Epstein–Barr virus-encoded LMP1 induces a hyperproliferative and inflammatory gene expression programme in cultured keratinocytes

Abstract

SCC12F cells are a line of keratinocytes that retain the capacity for terminal differentiation in vitro. We showed previously that the Epstein-Barr virus (EBV)-encoded oncogene latent membrane protein 1 (LMP1) altered SCC12F morphology in vitro, downregulated cell-cell-adhesion molecule expression and promoted cell motility. In organotypic raft culture, LMP1-expressing cells failed to stratify and formed poorly organized structures which displayed impaired terminal differentiation. To understand better the mechanism(s) by which LMP1 induces these effects, we generated SCC12F cells in which LMP1 expression is inducible. Following induction, these cells exhibited phenotypic changes similar to those observed previously and allowed us to investigate the effects of LMP1 expression on cellular pathways associated with growth, differentiation and morphology. Using microarrays and a number of confirmatory techniques, we identified sets of differentially expressed genes that are characteristically expressed in inflammatory and hyperproliferative epidermis, including chemokines, cytokines and their receptors, growth factors involved in promoting epithelial cell motility and proliferation and signalling molecules that regulate actin filament reorganization and cell movement. Among the genes whose expression was differentially induced significantly by LMP1, the induction of IL-1b and IL-1a was of particular interest, as many of the LMP1-regulated genes identified are established targets of these cytokines. Our findings suggest that alterations in the IL-1 signalling network may be responsible for many of the changes in host-cell gene expression induced in response to LMP1. Identification of these LMP1-regulated genes helps to define the mechanism(s) by which this oncoprotein influences cellular pathways that regulate terminal differentiation, cell motility and inflammation.

Canonical NF-κB Activation Is Essential for Epstein-Barr Virus Latent Membrane Protein 1 TES2/CTAR2 Gene Regulation

“…Identification of the gene(s) responsible for these effects would be of considerable interest. Surprisingly, the abundance of most cell RNAs did not change substantially after 9 h. These results contrast with a prior study, in which LMP1 induction of IL-1␣ and IL-1␤ was suggested to secondarily account for most LMP1 effects on epithelial cell RNA regulation (45). Indeed, LMP1 TES2-inducible expression activates NF-B more robustly than culture of the cells with high concentrations of IL-1␤ (unpublished data).…”

Augmented Latent Membrane Protein 1 Expression from Epstein-Barr Virus Episomes with Minimal Terminal Repeats

“…Cellular phenotypic changes observed in this study are consistent with those previously described as accompanying increased levels of LMP1 expression (18,32,36,43). In shortterm proliferation assays, the 8TR CCL20.2/B95-8 clone expressing intermediate levels of LMP1 grew fastest, whereas the 12TR clone with the least and 6TR clone with the greatest LMP1 grew slower, if at all.…”

“…Growth and morphological alterations in TR-defined clonal populations. Forced expression of LMP1 in transfection assays has been reported to produce striking alterations in epithelial cell morphology, characterized by a loss of the original cuboidal appearance and the development of a more fusiform morphology (18,32,36,43). Surprisingly, when expressed here in the physiologically relevant context of virus infection, LMP1 conferred on the three clones of the CCL20.2 carcinoma cell line a graduated change in phenotype that paralleled stepwise increases in LMP1 expression levels (Fig.…”

Epstein-Barr Virus Zta-Induced Immunomodulators from Nasopharyngeal Carcinoma Cells Upregulate Interleukin-10 Production from Monocytes

“…EBV LMP1 is a potential candidate because its expression is upregulated during lytic infection and it can induce COX-2 and PGE 2 in NPC cells (9,48). A recent study using microarray analysis shows that LMP1 also augments transcription of GM-CSF in keratinocytes (46). In addition, multiple roles of LMP1 in immune evasion have been reported (45).…”