Yun Chawon, Cho Hyeseon, Kim Su-Jeong, Lee Jae-Ho, Park Sun Yi, Chan Gordon K, Cho Hyeseong
Department of Biochemistry and Molecular Biology, Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon, South Korea.
Mol Cancer Res. 2004 Mar;2(3):159-69.
Multinucleated cells have been noted in pathophysiological states of the liver including infection with hepatitis B virus (HBV), the status of which is also closely associated with genomic instability in liver cancer. Here, we showed that hepatitis B virus X oncoprotein (HBx) expression in Chang cells results in a multinuclear phenotype and an abnormal number of centrosomes (n >or=3). Regulation of centrosome duplication in HBx-expressing ChangX-34 cells was defective and uncoupled from the cell cycle. HBx induced amplification of centrosomes, multipolar spindle formation, and chromosomal missegregation during mitosis and subsequently increased the generation of multinucleated cells and micronuclei formation. Treatment with PD98059, a mitogen-activated protein/extracellular signal-regulated kinase (MEK) 1/2 inhibitor, significantly reduced the number of cells with hyperamplified centrosomes and decreased the multinucleated cells and micronuclei formation. Consistently, the phospho-ERK level during cell progression was substantially higher in ChangX-34 cells than that of Chang cells. In contrast, neither wortmannin, an inhibitor of phosphoinositide-3 kinase, nor SB203589, an inhibitor of p38 mitogen-activated protein kinase (MAPK), showed any effects. Introduction of Ras dominant-negative (D/N) and MEK2 D/N genes into ChangX-34 cells significantly alleviated centrosome amplification, whereas introduction of the PKC D/N and PKB D/N genes did not. Thus, our results demonstrate that the HBx induced centrosome hyperamplification and mitotic aberration by activation of the Ras-MEK-MAPK. Intervention of this signaling pathway could suppress the centrosome amplification as well as mitotic aberration. These findings may provide a possible mechanism by which HBx promotes phenotypic progression by predisposing chromosomal alteration in HBV-infected liver.
在肝脏的病理生理状态中已发现多核细胞，包括感染乙型肝炎病毒（HBV），其状态也与肝癌中的基因组不稳定性密切相关。在此，我们表明，在Chang细胞中乙型肝炎病毒X癌蛋白（HBx）的表达导致多核表型和中心体数量异常（n≥3）。在表达HBx的ChangX - 34细胞中，中心体复制的调控存在缺陷，且与细胞周期解偶联。HBx诱导中心体扩增、多极纺锤体形成以及有丝分裂期间的染色体错分，随后增加了多核细胞的产生和微核形成。用丝裂原活化蛋白/细胞外信号调节激酶（MEK）1/2抑制剂PD98059处理，可显著减少中心体过度扩增的细胞数量，并减少多核细胞和微核形成。一致地，在细胞进程中，ChangX - 34细胞中的磷酸化ERK水平显著高于Chang细胞。相比之下，磷脂酰肌醇-3激酶抑制剂渥曼青霉素和p38丝裂原活化蛋白激酶（MAPK）抑制剂SB203589均未显示任何作用。将Ras显性负性（D/N）和MEK2 D/N基因导入ChangX - 34细胞可显著减轻中心体扩增，而导入PKC D/N和PKB D/N基因则无此作用。因此，我们的结果表明，HBx通过激活Ras - MEK - MAPK诱导中心体过度扩增和有丝分裂异常。干预该信号通路可抑制中心体扩增以及有丝分裂异常。这些发现可能提供了一种可能的机制，通过该机制HBx在HBV感染的肝脏中通过易化染色体改变促进表型进展。
