Todd Maria C, Petty Heather M, King Jonathan M, Piana Marshall Brytanie N, Sheller Rebecca A, Cuevas Maria E
Biology Department, Southwestern University, Georgetown, TX 78626, USA.
Biology Department, Trinity University, San Antonio, TX 78212, USA.
Oncol Lett. 2015 Jul;10(1):156-162. doi: 10.3892/ol.2015.3160. Epub 2015 Apr 28.
Tumor-specific deregulated expression of claudins, integral membrane proteins found in tight junctions (TJs), has indicated a possible role for TJ disruption in cancer progression. The current study demonstrates the marked overexpression of claudin-3 protein in two breast cancer cell lines of metastatic origin (MCF-7 and MDA-MB-415). Immunofluorescence and differential detergent fractionation analyses revealed that, although claudin-3 was primarily localized at cell junctions, it was also detected intracellularly. Similarly, the siRNA-mediated suppression of claudin-3 did not considerably affect its pattern of subcellular distribution relative to mock-transfected cells. However, there appeared to be a preferential loss of claudin-3 signal in the cytoskeletal fraction. Wound-healing assays were conducted to assess the effect of endogenous overexpression versus siRNA-mediated suppression of claudin-3 on cellular motility in MCF-7 cells. Suppression of claudin-3 protein levels resulted in a marked decrease in the rate of cellular motility relative to mock-transfected cells. These findings suggest that overexpression of claudin-3 may be important in disrupting TJ integrity and thus contribute to enhanced cellular motility, a key component of tumor progression.
紧密连接（TJs）中的整合膜蛋白claudins的肿瘤特异性失调表达表明，TJ破坏在癌症进展中可能发挥作用。当前研究表明，在两种转移性来源的乳腺癌细胞系（MCF-7和MDA-MB-415）中claudin-3蛋白明显过表达。免疫荧光和差异去污剂分级分离分析显示，虽然claudin-3主要定位于细胞连接处，但在细胞内也能检测到。同样，与mock转染细胞相比，siRNA介导的claudin-3抑制对其亚细胞分布模式没有显著影响。然而，细胞骨架部分的claudin-3信号似乎有优先丢失。进行伤口愈合试验以评估内源性过表达与siRNA介导的claudin-3抑制对MCF-7细胞中细胞运动性的影响。与mock转染细胞相比，claudin-3蛋白水平的抑制导致细胞运动速率显著降低。这些发现表明，claudin-3的过表达可能在破坏TJ完整性方面很重要，从而有助于增强细胞运动性，这是肿瘤进展的一个关键组成部分。
