Scholle F, Bendt K M, Raab-Traub N
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295, USA.
J Virol. 2000 Nov;74(22):10681-9. doi: 10.1128/jvi.74.22.10681-10689.2000.
The Epstein-Barr virus LMP2A protein was expressed in a human keratinocyte cell line, HaCaT, and effects on epithelial cell growth were detected in organotypic raft cultures and in vivo in nude mice. Raft cultures derived from LMP2A-expressing cells were hyperproliferative, and epithelial differentiation was inhibited. The LMP2A-expressing HaCaT cells were able to grow anchorage independently and formed colonies in soft agar. HaCaT cells expressing LMP2A were highly tumorigenic and formed aggressive tumors in nude mice. The LMP2A tumors were poorly differentiated and highly proliferative, in contrast to occasional tumors that arose from parental HaCaT cells and vector control cells, which grew slowly and remained highly differentiated. Animals injected with LMP2A-expressing cells developed frequent metastases, which predominantly involved lymphoid organs. Involucrin, a marker of epithelial differentiation, and E-cadherin, involved in the maintenance of intercellular contact, were downregulated in LMP2A tumors. Whereas activation of the mitogen-activated protein kinase pathway was not observed, phosphatidylinositol-3-kinase (PI3-kinase)-dependent activation of the serine-threonine kinase Akt was detected in LMP2A-expressing cells and LMP2A tumors. Inhibition of this pathway blocked growth in soft agar. These data indicate that LMP2A greatly affects cell growth and differentiation pathways in epithelial cells, in part through activation of the PI3-kinase-Akt pathway.
爱泼斯坦-巴尔病毒LMP2A蛋白在人角质形成细胞系HaCaT中表达，并在器官型筏式培养物和裸鼠体内检测其对上皮细胞生长的影响。源自表达LMP2A细胞的筏式培养物增殖过度，上皮分化受到抑制。表达LMP2A的HaCaT细胞能够独立于锚定生长，并在软琼脂中形成集落。表达LMP2A的HaCaT细胞具有高度致瘤性，在裸鼠体内形成侵袭性肿瘤。与偶尔由亲代HaCaT细胞和载体对照细胞产生的生长缓慢且保持高度分化的肿瘤不同，LMP2A肿瘤分化差且增殖性高。注射表达LMP2A细胞的动物频繁发生转移，主要累及淋巴器官。参与上皮分化的标记物兜甲蛋白和参与维持细胞间接触的E-钙黏蛋白在LMP2A肿瘤中下调。虽然未观察到丝裂原活化蛋白激酶途径的激活，但在表达LMP2A的细胞和LMP2A肿瘤中检测到磷脂酰肌醇-3-激酶（PI3-激酶）依赖性的丝氨酸-苏氨酸激酶Akt激活。抑制该途径可阻断软琼脂中的生长。这些数据表明，LMP2A极大地影响上皮细胞中的细胞生长和分化途径，部分是通过激活PI3-激酶-Akt途径实现的。
