Investigating the role of the Epstein-Barr virus-encoded oncoprotein, latent membrane protein 1, in cell transformation in vitro




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De Montfort University


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Peer reviewed


Approximately 15–20% of all human cancers are associated with viral infections. Latent membrane protein 1 (LMP1) is the major transforming oncoprotein encoded by Epstein-Barr virus (EBV) and is known for its ability to transform B cells, epithelial cells and rodent fibroblasts in vitro. When expressed in Madin-Darby Canine Kidney (MDCK) epithelial cells, LMP1 induces an epithelial-mesenchymal-transition (EMT), assuming a mesenchymal phenotype. The tumour microenvironment (TME) has emerged as an important target for cancer therapy, and carcinoma-associated fibroblasts (CAFs) are known to play a vital role in the TME: research suggests that both fibroblasts and epithelial cells (via EMT), may be potential sources of CAFs. This study investigates the role of LMP1-mediated secretions on epithelial cell and fibroblast transformation, migration, invasion and recruitment. Findings presented herein demonstrate that conditioned medium taken from LMP1-expressing cells induces EMT in epithelial cells and activates fibroblast-to-myofibroblast differentiation in human dermal fibroblasts, as evidenced by classic cadherin switching, and an increase in the mesenchymal markers, vimentin, vinculin, αSMA and fibronectin. Furthermore, conditioned medium from LMP1-expressing cells enhances cell motility and invasion in both epithelial cells and fibroblasts – an effect that is abrogated by inhibition of both TGFβ and ERK/MAPK signalling in fibroblasts. Moreover, results presented herein demonstrate that fibroblast recruitment is enhanced by LMP1-conditioned medium. Since a growing body of evidence suggests that 3D cell culture systems mimic the in vivo TME more accurately than traditional 2D cultures the final aim of this study was to develop an in vitro 3D cellular model of adult human dermal fibroblasts (HDFa) which can be used as a model to study the role of soluble factors secreted by LMP1-expressing cells in transforming stromal cells found in the TME to facilitate tumour progression. LMP1-conditioned medium was also shown to enhance fibroblast motility, invasion and recruitment in this 3D cell model that more accurately mimics the cells’ natural in vivo environment. The development of this 3D cellular model provides an opportunity for further novel research into the relationship between LMP1-conditioned medium and stromal cell behaviour. Taken together, these findings suggest a role for LMP1-mediated secretions in cell transformation, enhanced cell motility, invasion and recruitment, not only contributing to the highly metastatic nature of tumours, but also recruiting fibroblasts to the TME.





Research Institute