Department of Pharmacy, Bengbu Medical College, Bengbu 233000, PR China.
Toxicology. 2013 Aug 9;310:53-60. doi: 10.1016/j.tox.2013.05.010. Epub 2013 Jun 4.
In several systems, the presence of gap junctions made of a single connexin has been shown to enhance the cytotoxicity of cisplatin. However, most gap junction channels in vivo appear to be heteromeric (composed of more than one connexin isoform). Here we explore in HeLa cells the cytotoxicity to cisplatin that is enhanced by heteromeric gap junctions composed of Cx26 and Cx32, which have been shown to be more selective among biological permeants than the corresponding homomeric channels. We found that survival and subsequent proliferation of cells exposed to cisplatin were substantially reduced when gap junctions were present than when there were no gap junctions. Functional inhibition of gap junctions by oleamide enhanced survival/proliferation, and enhancement of gap junctions by retinoic acid decreased survival/proliferation. These effects occurred only in high density cultures, and the treatments were without effect when there was no opportunity for gap junction formation. The presence of functional gap junctions enhanced apoptosis as reflected in markers of both early-stage and late-stage apoptosis. Furthermore, analysis of caspases 3, 8 and 9 showed that functional gap junctions specifically induced apoptosis by the mitochondrial pathway. These results demonstrate that heteromeric Cx26/Cx32 gap junctions increase the cytotoxicity of cisplatin by induction of apoptosis via the mitochondrial pathway.
在一些系统中，已证明由单个连接子组成的间隙连接的存在可增强顺铂的细胞毒性。然而，体内大多数间隙连接通道似乎是异源的（由一种以上的连接蛋白异构体组成）。在这里，我们在 HeLa 细胞中研究了由 Cx26 和 Cx32 组成的异源间隙连接增强顺铂细胞毒性的作用，已证明这些异源间隙连接在生物渗透性物质中比相应的同源通道更具选择性。我们发现，与不存在间隙连接的情况相比，当存在间隙连接时，暴露于顺铂的细胞的存活率和随后的增殖能力大大降低。通过油酸酰胺对间隙连接的功能抑制增强了存活率/增殖能力，而通过维甲酸增强间隙连接则降低了存活率/增殖能力。这些效应仅发生在高密度培养物中，并且当没有形成间隙连接的机会时，这些处理没有效果。功能性间隙连接的存在增强了细胞凋亡，这反映在早期和晚期细胞凋亡的标志物上。此外，对 Caspase 3、8 和 9 的分析表明，功能性间隙连接通过线粒体途径特异性地诱导细胞凋亡。这些结果表明，异源 Cx26/Cx32 间隙连接通过诱导线粒体途径的细胞凋亡来增加顺铂的细胞毒性。
