Svastová Eliska, Zilka Norbert, Zat'ovicová Miriam, Gibadulinová Adriana, Ciampor Fedor, Pastorek Jaromír, Pastoreková Silvia
Centre of Molecular Medicine, Institute of Virology, Slovak Academy of Sciences, Dúbravská cesta 9, 845 05 Bratislava, Slovak Republic.
Exp Cell Res. 2003 Nov 1;290(2):332-45. doi: 10.1016/s0014-4827(03)00351-3.
Carbonic anhydrase IX (CA IX) is a cancer-associated transmembrane isoform of zinc metalloenzymes that catalyse interconversion between carbon dioxide and bicarbonate. CA IX is strongly induced by tumor hypoxia and has been proposed to participate in acidification of tumor microenvironment and in cell adhesion. To elucidate the cell adhesion-related role of CA IX, we investigated its subcellular localization and relationship to E-cadherin, a key adhesion molecule whose loss or destabilization is linked to tumor invasion. For this purpose, we generated MDCK cells with constitutive expression of human CA IX protein. During the monolayer formation, CA IX was localized to cell-cell contacts and its distribution in lateral membranes overlapped with E-cadherin. Calcium switch-triggered disruption and reconstitution of cell contacts resulted in relocalization of both CA IX and E-cadherin to cytoplasm and back to plasma membrane. A similar phenomenon was observed in hypoxia-treated and reoxygenated cells. Moreover, CA IX-expressing MDCK cells exhibited reduced cell adhesion capacity and lower levels of Triton-insoluble E-cadherin. Finally, CA IX was found to coprecipitate with beta-catenin. We conclude that CA IX has a capacity to modulate E-cadherin-mediated cell adhesion via interaction with beta-catenin, which could be of potential significance in hypoxia-induced tumor progression.
碳酸酐酶IX（CA IX）是一种与癌症相关的锌金属酶跨膜异构体，可催化二氧化碳和碳酸氢盐之间的相互转化。CA IX在肿瘤缺氧时被强烈诱导，有人提出它参与肿瘤微环境的酸化和细胞黏附。为了阐明CA IX在细胞黏附方面的作用，我们研究了其亚细胞定位以及与E-钙黏蛋白的关系，E-钙黏蛋白是一种关键的黏附分子，其缺失或不稳定与肿瘤侵袭有关。为此，我们构建了组成型表达人CA IX蛋白的MDCK细胞。在单层形成过程中，CA IX定位于细胞间接触部位，其在侧膜中的分布与E-钙黏蛋白重叠。钙开关触发的细胞接触破坏和重建导致CA IX和E-钙黏蛋白重新定位到细胞质中，然后又回到质膜。在缺氧处理和复氧的细胞中也观察到了类似现象。此外，表达CA IX的MDCK细胞表现出细胞黏附能力降低以及Triton不溶性E-钙黏蛋白水平降低。最后，发现CA IX与β-连环蛋白共沉淀。我们得出结论，CA IX能够通过与β-连环蛋白相互作用来调节E-钙黏蛋白介导的细胞黏附，这在缺氧诱导的肿瘤进展中可能具有潜在意义。
