Upregulation of LMP1 expression by histone deacetylase inhibitors in an EBV carrying NPC cell line.
OBJECTIVE
In about 60% of Epstein-Barr virus (EBV) carrying nasopharyngeal carcinomas (NPC) LMP1 expressing cells can be detected. The frequency of LMP1 positive cells and the expression level varies from cell to cell in the different tumors. Cell lines derived from EBV positive NPCs loose the virus during in vitro culture. The in vitro infected NPC cell line TWO3-EBV used in our study carries the neomycin-resistance gene containing EBV and expresses low level of LMP1. With this cell line it was thus possible to study the regulation of LMP1 expression by modification of chromatin acetylation state.


METHODS
The TWO-EBV cell line was treated with n -butyrate (NB) or trichostatin A (TSA).


RESULTS
Shown by immunoblotting, the LMP1 level was elevated in the treated samples. Already 2 h after TSA exposure LMP1 expression was higher and it increased up to 24 h. Immunofluorescence staining showed that nearly all cells were LMP1 positive. Neither EBNA2 nor BZLF1 were induced. Tested first 2 h after the treatment, acetylated histone H3 and H4 were already detectable, and their level increased up to 8 h. Chromatin immunoprecipitation (ChIP) verified that the LMP1-promoter (LMP1p) (ED-L1) was acetylated after TSA treatment.


CONCLUSIONS
EBV carrying epithelial cells do not express EBNA-2. We showed that LMP1 expression was upregulated by histone deacetylase inhibitors in an in vitro infected, EBV carrier NPC cell line.
Nishikawa
Jun
J
Microbiology and Tumor Biology Center, Karolinska Institute, S-171 77 Stockholm, Sweden.
Kis
Lorand L
LL
Liu
Anquan
A
Zhang
Xiangning
X
Takahara
Miki
M
Bandobashi
Kentaro
K
Kiss
Csaba
C
Nagy
Noemi
N
Okita
Kiwamu
K
Klein
George
G
Klein
Eva
E
D000107:Acetylation; D002087:Butyrates / Q000494:pharmacology; D002277:Carcinoma / Q000821:virology; D004247:DNA / Q000378:metabolism; D015967:Gene Expression Regulation, Viral; D004854:Herpesvirus 4, Human / Q000235:genetics* / Q000378:metabolism; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D009303:Nasopharyngeal Neoplasms / Q000821:virology; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D015854:Up-Regulation; D014763:Viral Matrix Proteins / Q000235:genetics* / Q000378:metabolism
D002087:Butyrates; C037662:EBV-associated membrane antigen, Epstein-Barr virus; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D012333:RNA, Messenger; D014763:Viral Matrix Proteins; C012589:trichostatin A; D004247:DNA