EpCAM is up-regulated by EGF via ERK1/2 signaling and suppresses human epithelial ovarian cancer cell migration

Clinicopathological and prognostic value of epithelial cell adhesion molecule in solid tumours: a meta-analysis

Background

Malignant tumors, mainly solid tumors, are a significant obstacle to the improvement of life expectancy at present. Epithelial cell adhesion molecule (EpCAM), a cancer stem cell biomarker, showed widespread expression in most normal epithelial cells and most cancers. Although the clinical significance of EpCAM in various malignant solid tumors has been studied extensively, the latent relationships between EpCAM and pathological and clinical characteristics in solid tumors and differences in the roles of EpCAM among tumors have not been clearly determined. The destination point of this study was to analyze the value of EpCAM in solid tumors in clinicopathological and prognostic dimension using a meta-analysis approach.

Method and materials

A comprehensive and systematic search of the researches published up to March 7th, 2022, in PubMed, EMBASE, Web of Science, Cochrane library and PMC databases was performed. The relationships between EpCAM overexpression, clinicopathological characteristics, and survival outcomes were analyzed. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) and odds ratios (ORs) were estimated as indicators of the degree of correlation. This research was registered on PROSPERO (International prospective register of systematic reviews), ID: CRD42022315070.

Results

In total, 57 articles and 14184 cases were included in this study. High EpCAM expression had a significant coherence with a poorer overall survival (OS) (HR: 1.30, 95% CI: 1.08-1.58, P < 0.01) and a worse disease-free survival (DFS) (HR: 1.58, 95% CI: 1.28-1.95, P < 0.01), especially of gastrointestinal tumors' OS (HR: 1.50, 95% CI: 1.15-1.95, P < 0.01), and DFS (HR: 1.84, 95% CI: 1.52-2.33, P < 0.01). The DFS of head and neck tumors (HR: 2.33, 95% CI: 1.51-3.61, P < 0.01) was also associated with the overexpression of EpCAM. There were no positive relationships between the overexpression of EpCAM and sex (RR: 1.03, 95% CI: 0.99-1.07, P = 0.141), T classification (RR: 0.93, 95% CI: 0.82-1.06, P = 0.293), lymph node metastasis (RR: 0.85, 95% CI: 0.54-1.32, P = 0.461), distant metastasis (RR: 0.97, 95% CI: 0.84-1.10, P = 0.606), vascular infiltration (RR: 1.05, 95% CI: 0.85-1.29, P = 0.611), and TNM stage (RR: 0.93, 95% CI: 0.83-1.04, P = 0.187). However, the overexpression of EpCAM exhibited a significant association with the histological grades (RR: 0.88, 95% CI: 0.80-0.97, P < 0.01).

Conclusion

Based on pooled HRs, the positive expression of EpCAM was totally correlated to a worse OS and DFS in solid tumors. The expression of EpCAM was related to a worse OS in gastrointestinal tumors and a worse DFS in gastrointestinal tumors and head and neck tumors. Moreover, EpCAM expression was correlated with the histological grade. The results presented pointed out that EpCAM could serve as a prognostic biomarker for gastrointestinal and head and neck tumors.

Systematic review registration

https://www.crd.york.ac.uk/prospero, identifier CRD42022315070.

Understanding the versatile roles and applications of EpCAM in cancers: from bench to bedside

Epithelial cell adhesion molecule (EpCAM) functions not only in physiological processes but also participates in the development and progression of cancer. In recent decades, extensive efforts have been made to decipher the role of EpCAM in cancers. Great advances have been achieved in elucidating its structure, molecular functions, pathophysiological mechanisms, and clinical applications. Beyond its well-recognized role as a biomarker of cancer stem cells (CSCs) or circulating tumor cells (CTCs), EpCAM exhibits novel and promising value in targeted therapy. At the same time, the roles of EpCAM in cancer progression are found to be highly context-dependent and even contradictory in some cases. The versatile functional modules of EpCAM and its communication with other signaling pathways complicate the study of this molecule. In this review, we start from the structure of EpCAM and focus on communication with other signaling pathways. The impacts on the biology of cancers and the up-to-date clinical applications of EpCAM are also introduced and summarized, aiming to shed light on the translational prospects of EpCAM.

Amphiregulin increases migration and proliferation of epithelial ovarian cancer cells by inducing its own expression via PI3-kinase signaling

The epidermal growth factor receptor (EGFR) is overexpressed in many types of cancer, including epithelial ovarian cancer (EOC), and its expression has been found to correlate with advanced stage and poor prognosis. The EGFR ligand amphiregulin (AREG) has been investigated as a target for human cancer therapy and is known to have an autocrine role in many cancers. A cytokine array identified AREG as one of several cytokines upregulated by EGF in a phosphatidylinositol 3-kinase (PI3-K) dependent manner in EOC cells. To investigate the functional role of AREG in EOC, its effect on cellular migration and proliferation was assessed in two EOC cells lines, OV167 and SKOV3. AREG increased both migration and proliferation of EOC cell line models through activation of PI3-K signaling, but independent of mitogen activated protein kinase (MAPK) signaling. Through an AREG autocrine loop mediated via PI3-K, upregulation of AREG led to increased levels of both AREG transcript and secreted AREG, while downregulation of endogenous AREG decreased the ability of exogenous AREG to induce cell migration and proliferation. Further, inhibition of endogenous AREG activity or metalloproteinase activity decreased EGF-induced EOC migration and proliferation, indicating a role for soluble endogenous AREG in mediating the functional effects of EGFR in inducing migration and proliferation in EOC.

Functional Implications of the Dynamic Regulation of EpCAM during Epithelial-to-Mesenchymal Transition

Epithelial cell adhesion molecule (EpCAM) is a transmembrane glycoprotein expressed in epithelial tissues. EpCAM forms intercellular, homophilic adhesions, modulates epithelial junctional protein complex formation, and promotes epithelial tissue homeostasis. EpCAM is a target of molecular therapies and plays a prominent role in tumor biology. In this review, we focus on the dynamic regulation of EpCAM expression during epithelial-to-mesenchymal transition (EMT) and the functional implications of EpCAM expression on the regulation of EMT. EpCAM is frequently and highly expressed in epithelial cancers, while silenced in mesenchymal cancers. During EMT, EpCAM expression is downregulated by extracellular signal-regulated kinases (ERK) and EMT transcription factors, as well as by regulated intramembrane proteolysis (RIP). The functional impact of EpCAM expression on tumor biology is frequently dependent on the cancer type and predominant oncogenic signaling pathways, suggesting that the role of EpCAM in tumor biology and EMT is multifunctional. Membrane EpCAM is cleaved in cancers and its intracellular domain (EpICD) is transported into the nucleus and binds β-catenin, FHL2, and LEF1. This stimulates gene transcription that promotes growth, cancer stem cell properties, and EMT. EpCAM is also regulated by epidermal growth factor receptor (EGFR) signaling and the EpCAM ectoderm (EpEX) is an EGFR ligand that affects EMT. EpCAM is expressed on circulating tumor and cancer stem cells undergoing EMT and modulates metastases and cancer treatment responses. Future research exploring EpCAM’s role in EMT may reveal additional therapeutic opportunities.

EpCAM cellular functions in adhesion and migration, and potential impact on invasion: A critical review

EpCAM has long been known as a cell surface protein highly expressed in carcinomas. It has since become one of the key cancer biomarkers. Despite its high fame, its actual role in cancer development is still controversial. Beyond a flurry of correlative studies, which point either to a positive or a negative link with tumour progression, there has been surprisingly few studies on the actual cellular mechanisms of EpCAM and on their functional consequences. Clearly, EpCAM plays multiple important roles, in cell proliferation as well as in cell adhesion and migration. The two latter functions, directly relevant for metastasis, are the focus of this review. We attempt here to bring together the available experimental data to build a global coherent view of EpCAM functions. We also include in this overview EpCAM2/Trop2, the close relative of EpCAM. At the core of EpCAM (and EpCAM2/Trop2) function stands the ability to repress contractility of the actomyosin cell cortex. This activity appears to involve direct inhibition by EpCAM of members of the novel PKC family and of a specific downstream PKD-Erk cascade. We will discuss how this activity can result in a variety of adhesive and migratory phenotypes, thus potentially explaining at least part of the apparent inconsistencies between different studies. The picture remains fragmented, and we will highlight some of the conflicting evidence and the many unsolved issues, starting with the controversy around its original description as a cell-cell adhesion molecule.

IL‑6 prevents CXCL8‑induced stimulation of EpCAM expression in ovarian cancer cells

Epithelial cell adhesion molecule (EpCAM), which is expressed in the majority of epithelial tissues, exhibits tumor growth promoting abilities and is overexpressed in human epithelial ovarian cancer. Therefore, EpCAM is considered to be a promising target for specific immune‑based therapies. The present study evaluated the role of IL‑6 and IL‑8 in the expression of EpCAM in the A2780 human ovarian cancer cell line. Furthermore, the cellular localization of the EpCAM protein in A2780 cells was determined and the effect of EpCAM inhibition on the proliferation of the A2780 cells was investigated. An MTT assay demonstrated that blocking EpCAM with anti‑EPCAM antibodies had no effect on cellular metabolic activity (proliferation). Gene expression analysis revealed that IL‑8 increased EpCAM expression, whereas IL‑6 and the combination of IL‑6/IL‑8 had no effect on EpCAM expression. Immunofluorescence analysis confirmed that EpCAM is expressed on A2780 cell membranes. The present results demonstrated that IL‑8 increased EpCAM expression at the mRNA level in ovarian cancer cells and suggested a potential role of IL‑6 as an inhibitor of IL‑8‑stimulated EpCAM expression.

METCAM/MUC18 Decreases the Malignant Propensity of Human Ovarian Carcinoma Cells

METCAM/MUC18 is an integral membrane cell adhesion molecule (CAM) in the Ig-like gene super-family. It can carry out common functions of CAMs which is to perform intercellular interactions and interaction of cell with extracellular matrix in tumor microenvironment, to interact with various signaling pathways and to regulate general behaviors of cells. We and other two groups previously suggested that METCAM/MUC18 probably be utilized as a biomarker for predicting the malignant tendency of clinical ovarian carcinomas, since METAM/MUC18 expression appears to associate with the carcinoma at advanced stages. It has been further postulated to promote the malignant tendency of the carcinoma. However, our recent research results appear to support the conclusion that the above positive correlation is fortuitous; actually METCAM/MUC18 acts as a tumor and metastasis suppressor for the ovarian carcinoma cells. We also suggest possible mechanisms in the METCAM/MUC18-mediated early tumor development and metastasis of ovarian carcinoma. Moreover, we propose to employ recombinant METCAM/MUC18 proteins and other derived products as therapeutic agents to treat the ovarian cancer patients by decreasing the malignant potential of ovarian carcinoma.

The emerging roles and therapeutic potential of exosomes in epithelial ovarian cancer

Ovarian cancer (OC) is one of the three types of malignant tumors in the female reproductive system, and epithelial ovarian cancer (EOC) is its most typical form. Due to the asymptomatic nature of the early stages and resistance to chemotherapy, EOC has both a poor prognosis and a high fatality rate. Current treatments for OC are very limited, and the 5-years survival rate is approximately 30%. Exosomes, which are microvesicles ranging from approximately 30-100 nm in size that are secreted by living cells, can be produced from different cell types and detected in various body fluids. Cancer cells can secrete more exosomes than healthy cells, and more importantly, the content of cancer cell-derived exosomes is distinct. The exosomes shedding from tumor cells are considered to be involved in tumor progression and metastasis. As such, exosomes are expected to be potential tools for tumor diagnosis and treatment. In this review, we briefly present the emerging roles of exosomes in OC and summarize related articles about their roles as diagnostic or prognostic biomarkers and in the treatment and drug resistance of OC.

EpCAM (CD326) is differentially expressed in craniopharyngioma subtypes and Rathke's cleft cysts

The epithelial cell adhesion molecule (EpCAM) is a type I glycoprotein located on the surface of epithelial cells. It is strongly expressed in many neoplasms and already used in the diagnosis and distinction of various tumour subtypes. Comparative studies about EpCAM expression in cystic sellar lesions are lacking. Therefore, we analysed its distribution pattern in adamantinomatous (aCP) and papillary (pCP) craniopharyngiomas (CP) and Rathke’s Cleft Cysts (RCC) using immunohistochemistry and gene expression profiling. Whereas the protein was not detectable in pCP (n = 10), all aCP (n = 64) showed distinct staining patterns. The vast majority of RCC (n = 10) also appeared positive, but these displayed notably lower labeling scores. Additionally, significantly higher mRNA levels were detectable in aCP (n = 19) when compared to pCP (n = 10) (p = 9.985⁻⁸). Furthermore, pediatric aCP cases, in general, exhibited stronger EpCAM staining levels compared to adult ones (p = 0.015). However, we were not able to verify this result on mRNA level. In summary, our findings demonstrate that EpCAM can be used as an additional distinction-marker for cystic lesions of the sellar region. Its unknown function in aCP and the presence of an approved monoclonal bispecific trifunctional antibody for cancer therapy are interesting starting points for further studies.