Erythropoietin-producing human hepatocellular receptors (EPHs) compose the largest known subfamily of receptor tyrosine kinases (RTKs). They bind and interact with the EPH family receptor interacting proteins (ephrins). EPHs/ephrins are implicated in a variety of physiological processes, as well as in cancer pathogenesis. With neoplastic disease remaining a leading cause of death world-wide, the development of novel biomarkers aiding in the field of diagnosis, prognosis, and disease monitoring is of utmost importance. A multitude of studies have proven the association between the expression of members of the EPH/ephrin system and various clinicopathological parameters, including disease stage, tumor histologic grade, and patients’ overall survival. Besides their utilization in timely disease detection and assessment of outcome, EPHs/ephrins could also represent possible novel therapeutic targets. The aim of the current review of the literature was to present the existing data regarding the association between EPH/ephrin system expression and the clinical characteristics of malignant tumors.

Farnesoid X Receptor (FXR), a nuclear receptor superfamily member, is related with bile acids, glucose and lipids metabolism and recently with cancer. In the present study the clinical significance of FXR expression in invasive breast carcinoma was evaluated. FXR protein expression was assessed immunohistochemically on paraffin-embedded breast cancer tissues obtained from 115 breast cancer patients and was statistically analyzed with clinicopathological parameters, estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) expression, as well as with tumor cells' proliferative capacity and overall and disease-free patients' survival. FXR positivity was noted in 91 (79.1%) and high FXR expression in 51 (44.3%) out of 115 invasive breast carcinoma cases. High FXR expression was significantly associated with smaller tumor size (p=0.0318) and increased tumor cells' proliferative rate (p=0.0375). Invasive breast carcinoma patients presenting high FXR expression showed significantly longer overall and disease-free survival times compared to those with low FXR expression (log-rank test, p=0.0052 and p=0.0058). In multivariate analysis, FXR expression was identified as independent prognostic factor of overall and disease-free patients' survival (Cox-regression analysis, p=0.0023 and p=0.0049, respectively). The present data support evidence that FXR may be implicated at the earlier stage of breast malignant disease progression, being a strong and independent prognosticator of favorable overall and disease-free survival in invasive breast carcinoma.

Hu-antigen R (HuR) is considered to play a crucial role in tumor formation and growth by binding to mRNAs encoding proteins such as Cyclooxygenase-2 (COX-2) and inducing their expression via mRNA stabilization and/or altered translation. The present study aimed to evaluate the clinical significance of HuR and COX-2 proteins’ expression in human benign and malignant thyroid lesions. HuR and COX-2 proteins’ expression was assessed immunohistochemically on paraffin-embedded thyroid tissues obtained from 98 patients with benign (n = 48) and malignant (n = 50) lesions and was statistically analyzed with clinicopathological parameters, follicular cells’ proliferative capacity and recurrence risk rate. Enhanced HuR and COX-2 expression was significantly more frequently observed in malignant compared to benign thyroid lesions (p = 0.0073 and p = 0.0016, respectively), as well as in papillary carcinomas compared to hyperplastic nodules (p = 0.0039 and p = 0.0009, respectively). Positive associations of both HuR and COX-2 expression with follicular cells’ proliferation rate were also noted (p = 0.0087 and p = 0.0127, respectively). In malignant thyroid lesions, elevated COX-2 expression was significantly associated with female patients’ gender (p = 0.0381) and the presence of lymph node metastases (p = 0.0296). The present data support evidence that both HuR and COX-2 may be involved in the malignant state of thyroid neoplasia and may be utilized in the diagnosis of malignant thyroid tumors.

Hu-antigen R (HuR), a RNA-binding protein, is considered to play a crucial role in tumor development and progression by stabilizing or regulating a group of cellular mRNAs of cancer-related genes, such as cyclooxygenase-2 (COX-2). The present study aimed to evaluate the clinical significance of HuR and COX-2 expression in invasive breast carcinoma. HuR and COX-2 protein expression was assessed immunohistochemically on paraffin-embedded breast cancer tissue sections obtained from 121 patients and was statistically analyzed with clinicopathological parameters, estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), as well as with tumor cells' proliferative capacity and overall and disease-free patients' survival. High HuR expression was positively associated with larger tumor size and advanced disease stage (p = 0.0234 and p = 0.0361, respectively), being more frequently observed in ER negative cases (p = 0.0208). High COX-2 expression was negatively associated with histological (p < 0.0001) and nuclear (p = 0.0033) grade and tumor cells' proliferative rate (p = 0.0015), being more frequently observed in luminal-A compared to other molecular subtypes (p = 0.0221). High HuR expression was associated with poor overall and disease-free patients' survival at both univariate (log-rank test, p = 0.0092 and p = 0.0004, respectively) and multivariate (Cox-regression analysis, p = 0.0223 and p = 0.0004, respectively) level. On the other hand, high COX-2 expression was associated with favorable overall and disease-free patients' survival merely at univariate level (log-rank test, p = 0.0389 and p = 0.0154, respectively). HuR expression was not associated with COX-2 expression (Spearman R = 0.1489, p = 0.1032). The present data support evidence that HuR is associated with tumor aggressiveness and poor prognosis in breast carcinoma, reinforcing its potential as promising therapeutic target in this type of neoplasia.

Ongoing research continues to elucidate the complex role of ephrin receptors (EPHs) and their ligands (ephrins) in breast cancer pathogenesis, with their varying expression patterns implied to have an important impact on patients’ outcome. The current study aims to investigate the clinical significance of EPHA2, EPHA4, and EPHA7 expression in triple-negative breast cancer (TNBC) cases. EPHA2, EPHA4, and EPHA7 protein expression was assessed immunohistochemically on formalin-fixed and paraffin-embedded (FFPE) TNBC tissue sections from 52 TNBC patients and correlated with key clinicopathologic parameters and patients’ survival data (overall survival (OS); disease-free survival (DFS)). EPHA2, EPHA4, and EPHA7 expression was further examined in TNBC cell lines. EPHA2 overexpression was observed in 26 (50%) of the TNBC cases, who exhibited a shorter OS and DFS than their low-expression counterparts, with EPHA2 representing an independent prognostic factor for OS and DFS (p = 0.0041 and p = 0.0232, respectively). EPHA4 overexpression was associated with lymph node metastasis in TNBC patients (p = 0.0546). Alterations in EPHA2, EPHA4, and EPHA7 expression levels were also noted in the examined TNBC cell lines. Our study stresses that EPHA2 expression constitutes a potential prognostic factor for TNBC patients. Given the limited treatment options and poorer outcome that accompany the TNBC subtype, EPHA2 could also pose as a target for novel, more personalized, and effective therapeutic approaches for those patients.