A stat-responsive element in the promoter of the episialin/MUC1 gene is involved in its overexpression in carcinoma cells

Paeoniflorigenone inhibits ovarian cancer metastasis through targeting the MUC1/Wnt/β‑catenin pathway

Ovarian cancer (OC) is one of the most common gynecological malignancies. Currently, chemoradiotherapy is the primary clinical treatment approach for OC; however, it has severe side effects and a high rate of recurrence. Thus, there is an urgent need to develop innovative therapeutic options. Paeoniflorigenone (PFG) is a monoterpene compound isolated from the traditional Chinese medicine Paeoniae Radix Rubra. PFG can inhibit the proliferation of tumor cells; however, its anticancer activity against OC has yet to be elucidated. Mucin 1 (MUC1) is highly expressed in various malignant tumors, and is associated with tumor proliferation, metastasis and epithelial‑mesenchymal transition (EMT). In addition, MUC1 affects numerous signaling pathways in tumor cells. In order to develop a possible treatment approach for metastatic OC, the antitumor activity of PFG in OC cells was investigated using Cell Counting Kit‑8 assay, Edu assay, flow cytometry, Transwell assay and western blot analysis. In addition, it was assessed how PFG affects MUC1 expression and function. The experiments revealed that PFG significantly inhibited OC cell proliferation, migration, invasion and EMT. PFG also induced S‑phase cell cycle arrest in OC cells. Furthermore, PFG inhibited MUC1 promoter activity, which led to a decrease in MUC1 protein expression. By contrast, MUC1 promoted OC progression, including cell proliferation, cell cycle progression and cell migration. Stable knockdown of MUC1 in OC cells improved the ability of PFG to block the Wnt/β‑catenin pathway, and to limit tumor cell invasion and migration, whereas MUC1 overexpression partially counteracted the antitumor effects of PFG. In conclusion, the present study demonstrated that PFG may inhibit the MUC1/Wnt/β‑catenin pathway to induce anti‑metastatic, anti‑invasive and anti‑EMT effects on OC. Notably, MUC1 may be a direct target of PFG. Thus, PFG holds promise as a specific antitumor agent for the treatment of OC.

Molecular crosstalk between MUC1 and STAT3 influences the anti-proliferative effect of Napabucasin in epithelial cancers

MUC1 is a transmembrane glycoprotein that is overexpressed and aberrantly glycosylated in epithelial cancers. The cytoplasmic tail of MUC1 (MUC1 CT) aids in tumorigenesis by upregulating the expression of multiple oncogenes. Signal transducer and activator of transcription 3 (STAT3) plays a crucial role in several cellular processes and is aberrantly activated in many cancers. In this study, we focus on recent evidence suggesting that STAT3 and MUC1 regulate each other's expression in cancer cells in an auto-inductive loop and found that their interaction plays a prominent role in mediating epithelial-to-mesenchymal transition (EMT) and drug resistance. The STAT3 inhibitor Napabucasin was in clinical trials but was discontinued due to futility. We found that higher expression of MUC1 increased the sensitivity of cancer cells to Napabucasin. Therefore, high-MUC1 tumors may have a better outcome to Napabucasin therapy. We report how MUC1 regulates STAT3 activity and provide a new perspective on repurposing the STAT3-inhibitor Napabucasin to improve clinical outcome of epithelial cancer treatment.

The Role of Inflammation-Associated Factors in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC), which originates in the head or neck tissues, is characterized by high rates of recurrence and metastasis. Inflammation is important in HNSCC prognosis. Inflammatory cells and their secreted factors contribute to the various stages of HNSCC development through multiple mechanisms. In this review, the mechanisms through which inflammatory factors, signaling pathways, and cells contribute to the initiation and progression of HNSCC have been discussed in detail. Furthermore, the diagnostic and therapeutic potential of targeting inflammation in HNSCC has been discussed to gain new insights into improving patient prognosis.

hsa-miR-424-5p and hsa-miR-513c-3p dysregulation mediated by IFN-γ is associated with salivary gland dysfunction in Sjögren's syndrome patients

Salivary secretory dysfunction in SS-patients is associated with altered proteostasis, upregulation of ATF6α and components of the ERAD complex, such as SEL1L, and downregulation of XBP-1s and GRP78. Hsa-miR-424-5p is downregulated and hsa-miR-513c-3p is overexpressed in salivary glands from SS-patients. These miRNAs emerged as candidates that could regulate ATF6/SEL1L and XBP-1s/GRP78 levels, respectively. This study aimed to evaluate the effect of IFN-γ on hsa-miR-424-5p and hsa-miR-513c-3p expression and how these miRNAs regulate their targets. In labial salivary glands (LSG) biopsies from 9 SS-patients and 7 control subjects and IFN-γ-stimulated 3D-acini were analyzed. hsa-miR-424-5p and hsa-miR-513c-3p levels were measured by TaqMan assays and their localization by ISH. mRNA, protein levels, and localization of ATF6, SEL1L, HERP, XBP-1s and GRP78 were determined by qPCR, Western blot, or immunofluorescence. Functional and interaction assays were also performed. In LSGs from SS-patients and IFN-γ-stimulated 3D-acini, hsa-miR-424-5p was downregulated and ATF6α and SEL1L were upregulated. ATF6α and SEL1L were decreased after hsa-miR-424-5p overexpression, while ATF6α, SEL1L and HERP increased after hsa-miR-424-5p silencing. Interaction assays revealed that hsa-miR-424-5p targets ATF6α directly. hsa-miR-513c-3p was upregulated and XBP-1s and GRP78 were downregulated. XBP-1s and GRP78 were decreased after hsa-miR-513c-3p overexpression, while increases in XBP-1s and GRP78 were observed after hsa-miR-513c-3p silencing. Furthermore, we determined that hsa-miR-513c-3p targets XBP-1s directly. Significant correlations were found between both miRNA levels and clinical parameters. In conclusion, IFN-γ-dependent hsa-miR-424-5p and hsa-miR-513c-3p levels affect the expression of important factors involved in cellular proteostasis that control secretory function in LSG from SS-patients.

Expression of MUC-2, MUC-6, NAPE-PLD, IL-6 and IL-13 in Healthy and Metaplastic Bronchial Epithelium

Background: The normal tissue structure of the respiratory system is necessary to provide adequate protection of the airways and lungs. Prolonged exposure to trigger factors can result in adaptive mechanism activation and lead to the development of chronic pulmonary diseases or even dysplastic changes. Materials and methods: Respiratory system material with a pseudostratified ciliated epithelium was obtained from 12 patients (aged 16 to 95), and material with a stratified squamosa epithelium was obtained from six patients (aged 23 to 93). Routine staining was performed, and an immunohistochemistry was conducted for MUC-2, MUC-6, NAPE-PLD, IL-6 and IL-13. Results: Inflammatory processes were not detected in any of the specimens. A number of correlations were identified, with the most important being a strong positive correlation for IL-13 between the alveolar epithelium and alveolar macrophages and a strong positive correlation for IL-6 between the alveolar epithelium and alveolar macrophages in the stratified squamous epithelium group. We also detected a statistically significant difference in IL-6 in alveolar macrophages. Conclusions: There were no signs of dysplastic changes in either group. Increased secretion of IL-13 in the stratified squamous epithelium group shows its involvement in metaplastic changes in the bronchial epithelium. The secretion of atypical factors by hyaline cartilage demonstrates its plasticity and adaptability.

The multifaceted role of STAT3 pathway and its implication as a potential therapeutic target in oral cancer

Oral cancer is one of the leading causes of cancer-related deaths, and it has become a matter of serious concern due to the alarming rise in its incidence rate worldwide. Despite recent advancements in oral cancer treatment strategies, there are no significant improvements in patient's survival rate. Among the numerous cell signaling pathways involved in oral cancer development and progression, STAT3 is known to play a multifaceted oncogenic role in shaping the tumor pathophysiology. STAT3 hyperactivation in oral cancer contributes to survival, proliferation, invasion, epithelial to mesenchymal transition, metastasis, immunosuppression, chemoresistance, and poor prognosis. A plethora of pre-clinical and clinical studies have documented the role of STAT3 in the initiation and development of oral cancer and showed that STAT3 inhibition holds significant potential in the prevention and treatment of this cancer. However, to date, targeting STAT3 activation mainly involves inhibiting the upstream signaling molecules such as JAK and IL-6 receptors. The major challenge in targeting STAT3 lies in the complexity of its phosphorylation- and dimerization-independent functions, which are not affected by disrupting the upstream regulators. The present review delineates the significance of the STAT3 pathway in regulating various hallmarks of oral cancer. In addition, it highlights the STAT3 inhibitors identified to date through various preclinical and clinical studies that can be employed for the therapeutic intervention in oral cancer treatment.

Mucin1 and Mucin16: Therapeutic Targets for Cancer Therapy

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

Trace Amine-Associated Receptor 1 (TAAR1) Is a Positive Prognosticator for Epithelial Ovarian Cancer

Trace amine-associated receptor 1 (TAAR1) is a G_αs- protein coupled receptor that plays an important role in the regulation of the immune system and neurotransmission in the CNS. In ovarian cancer cell lines, stimulation of TAAR1 via 3-iodothyronamine (T₁AM) reduces cell viability and induces cell death and DNA damage. Aim of this study was to evaluate the prognostic value of TAAR1 on overall survival of ovarian carcinoma patients and the correlation of TAAR1 expression with clinical parameters. Ovarian cancer tissue of n = 156 patients who were diagnosed with epithelial ovarian cancer (serous, n = 110 (high-grade, n = 80; low-grade, n = 24; unknown, n = 6); clear cell, n = 12; endometrioid, n = 21; mucinous, n = 13), and who underwent surgery at the Department of Obstetrics and Gynecology, University Hospital of the Ludwig-Maximilians University Munich, Germany between 1990 and 2002, were analyzed. The tissue was stained immunohistochemically with anti-TAAR1 and evaluated with the semiquantitative immunoreactive score (IRS). TAAR1 expression was correlated with grading, FIGO and TNM-classification, and analyzed via the Spearman’s rank correlation coefficient. Further statistical analysis was obtained using nonparametric Kruskal-Wallis rank-sum test and Mann-Whitney-U-test. This study shows that high TAAR1 expression is a positive prognosticator for overall survival in ovarian cancer patients and is significantly enhanced in low-grade serous carcinomas compared to high-grade serous carcinomas. The influence of TAAR1 as a positive prognosticator on overall survival indicates a potential prognostic relevance of signal transduction of thyroid hormone derivatives in epithelial ovarian cancer. Further studies are required to evaluate TAAR1 and its role in the development of ovarian cancer.

Differential Effect of Proinflammatory Cytokines on Corneal and Conjunctival Epithelial Cell Mucins and Glycocalyx

Purpose

Ocular surface mucins and glycocalyx are critical for providing ocular hydration as well lubrication and repelling pathogens or allergens. Elevated levels of tear proinflammatory cytokines in dry eye may have detrimental effect on mucins and glycocalyx. The present study tested the effect of proinflammatory cytokines IL-6, TNF-α, and IFN-γ on membrane-tethered mucins expression, glycocalyx, and viability of ocular surface epithelial cells.

Methods

Stratified cultures of human corneal and conjunctival epithelial cells were exposed to different concentrations of IL-6, TNF-α, and IFN-γ for 24 hours. The mucins gene and protein expressions were quantified by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). The glycocalyx was imaged using confocal microscopy after staining with Alexa 488-conjugated wheat germ agglutinin lectin. Apoptotic and necrotic cell death was quantified using flow cytometry.

Results

IL-6, TNF-α, and IFN-γ treatment resulted in a significant increase in mucins (MUC)1 and MUC4 gene and protein expression in human corneal epithelial cells but caused no significant changes in the levels of these mucins in conjunctival epithelial cells. Further, these cytokines decreased MUC16 expression in both corneal and conjunctival epithelial cells. Moreover, no notable change in glycocalyx or apoptotic cell death in corneal and conjunctival epithelial cells was noted with any of the tested cytokines, but IL-6 and TNF-α exposure increased necrotic cell death in corneal and conjunctival epithelial cells, respectively.

Conclusions

Our results demonstrate that proinflammatory cytokines have differential effects on human corneal and conjunctival epithelial cell mucins expression, but do not cause any damage to ocular surface epithelial cell glycocalyx.

Highly glycosylated MUC1 mediates high affinity L-selectin binding at the human endometrial surface

Background

Sialyl-Lewis X/L-selectin high affinity binding interactions between transmembrane O-glycosylated mucins proteins and the embryo have been implicated in implantation processes within the human reproductive system. However, the adhesive properties of these mucins at the endometrial cell surface are difficult to resolve due to known discrepancies between in vivo models and the human reproductive system and a lack of sensitivity in current in vitro models. To overcome these limitations, an in vitro model of the human endometrial epithelial was interrogated with single molecule force spectroscopy (SMFS) to delineate the molecular configurations of mucin proteins that mediate the high affinity L-selectin binding required for human embryo implantation.

Results

This study reveals that MUC1 contributes to both the intrinsic and extrinsic adhesive properties of the HEC-1 cellular surface. High expression of MUC1 on the cell surface led to a significantly increased intrinsic adhesion force (148 pN vs. 271 pN, p < 0.001), whereas this adhesion force was significantly reduced (271 pN vs. 118 pN, p < 0.001) following siRNA mediated MUC1 ablation. Whilst high expression of MUC1 displaying elevated glycosylation led to strong extrinsic (> 400 pN) L-selectin binding at the cell surface, low expression of MUC1 with reduced glycosylation resulted in significantly less (≤200 pN) binding events.

Conclusions

An optimal level of MUC1 together with highly glycosylated decoration of the protein is critical for high affinity L-selectin binding. This study demonstrates that MUC1 contributes to cellular adhesive properties which may function to facilitate trophoblast binding to the endometrial cell surface through the L-selectin/sialyl-Lewis x adhesion system subsequent to implantation.

Prevention of colitis-associated colon cancer using a vaccine to target abnormal expression of the MUC1 tumor antigen

Association between chronic inflammation and cancer development is exemplified by inflammatory bowel disease (IBD) where patients with chronic uncontrolled colitis have a significantly increased risk of developing colitis-associated colorectal cancer (CACC). CACC appears to progresses through the inflammation-dysplasia-carcinoma sequence. This highlights the need to identify targets and interventions that reduce inflammation and prevent development of dysplasia in the context of IBD. Using the dextran sulfate sodium (DSS) mouse model of chronic colitis and CACC, we show that an important target of intervention in human disease would be the epithelial cell molecule MUC1 that is aberrantly expressed on inflamed colonocytes and promotes inflammation and progression to CACC. We show that a MUC1 vaccine can ameliorate chronic colitis and prevent development of dysplasia in the colon and thus extend survival in human MUC1 transgenic mice. This study supports the potential of prophylactic vaccines to target antigens that become aberrantly expressed in chronic inflammation (e.g., IBD) and continue to be expressed on the associated cancers (e.g., colon cancer), to prevent and/or treat both diseases.

Cross-talk between Janus kinase-signal transducer and activator of transcription pathway and transforming growth factor beta pathways and increased collagen1A1 production in uterine leiomyoma cells

OBJECTIVE

To characterize the potential interaction between interleukin-6 (IL6), Janus kinase (JAK)-signal transducer and activator of transcription (STAT)-3 (JAK/STAT3) pathway, and Transforming growth factor beta (TGFβ)-3 , and to determine whether such cross-talk was a contributing factor in the dysregulation of type I collagen production in leiomyomas.

DESIGN

Laboratory study.

SETTING

University research laboratory.

PATIENTS

None.

INTERVENTIONS

Exposure of leiomyoma and myometrial cell lines to IL6 and STAT3 activators/inhibitors. Western immunoblot analysis and immunohistochemistry.

MAIN OUTCOME MEASURES

Expression of STAT3, pSTAT3, SOCS3, COL1A1, and TGFb3.

RESULTS

We observed that IL6 increased pSTAT3 as well as collagen1A1 in uterine leiomyoma cells. Direct activation of the JAK/STAT3 pathway increased collagen1A1 production in leiomyoma cells, whereas inhibition of the pathway significantly decreased collagen1A1 production. We further observed that modulation of the JAK/STAT3 pathway also increased the expression of TGFβ3 protein. Leiomyoma cells exposed to TGFβ3 demonstrated a significant decrease in pSTAT3 protein. Myometrial cells demonstrated a less sensitive response to STAT3 modulation and collagen production.

CONCLUSION

Cross-talk between the TGFβ pathway and JAK/STAT3 pathway contributes to the fibrotic nature of uterine leiomyomas.

Targeting STAT3 signaling using stabilised sulforaphane (SFX-01) inhibits endocrine resistant stem-like cells in ER-positive breast cancer

Estrogen receptor (ER) positive breast cancer is frequently sensitive to endocrine therapy. Multiple mechanisms of endocrine therapy resistance have been identified, including cancer stem-like cell (CSC) activity. Here we investigate SFX-01, a stabilised formulation of sulforaphane (SFN), for its effects on breast CSC activity in ER+ preclinical models. SFX-01 reduced mammosphere formation efficiency (MFE) of ER+ primary and metastatic patient samples. Both tamoxifen and fulvestrant increased MFE and aldehyde dehydrogenase (ALDH) activity of patient-derived xenograft (PDX) tumors, which was reversed by combination with SFX-01. SFX-01 significantly reduced tumor-initiating cell frequency in secondary transplants and reduced the formation of spontaneous lung micrometastases by PDX tumors in mice. Mechanistically, we establish that both tamoxifen and fulvestrant induce STAT3 phosphorylation. SFX-01 suppressed phospho-STAT3 and SFN directly bound STAT3 in patient and PDX samples. Analysis of ALDH+ cells from endocrine-resistant patient samples revealed activation of STAT3 target genes MUC1 and OSMR, which were inhibited by SFX-01 in patient samples. Increased expression of these genes after 3 months' endocrine treatment of ER+ patients (n = 68) predicted poor prognosis. Our data establish the importance of STAT3 signaling in CSC-mediated resistance to endocrine therapy and the potential of SFX-01 for improving clinical outcomes in ER+ breast cancer.

Targeting STAT-3 signaling pathway in cancer for development of novel drugs: Advancements and challenges

Signal transducers and activators of transcription 3 (STAT-3) is a transcription factor that regulates the gene expression of several target genes. These factors are activated by the binding of cytokines and growth factors with STAT-3 specific receptors on cell membrane. Few years ago, STAT-3 was considered an acute phase response element having several cellular functions such as inflammation, cell survival, invasion, metastasis and proliferation, genetic alteration, and angiogenesis. STAT-3 is activated by several types of inflammatory cytokines, carcinogens, viruses, growth factors, and oncogenes. Thus, the STAT3 pathway is a potential target for cancer therapeutics. Abnormal STAT-3 activity in tumor development and cellular transformation can be targeted by several genomic and pharmacological methodologies. An extensive review of the literature has been conducted to emphasize the role of STAT-3 as a unique cancer drug target. This review article discusses in detail the wide range of STAT-3 inhibitors that show antitumor effects both in vitro and in vivo. Thus, targeting constitutive STAT-3 signaling is a remarkable therapeutic methodology for tumor progression. Finally, current limitations, trials and future perspectives of STAT-3 inhibitors are also critically discussed.

Pasteurella multocida specific bacteriophage suppresses P. multocida-induced inflammation: identification of genes related to bacteriophage signaling by Pasteurella multocida-infected swine nasal turbinate cells

BACKGROUND

Although Pasteurella multocida is highly prevalent pathogen in animals and plays an important role in swine respiratory diseases, only a few studies on the use of bacteriophages specific to Pasteurella multocida disease have been reported.

OBJECTIVE

The object of this study was to investigate the therapeutic effect of specific P. multocida bacteriophages and to identify genes related to bacteriophage signaling utilizing RNA microarrays in swine nasal turbinate cells.

METHODS

Pas-MUP-1 phages were applied 24 h prior to P. multocida infection (1 × 10⁷ cfu/ml) at several concentrations of bacterial infection. Cells were incubated to detect cytokines and 24 h to detect mucin production. And real-time quantitative PCR was performed to examine related genes expression. To determine the change of total gene expression based on P. multocida and Pas-MUP-1 treatment, we performed RNA sequencing experiments.

RESULTS

We found that P. multocida-infected PT-K75 cells show increased gene expression of IL-1β, IL-6, and Muc1 in a dose-dependent manner. Interestingly, these genes resulted in decreased expression in P. multocida pretreated with the P. multocida-specific Pas-MUP-1 bacteriophage. RNA sequencing analysis revealed that bacteriophage administration regulated genes associated with immune and inflammatory responses, and the regulated genes were dramatically concentrated in the cytokine/chemokine-based signaling pathways. Pas-MUP-1 treatment was shown to regulate P. multocida induced gene expression in the bacteria.

CONCLUSION

These results suggest the specific bacteriophage has therapeutic potential as an alternative to antibiotic treatment to defend against P. multocida infection by altering inflammatory gene expression profiles.

Mucins as a New Frontier in Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is the most common idiopathic interstitial pulmonary disease with a median survival of 3–5 years after diagnosis. Recent evidence identifies mucins as key effectors in cell growth and tissue remodeling processes compatible with the processes observed in IPF. Mucins are classified in two groups depending on whether they are secreted (secreted mucins) or tethered to cell membranes (transmembrane mucins). Secreted mucins (MUC2, MUC5AC, MUC5B, MUC6-8 and MUC19) are released to the extracellular medium and recent evidence has shown that a promoter polymorphism in the secreted mucin MUC5B is associated with IPF risk. Otherwise, transmembrane mucins (MUC1, MUC3, MUC4, MUC12-17 and MUC20) have a receptor-like structure, sensing the external environment and activating intracellular signal transduction pathways essential for mucosal maintenance and damage repair. In this context, the extracellular domain can be released to the external environment by metalloproteinase action, increased in IPF, thus activating fibrotic processes. For example, several studies have reported increased serum extracellular secreted KL6/MUC1 during IPF acute exacerbation. Moreover, MUC1 and MUC4 overexpression in the main IPF cells has been observed. In this review we summarize the current knowledge of mucins as promising druggable targets for IPF.

CDK5-dependent phosphorylation and nuclear translocation of TRIM59 promotes macroH2A1 ubiquitination and tumorigenicity

Despite the development of adjuvant therapies, glioblastoma (GBM) patients remain incurable, thus justifying the urgent need of new therapies. CDK5 plays a critical role in GBM and is a potential target for GBM. However, the mechanism by which CDK5 promotes GBM tumorigenicity remains largely unknown. Here, we identify TRIM59 as a substrate of CDK5. EGFR-activated CDK5 directly binds to and phosphorylates TRIM59, a ubiquitin ligase at serine 308, which recruits PIN1 for cis–trans isomerization of TRIM59, leading to TRIM59 binding to importin α5 and nuclear translocation. Nuclear TRIM59 induces ubiquitination and degradation of the tumor suppressive histone variant macroH2A1, leading to enhanced STAT3 signaling activation and tumorigenicity. These findings are confirmed by inhibition of CDK5-activated TRIM59 activity that results in suppression of intracranial tumor growth. Correlative expressions of the components of this pathway are clinically prognostic. Our findings suggest targeting CDK5/TRIM59 signaling axis as a putative strategy for treating GBM.

CDK5 is known to drive glioblastoma tumorigenicity but the downstream molecular mechanism is unknown. Here, the authors show that CDK5 activates STAT3 signalling via the nuclear import of TRIM59, which leads to the degradation of the tumour suppressor macroH2A1.

Aberrant MUC1 accumulation in salivary glands of Sjögren’s syndrome patients is reversed by TUDCA in vitro

Objectives

Xerostomia in SS patients has been associated with low quality and quantity of salivary mucins, which are fundamental for the hydration and protection of the oral mucosa. The aim of this study was to evaluate if cytokines induce aberrant mucin expression and whether tauroursodeoxycholic acid (TUDCA) is able to counteract such an anomaly.

Methods

Labial salivary glands from 16 SS patients and 15 control subjects, as well as 3D acini or human submandibular gland cells stimulated with TNF-α or IFN-γ and co-incubated with TUDCA, were analysed. mRNA and protein levels of Mucin 1 (MUC1) and MUC7 were determined by RT-qPCR and western blot, respectively. Co-immunoprecipitation and immunofluorescence assays for mucins and GRP78 [an endoplasmic reticulum (ER)-resident protein] were also performed. mRNA levels of RelA/p65 (nuclear factor-κB subunit), TNF-α, IL-1β, IL-6, SEL1L and EDEM1 were determined by RT-qPCR, and RelA/p65 localization was evaluated by immunofluorescence.

Results

MUC1 is overexpressed and accumulated in the ER of labial salivary gland from SS patients, while MUC7 accumulates throughout the cytoplasm of acinar cells; however, MUC1, but not MUC7, co-precipitated with GRP78. TUDCA diminished the overexpression and aberrant accumulation of MUC1 induced by TNF-α and IFN-γ, as well as the nuclear translocation of RelA/p65, together with the expression of inflammatory and ER stress markers in 3D acini.

Conclusion

Chronic inflammation alters the secretory process of MUC1, inducing ER stress and affecting the quality of saliva in SS patients. TUDCA showed anti-inflammatory properties decreasing aberrant MUC1 accumulation. Further studies are necessary to evaluate the potential therapeutic effect of TUDCA in restoring glandular homeostasis in SS patients.

The Role of the Cell Surface Mucin MUC1 as a Barrier to Infection and Regulator of Inflammation

The family of cell surface (cs-) mucins are constitutively expressed at the cell surface by nearly all epithelial cells, beneath the gel-mucin layer. All cs-mucin family members have structural features that enable them to act as a releasable decoy barrier to mucosal pathogens, by providing ligands for pathogen binding and the ability to shed the bound extracellular domain. Due to the towering structure of cs-mucins at the surface, binding of mucosal pathogens can also sterically block binding to underlying cellular receptors. The cytoplasmic tail domain of cs-mucins are capable of initiating signal transduction cascades and due to their conservation across species, may play an important biological role in cellular signaling. MUC1 is one of the most extensively studied of the cs-mucin family. With respect to its physiological function in the mucosal environment, MUC1 has been demonstrated to play a dynamic role in protection of the host from infection by a wide variety of pathogens and to regulate inflammatory responses to infection. This review briefly summarizes the current knowledge and new findings regarding the structural features relating to the function of MUC1, its role as a protective barrier against pathogen invasion and mechanisms by which this cs-mucin regulates inflammation.

Quantitative proteomics analysis identifies MUC1 as an effect sensor of EGFR inhibition

Tumor responses to cancer therapeutics are generally monitored every 2-3 months based on changes in tumor size. Dynamic biomarkers that reflect effective engagement of targeted therapeutics to the targeted pathway, so-called "effect sensors", would fulfill a need for non-invasive, drug-specific indicators of early treatment effect. Using a proteomics approach to identify effect sensors, we demonstrated MUC1 upregulation in response to epidermal growth factor receptor (EGFR)-targeting treatments in breast and lung cancer models. To achieve this, using semi-quantitative mass spectrometry, we found MUC1 to be significantly and durably upregulated in response to erlotinib, an EGFR-targeting treatment. MUC1 upregulation was regulated transcriptionally, involving PI3K-signaling and STAT3. We validated these results in erlotinib-sensitive human breast and non-small lung cancer cell lines. Importantly, erlotinib treatment of mice bearing SUM149 xenografts resulted in increased MUC1 shedding into plasma. Analysis of MUC1 using serial blood sampling may therefore be a new, relatively non-invasive tool to monitor early and drug-specific effects of EGFR-targeting therapeutics.

CAR T cell therapy for breast cancer: harnessing the tumor milieu to drive T cell activation

BACKGROUND

The adoptive transfer of T cells redirected to tumor via chimeric antigen receptors (CARs) has produced clinical benefits for the treatment of hematologic diseases. To extend this approach to breast cancer, we generated CAR T cells directed against mucin1 (MUC1), an aberrantly glycosylated neoantigen that is overexpressed by malignant cells and whose expression has been correlated with poor prognosis. Furthermore, to protect our tumor-targeted cells from the elevated levels of immune-inhibitory cytokines present in the tumor milieu, we co-expressed an inverted cytokine receptor linking the IL4 receptor exodomain with the IL7 receptor endodomain (4/7ICR) in order to transform the suppressive IL4 signal into one that would enhance the anti-tumor effects of our CAR T cells at the tumor site.

METHODS

First (1G - CD3ζ) and second generation (2G - 41BB.CD3ζ) MUC1-specific CARs were constructed using the HMFG2 scFv. Following retroviral transduction transgenic expression of the CAR±ICR was assessed by flow cytometry. In vitro CAR/ICR T cell function was measured by assessing cell proliferation and short- and long-term cytotoxic activity using MUC1+ MDA MB 468 cells as targets. In vivo anti-tumor activity was assessed using IL4-producing MDA MB 468 tumor-bearing mice using calipers to assess tumor volume and bioluminescence imaging to track T cells.

RESULTS

In the IL4-rich tumor milieu, 1G CAR.MUC1 T cells failed to expand or kill MUC1+ tumors and while co-expression of the 4/7ICR promoted T cell expansion, in the absence of co-stimulatory signals the outgrowing cells exhibited an exhausted phenotype characterized by PD-1 and TIM3 upregulation and failed to control tumor growth. However, by co-expressing 2G CAR.MUC1 (signal 1 - activation + signal 2 - co-stimulation) and 4/7ICR (signal 3 - cytokine), transgenic T cells selectively expanded at the tumor site and produced potent and durable tumor control in vitro and in vivo.

CONCLUSIONS

Our findings demonstrate the feasibility of targeting breast cancer using transgenic T cells equipped to thrive in the suppressive tumor milieu and highlight the importance of providing transgenic T cells with signals that recapitulate physiologic TCR signaling - [activation (signal 1), co-stimulation (signal 2) and cytokine support (signal 3)] - to promote in vivo persistence and memory formation.

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

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

The cell surface mucin MUC1 limits the severity of influenza A virus infection

Cell surface mucin (cs-mucin) glycoproteins are constitutively expressed at the surface of respiratory epithelia where pathogens such as influenza A virus (IAV) gain entry into cells. Different members of the cs-mucin family each express a large and heavily glycosylated extracellular domain that towers above other receptors on the epithelial cell surface, a transmembrane domain that enables shedding of the extracellular domain, and a cytoplasmic tail capable of triggering signaling cascades. We hypothesized that IAV can interact with the terminal sialic acids presented on the extracellular domain of cs-mucins, resulting in modulation of infection efficiency. Utilizing human lung epithelial cells, we found that IAV associates with the cs-mucin MUC1 but not MUC13 or MUC16. Overexpression of MUC1 by epithelial cells or the addition of sialylated synthetic MUC1 constructs, reduced IAV infection in vitro. In addition, Muc1^-/- mice infected with IAV exhibited enhanced morbidity and mortality, as well as greater inflammatory mediator responses compared to wild type mice. This study implicates the cs-mucin MUC1 as a critical and dynamic component of the innate host response that limits the severity of influenza and provides the foundation for exploration of MUC1 in resolving inflammatory disease.

Development of novel antigen receptors for CAR T-cell therapy directed toward solid malignancies

Development of chimeric antigen receptor (CAR) T cells have led to remarkable successes in the treatment of B-cell malignancies with anti-CD19 CAR. Here we discuss the development of novel antigen receptors for use in solid malignancies with respect to target antigens, receptor design, and T cell manipulations.

Interaction of galectin-3 with MUC1 on cell surface promotes EGFR dimerization and activation in human epithelial cancer cells

Epidermal growth factor receptor (EGFR) is an important regulator of epithelial cell growth and survival in normal and cancerous tissues and is a principal therapeutic target for cancer treatment. EGFR is associated in epithelial cells with the heavily glycosylated transmembrane mucin protein MUC1, a natural ligand of galectin-3 that is overexpressed in cancer. This study reveals that the expression of cell surface MUC1 is a critical enhancer of EGF-induced EGFR activation in human breast and colon cancer cells. Both the MUC1 extracellular and intracellular domains are involved in EGFR activation but the predominant influence comes from its extracellular domain. Binding of galectin-3 to the MUC1 extracellular domain induces MUC1 cell surface polarization and increases MUC1–EGFR association. This leads to a rapid increase of EGFR homo-/hetero-dimerization and subsequently increased, and also prolonged, EGFR activation and signalling. This effect requires both the galectin-3 C-terminal carbohydrate recognition domain and its N-terminal ligand multi-merization domain. Thus, interaction of galectin-3 with MUC1 on cell surface promotes EGFR dimerization and activation in epithelial cancer cells. As MUC1 and galectin-3 are both commonly overexpressed in most types of epithelial cancers, their interaction and impact on EGFR activation likely makes important contribution to EGFR-associated tumorigenesis and cancer progression and may also influence the effectiveness of EGFR-targeted cancer therapy.

Role of integrin-linked kinase in regulating the protein stability of the MUC1-C oncoprotein in pancreatic cancer cells

MUC1-C overexpression has been associated with the progression of pancreatic tumors by promoting the aggressive and metastatic phenotypes. As MUC1 is a STAT3 target gene, STAT3 plays a major role in regulating MUC1-C expression. In this study, we report an alternative mechanism by which integrin-linked kinase (ILK) post-transcriptionally modulates the expression of MUC1-C by maintaining its protein stability in pancreatic cancer cells. We found that ILK acts in concert with STAT3 to facilitate IL-6-mediated upregulation of MUC1-C; ILK depletion was equally effective as STAT3 depletion in abolishing IL-6-induced MUC1-C overexpression without disturbing the phosphorylation or cellular distribution of STAT3. Conversely, ectopic expression of constitutively active ILK increased MUC1-C expression, though this increase was not noted with kinase-dead ILK. This finding suggests the requirement of the kinase activity of ILK in regulating MUC1-C stability, which was confirmed by using the ILK kinase inhibitor T315. Furthermore, our data suggest the involvement of protein kinase C (PKC)δ in mediating the suppressive effect of ILK inhibition on MUC1-C repression. For example, co-immunoprecipitation analysis indicated that ILK depletion-mediated MUC1-C phosphorylation was accompanied by increased phosphorylation of PKCδ at the activation loop Thr-507 and increased binding of PKCδ to MUC1-C. Conversely, ILK overexpression resulted in decreased PKCδ phosphorylation. From a mechanistic perspective, the present finding, together with our recent report that ILK controls the expression of oncogenic KRAS through a regulatory loop, underscores the pivotal role of ILK in promoting pancreatic cancer progression.

Transmembrane Mucins: Signaling Receptors at the Intersection of Inflammation and Cancer

Mucosal surfaces line our body cavities and provide the interaction surface between commensal and pathogenic microbiota and the host. The barrier function of the mucosal layer is largely maintained by gel-forming mucin proteins that are secreted by goblet cells. In addition, mucosal epithelial cells express cell-bound mucins that have both barrier and signaling functions. The family of transmembrane mucins consists of diverse members that share a few characteristics. The highly glycosylated extracellular mucin domains inhibit invasion by pathogenic bacteria and can form a tight mesh structure that protects cells in harmful conditions. The intracellular tails of transmembrane mucins can be phosphorylated and connect to signaling pathways that regulate inflammation, cell-cell interactions, differentiation, and apoptosis. Transmembrane mucins play important roles in preventing infection at mucosal surfaces, but are also renowned for their contributions to the development, progression, and metastasis of adenocarcinomas. In general, transmembrane mucins seem to have evolved to monitor and repair damaged epithelia, but these functions can be highjacked by cancer cells to yield a survival advantage. This review presents an overview of the current knowledge of the functions of transmembrane mucins in inflammatory processes and carcinogenesis in order to better understand the diverse functions of these multifunctional proteins.

Aberrant control of NF-κB in cancer permits transcriptional and phenotypic plasticity, to curtail dependence on host tissue: molecular mode

The role of the transcription factor NF-κB in shaping the cancer microenvironment is becoming increasingly clear. Inflammation alters the activity of enzymes that modulate NF-κB function, and causes extensive changes in genomic chromatin that ultimately drastically alter cell-specific gene expression. NF-κB regulates the expression of cytokines and adhesion factors that control interactions among adjacent cells. As such, NF-κB fine tunes tissue cellular composition, as well as tissues' interactions with the immune system. Therefore, NF-κB changes the cell response to hormones and to contact with neighboring cells. Activating NF-κB confers transcriptional and phenotypic plasticity to a cell and thereby enables profound local changes in tissue function and composition. Research suggests that the regulation of NF-κB target genes is specifically altered in cancer. Such alterations occur not only due to mutations of NF-κB regulatory proteins, but also because of changes in the activity of specific proteostatic modules and metabolic pathways. This article describes the molecular mode of NF-κB regulation with a few characteristic examples of target genes.

MUC1-ARF-A Novel MUC1 Protein That Resides in the Nucleus and Is Expressed by Alternate Reading Frame Translation of MUC1 mRNA

Translation of mRNA in alternate reading frames (ARF) is a naturally occurring process heretofore underappreciated as a generator of protein diversity. The MUC1 gene encodes MUC1-TM, a signal-transducing trans-membrane protein highly expressed in human malignancies. Here we show that an AUG codon downstream to the MUC1-TM initiation codon initiates an alternate reading frame thereby generating a novel protein, MUC1-ARF. MUC1-ARF, like its MUC1-TM 'parent’ protein, contains a tandem repeat (VNTR) domain. However, the amino acid sequence of the MUC1-ARF tandem repeat as well as N- and C- sequences flanking it differ entirely from those of MUC1-TM. In vitro protein synthesis assays and extensive immunohistochemical as well as western blot analyses with MUC1-ARF specific monoclonal antibodies confirmed MUC1-ARF expression. Rather than being expressed at the cell membrane like MUC1-TM, immunostaining showed that MUC1-ARF protein localizes mainly in the nucleus: Immunohistochemical analyses of MUC1-expressing tissues demonstrated MUC1-ARF expression in the nuclei of secretory luminal epithelial cells. MUC1-ARF expression varies in different malignancies. While the malignant epithelial cells of pancreatic cancer show limited expression, in breast cancer tissue MUC1-ARF demonstrates strong nuclear expression. Proinflammatory cytokines upregulate expression of MUC1-ARF protein and co-immunoprecipitation analyses demonstrate association of MUC1-ARF with SH3 domain-containing proteins. Mass spectrometry performed on proteins coprecipitating with MUC1-ARF demonstrated Glucose-6-phosphate 1-dehydrogenase (G6PD) and Dynamin 2 (DNM2). These studies not only reveal that the MUC1 gene generates a previously unidentified MUC1-ARF protein, they also show that just like its ‘parent’ MUC1-TM protein, MUC1-ARF is apparently linked to signaling and malignancy, yet a definitive link to these processes and the roles it plays awaits a precise identification of its molecular functions. Comprising at least 524 amino acids, MUC1-ARF is, furthermore, the longest ARF protein heretofore described.

Intra- and Extra-Cellular Events Related to Altered Glycosylation of MUC1 Promote Chronic Inflammation, Tumor Progression, Invasion, and Metastasis

Altered glycosylation of mucin 1 (MUC1) on tumor cells compared to normal epithelial cells was previously identified as an important antigenic modification recognized by the immune system in the process of tumor immunosurveillance. This tumor form of MUC1 is considered a viable target for cancer immunotherapy. The importance of altered MUC1 glycosylation extends also to its role as a promoter of chronic inflammatory conditions that lead to malignant transformation and cancer progression. We review here what is known about the role of specific cancer-associated glycans on MUC1 in protein-protein interactions and intracellular signaling in cancer cells and in their adhesion to each other and the tumor stroma. The tumor form of MUC1 also creates a different landscape of inflammatory cells in the tumor microenvironment by controlling the recruitment of inflammatory cells, establishing specific interactions with dendritic cells (DCs) and macrophages, and facilitating tumor escape from the immune system. Through multiple types of short glycans simultaneously present in tumors, MUC1 acquires multiple oncogenic properties that control tumor development, progression, and metastasis at different steps of the process of carcinogenesis.

Review of STAT3 (Signal Transducers and Activators of Transcription) in head and neck cancer

STATs can be activated independently of JAKs, most notably by c-Src kinases. In cancer cells, STAT3 and STAT5 activation leads to the increased expression of downstream target genes, leading to increased cell proliferation, cell survival, angiogenesis, and immune system evasion. STAT3 and STAT5 are expressed and activated in head and neck squamous cell carcinoma where they contribute to cell survival and proliferation. STATs can be activated by a number of signal transduction pathways, including the epidermal growth factor receptor (EGFR), nicotinic receptor, interleukin (IL) receptor, and erythropoietin receptor pathways. Identifying agents that inhibit STAT-3, a cytosolic transcription factor involved in the activation of various genes implicated in tumor progression is a promising strategy for cancer chemoprevention. Several approaches have been used to inhibit STAT3 in the hope of developing an antitumor agent. Although several STAT3-specific agents are promising, none are in clinical development, mostly because of drug delivery and stability issues.

Photothermal therapeutic response of cancer cells to aptamer-gold nanoparticle-hybridized graphene oxide under NIR illumination

The objective of this study was to synthesize a nanocomposite, aptamer-gold nanoparticle-hybridized graphene oxide (Apt-AuNP-GO), to facilitate targeted treatment of tumor cells by near-infrared (NIR) light-activatable photothermal therapy. We also investigated whether Apt-AuNP-GO with NIR illumination modulates heat shock proteins (HSPs) expression leading to therapeutic response in human breast cancer cells. These findings can provide strategies for improving the photothermal therapy efficacy of cancer. The self-assembled Apt-AuNP-GO nanocomposite could selectively target MUC1-positive human breast cancer cells (MCF-7) due to the specific interaction between the MUC1-binding-aptamer and the MUC1 (type I transmembrane mucin glycoprotein) on cell membrane. In addition, Apt-AuNP-GO has a high light-to-heat conversion capability for photoabsorption of NIR light, and it is able to exert therapeutic effects on MCF-7 cells at an ultralow concentration without inducing adverse effects in healthy cells. The Apt-AuNP-GO nanocomposites combine the advantages of GOs, AuNPs, and Apts, possess specific targeting capability, excellent biocompatibility, and tumor cell destruction ability, suggesting great potential for application in the photothermal therapy of breast cancer. Under NIR illumination, Apt-AuNP-GO induced transient increase in HSP70 expression, which decreased thereafter. This phenomenon may cause irreversible damage to Apt-AuNP-GO-treated MCF-7 cell under NIR illumination. We also demonstrated that the combination therapy of heat and HSP70 inhibitor could synergistically generate marked tumoricidal effects against breast cancer. These results suggest that the degree and duration of HSP70 protein expression are correlated with therapeutic effects against breast cancer for Apt-AuNP-GO-assisted photothermal therapy. We believe that such a nanocomposite can be readily extended to the construction of HSP70 inhibitors-loaded Apt-AuNP-GO, which could deliver both heat and HSP70 inhibitors to tumorigenic regions for the chemo-photothermal therapy.

15-Lipoxygenase-1 suppression of colitis-associated colon cancer through inhibition of the IL-6/STAT3 signaling pathway

The IL-6/signal transducer and activator of transcription 3 (STAT3) pathway is a critical signaling pathway for colitis-associated colorectal cancer (CAC). Peroxisome proliferator-activated receptor (PPAR)-δ, a lipid nuclear receptor, up-regulates IL-6. 15-Lipoxygenase-1 (15-LOX-1), which is crucial to production of lipid signaling mediators to terminate inflammation, down-regulates PPAR-δ. 15-LOX-1 effects on IL-6/STAT3 signaling and CAC tumorigenesis have not been determined. We report that intestinally targeted transgenic 15-LOX-1 expression in mice inhibited azoxymethane- and dextran sodium sulfate-induced CAC, IL-6 expression, STAT3 phosphorylation, and IL-6/STAT3 downstream target (Notch3 and MUC1) expression. 15-LOX-1 down-regulation was associated with IL-6 up-regulation in human colon cancer mucosa. Reexpression of 15-LOX-1 in human colon cancer cells suppressed IL-6 mRNA expression, STAT3 phosphorylation, IL-6 promoter activity, and PPAR-δ mRNA and protein expression. PPAR-δ overexpression in colonic epithelial cells promoted CAC tumorigenesis in mice and increased IL-6 expression and STAT3 phosphorylation, whereas concomitant 15-LOX-1 expression in colonic epithelial cells (15-LOX-1-PPAR-δ-Gut mice) suppressed these effects: the number of tumors per mouse (mean ± sem) was 4.22 ± 0.68 in wild-type littermates, 6.67 ± 0.83 in PPAR-δ-Gut mice (P = 0.026), and 2.25 ± 0.25 in 15-LOX-1-PPAR-δ-Gut mice (P = 0.0006). Identification of 15-LOX-1 suppression of PPAR-δ to inhibit IL-6/STAT3 signaling-driven CAC tumorigenesis provides mechanistic insights that can be used to molecularly target CAC.

MUC1 extracellular domain confers resistance of epithelial cancer cells to anoikis

Anoikis, a special apoptotic process occurring in response to loss of cell adhesion to the extracellular matrix, is a fundamental surveillance process for maintaining tissue homeostasis. Resistance to anoikis characterises cancer cells and is a pre-requisite for metastasis. This study shows that overexpression of the transmembrane mucin protein MUC1 prevents initiation of anoikis in epithelial cancer cells in response to loss of adhesion. We show that this effect is largely attributed to the elongated and heavily glycosylated extracellular domain of MUC1 that protrudes high above the cell membrane and hence prevents activation of the cell surface anoikis-initiating molecules such as integrins and death receptors by providing them a mechanically ‘homing' microenvironment. As overexpression of MUC1 is a common feature of epithelial cancers and as resistance to anoikis is a hallmark of both oncogenic epithelial–mesenchymal transition and metastasis, MUC1-mediated cell resistance to anoikis may represent one of the fundamental regulatory mechanisms in tumourigenesis and metastasis.

STAT3 Target Genes Relevant to Human Cancers

Since its discovery, the STAT3 transcription factor has been extensively studied for its function as a transcriptional regulator and its role as a mediator of development, normal physiology, and pathology of many diseases, including cancers. These efforts have uncovered an array of genes that can be positively and negatively regulated by STAT3, alone and in cooperation with other transcription factors. Through regulating gene expression, STAT3 has been demonstrated to play a pivotal role in many cellular processes including oncogenesis, tumor growth and progression, and stemness. Interestingly, recent studies suggest that STAT3 may behave as a tumor suppressor by activating expression of genes known to inhibit tumorigenesis. Additional evidence suggested that STAT3 may elicit opposing effects depending on cellular context and tumor types. These mixed results signify the need for a deeper understanding of STAT3, including its upstream regulators, parallel transcription co-regulators, and downstream target genes. To help facilitate fulfilling this unmet need, this review will be primarily focused on STAT3 downstream target genes that have been validated to associate with tumorigenesis and/or malignant biology of human cancers.

Genetic regulation of MUC1 expression by Helicobacter pylori in gastric cancer cells

Helicobacter pylori infection of the stomach is associated with the development of gastritis, peptic ulcers, and gastric adenocarcinomas, but the mechanisms are unknown. MUC1 is aberrantly overexpressed by more than 50% of stomach cancers, but its role in carcinogenesis remains to be defined. The current studies were undertaken to identify the genetic mechanisms regulating H. pylori-dependent MUC1 expression by gastric epithelial cells. Treatment of AGS cells with H. pylori increased MUC1 mRNA and protein levels, and augmented MUC1 gene promoter activity, compared with untreated cells. H. pylori increased binding of STAT3 and MUC1 itself to the MUC1 gene promoter within a region containing a STAT3 binding site, and decreased CpG methylation of the MUC1 promoter proximal to the STAT3 binding site, compared with untreated cells. These results suggest that H. pylori upregulates MUC1 expression in gastric cancer cells through STAT3 and CpG hypomethylation.

Targeting the STAT3 signaling pathway in cancer: role of synthetic and natural inhibitors

Signal transducers and activators of transcription (STATs) comprise a family of cytoplasmic transcription factors that mediate intracellular signaling that is usually generated at cell surface receptors and thereby transmit it to the nucleus. Numerous studies have demonstrated constitutive activation of STAT3 in a wide variety of human tumors, including hematological malignancies (leukemias, lymphomas, and multiple myeloma) as well as diverse solid tumors (such as head and neck, breast, lung, gastric, hepatocellular, colorectal and prostate cancers). There is strong evidence to suggest that aberrant STAT3 signaling promotes initiation and progression of human cancers by either inhibiting apoptosis or inducing cell proliferation, angiogenesis, invasion, and metastasis. Suppression of STAT3 activation results in the induction of apoptosis in tumor cells, and accordingly its pharmacological modulation by tyrosine kinase inhibitors, antisense oligonucleotides, decoy nucleotides, dominant negative proteins, RNA interference and chemopreventive agents have been employed to suppress the proliferation of various human cancer cells in culture and tumorigenicity in vivo. However, the identification and development of novel drugs that can target deregulated STAT3 activation effectively remains an important scientific and clinical challenge. This review presents the evidence for critical roles of STAT3 in oncogenesis and discusses the potential for development of novel cancer therapies based on mechanistic understanding of STAT3 signaling cascade.

High expression of interleukin-22 and its receptor predicts poor prognosis in pancreatic ductal adenocarcinoma

BACKGROUND

The cytokine interleukin-22 (IL-22) and its receptor are present in the tumor microenvironment. Their function in pancreatic ductal adenocarcinoma (PDAC) remains largely unknown. The goal of the present study was to measure the expression of IL-22 and IL-22R in PDAC and assess their relationship with clinicopathological features and prognosis.

METHODS

The expression of IL-22 and IL-22R was evaluated by immunohistochemistry in PDAC tissues from 57 patients and by Western blotting in six tumors and adjacent nontumor tissues. A statistical analysis was conducted to assess the relationship between levels of expression, clinicopathological factors, and overall survival. In addition, the relationship between the expression of IL-22 and IL-22R and invasion was assessed by Western blotting and transwell assay with the PDAC cell lines PANC1 and BxPC3.

RESULTS

Positive IL-22 staining was detected in PDAC tissues and adjacent nontumor tissues. Positive IL-22R staining was detected in PDAC cells. High expression of IL-22 and IL-22R correlated significantly with lymph node involvement. IL-22 increased the phosphorylation of signal transducer and activator of transcription3, the expression of matrix metalloproteinase 9, and the invasion in PANC1 and BxPC3 cells in vitro while silencing of IL-22R RNA caused opposite effects. Most importantly, overall survival was significantly poorer in patients with high expression of IL-22 and IL-22R than in those with low expression.

CONCLUSIONS

These findings reveal the positive role of IL-22 and IL-22R in invasion and metastasis in human PDAC. IL-22 and IL-22R may be suitable independent prognostic markers in PDAC.

MUC1 and metastatic cancer: expression, function and therapeutic targeting

MUC1 is a transmembrane mucin that is often overexpressed in metastatic cancers and often used as a diagnostic marker for metastatic progression. The extracellular domain of MUC1 can serve as a ligand for stromal and endothelial cell adhesion receptors, and the cytoplasmic domain engages in several interactions that can result in increased migration and invasion, as well as survival. In this review, we address the role of MUC1 in metastatic progression by assessing clinical studies reporting MUC1 levels at various disease stages, reviewing mouse models utilized to study the role of MUC1 in metastatic progression, discuss mechanisms of MUC1 upregulation, and detail MUC1 protein interactions and signaling events. We review interactions between MUC1 and the extracellular environment, with proteins colocalized in the plasma membrane and/or cytoplasmic proteins, and summarize the role of MUC1 in the nucleus as a transcriptional cofactor. Finally, we review recent publications describing current therapies targeting MUC1 in patients with advanced disease and the stage of these therapies in preclinical development or clinical trials.

Emerging molecular targets in melanoma invasion and metastasis

Metastatic cutaneous melanoma accounts for the majority of skin cancer deaths due to its aggressiveness and high resistance to current therapies. To efficiently metastasize, invasive melanoma cells need to change their cytoskeletal organization and alter contacts with the extracellular matrix and the surrounding stromal cells. Melanoma cells can use different migratory strategies depending on varying environments to exit the primary tumour mass and invade surrounding and later distant tissues. In this review, we have focused on tumour cell plasticity or the interconvertibility that melanoma cells have as one of the factors that contribute to melanoma metastasis. This has been an area of very intense research in the last 5 yr yielding a vast number of findings. We have therefore reviewed all the possible clinical opportunities that this new knowledge offers to both stratify and treat cutaneous malignant melanoma patients.

Potential role of signal transducer and activator of transcription (STAT)3 signaling pathway in inflammation, survival, proliferation and invasion of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most lethal malignancies, and is also the fourth most common cancer worldwide with around 700,000 new cases each year. Currently, first line chemotherapeutic drugs used for HCC include fluorouracil, cisplatin, doxorubicin, paclitaxel and mitomycin, but most of these are non-selective cytotoxic molecules with significant side effects. Sorafenib is the only approved targeted therapy by the U.S. Food and Drug Administration for HCC treatment, but patients suffer from various kinds of adverse effects, including hypertension. The signal-transducer-and-activator-of-transcription 3 (STAT3) protein, one of the members of STATs transcription factor family, has been implicated in signal transduction by different cytokines, growth factors and oncogenes. In normal cells, STAT3 activation is tightly controlled to prevent dysregulated gene transcription, whereas constitutively activated STAT3 plays an important role in tumorigenesis through the upregulation of genes involved in anti-apoptosis, proliferation and angiogenesis. Thus, pharmacologically safe and effective agents that can block STAT3 activation have the potential both for the prevention and treatment of HCC. In the present review, we discuss the possible role of STAT3 signaling cascade and its interacting partners in the initiation of HCC and also analyze the role of various STAT3 regulated genes in HCC progression, inflammation, survival, invasion and angiogenesis.

MUC1-C oncoprotein as a target in breast cancer: activation of signaling pathways and therapeutic approaches

Mucin 1 (MUC1) is a heterodimeric protein formed by two subunits that is aberrantly overexpressed in human breast cancer and other cancers. Historically, much of the early work on MUC1 focused on the shed mucin subunit. However, more recent studies have been directed at the transmembrane MUC1-C-terminal subunit (MUC1-C) that functions as an oncoprotein. MUC1-C interacts with EGFR (epidermal growth factor receptor), ErbB2 and other receptor tyrosine kinases at the cell membrane and contributes to activation of the PI3KAKT and mitogen-activated protein kinase kinase (MEK)extracellular signal-regulated kinase (ERK) pathways. MUC1-C also localizes to the nucleus where it activates the Wnt/β-catenin, signal transducer and activator of transcription (STAT) and NF (nuclear factor)-κB RelA pathways. These findings and the demonstration that MUC1-C is a druggable target have provided the experimental basis for designing agents that block MUC1-C function. Notably, inhibitors of the MUC1-C subunit have been developed that directly block its oncogenic function and induce death of breast cancer cells in vitro and in xenograft models. On the basis of these findings, a first-in-class MUC1-C inhibitor has entered phase I evaluation as a potential agent for the treatment of patients with breast cancers who express this oncoprotein.

Androgen receptor regulates expression of the MUC1-C oncoprotein in human prostate cancer cells

BACKGROUND

The MUC1 heterodimeric oncoprotein is aberrantly overexpressed in human prostate cancers with more aggressive pathologic and clinical features. However, the signals that regulate MUC1 expression in prostate cancer cells are not well understood.

METHODS

MUC1 expression was studied in androgen-dependent and -independent prostate cancer cell lines by quantitative RT-PCR, immunoblotting and assessment of MUC1 promoter activation. Chromatin immunoprecipitation (ChIP) studies were performed to assess androgen receptor (AR) occupancy on the MUC1 promoter. Post-transcriptional regulation of MUC1 expression was assessed by miR-125b-mediated effects on activity of the MUC1 3' untranslated region (3'UTR).

RESULTS

The present studies demonstrate that AR occupies a consensus AR element on the MUC1 promoter in androgen-dependent LNCaP, but not in androgen-independent DU145 and PC3, prostate cancer cells. The results further show that AR downregulates MUC1 gene transcription. Stable introduction of exogenous AR in PC3 (PC3/AR) cells and then silencing of AR confirmed AR-mediated repression of the MUC1 promoter. AR signaling has also been shown to drive miR-125b expression. The present studies further demonstrate that miR-125b suppresses MUC1 translation in LNCaP cells and that an anti-sense miR-125b upregulates expression of MUC1 protein. In addition, stable expression of miR-125b in DU145 cells resulted in decreases in MUC1 levels.

CONCLUSIONS

These findings demonstrate that AR signaling regulates MUC1 expression by transcriptional and posttranscriptional mechanisms in prostate cancer cells.

ROCK and JAK1 signaling cooperate to control actomyosin contractility in tumor cells and stroma

Proinflammatory cytokines are frequently observed in the tumor microenvironment, and chronic inflammation is involved in cancer initiation and progression. We show that cytokine signaling through the receptor subunit GP130-IL6ST and the kinase JAK1 generates actomyosin contractility through Rho-kinase dependent signaling. This pathway generates contractile force in stromal fibroblasts to remodel the extracellular matrix to create tracks for collective migration of squamous carcinoma cells and provides the high levels of actomyosin contractility required for migration of individual melanoma cells in the rounded, "amoeboid" mode. Thus, cytokine signaling can generate actomyosin contractility in both stroma and tumor cells. Strikingly, actomyosin contractility itself positively modulates activity of the transcription factor STAT3 downstream of JAK1, demonstrating positive feedback within the signaling network.

MUC1-C oncoprotein promotes STAT3 activation in an autoinductive regulatory loop

Signal transducer and activator of transcription 3 (STAT3) is activated in human breast cancer and other malignancies. Mucin 1 (MUC1) is a heterodimeric cell surface glycoprotein that is overexpressed in human carcinomas and, like STAT3, promotes cell survival and induces transformation. We found that in breast cancer cells, the MUC1 carboxyl-terminal receptor subunit (MUC1-C) associates with the gp130-Janus-activated kinase 1 (JAK1)-STAT3 complex. The MUC1-C cytoplasmic domain interacted directly with JAK1 and STAT3, and MUC1-C was necessary for JAK1-mediated STAT3 activation. In turn, MUC1-C and activated STAT3 occupied the promoter of MUC1, and MUC1-C contributed to STAT3-mediated activation of MUC1 transcription. The MUC1-C inhibitor GO-201 blocked the MUC1-C interaction with STAT3, thereby decreasing MUC1-C and STAT3 occupancy on the MUC1 and STAT3 promoters and activation of STAT3 target genes, including MUC1 itself. These findings indicate that MUC1-C promotes STAT3 activation and that MUC1-C and STAT3 function in an autoinductive loop that may play a role in cancer cell survival.