Muc4/MUC4 functions and regulation in cancer

A comparative analysis of alternative splicing patterns in Atlantic salmon (Salmo salar) in response to Moritella viscosa and sea lice (Lepeophtheirus salmonis) infection

Moritella viscosa (M. viscosa) and sea lice (Lepeophtheirus salmonis) are severe pathogens that primarily infect the skin of Atlantic salmon (Salmo salar), which cause significant economic losses in the farming industry. However, the pathogenesis and molecular mechanisms underlying the host's immune defence at the post-transcriptional level remain unclear. Alternative splicing (AS) is an evolutionarily conserved post-transcriptional mechanism that can greatly increase the richness of the transcriptome and proteome. In this study, transcriptomic data derived from skin tissues of Atlantic salmon after M. viscosa and sea lice infections were used to examine the AS profiles and their differential expression patterns. In total, we identified 33,044 AS events (involving 13,718 genes) in the control (CON) group, 35,147 AS events (involving 14,340 genes) in the M. viscosa infection (MV) group, and 30,364 AS events (involving 13,142 genes) in the sea lice infection (LC) group, respectively. Among the five types of AS identified in our study (i.e., SE, A5SS, A3SS, MXE, and RI), SE was the most prevalent type in all three groups (i.e., CON, MV, and LC groups). Decreased percent-spliced-in (PSI) levels were observed in SE events under both MV- and LC-infected conditions, suggesting that MV or LC infection elevated exon-skipping isoforms and promoted the selection of shorter transcripts in numerous DAS genes. In addition, most of the differential AS genes were found to be associated with pathways related to mRNA regulation, epithelial or muscle development, and immune response. These findings provide novel insights into the role of AS in host-pathogen interactions and represent the first comparative analysis of AS in response to bacterial and parasitic infections in fish.

Tn antigen interactions of macrophage galactose-type lectin (MGL) in immune function and disease

Protein-carbohydrate interactions are essential in maintaining immune homeostasis and orchestrating inflammatory and regulatory immune processes. This review elucidates the immune interactions of macrophage galactose-type lectin (MGL, CD301) and Tn carbohydrate antigen. MGL is a C-type lectin receptor (CLR) primarily expressed by myeloid cells such as macrophages and immature dendritic cells. MGL recognizes terminal O-linked N-acetylgalactosamine (GalNAc) residue on the surface proteins, also known as Tn antigen (Tn). Tn is a truncated form of the elongated cell surface O-glycan. The hypoglycosylation leading to Tn may occur when the enzyme responsible for O-glycan elongation-T-synthase-or its associated chaperone-Cosmc-becomes functionally inhibited. As reviewed here, Tn expression is observed in many different neoplastic and non-neoplastic diseases, and the recognition of Tn by MGL plays an important role in regulating effector T cells, immune suppression, and the recognition of pathogens.

Identification and validation of six acute myocardial infarction-associated variants, including a novel prognostic marker for cardiac mortality

Background

Acute myocardial infarction (AMI) is one of the leading causes of death worldwide, and approximately half of AMI-related deaths occur before the affected individual reaches the hospital. The present study aimed to identify and validate genetic variants associated with AMI and their role as prognostic markers.

Materials and methods

We conducted a replication study of 29 previously identified novel loci containing 85 genetic variants associated with early-onset AMI using a new independent set of 2,920 Koreans [88 patients with early- and 1,085 patients with late-onset AMI, who underwent percutaneous coronary intervention (PCI), and 1,747 healthy controls].

Results

Of the 85 previously reported early-onset variants, six were confirmed in our genome-wide association study with a false discovery rate of less than 0.05. Notably, rs12639023, a cis-eQTL located in the intergenic region between LINC02005 and CNTN3, significantly increased longitudinal cardiac mortality and recurrent AMI. CNTN3 is known to play a role in altering vascular permeability. Another variant, rs78631167, located upstream of PLAUR and known to function in fibrinolysis, was moderately replicated in this study. By surveying the nearby genomic region around rs78631167, we identified a significant novel locus (rs8109584) located 13 bp downstream of rs78631167. The present study showed that six of the early-onset variants of AMI are applicable to both early- and late-onset cases.

Conclusion

Our results confirm markers that can potentially be utilized to predict, screen, prevent, and treat candidate patients with AMI and highlight the potential of rs12639023 as a prognostic marker for cardiac mortality in AMI.

Proteomic analysis of brain metastatic lung adenocarcinoma reveals intertumoral heterogeneity and specific alterations associated with the timing of brain metastases

BACKGROUND

Brain metastases are associated with considerable negative effects on patients' outcome in lung adenocarcinoma (LADC). Here, we investigated the proteomic landscape of primary LADCs and their corresponding brain metastases.

MATERIALS AND METHODS

Proteomic profiling was conducted on 20 surgically resected primary and brain metastatic LADC samples via label-free shotgun proteomics. After sample processing, peptides were analyzed using an Ultimate 3000 pump coupled to a QExactive HF-X mass spectrometer. Raw data were searched using PD 2.4. Further data analyses were carried out using Perseus, RStudio and GraphPad Prism. Proteomic data were correlated with clinical and histopathological parameters and the timing of brain metastases. Mass spectrometry-based proteomic data are available via ProteomeXchange with identifier PXD027259.

RESULTS

Out of the 6821 proteins identified and quantified, 1496 proteins were differentially expressed between primary LADCs and corresponding brain metastases. Pathways associated with the immune system, cell-cell/matrix interactions and migration were predominantly activated in the primary tumors, whereas pathways related to metabolism, translation or vesicle formation were overrepresented in the metastatic tumors. When comparing fast- versus slow-progressing patients, we found 454 and 298 differentially expressed proteins in the primary tumors and brain metastases, respectively. Metabolic reprogramming and ribosomal activity were prominently up-regulated in the fast-progressing patients (versus slow-progressing individuals), whereas expression of cell-cell interaction- and immune system-related pathways was reduced in these patients and in those with multiple brain metastases.

CONCLUSIONS

This is the first comprehensive proteomic analysis of paired primary tumors and brain metastases of LADC patients. Our data suggest a malfunction of cellular attachment and an increase in ribosomal activity in LADC tissue, promoting brain metastasis. The current study provides insights into the biology of LADC brain metastases and, moreover, might contribute to the development of personalized follow-up strategies in LADC.

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.

The diagnostic and prognostic potential of the EGFR/MUC4/MMP9 axis in glioma patients

Glioblastoma is the most aggressive form of brain cancer, presenting poor prognosis despite current advances in treatment. There is therefore an urgent need for novel biomarkers and therapeutic targets. Interactions between mucin 4 (MUC4) and the epidermal growth factor receptor (EGFR) are involved in carcinogenesis, and may lead to matrix metalloproteinase-9 (MMP9) overexpression, exacerbating cancer cell invasiveness. In this study, the role of MUC4, MMP9, and EGFR in the progression and clinical outcome of glioma patients was investigated. Immunohistochemistry (IHC) and immunofluorescence (IF) in fixed tissue samples of glioma patients were used to evaluate the expression and localization of EGFR, MMP9, and MUC4. Kaplan-Meier survival analysis was also performed to test the prognostic utility of the proteins for glioma patients. The protein levels were assessed with enzyme-linked immunosorbent assay (ELISA) in serum of glioma patients, to further investigate their potential as non-invasive serum biomarkers. We demonstrated that MUC4 and MMP9 are both significantly upregulated during glioma progression. Moreover, MUC4 is co-expressed with MMP9 and EGFR in the proliferative microvasculature of glioblastoma, suggesting a potential role for MUC4 in microvascular proliferation and angiogenesis. The combined high expression of MUC4/MMP9, and MUC4/MMP9/EGFR was associated with poor overall survival (OS). Finally, MMP9 mean protein level was significantly higher in the serum of glioblastoma compared with grade III glioma patients, whereas MUC4 mean protein level was minimally elevated in higher glioma grades (III and IV) compared with control. Our results suggest that MUC4, along with MMP9, might account for glioblastoma progression, representing potential therapeutic targets, and suggesting the 'MUC4/MMP9/EGFR axis' may play a vital role in glioblastoma diagnostics.

Esophageal Squamous Cancer from 4NQO-Induced Mice Model: CNV Alterations

Squamous esophageal carcinoma is a common pathological type of esophageal carcinoma around the world. The prognosis of esophageal carcinoma is usually poor and diagnosed at late stages. Recently, research suggested that genomic instability occurred in esophageal cells during the development of esophageal squamous cell carcinoma (ESCC). Identifying prognostic and specific genomic characteristics, especially at the early hyperplasia stage, is critical. Mice were given 4-nitroquinoline 1-oxide (4NQO) with drinking water to induce esophageal cancer. The immortalized human esophageal epithelial cell line (NE2) was also treated with 4NQO. We performed histologic analyses, immunofluorescence, and immunohistochemical staining to detect DNA damage at different time points. Whole-exome sequencing was accomplished on the esophagus tissues at different pathological stages to detect single-nucleotide variants and copy number variation (CNV) in the genome. Our findings indicate that all mice were tumor-forming, and a series of changes from simple hyperplasia (ESSH) to intraepithelial neoplasia (IEN) to esophageal squamous cell carcinoma (ESCC) was seen at different times. The expression of γ-H2AX increased from ESSH to ESCC. In addition, mutations of the Muc4 gene were detected throughout the pathological stages. Furthermore, CNV burden appeared in the esophageal tissues from the beginning of ESSH and accumulated more in cancer with the deepening of the lesions. This study demonstrates that mutations caused by the early appearance of DNA damage may appear in the early stage of malignant tissue before the emergence of atypia. The detection of CNV and mutations of the Muc4 gene may be used as an ultra-early screening indicator for esophageal cancer.

Viral Integration Plays a Minor Role in the Development and Prognostication of Oral Squamous Cell Carcinoma

Viruses are well known drivers of several human malignancies. A causative factor for oral cavity squamous cell carcinoma (OSCC) in patients with limited exposure to traditional risk factors, including tobacco use, is yet to be identified. Our study aimed to comprehensively evaluate the role of viral drivers in OSCC patients with low cumulative exposure to traditional risk factors. Patients under 50 years of age with OSCC, defined using strict anatomic criteria were selected for WGS. The WGS data was interrogated using viral detection tools (Kraken 2 and BLASTN), together examining >700,000 viruses. The findings were further verified using tissue microarrays of OSCC samples using both immunohistochemistry and RNA in situ hybridisation (ISH). 28 patients underwent WGS and comprehensive viral profiling. One 49-year-old male patient with OSCC of the hard palate demonstrated HPV35 integration. 657 cases of OSCC were then evaluated for the presence of HPV integration through immunohistochemistry for p16 and HPV RNA ISH. HPV integration was seen in 8 (1.2%) patients, all middle-aged men with predominant floor of mouth involvement. In summary, a wide-ranging interrogation of >700,000 viruses using OSCC WGS data showed HPV integration in a minority of male OSCC patients and did not carry any prognostic significance.

Uncovering emergent phenotypes in endothelial cells by clustering of surrogates of cardiovascular risk factors

Endothelial dysfunction (ED) is a hallmark of atherosclerosis and is influenced by well-defined risk factors, including hypoxia, dyslipidemia, inflammation, and oscillatory flow. However, the individual and combined contributions to the molecular underpinnings of ED remain elusive. We used global gene expression in human coronary artery endothelial cells to identify gene pathways and cellular processes in response to chemical hypoxia, oxidized lipids, IL-1β induced inflammation, oscillatory flow, and these combined stimuli. We found that clustering of the surrogate risk factors differed from the sum of the individual insults that gave rise to emergent phenotypes such as cell proliferation. We validated these observations in samples of human coronary artery atherosclerotic plaques analyzed using single-cell RNA sequencing. Our findings suggest a hierarchical interaction between surrogates of CV risk factors and the advent of emergent phenotypes in response to combined stimulation in endothelial cells that may influence ED.

Characterization of recombinant β subunit of human MUC4 mucin (rMUC4β)

MUC4 is a transmembrane mucin expressed on various epithelial surfaces, including respiratory and gastrointestinal tracts, and helps in their lubrication and protection. MUC4 is also aberrantly overexpressed in various epithelial malignancies and functionally contributes to cancer development and progression. MUC4 is putatively cleaved at the GDPH site into a mucin-like α-subunit and a membrane-tethered growth factor-like β-subunit. Due to the presence of several functional domains, the characterization of MUC4β is critical for understanding MUC4 biology. We developed a method to produce and purify multi-milligram amounts of recombinant MUC4β (rMUC4β). Purified rMUC4β was characterized by Far-UV CD and I-TASSER-based protein structure prediction analyses, and its ability to interact with cellular proteins was determined by the affinity pull-down assay. Two of the three EGF-like domains exhibited typical β-fold, while the third EGF-like domain and vWD domain were predominantly random coils. We observed that rMUC4β physically interacts with Ezrin and EGFR family members. Overall, this study describes an efficient and simple strategy for the purification of biologically-active rMUC4β that can serve as a valuable reagent for a variety of biochemical and functional studies to elucidate MUC4 function and generating domain-specific antibodies and vaccines for cancer immunotherapy.

The Development of Vaccines from Synthetic Tumor-Associated Mucin Glycopeptides and their Glycosylation-Dependent Immune Response

Tumor-associated carbohydrate antigens are overexpressed as altered-self in most common epithelial cancers. Their glycosylation patterns differ from those of healthy cells, functioning as an ID for cancer cells. Scientists have been developing anti-cancer vaccines based on mucin glycopeptides, yet the interplay of delivery system, adjuvant and tumor associated MUC epitopes in the induced immune response is not well understood. The current state of the art suggests that the identity, abundancy and location of the glycans on the MUC backbone are all key parameters in the cellular and humoral response. This review shares lessons learned by us in over two decades of research in glycopeptide vaccines. By bridging synthetic chemistry and immunology, we discuss efforts in designing synthetic MUC1/4/16 vaccines and focus on the role of glycosylation patterns. We provide a brief introduction into the mechanisms of the immune system and aim to promote the development of cancer subunit vaccines.

The EGF Domains of MUC4 Oncomucin Mediate HER2 Binding Affinity and Promote Pancreatic Cancer Cell Tumorigenesis

Simple Summary

A feature of pancreatic cancer (PC) is the frequent overexpression of tyrosine kinase membrane receptor HER2 along with its membrane partner the MUC4 oncomucin in the early stages of the pancreatic carcinogenesis. However, therapeutic approaches targeting HER2 in PC are not efficient. MUC4 could indeed represent an alternative therapeutic strategy to target HER2 signaling pathway, but this approach needs to characterize MUC4/HER2 interaction at the molecular level. In this study, we successfully showed the impact of the EGF domains of MUC4 on HER2 binding affinity and demonstrated their “growth factor-like” biological activities in PC cells. Moreover, homology models of the MUC4_EGF/HER2 complexes allowed identification of binding hotspots mediating binding affinity with HER2 and PC cell proliferation. These results allow a better understanding of the mechanisms involved in the MUC4/HER2 complex formation and may lead to the design of potential MUC4/HER2 inhibitors.

Abstract

The HER2 receptor and its MUC4 mucin partner form an oncogenic complex via an extracellular region of MUC4 encompassing three EGF domains that promotes tumor progression of pancreatic cancer (PC) cells. However, the molecular mechanism of interaction remains poorly understood. Herein, we decipher at the molecular level the role and impact of the MUC4_EGF domains in the mediation of the binding affinities with HER2 and the PC cell tumorigenicity. We used an integrative approach combining in vitro bioinformatic, biophysical, biochemical, and biological approaches, as well as an in vivo study on a xenograft model of PC. In this study, we specified the binding mode of MUC4_EGF domains with HER2 and demonstrate their “growth factor-like” biological activities in PC cells leading to stimulation of several signaling proteins (mTOR pathway, Akt, and β-catenin) contributing to PC progression. Molecular dynamics simulations of the MUC4_EGF/HER2 complexes led to 3D homology models and identification of binding hotspots mediating binding affinity with HER2 and PC cell proliferation. These results will pave the way to the design of potential MUC4/HER2 inhibitors targeting the EGF domains of MUC4. This strategy will represent a new efficient alternative to treat cancers associated with MUC4/HER2 overexpression and HER2-targeted therapy failure as a new adapted treatment to patients.

Case Report: Effective Treatment With Pyrotinib and Capecitabine in a Heavily Pretreated Locally Advanced Breast Cancer Harboring Both HER2 Overexpression and Mutant

The prognosis for female patients with locally advanced breast cancer (LABC) has improved with the emergence of novel drugs, especially for those who have HER2 overexpression or ERBB-2 amplification. Trastuzumab-based regimen has been the paradigm in guidelines as first-line therapy, whereas many patients got progressive disease after several cycles of treatment or rapidly progress because of primary resistance. Point mutations of ERBB2 gene occur in both HER2-amplication and non-amplification patients, with a 2% ratio in HER2 non-amplification cohort and 1.48% in HER2 amplication population. The acquired mutation ratio of ERBB2 substantially raised to 16.7%–17.7% in patients prior to trastuzumab treatment. ERBB2 mutation may be a critical reason of resistance and disease progression among the patients treated with anti-HER2 monoclonal trastuzumab or dual anti-HER2 antibodies with trastuzumab and pertuzumab, or tyrosine-kinase inhibitor. ERBB-2 mutation with L755S and V842I indicates resistance to trastuzumab, while that with L755S and K753I indicates resistance to lapatinib; these mutations maybe sensitive to pan-HER tyrosine-kinase inhibitors. A 48-year woman diagnosed with HER2-positive LABC developed trastuzumab resistance after three lines of trastuzumab cross-line treatment with partial response (PR) as the best response. The tissue was performed by next-generation sequencing (NGS), and the results discovered L755S in ERBB2 gene. Then, she received effective treatment with pyrotinib plus capecitabine and underwent mastectomy after six cycles of combined treatment with PR. Subsequently, breast mastectomy was performed, and she took pyrotinib plus capecitabine for 1 year and pyrotinib monotherapy for another 1 year as adjuvant therapy and achieved a long-term clinical benefit. In conclusion, pyrotinib is a potential neoadjuvant agent for patients who are heavily pretreated and harbor both ERBB2 amplification and ERBB2 mutant in locally advanced breast cancer.

Mucin 20 modulates proteasome capacity through c-Met signalling to increase carfilzomib sensitivity in mantle cell lymphoma

Mantle cell lymphoma (MCL) is a haematologic malignancy. The proteasome inhibitor (PI) bortezomib has been approved to treat MCL, but resistance has emerged through mechanisms that remain unclear. This study aimed to explore the mechanism of PI resistance in MCL and identify new targets for this patient subgroup. Carfilzomib‐resistant (CR) MCL cell lines and primary samples were used for both in vitro and in vivo experiments to identify gene expression and explore their related signalling pathways. We first identified mucin 20 (MUC20) suppression in carfilzomib‐resistant MCL models. MUC20 overexpression sensitized cells to carfilzomib in vitro and in vivo. MUC20 expression was inversely related to activation of c‐Met and the downstream p44/42 MAPK pathway. c‐Met activation with hepatocyte growth factor (HGF) induced PI resistance, while c‐Met inhibition restored PI sensitivity. Carfilzomib resistance and depressed MUC20 expression were associated with enhanced proteasome activity and higher expression of proteassemblin (POMP), a chaperone for catalytically active proteasome assembly. c‐Met and POMP were associated through binding and induction of MAPK‐regulated ELK1 to the POMP promoter. Our data reveal that c‐Met signalling activation enhanced proteasome capacity as a mechanism of PI resistance, and MUC20 expression may be a useful biomarker for PI therapy.

The combination of dextran sulphate and polyvinyl alcohol prevents excess aggregation and promotes proliferation of pluripotent stem cells in suspension culture

OBJECTIVES

For clinical applications of cell-based therapies, a large quantity of human pluripotent stem cells (hPSCs) produced in standardized and scalable culture processes is required. Currently, microcarrier-free suspension culture shows potential for large-scale expansion of hPSCs; however, hPSCs tend to aggregate during culturing leading to a negative effect on cell yield. To overcome this problem, we developed a novel protocol to effectively control the sizes of cell aggregates and enhance the cell proliferation during the expansion of hPSCs in suspension.

MATERIALS AND METHODS

hPSCs were expanded in suspension culture supplemented with polyvinyl alcohol (PVA) and dextran sulphate (DS), and 3D suspension culture of hPSCs formed cell aggregates under static or dynamic conditions. The sizes of cell aggregates and the cell proliferation as well as the pluripotency of hPSCs after expansion were assessed using cell counting, size analysis, real-time quantitative polymerase chain reaction, flow cytometry analysis, immunofluorescence staining, embryoid body formation, teratoma formation and transcriptome sequencing.

RESULTS

Our results demonstrated that the addition of DS alone effectively prevented hPSC aggregation, while the addition of PVA significantly enhanced hPSC proliferation. The combination of PVA and DS not only promoted cell proliferation of hPSCs but also produced uniform and size-controlled cell aggregates. Moreover, hPSCs treated with PVA, or DS or a combination, maintained the pluripotency and were capable of differentiating into all three germ layers. mRNA-seq analysis demonstrated that the combination of PVA and DS significantly promoted hPSC proliferation and prevented cell aggregation through improving energy metabolism-related processes, regulating cell growth, cell proliferation and cell division, as well as reducing the adhesion among hPSC aggregates by affecting expression of genes related to cell adhesion.

CONCLUSIONS

Our results represent a significant step towards developing a simple and robust approach for the expansion of hPSCs in large scale.

Integrative Analysis of MUC4 to Prognosis and Immune Infiltration in Pan-Cancer: Friend or Foe?

MUC4, a transmembrane mucin, plays important roles in epithelial renewal and differentiation. Recent studies suggest that MUC4 has been implicated in pancreatic cancer pathogenesis and is expressed in various normal and cancer tissues. The underlying features of MUC4 across various cancer types may allow us to ensure appropriate treatment and patient monitoring. However, the contributions of MUC4 to pan-cancer have not been well characterized. In this study, we investigated the expression pattern and prognostic value of MUC4 across multiple databases. We further explored genomic and epigenetic alterations of MUC4, its association with proliferation and metastasis, and the correlation with immune infiltration in different cancers. Our results characterized the distinct expression profile and prognostic values of MUC4 in pan-cancer. Through examining its association with genomic alteration, tumor proliferation, and metastasis, as well as tumor infiltration, we revealed multiple function effects of MUC4. MUC4 may influence prognosis, proliferation, metastasis, and immune response in opposite directions. In conclusion, our findings suggested the necessity to more carefully evaluate MUC4 as a biomarker and therapeutic target and develop the new antibodies for cancer detection and intervention.

Clinicopathological characteristics and prognosis of signet ring cell carcinoma of the gallbladder

Background

Signet ring cell carcinoma (SRC) is a rare histological subtype of gallbladder adenocarcinoma. The current study evaluates the clinicopathologic features and prognosis of SRC.

Methods

Patients with adenocarcinoma of the gallbladder were identified in the Surveillance, Epidemiology, and End Results database from 1973 to 2016. Overall survival (OS) and cancer-specific survival (CSS) of patients who had SRC were compared with those of patients who had non-SRC using Cox regression and propensity score methods.

Results

Of 22,781 gallbladder adenocarcinomas retrieved, 377 (1.7%) were SRC and the other 22,404 were non-SRC. SRC was more significantly associated with older age, female gender, poor differentiation, advanced tumor stage, lymph node metastasis, distant metastasis, and advanced AJCC stage. The 5-year OS and CSS in the SRC group were 7.2 and 6.5%, respectively, both of which were significantly worse than the 13.2 and 13.3% seen in the SRC group (P = 0.002 and P = 0.012, respectively). This survival disadvantage persisted in multivariable analyses [hazard ratio (HR) = 1.256, P = 0.021 and HR = 1.211, P = 0.036] and after propensity score matching (OS: HR = 1.341, P = 0.012 and CSS: HR = 1.625, P = 0.005). Surgery in combination with chemotherapy improved OS of gallbladder SRC patients compared with surgery alone (HR = 0.726, P = 0.036) or chemotherapy alone (HR = 0.433, P < 0.001).

Conclusion

Patients with SRC of the gallbladder have distinct clinicopathological features with poor prognosis. Surgery in combination with chemotherapy can improve survival.

MUC4 enhances gemcitabine resistance and malignant behaviour in pancreatic cancer cells expressing cancer-associated short O-glycans

Pancreatic ductal adenocarcinoma (PDAC) is highly lethal. MUC4 (mucin4) is a heavily glycosylated protein aberrantly expressed in PDAC and promotes tumorigenesis via an unknown mechanism. To assess this, we genetically knocked out (KO) MUC4 in PDAC cells that did not express and did express truncated O-glycans (Tn/STn) using CRISPR/Cas9 technology. We found that MUC4 knockout cells possess less tumorigenicity in vitro and in vivo, which was further reduced in PDAC cells that express aberrant overexpression of truncated O-glycans. Also, MUC4KO cells showed a further reduction of epidermal growth factor receptors (ErbB) and their downstream signaling pathways in truncated O-glycan expressing PDAC cells. Tn-MUC4 specific 3B11 antibody inhibited MUC4-induced ErbB receptor and its downstream signaling cascades. MUC4 knockout differentially regulates apoptosis and cell cycle arrest in branched and truncated O-glycan expressing PDAC cells. Additionally, MUC4KO cells were found to be more sensitive to gemcitabine treatment. They possessed the upregulated expression of hENT1 and hCNT3 compared to parental cells, which were further affected in cells with aberrant O-glycosylation. Taken together, our results indicate that MUC4 enhances the malignant properties and gemcitabine resistance in PDAC tumors that aberrantly overexpress truncated O-glycans via altering ErbB/AKT signaling cascades and expression of nucleoside transporters, respectively.

MUC4 is expressed in alveolar rhabdomyosarcoma

AIMS

Mucin 4 (MUC4) is a transmembrane glycoprotein normally expressed by several human epithelial surfaces, including those of the colon, vagina, and respiratory tract. Although MUC4 overexpression is seen in various carcinomas, its expression among mesenchymal neoplasms is fairly specific to low-grade fibromyxoid sarcoma and sclerosing epithelioid fibrosarcoma. Having observed unanticipated anti-MUC4 immunoreactivity in rhabdomyosarcoma, we aimed to further characterise its expression.

METHODS AND RESULTS

Expression of MUC4 was assessed by immunohistochemistry in a total of 97 rhabdomyosarcomas using formalin-fixed paraffin-embedded tissue sections. MUC4 was expressed by 21 of 26 PAX3/7-FOXO1 fusion-positive cases, wherein immunoreactivity, varying from weak to strong, was present in 20-100% of neoplastic cells. With the exception of one sclerosing rhabdomyosarcoma showing immunoreactivity in 20% of cells, MUC4 was not expressed by embryonal (n = 28), sclerosing (n = 20), or pleomorphic (n = 23) rhabdomyosarcomas. Analysing published gene expression microarray data from a separate cohort of 33 fusion-positive and 25 fusion-negative rhabdomyosarcomas, we found on average a 11.4-fold increased expression in fusion-positive tumours (P = 0.0004).

CONCLUSIONS

MUC4 is expressed to a variable extent in the majority of PAX3/7-FOXO1 fusion-positive (alveolar) rhabdomyosarcomas, while expression in other rhabdomyosarcoma subtypes is rare.

Mucin 4 mutation is associated with tumor mutation burden and promotes antitumor immunity in colon cancer patients

At present, immunotherapy is widely used for different mismatch repair (dMMR) or highly microsatellite instability (MSI-H) colorectal cancer patients, and tumor mutation burden (TMB) is a valuable independent predictor of response to immunotherapy. However, specific gene mutations and their relationship with TMB and tumor-infiltrating immune cells in colon cancer remains unclear. In the present study, we analyzed somatic mutation data of colon cancer from The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) datasets, and found that 17 frequently mutated genes were occurred in both cohorts, including APC, TP53, TNN, KRAS, MUC16, MUC4 (mucin 4), SYNE1, FLG, FAT4, OBSCN, FAT3, RYR2, PIK3CA, FBXW7, DNAH11, MUC5B and ZFHX4. Interestingly, only MUC4 mutation was associated with higher TMB and patient clinical prognosis among the 17 mutated genes. Moreover, according to gene set enrichment analysis (GSEA) and the CIBERSORT algorithm, we revealed that MUC4 mutation activated signaling pathways involved in the immune system and enhanced the antitumor immune response. In conclusion, MUC4 may have important clinical implications for immune therapy of colon cancer.

A pan-cancer single-cell transcriptional atlas of tumor infiltrating myeloid cells

Tumor-infiltrating myeloid cells (TIMs) are key regulators in tumor progression, but the similarity and distinction of their fundamental properties across different tumors remain elusive. Here, by performing a pan-cancer analysis of single myeloid cells from 210 patients across 15 human cancer types, we identified distinct features of TIMs across cancer types. Mast cells in nasopharyngeal cancer were found to be associated with better prognosis and exhibited an anti-tumor phenotype with a high ratio of TNF+/VEGFA+ cells. Systematic comparison between cDC1- and cDC2-derived LAMP3+ cDCs revealed their differences in transcription factors and external stimulus. Additionally, pro-angiogenic tumor-associated macrophages (TAMs) were characterized with diverse markers across different cancer types, and the composition of TIMs appeared to be associated with certain features of somatic mutations and gene expressions. Our results provide a systematic view of the highly heterogeneous TIMs and suggest future avenues for rational, targeted immunotherapies.

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.

Cell Adhesion Molecules in Plasticity and Metastasis

Prior to metastasis, modern therapeutics and surgical intervention can provide a favorable long-term survival for patients diagnosed with many types of cancers. However, prognosis is poor for patients with metastasized disease. Melanoma is the deadliest form of skin cancer, yet in situ and localized, thin melanomas can be biopsied with little to no postsurgical follow-up. However, patients with metastatic melanoma require significant clinical involvement and have a 5-year survival of only 34% to 52%, largely dependent on the site of colonization. Melanoma metastasis is a multi-step process requiring dynamic changes in cell surface proteins regulating adhesiveness to the extracellular matrix (ECM), stroma, and other cancer cells in varied tumor microenvironments. Here we will highlight recent literature to underscore how cell adhesion molecules (CAM) contribute to melanoma disease progression and metastasis.

NCAPG confers trastuzumab resistance via activating SRC/STAT3 signaling pathway in HER2-positive breast cancer

HER2+ breast cancer (BC) is characterized by rapid growth, early recurrence, early metastasis, and chemoresistance. Trastuzumab is the most effective treatment for HER2+ BC and effectively reduces the risk of recurrence and death of patients. Resistance to trastuzumab results in cancer recurrence and metastasis, leading to poor prognosis of HER2+ BC. In the present study, we found that non-structural maintenance of chromosome condensin 1 complex subunit G (NCAPG) expression was highly upregulated in trastuzumab-resistant HER2+ BC. Ectopic NCAPG was positively correlated with tumor relapse and shorter survival in HER2+ BC patients. Moreover, overexpression of NCAPG promoted, while silencing of NCAPG reduced, the proliferative and anti-apoptotic capacity of HER2+ BC cells both in vitro and in vivo, indicating NCAPG reduces the sensitivity of HER2+ BC cells to trastuzumab and may confer trastuzumab resistance. Furthermore, our results suggest that NCAPG triggers a series of biological cascades by phosphorylating SRC and enhancing nuclear localization and activation of STAT3. To summarize, our study explores a crucial role for NCAPG in trastuzumab resistance and its underlying mechanisms in HER2+ BC, and suggests that NCAPG could be both a potential prognostic marker as well as a therapeutic target to effectively overcome trastuzumab resistance.

Genomic characterization of Chinese ovarian clear cell carcinoma identifies driver genes by whole exome sequencing

Little is known about the genetic alterations characteristic of ovarian clear cell carcinoma (OCCC). Our aim was to identify targetable genomic alterations in this type of cancer. Forty-two OCCC formalin-fixed, paraffin-embedded (FFPE) tissue samples were analyzed by whole-exome sequencing (WES), and 74 FFPE tissue samples underwent targeted sequencing (TS) to confirm the relevant driver mutations. Cell proliferation was assessed by cell counting kit-8 (CCK8) assays. In the 42 samples, ARID1A (64.3%) and PIK3CA (28.5%) were frequently mutated, as were PPP2R1A (11.9%), PTEN (7.1%) and KRAS (4.8%), which have been reported in previous OCCC studies. We also detected mutations in MUC4 (28.6%), MAGEE1 (19%), and ARID3A (16.7%); associations with these genes have not been previously reported. The functional protein-activated pathways were associated with proliferation and survival (including the PI3K/AKT, TP53, and ERBB2 pathways) in 83% of OCCCs and with chromatin remodeling in 71% of OCCCs. Patients with alterations in MAGEE1 (64% in the targeted sequencing cohort) had worse clinical outcomes (log-rank p < 0.05). A functional study revealed that two MAGEE1 mutants, one lacking two MAGE domains and the other containing two MAGE domains, significantly decreased the proliferative capacity of OCCC cells. We successfully identified novel genetic alterations in OCCC using whole-exome sequencing and targeted sequencing of OCCC patient samples and potential therapeutic targets for the treatment of this malignancy.

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.

Assessing the prognostic significance of MUC4β in mucoepidermoid carcinoma of the salivary glands: An immunohistochemical study

Objectives

– Routine histopathological grading for salivary gland mucoepidermoid carcinoma (MEC) have failed to prognosticate these tumors, resulting in poor post-surgical outcomes. In developing countries, the lack of technologically advanced infrastructure curtails, efficient treatment modalities. This study aimed at determining if MUC4β can characterize salivary gland MEC and serve as a practical and inexpensive method to prognosticate salivary gland MEC.

Materials and methods

– Fifteen cases of archived paraffin embedded tissue blocks of mucoepidermoid carcinomas were reassessed for histopathological grading using Healey's system, modified by Batsakis and Luna and immunohistochemically evaluated for expression of MUC4β. Statistical analysis (Kappa statistics and Spearman's rho correlation coefficient) was performed to assess inter-observer reproducibility and to correlate the expression of MUC4β with the histopathological grade of the tumor.

Results

MUC4β expression is related to tumor differentiation in an inverse relationship. Two cases of high grade MEC were the exception to this rule.

Conclusion

Our study revealed that MUC4β alone cannot serve as a reliable prognostic marker due to its divergent tumor suppressor and oncogenic pathway. The role of MUC4β needs further evaluation and research so as to potentiate therapeutics depending upon its context dependent function, as a cancer marker or an oncogenic factor.

MUC4-ErbB2 Oncogenic Complex: Binding studies using Microscale Thermophoresis

The MUC4 membrane-bound mucin is a large O-glycoprotein involved in epithelial homeostasis. At the cancer cell surface MUC4 interacts with ErbB2 receptor via EGF domains to promote cell proliferation and migration. MUC4 is highly regarded as a therapeutic target in pancreatic cancer as it is not expressed in healthy pancreas, while it is neoexpressed in early preneoplastic stages (PanINs). However, the association/dissociation constant of MUC4-ErbB2 complex is unknown. Protein-protein interactions (PPIs) have become a major area of research in the past years and the characterization of their interactions, especially by biophysical methods, is intensively used in drug discovery. To characterize the MUC4-ErbB2 interaction, we used MicroScale Thermophoresis (MST), a powerful method for quantitative protein interaction analysis under challenging conditions. We worked with CHO cell lysates containing either the transmembrane β subunit of MUC4 (MUC4β) or a truncated mutant encompassing only the EGF domains (MUC4_EGF3+1+2). MST studies have led to the characterization of equilibrium dissociation constants (K_d) for MUC4β-ErbB2 (7–25 nM) and MUC4_EGF3+1+2/ErbB2 (65–79 nM) complexes. This work provides new information regarding the MUC4-ErbB2 interaction at the biophysical level and also confirms that the presence of the three EGF domains of MUC4 is sufficient to provide efficient interaction. This technological approach will be very useful in the future to validate small molecule binding affinities targeting MUC4-ErbB2 complex for drug discovery development in cancer. It will also be of high interest for the other known membrane mucins forming oncogenic complexes with ErbBs at the cancer cell surface.

Mechanisms of Receptor Tyrosine-Protein Kinase ErbB-3 (ERBB3) Action in Human Neoplasia

It is well established that the epidermal growth factor (EGF) receptor, receptor tyrosine-protein kinase erbB-2 (ERBB2)/human EGF receptor 2 (HER2), and, to a lesser extent, ERBB4/HER4, promote the pathogenesis of many types of human cancers. In contrast, the role that ERBB3/HER3, the fourth member of the ERBB family of receptor tyrosine kinases, plays in these diseases is poorly understood and, until recently, underappreciated. In large part, this was because early structural and functional studies suggested that ERBB3 had little, if any, intrinsic tyrosine kinase activity and, thus, was unlikely to be an important therapeutic target. Since then, however, numerous publications have demonstrated an important role for ERBB3 in carcinogenesis, metastasis, and acquired drug resistance. Furthermore, somatic ERBB3 mutations are frequently encountered in many types of human cancers. Dysregulation of ERBB3 trafficking as well as cooperation with other receptor tyrosine kinases further enhance ERBB3's role in tumorigenesis and drug resistance. As a result of these advances in our understanding of the structure and biochemistry of ERBB3, and a growing focus on the development of precision and combinatorial therapeutic regimens, ERBB3 is increasingly considered to be an important therapeutic target in human cancers. In this review, we discuss the unique structural and functional features of ERBB3 and how this information is being used to develop effective new therapeutic agents that target ERBB3 in human cancers.

Low mutational load in pediatric medulloblastoma still translates into neoantigens as targets for specific T-cell immunotherapy

BACKGROUND

Medulloblastoma is the most common malignant brain tumor in childhood and adolescence. Although some patients present with distinct genetic alterations, such as mutated TP53 or MYC amplification, pediatric medulloblastoma is a tumor entity with minimal mutational load and low immunogenicity.

METHODS

We identified tumor-specific mutations using next-generation sequencing of medulloblastoma DNA and RNA derived from primary tumor samples from pediatric patients. Tumor-specific mutations were confirmed using deep sequencing and in silico analyses predicted high binding affinity of the neoantigen-derived peptides to the patients' human leukocyte antigen molecules. Tumor-specific peptides were synthesized and used to induce a de novo T-cell response characterized by interferon gamma and tumor necrosis factor alpha release of CD8⁺ cytotoxic T cells in vitro.

RESULTS

Despite low mutational tumor burden, at least two immunogenic tumor-specific peptides were identified in each patient. T cells showed a balanced CD4/CD8 ratio and mostly effector memory phenotype. Induction of a CD8-specific T-cell response was achieved for the neoepitopes derived from Histidine Ammonia-Lyase (HAL), Neuraminidase 2 (NEU2), Proprotein Convertase Subtilisin (PCSK9), Programmed Cell Death 10 (PDCD10), Supervillin (SVIL) and tRNA Splicing Endonuclease Subunit 54 (TSEN54) variants.

CONCLUSION

Detection of patient-specific, tumor-derived neoantigens confirms that even in tumors with low mutational load a molecular design of targets for specific T-cell immunotherapy is possible. The identified neoantigens may guide future approaches of adoptive T-cell transfer, transgenic T-cell receptor transfer or tumor vaccination.

Chemotherapy is associated with increased survival from colorectal signet ring cell carcinoma with distant metastasis: A Surveillance, Epidemiology, and End Results database analysis

Background

Colorectal signet ring cell carcinoma (SRCC) is a rare histological subtype of colorectal adenocarcinoma with high metastatic frequency compared to non‐SRCC colorectal cancer (NOS). The aim of this study was to analyze prognostic factors of colorectal SRCC with different metastatic sites and evaluate impacts of various therapies for metastatic colorectal SRCC.

Methods

Patients with NOS and SRCC were from the Surveillance, Epidemiology, and End Results (SEER) database during 2010‐2014. χ² tests were used to compare data significance. Kaplan‐Meier and COX models were used to analyze the differences in the survival. Propensity‐matched analyses were used to adjust numerical differences.

Results

Among the 173 460 patients, 1932 (1.11%) patients had colorectal SRCC. In univariate analysis, older age, male sex, and peritoneum metastasis were associated with higher mortality risk. The peritoneum was both the site with the highest metastatic frequency and the site with the worst prognosis in SRCC. In the COX regression model, peritoneum‐metastatic SRCC patients receiving chemotherapy had better survival than patients treated with surgery.

Conclusions

Our study analyzed the unique metastatic pattern of colorectal SRCC toward different sites and found that compared to surgery, chemotherapy was associated with better survival for colorectal SRCC patients with distant metastasis, which provided insights for future SRCC patient treatment.

Untouchable genes in the human genome: Identifying ideal targets for cancer treatment

BACKGROUND

Usually, genes with a higher-than-expected number of somatic mutations in tumor samples are assumed to be cancer related. We identified genes with a fewer-than-expected number of somatic mutations - "untouchable genes".

METHODS

To predict the expected number of somatic mutations, we used a linear regression model with the number of mutations in the gene as an outcome, and gene characteristics, including gene size, nucleotide composition, level of evolutionary conservation, expression level and others, as predictors. Analysis of residuals from the regression model was used to compare the observed and predicted number of mutations.

RESULTS

We have identified 19 genes with a less-than-expected number of loss-off-function (nonsense, frameshift or pathogenic missense) mutations - i.e., untouchable genes. The number of silent or neutral missense mutations in untouchable genes was equal or higher than the expected number. Many mucins, including MUC16, MUC17, MUC6, MUC5AC, MUC5B, and MUC12, are untouchable. We hypothesized that untouchable mucins help tumor cells to avoid immune response by providing a protective coat that prevents direct contact between effector immune cells, e.g., cytotoxic T-cells, and tumor cells. Survival analysis of available TCGA data demonstrated that overall survival of patients with low (below the median) expression of untouchable mucins was better compared to patients with high expression of untouchable mucins. Aside from mucins, we have identified a number of other untouchable genes.

CONCLUSIONS

Untouchable genes may be ideal targets for cancer treatment since suppression of untouchable genes is expected to inhibit survival of tumor cells.

miR-581-Related Single Nucleotide Polymorphism, rs2641726, Located in MUC4 Gene, is Associated with Gastric Cancer Incidence

MUC4 is aberrantly expressed in several carcinomas including breast, colon, ovarian, lung, prostate, stomach and pancreatic cancers. MUC4 can regulate cell apoptosis negatively and facilitate stomach tumorigenesis. In this research, we aimed to evaluate the possible association between rs2641726 (C > A) polymorphism of MUC4 and gastric cancer risk in the Iranian population. In this case-control study, we collected blood samples from 168 gastric cancer patients and 66 healthy subjects. Allele-specific primer polymerase chain reaction method was applied to genotype rs2641726 in the obtained DNA samples. This study demonstrated that rs2641726 C allele was significantly associated with the incidence of gastric cancer, odds ratio = 3.382, 95% confidence interval: 1.840-6.217 (P < 0.001). Furthermore, the distribution of this risk allele was highly enriched in the samples with stage III. In silico studies revealed that the C allele of rs2641726, located within MUC4 3'UTR, is potential to attenuate the interaction between miR-581 and MUC4 mRNA. This disturbing effect, which might result in higher expression of MUC4 oncoprotein, was proposed for the mechanism of action of the rs2641726 risk allele. rs2641726 C allele is significantly enriched in gastric cancer specimens. The attenuating effect of this allele on miR-581 and MUC4 interaction might be a potential mechanism of action by which C allele imposes its oncogenic impact.

QSurface: fast identification of surface expression markers in cancers

Background

Cell surface proteins have provided useful targets and biomarkers for advanced cancer therapies. The recent clinical success of antibody-drug conjugates (ADCs) highlights the importance of finding selective surface antigens for given cancer subtypes. We thus attempted to develop stand-alone software for the analysis of the cell surface transcriptome of patient cancer samples and to prioritize lineage- and/or mutation-specific over-expression markers in cancer cells.

Results

A total of 519 genes were selected as surface proteins, and their expression was profiled in 14 cancer subtypes using patient sample transcriptome data. Lineage/mutation-oriented analysis was used to identify subtype-specific surface markers with statistical confidence. Experimental validation confirmed the unique over-expression of predicted surface markers (MUC4, MSLN, and SLC7A11) in lung cancer cells at the protein level. The differential cell surface gene expression of cell lines may differ from that of tissue samples due to the absence of the tumor microenvironment.

Conclusions

In the present study, advanced 3D models of lung cell lines successfully reproduced the predicted patterns, demonstrating the physiological relevance of cell line-based 3D models in validating surface markers from patient tumor data. Also QSurface software is freely available at http://compbio.sookmyung.ac.kr/~qsurface.

Electronic supplementary material

The online version of this article (10.1186/s12918-018-0541-6) contains supplementary material, which is available to authorized users.

Whole exome sequencing identified sixty-five coding mutations in four neuroblastoma tumors

Neuroblastoma is a pediatric tumor characterized by histologic heterogeneity, and accounts for ~15% of childhood deaths from cancer. The five-year survival for patients with high-risk stage 4 disease has not improved in two decades. We used whole exome sequencing (WES) to identify mutations present in three independent high-risk stage 4 neuroblastoma tumors (COA/UAB-3, COA/UAB -6 and COA/UAB -8) and a stage 3 tumor (COA/UAB-14). Among the four tumors WES analysis identified forty-three mutations that had not been reported previously, one of which was present in two of the four tumors. WES analysis also corroborated twenty-two mutations that were reported previously. No single mutation occurred in all four tumors or in all stage 4 tumors. Three of the four tumors harbored genes with CADD scores ≥20, indicative of mutations associated with human pathologies. The average depth of coverage ranged from 39.68 to 90.27, with >99% sequences mapping to the genome. In summary, WES identified sixty-five coding mutations including forty-three mutations not reported previously in primary neuroblastoma tumors. The three stage 4 tumors contained mutations in genes encoding protein products that regulate immune function or cell adhesion and tumor cell metastasis.

Cell membrane-anchored MUC4 promotes tumorigenicity in epithelial carcinomas

The cell surface membrane-bound mucin protein MUC4 promotes tumorigenicity, aggressive behavior, and poor outcomes in various types of epithelial carcinomas, including pancreatic, breast, colon, ovarian, and prostate cancer. This review summarizes the theories and findings regarding MUC4 function, and its role in epithelial carcinogenesis. Based on these insights, we developed an outline of the processes and mechanisms by which MUC4 critically supports the propagation and survival of cancer cells in various epithelial organs. MUC4 may therefore be a useful prognostic and diagnostic tool that improves our ability to eradicate various forms of cancer.

Vascular-Associated Muc4/Vwf Co-Localization in Human Conjunctival Malignant Melanoma Specimens-Tumor Metastasis by Migration?

PURPOSE

To investigate whether vascular differentiation marker von Willebrand factor (vWf) and proliferation marker KI67 expression correlate with MUC4 localization around stromal tumor vascularization in human conjunctival malignant melanoma (CMM).

MATERIALS AND METHODS

For the purposes of this study, we analyzed samples from human CMMs (n = 4), conjunctival compound nevi (n = 7), and samples from healthy conjunctiva (n = 7) for MUC1, 4, and 16 by immunohistochemistry. To test CMM vessel association of MUC4, we investigated the co-localization of MUC4 with vWf or KI67 in human CMM specimens (n = 10) by immunohistochemistry. Also, we investigated the MUC4 localization around vessels of healthy conjunctiva (n = 10).

RESULTS

The immunohistochemical analysis demonstrated membrane-associated mucin expression in epithelia of CMM, nevi and healthy conjunctiva, whereas only MUC4 was localized perivascular in CMM tissue in this preliminary analysis. Co-staining analysis with vWf and KI67 demonstrated MUC4 localization around stromal vessels in human CMM specimens. In contrast, no MUC4 localization has been seen around healthy conjunctiva stroma vessels.

CONCLUSIONS

MUC4 was detected around vWf/KI67-positive CMM stromal vascular tissue, but not around healthy conjunctival stroma vessels. Therefore, we assume that MUC4 might play a role in tumor cell migration toward vessels inducing metastasis.

N-Acetylcysteine breaks resistance to trastuzumab caused by MUC4 overexpression in human HER2 positive BC-bearing nude mice monitored by 89Zr-Trastuzumab and 18F-FDG PET imaging

Trastuzumab remains an important drug in the management of human epidermal growth factor receptor 2 (HER2) overexpressing breast cancer (BC). Several studies reported resistance mechanisms to trastuzumab, including impaired HER2-accessibility caused by mucin 4 (MUC4). Previously, we demonstrated an increase of Zirconium-89-radiolabeled-trastuzumab (⁸⁹Zr-Trastuzumab) accumulation when MUC4-overexpressing BC-cells were challenged with the mucolytic drug N-Acetylcysteine (NAC). Hereby, using the same approach we investigated whether tumor exposure to NAC would also enhance trastuzumab-efficacy.

Dual SKBr3 (HER2+/MUC4-, sensitive to trastuzumab) and JIMT1 (HER2+/MUC4+, resistant to trastuzumab) HER2-BC-bearing-xenografts were treated with trastuzumab and NAC. Treatment was monitored by molecular imaging evaluating HER2-accessibility/activity (⁸⁹Zr-Trastuzumab HER2-immunoPET) and glucose metabolism (¹⁸F-FDG-PET/CT), as well as tumor volume and the expression of key proteins.

In the MUC4-positive JIMT1-tumors, the NAC-trastuzumab combination resulted in improved tumor-growth control compared to trastuzumab alone; with smaller tumor volume/weight, lower 18F-FDG uptake, lower %Ki67 and pAkt-expression. NAC reduced MUC4-expression, but did not affect HER2-expression or the trastuzumab-sensitivity of the MUC4-negative SKBr3-tumors.

These findings suggest that improving HER2-accessibility by reducing MUC4-masking with the mucolytic drug NAC, results in a higher anti-tumor effect of trastuzumab. This provides a rationale for the potential benefit of this approach to possibly treat a subset of HER2-positive BC overexpressing MUC4.

Mucin 4 and matrix metalloproteinase 7 as novel salivary biomarkers for periodontitis

AIM

Periodontitis is a chronic inflammatory disease, characterized by irreversible destruction of tooth-supporting tissue including alveolar bone. We recently reported mucin 4 (MUC4) and matrix metalloproteinase 7 (MMP7) as highly associated with periodontitis in gingival tissue biopsies. The aim of this study was to further investigate the levels of MUC4 and MMP7 in saliva and gingival crevicular fluid (GCF) samples of patients with periodontitis.

MATERIALS AND METHODS

Saliva and GCF samples were collected from periodontitis patients and healthy controls. The levels of MUC4, MMP7, and total protein concentrations were analysed using ELISA or Bradford assay.

RESULTS

MUC4 levels were significantly lower in saliva and GCF from periodontitis patients relative to healthy controls. MMP7 levels were significantly higher in saliva and GCF from periodontitis patients. Multivariate analysis revealed that MUC4 was significantly associated with periodontitis after adjusting for age and smoking habits and, moreover, that the combination of MUC4 and MMP7 accurately discriminated periodontitis from healthy controls.

CONCLUSIONS

MUC4 and MMP7 may be utilized as possible novel biomarkers for periodontitis.

MUC4 impairs the anti-inflammatory effects of corticosteroids in patients with chronic rhinosinusitis with nasal polyps

BACKGROUND

Current evidence suggests that membrane-tethered mucins could mediate corticosteroid efficacy, interacting with glucocorticoid receptor (GR) in patients with chronic rhinosinusitis with nasal polyps (CRSwNP). Mucin 4 (MUC4)-tethered mucin is expressed in nasal polyp (NP) epithelial cells and upregulated under inflammatory conditions. Moreover, MUC4β has the capacity to interact with other intracellular proteins. We hypothesized that MUC4 modulates corticosteroid efficacy of patients with CRSwNP.

OBJECTIVE

We sought to analyze the role of MUC4 in corticosteroid effectiveness in different cohorts of patients with CRSwNP and elucidate the possible mechanisms involved.

METHODS

Eighty-one patients with CRSwNP took oral corticosteroids for 15 days. Corticosteroid resistance was evaluated by using nasal endoscopy. Expression of MUC4 and MUC4β was evaluated by means of real-time PCR, Western blotting, and immunohistochemistry. BEAS-2B knockdown with RNA interference for MUC4 (small interfering RNA [siRNA]-MUC4) was used to analyze the role of MUC4 in the anti-inflammatory effects of dexamethasone.

RESULTS

Twenty-two patients had NPs resistant to oral corticosteroids. MUC4 expression was upregulated in these patients. In siRNA-MUC4 BEAS-2B airway epithelial cells dexamethasone produced higher anti-inflammatory effects, increased inhibition of phospho-extracellular signal-regulated kinase 1/2, increased mitogen-activated protein kinase phosphatase 1 expression, and increased glucocorticoid response element activation. Immunoprecipitation and immunofluorescence experiments revealed that MUC4β forms a complex with GRα in the nuclei of NP epithelial cells from corticosteroid-resistant patients.

CONCLUSION

MUC4β participates in the corticosteroid resistance process, inhibiting normal GRα nuclear function. The high expression of MUC4 in patients with CRSwNP might participate in corticosteroid resistance.

MUC4-promoted neural invasion is mediated by the axon guidance factor Netrin-1 in PDAC

Neuralinvasion (NI) is an important oncological feature of pancreatic ductal adenocarcinoma (PDAC). However, the underlying mechanism of NI in PDAC remains unclear. In this study, we found that MUC4 was overexpressed in PDAC tissues and high expression of MUC4 indicated a higher NI incidencethan low expression. In vitro, MUC4 knockdown inhibited the migration and invasion of PDAC cells and impaired the migration of PDAC cells along nerve in dorsal root ganglia (DRG)-PDAC cell co-culture assay. In vivo, MUC4 knockdown suppressed the NI of PDAC cells in a murine NI model. Mechanistically, our data revealed that MUC4 silencing resulted in decreased netrin-1 expression and re-expression of netrin-1 in MUC4-silenced cells rescued the capability of NI. Furthermore, we identified that decreased netrin-1 expression was owed to the downregulation of HER2/AKT/NF-κB pathway in MUC4-silenced cells. Additionally, MUC4 knockdown also resulted in the downregulation of pFAK, pSrc, pJNK and MMP9. Taken together, our findings revealed a novelrole of MUC4 in potentiating NI via netrin-1 through the HER2/AKT/NF-κBpathway in PDAC.

The genomic landscape of fibrolamellar hepatocellular carcinoma: whole genome sequencing of ten patients

Fibrolamellar hepatocellular carcinoma is a rare, malignant liver tumor that often arises in the otherwise normal liver of adolescents and young adults. Previous studies have focused on biomarkers and comparisons to traditional hepatocellular carcinoma, and have yielded little data on the underlying pathophysiology. We performed whole genome sequencing on paired tumor and normal samples from 10 patients to identify recurrent mutations and structural variations that could predispose to oncogenesis. There are relatively few coding, somatic mutations in this cancer, putting it on the low end of the mutational spectrum. Aside from a previously described heterozygous deletion on chromosome 19 that encodes for a functional, chimeric protein, there were no other recurrent structural variations that contribute to the tumor genotype. The lack of a second-hit mutation in the genomic landscape of fibrolamellar hepatocellular carcinoma makes the DNAJB1-PRKACA fusion protein the best target for diagnostic and therapeutic advancements. The mutations, altered pathways and structural variants that characterized fibrolamellar hepatocellular carcinoma were distinct from those in hepatocellular carcinoma, further defining it as a distinct carcinoma.

Clinicopathological and prognostic significance of MUC4 expression in cancers: evidence from meta-analysis

Mucin4 (MUC4) is a secreted glycoprotein. Numerous studies had indicated that MUC4 was an attractive prognostic tumor biomarker. However, the results of different studies have been inconsistent. So we conducted this meta-analysis to explore the association between MUC4 expression and cancer prognosis. A systematically comprehensive search was performed through PubMed, EMBASE and CNKI (Chinese National Knowledge Infrastructure). Prognostic value of MUC4 expression in malignancy patients was evaluated by pooled hazard ratios (HRs) and their 95% confidence intervals (CIs). Meanwhile, pooled odds ratio (OR) with 95% CI was appropriate for the association between MUC4 expression and clinicopathological parameters. Eighteen studies including 1,933 patients were enrolled in this meta-analysis. Significant association was found between elevated MUC4 expression and poorer overall survival (OS) with pooled hazard ratio (HR) of 1.87 [95% confidence interval (CI): 1.58-2.23, P<0.001]. Significant associations were also detected in biliary tract carcinoma (HR: 2.41, 95% CI: 1.69-3.42, P<0.001), pancreatic cancer (HR: 2.01, 95% CI: 1.42-2.86, P<0.001) and colorectal cancer (HR: 1.73, 95% CI: 1.17-2.54, P=0.006). Moreover, combined odds ratio (OR) of MUC4 indicated that MUC4 overexpression was associated with tumor stage, tumor invasion and lymph node metastasis. Our results demonstrated that MUC4 may be exploited as a novel prognostic biomarker for cancer patients.

An update on the application of newly described immunohistochemical markers in soft tissue pathology

CONTEXT

During the last 5 to 10 years, significant progress has been made in the molecular characterization of soft tissue tumors, predominantly with the identification of recurrent translocations or amplification of certain genes in different tumor types. Alongside this, translational efforts have identified many novel and diagnostically useful immunohistochemical markers for many of these tumor types.

OBJECTIVE

This article reviews a select group of recently described immunohistochemical markers of particular use in the evaluation of mesenchymal neoplasms; the underlying biology of the protein product, practical utility, and limitations of each marker are discussed in detail.

DATA SOURCES

Literature review, authors' research data, and personal practice experience serve as sources.

CONCLUSIONS

There are many diagnostically useful immunohistochemical markers to help confirm the diagnosis of many different soft tissue tumor types, some of which have reduced the need for additional, and more costly, studies, such as fluorescence in situ hybridization. However, no one marker is 100% specific for a given tumor, and knowledge of potential pitfalls and overlap in patterns of staining among other tumor types is crucial to ensure the appropriate application of these markers in clinical practice.

OCAM regulates embryonic spinal cord stem cell proliferation by modulating ErbB2 receptor

The proliferation and differentiation of neural stem cells are tightly controlled by intrinsic and extrinsic cues. Cell adhesion molecules are increasingly recognized as regulators of these processes. Here we report the expression of the olfactory cell adhesion molecule (OCAM/NCAM2/RNCAM) during mouse spinal cord development and in neural stem cells cultured as neurospheres. OCAM is also weakly expressed in the dormant adult stem cell niche around the central canal and is overexpressed after spinal cord injury. Both transmembrane (TM) and glycosylphosphatidylinositol (GPI)-linked isoforms are present in neurospheres. Electron microscopy and internalisation experiments revealed a dynamic trafficking of OCAM between the membrane and intracellular compartments. After differentiation, OCAM remains in neurons and oligodendrocytes whereas no expression is detected in astrocytes. Using OCAM knockout (KO) mice, we found that mutant spinal cord stem cells showed an increased proliferation and self-renewal rates although no effect on differentiation was observed. This effect was reversed by lentivirus-mediated re-introduction of OCAM. Mechanistically, we identified the ErbB2/Neu/HER2 protein as being implicated in the enhanced proliferation of mutant cells. ErbB2 protein expression and phosphorylation level were significantly increased in KO cells whereas no difference was observed at the mRNA level. Overexpression of ErbB2 in wild-type and mutant cells also increased their growth while reintroduction of OCAM in mutant cells reduced the level of phosphorylated ErbB2. These results indicate that OCAM exerts a posttranscriptional control on the ErbB2 signalling in spinal cord stem cells. This study adds further support for considering cell adhesion molecules as regulators of the ErbB signalling.

Emerging potential of natural products for targeting mucins for therapy against inflammation and cancer

Deregulated mucin expression is a hallmark of several inflammatory and malignant pathologies. Emerging evidence suggests that, apart from biomarkers, these deregulated mucins are functional contributors to the pathogenesis in inflammation and cancer. Both overexpression and downregulation of mucins in various organ systems is associated with pathobiology of inflammation and cancer. Restoration of mucin homeostasis has become an important goal for therapy and management of such disorders has fueled the quest for selective mucomodulators. With improved understanding of mucin regulation and mechanistic insights into their pathobiological roles, there is optimism to find selective non-toxic agents capable of modulating mucin expression and function. Recently, natural compounds derived from dietary sources have drawn attention due to their anti-inflammatory and anti-oxidant properties and low toxicity. Considerable efforts have been directed towards evaluating dietary natural products as chemopreventive and therapeutic agents; identification, characterization and synthesis of their active compounds; and improving their delivery and bioavailability. We describe the current understanding of mucin regulation, rationale for targeting mucins with natural products and discuss some natural products that modulate mucin expression and functions. We further discuss the approaches and parameters that should guide future research to identify and evaluate selective natural mucomodulators for therapy.