Loss of Phosphatase and Tensin Homolog Enhances Cell Invasion and Migration Through AKT/Sp-1 Transcription Factor/Matrix Metalloproteinase 2 Activation in Hepatocellular Carcinoma and Has Clinicopathologic Significance
Loss of Phosphatase and Tensin Homolog Enhances Cell Invasion and Migration Through AKT/Sp-1 Transcription Factor/Matrix Metalloproteinase 2 Activation in Hepatocellular Carcinoma and Has Clinicopathologic Significance
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DOI：
10.1002/hep.24232
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发表时间：
2011-05-01
期刊：
影响因子：
13.5
通讯作者：
Ng, Irene Oi-Lin
中科院分区：
文献类型：
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作者：
Sze, Karen Man-Fong;Wong, Kris Lai-Ting;Ng, Irene Oi-Lin
磷酸酶和张力蛋白同源物(PTEN)在癌症中经常失活，与癌症晚期或转移有关。然而，PTEN在肝细胞癌转移中的分子机制尚不清楚。在这项研究中，我们发现与相应的非肿瘤肝细胞相比，人肝细胞癌中PTEN蛋白经常(47.5%，=5.40)低表达。显著地，PTEN低表达与较大的肿瘤大小(P=0.021)、肿瘤微卫星形成(P=0.027)和较短的患者总生存期(P=0.035)相关。使用不同的细胞模型，我们观察到PTEN基因敲除的肝癌细胞和PTEN基因敲除的小鼠胚胎成纤维细胞(MEF)具有增强细胞迁移和侵袭能力。除AKT激活外，PTEN基因敲除的肝癌细胞和PTEN-/-MEF中Sp1转录因子(SP1)和基质金属蛋白酶2(MMP2)表达上调，MMP2表达上调。通过双荧光素酶报告基因分析，外源SP1在肝癌细胞中的表达导致MMP2启动子活性增加高达74%，而MMP2启动子上SP1结合位点的缺失导致启动子活性降低高达65%。利用染色质免疫沉淀实验，我们发现在PTEN基因敲除的肝癌细胞中，SP1与MMP2启动子的结合增加。人肝细胞癌中SP1和MMP2的高表达与PTEN的低表达呈显著负相关。结论：PTEN在肝细胞癌中低表达，这种低表达与更具侵袭性的生物学行为和更差的患者生存有关。我们首次提供证据表明，MMP2对PTEN缺失的上调是SP1依赖的。我们的研究结果表明，PTEN通过AKT/SP1/MMP2途径在下调肝癌细胞侵袭中发挥重要作用。(《肝病》2011；53：1558-1569)
Phosphatase and tensin homolog (PTEN) is frequently inactivated in cancers and is associated with advanced stages of cancers or metastasis. However, the molecular mechanism of PTEN in hepatocellular carcinoma (HCC) metastasis is unclear. In this study, we found frequent (47.5%, = 5 40) protein underexpression of PTEN in human HCCs compared with their corresponding nontumorous livers. Significantly, PTEN underexpression was associated with larger tumor size (P = 0.021), tumor microsatellite formation (P = 0.027), and shorter overall survival of patients (P = 0.035). Using different cell models, we observed that PTEN-knockdown HCC cells and PTEN-knockout mouse embryonic fibroblasts (MEFs) had enhanced cell migratory and invasive abilities. In addition to activation of AKT, there was up-regulation of the Sp1 transcription factor (SP1) and matrix metalloproteinase 2 (MMP2), as well as MMP2 activation in PTEN-knockdown HCC cells and PTEN-/- MEFs. With dual luciferase reporter assay, exogenous expression of SP1 in HCC cells led to enhanced MMP2 promoter activity by up to 74%, whereas deletion of the putative SP1 binding site on the MMP2 promoter led to reduced promoter activity by up to 65%. Using chromatin immunoprecipitation assay, we documented increased binding of SP1 to the MMP2 promoter in PTEN-knockdown HCC cells. Overexpression of SP1 and MMP2 was significantly but negatively associated with PTEN underexpression in human HCCs. Conclusion: Our results show that PTEN was underexpressed in HCCs, and this underexpression was associated with more aggressive biological behavior and poorer patient survival. We have provided the first evidence that MMP2 upregulation upon PTEN loss is SP1-dependent. Our findings indicate that PTEN plays a significant role in down-regulating HCC cell invasion via the AKT/SP1/MMP2 pathway. (HEPATOLOGY 2011;53:1558-1569)