Hepatitis B Virus X Protein Confers Resistance of Hepatoma Cells to Anoikis by Up-regulating and Activating p21-Activated Kinase 1
Hepatitis B Virus X Protein Confers Resistance of Hepatoma Cells to Anoikis by Up-regulating and Activating p21-Activated Kinase 1
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乙型肝炎病毒 X 蛋白通过上调和激活 p21 激活激酶 1 赋予肝癌细胞对失巢凋亡的抵抗力
DOI：
10.1053/j.gastro.2012.03.053
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发表时间：
2012-07-01
期刊：
影响因子：
29.4
通讯作者：
Gu, Jianxin
中科院分区：
文献类型：
--
作者：
Xu, Jiejie;Liu, Haiou;Gu, Jianxin
背景与目的：慢性B型肝炎病毒（HBV）感染的患者有发生转移性肝细胞癌（HCC）的风险。转移性癌细胞对失巢凋亡产生抗性。丝氨酸/苏氨酸p21激活激酶（PAK）1调节细胞骨架动力学并保护细胞免受失巢凋亡;它还促进病毒复制。我们研究了PAK 1对人肝癌细胞和小鼠抗失巢凋亡的作用。方法：我们用pHBV1.3（模拟HBV复制）或编码不同HBV蛋白的质粒转染人肝癌细胞;我们进行集落形成和失巢凋亡试验。我们敲低了肝癌细胞中PAK 1和Bcl 2的水平，或抑制了它们的活性，并定量了裸鼠中肿瘤异种移植物的失巢凋亡和生长;我们还测量了从小鼠腹水中分离的肿瘤细胞的失巢凋亡。我们对来自患者的HCC样本中的PAK 1水平进行了免疫组织化学分析。研究结果：表达B病毒X蛋白（HBx）的pHBV1.3转染的人肝癌细胞进行锚定非依赖性增殖，抗失巢凋亡，并具有比未转染细胞更高的Bcl 2水平。HBx的表达增加了Bcl 2和PAK 1的线粒体水平，它们在物理上相互作用。Huh 7和SK-Hep 1细胞的失巢凋亡抗性需要PAK 1活性和Bcl 2。HBx的表达促进了小鼠Huh 7异种移植肿瘤的生长; PAK 1敲低降低了小鼠这些肿瘤的生长和从这些肿瘤分离的细胞的失巢凋亡。在人类HCC样本中，PAK 1水平升高与预后不良、HBV感染和门静脉肿瘤血栓形成相关。结论：HBV蛋白HBx上调PAK 1，使肝癌细胞对失巢凋亡产生抗性，并促进小鼠中侵袭性异种移植肿瘤的生长。在慢性HBV感染患者中，HBx诱导PAK 1可能促进HCC的进展。
BACKGROUND & AIMS: Patients with chronic hepatitis B virus (HBV) infection are at risk for metastatic hepatocellular carcinoma (HCC). Metastatic cancer cells develop resistance to anoikis. The serine/threonine p21-activated kinase (PAK) 1 regulates cytoskeletal dynamics and protects cells from anoikis; it also promotes virus replication. We investigated the effects of PAK1 on anoikis resistance in human hepatoma cells and in mice. METHODS: We transfected human hepatoma cells with pHBV1.3 (to mimic HBV replication) or plasmids encoding different HBV proteins; we performed colony formation and anoikis assays. We knocked down levels of PAK1 and Bcl2, or inhibited their activity, in hepatoma cells and quantified anoikis and growth of tumor xenografts in nude mice; we also measured anoikis of tumor cells isolated from ascites of the mice. We performed immunohistochemical analysis of PAK1 levels in HCC samples from patients. RESULTS: Human hepatoma cells transfected with pHBV1.3 expressing hepatitis B virus X protein (HBx) underwent anchorage-independent proliferation, were resistant to anoikis, and had higher levels of Bcl2 than nontransfected cells. Expression of HBx increased mitochondrial levels of Bcl2 and PAK1, which interacted physically. Anoikis resistance of Huh7 and SK-Hep1 cells required PAK1 activity and Bcl2. Expression of HBx promoted growth of Huh7 xenograft tumors in mice; PAK1 knockdown reduced growth of these tumors in mice and anoikis of cells isolated from these tumors. In human HCC samples, increased levels of PAK1 correlated with poor prognosis, HBV infection, and portal vein tumor thrombosis. CONCLUSIONS: The HBV protein HBx up-regulates PAK1, allows hepatoma cells to become resistant to anoikis, and promotes growth of aggressive xenograft tumors in mice. HBx induction of PAK1 might promote progression of HCC in patients with chronic HBV infection.