Hong In-Kee, Jin Young-June, Byun Hee-Jung, Jeoung Doo-Il, Kim Young-Myeong, Lee Hansoo
Vascular System Research Center and Division of Life Sciences, College of Natural Sciences, and Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chunchon, Kangwon-do 200-701, Korea.
J Biol Chem. 2006 Aug 25;281(34):24279-92. doi: 10.1074/jbc.M601209200. Epub 2006 Jun 23.
The tetraspanin membrane protein CD151 has been suggested to regulate cancer invasion and metastasis by initiating signaling events. The CD151-mediated signaling pathways involved in this regulation remain to be revealed. In this study, we found that stable transfection of CD151 into MelJuSo human melanoma cells lacking CD151 expression significantly increased cell motility, matrix metalloproteinase-9 (MMP-9) expression, and invasiveness. The enhancement of cell motility and MMP-9 expression by CD151 overexpression was abrogated by inhibitors and small interfering RNAs targeted to focal adhesion kinase (FAK), Src, p38 MAPK, and JNK, suggesting an essential role of these signaling components in CD151 signaling pathways. Also, CD151-induced MMP-9 expression was shown to be mediated by c-Jun binding to AP-1 sites in the MMP-9 gene promoter, indicating AP-1 activation by CD151 signaling pathways. Meanwhile, CD151 was found to be associated with alpha(3)beta(1) and alpha(6)beta(1) integrins in MelJuSo cells, and activation of associated integrins was a prerequisite for CD151-stimulated MMP-9 expression and activation of FAK, Src, p38 MAPK, JNK, and c-Jun. Furthermore, CD151 on one cell was shown to bind to neighboring cells expressing CD151, suggesting that CD151 is a homophilic interacting protein. The homophilic interactions of CD151 increased motility and MMP-9 expression of CD151-transfected MelJuSo cells, along with FAK-, Src-, p38 MAPK-, and JNK-mediated activation of c-Jun in an adhesion-dependent manner. Furthermore, C8161 melanoma cells with endogenous CD151 were also shown to respond to homophilic CD151 interactions for the induction of adhesion-dependent activation of FAK, Src, and c-Jun. These results suggest that homophilic interactions of CD151 stimulate integrin-dependent signaling to c-Jun through FAK-Src-MAPKs pathways in human melanoma cells, leading to enhanced cell motility and MMP-9 expression.
四跨膜蛋白CD151被认为可通过启动信号事件来调节癌症侵袭和转移。参与这种调节的CD151介导的信号通路仍有待揭示。在本研究中，我们发现将CD151稳定转染到缺乏CD151表达的MelJuSo人黑色素瘤细胞中，可显著提高细胞运动性、基质金属蛋白酶-9（MMP-9）表达及侵袭性。针对粘着斑激酶（FAK）、Src、p38丝裂原活化蛋白激酶（MAPK）和应激活化蛋白激酶（JNK）的抑制剂和小干扰RNA消除了CD151过表达对细胞运动性和MMP-9表达的增强作用，表明这些信号成分在CD151信号通路中起重要作用。此外，CD151诱导的MMP-9表达被证明是由c-Jun结合到MMP-9基因启动子中的AP-1位点介导的，这表明CD151信号通路可激活AP-1。同时，在MelJuSo细胞中发现CD151与α(3)β(1)和α(6)β(1)整合素相关，相关整合素的激活是CD151刺激MMP-9表达以及FAK、Src、p38 MAPK、JNK和c-Jun激活的前提条件。此外，一个细胞上的CD151被证明可与表达CD151的相邻细胞结合，这表明CD151是一种同源相互作用蛋白。CD151的同源相互作用增加了转染CD151的MelJuSo细胞的运动性和MMP-9表达，同时以粘着依赖性方式通过FAK、Src、p38 MAPK和JNK介导c-Jun的激活。此外，内源性表达CD151的C8161黑色素瘤细胞也被证明对同源CD151相互作用有反应，从而诱导FAK、Src和c-Jun的粘着依赖性激活。这些结果表明，CD151的同源相互作用通过FAK-Src-丝裂原活化蛋白激酶（MAPK）通路刺激人黑色素瘤细胞中整合素依赖性向c-Jun的信号传导，导致细胞运动性增强和MMP-9表达增加。
