Latent membrane protein-1 of Epstein-Barr virus induces the expression
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Biochemical and Biophysical Research Communications 377 (2008) 579–583
0006-291X/$ - see front matter © 2008 Elsevier Inc. All rights reserved
doi:10.1016/j.bbrc.2008.10.007Contents lists available at ScienceDirectBiochemical and Biophysical Research Communicationsjournal homepage: www.elsevier.com/locate/ybbrc
More than 90% of adults world wide are infected with Epstein-Barr virus (EBV), a mem ber of the her pes vi rus fam ily [1]. Like other gamma-her pes viruses, EBV infec tion usu ally results in a latent (non-pro duc tive) state [2]. Recent stud ies have indi cated an asso ci a tion between EBV and var i ous human can cers, includ ing Bur kitt’s lym phoma [3], naso pha ryn geal car ci noma [4], Hodg kin’s lym phoma [5], and lym pho pro lif er a tive dis ease [6]. EBV-asso ci-ated malig nan cies are cat e go rized into three types, based on the expres sion pattern of latent genes: latency (Lat) I, II, and III. Latent mem brane pro tein-1 (LMP1) is expressed in cells with Lat II- and III-type EBV infec tions, and is known to induce the immor tal i za-tion of rest ing B lym pho cytes [7]. LMP1 accel er ates gene expres-sion by acti vat ing var i ous sig nal ing path ways, such as the nuclear fac tor p38/mito gen-acti vated pro tein kinase (p38/MAPK), nuclear fac tor (NF)-jB, c-Jun N-ter mi nal kinase (JNK)/acti va tion pro tein (AP)-1, and phos pha ti dyl in o si tol 3 kinase (PI3K) path ways [8].Small non-cod ing RNA mol e cules, referred to as mi croR NAs (miR NAs), play key roles in diverse bio log i cal pro cesses, includ ing devel op ment, cell pro lif er a tion, dif fer en ti a tion, and apop to sis [9]. They bind to com ple men tary sites in the 39-untrans lated region of their mRNA tar gets and reg u late gene expres sion, either by repress ing trans la tion or induc ing the deg ra da tion of their tar get mRNAs [10]. miR-155 and its pre cur sor, B-cell inte gra tion clus ter (BIC), which are expressed in acti vated cells of the immune sys-tem [11,12], have been shown to be over-expressed in Hodg kin’s lym phoma, primary medi as ti nal dif fuse large B-cell lym pho mas, Bur kitt’s lym phoma [13,14], chronic lym pho cytic leu ke mia, breast can cer, and lung can cer [15]. Although the pre cise mech a nism is unclear, miR-155 is believed to func tion as an onco gene [15]. Cells with a Lat III-type EBV infec tion express higher lev els of BIC and miR-155 than Lat I-type cells [16,17]. To date, the reg u la tory mech-a nism of BIC expres sion in Lat III EBV infec tion is unknown.Mate ri als and meth odsCell lines. The human Bur kitt’s lym phoma cell lines BJAB, Ak at a(+), Ak at a(¡), Ra mos, and Ra mos/AW, and the lym pho blas-toid cell line (LCL) IB4 were cul tured in RPMI 1640 medium (Sigma, St. Louis, MO) sup ple mented with 10% fetal bovine serum (FBS). BJAB was obtained from the Jap a nese Col lec tion of Research Bio re-sources (Tokyo, Japan). Ra mos and Ra mos/AW were obtained from the Euro pean Col lec tion of Ani mal Cell Cul ture (ECACC). Ak at a con tain ing EBV (Ak at a[+]) and Ak at a lack ing EBV (Ak at a[¡]) were pro vided by Dr. K. Tak ada (Hok ka i do Uni ver sity, Japan), while IB4 was obtained from Dr. E. Kie ff (Brig ham and Women’s Hos pi tal, Bos ton, MA, USA).Infec tion of periph e ral blood mono nu clear cells (PBMCs) with EBV. PBMCs were obtained from human periph e ral blood pro vided by healthy vol un teers using lym pho cyte sep a ra tion medium (LSM, Cap-pel, Aurora, OH) with a num ber of mod i fi ca tions. Briefly, a solu t
ion Latent membrane protein-1 of Epstein-Barr virus induces the expression of B-cell integration cluster, a precursor form of microRNA-155, in B lymphoma cell lines qNur Rahadiani a, Tetsuya Takakuwa b, Kristianti Tresnasari a, Eiichi Morii a,*, Katsuyuki Aozasa aa Depart ment of Pathol ogy, Osaka Uni ver sity Grad u ate School of Med i cine, 2-2Yam adoka, Sui ta, Osaka 565-0871, Japanb Depart ment of Human Health Sci ence, Kyoto Uni ver sity Grad u ate School of Med i cine, 53 Shogoin Kawahara-cho, Kyoto 606-8507, Japanarticle infoabstractArticle history:Received 3 October 2008Available online 14 October 2008 miR-155, a micr oR NA, and its pre cur sor form, B-cell inte gra tion clus ter (BIC), are involved in tumor growth. Epstein-Barr virus (EBV)-asso ci ated malig nan cies are cat e go rized into three types, based on their latent gene expres sion pattern: latency I, II, and III. In the pres ent study, we found that infec tion with EBV increased the expres sion of BIC; in addi tion, substantial expres sion of BIC/miR-155 was detected in latency III-, but not in latency I-type cells. In com par i son, latent mem brane pro tein-1 (LMP1) was expressed in latency III-type cells. When LMP1 was over-expressed, BIC expres sion increased, indi cat ing LMP1 medi ates BIC expres sion. LMP1 is a mem brane-asso ci ated pro tein known to acti vate sig nal ing path ways. With the use of path way inhib i-tors, we found that LMP1-induced strong BIC expres sion, pri mar ily through NF-jB and p38/MAPK path ways. These results sug gest that BIC/miR-155 play a role in lym pho ma gen e sis through NF-jB and p38/MAPK path-ways in response to acti va tion by EBV LMP1.© 2008 Elsevier Inc. All rights reserved.Key words: EB virusLym phomaBIC/miR-155LMP1
