EPH-EPHRIN in human gastrointestinal cancers

Advances and current concepts on Eph receptors and ephrins in upper digestive tract cancers

Erythropoietin-producing hepatocellular (Eph) receptors comprise the largest group of surface receptors and are responsible for cellular signals. Eph/ephrin signaling has been identified to play a role in key cancer development and progression processes, especially in the upper gastrointestinal tract. The Eph/ephrin system has been described as a tumor suppressor in duodenal cancer, while in esophageal, gastric, hepatic, and pancreatic cancer, the system has been related to tumor progression. For their significant role in developing a wide range of malignancies, Eph receptors and their ligands have proven to be an important target for new anticancer therapies. In this review, we present an overview of the literature and highlight evidence supporting the role of the Eph/ephrin system in upper digestive tract cancers. In addition, we discuss molecular findings that represent promising therapeutic targets for these cancers.

EphA10 and EphB3 are prognostic markers in gallbladder squamous cell/adenosquamous carcinomas and adenocarcinomas

AIMS

Squamous cell/adenosquamous carcinomas (SC/ASC) are rare subtypes of gallbladder cancers (GBCs). Clinical characteristics of SC/ASC have not been well documented, and no biological markers of GBC carcinogenesis, progression and prognosis are available.

METHODS

We detected EphA10 and EphB3 expression in 69 SC/ASCs and 146 adenocarcinomas (ACs) with EnVision immunohistochemistry.

RESULTS

The percentage of cases with a patient age of > 45 years, lymph node metastasis and invasion was significantly higher in the SCs/ASCs compared with the ACs (P < 0.05). The positive expression of EphA10 and negative expression of EphB3 were significantly higher in the cases of SC/ASC and AC than in chronic cholecystitis (P < 0.01). The positive expressions of EphA10 and negative expression of EphB3 were significantly higher in the cases of poorly differentiation, large tumor size, high TNM stage, lymph node metastasis, invasion and no resection (only biopsy) of SC/ASC and AC. The negative correlation was found between EphA10 and EphB3 expression in SC/ASC and AC (P < 0.01). The univariate Kaplan-Meier analysis showed that positive EphA10 and negative EphB3, differentiation, tumor size, TNM stage, lymph node metastasis, invasion and surgical curability, is closely associated with a decreased overall survival in SC/ASC and AC patients (P < 0.05 or P < 0.01). The multivariate Cox regression analysis identified that positive EphA10 and negative EphB3 expression are independent factors for a poor-prognosis in SC/ASC and AC patients. The AUC for EphA10 and EphB3 showed might have role for carcinogenesis and progression of SC/ASC and AC.

CONCLUSIONS

The present study indicates that positive EphA10 and negative EphB3 expression are closely associated with the pathogenesis, clinical, pathological and biological behaviors, and poor prognosis in gallbladder cancer.

Aberrant EphB/ephrin-B expression in experimental gastric lesions and tumor cells

AIM: To determine whether the expression profiles of EphB receptor and ephrin-B ligand can be used as markers for dysplastic/oncogenic transformation in gastric mucosa.

METHODS: The protein expression and localization of EphB and ephrin-B in normal, ulcerated regenerating, and dysplastic gastric mucosa were examined in a rat experimental model by immunolabeling, and mRNA expression was assessed in four human gastric carcinoma cell lines by reverse transcription-polymerase chain reaction.

RESULTS: Ephrin-B- and EphB-expressing regions were divided along the pit-gland axis in normal gastric units. EphB2 was transiently upregulated in the experimental ulcer, and its expression domain extended to gastric pits and/or the luminal surface where ephrin-B-expressing pit cells reside. EphB2, B3, and B4 and ephrin-B1 were coexpressed in the experimental gastric dysplasia, and more than one ligand-receptor pair was highly expressed in each of the gastric carcinoma cell lines.

CONCLUSION: Robust and stable coexpression of EphB and ephrin-B is a feature common to experimentally induced gastric dysplasia and human gastric carcinoma cell lines as compared to normal gastric and ulcerated regenerating epithelia. Thus, EphB/ephrin-B may be a useful marker combination for dysplastic/oncogenic transformation in gastric cancer.

EphA4 is a prognostic factor in gastric cancer

BACKGROUND

Erythropoietin-producing hepatocellular (Eph) receptor, consisting of a family of receptor tyrosine kinases, plays critical roles in tumour development and is considered an attractive target for cancer therapy.

METHODS

Tumour samples were obtained from 222 patients with gastric adenocarcinoma who underwent gastrectomy. The expressions of EphA2, EphA4, and ephrinA1 were evaluated immunohistochemically.

RESULTS

High expressions of EphA2, EphA4, and ephrinA1 significantly correlated with variables related to tumour progression, including the depth of invasion, metastatic lymph nodes, pathological stage, and distant metastasis or recurrent disease. High expressions of EphA2, EphA4, and ephrinA1 were significantly associated with poorer disease-specific survival (DSS; p < 0.001, p < 0.001, p = 0.026). On multivariate analysis, EphA4 was an independent prognostic factor of DSS (hazard ratio [HR], 2.3; 95% confidence interval [CI], 1.1-4.8; p = 0.028), and EphA2 tended to be a prognostic factor (HR, 2.4; 95% CI, 1.0-5.8; p = 0.050). In stage II and III cancer, EphA4 and EphA2 were both significantly associated with shorter survival (p = 0.007 and 0.019), but only EphA2 was an independent prognostic factor (HR, 2.6; 95% CI, 1.1-6.3; p = 0.039).

CONCLUSION

EphA4 may play important roles in tumor progression and outcomes in patients with gastric cancer.

Detection of kinase amplifications in gastric cancer archives using fluorescence in situ hybridization

To test the feasibility of using bacterial artificial chromosomes (BAC) containing kinases for pathological diagnosis using fluorescence in situ hybridization (FISH), 10 BAC probes containing a gene amplified in 5% or more of a pilot cohort were selected from a previous survey using arbitrarily selected BAC clones harboring 100 kinases. In this report, we describe the prevalence and association with the clinicopathological profile of these selected 10 BAC probes in 365 gastric cancer tissues. FISH analyses using these 10 BAC probes containing loci encoding EGFR, ERBB2(HER2), EPHB3, PIK3CA, MET, PTK7, ACK1, STK15, SRC, and HCK showed detectable amplifications in paraffin-embedded tissue in 2.83% to 13.6% of the gastric cancer tissues. Considerable numbers of the cases showed the co-amplification of two or more of the probes that were tested. BAC probes located within a genome neighborhood, such as PIK3CA, EPHB3, and ACK1 at 3q26-29 or HCK, SRC, and STK15 at 20q11-13.1, were often co-amplified in the same cases, but non-random co-amplifications of genes at distant genomic loci were also observed. These findings provide basic information regarding the creation of a strategy for personalizing gastric cancer therapy, especially when using multiple kinase inhibitors.

Polyphenol rich botanicals used as food supplements interfere with EphA2-ephrinA1 system

The Eph tyrosine kinase receptors and their ephrin ligands play a central role in several human cancers and their deregulated expression or function promotes tumorigenesis, inducing aggressive tumor phenotypes. Green tea extracts (GTE) have been recently found to inhibit Eph-kinase phosphorylation. In order to evaluate the potential contribution of edible and medicinal plants on EphA2-ephrinA1 modulation, 133 commercially available plant extracts used as food supplements, essential and fixed oils were screened with an ELISA-based binding assay. Nine plant extracts, rich of polyphenols, reversibly inhibited binding in a dose-dependent manner (IC₅₀ 0.83-24 μg/ml). Functional studies on PC3 prostate adenocarcinoma cells revealed that active extracts antagonized ephrinA1-Fc-induced EphA2-phosphorylation at non-cytotoxic concentrations (IC₅₀ 0.31-11.3 μg/ml) without interfering with EGF-induced EGFR activation, suggesting a specific effect. These findings could furnish an interesting starting point regarding the potential relationship between diet, edible plant secondary metabolites and Eph-ephrin system, suggesting their possible involvement in cancer development modulation.