1. Epstein-Barr virus LMP1 protein promotes proliferation and inhibits differentiation of epithelial cells via activation of YAP and TAZ.
- Author
-
Singh DR, Nelson SE, Pawelski AS, Kansra AS, Fogarty SA, Bristol JA, Ohashi M, Johannsen EC, and Kenney SC
- Subjects
- Humans, Cell Differentiation, Cell Proliferation, Epithelial Cells metabolism, Herpesvirus 4, Human genetics, Viral Matrix Proteins genetics, Viral Matrix Proteins metabolism, YAP-Signaling Proteins, Epstein-Barr Virus Infections, Nasopharyngeal Neoplasms genetics
- Abstract
Latent Epstein-Barr virus (EBV) infection promotes undifferentiated nasopharyngeal carcinomas (NPCs) in humans, but the mechanism(s) for this effect has been difficult to study because EBV cannot transform normal epithelial cells in vitro and the EBV genome is often lost when NPC cells are grown in culture. Here we show that the latent EBV protein, LMP1 (Latent membrane protein 1), induces cellular proliferation and inhibits spontaneous differentiation of telomerase-immortalized normal oral keratinocytes (NOKs) in growth factor-deficient conditions by increasing the activity of the Hippo pathway effectors, YAP (Yes-associated protein) and TAZ (Transcriptional coactivator with PDZ-binding motif). We demonstrate that LMP1 enhances YAP and TAZ activity in NOKs both by decreasing Hippo pathway-mediated serine phosphorylation of YAP and TAZ and increasing Src kinase-mediated Y357 phosphorylation of YAP. Furthermore, knockdown of YAP and TAZ is sufficient to reduce proliferation and promote differentiation in EBV-infected NOKs. We find that YAP and TAZ are also required for LMP1-induced epithelial-to-mesenchymal transition. Importantly, we demonstrate that ibrutinib (an FDA-approved BTK inhibitor that blocks YAP and TAZ activity through an off-target effect) restores spontaneous differentiation and inhibits proliferation of EBV-infected NOKs at clinically relevant doses. These results suggest that LMP1-induced YAP and TAZ activity contributes to the development of NPC.
- Published
- 2023
- Full Text
- View/download PDF