Activation of MUC1 mucin expression by bile acids in human esophageal adenocarcinomatous cells and tissues is mediated by the phosphatidylinositol 3-kinase

The Role of Mucin Expression in the Diagnosis of Oesophago-Gastric Cancer: A Systematic Literature Review

Survival in oesophago-gastric cancer (OGC) is poor due to early diagnostic challenges. Non-invasive risk stratification may identify susceptible patients with pre-malignant or benign disease. Following diagnostic confirmation with endoscopic biopsy, early OGC may be treated sooner. Mucins are transmembrane glycoproteins implicated in OGC with potential use as biomarkers of malignant transformation. This systematic review defines the role of mucins in OGC diagnosis. A literature search of MEDLINE, Web of Science, Embase and Cochrane databases was performed following PRISMA protocols for studies published January 1960-December 2022. Demographic data and data on mucin sampling and analysis methods were extracted. The review included 124 studies (n = 11,386 patients). Gastric adenocarcinoma (GAc) was the commonest OG malignancy (n = 101) followed by oesophageal adenocarcinoma (OAc, n = 24) and squamous cell carcinoma (OSqCc, n = 10). Mucins MUC1, MUC2, MUC5AC and MUC6 were the most frequently implicated. High MUC1 expression correlated with poorer prognosis and metastases in OSqCc. MUC2 expression decreases during progression from healthy mucosa to OAc, causing reduced protection from gastric acid. MUC5AC was upregulated, and MUC6 downregulated in GAc. Mucin expression varies in OGC; changes may be epigenetic or mutational. Profiling upper GI mucin expression in OGC, with pre-malignant, benign and healthy controls may identify potential early diagnostic biomarkers.

Long-Term Evaluation of Biliary Reflux on Esogastric Mucosae after One-Anastomosis Gastric Bypass and Esojejunostomy in Rats

BACKGROUND

One-anastomosis gastric bypass/mini-gastric bypass (OAGB/MGB) remains controversial because it may cause chronic biliary reflux (BR). The risk of developing esogastric cancer due to BR after OAGB/MGB is based on the results of experimental rat studies using esojejunostomy (EJ). The aim of this study was to analyze the potential long-term consequences of BR on the esogastric mucosae in OAGB/MGB-operated rats and to compare these results to those from the use of EJ.

METHODS

Wistar rats received OAGB/MGB (n = 16), EJ (n = 16), and sham (n = 8) operations. Mortality and weight changes were evaluated throughout the experiment. BR was measured using magnetic resonance imaging (MRI). Rats received follow-ups for 30 weeks. A double-blinded histological analysis was performed in the esogastric segments.

RESULTS

BR was diagnosed in OAGB/MGB and EJ rats using the MRI technique; no BR occurred in the sham group. After a 30-week follow-up, no incidences of dysplasia or cancer were observed in the three groups. Additionally, esophageal intestinal metaplasia and mucosal ulcerations were observed in 41.7% and 50% of EJ rats, respectively, and no incidences of these conditions were observed in OAGB/MGB and sham rats. The incidence of esophagitis was significantly higher and more severe in the EJ group compared to those in the OAGB/MGB and sham groups (EJ = 100%, OAGB/MGB = 16.7%, sham = 8.3%; p < 0.001).

CONCLUSIONS

After a 30-week follow-up period, OAGB/MGB rats did not develop any precancerous or cancerous lesions when more than 40% of EJ rats had intestinal metaplasia.

Preclinical Organotypic Models for the Assessment of Novel Cancer Therapeutics and Treatment

The immense costs in both financial terms and preclinical research effort that occur in the development of anticancer drugs are unfortunately not matched by a substantial increase in improved clinical therapies due to the high rate of failure during clinical trials. This may be due to issues with toxicity or lack of clinical effectiveness when the drug is evaluated in patients. Currently, much cancer research is driven by the need to develop therapies that can exploit cancer cell adaptations to conditions in the tumor microenvironment such as acidosis and hypoxia, the requirement for more-specific, targeted treatments, or the exploitation of 'precision medicine' that can target known genomic changes in patient DNA. The high attrition rate for novel anticancer therapies suggests that the preclinical methods used in screening anticancer drugs need improvement. This chapter considers the advantages and disadvantages of 3D organotypic models in both cancer research and cancer drug screening, particularly in the areas of targeted drugs and the exploitation of genomic changes that can be used for therapeutic advantage in precision medicine.

Current and future roles of mucins in cholangiocarcinoma-recent evidences for a possible interplay with bile acids

Cholangiocarcinoma (CCA) is rare but highly malignant tumour. The diagnosis is difficult due to its silent clinical character and the inefficiency of currently available diagnostic markers. An enhanced understanding of the molecular pathways involved in CCA carcinogenesis would herald targeted, individualized therapies, as well as new early diagnostic tool with improvement of patient survival. Recently, two mucin proteins, MUC4 and MUC5 have gained interest for their involvement in tumour growth and progression and possible use as diagnostic and prognostic cancer biomarkers. Moreover, a number of studies have demonstrated an association between biliary or serum bile acids (BAs) and some forms of cancers including CCA. More importantly, BAs have been shown to participate in tumour progression by inducing alterations in the expression of oncogenic mucins. This review summarizes the most important findings regarding the possible use of mucin glycoproteins and BAs in the diagnosis and prognostication of CCA and discuss evidences suggesting a role of BAs in regulating the expression of transmembrane and secreted mucins.

Clinical and prognostic significance of MUC1 expression in patients with esophageal squamous cell carcinoma after radical resection

BACKGROUND/AIM

To investigate the clinical and prognostic significance of MUC1 expression in patients with esophageal squamous cell carcinoma (ESCC) after radical resection.

MATERIALS AND METHODS

A total of 108 ESCC specimens were evaluated by reverse transcriptase-polymerase chain reaction (RT-PCR) to detect MUC1 at the mRNA level and were evaluated by immunohistochemistry (IHC) to detect MUC1 at the protein level.

RESULTS

MUC1 mRNA was found in 74 cases by RT-PCR and MUC1 protein expression was found by IHC in 70 cases. Both MUC1 mRNA and protein expression correlated with pT (<0.05), pN (P < 0.01), and pTNM (<0.01). The 5-year survival rates of the patients were 39.8%. In univariate analysis, the 5-year survival rate in the ESCC patients was significantly associated with pT (P < 0.01), pN (P < 0.01), pTNM stage (P < 0.01), and MUC1 mRNA and protein expression (P < 0.05). In multivariate analysis, pN and MUC1 expression were the independent relevant factors.

CONCLUSION

MUC1 expression can become a useful marker to predict poor prognostic factors for 5-year survival rate in patients with ESCC after radical resection.

Upregulation of mucin glycoprotein MUC1 in the progression to esophageal adenocarcinoma and therapeutic potential with a targeted photoactive antibody-drug conjugate

BACKGROUND

Mucin glycoprotein 1 (MUC1) is a glycosylated transmembrane protein on epithelial cells. We investigate MUC1 as a therapeutic target in Barrett's epithelium (BE) and esophageal adenocarcinoma (EA) and provide proof of concept for a light based therapy targeting MUC1.

RESULTS

MUC1 was present in 21% and 30% of significantly enriched pathways comparing BE and EA to squamous epithelium respectively. MUC1 gene expression was x2.3 and x2.2 higher in BE (p=<0.001) and EA (p=0.03). MUC1 immunohistochemical expression increased during progression to EA and followed tumor invasion. HuHMFG1 based photosensitive antibody drug conjugates (ADC) showed cell internalization, MUC1 selective and light-dependent cytotoxicity (p=0.0006) and superior toxicity over photosensitizer alone (p=0.0022).

METHODS

Gene set enrichment analysis (GSEA) evaluated pathways during BE and EA development and quantified MUC1 gene expression. Immunohistochemistry and flow cytometry evaluated the anti-MUC1 antibody HuHMFG1 in esophageal cells of varying pathological grade. Confocal microscopy examined HuHMFG1 internalization and HuHMFG1 ADCs were created to deliver a MUC1 targeted phototoxic payload.

CONCLUSIONS

MUC1 is a promising target in EA. Molecular and light based targeting of MUC1 with a photosensitive ADC is effective in vitro and after development may enable treatment of locoregional tumors endoscopically.

Bile acids-mediated overexpression of MUC4 via FAK-dependent c-Jun activation in pancreatic cancer

The majority of pancreatic cancer (PC) patients are clinically presented with obstructive jaundice with elevated levels of circulatory bilirubin and alkaline phosphatases. In the current study, we examined the implications of bile acids (BA), an important component of bile, on the pathophysiology of PC and investigated their mechanistic association in tumor-promoting functions. Integration of results from PC patient samples and autochthonous mouse models showed an elevated levels of BA (p < 0.05) in serum samples compared to healthy controls. Similarly, an elevated BA levels was observed in pancreatic juice derived from PC patients (p < 0.05) than non-pancreatic non-healthy (NPNH) controls, further establishing the clinical association of BA with the pathogenesis of PC. The tumor-promoting functions of BA were established by observed transcriptional upregulation of oncogenic MUC4 expression. Luciferase reporter assay revealed distal MUC4 promoter as the primary responsive site to BA. In silico analysis recognized two c-Jun binding sites at MUC4 distal promoter, which was biochemically established using ChIP assay. Interestingly, BA treatment led to an increased transcription and activation of c-Jun in a FAK-dependent manner. Additionally, BA receptor, namely FXR, which is also upregulated at transcriptional level in PC patient samples, was demonstrated as an upstream molecule in BA-mediated FAK activation, plausibly by regulating Src activation. Altogether, these results demonstrate that elevated levels of BA increase the tumorigenic potential of PC cells by inducing FXR/FAK/c-Jun axis to upregulate MUC4 expression, which is overexpressed in pancreatic tumors and is known to be associated with progression and metastasis of PC.

The MUC1 mucin regulates the tumorigenic properties of human esophageal adenocarcinomatous cells

MUC1 is a membrane-bound mucin known to participate in tumor proliferation. It has been shown that MUC1 pattern of expression is modified during esophageal carcinogenesis, with a progressive increase from metaplasia to adenocarcinoma. The principal cause of development of esophageal adenocarcinoma is gastro-esophageal reflux and MUC1 was previously shown to be up-regulated by several bile acids present in reflux. In this report, our aim was thus to determine whether MUC1 plays a role in biological properties of human esophageal cancer cells. For that, a stable MUC1-deficient esophageal cancer cell line was established using a shRNA approach. In vitro (proliferation, migration and invasion) and in vivo (tumor growth following subcutaneous xenografts in SCID mice) biological properties of MUC1-deficient cells were analyzed. Our results show that esophageal cancer cells lacking MUC1 were less proliferative and had decreased migration and invasion properties. These alterations were accompanied by a decreased activity of NFKB p65, Akt and MAPK (p44/42, JNK and p38) pathways. MCM6 and TSG101 tumor-associated markers were also decreased. Subcutaneous xenografts showed a significant decrease in tumor size when cells did not express MUC1. Altogether, the data indicate that MUC1 plays a key role in proliferative, migrating and invasive properties of esophageal cancer cells as well as in tumor growth promotion. MUC1 mucin appears thus as a good therapeutic target to slow down esophageal tumor progression.

Operatively induced chronic reflux in rats: a suitable model for studying esophageal carcinogenesis?

BACKGROUND

The mechanisms of esophageal reflux leading to esophageal adenocarcinoma (EA) remain poorly understood. This study appraises critically an operatively induced chronic reflux rat model.

METHODS

We randomized 108 Sprague-Dawley rats into 2 experimental groups; one was performing esophagoduodenal (ED) anastomosis with or without gastrectomy to induce duodeno-esophageal reflux (DER group; n = 63), and the other involved duodeno-gastro-esophageal reflux (DGER group; n = 45). Control groups included (i) Roux-en-Y esophagojejunal anastomosis, (ii) laparotomy alone, (iii) subtotal gastrectomy to induce duodenogastric reflux (DGR group), and (iv) the same procedure as in the DGER group plus proton pump inhibition (PPI group). The esophagus underwent histologic and molecular analyses.

RESULTS

The prevalence of Barrett's esophagus (BE), dysplasia, and EA in the experimental groups was 41%, 7%, and 11%, respectively. Histologic and molecular analyses in groups DER, DGER, and DGR suggested that BE occurred through de novo intestinal metaplasia and proximal migration of duodenal cells. No distant metastases were identified. The molecular characteristics of both BE and EA were similar to humans. BE was more common, and dysplasia and EA less frequent in the DER group when compared with the DGER group (44% vs 24% [P = .038] and 7% vs 25% [P = .012], respectively). Compared with the DGER group, carcinogenic sequence occurred less frequently in the PPI-treated group (P = .019).

CONCLUSION

Despite pathophysiologic differences with humans, the rat model of esophagoduodenostomy reproduces accurately histologic and molecular lesions in the carcinogenetic sequence of BE and allowed us to identify novel, tumor-associated proteins that may be potential biomarkers and new therapeutic targets in EA.

Preventing cancer by targeting abnormally expressed self-antigens: MUC1 vaccines for prevention of epithelial adenocarcinomas

Prophylactic vaccines based on tumor-associated antigens (TAAs) have elicited concerns due to their potential toxicity. Because TAAs are considered self-antigens, the prediction is that such vaccines will induce autoimmunity. While this has been observed in melanoma, where an antitumor immune response leads to vitiligo, autoimmunity has almost never been seen following vaccination with numerous other TAAs. We hypothesized that antigen choice determines outcome and have been working to identify TAAs whose expression differs between normal and tumor tissue, and thus could elicit antitumor immunity without autoimmunity. Studies on the epithelial TAA MUC1 have revealed that, compared to MUC1 on normal cells, tumors, premalignant lesions, and noncancerous pathologies affecting epithelial cells express abnormal MUC1, which is not a self-antigen but rather an abnormal disease-associated antigen (DAA). This distinction, which can be made for many known TAAs, has broad implications for the design and acceptance of preventative cancer vaccines.

Signaling pathways in the molecular pathogenesis of adenocarcinomas of the esophagus and gastroesophageal junction

Esophageal adenocarcinoma develops in response to severe gastroesophageal reflux disease through the precursor lesion Barrett esophagus, in which the normal squamous epithelium is replaced by a columnar lining. The incidence of esophageal adenocarcinoma in the United States has increased by over 600% in the past 40 years and the overall survival rate remains less than 20% in the community. This review highlights some of the signaling pathways for which there is some evidence of a role in the development of esophageal adenocarcinoma. An increasingly detailed understanding of the biology of this cancer has emerged recently, revealing that in addition to the well-recognized alterations in single genes such as p53, p16, APC, and telomerase, there are interactions between the components of the reflux fluid, the homeobox gene Cdx2, and the Wnt, Notch, and Hedgehog signaling pathways.

Cell culture models for studying the development of Barrett's esophagus: a systematic review

Background

Barrett’s esophagus (BE) is a premalignant condition caused by chronic gastroesophageal reflux. BE patients have an increased risk of developing esophageal adenocarcinoma (EAC). As many aspects of this condition are still unknown, there is a need for in vitro models to study BE development.

Aim

To review the literature on cell lines and incubation conditions for studying BE development.

Methods

A literature search was performed using PubMed, EMBASE and the Cochrane library, combining the words esophagus, cell line, culture, Barrett’s, bile, acid, exposure, reflux and adenocarcinoma.

Results

A wide range of cell lines and incubation conditions to study BE development have been reported. The most commonly used cell lines are derived from epithelium from patients with BE or EAC. A 25-minute incubation with 200 μM bile salts induced cell proliferation and Akt phosphorylation. However, increased CDX2 and MUC2 expression was only observed with longer incubations or higher bile salt concentrations. Two-hundred μM bile at pH 6 showed a higher toxicity to EAC cells than the same concentration at pH 7. Multiple 5-minute exposures with 200 μM bile at pH 4 or pH 7 increased CK8/18 and COX2 in BE epithelial cells.

Conclusions

Two-hundred μM conjugated primary or secondary bile salts at pH 4 for multiple short exposures is able to induce BE specific factors in BE cell lines. In SQ and EAC cell lines; however, higher concentrations of secondary bile salts for 8 h are needed to induce BE specific molecules. Due to the high variability in reported methods, it is difficult to determine the most effective in vitro setup for studying the development of BE.

Systematic review: the role of bile acids in the pathogenesis of gastro-oesophageal reflux disease and related neoplasia

BACKGROUND

Factors other than acid may play a role in gastro-oesophageal reflux disease (GERD) and its complications.

AIM

To assessed the role of bile acids in the pathogenesis of GERD, Barrett's oesophagus and Barrett's-related neoplasia.

METHODS

We conducted a systematic review of computerised bibliographic databases for original articles involving humans or human oesophageal tissue or cells that assessed exposure to or manipulation of bile acids. Outcomes assessed included GERD symptoms; gross oesophageal injury; Barrett's oesophagus and related neoplasia; and intermediate markers of inflammation, proliferation or neoplasia.

RESULTS

Eighty-three original articles were included. In in vivo studies, bile acids concentrations were higher in the oesophageal aspirates of patients with GERD than controls, and bile acids infusions triggered GERD symptoms, especially in high concentrations or in combination with acid. In ex vivo/in vitro studies, bile acids stimulated squamous oesophageal cells and Barrett's epithelial cells to produce inflammatory mediators (e.g., IL-8 and COX-2) and caused oxidative stress, DNA damage and apoptosis. They also induced squamous cells to change their gene expression pattern to resemble intestinal-type cells and caused Barrett's cells to increase expression of intestinal-type genes.

CONCLUSIONS

In aggregate, these studies suggest that bile acids may contribute to the pathogenesis of symptoms, oesophagitis and Barrett's metaplasia with related carcinogenesis in patients with GERD. However, all study results are not uniform and substantial differences in study parameters may explain at least some of this variation.

The membrane-bound mucins: From cell signalling to transcriptional regulation and expression in epithelial cancers

The membrane-bound mucins belong to an ever-increasing family of O-glycoproteins. Based on their structure and localization at the cell surface they are thought to play important biological roles in cell-cell and cell-matrix interactions, in cell signalling and in modulating biological properties of cancer cells. Among them, MUC1 and MUC4 mucins are best characterized. Their altered expression in cancer (overexpression in the respiratory, gastro-intestinal, urogenital and hepato-biliary tracts) indicates an important role for these membrane-bound mucins in tumour progression, metastasis, cancer cell resistance to chemotherapeutics drugs and as specific markers of epithelial cancer cells. Some mechanisms responsible for MUC1 and MUC4 role in tumour cell properties have been deciphered recently. However, much remains to be done in order to understand the molecular mechanisms and signalling pathways that control the expression of membrane-bound mucins during the different steps of tumour progression toward adenocarcinoma and evaluate their potential as prognostic/diagnostic markers and as therapeutic tools. In this review we focus on the molecular mechanisms and signalling pathways known to control the expression of membrane-bound mucins in cancer. We will discuss the mechanisms of regulation at the promoter level (including genetic and epigenetic modifications) that may be responsible for the mucin altered pattern of expression in epithelial cancers.

Apoptosis and modulation of cell cycle control by bile acids in human leukemia T cells

Depending on the nature of chemical structures, different bile acids exhibit distinct biological effects. Their therapeutic efficacy has been widely demonstrated in various liver diseases, suggesting that they might protect hepatocytes against common mechanisms of liver damage. Although it has been shown to prevent apoptotic cell death in certain cell lines, bile acids significantly inhibited cell growth and induced apoptosis in cancer cells. To better understand the pharmacological potential of bile acids in cancer cells, we investigated and compared the effects of deoxycholic acid (DCA), ursodeoxycholic acid (UDCA), and their taurine-derivatives [taurodeoxycholic acid (TDCA) and tauroursodeoxycholic acid (TUDCA), respectively] on the induction of apoptosis and inhibition of cell proliferation of a human T leukemia cell line (Jurkat cells). All the bile acids tested induced a delay in cell cycle progression. Moreover, DCA markedly increased the fraction of apoptotic cells. The effects of TDCA, UDCA, and TUDCA were different from those observed for DCA. Their primary effect was the induction of necrosis. These distinctive features suggest that the hydrophobic properties of DCA play a role in its cytotoxic potential and indicate that it is possible to create new drugs useful for cancer therapy from bile acid derivatives as lead compounds.

MUC1, a new hypoxia inducible factor target gene, is an actor in clear renal cell carcinoma tumor progression

The hypoxia inducible factor (HIF) signaling pathway is known as the main renal carcinogenetic pathway. MUC1, an O-glycoprotein membrane-bound mucin, is overexpressed in clear renal cell carcinomas (cRCC) with correlation to two major prognostic factors: tumor-node-metastasis stage and nuclear Fürhman grade. We questioned whether there is a direct link between the HIF pathway and MUC1 overexpression in renal tumors. Interestingly, we observed concomitant increase of HIF-1alpha and MUC1 in metastatic cRCC group versus nonmetastatic cRCC group. Using different renal cell models and small interfering RNA assays targeting either HIF-1alpha or YC-1, a HIF-1 pharmacologic inhibitor, we showed induction of MUC1 expression under hypoxia by a HIF-dependent mechanism. Chromatin immunoprecipitation assay showed a direct binding of HIF-1alpha at the MUC1 promoter. In addition, combined site-directed mutagenesis and gel shift assay allowed the identification of two functional putative hypoxia responsive elements at -1488/-1485 and at -1510/-1507 in the promoter. Using a rat kidney model of ischemia/reperfusion, we confirmed in vivo that clamping renal pedicle for 1 hour followed by 2 hours of reperfusion induced increased MUC1 expression. Furthermore, MUC1 knockdown induced significant reduction of invasive and migration properties of renal cancer cells under hypoxia. Altogether, these results show that MUC1 is directly regulated by HIF-1alpha and affects the invasive and migration properties of renal cancer cells. Thus, MUC1 could serve as a potential therapeutic target in cRCC.

Deoxycholic acid induces the overexpression of intestinal mucin, MUC2, via NF-kB signaling pathway in human esophageal adenocarcinoma cells

Background

Mucin alterations are a common feature of esophageal neoplasia, and alterations in MUC2 mucin have been associated with tumor progression in the esophagus. Bile acids have been linked to esophageal adenocarcinoma and mucin secretion, but their effects on mucin gene expression in human esophageal adenocarcinoma cells is unknown.

Methods

Human esophageal adenocarcinoma cells were treated 18 hours with 50–300 μM deoxycholic acid, chenodeoxycholic acid, or taurocholic acid. MUC2 transcription was assayed using a MUC2 promoter reporter luciferase construct and MUC2 protein was assayed by Western blot analysis. Transcription Nuclear factor-κB activity was measured using a Nuclear factor-κB reporter construct and confirmed by Western blot analysis for Nuclear factor-κB p65.

Results

MUC2 transcription and MUC2 protein expression were increased four to five fold by bile acids in a time and dose-dependent manner with no effect on cell viability. Nuclear factor-κB activity was also increased. Treatment with the putative chemopreventive agent aspirin, which decreased Nuclear factor-κB activity, also decreased MUC2 transcription. Nuclear factor-κB p65 siRNA decreased MUC2 transcription, confirming the significance of Nuclear factor-κB in MUC2 induction by deoxycholic acid. Calphostin C, a specific inhibitor of protein kinase C (PKC), greatly decreased bile acid induced MUC2 transcription and Nuclear factor-κB activity, whereas inhibitors of MAP kinase had no effect.

Conclusion

Deoxycholic acid induced MUC2 overexpression in human esophageal adenocarcinoma cells by activation of Nuclear factor-κB transcription through a process involving PKC-dependent but not PKA, independent of activation of MAP kinase.

Analysis of mucins: role in laboratory diagnosis

Mucins are high molecular weight glycoproteins with complex oligosaccharide side chains attached to the apomucin protein backbone byO-glycosidic linkage; they are found in crude mucus gels that protect epithelial surfaces in the major tracts of the body and as transmembrane proteins expressed on the apical cell surface of glandular and ductal epithelia of various organs. Changes in the sequence of glycosylation of mucins in different settings generate a variety of epitopes in the oligosaccharide side chains of mucins, including newly expressed blood-group antigens, distinguishing between normal and diseased states. Tumour-associated epitopes on mucins and their antigenicity make them suitable as immunotargets on malignant epithelial cells and their secretions, creating a surge of interest in mucins as diagnostic and prognostic markers for various diseases, and even influencing the design of mucin-based vaccines. This review discusses the emerging roles of mucins such as MUC1 and MUC4 in cancer and some other diseases, and stresses how underglycosylated and truncated mucins are exploited as markers of disease and to monitor widespread metastasis, making them useful in patient management. Furthermore the type, pattern and amount of mucin secreted in some tissues have been considered in the classification and terminology of neoplasia and in specific organs such as the pancreas. These factors have been instrumental in pathological classification, diagnosis and prognostication of neoplasia.