Jeong Geun Ok, Shin Sang Hun, Seo Eun Jin, Kwon Yang Woo, Heo Soon Chul, Kim Ki-Hyung, Yoon Man-Soo, Suh Dong-Soo, Kim Jae Ho
Medical Research Center for Ischemic Tissue Regeneration, School of Medicine, Pusan National University, Yangsan 626-870, Gyeongsangnam-do, Republic of Korea.
Cell Physiol Biochem. 2013;32(2):253-63. doi: 10.1159/000354434. Epub 2013 Jul 31.
Transcriptional co-activator with PDZ-binding motif (TAZ), a downstream effector of the Hippo pathway, has been reported to regulate organ size, tissue homeostasis, and tumorigenesis by acting as a transcriptional co-activator. Lysophosphatidic acid (LPA) is a bioactive lipid implicated in tumorigenesis and metastasis of ovarian cancer through activation of G protein-coupled receptors. However, the involvement of TAZ in LPA-induced tumorigenesis of ovarian cancer has not been elucidated.
In order to demonstrate the role of TAZ in LPA-stimulated tumorigenesis, the effects of LPA on TAZ expression and cell migration were determined by Western blotting and chemotaxis analyses in R182 human epithelial ovarian cancer cells.
Treatment of R182 cells with the LPA receptor inhibitor Ki16425 blocked LPA-induced cell migration. In addition, transfection of R182 cells with small interfering RNA specific for LPA receptor 1 resulted in abrogation of LPA-stimulated cell migration. LPA induced phosphorylation of ERK and p38 MAP kinase in R182 cells and pretreatment of cells with the MEK-ERK pathway inhibitor U0126, but not the p38 MAPK inhibitor SB202190, resulted in abrogation of LPA-induced cell migration. Pretreatment of R182 cells with U0126 attenuated LPA-induced mRNA levels of TAZ and its transcriptional target genes, such as CTGF and CYR61, without affecting phosphorylation level of YAP. These results suggest that MEK-ERK pathway plays a key role in LPA-induced cell migration and mRNA expression of TAZ in R182 cells, without affecting stability of TAZ protein. In addition, small interfering RNA-mediated silencing of TAZ expression attenuated LPA-stimulated migration of R182 cells. These results suggest that TAZ plays a key role in LPA-stimulated migration of epithelial ovarian cancer cells.
含PDZ结合基序的转录共激活因子（TAZ）是Hippo信号通路的下游效应分子，据报道它作为转录共激活因子可调节器官大小、组织稳态和肿瘤发生。溶血磷脂酸（LPA）是一种生物活性脂质，通过激活G蛋白偶联受体参与卵巢癌的肿瘤发生和转移。然而，TAZ在LPA诱导的卵巢癌肿瘤发生中的作用尚未阐明。
为了证明TAZ在LPA刺激的肿瘤发生中的作用，通过蛋白质免疫印迹法和趋化性分析，在R182人上皮性卵巢癌细胞中测定LPA对TAZ表达和细胞迁移的影响。
用LPA受体抑制剂Ki16425处理R182细胞可阻断LPA诱导的细胞迁移。此外，用针对LPA受体1的小干扰RNA转染R182细胞导致LPA刺激的细胞迁移被消除。LPA诱导R182细胞中ERK和p38丝裂原活化蛋白激酶的磷酸化，用MEK-ERK通路抑制剂U0126预处理细胞，但不用p38丝裂原活化蛋白激酶抑制剂SB202190预处理细胞，可导致LPA诱导的细胞迁移被消除。用U0126预处理R182细胞可减弱LPA诱导的TAZ及其转录靶基因（如CTGF和CYR61）的mRNA水平，而不影响YAP的磷酸化水平。这些结果表明，MEK-ERK通路在LPA诱导的R182细胞迁移和TAZ的mRNA表达中起关键作用，而不影响TAZ蛋白的稳定性。此外，小干扰RNA介导的TAZ表达沉默减弱了LPA刺激的R182细胞迁移。这些结果表明，TAZ在LPA刺激的上皮性卵巢癌细胞迁移中起关键作用。
