Loss of the EPH receptor B6 contributes to colorectal cancer metastasis

Silvia Mateo-Lozano,Fernando Cartón-García,Paulo Rodrigues,Yaiza Nuñez,Priscila Guimarães De Marcondes,Santiago Ramón Y Cajal,Yolanda Fernández,Rocco Mazzolini,Toshimitsu Matsui,Stefania Landolfi,Javier Hernández‐Losa ,Elena Andretta,Irati Macaya,Ibane Abasolo,Higinio Dopeso,Elsa Da Palma Afonso ,John M Mariadason,Sarah Bazzocco,Lizbeth M Jiménez-Flores ,Karina Cacci,Edgar Del Llano,Rocío Nieto ,Simó Schwartz ,Lucia Suárez‐López ,Josipa Bilić ,Diego Arango

doi:10.1038/srep43702

Abstract

Although deregulation of EPHB signaling has been shown to be an important step in colorectal tumorigenesis, the role of EPHB6 in this process has not been investigated. We found here that manipulation of EPHB6 levels in colon cancer cell lines has no effect on their motility and growth on a solid substrate, soft agar or in a xenograft mouse model. We then used an EphB6 knockout mouse model to show that EphB6 inactivation does not efficiently initiate tumorigenesis in the intestinal tract. In addition, when intestinal tumors are initiated genetically or pharmacologically in EphB6+/+ and EphB6−/− mice, no differences were observed in animal survival, tumor multiplicity, size or histology, and proliferation of intestinal epithelial cells or tumor cells. However, reintroduction of EPHB6 into colon cancer cells significantly reduced the number of lung metastasis after tail-vein injection in immunodeficient mice, while EPHB6 knockdown in EPHB6-expressing cells increased their metastatic spread. Consistently, although EPHB6 protein expression in a series of 130 primary colorectal tumors was not associated with patient survival, EPHB6 expression was significantly lower in lymph node metastases compared to primary tumors. Our results indicate that the loss of EPHB6 contributes to the metastatic process of colorectal cancer.

Highlights

Deregulation of EPHB signaling has been shown to be an important step in colorectal tumorigenesis, the role of EPHB6 in this process has not been investigated
Because EPHB signaling through other family members has been previously shown to be important in colorectal tumorigenesis[5,6] we decided to investigate the role of EPHB6 in colorectal carcinogenesis using isogenic in vitro systems
The overexpression of EPHB6 was confirmed by Western blotting and the membrane localization of the ectopically expressed EPHB6 was confirmed by flow cytometry (Fig. 1A–D)

Summary

Introduction

Deregulation of EPHB signaling has been shown to be an important step in colorectal tumorigenesis, the role of EPHB6 in this process has not been investigated. Erythropoietin-Producing Hepatoma (EPH) receptors constitute the largest known family of receptor tyrosine kinases characterized in humans These receptors and their Ephrin ligands are important for recognizing signals from the extracellular environment and are involved in cell-cell interaction, participating in cell adhesion, migration and proliferation. Consistent with these roles, several members of the EPH family have been shown to be involved in tumorigenesis in different organs[1,2,3,4,5,6]. We have investigated the importance of the loss of EPHB6 during intestinal tumorigenesis using isogenic in vitro systems, different mouse models and annotated collections of primary colorectal tumors, and found that the loss of EPHB6 contributes to the metastatic spread of colorectal tumors

Methods

Results

Conclusion