Hasegawa Masakazu, Furuya Mitsuko, Kasuya Yoshitoshi, Nishiyama Mariko, Sugiura Tsuyoshi, Nikaido Takashi, Momota Yutaka, Ichinose Masaharu, Kimura Sadao
Department of Molecular Pathology, Chiba University Graduate School of Medicine, Inohana, Chiba, Japan.
Lab Invest. 2007 Sep;87(9):882-92. doi: 10.1038/labinvest.3700657. Epub 2007 Jul 16.
A member of tetraspanin CD151 is a scaffold protein of laminin-binding integrins and it plays an important role in stable interaction between cells and basement membrane. Although the upregulation of CD151 in tumor cells is thought to accelerate tumor invasion and metastasis, detailed pathological investigation on CD151 and its association with integrins has not been well documented, yet. In the present study, we showed that the expression levels of CD151 and its associated integrin subunits in epidermal carcinoma cell HSC5 were higher than those in immortalized epidermal cell HaCaT. By the stimulation of epidermal growth factor, CD151 was dissociated from cell surface and dispersed in the cytoplasm, and alpha3beta1 integrin was concomitantly internalized. To understand the significance of CD151 in tumor cell dynamics, CD151 in HSC5 was knocked down (HSC5(CD151-)), and the expression of integrin subunits and matrix metalloproteinases (MMPs) were investigated. In HSC5(CD151-), striking morphological alteration on Matrigel and laminin, and cytoskeletal rearrangements were demonstrated. alpha3beta1 integrin was internalized in part, and alpha6beta4 integrin was re-distributed from basal site to cell periphery. Quantitative RT-PCR, Western blot and zymography revealed that the expression levels of MMP2, MMP7 and MMP9 were markedly downregulated in HSC5(CD151-). Immunoprecipitation assay demonstrated that MMP7 was co-immunoprecipitated with CD151. In double stainings, MMP7 was colocalized with CD151 at the leading edge of lamellipodia under migratory status. These results elucidated the importance of CD151 as one of the key molecules for integrin-dependent carcinoma-stroma interaction. It is indicated that CD151 might contribute not only to cell stabilization by associating with adhesion complexes but also to cell migration by inducing integrins re-localization and MMPs production.
四跨膜蛋白CD151是层粘连蛋白结合整合素的支架蛋白，在细胞与基底膜的稳定相互作用中发挥重要作用。尽管肿瘤细胞中CD151的上调被认为会加速肿瘤侵袭和转移，但关于CD151及其与整合素关联的详细病理学研究尚未充分记录。在本研究中，我们发现表皮癌细胞HSC5中CD151及其相关整合素亚基的表达水平高于永生化表皮细胞HaCaT。通过表皮生长因子刺激，CD151从细胞表面解离并分散在细胞质中，同时α3β1整合素被内化。为了解CD151在肿瘤细胞动态中的意义，敲低了HSC5中的CD151（HSC5(CD151-)），并研究了整合素亚基和基质金属蛋白酶（MMPs）的表达。在HSC5(CD151-)中，观察到在基质胶和层粘连蛋白上有明显的形态改变以及细胞骨架重排。α3β1整合素部分内化，α6β4整合素从基底部位重新分布到细胞周边。定量RT-PCR、蛋白质印迹和酶谱分析显示，HSC5(CD151-)中MMP2、MMP7和MMP9的表达水平明显下调。免疫沉淀分析表明MMP7与CD151共免疫沉淀。在双重染色中，迁移状态下MMP7与CD151在片状伪足前沿共定位。这些结果阐明了CD151作为整合素依赖性癌-基质相互作用关键分子之一的重要性。表明CD151不仅可能通过与黏附复合物结合促进细胞稳定，还可能通过诱导整合素重新定位和MMPs产生促进细胞迁移。
