cancer patients and in patients with confirmed disease at time of diagnosis.

Detection of circulating anti-mucin 1 (MUC1) antibodies in breast tumor patients by indirect enzyme-linked immunosorbent assay using a recombinant MUC1 protein containing six tandem repeats and expressed in Escherichia coli

Mucin 1 (MUC1), a tumor-associated antigen, is a transmembrane glycoprotein expressed by normal epithelial cells and overexpressed by carcinomas of epithelial origin. Autoantibodies against MUC1 are often found in circulation, either free or bound to immune complexes, which might contribute to limit tumor outgrowth and dissemination by antibody-dependent cell-mediated cytotoxicity, and were found favorably predictive of survival in early breast cancer patients. There is no commercial enzyme-linked immunosorbent assay (ELISA) kit for detecting the anti-MUC1 antibodies in human serum thus far. To detect circulating anti-MUC1 antibodies, we established an indirect ELISA (I-ELISA) using a recombinant MUC1 protein containing six tandem repeat sequences of MUC1 after the antigenicity and specificity of the protein were confirmed. The I-ELISA had a sensitivity of 91.3% and a specificity of 94.1% when a competitive I-ELISA was used as a reference test. The results showed that more patients with benign breast tumors (P = 0.001) and breast cancer patients before primary treatment (P = 0.010) were found to have anti-MUC1 IgG than healthy women; anti-MUC1 IgG before primary treatment was found more than after primary treatment (P = 0.016) in breast cancer patients. Interestingly, the anti-MUC1 IgG serum level was reversely correlated to that of CA15-3 antigen in advanced-stage patients (r = -0.4294, P = 0.046). Our study has demonstrated the suitability of the established I-ELISA for detecting circulating anti-MUC1 antibodies in human serum. Furthermore, we found that circulating anti-MUC1 antibodies may still bind MUC1 shed into blood in stage IV breast cancer, which can support the use of MUC1-target immune therapy strategies.

MUC1-based recombinant Bacillus Calmette-Guerin vaccines as candidates for breast cancer immunotherapy

IMPORTANCE OF THE FIELD

The challenge in breast cancer vaccine development is to find the best combination of antigen, adjuvant and delivery system to produce a strong and long-lasting immune response. Mucin 1 (MUC1) is a potential candidate target for breast cancer immunotherapy. Bacillus Calmette-Guerin (BCG) is used widely in human vaccines. Furthermore, it can potentially offer unique advantages for developing a safe and effective multi-vaccine vehicle. Due to these properties, the development of MUC1 based recombinant BCG (rBCG) vaccines for breast cancer immunotherapy has gained great momentum in recent years.

AREAS COVERED IN THIS REVIEW

Our aim is to discuss the recent progress in MUC1-based breast cancer immunotherapy and to highlight the advantages of MUC1-based rBCG vaccines as the new breast cancer vaccines.

WHAT THE READER WILL GAIN

Several promising MUC1-based rBCG vaccines have been shown to induce MUC1-specific antitumor immune responses in pre-clinical studies. This review updates and evaluates this very important and rapidly developing field, and provides a critical perspective and information source for its potential clinical applications.

TAKE HOME MESSAGE

MUC1-based rBCG vaccines have been shown to elicit an effective anti-tumor immune response in vivo demonstrating its potential utility in breast cancer treatment.

Analysis of a cholera toxin B subunit (CTB) and human mucin 1 (MUC1) conjugate protein in a MUC1-tolerant mouse model

Since epithelial mucin 1 (MUC1) is associated with several adenocarcinomas at the mucosal sites, it is pertinent to test the efficacy of a mucosally targeted vaccine formulation. The B subunit of the Vibrio cholerae cholera toxin (CTB) has great potential to act as a mucosal carrier for subunit vaccines. In the present study we evaluated whether a MUC1 tandem repeat (TR) peptide chemically linked to CTB would break self-antigen tolerance in the transgenic MUC1-tolerant mouse model (MUC1.Tg) through oral or parenteral immunizations. We report that oral immunization with the CTB-MUC1 conjugate along with mucosal adjuvant, unmethylated CpG oligodeoxynucleotide (ODN) and interleukin-12 (IL-12) did not break self-antigen tolerance in MUC1.Tg mice, but induced a strong humoral response in wild-type C57BL/6 mice. However, self-antigen tolerance in the MUC1.Tg mouse model was broken after parenteral immunizations with different doses of the CTB-MUC1 conjugate protein and with the adjuvant CpG ODN co-delivered with CTB-MUC1. Importantly, mice immunized systemically with CpG ODN alone and with CTB-MUC1 exhibited decreased tumor burden when challenged with a mammary gland tumor cell line that expresses human MUC1.

Prognostic value of mucin 4 expression in colorectal adenocarcinomas

BACKGROUND

Mucin 4 (MUC4) is aberrantly expressed in colorectal adenocarcinomas (CRCs) but its prognostic value is unknown.

METHODS

Archival tissue specimens collected from 132 CRC patients who underwent surgical resection without presurgery or postsurgery therapy were evaluated for expression of MUC4 by using a mouse monoclonal antibody and horseradish peroxidase. MUC4 expression levels were correlated with clinicopathologic features and patient survival. Survival was estimated by both univariate Kaplan-Meier and multivariate Cox regression methods.

RESULTS

In both normal colonic epithelium and CRCs, MUC4 staining was localized primarily in the cytoplasm. The optimal immunostaining cutoff value (>or=75% positive cells and an immunostaining score>or=2.0), which was derived by using the bootstrap method, was used to categorize CRCs into groups of high expression (33 of 132 patients; 25%) or low expression (99 of 132 patients; 75%). Patients who had early stage tumors (stages I and II) with high MUC4 expression had a shorter disease-specific survival (log-rank; P=.007) than patients who had with low expression. Patients who had advanced-stage CRCs (stages III and IV) did not demonstrate such a difference (log-rank; P=.108). Multivariate regression models that were generated separately for patients with early stage and advanced-stage CRC confirmed that increased expression of MUC4 was an independent indicator of a poor prognosis only for patients who had early stage CRCs (hazard ratio, 3.77; 95% confidence interval, 1.46-9.73).

CONCLUSIONS

The current results indicated that increased MUC4 expression is a predictor of poor survival in CRC, specifically for patients who have early stage tumors.