Bigelow Kristina, Nguyen Thu A
Department of Diagnostic Medicine/Pathobiology, Kansas State University, 1800 Denison Ave,, Manhattan, KS 66506, USA.
BMC Cancer. 2014 Jul 9;14:502. doi: 10.1186/1471-2407-14-502.
Colorectal cancer is one of the most common cancers in the United States with an early detection rate of only 39%. Colorectal cancer cells along with other cancer cells exhibit many deficiencies in cell-to-cell communication, particularly gap junctional intercellular communication (GJIC). GJIC has been reported to diminish as cancer cells progress. Gap junctions are intercellular channels composed of connexin proteins, which mediate the direct passage of small molecules from one cell to the next. They are involved in the regulation of the cell cycle, cell differentiation, and cell signaling. Since the regulation of gap junctions is lost in colorectal cancer cells, the goal of this study is to determine the effect of GJIC restoration in colorectal cancer cells.
Gap Junction Activity Assay and protein analysis were performed to evaluate the effects of overexpression of connexin 43 (Cx43) and treatment of PQ1, a small molecule, on GJIC.
Overexpression of Cx43 in SW480 colorectal cancer cells causes a 6-fold increase of gap junction activity compared to control. This suggests that overexpressing Cx43 can restore GJIC. Furthermore, small molecule like PQ1 directly targeting gap junction channel was used to increase GJIC. Gap junction enhancers, PQ1, at 200 nM showed a 4-fold increase of gap junction activity in SW480 cells. A shift from the P0 to the P2 isoform of Cx43 was seen after 1 hour treatment with 200 nM PQ1.
Overexpression of Cx43 and treatment of PQ1 can directly increase gap junction activity. The findings provide an important implication in which restoration of gap junction activity can be targeted for drug development.
结直肠癌是美国最常见的癌症之一，早期检测率仅为39%。结直肠癌细胞与其他癌细胞一样，在细胞间通讯方面存在许多缺陷，尤其是缝隙连接细胞间通讯（GJIC）。据报道，随着癌细胞的进展，GJIC会减弱。缝隙连接是由连接蛋白组成的细胞间通道，介导小分子从一个细胞直接传递到下一个细胞。它们参与细胞周期、细胞分化和细胞信号传导的调节。由于结直肠癌细胞中缝隙连接的调节丧失，本研究的目的是确定恢复GJIC对结直肠癌细胞的影响。
进行缝隙连接活性测定和蛋白质分析，以评估连接蛋白43（Cx43）过表达和小分子PQ1处理对GJIC的影响。
与对照相比，SW480结直肠癌细胞中Cx43的过表达使缝隙连接活性增加了6倍。这表明过表达Cx43可以恢复GJIC。此外，使用直接靶向缝隙连接通道的小分子PQ1来增加GJIC。200 nM的缝隙连接增强剂PQ1使SW480细胞中的缝隙连接活性增加了4倍。用200 nM PQ1处理1小时后，观察到Cx43从P0亚型转变为P2亚型。
Cx43的过表达和PQ1的处理可直接增加缝隙连接活性。这些发现为药物开发中靶向恢复缝隙连接活性提供了重要启示。
