Over-expression of the mitogen-activated protein kinase (MAPK) kinase (MEK)-MAPK in hepatocellular carcinoma: its role in tumor progression and apoptosis.
Over-expression of the mitogen-activated protein kinase (MAPK) kinase (MEK)-MAPK in hepatocellular carcinoma: its role in tumor progression and apoptosis.
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DOI：
10.1186/1471-230x-3-19
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发表时间：
2003-08-08
影响因子：
2.4
通讯作者：
Tran E
中科院分区：
文献类型：
--
作者：
Huynh H;Nguyen TT;Chow KH;Tan PH;Soo KC;Tran E
肝细胞癌（HCC）是东南亚最常见的恶性肿瘤之一。虽然MEK-MAPK的激活通常与细胞生长相关，但MEK-MAPK在肝癌细胞生长和存活中的作用尚未确定。用免疫组化法检测磷酸化MAPK和MEK 1/2的表达。采用MTT法和ELISA法检测细胞活力和细胞增殖。用脱氧核苷酸转移酶介导的dUTP缺口末端标记法（TUNEL）检测凋亡细胞。蛋白质印迹分析进行，以确定参与MEK-MAPK和凋亡途径的蛋白质的水平。通过转染研究MEK-MAPK通路在肝癌细胞生长和存活中的作用。我们报告说，磷酸化的MEK 1/2在Ser 217/221检测的免疫组织化学在100%（46 46）的肝癌检查。阳性信号定位于肝癌细胞核，而不发育不良的肝细胞和间质细胞。MAPK的过度表达和磷酸化也分别在91%（42/46）和69%（32/46）的HCC中检测到。磷酸化MEK 1/2阳性细胞的百分比随着肿瘤分期的进展而增加。在体外，用MEK 1/2特异性抑制剂U 0126和PD 98059处理人HepG 2和Hep 3B细胞导致生长抑制和凋亡。U 0126诱导细胞色素c的释放，并增加caspase-3，caspase-7和聚ADP-核糖聚合酶（PARP）的切割。抑制磷脂酰肌醇3-激酶（PI-3 K）、c-Jun N-末端激酶（JNK）和p38激酶活性仅引起HepG 2和Hep 3B细胞轻度凋亡。活化的MEK 1转染细胞在体外对UO 126诱导的细胞凋亡更具抵抗力，并且在SCID小鼠中形成的肿瘤比模拟转染细胞更大。总之，我们的研究结果表明，MEK-MAPK在肝癌细胞的生长和存活中起着重要的作用，并表明阻断MEK-MAPK活性可能是治疗肝癌的另一种方法。
Hepatocellular carcinoma (HCC) is one of the most common malignancies in South East Asia. Although activation of the MEK-MAPK is often associated with cellular growth, the role of MEK-MAPK in growth and survival of hepatocarcinoma cells has not been established. Immuno-histochemistry was used to localize phosphorylated MAPK and MEK1/2 in the tissues. 3-(4,5-Dimethylthiazol-2-y1)-2,5-diphenyltetrazolium bromide (MTT) assay and ELISA were used to determine cell viability and cell proliferation. Deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay was used to detect apoptotic cells. Western blots analysis was performed to determine the levels of proteins involved in the MEK-MAPK and apoptotic pathways. Transfection study was performed to assess the role of MEK-MAPK pathway in growth and survival of liver cancer cells. We report that phosphorylation of MEK1/2 at Ser217/221 was detected by immuno-histochemistry in 100% (46 of 46) of HCCs examined. A positive signal was localized in the nuclei of hepatocarcinoma cells but not in dysplastic hepatocytes or stromal cells. Over-expression and phosphorylation of MAPK was also detected in 91% (42 of 46) and 69% (32 of 46) of HCCs examined, respectively. The percentage of cells showing positively for phosphorylated MEK1/2 increased with advancing tumor stage. In vitro, treatment of human HepG2 and Hep3B cells with MEK1/2 specific inhibitors U0126 and PD98059 led to growth inhibition and apoptosis. U0126 induced the release of cytochrome c and increased the cleavage of caspase-3, caspase-7, and poly ADP-ribose polymerase (PARP). Inhibition of phosphatidylinositol 3-kinase (PI-3K), c-Jun N-terminal kinase (JNK) and p38 kinase activities caused only a mild apoptosis in HepG2 and Hep3B cells. Activated MEK1-transfected cells were more resistant to UO126-induced apoptosis in vitro and formed larger tumors in SCID mice than mock-transfected cells. In conclusion, our results demonstrate that MEK-MAPK plays an important role in the growth and survival of liver cancer cells and suggest that blocking MEK-MAPK activity may represent an alternative approach for the treatment of liver cancer.