Axed MUC4 (MUC4/X) aggravates pancreatic malignant phenotype by activating integrin-β1/FAK/ERK pathway

Exploring Splicing Modulation as an Innovative Approach to Combat Pancreatic Cancer: SF3B1 Emerges as a Prognostic Indicator and Therapeutic Target

Pancreatic ductal adenocarcinoma (PDAC) poses significant challenges in terms of prognosis and treatment. Recent research has identified splicing deregulation as a new cancer hallmark. Herein, we investigated the largely uncharacterized alternative splicing profile and the key splicing factor SF3B1 in PDAC pancreatic cells and tissues as a potential discovery source of plausible drug targets and new predictive biomarkers of clinical outcome. The research involved a transcriptome-wide analysis, comparing profiles of splicing profiles in PDAC primary cells with normal ductal cells. This revealed more than 400 significant differential splicing events in genes involved in regulation of gene expression, primarily related to mRNA splicing, and metabolism of nucleic acids. PDAC cultures were highly sensitive to the SF3B1 modulators, E7107 and Pladienolide-B, showing IC50s in the low nanomolar range. These compounds induced apoptosis, associated to induction of the MCL-1/S splice variant. and reduced cell migration, associated to RON mis-splicing. In an orthotopic mouse model, E7107 showed promising results. Furthermore, we evaluated SF3B1 expression in specimens from 87 patients and found a significant association of SF3B1 expression with progression-free and overall survival. In conclusion, SF3B1 emerges as both a potential prognostic factor and therapeutic target in PDAC, impacting cell proliferation, migration, and apoptosis. These findings warrant future studies on this new therapeutic strategy against PDAC.

Study on the mechanism of magnesium calcium alloys/mineralized collagen composites mediating macrophage polarization to promote bone repair

Magnesium-based composites are a focal point in biomaterials research. However, the rapid degradation rate of magnesium alloys does not align with the healing time of bone tissue. Additionally, the host reaction caused by magnesium implantation hampers its full osteogenic potential. To maintain an appropriate microenvironment, it is important to enhance both corrosion resistance and osteogenic activity of the magnesium matrix. In this study, a composite scaffold composed of mineralized collagen and magnesium alloy was utilized to investigate the regulatory effect of mineralized collagen on mouse macrophages and evaluate its impact on mouse bone marrow mesenchymal stem cells in terms of osteogenesis, immune response, and macrophage-induced osteogenic differentiation. This experiment examined the biocompatibility of mouse bone marrow mesenchymal stem cells and macrophage-induced osteogenic differentiation in vitro, and examined the expression levels of relevant pathways proteins. Magnesium calcium alloys/mineralized collagen exhibited extensive spreading, facilitated by broad and abundant pseudopodia that firmly adhered them to the material surface and promoted growth and pseudopodia formation. The findings revealed that magnesium calcium alloy/mineralized collagen scaffold materials induced osteogenic differentiation mainly through M2 polarization of macrophages. This effect was mainly mediated by promoting the integrin α2β1-FAK-ERK1/2 signaling pathways and inhibiting the RANK signaling pathways.

Oncogenic KRAS, Mucin 4, and Activin A-Mediated Fibroblast Activation Cooperate for PanIN Initiation

Over 90% of patients with pancreatic ductal adenocarcinoma (PDAC) have oncogenic KRAS mutations. Nevertheless, mutated KRAS alone is insufficient to initiate pancreatic intraepithelial neoplasia (PanIN), the precursor of PDAC. The identities of the other factors/events required to drive PanIN formation remain elusive. Here, optic-clear 3D histology is used to analyze entire pancreases of 2-week-old Pdx1-Cre; LSL-KrasG12D/+ (KC) mice to detect the earliest emergence of PanIN and observed that the occurrence is independent of physical location. Instead, it is found that the earliest PanINs overexpress Muc4 and associate with αSMA+ fibroblasts in both transgenic mice and human specimens. Mechanistically, KrasG12D/+ pancreatic cells upregulate Muc4 through genetic alterations to increase proliferation and fibroblast recruitments via Activin A secretion and consequently enhance cell transformation for PanIN formation. Inhibition of Activin A signaling using Follistatin (FST) diminishes early PanIN-associated fibroblast recruitment, effectively curtailing PanIN initiation and growth in KC mice. These findings emphasize the vital role of interactions between oncogenic KrasG12D/+ -driven genetic alterations and induced microenvironmental changes in PanIN initiation, suggesting potential avenues for early PDAC diagnostic and management approaches.

Tetracycline antibiotics: Potential anticancer drugs

In recent years, research on tetracycline antibiotics has gradually shifted from their antibacterial effects to anticancer effects. Doxycycline, minocycline, and tigecycline as the US Food and Drug Administration (FDA) approved tetracycline antibiotics have been the main subjects of studies. Evidence indicated that they have anticancer properties and are able to control cancer progression through different mechanisms, such as anti-proliferation, anti-metastasis, and promotion of autophagy or apoptosis. In addition, studies have shown that these three tetracycline antibiotics can be utilized in conjunction with chemotherapeutic and targeted drugs to inhibit cancer progression and improve the quality of patient survival. Therefore, doxycycline, minocycline, and tigecycline are taken as examples in this work. Their mechanisms of action in different cancers and related combination therapies are introduced. Their current roles in alleviating the suffering of patients undergoing chemotherapy when used as adjuvant drugs in clinical treatment are also described. Finally, the research gaps and potential research directions at this stage are briefly summarized.

Superparamagnetic iron oxide nanoparticles target BxPC-3 cells and silence MUC4 for theranostics of pancreatic cancer

PURPOSE

Superparamagnetic iron oxide nanoparticles (SPION) are excellent magnetic resonance imaging (MRI) contrast agents. Mucin 4 (MUC4) acts as pancreatic cancer (PC) tumor antigen and influences PC progression. Small interfering RNAs (siRNAs) are used as a gene-silencing tool to treat a variety of diseases.

METHODS

We designed a therapeutic probe based on polyetherimide-superparamagnetic iron oxide nanoparticles (PEI-SPION) combined with siRNA nanoprobes (PEI-SPION-siRNA) to assess the contrast in MRI. The biocompatibility of the nanocomposite, and silencing of MUC4 were characterized and evaluated.

RESULTS

The prepared molecular probe had a particle size of 61.7 ± 18.5 nmand a surface of 46.7 ± 0.8mVand showed good biocompatibility in vitro and T2 relaxation efficiency. It can also load and protect siRNA. PEI-SPION-siRNA showed a good silencing effect on MUC4.

CONCLUSION

PEI-SPION-siRNA may be beneficial as a novel theranostic tool for PC.

Pathological Implications of Mucin Signaling in Metastasis

The dynamic mucosal layer provides a selective protective barrier for the epithelial cells lining the body cavities. Diverse human malignancies exploit their intrinsic role to protect and repair epithelia for promoting growth and survival. Aberrant expression of mucin has been known to be associated with poor prognosis of many cancers. However, the emergence of new paradigms in the study of metastasis recognizes the involvement of MUC1, MUC4, MUC5AC, MUC5B, and MUC16 during metastasis initiation and progression. Hence mucins can be used as an attractive target in future diagnostic and therapeutic strategies. In this review, we discuss in detail about mucin family and its domains and the role of different mucins in regulating cancer progression and metastasis. In addition, we briefly discuss insights into mucins as a therapeutic agent.

Altered glycosylation in pancreatic cancer and beyond

Pancreatic ductal adenocarcinoma (PDA) is one of the deadliest cancers and is projected to soon be the second leading cause of cancer death. Median survival of PDA patients is 6-10 mo, with the majority of diagnoses occurring at later, metastatic stages that are refractory to treatment and accompanied by worsening prognoses. Glycosylation is one of the most common types of post-translational modifications. The complex landscape of glycosylation produces an extensive repertoire of glycan moieties, glycoproteins, and glycolipids, thus adding a dynamic and tunable level of intra- and intercellular signaling regulation. Aberrant glycosylation is a feature of cancer progression and influences a broad range of signaling pathways to promote disease onset and progression. However, despite being so common, the functional consequences of altered glycosylation and their potential as therapeutic targets remain poorly understood and vastly understudied in the context of PDA. In this review, the functionality of glycans as they contribute to hallmarks of PDA are highlighted as active regulators of disease onset, tumor progression, metastatic capability, therapeutic resistance, and remodeling of the tumor immune microenvironment. A deeper understanding of the functional consequences of altered glycosylation will facilitate future hypothesis-driven studies and identify novel therapeutic strategies in PDA.

Differences in gene expression despite identical histomorphology in sinonasal intestinal-type adenocarcinoma and metastases from colorectal adenocarcinoma

Sinonasal intestinal-type adenocarcinoma (sITAC) is histomorphologically indistinguishable from colorectal adenocarcinoma (CRC) leading to diagnostic challenges. Metastases from CRCs to the sinonasal tract have been reported. The aim of the study was to identify a biomarker making it possible to distinguish between sITAC and metastases of colorectal origin. Formalin-fixated paraffin-embedded (FFPE) tissue from 20 consecutive patients with sITAC treated at Rigshospitalet, Denmark from 2005 to 2017, 20 patients with CRC, and second patients with both sinonasal and colorectal carcinomas were included, and RNA-sequencing was performed on all samples. Moreover, a series of 26 samples from metastasizing CRC were included (in-house data). 3139 differentially expressed genes were identified, of these several were deemed as possible biomarkers, including CSDE1, for which immunohistochemical staining was performed. sITAC and CRC differ in genomic expression. CSDE1, previously found upregulated in CRC, was significantly differentially expressed. Using immunohistochemical staining, no sITACs displayed strong and diffuse staining for CSDE1, which represents a potential marker to use in distinguishing sITAC from a metastasis of colorectal origin. This knowledge could improve the diagnostic process and hopefully the outcome in patients with this rare tumor.

HKG: an open genetic variant database of 205 Hong Kong cantonese exomes

HKG is the first fully accessible variant database for Hong Kong Cantonese, constructed from 205 novel whole-exome sequencing data. There has long been a research gap in the understanding of the genetic architecture of southern Chinese subgroups, including Hong Kong Cantonese. HKG detected 196 325 high-quality variants with 5.93% being novel, and 25 472 variants were found to be unique in HKG compared to three Chinese populations sampled from 1000 Genomes (CHN). PCA illustrates the uniqueness of HKG in CHN, and the admixture study estimated the ancestral composition of HKG and CHN, with a gradient change from north to south, consistent with their geological distribution. ClinVar, CIViC and PharmGKB annotated 599 clinically significant variants and 360 putative loss-of-function variants, substantiating our understanding of population characteristics for future medical development. Among the novel variants, 96.57% were singleton and 6.85% were of high impact. With a good representation of Hong Kong Cantonese, we demonstrated better variant imputation using reference with the addition of HKG data, thus successfully filling the data gap in southern Chinese to facilitate the regional and global development of population genetics.

Krüppel-like transcription factor 16 transcriptional up-regulation of cellular retinoic acid-binding proteins-2 promotes the invasion and migration and inhibits apoptosis of retinoblastoma cells by regulating integrin-β1/focal adhesion kinase /extracellular signal-regulated kinase pathway

As a common intraocular malignancy in pediatrics, retinoblastoma (RB) has high prevalence worldwide. We conducted this study, aiming to explore the molecular mechanism of Krüppel-like transcription factor 16 (KLF16)/cellular retinoic acid-binding proteins-2 (CRABP2) in regulating the invasion and migration and apoptosis of RB cells via integrin-β1/focal adhesion kinase (FAK)/extracellular signal-regulated kinase (ERK) pathway. With the adoption of real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot, the mRNA and protein expression of CRABP2 and KLF16 were measured. In addition, the proliferation, clone formation ability and migration were detected with methyl thiazolyl tetrazolium (MTT), clone formation and wound healing assays, respectively. Furthermore, the invasion and apoptosis of transfected WERI-RB1 cells were evaluated with transwell and Tunel assays. With the application of Western blot, the expressions of proliferation-, apoptosis- and pathway-related proteins were assayed. The combination of KLF16 and CRABP2 was confirmed by dual-luciferase reporter assay and chromatin immunoprecipitation (ChIP). In this study, we found that CRABP2 gained a huge growth in RB cells and its silence promoted apoptosis but suppressed the proliferation, migration and invasiveness of WERI-RB1 cells. In addition, KLF16 could bind to CRABP2. It was also found that KLF16 overexpression reversed the effects of CRABP2 silence on the proliferation, migration and apoptosis of WERI-RB1 cells. What is more, CRABP2 silence blocked integrin-β1/FAK/ERK signaling pathway. In conclusion, KLF16 transcriptional up-regulation of CRABP2 promoted proliferation, invasion and migration but inhibited apoptosis of RB cells by activating integrin-β1/FAK/ERK pathway.

Mucin Expression and Splicing Determine Novel Subtypes and Patient Mortality in Pancreatic Ductal Adenocarcinoma

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy demonstrating aberrant and progressive expression of mucins. The contribution of individual mucins has been extensively investigated in PDAC; however, comprehensive mucin profiling including splice variants in PDAC tumors has not been reported.

EXPERIMENTAL DESIGN

Using publicly available RNA sequencing (RNA-seq) datasets, we assess the expression of mucin family members and their splice variants (SV) in PDAC tumor samples for the first time. Mucin SVs that are correlated with PDAC patient survival are validated in a cohort of patient tumor samples. Further, we use computational methods to derive novel pancreatic tumor subtypes using mucin expression signatures and their associated activated pathways.

RESULTS

Principal component analysis identified four novel mucin-based PDAC subtypes. Pathway analysis implicated specific biological signatures for each subtype, labeled (i) immune activated, (ii) progressive, (iii) pancreatitis-initiated, and (iv) anti-inflammatory/PanIN-initiated. Assessing mucin SVs, significantly longer survival is observed with higher expression of 4 MUC1 and 1 MUC13 SVs, whereas patients expressing 2 MUC4 and 1 MUC16 SVs had shorter survival. Using a whole-transcriptome correlation, a three-gene panel, including ESRP2, PTK6, and MAGEH1, is designated to assess PDAC tumor sample cellularity by PCR. One MUC4 SV and one MUC13 SV are quantified in a separate PDAC patient cohort, and their effects on survival are experimentally validated.

CONCLUSIONS

Altogether, we demonstrate the unique expression pattern of mucins, four mucin-based PDAC subtypes, and the contribution of MUC1, MUC4, and MUC16 SVs in PDAC patient survival.

Signature of gene aberrant alternative splicing events in pancreatic adenocarcinoma prognosis

Alternative splicing (AS), as an effective and universal mechanism of transcriptional regulation, is involved in the development and progression of cancer. Therefore, systematic analysis of alternative splicing in pancreatic adenocarcinoma (PAAD) is warranted. The corresponding clinical information of the RNA-Seq data and PAAD cohort was downloaded from the TCGA data portal. Then, a java application, SpliceSeq, was used to evaluate the RNA splicing pattern and calculate the splicing percentage index (PSI). Differentially expressed AS events (DEAS) were identified based on PSI values between PAAD cancer samples and normal samples of adjacent tissues. Kaplan-Meier and Cox regression analyses were used to assess the association between DEAS and patient clinical characteristics. Unsupervised cluster analysis used to reveal four clusters with different survival patterns. At the same time, GEO and TCGA combined with GTEx to verify the differential expression of AS gene and splicing factor. After rigorous filtering, a total of 45,313 AS events were identified, 1,546 of which were differentially expressed AS events. Nineteen DEAS were found to be associated with OS with a five-year overall survival rate of 0.946. And the subtype clusters results indicate that there are differences in the nature of individual AS that affect clinical outcomes. Results also identified 15 splicing factors associated with the prognosis of PAAD. And the splicing factors ESRP1 and RBM5 played an important role in the PAAD-associated AS events. The PAAD-associated AS events, splicing networks, and clusters identified in this study are valuable for deciphering the underlying mechanisms of AS in PAAD and may facilitate the establishment of therapeutic goals for further validation.

Unraveling mucin domains in cancer and metastasis: when protectors become predators

A dynamic mucosal layer shields the epithelial cells lining the body cavities and is made up of high molecular weight, heavily glycosylated, multidomain proteins called mucins. Mucins, broadly grouped into transmembrane and secreted mucins, are the first responders to any mechanical or chemical insult to the epithelia and help maintain tissue homeostasis. However, their intrinsic properties to protect and repair the epithelia are exploited during oncogenic processes, where mucins are metamorphosed to aid the tumor cells in their malignant journey. Diverse domains, like the variable number tandem repeats (VNTR), sea urchin sperm protein enterokinase and agrin (SEA), adhesion-associated domain (AMOP), nidogen-like domain (NIDO), epidermal growth factor-like domain (EGF), and von Willebrand factor type D domain (vWD) on mucins, including MUC1, MUC4, MUC5AC, MUC5B, and MUC16, have been shown to facilitate cell-to-cell and cell-to-matrix interactions, and cell-autonomous signaling to promote tumorigenesis and distant dissemination of tumor cells. Several obstacles have limited the study of mucins, including technical difficulties in working with these huge glycoproteins, the dearth of scientific tools, and lack of animal models; thus, the tissue-dependent and domain-specific roles of mucins during mucosal protection, chronic inflammation, tumorigenesis, and hematological dissemination of malignant cells are still unclear. Future studies should try to integrate information on the rheological, molecular, and biological characteristics of mucins to comprehensively delineate their pathophysiological role and evaluate their suitability as targets in future diagnostic and therapeutic strategies.

MUC4 is a novel mediator in H. pylori infection-related pancreatic cancer

Pancreatic cancer (PC) is a common malignant disease worldwide. Among the potential pathogenic factors, Helicobacter pylori (H. pylori) infection has been associated with the tumorigenesis of PC. The present study aimed to identify the differentially expressed genes (DEGs) of H. pylori infection-associated PC and to investigate the key factors involved in PC tumorigenesis. Using bioinformatics methods, overlapping DEGs and key gene were identified from H. pylori-infected gastric mucosa (GM) and H. pylori infection-associated PC. Survival and tumor stage analyses were performed to assess the clinical associations. In addition, mucin 4 (MUC4) mRNA expression levels were measured in patient blood and tumor samples. According to the correlation analyses of four genes co-expressed, potential biological processes were identified. MUC4 was identified to be associated with H. pylori infection, and its levels were significantly upregulated in PC samples compared with those in normal samples in TCGA dataset, the PC cell line and patient tissue samples. H. pylori infection was also associated with MUC4 expression in patients' blood and tissue samples. In conclusion, the results of the present study revealed a potentially pathogenic role of MUC4 in H. pylori infection-associated PC. Thus, the tumorigenesis and metastasis of PC may be prevented by treating the H. pylori infection or using MUC4 antagonists.

Microenvironment remodeled by tumor and stromal cells elevates fibroblast-derived COL1A1 and facilitates ovarian cancer metastasis

Wide peritoneal metastasis is the cause of the highest lethality of ovarian cancer in gynecologic malignancies. Ascites play a key role in ovarian cancer metastasis, but involved mechanism is uncertain. Here, we performed a quantitative proteomics of ascites, and found that collagen type I alpha 1 (COL1A1) was notably elevated in ascites from epithelial ovarian cancer patients compared to normal peritoneal fluids, and verified that elevated COL1A1 was mainly originated from fibroblasts. COL1A1 promoted migration and invasion of ovarian cancer cells, but such effects were partially eliminated by COL1A1 antibodies. Intraperitoneally injected COL1A1 accelerated intraperitoneal metastasis of ovarian cancer xenograft in NOD/SCID mice. Further, COL1A1 activated downstream AKT phosphorylation by binding to membrane surface receptor integrin β1 (ITGB1). Knockdown or blockage of ITGB1 reversed COL1A1 enhanced migration and invasion in ovarian cancer cells. Conversely, ovarian cancer ascites and fibrinogen promoted fibroblasts to secrete COL1A1. Elevated fibrinogen in ascites might be associated with increased vascular permeability induced by ovarian cancer. Our findings suggest that microenvironment remodeled by tumor cells and stromal cells promotes fibroblasts to secrete COL1A1 and facilitates the metastasis of ovarian cancer, which may provide a new approach for ovarian cancer therapeutics.

Effect of magnesium ions/Type I collagen promote the biological behavior of osteoblasts and its mechanism

Type I collagen (Col I) is a main component of extracellular matrix (ECM). Its safety, biocompatibility, hydrophilicity and pyrogen immunogenicity make it suitable for tissues engineering applications. Mg²⁺ also control a myriad of cellular processes, including the bone development by enhancing the attachment and differentiation of osteoblasts and accelerating mineralization to enhance bone healing. In our studies, Mg²⁺ bind collagen to promote the proliferation and differentiation of osteoblasts through the expression of integrins and downstream signaling pathways. In order to clarify the biological behavior effect of 10 mM Mg²⁺/Col I coating, we performed 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), alkaline phosphatase (ALP), 4′6-diamidino-2-phenylindole (DAPI), Alizarin red staining and Rhodamine B-isothiocyanate (RITC)-labeled phalloidin experiments and found that 10 mM Mg²⁺ group, Col I-coating group, 10 mM Mg²⁺/Col I-coating group, respectively, promoted the proliferation and differentiation of osteoblasts, especially 10 mM Mg²⁺/Col I-coating group. We detected the mRNA expression of osteogenic-related genes (Runx2, ALP and OCN, OPN and BMP-2) and the protein expression of signaling pathway (integrin α2, integrin β1, FAK and ERK1/2), these results indicated that 10 mM Mg²⁺/Col I coating play an critical role in up-regulating the MC3T3-E1 cells activity. The potential mechanisms of this specific performance may be through activating via integrin α2β1-FAK-ERK1/2 protein-coupled receptor pathway.

MUC4 isoforms expression profiling and prognosis value in Chinese melanoma patients

Mucin 4 (MUC4), a type I membrane-bound mucin, blocks apoptosis, promotes invasion, proliferation and migration and causes chemo-resistance in epithelial cancers. However, the expression profiling and clinical implications of MUC4 alternative splicing during cancer pathogenesis, including melanoma, remain obscure. We examined the mRNA expression profiling of MUC4 isoforms in gastrointestinal cancer cell lines, melanoma cell lines, human epidermal melanocyte cells, as well as 138 cases of human melanoma tissues by RT-qPCR. Then we analyzed the relationship of mRNA expression of MUC4 isoforms to clinicopathological characteristics and survival of patients. The dynamic mRNA expression profiling of MUC4 isoforms was found in melanoma. We identified MUC4 isoform f was highly expressed in melanoma cell lines but negative in gastrointestinal cancer cell lines. Clinical analysis based on 138 cases of human melanomas showed that MUC4 isoform d was related with melanoma subtypes (p = 0.028) and TNM stage (p = 0.036). MUC4 isoform e was related with tumor thickness (p = 0.004) and T stage (p = 0.036). The Kaplan-Meier assay showed that the median overall survival (OS) for patients with MUC4 isoform f high expression was significantly shorter than that of patients with low expression (p = 0.024). And the median PFS of the patients with high expression of MUC4 isoform d or e was significantly shorter than that of with low expression (p = 0.012 and 0.035, respectively). Multivariate analysis indicated that high level of MUC4 isoform f was an independent prognostic factor for OS, and MUC4 isoform d was an independent prognostic factor for PFS of patients treated with chemotherapy. In conclusion, our results indicate that the dynamic MUC4 isoforms expressed in melanoma, and MUC4 isoform d and f might be served as a novel prognostic indicator of melanoma patients.

Mucin glycoproteins block apoptosis; promote invasion, proliferation, and migration; and cause chemoresistance through diverse pathways in epithelial cancers

Overexpression of mucin glycoproteins has been demonstrated in many epithelial-derived cancers. The significance of this overexpression remains uncertain. The aim of this paper was to define the association of mucin glycoproteins with apoptosis, cell growth, invasion, migration, adhesion, and clonogenicity in vitro as well as tumor growth, tumorigenicity, and metastasis in vivo in epithelial-derived cancers by performing a systematic review of all published data. A systematic review of PubMed, Embase, and the Cochrane Central Register of Controlled Trials was performed to identify all papers that evaluated the association between mucin glycoproteins with apoptosis, cell growth, invasion, migration, adhesion, and clonogenicity in vitro as well as tumor growth, tumorigenicity, and metastasis in vivo in epithelial-derived cancers. PRISMA guidelines were adhered to. Results of individual studies were extracted and pooled together based on the organ in which the cancer was derived from. The initial search revealed 2031 papers, of which 90 were deemed eligible for inclusion in the study. The studies included details on MUC1, MUC2, MUC4, MUC5AC, MUC5B, MUC13, and MUC16. The majority of studies evaluated MUC1. MUC1 overexpression was consistently associated with resistance to apoptosis and resistance to chemotherapy. There was also evidence that overexpression of MUC2, MUC4, MUC5AC, MUC5B, MUC13, and MUC16 conferred resistance to apoptosis in epithelial-derived cancers. The overexpression of mucin glycoproteins is associated with resistance to apoptosis in numerous epithelial cancers. They cause resistance through diverse signaling pathways. Targeting the expression of mucin glycoproteins represents a potential therapeutic target in the treatment of epithelial-derived cancers.

MUCIN-4 (MUC4) is a novel tumor antigen in pancreatic cancer immunotherapy

Pancreatic cancer (PC) is a highly lethal malignancy with a dismal five-year survival rate. This is due to its asymptomatic nature, lack of reliable biomarkers, poor resectability, early metastasis, and high recurrence rate. Limited efficacies of current treatment modalities treatment-associated toxicity underscore the need for the development of immunotherapy-based approaches. For non-resectable, locally advanced metastatic PC, immunotherapy-based approaches including vaccines, antibody-targeted, immune checkpoint inhibition, CAR-T-cells, and adoptive T-cell transfer could be valuable additions to existing treatment modalities. Thus far, the vaccine candidates in PC have demonstrated modest immunological responses in different treatment modalities. The identification of tumor-associated antigens (TAA) and their successful implication in PC treatment is still a challenge. MUC4, a high molecular weight glycoprotein that functionally contributes to PC pathogenesis, is an attractive TAA. It is not detected in the normal pancreas; however, it is overexpressed in mouse and human pancreatic tumors. The recombinant MUC4 domain, as well as predicted immunogenic T-cell epitopes, elicited cellular and humoral anti-MUC4 response, suggesting its ulility as a vaccine candidate for PC therapy. Existence of PC-associated MUC4 splice variants, autoantibodies against overexpressed and aberrantly glycosylated MUC4 and presence of T-cell clones against the mutations present in MUC4 further reinforce its significance as a tumor antigen for vaccine development. Herein, we review the significance of MUC4 as a tumor antigen in PC immunotherapy and discuss both, the development and challenges associated with MUC4 based immunotherapy. Lastly, we will present our perspective on MUC4 antigenicity for the future development of MUC4-based PC immunotherapy.