Immunohistochemical study of mucin carbohydrates and core proteins in human pancreatic tumors

Deciphering Protein O-GalNAcylation: Method Development and Disease Implication

Mucin-type O-glycosylation is an important protein post-translational modification that is abundantly expressed on cell surface proteins. Protein O-glycosylation plays a variety of roles in cellular biological functions including protein structure and signal transduction to the immune response. Cell surface mucins are highly O-glycosylated and are the main substance of the mucosal barrier that protects the gastrointestinal or respiratory tract from infection by pathogens or microorganisms. Dysregulation of mucin O-glycosylation may impair mucosal protection against pathogens that can invade cells to trigger infection or immune evasion. Truncated O-glycosylation, also known as Tn antigen or O-GalNAcylation, is highly upregulated in diseases such cancer, autoimmune disorders, neurodegenerative diseases, and IgA nephropathy. Characterization of O-GalNAcylation helps decipher the role of Tn antigen in physiopathology and therapy. However, the analysis of O-glycosylation, specifically the Tn antigen, remains challenging due to the lack of reliable enrichment and identification assays compared to N-glycosylation. Here, we summarize recent advances in analytical methods for O-GalNAcylation enrichment and identification and highlight the biological role of the Tn antigen in various diseases and the clinical implications of identifying aberrant O-GalNAcylation.

Applications of tissue-specific and cancer-selective gene promoters for cancer diagnosis and therapy

Current treatment of solid tumors with standard of care chemotherapies, radiation therapy and/or immunotherapies are often limited by severe adverse toxic effects, resulting in a narrow therapeutic index. Cancer gene therapy represents a targeted approach that in principle could significantly reduce undesirable side effects in normal tissues while significantly inhibiting tumor growth and progression. To be effective, this strategy requires a clear understanding of the molecular biology of cancer development and evolution and developing biological vectors that can serve as vehicles to target cancer cells. The advent and fine tuning of omics technologies that permit the collective and spatial recognition of genes (genomics), mRNAs (transcriptomics), proteins (proteomics), metabolites (metabolomics), epiomics (epigenomics, epitranscriptomics, and epiproteomics), and their interactomics in defined complex biological samples provide a roadmap for identifying crucial targets of relevance to the cancer paradigm. Combining these strategies with identified genetic elements that control target gene expression uncovers significant opportunities for developing guided gene-based therapeutics for cancer. The purpose of this review is to overview the current state and potential limitations in developing gene promoter-directed targeted expression of key genes and highlights their potential applications in cancer gene therapy.

A Sweet Warning: Mucin-Type O-Glycans in Cancer

Glycosylation is a common post-translational modification process of proteins. Mucin-type O-glycosylation is an O-glycosylation that starts from protein serine/threonine residues. Normally, it is involved in the normal development and differentiation of cells and tissues, abnormal glycosylation can lead to a variety of diseases, especially cancer. This paper reviews the normal biosynthesis of mucin-type O-glycans and their role in the maintenance of body health, followed by the mechanisms of abnormal mucin-type O-glycosylation in the development of diseases, especially tumors, including the effects of Tn, STn, T antigen, and different glycosyltransferases, with special emphasis on their role in the development of gastric cancer. Finally, tumor immunotherapy targeting mucin-type O-glycans was discussed.

Role of tumor cell sialylation in pancreatic cancer progression

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest malignancies and is currently the third leading cause of cancer death. The aggressiveness of PDAC stems from late diagnosis, early metastasis, and poor efficacy of current chemotherapies. Thus, there is an urgent need for effective biomarkers for early detection of PDAC and development of new therapeutic strategies. It has long been known that cellular glycosylation is dysregulated in pancreatic cancer cells, however, tumor-associated glycans and their cognate glycosylating enzymes have received insufficient attention as potential clinical targets. Aberrant glycosylation affects a broad range of pathways that underpin tumor initiation, metastatic progression, and resistance to cancer treatment. One of the prevalent alterations in the cancer glycome is an enrichment in a select group of sialylated glycans including sialylated, branched N-glycans, sialyl Lewis antigens, and sialylated forms of truncated O-glycans such as the sialyl Tn antigen. These modifications affect the activity of numerous cell surface receptors, which collectively impart malignant characteristics typified by enhanced cell proliferation, migration, invasion and apoptosis-resistance. Additionally, sialic acids on tumor cells engage inhibitory Siglec receptors on immune cells to dampen anti-tumor immunity, further promoting cancer progression. The goal of this review is to summarize the predominant changes in sialylation occurring in pancreatic cancer, the biological functions of sialylated glycoproteins in cancer pathogenesis, and the emerging strategies for targeting sialoglycans and Siglec receptors in cancer therapeutics.

Immunohistochemical Coexpression of MUC1 and MUC4 in Oral Leukoplakia and Oral Squamous Cell Carcinoma

MUC1 and MUC4 are two transmembranous proteins, which have been seen to express aberrantly in various human neoplasms and advocated as independent prognostic markers. Till now no extensive studies have been carried out on combined expression of MUC1 and MUC4 in oral leukoplakia and Oral squamous cell carcinoma. This study is an endeavour to evaluate Immunohistochemical coexpression of MUC1 and MUC4 in Oral Leukoplakia and Oral squamous cell carcinoma and furthr establish them as prognostic markers. Immunohistochemical analysis of MUC1 and MUC4 was done on 24 cases of Oral squamous cell carcinoma, 24 cases of leukoplakia and 12 normal oral mucosal tissues. Chi square test and one way ANOVA test were employed for statistical analysis. Normal oral mucosa and leukoplakia group showed higher frequency of negative immunoexpression compared to oral squamous cell carcinoma group. Furthur in Oral squamous cell carcinoma group, higher frequency of double positive coexpression in well and moderately differentiated oral squamous cell carcinoma and single positive coexpression in poorly differentiated oral squamous cell carcinoma was obtained. A definite rise of immunoexpression of MUC1 and MUC4 was observed from normal oral mucosa to leukoplakia to oral squamous cell carcinoma indicative of their contribution as diagnostic and prognostic markers.

Quantitative assessment of the diagnostic role of mucin family members in pancreatic cancer: a meta-analysis

Background

The use of mucins (MUC) as specific biomarkers for various malignancies has recently emerged. MUC1, MUC4, MUC5AC, and MUC16 can be detected at different stages of pancreatic cancer (PC), and can be valuable for indicating the initiation and progression of this disease. However, the diagnostic significance of the mucin family in patients with PC remains disputed. Herein, we assessed the diagnostic accuracy of mucins in PC using a meta-analysis.

Methods

We searched the PubMed, Cochrane Library, Institute for Scientific Information (ISI) Web of Science, Embase, and Chinese databases from their date of inception to June 1, 2020 to identify studies assessing the diagnostic performance of mucins in PC. The estimations of diagnostic indicators in selected studies were extracted for further analysis by Meta-DiSc software. Publication bias was assessed using Deeks’ funnel plot asymmetry test.

Results

Our meta-analysis included 34 studies. The pooled accuracy indicators of MUC1 in PC including the sensitivity, specificity, diagnostic odds ratio (DOR), positive likelihood ratio (PLR), and negative likelihood ratio (NLR) (with 95% confidence intervals) were 0.84 (0.82–0.86), 0.60 (0.56–0.64), 18.37 (9.18–36.78), 2.62 (1.79–3.86), and 0.22 (0.15–0.33), respectively. The area under the summary receiver operating characteristic (SROC) curve was 0.8875 and the Q index was 0.8181. Quantitative random-effects meta-analysis of MUC4 in PC using the summary (ROC) curve model revealed a pooled sensitivity of 0.86 (95% confidence interval, 0.82–0.89) and specificity of 0.88 (95% confidence interval, 0.85–0.91). In addition, the meta-analysis of MUC5AC in PC diagnosis also showed a high sensitivity and specificity of 0.71 (95% confidence interval, 0.65–0.76) and 0.60 (95% confidence interval, 0.53–0.66), respectively. Regarding MUC16, the area under the summary ROC curve and Q index were 0.9185 and 0.8516, respectively.

Conclusions

In summary, our results suggested a good diagnostic accuracy of several crucial mucins in PC. Mucins may serve as optional indicators in PC examination, and further research is warranted to investigate the role of mucins as potential clinical biomarkers.

Mucins in pancreatic cancer: A well-established but promising family for diagnosis, prognosis and therapy

Mucins are a family of multifunctional glycoproteins that mostly line the surface of epithelial cells in the gastrointestinal tract and exert pivotal roles in gut lubrication and protection. Pancreatic cancer is a lethal disease with poor early diagnosis, limited therapeutic effects, and high numbers of cancer‐related deaths. In this review, we introduce the expression profiles of mucins in the normal pancreas, pancreatic precursor neoplasia and pancreatic cancer. Mucins in the pancreas contribute to biological processes such as the protection, lubrication and moisturization of epithelial tissues. They also participate in the carcinogenesis of pancreatic cancer and are used as diagnostic biomarkers and therapeutic targets. Herein, we discuss the important roles of mucins that lead to the lethality of pancreatic adenocarcinoma, particularly MUC1, MUC4, MUC5AC and MUC16 in disease progression, and present a comprehensive analysis of the clinical application of mucins and their promising roles in cancer treatment to gain a better understanding of the role of mucins in pancreatic cancer.

MUC-1 aptamer targeted superparamagnetic iron oxide nanoparticles for magnetic resonance imaging of pancreatic cancer in vivo and in vitro experiment

This study aims to explore the ability of magnetic resonance imaging (MRI) in mucin 1 (MUC1) modified superparamagnetic iron oxide nanoparticle (SPION) targeting human pancreatic cancer (PC). The MUC1 target-directed probe was prepared through MUC1 conjugated to SPION using the chemical method to assess its physiochemical characteristics, including hydration diameter, surface charge, and magnetic resonance signal. The cytotoxicity of MUC1-USPION was verified by MTS assay. BxPC-3 was cultured with MUC1-USPION and SPION in different concentrations. The combined condition of the targeted probes and cells were observed through Prussian blue staining. The nude mice model of pancreatic cancer was established to investigate the application of the probe. MRI was performed to determine the intensity of the signal of the transplanted tumor, while immunohistochemistry and Western blot analysis were performed to detect the expression of MUC1 after taking the transplanted tumor specimen. The particle size of the prepared molecular probe was 63.5 ± 3.2 nm, and the surface charge was 10.2 mV. Furthermore, the probe solution could significantly reduce the MRI at T₂ , and the magnetic resonance transverse relaxation rate (ΔR² ) has a linear relationship with the concentration of iron in the solution. The cell viability of MUC1-USPION in different concentrations revealed no statistical difference, according to the MTS assay. In vitro, the MRI demonstrated decreased T2WI signal intensity in both groups, especially the targeting group. In vivo, MUC1 could selectively accumulate in the nude mice model, and significantly reduce the T₂ signal strength. In subsequent experiments, the expression of MUC1 was high in pancreatic cancer tissues, but low in normal pancreatic tissues, as determined by immunohistochemistry and Western blot analysis. The prepared samples can be combined with pancreatic cancer tissue specificity by in vivo imaging, providing reliable early in vivo imaging data for disease diagnosis.

Pancreatic Cystic Lesions: Pathogenesis and Malignant Potential

Pancreatic cancer remains one of the most lethal cancers despite extensive research. Further understanding of precursor lesions may enhance the ability to treat and prevent pancreatic cancer. Pancreatic cystic lesions (PCLs) with malignant potential include: mucinous PCLs (intraductal papillary mucinous neoplasms and mucinous cystic neoplasm), solid pseudopapillary tumors and cystic neuroendocrine tumors. This review summarizes the latest literature describing what is known about the pathogenesis and malignant potential of these PCLs, including unique epidemiological, radiological, histological, genetic and molecular characteristics.

Tumor Markers in the Diagnosis, Monitoring and Therapy of Pancreatic Cancer: State of the Art

The present review focuses on the utility of serum tumor markers in screening, diagnosis, prognosis and monitoring of pancreatic cancer. Serum determination of all tumor markers studied offers no help in screening or early diagnosis of pancreatic cancer. For diagnosis, blood group-related antigens, in particular CA 19-9, are considered the best indicators of this neoplasm. However, as occurs with other glycoproteic tumor markers, the circulating levels of CA 19-9 are significantly influenced by jaundice, probably because its liver metabolism is reduced. Therefore, the finding of elevated CA 19-9 levels in jaundiced patients has to be evaluated with caution. Since pancreatic cancer recurrences are not susceptible to treatment, the clinical role of widespread use of tumor marker determination in follow-up programs is limited and calls for a critical evaluation.

Glycosyltransferase Gene Expression Profiles Classify Cancer Types and Propose Prognostic Subtypes

Aberrant glycosylation in tumours stem from altered glycosyltransferase (GT) gene expression but can the expression profiles of these signature genes be used to classify cancer types and lead to cancer subtype discovery? The differential structural changes to cellular glycan structures are predominantly regulated by the expression patterns of GT genes and are a hallmark of neoplastic cell metamorphoses. We found that the expression of 210 GT genes taken from 1893 cancer patient samples in The Cancer Genome Atlas (TCGA) microarray data are able to classify six cancers; breast, ovarian, glioblastoma, kidney, colon and lung. The GT gene expression profiles are used to develop cancer classifiers and propose subtypes. The subclassification of breast cancer solid tumour samples illustrates the discovery of subgroups from GT genes that match well against basal-like and HER2-enriched subtypes and correlates to clinical, mutation and survival data. This cancer type glycosyltransferase gene signature finding provides foundational evidence for the centrality of glycosylation in cancer.

How Grim is Pancreatic Cancer?

Pancreatic ductal carcinoma continues to be the most lethal malignancy with rising incidence. It is the fourth most common cause of cancer death in the western world due to its low treatment success rate. In addition, because of its rapid growth and silent course, diagnosis is often only established in the advanced stages. As one of the most aggressive malignancies, the treatment of this disease is a great challenge to clinicians. This paper reviewed the natural history of pancreatic cancer, the current clinical practice and the future in pancreatic cancer management.

Short O-GalNAc glycans: regulation and role in tumor development and clinical perspectives

BACKGROUND

While the underlying causes of cancer are genetic modifications, changes in cellular states mediate cancer development. Tumor cells display markedly changed glycosylation states, of which the O-GalNAc glycans called the Tn and TF antigens are particularly common. How these antigens get over-expressed is not clear. The expression levels of glycosylation enzymes fail to explain it.

SCOPE OF REVIEW

We describe the regulation of O-GalNAc glycosylation initiation and extension with emphasis on the initiating enzymes ppGalNAcTs (GALNTs), and introduce the GALA pathway--a change in GALNTs compartmentation within the secretory pathway that regulates Tn levels. We discuss the roles of O-GalNAc glycans and GALNTs in tumorigenic processes and finally consider diagnostic and therapeutic perspectives.

MAJOR CONCLUSIONS

Contrary to a common hypothesis, short O-glycans in tumors are not the result of an incomplete glycosylation process but rather reveal the activation of regulatory pathways. Surprisingly, high Tn levels reveal a major shift in the O-glycoproteome rather than a shortening of O-glycans. These changes are driven by membrane trafficking events.

GENERAL SIGNIFICANCE

Many attempts to use O-glycans for biomarker, antibody and therapeutic vaccine development have been made, but suffer limitations including poor sensitivity and/or specificity that may in part derive from lack of a mechanistic understanding. Deciphering how short O-GalNAc glycans are regulated would open new perspectives to exploit this biology for therapeutic usage. This article is part of a Special Issue entitled "Glycans in personalised medicine" Guest Editor: Professor Gordan Lauc.

Molecular Imaging with MRI: Potential Application in Pancreatic Cancer

Despite the variety of approaches that have been improved to achieve a good understanding of pancreatic cancer (PC), the prognosis of PC remains poor, and the survival rates are dismal. The lack of early detection and effective interventions is the main reason. Therefore, considerable ongoing efforts aimed at identifying early PC are currently being pursued using a variety of methods. In recent years, the development of molecular imaging has made the specific targeting of PC in the early stage possible. Molecular imaging seeks to directly visualize, characterize, and measure biological processes at the molecular and cellular levels. Among different imaging technologies, the magnetic resonance (MR) molecular imaging has potential in this regard because it facilitates noninvasive, target-specific imaging of PC. This topic is reviewed in terms of the contrast agents for MR molecular imaging, the biomarkers related to PC, targeted molecular probes for MRI, and the application of MRI in the diagnosis of PC.

Thirty years of experience with intraductal papillary mucinous neoplasm of the pancreas: from discovery to international consensus

BACKGROUND

Intraductal papillary mucinous neoplasm (IPMN) of the pancreas is characterized by intraductal papillary proliferation of mucin-producing epithelial cells that exhibit various degrees of dysplasia. IPMN is classified as the main duct type (MD-IPMN) and the branch duct type (BD-IPMN) according to the location of involvement, and into four histological subtypes (gastric, intestinal, pancreatobiliary, and oncocytic) according to the histomorphological and immunohistochemical characteristics. Mucin core protein expression correlates with the biological behavior and prognosis of the tumor. DNA analysis has shown that IPMN is associated with a number of gene mutations, but the roles of many of these mutations require further investigation. Most patients with MD-IPMN undergo tumor resection. Patients with BD-IPMN who do not undergo resection may develop malignant change, and concomitant separate pancreatic cancer occurs in 2-10% of patients with IPMN. Patients with a strong family history may develop multiple BD-IPMNs as well as concomitant pancreatic cancer. Malignant changes are relatively easy to detect, especially by endoscopic ultrasonography (EUS), but the optimal surveillance protocol is currently unclear.

KEY MESSAGES

The 2012 guidelines for the management of IPMN recommend that patients with 'high-risk stigmata' (obstructive jaundice, enhanced solid component, and main pancreatic duct size ≥10 mm) should undergo resection. Patients with 'worrisome features' (cyst size ≥3 cm, thickened enhanced cyst walls, non-enhanced mural nodules, main pancreatic duct size 5-9 mm, abrupt change in main pancreatic duct caliber with distal pancreatic atrophy, lymphadenopathy, and clinical acute pancreatitis) should be evaluated by EUS. EUS is a more sensitive test than computed tomography or magnetic resonance imaging for the early detection of malignancy.

CONCLUSIONS

Most patients with MD-IPMN should undergo tumor resection. Patients with BD-IPMN who do not undergo resection should undergo careful surveillance including EUS for the early detection of malignant change and separate pancreatic cancer.

Challenges in Antibody Development against Tn and Sialyl-Tn Antigens

The carbohydrate antigens Tn and sialyl-Tn (STn) are expressed in most carcinomas and usually absent in healthy tissues. These antigens have been correlated with cancer progression and poor prognosis, and associated with immunosuppressive microenvironment. Presently they are used in clinical trials as therapeutic vaccination, but with limited success due to their low immunogenicity. Alternatively, anti-Tn and/or STn antibodies may be used to harness the immune system against tumor cells. Whilst the development of antibodies against these antigens had a boost two decades ago for diagnostic use, so far no such antibody entered into clinical trials. Possible limitations are the low specificity and efficiency of existing antibodies and that novel antibodies are still necessary. The vast array of methodologies available today will allow rapid antibody development and novel formats. Following the advent of hybridoma technology, the immortalization of human B cells became a methodology to obtain human monoclonal antibodies with better specificity. Advances in molecular biology including phage display technology for high throughput screening, transgenic mice and more recently molecularly engineered antibodies enhanced the field of antibody production. The development of novel antibodies against Tn and STn taking advantage of innovative technologies and engineering techniques may result in innovative therapeutic antibodies for cancer treatment.

Challenges in Antibody Development against Tn and Sialyl-Tn Antigens

The carbohydrate antigens Tn and sialyl-Tn (STn) are expressed in most carcinomas and usually absent in healthy tissues. These antigens have been correlated with cancer progression and poor prognosis, and associated with immunosuppressive microenvironment. Presently they are used in clinical trials as therapeutic vaccination, but with limited success due to their low immunogenicity. Alternatively, anti-Tn and/or STn antibodies may be used to harness the immune system against tumor cells. Whilst the development of antibodies against these antigens had a boost two decades ago for diagnostic use, so far no such antibody entered into clinical trials. Possible limitations are the low specificity and efficiency of existing antibodies and that novel antibodies are still necessary. The vast array of methodologies available today will allow rapid antibody development and novel formats. Following the advent of hybridoma technology, the immortalization of human B cells became a methodology to obtain human monoclonal antibodies with better specificity. Advances in molecular biology including phage display technology for high throughput screening, transgenic mice and more recently molecularly engineered antibodies enhanced the field of antibody production. The development of novel antibodies against Tn and STn taking advantage of innovative technologies and engineering techniques may result in innovative therapeutic antibodies for cancer treatment.

Challenges in Antibody Development against Tn and Sialyl-Tn Antigens

The carbohydrate antigens Tn and sialyl-Tn (STn) are expressed in most carcinomas and usually absent in healthy tissues. These antigens have been correlated with cancer progression and poor prognosis, and associated with immunosuppressive microenvironment. Presently they are used in clinical trials as therapeutic vaccination, but with limited success due to their low immunogenicity. Alternatively, anti-Tn and/or STn antibodies may be used to harness the immune system against tumor cells. Whilst the development of antibodies against these antigens had a boost two decades ago for diagnostic use, so far no such antibody entered into clinical trials. Possible limitations are the low specificity and efficiency of existing antibodies and that novel antibodies are still necessary. The vast array of methodologies available today will allow rapid antibody development and novel formats. Following the advent of hybridoma technology, the immortalization of human B cells became a methodology to obtain human monoclonal antibodies with better specificity. Advances in molecular biology including phage display technology for high throughput screening, transgenic mice and more recently molecularly engineered antibodies enhanced the field of antibody production. The development of novel antibodies against Tn and STn taking advantage of innovative technologies and engineering techniques may result in innovative therapeutic antibodies for cancer treatment.

Challenges in Antibody Development against Tn and Sialyl-Tn Antigens

The carbohydrate antigens Tn and sialyl-Tn (STn) are expressed in most carcinomas and usually absent in healthy tissues. These antigens have been correlated with cancer progression and poor prognosis, and associated with immunosuppressive microenvironment. Presently they are used in clinical trials as therapeutic vaccination, but with limited success due to their low immunogenicity. Alternatively, anti-Tn and/or STn antibodies may be used to harness the immune system against tumor cells. Whilst the development of antibodies against these antigens had a boost two decades ago for diagnostic use, so far no such antibody entered into clinical trials. Possible limitations are the low specificity and efficiency of existing antibodies and that novel antibodies are still necessary. The vast array of methodologies available today will allow rapid antibody development and novel formats. Following the advent of hybridoma technology, the immortalization of human B cells became a methodology to obtain human monoclonal antibodies with better specificity. Advances in molecular biology including phage display technology for high throughput screening, transgenic mice and more recently molecularly engineered antibodies enhanced the field of antibody production. The development of novel antibodies against Tn and STn taking advantage of innovative technologies and engineering techniques may result in innovative therapeutic antibodies for cancer treatment.