The MUC13 cell surface mucin is highly expressed by human colorectal carcinomas

Deciphering cellular and molecular mechanism of MUC13 mucin involved in cancer cell plasticity and drug resistance

There has been a surge of interest in recent years in understanding the intricate mechanisms underlying cancer progression and treatment resistance. One molecule that has recently emerged in these mechanisms is MUC13 mucin, a transmembrane glycoprotein. Researchers have begun to unravel the molecular complexity of MUC13 and its impact on cancer biology. Studies have shown that MUC13 overexpression can disrupt normal cellular polarity, leading to the acquisition of malignant traits. Furthermore, MUC13 has been associated with increased cancer plasticity, allowing cells to undergo epithelial-mesenchymal transition (EMT) and metastasize. Notably, MUC13 has also been implicated in the development of chemoresistance, rendering cancer cells less responsive to traditional treatment options. Understanding the precise role of MUC13 in cellular plasticity, and chemoresistance could pave the way for the development of targeted therapies to combat cancer progression and enhance treatment efficacy.

MUC17 is an essential small intestinal glycocalyx component that is disrupted in Crohn's disease

Crohn's disease (CD) is the chronic inflammation of the ileum and colon triggered by bacteria, but insights into molecular perturbations at the bacteria-epithelium interface are limited. We report that membrane mucin MUC17 protects small intestinal enterocytes against commensal and pathogenic bacteria. In non-inflamed CD ileum, reduced MUC17 levels correlated with a compromised glycocalyx, allowing bacterial contact with enterocytes. Muc17 deletion in mice rendered the small intestine prone to atypical infection while maintaining resistance to colitis. The loss of Muc17 resulted in spontaneous deterioration of epithelial homeostasis and extra-intestinal translocation of bacteria. Finally, Muc17-deficient mice harbored specific small intestinal bacterial taxa observed in CD. Our findings highlight MUC17 as an essential line of defense in the small intestine with relevance for early epithelial defects in CD.

MUC13 drives cancer aggressiveness and metastasis through the YAP1-dependent pathway

Anchorage-independent survival after intravasation of cancer cells from the primary tumor site represents a critical step in metastasis. Here, we reveal new insights into how MUC13-mediated anoikis resistance, coupled with survival of colorectal tumor cells, leads to distant metastasis. We found that MUC13 targets a potent transcriptional coactivator, YAP1, and drives its nuclear translocation via forming a novel survival complex, which in turn augments the levels of pro-survival and metastasis-associated genes. High expression of MUC13 is correlated well with extensive macrometastasis of colon cancer cells with elevated nuclear YAP1 in physiologically relevant whole animal model systems. Interestingly, a positive correlation of MUC13 and YAP1 expression was observed in human colorectal cancer tissues. In brief, the results presented here broaden the significance of MCU13 in cancer metastasis via targeting YAP1 for the first time and provide new avenues for developing novel strategies for targeting cancer metastasis.

MUC13 Cell Surface Mucin Limits Salmonella Typhimurium Infection by Protecting the Mucosal Epithelial Barrier

BACKGROUND & AIMS

MUC13 cell surface mucin is highly expressed on the mucosal surface throughout the intestine, yet its role against bacterial infection is unknown. We investigated how MUC13 impacts Salmonella typhimurium (S Tm) infection and elucidated its mechanisms of action.

METHODS

Muc13-/- and wild-type littermate mice were gavaged with 2 isogenic strains of S Tm after pre-conditioning with streptomycin. We assessed clinical parameters, cecal histology, local and systemic bacterial load, and proinflammatory cytokines after infection. Cecal enteroids and epithelial cell lines were used to evaluate the mechanism of MUC13 activity after infection. The interaction between bacterial SiiE and MUC13 was assessed by using siiE-deficient Salmonella.

RESULTS

S Tm-infected Muc13-/- mice had increased disease activity, histologic damage, and higher local and systemic bacterial loads. Mechanistically, we found that S Tm binds to MUC13 through its giant SiiE adhesin and that MUC13 acts as a pathogen-binding decoy shed from the epithelial cell surface after pathogen engagement, limiting bacterial invasion. In addition, MUC13 reduces epithelial cell death and intestinal barrier breakdown by enhancing nuclear factor kappa B signaling during infection, independent of its decoy function.

CONCLUSIONS

We show for the first time that MUC13 plays a critical role in antimicrobial defense against pathogenic S Tm at the intestinal mucosal surface by both acting as a releasable decoy limiting bacterial invasion and reducing pathogen-induced cell death. This further implicates the cell surface mucin family in mucosal defense from bacterial infection.

The Mucin Family of Proteins: Candidates as Potential Biomarkers for Colon Cancer

Mucins (MUC1-MUC24) are a family of glycoproteins involved in cell signaling and barrier protection. They have been implicated in the progression of numerous malignancies including gastric, pancreatic, ovarian, breast, and lung cancer. Mucins have also been extensively studied with respect to colorectal cancer. They have been found to have diverse expression profiles amongst the normal colon, benign hyperplastic polyps, pre-malignant polyps, and colon cancers. Those expressed in the normal colon include MUC2, MUC3, MUC4, MUC11, MUC12, MUC13, MUC15 (at low levels), and MUC21. Whereas MUC5, MUC6, MUC16, and MUC20 are absent from the normal colon and are expressed in colorectal cancers. MUC1, MUC2, MUC4, MUC5AC, and MUC6 are currently the most widely covered in the literature regarding their role in the progression from normal colonic tissue to cancer.

MUC13-miRNA-4647 axis in colorectal cancer: Prospects to identifications of risk factors and clinical outcomes

MUC13, a transmembrane mucin glycoprotein, is overexpressed in colorectal cancer (CRC), however, its regulation and functions are not fully understood. It has been shown that MUC13 protects colonic epithelial cells from apoptosis. Therefore, studying MUC13 and MUC13-regulated pathways may reveal promising therapeutic approaches for CRC treatment. Growing evidence suggests that microRNAs (miRs) are involved in the development and progression of CRC. In the present study, the MUC13-miR-4647 axis was addressed in association with survival of patients. miR-4647 is predicted in silico to bind to the MUC13 gene and was analyzed by RT-qPCR in 187 tumors and their adjacent non-malignant mucosa of patients with CRC. The impact of previously mentioned genes on survival and migration abilities of cancer cells was validated in vitro. Significantly upregulated MUC13 (P=0.02) in was observed tumor tissues compared with non-malignant adjacent mucosa, while miR-4647 (P=0.05) showed an opposite trend. Higher expression levels of MUC13 (log-rank P=0.05) were associated with worse patient's survival. The ectopic overexpression of studied miR resulted in decreased migratory abilities and worse survival of cells. Attenuated MUC13 expression levels confirmed the suppression of colony forming of CRC cells. In summary, the present data suggested the essential role of MUC13-miR-4647 in patients' survival, and this axis may serve as a novel therapeutic target. It is anticipated MUC13 may hold significant potential in the screening, diagnosis and treatment of CRC.

Clinical diagnosis and treatment strategies for sarcomatoid intrahepatic cholangiocarcinoma

Sarcomatoid intrahepatic cholangiocarcinoma (SiCCA) is a malignant tumor composed of mixed epithelial cells and mesenchymal cells derived from malignant bile duct cells. SiCCA has a low incidence and has no specific clinical manifestations and serological and imaging examinations. The diagnosis of SiCCA relies on histopathology and immunohistochemistry. The very high malignancy of SiCCA makes it prone to liver and other organ metastases. SiCCA has a poor prognosis because it has a low surgical resection rate, is easy to relapse shortly after surgery, and has no effective prevention and treatment measures. Comprehensive analysis integrating imaging, serum tumor markers, and histopathological examination technology is an important measure to improve the diagnosis of SiCCA and reduce the misdiagnosis rate. Early diagnosis, surgical treatment, and comprehensive postoperative treatment based on chemotherapy are the keys to improving the survival and prognosis of patients with SiCCA.

Early-Stage Loss of GALNT6 Predicts Poor Clinical Outcome in Colorectal Cancer

Colorectal adenocarcinomas arise from luminal lining epithelium of the colorectal tract which is covered with highly glycosylated mucins. Mucin O-glycosylation is initiated by a family of polypeptide N-acteylgalactosaminyltransferases (GALNTs). This study examined GALNT6 protein expression in 679 colorectal tumors, including 574 early-stage and 105 late-stage cancers. GALNT6 expression in cancer tissue varied widely between patients ranging from high levels to complete loss. Loss of GALNT6 occurred in 9.9% of early-stage and 15.2% of late-stage cancers and was more prevalent in grade 3 or MSI subtype tumors. Survival analyses revealed that loss of GALNT6 expression is prognostic of reduced overall survival, and univariate and multivariate analyses demonstrated that loss of GALNT6 is an independent risk variable. We also analyzed 508-case TCGA and 63-case CPTAC colorectal cancer cohorts for all members of the GALNT enzyme family, the mucin family, as well as KRAS and BRAF mutations. GLANT6 mRNA expression showed no strong correlation with other GALNTs or mucins but was significantly higher in KRAS mutated or BRAF wild-type early-stage cancers. Using large cohorts of patients and different approaches, this study shows that loss of GALNT6 enzyme in early-stage colorectal cancer predicts poor clinical outcomes.

Quercetin Inhibits Tumorigenesis of Colorectal Cancer Through Downregulation of hsa_circ_0006990

Quercetin can significantly inhibit the progression of colorectal cancer (CRC). However, its specific mechanism remains largely unclear. In this study, we aimed to explore the correlation among quercetin, tumour-associated macrophages (TAMs) and circular RNAs (circRNAs) in the progression of CRC and to present a novel strategy for the treatment of CRC. In this study, we revealed that quercetin could suppress the autophagy of M2-TAMs and induced their differentiation into M1-TAMs, by which quercetin significantly reversed the inhibition of M2-TAMS on CRC cell apoptosis and the promotion of M2-TAMS on CRC cell proliferation. Moreover, quercetin could promote the expression of downregulated hsa_circ_0006990 in CRC cells co-cultured with M2-TAMs, and the overexpression of hsa_circ_0006990 significantly reversed the anti-tumour effect of quercetin on CRC. Furthermore, we found quercetin can notably suppress the progression of CRC via mediation of the hsa_circ_0006990/miR-132-3p/MUC13 axis. In conclusion, our results suggested that quercetin inhibits the tumorigenesis of CRC via inhibiting the polarisation of M2 macrophages and downregulating hsa_circ_0006990. Our study provides useful insights for those exploring new methods of treating CRC.

Long noncoding RNA BBOX1-AS1 promotes the progression of gastric cancer by regulating the miR-361-3p/Mucin 13 signaling axis

Gastric cancer (GC) places a heavy burden on global health, and the information on the molecular mechanism of the progression of GC is still inadequate. Long noncoding RNA (LncRNA) has been confirmed to be widely involved in regulating the progression of GC. Our aim in this study was to explore the role and potential regulatory mechanism of lncRNA BBOX1-AS1 in GC. The expression levels of BBOX1-AS1, miR-361-3p, and MUC13 in GC tissues and cells were evaluated using quantitative real-time polymerase chain reaction and western blotting. The silencer of BBOX1 antisense RNA 1 (BBOX1-AS1) and mucin 13 (MUC13), the mimics and inhibitor of miR-361-3p, and their negative controls were used to alter the expression of these genes. Luciferase reporter, pull-down, and RNA immunoprecipitation assays were performed to verify the correlation between miR-361-3p, BBOX1-AS1, and MUC13. GC cell proliferation, invasion, and apoptosis were detected by cell counting kit-8, transwell, and flow cytometry assays, respectively. An in vivo functional experiment was performed to assess the effect of BBOX1-AS1 on GC. The results showed that BBOX1-AS1 was significantly upregulated in GC tissues. Silencing of BBOX1-AS1 inhibited GC cell proliferation and invasion and inhibited tumor growth in vivo, whereas it promoted apoptosis. MiR-361-3p was significantly downregulated in GC and counteracted the inhibitory effects of BBOX1-AS1 on GC progression. MUC13, which is targeted by miR-361-3p, is significantly upregulated in GC. MUC13 silencing inhibited GC progression was aborgated by miR-361-3p inhibitor. Collectively, BBOX1-AS1 silencing inhibits GC progression by regulating the miR-361-3p/MUC13 axis, providing a potential therapeutic biomarker for GC.

Mucin1 and Mucin16: Therapeutic Targets for Cancer Therapy

The mucin (MUC) family is a group of highly glycosylated macromolecules that are abundantly expressed in mammalian epithelial cells. MUC proteins contribute to the formation of the mucus barrier and thus have protective functions against infection. Interestingly, some MUC proteins are aberrantly expressed in cancer cells and are involved in cancer development and progression, including cell growth, proliferation, the inhibition of apoptosis, chemoresistance, metabolic reprogramming, and immune evasion. With their unique biological and structural features, MUC proteins have been considered promising therapeutic targets and also biomarkers for human cancer. In this review, we discuss the biological roles of the transmembrane mucins MUC1 and MUC16 in the context of hallmarks of cancer and current efforts to develop MUC1- and MUC16-targeted therapies.

Ingested Engineered Nanomaterials Affect the Expression of Mucin Genes-An In Vitro-In Vivo Comparison

The increasing use of engineered nanomaterials (ENM) in food has fueled the development of intestinal in vitro models for toxicity testing. However, ENM effects on intestinal mucus have barely been addressed, although its crucial role for intestinal health is evident. We investigated the effects of ENM on mucin expression and aimed to evaluate the suitability of four in vitro models of increasing complexity compared to a mouse model exposed through feed pellets. We assessed the gene expression of the mucins MUC1, MUC2, MUC5AC, MUC13 and MUC20 and the chemokine interleukin-8 in pre-confluent and confluent HT29-MTX-E12 cells, in stable and inflamed triple cultures of Caco-2, HT29-MTX-E12 and THP-1 cells, and in the ileum of mice following exposure to TiO₂, Ag, CeO₂ or SiO₂. All ENM had shared and specific effects. CeO₂ downregulated MUC1 in confluent E12 cells and in mice. Ag induced downregulation of Muc2 in mice. Overall, the in vivo data were consistent with the findings in the stable triple cultures and the confluent HT29-MTX-E12 cells but not in pre-confluent cells, indicating the higher relevance of advanced models for hazard assessment. The effects on MUC1 and MUC2 suggest that specific ENM may lead to an elevated susceptibility towards intestinal infections and inflammations.

The Roles of Transmembrane Mucins Located on Chromosome 7q22.1 in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common types of cancers. It is associated with a poor prognosis and high mortality. The role of mucins (MUCs) in colon tumorigenesis is unclear, but it might be significant in the progression of malignancy. Some mucins, such as MUC1 and MUC13, act as oncogenes, whereas others, such as MUC2 and MUC6, are tumor suppressors. However, there are still mucins with unidentified roles in CRC. In this review, we discuss the reported roles of mucins in CRC. Moreover, we review the capability of the mucin family to serve as a sensitive and specific histopathological marker for the early diagnosis of CRC. Lastly, the role of mucin genes clustered on chromosome 7q22 in CRC and other cancers is also discussed.

Development of Human Lung Induction Models for Air Pollutants' Toxicity Assessment

There is an urgent need for reliable and effective models to study air pollution health effects on human lungs. Here, we report the utilization of human pluripotent stem cell (hPSC) induction models for human lung progenitor cells (hLPs) and alveolar type 2 epithelial cell-like cells (ATLs) for the toxicity assessment of benzo(a)pyrene, nano-carbon black, and nano-SiO₂, as common air pollutants. We induced hPSCs to generate ATLs, which recapitulated key features of human lung type 2 alveolar epithelial cells, and tested the induction models for cellular uptake of nanoparticles and toxicity evaluations. Our findings reveal internalization of nano-carbon black, dose-dependent uptake of nano-SiO₂, and interference with surfactant secretion in ATLs exposed to benzo(a)pyrene/nano-SiO₂. Thus, hLP and ATL induction models could facilitate the evaluation of environmental pollutants potentially affecting the lungs. In conclusion, this is one of the first studies that managed to adopt hPSC pulmonary induction models in toxicology studies.

IL-22 promotes the formation of a MUC17 glycocalyx barrier in the postnatal small intestine during weaning

The intestine is under constant exposure to chemicals, antigens, and microorganisms from the external environment. Apical aspects of transporting epithelial cells (enterocytes) form a brush-border membrane (BBM), shaped by packed microvilli coated with a dense glycocalyx. We present evidence showing that the glycocalyx forms an epithelial barrier that prevents exogenous molecules and live bacteria from gaining access to BBM. We use a multi-omics approach to investigate the function and regulation of membrane mucins exposed on the BBM during postnatal development of the mouse small intestine. Muc17 is identified as a major membrane mucin in the glycocalyx that is specifically upregulated by IL-22 as part of an epithelial defense repertoire during weaning. High levels of IL-22 at time of weaning reprogram neonatal postmitotic progenitor enterocytes to differentiate into Muc17-expressing enterocytes, as found in the adult intestine during homeostasis. Our findings propose a role for Muc17 in epithelial barrier function in the small intestine.

Proteomic Analysis of the Air-Way Fluid in Lung Cancer. Detection of Periostin in Bronchoalveolar Lavage (BAL)

Background: Bronchoalveolar lavage (BAL) is a specific type of air-way fluid. It is a commonly used clinical specimen for the diagnosis of benign diseases and cancers of the lung. Although previous studies have identified several disease-associated proteins in the BAL, the potential utility of BAL in lung cancer is still not well-studied. Based upon the fact that the majority of secreted proteins are glycoproteins, we have profiled N-glycoproteins in BAL collected from lung cancers, and investigated the expression of glycoproteins such as the matrix N-glycoprotein, periostin, in lung cancers. Methods: BAL specimens (n = 16) were collected from lung cancer patients, and analyzed using mass spectrometry-based quantitative N-glycoproteomic technique. Additional BAL specimens (n = 39) were independently collected to further evaluate the expression of periostin by using an enzyme-linked immunosorbent assay (ELISA). Results: A total of 462 glycoproteins were identified in BAL samples using N-glycoproteomic technique, including 290 in lung adenocarcinoma (ADC, n = 5), 376 in squamous cell carcinoma (SQCC, n = 4), 309 in small cell lung carcinoma (SCLC, n = 4), and 316 in benign lung disease (n = 3). The expressions of several glycoproteins were elevated, including 8 in ADC, 12 in SQCC, and 17 in SCLC, compared to benign BALs. The expression of periostin was detected in all subtypes of lung cancers. To further investigate the expression of periostin, an ELISA assay was performed using additional independently collected BALs (n = 39) The normalized levels of periostin in benign disease, ADC, SQCC, and SCLC were 255 ± 104 (mean ± SE) and 4,002 ± 2,181, 3,496 ± 1,765, and 1,772 ± 1,119 ng/mg of total BAL proteins. Conclusion: Our findings demonstrate that proteomic analysis of BAL can be used for the study of cancer-associated extracellular proteins in air-way fluid from lung cancer patients.

MUC13 promotes the development of colitis-associated colorectal tumors via β-catenin activity

Many adenocarcinomas, including colorectal cancer (CRC), overexpress the MUC13 cell surface mucin, but the functional significance and mechanisms are unknown. Here, we report the roles of MUC13 in colonic tumorigenesis and tumor progression. High-MUC13 expression is associated with poor survival in two independent patient cohorts. In a comprehensive series of in vivo experiments, we identified a critical role for MUC13 in the development of this malignancy, by promoting survival and proliferation of tumor-initiating cells and driving an immunosuppressive environment that protects tumors from checkpoint inhibitor immunotherapy. In Muc13-deficient mice, fewer tumors are generated after exposure to carcinogens and inflammation, they have markedly reduced β-catenin signaling, have more tumor-infiltrating CD103⁺ dendritic cells and CD8⁺ T lymphocytes, fewer myeloid-derived suppressor cells, and are rendered sensitive to checkpoint inhibitor immunotherapy (anti-PD-L1). Mechanistically, we show that MUC13 protects β-catenin from degradation, by interacting with GSK-3β, which increases β-catenin nuclear translocation and promotes its signaling, thereby driving cancer initiation, progression, invasion, and immune suppression. Therefore, MUC13 is a potential marker of poor prognosis in colorectal cancer, and inhibiting MUC13 may be useful in the treatment of colitis-associated cancer and sensitizing tumors to immunotherapy.

Loss of Bcl-G, a Bcl-2 family member, augments the development of inflammation-associated colorectal cancer

Gastrointestinal epithelial cells provide a selective barrier that segregates the host immune system from luminal microorganisms, thereby contributing directly to the regulation of homeostasis. We have shown that from early embryonic development Bcl-G, a Bcl-2 protein family member with unknown function, was highly expressed in gastrointestinal epithelial cells. While Bcl-G was dispensable for normal growth and development in mice, the loss of Bcl-G resulted in accelerated progression of colitis-associated cancer. A label-free quantitative proteomics approach revealed that Bcl-G may contribute to the stability of a mucin network, which when disrupted, is linked to colon tumorigenesis. Consistent with this, we observed a significant reduction in Bcl-G expression in human colorectal tumors. Our study identifies an unappreciated role for Bcl-G in colon cancer.

Resistance to ETEC F4/F18-mediated piglet diarrhoea: opening the gene black box

Diarrhoea, a significant problem in pig rearing industry affecting pre- and post-weaning piglets is caused by enterotoxigenic Escherichia coli (ETEC). The ETEC are classified as per the fimbriae types which are responsible for bacterial attachment with enterocytes and release of toxins causing diarrhoea. However, genetic difference exists for susceptibility to ETEC infection in piglets. The different phenotypes found in pigs determine their (pigs') susceptibility or resistance towards fimbrial subtypes/variants (F4ab, F4ac, F4ad and F18). Specific receptors are present on intestinal epithelium for attachment of these fimbriae, which do not express to same level in all animals. This differential expression is genetically determined and thus their genetic causes (may be putative candidate gene or mutations) render some animals resistant or susceptible to one or more fimbrial subtypes. Genetic linkage studies have revealed the mapping location of the receptor loci for the two most frequent variants F4ab and F4ac to SSC13q41 (i.e. q arm of 13th chromosome of Sus scrofa). Some SNPs have been identified in mucin gene family, transferring receptor gene, fucosyltransferase 1 gene and swine leucocyte antigen locus that are proposed to be linked mutations for resistance/susceptibility towards ETEC diarrhoea. However, owing to the variety of fimbrial types and subtypes, it would be difficult to identify a single causative mutation and the candidate loci may involve more number of genes/regions. In this review, we focus on the genetic mutations in genes involved in imparting resistance/susceptibility to F4 or F18 ETEC diarrhoea and possibilities to use them as marker for selection against susceptible animals.

Single-cell genetic analysis of clonal dynamics in colorectal adenomas indicates CDX2 gain as a predictor of recurrence

Colorectal adenomas are common precancerous lesions with the potential for malignant transformation to colorectal adenocarcinoma. Endoscopic polypectomy provides an opportunity for cancer prevention; however, recurrence rates are high. We collected formalin-fixed paraffin-embedded tissue of 15 primary adenomas with recurrence, 15 adenomas without recurrence, and 14 matched pair samples (primary adenoma and the corresponding recurrent adenoma). The samples were analysed by array-comparative genomic hybridisation (aCGH) and single-cell multiplex interphase fluorescence in situ hybridisation (miFISH) to understand clonal evolution, to examine the dynamics of copy number alterations (CNAs) and to identify molecular markers for recurrence prediction. The miFISH probe panel consisted of 14 colorectal carcinogenesis-relevant genes (COX2, PIK3CA, APC, CLIC1, EGFR, MYC, CCND1, CDX2, CDH1, TP53, HER2, SMAD7, SMAD4 and ZNF217), and a centromere probe (CEP10). The aCGH analysis confirmed the genetic landscape typical for colorectal tumorigenesis, that is, CNAs of chromosomes 7, 13q, 18 and 20q. Focal aberrations (≤10 Mbp) were mapped to chromosome bands 6p22.1-p21.33 (33.3%), 7q22.1 (31.4%) and 16q21 (29.4%). MiFISH detected gains of EGFR (23.6%), CDX2 (21.8%) and ZNF217 (18.2%). Most adenomas exhibited a major clone population which was accompanied by multiple smaller clone populations. Gains of CDX2 were exclusively seen in primary adenomas with recurrence (25%) compared to primary adenomas without recurrence (0%). Generation of phylogenetic trees for matched pair samples revealed four distinct patterns of clonal dynamics. In conclusion, adenoma development and recurrence are complex genetic processes driven by multiple CNAs whose evaluations by miFISH, with emphasis on CDX2, might serve as a predictor of recurrence.

Exploring the potential of mucin 13 (MUC13) as a biomarker for carcinomas and other diseases

BACKGROUND

Mucin 13 (MUC13) is a cell surface glycoprotein aberrantly expressed in a variety of epithelial carcinomas. Thus far, the role of MUC13 in various diseases remains elusive. To the best of our knowledge, this is the first study to examine the potential of MUC13 as a serum biomarker in a variety of carcinomas and other conditions.

METHODS

We developed a recombinant MUC13 protein, mouse monoclonal antibodies and enzyme immunoassay (ELISA) for MUC13. We used this assay to measure MUC13 levels in the supernatants of cancer cell lines and a large cohort of serum samples from healthy and diseased individuals.

RESULTS

MUC13 is secreted from cancer cell lines, with highest levels found in ovarian cancer cell lines. MUC13 levels in human sera were significantly increased in patients with renal failure and 20%-30% of patients with ovarian, liver, lung and other cancers. MUC13 was also elevated in 70% of patients with active cutaneous melanoma, but not uveal melanoma. Furthermore, we identified significant MUC13 elevations in the serum of patients with vasculitis (ANCA-positive) autoantibodies, but not in those with inflammatory bowel disease.

CONCLUSIONS

Serum MUC13 is frequently elevated not only in a variety of malignant cases but also in some benign pathologies, thus appearing to be a non-specific disease biomarker. Nonetheless, serum MUC13 is clearly highly elevated in some carcinoma patients, and its relationship with tumor progression in this context warrant further research. Future studies that examine the correlation between serum MUC13 levels to stage of cancer could elucidate prognostic potential.

The Interaction of the Gut Microbiota with the Mucus Barrier in Health and Disease in Human

Glycoproteins are major players in the mucus protective barrier in the gastrointestinal and other mucosal surfaces. In particular the mucus glycoproteins, or mucins, are responsible for the protective gel barrier. They are characterized by their high carbohydrate content, present in their variable number, tandem repeat domains. Throughout evolution the mucins have been maintained as integral components of the mucosal barrier, emphasizing their essential biological status. The glycosylation of the mucins is achieved through a series of biosynthetic pathways processes, which generate the wide range of glycans found in these molecules. Thus mucins are decorated with molecules having information in the form of a glycocode. The enteric microbiota interacts with the mucosal mucus barrier in a variety of ways in order to fulfill its many normal processes. How bacteria read the glycocode and link to normal and pathological processes is outlined in the review.

Clinicopathological and prognostic significance of MUC13 and AGR2 expression in intraductal papillary mucinous neoplasms of the pancreas

BACKGROUND

Intraductal papillary mucinous neoplasm (IPMN) of the pancreas is a primary pancreatic ductal epithelial neoplasm with the potential to develop into an invasive adenocarcinoma. This study aimed to investigate the clinicopathologic and prognostic significance of four potential biomarkers for the preoperative evaluation of patients with IPMN.

MATERIALS AND METHODS

Clinicopathologic materials from 104 patients with IPMN who underwent surgical resection at Jichi Medical University Hospital were analyzed. IPMNs (110 lesions in total) were histologically classified into low-grade IPMN (Group 1; n = 68), high-grade IPMN (Group 2; n = 16), or IPMN with an associated invasive carcinoma (Group 3; n = 26). We evaluated the immunohistochemical expression of MUC13, AGR2, FUT8, and FXYD3, which were previously reported to be overexpressed in pancreatic ductal adenocarcinoma.

RESULTS

The expression of MUC13 was more common in Group 3 compared with groups 1 and 2 (p < 0.001) and was associated with poor prognosis (p = 0.004). The expression of MUC13 was not associated with age, sex, tumor location, histological subtype, lymphatic or vascular invasion, or neural invasion. In most cases of IPMN, the loss of expression of AGR2 appeared to show an association with tumor recurrence and poorly differentiated histology of invasive carcinoma; however, this association was not statistically significant. The expressions of FUT8 and FXYD3were not associated with the clinicopathological features of IPMNs.

CONCLUSIONS

The results suggest that MUC13 overexpression and loss of expression of AGR2 may predict the progression of IPMN and an unfavorable prognosis in patients with IPMN.

High expression of Mucin13 associates with grimmer postoperative prognosis of patients with non-metastatic clear-cell renal cell carcinoma

Background

Mucin13 (MUC13) is a transmembrane glycoprotein that is aberrantly expressed in ovarian and gastro-intestinal tumors, but its role in renal cell carcinoma remains elusive. The purpose of this study is to evaluate the prognostic value of MUC13 expression in patients with non-metastatic clear cell renal cell carcinoma (ccRCC) after surgical resection.

Results

MUC13 high expression was associated with high Fuhrman grade (p < 0.001), high SSIGN score (p = 0.011), early recurrence (p < 0.001) and poor survival (p < 0.001). Multivariate Cox regression analysis identified MUC13 expression as an independent prognostic factor for RFS and OS of ccRCC patients. A nomogram integrating MUC13 expression and other independent prognosticators was established to predict RFS and OS of ccRCC patients. Optimal agreement was shown between the predictions and observations in calibration curves.

Matrials and methods

This study enrolled 410 postoperative non-metastatic ccRCC patients at a single institution. Clinicopathologic variables, recurrence-free survival (RFS), and overall survival (OS) were recorded. MUC13 expression was detected by immunohistochemical staining in tumor specimens. Association of MUC13 expression with clinicopathological factors was explored. Kaplan-Meier analysis was performed to compare survival curves. Univariate and multivariate Cox regression models were used to analyze the impact of prognostic factors on RFS and OS. A prognostic nomogram was constructed based on the independent prognostic factors identified by multivariate analysis.

Conclusions

MUC13 high expression is a novel independent adverse prognostic factor of clinical outcome in non-metastatic ccRCC patients after surgery.

Mucins: Structural diversity, biosynthesis, its role in pathogenesis and as possible therapeutic targets

Mucins are the main structural components of mucus that create a selective protective barrier for epithelial surface and also execute wide range of other physiological functions. Mucins can be classified into two types, namely secreted mucins and membrane bounded mucins. Alterations in mucin expression or glycosylation and mislocalization have been seen in various types of pathological conditions such as cancers, inflammatory bowel disease and ocular disease, which highlight the importance of mucin in maintaining homeostasis. Hence mucins can be used as attractive target for therapeutic intervention. In this review, we discuss in detail about the structural diversity of mucins; their biosynthesis; its role in pathogenesis; regulation and as possible therapeutic targets.

A mutational comparison of adult and adolescent and young adult (AYA) colon cancer

BACKGROUND

It is possible that the relative lack of progress in treatment outcomes among adolescent and young adult (AYA) patients with cancer is caused by a difference in disease biology compared with the corresponding diseases in younger and older individuals. There is evidence that colon cancer is more aggressive and has a poorer prognosis in AYA patients than in older adult patients.

METHODS

To further understand the molecular basis for this difference, whole-exome sequencing was conducted on a cohort of 30 adult, 30 AYA, and 2 pediatric colon cancers.

RESULTS

A statistically significant difference in mutational frequency was observed between AYA and adult samples in 43 genes, including ROBO1, MYC binding protein 2 (MYCBP2), breast cancer 2 (early onset) (BRCA2), MAP3K3, MCPH1, RASGRP3, PTCH1, RAD9B, CTNND1, ATM, NF1; KIT, PTEN, and FBXW7. Many of these mutations were nonsynonymous, missense, stop-gain, or frameshift mutations that were damaging. Next, RNA sequencing was performed on a subset of the samples to confirm the mutations identified by exome sequencing. This confirmation study verified the presence of a significantly greater frequency of damaging mutations in AYA compared with adult colon cancers for 5 of the 43 genes (MYCBP2, BRCA2, PHLPP1, TOPORS, and ATR).

CONCLUSIONS

The current results provide the rationale for a more comprehensive study with a larger sample set and experimental validation of the functional impact of the identified variants along with their contribution to the biologic and clinical characteristics of AYA colon cancer. Cancer 2018;124:1070-82. © 2017 American Cancer Society.

Colonic transcriptional response to 1α,25(OH)2 vitamin D3 in African- and European-Americans

Colorectal cancer (CRC) is a significant health burden especially among African Americans (AA). Epidemiological studies have correlated low serum vitamin D with CRC risk, and, while hypovitaminosis D is more common and more severe in AA, the mechanisms by which vitamin D modulates CRC risk and how these differ by race are not well understood. Active vitamin D (1α,25(OH)₂D₃) has chemoprotective effects primarily through transcriptional regulation of target genes in the colon. We hypothesized that transcriptional response to 1α,25(OH)₂D₃ differs between AA and European Americans (EA) irrespective of serum vitamin D and that regulatory variants could impact transcriptional response. We treated ex vivo colon cultures from 34 healthy subjects (16 AA and 18 EA) with 0.1μM 1α,25(OH)₂D₃ or vehicle control for 6h and performed genome-wide transcriptional profiling. We found 8 genes with significant differences in transcriptional response to 1α,25(OH)₂D₃ between AA and EA with definitive replication of inter-ethnic differences for uridine phosphorylase 1 (UPP1) and zinc finger-SWIM containing 4 (ZSWIM4). We performed expression quantitative trait loci (eQTL) mapping and identified response cis-eQTLs for ZSWIM4 as well as for histone deacetylase 3 (HDAC3), the latter of which showed a trend toward significant inter-ethnic differences in transcriptional response. Allele frequency differences of eQTLs for ZSWIM4 and HDAC3 accounted for observed transcriptional differences between populations. Taken together, our results demonstrate that transcriptional response to 1α,25(OH)₂D₃ differs between AA and EA independent of serum 25(OH)D levels. We provide evidence in support of a genetic regulatory mechanism underlying transcriptional differences between populations for ZSWIM4 and HDAC3. Further work is needed to elucidate how response eQTLs modify vitamin D response and whether genotype and/or transcriptional response correlate with chemopreventive effects. Relevant biomarkers, such as tissue-specific 1α,25(OH)₂D₃ transcriptional response, could identify individuals likely to benefit from vitamin D for CRC prevention as well as elucidate basic mechanisms underlying CRC disparities.

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.

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.

Mucin-Microbiota Interaction During Postnatal Maturation of the Intestinal Ecosystem: Clinical Implications

The mucus layer and gut microbiota interplay contributes to host homeostasis. The mucus layer serves as a scaffold and a carbon source for gut microorganisms; conversely, gut microorganisms, including mucin degraders, influence mucin gene expression, glycosylation, and secretion. Conjointly they shield the epithelium from luminal pathogens, antigens, and toxins. Importantly, the mucus layer and gut microbiota are established in parallel during early postnatal life. During this period, the development of gut microbiota and mucus layer is coupled with that of the immune system. Developmental changes of different mucin types can impact the age-dependent patterns of intestinal infection in terms of incidence and severity. Altered mucus layer, dysbiotic microbiota, and abnormal mucus-gut microbiota interaction have the potential for inducing systemic effects, and accompany several intestinal diseases such as inflammatory bowel disease, colorectal cancer, and radiation-induced mucositis. Early life provides a pivotal window of opportunity to favorably modulate the mucus-microbiota interaction. The support of a health-compatible mucin-microbiota maturation in early life is paramount for long-term health and serves as an important opportunity for clinical intervention.

Dose-dependent benefits of quercetin on tumorigenesis in the C3(1)/SV40Tag transgenic mouse model of breast cancer

Breast cancer is the leading cause of cancer related death in women. Quercetin is a flavonol shown to have anti-carcinogenic actions. However, few studies have investigated the dose-dependent effects of quercetin on tumorigenesis and none have used the C3(1)/SV40 Tag breast cancer mouse model. At 4 weeks of age female C3(1)/SV40 Tag mice were randomized to one of four dietary treatments (n = 15-16/group): control (no quercetin), low-dose quercetin (0.02% diet), moderate-dose quercetin (0.2% diet), or high-dose quercetin (2% diet). Tumor number and volume was assessed twice a week and at sacrifice (20 wks). Results showed an inverted 'U' dose-dependent effect of dietary quercetin on tumor number and volume; at sacrifice the moderate dose was most efficacious and reduced tumor number 20% and tumor volume 78% compared to control mice (C3-Con: 9.0 ± 0.9; C3-0.2%: 7.3 ± 0.9) and (C3-Con: 2061.8 ± 977.0 mm(3); and C3-0.2%: 462.9 ± 75.9 mm(3)). Tumor volume at sacrifice was also reduced by the moderate dose compared to the high and low doses (C3-2%: 1163.2 ± 305.9 mm(3); C3-0.02%: 1401.5 ± 555.6 mm(3)), as was tumor number (C3-2%: 10.7 ± 1.3 mm(3); C3-0.02%: 8.1 ± 1.1 mm(3)). Gene expression microarray analysis performed on mammary glands from C3-Con and C3-0.2% mice determined that 31 genes were down-regulated and 9 genes were up-regulated more than 2-fold (P < 0.05) by quercetin treatment. We report the novel finding that there is a distinct dose-dependent effect of quercetin on tumor number and volume in a transgenic mouse model of human breast cancer, which is associated with a specific gene expression signature related to quercetin treatment.

A newly developed anti-Mucin 13 monoclonal antibody targets pancreatic ductal adenocarcinoma cells

Pancreatic cancer is one of the most severe forms of malignancy. Patients with unresectable or metastatic pancreatic cancer usually receive chemotherapy that causes various adverse effects. Antibody-drug conjugates (ADCs), drugs developed by conjugating an anticancer agent to a monoclonal antibody (mAb), can alleviate the side effects of chemotherapy because ADCs selectively bind to cancer cells expressing a particular antigen. We recently developed the recombinant protein DT3C comprising diphtheria toxin (DT) lacking the receptor-binding domain but containing the C1, C2, and C3 domains of Streptococcus protein G (3C). The mAb-DT3C conjugates can be used to select mAbs that are internalized by cells, because the conjugates decrease cell viability only when they are internalized by cells through Ab-antigen reactions. We developed a new mAb to be internalized by TCC-PAN2 cells, a pancreatic carcinoma cell line. The mAb, designated TCC56, recognized Mucin 13 (MUC13), while TCC56‑DT3C conjugates induced cell death in TCC-PAN2 cells expressing MUC13. We found that MUC13 was expressed, at least partially, in all 40 pancreatic ductal carcinoma tissues and adjacent non-cancerous tissues analyzed. The expression levels of MUC13 in pancreatic cancer tissues were greater than those in normal tissues. Our findings suggest that MUC13 can be a target molecule for pancreatic cancer treatment. ADCs, including mAb TCC56, could be promising anticancer agents to alleviate the adverse effects of chemotherapy.

Functions and regulation of MUC13 mucin in colon cancer cells

BACKGROUND

MUC13 is overexpressed and aberrantly localized in colon cancer tissue; however, the specific functions and regulation of MUC13 expression are unknown.

METHODS

Stable cell lines with either overexpressed or suppressed MUC13 levels were analyzed to determine cell growth, colony formation, cell migration, and cell invasion assays. The molecular mechanisms involved in MUC13 regulation were elucidated via chromatin immunoprecipitation (ChIP) and analysis of interleukin 6 (IL6) treatments. Colon cancer tissues were analyzed by immunohistochemistry (IHC) for the protein levels of MUC13 and P-STAT5 in colon cancer cells.

RESULTS

Overexpression of MUC13 increased cell growth, colony formation, cell migration, and invasion. In concordance, MUC13 silencing decreased these tumorigenic features. Overexpression of MUC13 also modulated various cancer-associated proteins, including telomerase reverse transcriptase, sonic hedgehog, B cell lymphoma murine like site 1, and GATA like transcription factor 1. Additionally, MUC13-overexpressing cells showed increased HER2 and P-ERK expression. ChIP analysis revealed binding of STAT5 to the predicted MUC13 promoter. IL6 treatment of colon cancer cells increased the expression of MUC13 via activation of the JAK2/STAT5 signaling pathway. Suppression of JAK2 and STAT5 signaling by chemical inhibitors abolished IL6-induced MUC13 expression. IHC analysis showed increased expression of both P-STAT5 and MUC13 in colon cancer as compared to adjacent normal tissue.

CONCLUSIONS

The results of this study, for the first time, suggest functional roles of MUC13 in colon cancer progression and provide information regarding the regulation of MUC13 expression via JAK2/STAT5 which may reveal promising therapeutic approaches for colon cancer treatment.

Overexpression of mucin 13 due to promoter methylation promotes aggressive behavior in ovarian cancer cells

PURPOSE

Recent discoveries suggest that aberrant DNA methylation provides cancer cells with advanced metastatic properties. However, the precise regulatory mechanisms controlling metastasis genes and their role in metastatic transformation are largely unknown. To address epigenetically-regulated gene products involved in ovarian cancer metastasis, we examined the mechanisms regulating mucin 13 (MUC13) expression and its influence on aggressive behaviors of ovarian malignancies.

MATERIALS AND METHODS

We injected SK-OV-3 ovarian cancer cells peritoneally into nude mice to mimic human ovarian tumor metastasis. Overexpression of MUC13 mRNA was detected in metastatic implants from the xenografts by expression microarray analysis and quantitative reverse-transcription polymerase chain reaction (qRT-PCR). The DNA methylation status within the MUC13 promoter region was determined using bisulfite sequencing PCR and quantitative methylation-specific PCR. We evaluated the effects of exogenous MUC13 on cell invasion and migration using in vitro transwell assays.

RESULTS

MUC13 mRNA expression was up-regulated, and methylation of specific CpG sites within the promoter was reduced in the metastatic implants relative to those in wild-type SK-OV-3 cells. Addition of a DNA methyltransferase inhibitor to SK-OV-3 cells induced MUC13 expression, thereby implying epigenetic regulation of MUC13 by promoter methylation. MUC13 overexpression increased migration and invasiveness, compared to control cells, suggesting aberrant up-regulation of MUC13 is strongly associated with progression of aggressive behaviors in ovarian cancer.

CONCLUSION

We provide novel evidence for epigenetic regulation of MUC13 in ovarian cancer. We suggest that the DNA methylation status within the MUC13 promoter region may be a potential biomarker of aggressive behavior in ovarian cancer.

Mucin 15 is lost but mucin 13 remains in uterine luminal epithelial cells and the blastocyst at the time of implantation in the rat

The glycocalyx of the uterine luminal epithelium in the rat undergoes considerable reduction before implantation. In particular, the reduction of some mucins is necessary to facilitate blastocyst adhesion and subsequent implantation. The present study investigated the localisation, abundance and hormonal control of two mucin proteins, Muc13 and Muc15, in rat uterine epithelial cells during early pregnancy to determine whether they are likely to play a role in uterine receptivity for implantation. Muc13 and Muc15 are localised to the uterine luminal epithelium but show a presence and an absence, respectively, at the apical cell surface at the time of implantation. This localisation corresponds to changes in the molecular weights of Muc13 and Muc15, as shown with western blotting analysis. Furthermore, the localisation of Muc13 and Muc15 was shown to be controlled by the ovarian hormones, oestrogen and progesterone, and they were also localised in preimplantation rat blastocysts. Our results suggest that Muc15 may operate in an anti-adhesive capacity to prevent implantation while Muc13 potentially functions in either an adhesive or cell-signalling role in the events of implantation.

The mucin-type glycosylating enzyme polypeptide N-acetylgalactosaminyltransferase 14 promotes the migration of ovarian cancer by modifying mucin 13

A high expression of O-glycosylated proteins is one of the prominent characteristics of ovarian carcinoma cells associated with cell migration, which would be attributed to the upregulated expression of glycosyltransferases. Therefore, elucidating glycosyltransferases and their substrates may improve our understanding of their roles in tumor metastasis. In the present study, we reported that knockdown of polypeptide N-acetylgalactosaminyltransferase 14 (GALNT14) by small interfering RNA significantly suppressed the cell migration and altered cellular morphology. Immunoprecipitation and western blot analyses indicated that GALNT14 contributed to the glycosylation of transmembrane mucin 13 (MUC13), which was significantly higher in ovarian cancer cells compared with the normal/benign ovary tissues. Furthermore, interleukin-8 (IL-8), which could regulate the migration ability of epithelial ovarian cancer (EOC) cells, had no remarkable effect on the expression of GALNT14 and the tumor-associated carbohydrate epitope Tn antigen. In addition, extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor modulated the expression levels of GALNT14. Our findings provide evidence that GALNT14 may contribute to ovarian carcinogenesis through aberrant glycosylation of MUC13, but not through the IL-8 pathway. These data provide novel insights into understanding the function of MUC13 on neoplasm metastasis and may aid in the development of new anticancer drugs for EOC.

Mucins as diagnostic and prognostic biomarkers in a fish-parasite model: transcriptional and functional analysis

Mucins are O-glycosylated glycoproteins present on the apex of all wet-surfaced epithelia with a well-defined expression pattern, which is disrupted in response to a wide range of injuries or challenges. The aim of this study was to identify mucin gene sequences of gilthead sea bream (GSB), to determine its pattern of distribution in fish tissues and to analyse their transcriptional regulation by dietary and pathogenic factors. Exhaustive search of fish mucins was done in GSB after de novo assembly of next-generation sequencing data hosted in the IATS transcriptome database (www.nutrigroup-iats.org/seabreamdb). Six sequences, three categorized as putative membrane-bound mucins and three putative secreted-gel forming mucins, were identified. The transcriptional tissue screening revealed that Muc18 was the predominant mucin in skin, gills and stomach of GSB. In contrast, Muc19 was mostly found in the oesophagus and Muc13 was along the entire intestinal tract, although the posterior intestine exhibited a differential pattern with a high expression of an isoform that does not share a clear orthologous in mammals. This mucin was annotated as intestinal mucin (I-Muc). Its RNA expression was highly regulated by the nutritional background, whereas the other mucins, including Muc2 and Muc2-like, were expressed more constitutively and did not respond to high replacement of fish oil (FO) by vegetable oils (VO) in plant protein-based diets. After challenge with the intestinal parasite Enteromyxum leei, the expression of a number of mucins was decreased mainly in the posterior intestine of infected fish. But, interestingly, the highest down-regulation was observed for the I-Muc. Overall, the magnitude of the changes reflected the intensity and progression of the infection, making mucins and I-Muc, in particular, reliable markers of prognostic and diagnostic value of fish intestinal health.

An optimal mRNA marker for OSNA (One-step nucleic acid amplification) based lymph node metastasis detection in colorectal cancer patients

BACKGROUND

We previously reported that the one-step nucleic acid amplification assay is effective for lymph node metastasis detection in breast cancer patients. This paper describes the identification of CK19 mRNA as an optimal marker and its cut-off value for use in the detection of one-step nucleic acid amplification-based lymph node metastasis in colorectal cancer patients.

METHODS

Candidate mRNA markers selected from the genome-wide expressed sequence tag database were evaluated by quantitative RT-PCR using a mixture of metastasis-positive and another mixture of metastasis-negative lymph nodes (n = 5 each), followed by quantitative RT-PCR using metastasis-positive and -negative lymph nodes (n = 10 each) from 20 patients. The one-step nucleic acid amplification assay for mRNA markers selected above was examined using 28 positive lymph nodes from 19 patients and 38 negative lymph nodes from the 11 pN0 patients.

RESULTS

Quantitative RT-PCR analyses of the 98 mRNAs selected from the genome-wide expressed sequence tag database and the subsequent quantitative RT-PCR analyses of the nine mRNAs selected above indicated that CK19 and CEA mRNAs have the highest capability for distinguishing between positive and negative lymph nodes. CK19, CEA and CK20 mRNAs were evaluated by the one-step nucleic acid amplification assay. An area under a receiver-operating-characteristic curve for CK19 mRNA (0.999) was slightly larger than that for CEA mRNA (0.946; P = 0.062) and significantly larger that than for CK20 mRNA (0.875; P = 0.006).

CONCLUSION

We found that CK19 mRNA has the best diagnostic performance and its cut-off value for discriminating positive from negative lymph nodes can be set in the range of 75-500 copies/µl with 96.4% sensitivity and 100% specificity.

Mucins and toll-like receptors: kith and kin in infection and cancer

Inflammation is underlying biological phenomenon common in infection and cancer. Mucins are glycoproteins which establish a physical barrier for undesirable entry of foreign materials through epithelial surfaces. A deregulated expression and an anomalous glycosylation pattern of mucins are known in large number of cancers. TLRs are class of receptors which recognize the molecular patterns of invading pathogens and activate complex inflammatory pathways to clear them. Aberrant expression of TLRs is observed in many cancers. A highly orchestrated action of mucins and TLRs is well evolved host defence mechanism; however, a link between the two in other non-infectious conditions has received less attention. Here we present an overview as to how mucins and TLRs give protection to the host and are deregulated during carcinogenesis. Further, we propose the possible mechanisms of cross-regulation between them in pathogenesis of cancer. As both mucins and TLRs are therapeutically important class of molecules, an understanding of the underlying molecular mechanisms connecting the two will open new avenues for the therapeutic targeting of cancer.

Increased expression and aberrant localization of mucin 13 in metastatic colon cancer

MUC13 is a newly identified transmembrane mucin. Although MUC13 is known to be overexpressed in ovarian and gastric cancers, limited information is available regarding the expression of MUC13 in metastatic colon cancer. Herein, we investigated the expression profile of MUC13 in colon cancer using a novel anti-MUC13 monoclonal antibody (MAb, clone ppz0020) by immunohistochemical (IHC) analysis. A cohort of colon cancer samples and tissue microarrays containing adjacent normal, non-metastatic colon cancer, metastatic colon cancer, and liver metastasis tissues was used in this study to investigate the expression pattern of MUC13. IHC analysis revealed significantly higher (p<0.001) MUC13 expression in non-metastatic colon cancer samples compared with faint or very low expression in adjacent normal tissues. Interestingly, metastatic colon cancer and liver metastasis tissue samples demonstrated significantly (p<0.05) higher cytoplasmic and nuclear MUC13 expression compared with non-metastatic colon cancer and adjacent normal colon samples. Moreover, cytoplasmic and nuclear MUC13 expression correlated with larger and poorly differentiated tumors. Four of six tested colon cancer cell lines also expressed MUC13 at RNA and protein levels. These studies demonstrate a significant increase in MUC13 expression in metastatic colon cancer and suggest a correlation between aberrant MUC13 localization (cytoplasmic and nuclear expression) and metastatic colon cancer.

MUC13 mucin augments pancreatic tumorigenesis

The high death rate of pancreatic cancer is attributed to the lack of reliable methods for early detection and underlying molecular mechanisms of its aggressive pathogenesis. Although MUC13, a newly identified transmembrane mucin, is known to be aberrantly expressed in ovarian and gastro-intestinal cancers, its role in pancreatic cancer is unknown. Herein, we investigated the expression profile and functions of MUC13 in pancreatic cancer progression. The expression profile of MUC13 in pancreatic cancer was investigated using a recently generated monoclonal antibody (clone PPZ0020) and pancreatic tissue microarrays. The expression of MUC13 was significantly (P < 0.005) higher in cancer samples compared with normal/nonneoplastic pancreatic tissues. For functional analyses, full-length MUC13 was expressed in MUC13 null pancreatic cancer cell lines, MiaPaca and Panc1. MUC13 overexpression caused a significant (P < 0.05) increase in cell motility, invasion, proliferation, and anchorage-dependent or -independent clonogenicity while decreasing cell-cell and cell-substratum adhesion. Exogenous MUC13 expression significantly (P < 0.05) enhanced pancreatic tumor growth and reduced animal survival in a xenograft mouse model. These tumorigenic characteristics correlated with the upregulation/phosphorylation of HER2, p21-activated kinase 1 (PAK1), extracellular signal-regulated kinase (ERK), Akt, and metastasin (S100A4), and the suppression of p53. Conversely, suppression of MUC13 in HPAFII pancreatic cancer cells by short hairpin RNA resulted in suppression of tumorigenic characteristics, repression of HER2, PAK1, ERK, and S100A4, and upregulation of p53. MUC13 suppression also significantly (P < 0.05) reduced tumor growth and increased animal survival. These results imply a role of MUC13 in pancreatic cancer and suggest its potential use as a diagnostic and therapeutic target.

Verification of a biomarker discovery approach for detection of Down syndrome in amniotic fluid via multiplex selected reaction monitoring (SRM) assay

Prenatal screening test for Down syndrome (DS) can be improved by discovery of novel biomarkers. A multiplex selected reaction monitoring (SRM) assay was developed to test previously identified thirteen candidate proteins in amniotic fluid (AF). One unique peptide was selected for each protein based on discovery data, while three MS/MS transitions were selected based on intelligent SRM results. For one of the candidates, matrix metalloproteinase-2 (MMP2), ELISA was also performed to validate SRM results in AF and to test serum samples. Comparison of AF samples from DS versus controls via SRM assay revealed five proteins that were differentially expressed. Bile salt-activated lipase, mucin-13, carboxypeptidase A1, and dipeptidyl peptidase 4 showed a decrease in DS-affected AF, and MMP2 showed an increase, in comparison to controls (P<0.05). Discovery-based spectral counting ratios and SRM ratios showed a strong correlation, and MMP2 ELISA further confirmed the validity of the SRM data. Potential implications of differentially expressed proteins during fetal development are proposed. Our data also shows that SRM can provide a high-throughput and accurate platform for biomarker verification.

Mucin 13: structure, function, and potential roles in cancer pathogenesis

Mucin 13 (MUC13) is a high-molecular-weight transmembrane glycoprotein that is frequently and aberrantly expressed in a variety of epithelial carcinomas, including gastric, colorectal, and ovarian cancers. On the basis of the high expression of MUC13 in cancer cells as well as recent laboratory findings suggesting a malignant phenotype of MUC13-transfected cell lines, the oncogenic potential of MUC13 has emerged. The various functional domains of MUC13 may confer oncogenic potential to MUC13. For example, the bulky extracellular domain with extensive modification with glycan chains may prevent cell-cell and cell-extracellular matrix binding whereas the cytoplasmic tail containing serine and tyrosine residues for potential phosphorylation may participate in cell signaling. MUC13 exhibits the characteristics suitable as an early marker for cancer screening and presents a promising target for antibody-guided targeted therapy.

Genome-wide expression patterns associated with oncogenesis and sarcomatous transdifferentation of cholangiocarcinoma

Background

The molecular mechanisms of CC (cholangiocarcinoma) oncogenesis and progression are poorly understood. This study aimed to determine the genome-wide expression of genes related to CC oncogenesis and sarcomatous transdifferentiation.

Methods

Genes that were differentially expressed between CC cell lines or tissues and cultured normal biliary epithelial (NBE) cells were identified using DNA microarray technology. Expressions were validated in human CC tissues and cells.

Results

Using unsupervised hierarchical clustering analysis of the cell line and tissue samples, we identified a set of 342 commonly regulated (>2-fold change) genes. Of these, 53, including tumor-related genes, were upregulated, and 289, including tumor suppressor genes, were downregulated (<0.5 fold change). Expression of SPP1, EFNB2, E2F2, IRX3, PTTG1, PPARγ, KRT17, UCHL1, IGFBP7 and SPARC proteins was immunohistochemically verified in human and hamster CC tissues. Additional unsupervised hierarchical clustering analysis of sarcomatoid CC cells compared to three adenocarcinomatous CC cell lines revealed 292 differentially upregulated genes (>4-fold change), and 267 differentially downregulated genes (<0.25 fold change). The expression of 12 proteins was validated in the CC cell lines by immunoblot analysis and immunohistochemical staining. Of the proteins analyzed, we found upregulation of the expression of the epithelial-mesenchymal transition (EMT)-related proteins VIM and TWIST1, and restoration of the methylation-silenced proteins LDHB, BNIP3, UCHL1, and NPTX2 during sarcomatoid transdifferentiation of CC.

Conclusion

The deregulation of oncogenes, tumor suppressor genes, and methylation-related genes may be useful in identifying molecular targets for CC diagnosis and prognosis.

Gene expression profiling of metaplastic lineages identifies CDH17 as a prognostic marker in early stage gastric cancer

BACKGROUND & AIMS

Intestinal metaplasia (IM) and spasmolytic polypeptide-expressing metaplasia (SPEM) are precursors to gastric carcinogenesis. We sought to identify molecular biomarkers of gastric metaplasias and gastric cancer by gene expression profiling of metaplastic lesions from patients.

METHODS

Complementary DNA microarray analysis was performed on IM and SPEM cells isolated from patient samples using laser capture microdissection. Up-regulated transcripts in metaplastic lesions were confirmed by immunostaining analysis in IM, SPEM, and gastric cancer tissues. Proteins that were highly expressed specifically in gastric cancer tissues were analyzed for their association with survival in a test set (n = 450) and a validation set (n = 502) of samples from gastric cancer patients.

RESULTS

Compared with normal chief cells, 858 genes were differentially expressed in IM or SPEM samples. Immunostaining was detected for 12 proteins, including 3 new markers of IM (ACE2, LGALS4, AKR1B10) and 3 of SPEM (OLFM4, LYZ, DPCR1). Of 13 proteins expressed in IM or SPEM, 8 were expressed by 17%-50% of human gastric cancer tissues (MUC13, OLFM4, CDH17, KRT20, MUC5AC, LGALS4, AKR1B10, REG4). Expression of CDH17 or MUC13 correlated with patient survival in the test and validation sets. Multivariate analysis showed that CDH17 was an independent prognostic factor in patients with stage I or node-negative disease.

CONCLUSIONS

We identified several novel biomarkers for IM, SPEM, and gastric cancer using gene expression profiling of human metaplastic lesions. Expression of CDH17 and MUC13 was up-regulated in gastric cancer tissues. CDH17 is a promising prognostic marker for early stage gastric cancer.

Membrane-bound mucins: the mechanistic basis for alterations in the growth and survival of cancer cells

Mucins (MUC) are high molecular weight O-linked glycoproteins whose primary functions are to hydrate, protect, and lubricate the epithelial luminal surfaces of the ducts within the human body. The MUC family is comprised of large secreted gel forming and transmembrane (TM) mucins. MUC1, MUC4, and MUC16 are the well-characterized TM mucins and have been shown to be aberrantly overexpressed in various malignancies including cystic fibrosis, asthma, and cancer. Recent studies have uncovered the unique roles of these mucins in the pathogenesis of cancer. These mucins possess specific domains that can make complex associations with various signaling pathways, impacting cell survival through alterations of cell growth, proliferation, death, and autophagy. The cytoplasmic domain of MUC1 serves as a scaffold for interaction with various signaling proteins. On the other hand, MUC4 mediates its effect by stabilizing and enhancing the activity of growth factor receptor ErbB2. MUC16, previously known as CA125, is a well-known serum marker for the diagnosis of ovarian cancer and has a key role in stimulation and dissemination of ovarian cancer cells by interacting with mesothelin and galectin. Therefore, herein we discuss the function and divergent mechanisms of MUC1, MUC4, and MUC16 in carcinogenesis in the context of alteration in cell growth and survival.

Lectins from the Red Marine Algal Species Bryothamnion seaforthii and Bryothamnion triquetrum as Tools to Differentiate Human Colon Carcinoma Cells

The carbohydrate-binding activity of the algal lectins from the closely related red marine algal species Bryothamnion triquetrum (BTL) and Bryothamnion seaforthii (BSL) was used to differentiate human colon carcinoma cell variants with respect to their cell membrane glyco-receptors. These lectins interacted with the cells tested in a dose-dependent manner. Moreover, the fluorescence spectra of both lectins clearly differentiated the cells used as shown by FACS profiles. Furthermore, as observed by confocal microscopy, BTL and BSL bound to cell surface glycoproteins underwent intense internalization, which makes them possible tools in targeting strategies.

Mucins in cancer: function, prognosis and therapy

Epithelia are protected from adverse conditions by a mucous barrier. The secreted and transmembrane mucins that constitute the mucous barrier are largely unrecognized as effectors of carcinogenesis. However, both types of mucins are intimately involved in inflammation and cancer. Moreover, diverse human malignancies overexpress transmembrane mucins to exploit their role in signalling cell growth and survival. Mucins have thus been identified as markers of adverse prognosis and as attractive therapeutic targets. Notably, the findings that certain transmembrane mucins induce transformation and promote tumour progression have provided the experimental basis for demonstrating that inhibitors of their function are effective as anti-tumour agents in preclinical models.

Current status of mucins in the diagnosis and therapy of cancer

Mucins are the most abundant high molecular weight glycoproteins in mucus. Their nature and glycosylation content dictates the biochemical and biophysical properties of viscoelastic secretions, pointing out an important role in diverse biological functions, such as differentiation, cell adhesions, immune responses, and cell signaling. Mucins are expressed in tubular organs by specialized epithelial cells in the body. Their aberrant expression is well documented in a variety of inflammatory or malignant diseases. From a prognosis point of view, their expression and alterations in glycosylation are associated with the development and progression of malignant diseases. Therefore, mucins can be used as valuable markers to distinguish between normal and disease conditions. Indeed, this alteration in glycosylation patterns generates several epitopes in the oligosaccharide side chains that can be used as diagnostic and/or prognostic markers. Furthermore, these characteristic tumor-associated epitopes are extensively used as appropriate immunotargets of malignant epithelial cells. Therefore, in an effort to detect and treat cancer at the earliest stage possible, mucins are analyzed as potential markers of disease for diagnosis, progression, and for therapeutic purposes. In this review, we focused on the current status of the distribution of mucins in normal and pathologic conditions and their clinical use both in cancer diagnosis and therapeutics treatments.