The epithelial-mesenchymal transition (EMT) is an essential step in cancer progression. Epithelial cells possess several types of cell-cell junctions, and tight junctions are known to play important roles in maintaining the epithelial program. EMT is characterized by a loss of epithelial markers, including E-cadherin and tight junction proteins. Somewhat surprisingly, the evidence is accumulating that upregulated expression of tight junction proteins plays an important role in the EMT of cancer cells. Tight junctions have distinct tissue-specific and cancer-specific regulatory mechanisms, enabling them to play different roles in EMT. Tight junctions and related signaling pathways are attractive targets for cancer treatments; signal transduction inhibitors and monoclonal antibodies for tight junction proteins may be used to suppress EMT, invasion, and metastasis. Here we review the role of bicellular and tricellular tight junction proteins during EMT. Further investigation of regulatory mechanisms of tight junctions during EMT in cancer cells will inform the development of biomarkers for predicting prognosis as well as novel therapies.

上皮-间质转化（EMT）是癌症进展中必不可少的步骤。上皮细胞具有几种类型的细胞-细胞连接，紧密连接在维持上皮程序中起着重要作用。EMT的特征是上皮标记物（包括E-钙粘蛋白和紧密连接蛋白）缺失。令人惊讶的是，越来越多的证据表明紧密连接蛋白的表达上调在癌细胞的EMT中起着重要作用。紧密连接具有独特的组织特异性和癌症特异性调节机制，使它们在EMT中发挥不同的作用。紧密连接和相关的信号传导途径是癌症治疗的诱人靶点。紧密连接蛋白的信号转导抑制剂和单克隆抗体可用于抑制EMT，侵袭，和转移。在这里，我们回顾了EMT期间双细胞和三细胞紧密连接蛋白的作用。癌细胞EMT期间紧密连接的调节机制的进一步研究将为预测预后以及新疗法的生物标志物的开发提供信息。