Medical Genomics Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea; Cardiovascular and Metabolic Disease Center, Inje University, Busan, South Korea.
Medical Genomics Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea; Department of Functional Genomics, University of Science and Technology, Daejeon, South Korea.
Gastroenterology. 2012 Nov;143(5):1341-1351. doi: 10.1053/j.gastro.2012.07.103. Epub 2012 Jul 27.
BACKGROUND & AIMS: The TOR signaling pathway regulator-like (TIPRL) protein, the mammalian ortholog of yeast TIP41, was identified in an expression profiling screen for factors that regulate human liver carcinogenesis. We investigated the role of human TIPRL protein in hepatocellular carcinoma (HCC).
We measured the level of TIPRL in HCC and adjacent nontumor tissues from patients. We used small interfering RNAs and zebrafish to study the function of TIPRL. We used annexin V propidium iodide staining and immunoblot analyses to measure apoptosis and activation of apoptotic signaling pathways. We used confocal microscopy, coimmunoprecipitation, and glutathione-S transferase pull-down analyses to determine interactions among mitogen-activated protein kinase kinase 7 (MKK7 or MAP2K7), TIPRL, and the protein phosphatase type 2A (PP2Ac). We studied the effects of TIPRL in tumor xenografts in mice.
Levels of TIPRL were higher in HCC tissues and cell lines than nontumor tissues and primary hepatocytes. Knockdown of tiprl expression in zebrafish led to large amounts of apoptosis throughout the embryos. Incubation of HCC cells, but not primary human hepatocytes, with small interfering RNA against TIPRL (siTIPRL) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) caused prolonged activation (phosphorylation) of MKK7 and c-Jun N-terminal kinase (JNK) and led to apoptosis, indicated by cleavage of procaspase-8,-3 and of poly-(adenosine diphosphate-ribose) polymerase. TIPRL bound to MKK7 and PP2Ac and promoted the interaction between MKK7 and PP2Ac. In mice, injection of HCC xenograft tumors with siTIPRL and TRAIL led to tumor apoptosis and regression.
TIPRL is highly up-regulated in human HCC samples and cell lines, compared with noncancerous liver tissues. TIPRL prevents prolonged activation of MKK7 and JNK and TRAIL-induced apoptosis by mediating the interaction between MKK7 and PP2Ac.
TOR 信号通路调节因子样（TIPRL）蛋白是酵母 TIP41 的哺乳动物同源物，它在人类肝癌发生中调节因子的表达谱筛选中被鉴定出来。我们研究了人 TIPRL 蛋白在肝细胞癌（HCC）中的作用。
我们测量了 HCC 患者的 HCC 和相邻非肿瘤组织中的 TIPRL 水平。我们使用小干扰 RNA 和斑马鱼来研究 TIPRL 的功能。我们使用 Annexin V 碘化丙啶染色和免疫印迹分析来测量细胞凋亡和凋亡信号通路的激活。我们使用共聚焦显微镜、免疫共沉淀和谷胱甘肽 S 转移酶拉下分析来确定丝裂原活化蛋白激酶激酶 7（MKK7 或 MAP2K7）、TIPRL 和蛋白磷酸酶 2A（PP2Ac）之间的相互作用。我们研究了 TIPRL 在小鼠肿瘤异种移植中的作用。
TIPRL 在 HCC 组织和细胞系中的水平高于非肿瘤组织和原代肝细胞。在斑马鱼中敲低 tiprl 表达导致胚胎中大量凋亡。与对照 siRNA 相比，用针对 TIPRL 的 siRNA（siTIPRL）和肿瘤坏死因子相关凋亡诱导配体（TRAIL）孵育 HCC 细胞，但不是原代人肝细胞，导致 MKK7 和 c-Jun N-末端激酶（JNK）的延长激活（磷酸化），并导致细胞凋亡，表现为 procaspase-8、-3 和多聚（腺苷二磷酸核糖）聚合酶的裂解。TIPRL 与 MKK7 和 PP2Ac 结合，并促进 MKK7 和 PP2Ac 之间的相互作用。在小鼠中，向 HCC 异种移植肿瘤中注射 siTIPRL 和 TRAIL 导致肿瘤凋亡和消退。
与非癌性肝组织相比，TIPRL 在人 HCC 样本和细胞系中高度上调。TIPRL 通过介导 MKK7 和 PP2Ac 之间的相互作用，防止 MKK7 和 JNK 的延长激活和 TRAIL 诱导的凋亡。
