Bile acids initiate lineage-addicted gastroesophageal tumorigenesis by suppressing the EGF receptor-AKT axis

Lack of Association between Epidermal Growth Factor or Its Receptor and Reflux Esophagitis, Barrett’s Esophagus, and Esophageal Adenocarcinoma: A Case-Control Study

The epidermal growth factor (EGF) and its receptor (EGFR) gene-gene interactions were shown to increase the susceptibility to esophageal cancer. However, the role of the EGF/EGFR pathway in the development of gastroesophageal reflux disease (GERD) and its complications (reflux esophagitis (RE), Barrett's esophagus (BE), and esophageal adenocarcinoma (EAC)) remains unclear. This association study is aimed at investigating functional EGF and EGFR gene polymorphisms, their mRNA expression in esophageal tissues, and EGF plasma levels in relation to RE, BE, and EAC development in the Central European population. 301 patients with RE/BE/EAC (cases) as well as 98 patients with nonerosive reflux disease (NERD) and 8 healthy individuals (controls) were genotyped for +61 A>G EGF (rs4444903) and +142285 G>A EGFR (rs2227983) polymorphisms using the TaqMan quantitative polymerase chain reaction (qPCR). In random subgroups, the EGF and EGFR mRNA expressions were analyzed by reverse transcription qPCR in esophageal tissue with and without endoscopically visible pathological changes; and the EGF plasma levels were determined by enzyme-linked immunosorbent assay. None of the genotyped SNPs nor EGF-EGFR genotype interactions were associated with RE, BE, or EAC development (p > 0.05). Moreover, mRNA expression of neither EGF nor EGFR differed between samples of the esophageal tissue with and without endoscopically visible pathology (p > 0.05) nor between samples from patients with different diagnoses, i.e., RE, BE, or EAC (p > 0.05). Nevertheless, the lower EGF mRNA expression in carriers of combined genotypes AA +61 EGF (rs4444903) and GG +142285 EGFR (rs2227983; p < 0.05) suggests a possible direct/indirect effect of EGF-EGFR gene interactions on EGF gene expression. In conclusion, EGF and EGFR gene variants and their mRNA/protein expression were not associated with RE, BE or EAC development in the Central European population.

Receptor Guanylyl Cyclase C and Cyclic GMP in Health and Disease: Perspectives and Therapeutic Opportunities

Receptor Guanylyl Cyclase C (GC-C) was initially characterized as an important regulator of intestinal fluid and ion homeostasis. Recent findings demonstrate that GC-C is also causally linked to intestinal inflammation, dysbiosis, and tumorigenesis. These advances have been fueled in part by identifying mutations or changes in gene expression in GC-C or its ligands, that disrupt the delicate balance of intracellular cGMP levels and are associated with a wide range of clinical phenotypes. In this review, we highlight aspects of the current knowledge of the GC-C signaling pathway in homeostasis and disease, emphasizing recent advances in the field. The review summarizes extra gastrointestinal functions for GC-C signaling, such as appetite control, energy expenditure, visceral nociception, and behavioral processes. Recent research has expanded the homeostatic role of GC-C and implicated it in regulating the ion-microbiome-immune axis, which acts as a mechanistic driver in inflammatory bowel disease. The development of transgenic and knockout mouse models allowed for in-depth studies of GC-C and its relationship to whole-animal physiology. A deeper understanding of the various aspects of GC-C biology and their relationships with pathologies such as inflammatory bowel disease, colorectal cancer, and obesity can be leveraged to devise novel therapeutics.

Consistent expression of guanylyl cyclase-C in primary and metastatic gastrointestinal cancers

BACKGROUND

The transmembrane receptor guanylate cyclase-C (GCC) has been found to be expressed in colorectal cancers. However, limited data are available on GCC protein expression in non-colorectal gastrointestinal tumors and few studies have reported whether GCC protein expression was consistently preserved in synchronous primary and metastatic cancer tissues.

METHODS

GCC protein status was assessed by immunohistochemistry in tumor specimens from individuals (n = 627) with gastrointestinal tumors, including esophageal (n = 130), gastric (n = 276), pancreatic (n = 136), and colorectal (n = 85) primary and metastatic tumors. Tissue specimens consisted of tissue microarrays containing esophageal, gastric, pancreatic tumors, and whole-slide tissue sections from colorectal cancer patients with matching primary and metastatic tumors.

RESULT

Among the evaluated esophageal, gastric, and pancreatic tumors, the frequency of GCC positivity at the protein level ranged from 59% to 68%. GCC was consistently expressed in primary and matched/synchronous metastatic lesions of colorectal cancer tissues derived from the same patients.

CONCLUSION

This observational study demonstrated the protein expression of GCC across various gastrointestinal malignancies. In all cancer histotypes, GCC protein localization was observed predominantly in the cytoplasm compared to the membrane region of tumor cells. Consistent immunohistochemistry detection of GCC protein expression in primary colorectal cancers and in their matched liver metastases suggests that the expression of GCC is maintained throughout the process of tumor progression and formation of metastatic disease.

Bile acid induces MUC2 expression and inhibits tumor invasion in gastric carcinomas

PURPOSE

Bile acids might induce mucin expression and regulate tumor behavior in esophageal and colon cancers. However, little is known about the effect of bile acids on tumor invasiveness of gastric carcinoma (GC). The aim of the current study was to elucidate the mechanisms by which bile acids regulate tumor invasion in GC.

METHODS

We investigated bile acid-induced MUC2 expression and cell invasion and migration in the cultured GC cell lines, SNU-216, and MKN45. In addition, immunohistochemical analysis of MUC2 and Snail was performed on 389 archival paraffin-embedded tissues of GC to evaluate the correlation of their expression with prognosis.

RESULTS

Deoxycholic acid (DCA), a secondary bile acid, had no effect on the viability of SNU-216 and MKN45 GC cells at low concentrations (0-100 μM), but decreased viability at a higher concentration (200 μM). MKN45 cells showed higher MUC2 expression than SNU-216 cells under basal conditions. DCA treatment upregulated MUC2 mRNA expression in both SNU-216 and MKN45 cells. Expression of Snail and MMP9 was markedly decreased by DCA treatment, and E-cadherin expression was subsequently increased. DCA significantly inhibited invasion and migration of SNU-216 and MKN45 cells. In human GC, MUC2 expression showed a negative correlation with Snail expression (P = 0.021) and a significantly positive correlation with better prognosis (P = 0.023).

CONCLUSIONS

Taken together, our data suggest that DCA induced MUC2 expression in GC cells and inhibited tumor invasion and migration. Additionally, MUC2-expressing GCs showed low rates of Snail expression and were associated with a favorable prognosis.

MUC2 Expression Is Correlated with Tumor Differentiation and Inhibits Tumor Invasion in Gastric Carcinomas: A Systematic Review and Meta-analysis

Background:

While MUC2 is expressed in intestinal metaplasia and malignant lesions, the clinicopathological significance of MUC2 expression is not fully elucidated in gastric carcinoma (GC).

Methods:

The present study investigated the correlation between MUC2 expression and clinicopathological parameters in 167 human GCs. In addition, to confirm the clinicopathological significance of MUC2 expression, we performed a systematic review and meta-analysis in 1,832 GCs.

Results:

MUC2 expression was found in 58 of 167 GCs (34.7%). MUC2-expressing GC showed lower primary tumor (T), regional lymph node (N), and tumor node metastasis (TNM) stages compared with GCs without MUC2 expression (p=.001, p=.001, and p=.011, respectively). However, MUC2 expression was not correlated with Lauren’s classification and tumor differentiation. In meta-analysis, MUC2 expression was significantly correlated with differentiation and lower tumor stage (odds ratio [OR], 1.303; 95% confidence interval [CI], 1.020 to 1.664; p = .034 and OR, 1.352; 95% CI, 1.055 to 1.734; p = .017, respectively) but not with Lauren’s classification, pN stage, or pTNM stage.

Conclusions:

MUC2 expression was correlated with a lower tumor depth and lower lymph node metastasis in our study; the meta-analysis showed a correlation of MUC2 expression with tumor differentiation and lower tumor depth.

Role of epidermal growth factor receptor tyrosine kinase inhibitors in the treatment of esophageal carcinoma and the suggested mechanisms of action

Cumulative evidence indicates that epidermal growth factor receptor (EGFR) is one of the most commonly altered genes in human cancer, via overexpression, amplification and mutation. Targeted inhibition of EGFR activity suppresses signal transduction pathways which control tumor cell growth, proliferation and resistance to apoptosis. Small molecule tyrosine kinase inhibitors (TKIs) are among the most common EGFR-targeting agents and have been used clinically to treat various malignancies. This review discusses the mechanism of action and clinical data that are relevant to the use of EGFR-TKIs in the treatment of esophageal carcinoma. The clinical and basic scientific experience of these agents thus far have implications for the future of therapeutic targeting of EGFR.

Deoxycholic acid impairs glycosylation and fucosylation processes in esophageal epithelial cells

It is generally accepted that esophageal adenocarcinoma arises from a Barrett's metaplastic lesion. Altered glycoprotein expression has been demonstrated in tissue from patients with Barrett's esophagus and esophageal cancer but the mechanisms regarding such changes are unknown. The bile acid deoxycholic acid (DCA) alters many cell signaling pathways and is implicated in esophageal cancer progression. We have demonstrated that DCA disrupts Golgi structure and affects protein secretion and glycosylation processes in cell lines derived from normal squamous epithelium (HET-1A) and Barrett's metaplastic epithelium (QH). Cell surface expression of glycans was identified using carbohydrate-specific probes (wheat germ agglutinate, conconavalin A, peanut agglutinin, lithocholic acid and Ulex europaeus agglutinin) that monitored N-glycosylation, O-glycosylation and core fucosylation in resting and DCA-treated cells. DCA altered intracellular localization and reduced cell surface expression of N-acetyl-D-glucosamine, α-methyl-mannopyranoside (Man/Glc) and fucose in both cell lines. Furthermore, DCA reduced the expression of epithelial growth factor receptor and E-cadherin in a manner analogous to treatment of cells with the N-glycan biosynthesis inhibitor tunicamycin. This is the first study to identify an altered Golgi structure and glycomic profile in response to DCA in esophageal epithelial cells, a process which could potentially contribute to metaplasia, dysplasia and cancer of the esophagus.

Cholecystectomy as a risk factor for oesophageal adenocarcinoma

BACKGROUND

Owing to an increased risk of oesophageal bile exposure after cholecystectomy, an association with oesophageal adenocarcinoma is possible. There are some data in support of this hypothesis, and the aim of this study was to ascertain whether the association could be confirmed.

METHODS

A population-based cohort study was undertaken to compare the number of cases of oesophageal adenocarcinoma observed in a cohort of patients who have had a cholecystectomy in Sweden during 1965-2008 with the expected number, calculated from the entire Swedish population of corresponding age, sex and year. The risk of oesophageal adenocarcinoma was assessed by calculating the standardized incidence ratio (SIR) with 95 per cent confidence intervals.

RESULTS

The cholecystectomy cohort included 345 251 patients who were followed up for a mean of 15 years and contributed 4 854 969 person-years at risk. The total of 126 new cases of oesophageal adenocarcinoma was greater than expected (SIR 1.29, 1.07 to 1.53). The strength of the association between cholecystectomy and oesophageal adenocarcinoma tended to increase with longer follow-up after cholecystectomy. There was no association between cholecystectomy and oesophageal squamous cell carcinoma (SIR 0.93, 0.81 to 1.08), and in an unoperated cohort of 192 960 patients with gallstones no increased risk of oesophageal adenocarcinoma was identified (SIR 0.99, 0.71 to 1.35).

CONCLUSION

Cholecystectomy appears to be linked to an increased risk of oesophageal adenocarcinoma, but the absolute risk is small.