Impaired trafficking of connexins in androgen-independent human prostate cancer cell lines and its mitigation by α-catenin
Impaired trafficking of connexins in androgen-independent human prostate cancer cell lines and its mitigation by α-catenin
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DOI：
10.1074/jbc.m202652200
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发表时间：
2002-12-20
影响因子：
4.8
通讯作者：
Mehta, PP
中科院分区：
文献类型：
--
作者：
Govindarajan, R;Zhao, S;Mehta, PP
缝隙连接是由连接蛋白组成的，为小分子物质在细胞间的扩散提供了直接的细胞间通讯途径。有证据表明，连接蛋白作为肿瘤抑制剂。我们以前表明，连接蛋白-43和连接蛋白-32在惰性前列腺癌细胞系LNCaP中的表达导致间隙连接形成和生长抑制。为了阐明连接蛋白在前列腺癌从雄激素依赖性向非依赖性发展中的作用，我们将连接蛋白43和连接蛋白32引入了侵袭性雄激素非依赖性细胞系PC-3。这些蛋白在PC-3细胞中的表达导致细胞内积累。蛋白质印迹分析显示缺乏Triton不溶性，斑块组装连接蛋白。与LNCaP细胞相反，在PC-3细胞中，连接蛋白不能被细胞表面生物素化，并且不存在于细胞表面衍生的内吞囊泡中，这表明向细胞表面的运输受损。在几种雄激素非依赖性前列腺癌细胞系中观察到细胞内连接蛋白的积累。α-连环蛋白的瞬时表达促进了连接蛋白向细胞表面的运输，并诱导了间隙连接组装。我们的研究结果表明，受损的运输，而不是不能形成缝隙连接，是人类前列腺癌细胞系中通信缺陷的主要原因。
Gap junctions, composed of connexins, provide a pathway of direct intercellular communication for the diffusion of small molecules between cells. Evidence suggests that connexins act as tumor suppressors. We showed previously that expression of connexin-43 and connexin-32 in an indolent prostate cancer cell line, LNCaP, resulted in gap junction formation and growth inhibition. To elucidate the role of connexins in the progression of prostate cancer from a hormone-dependent to -independent state, we introduced connexin-43 and connexin-32 into an invasive, androgen-independent cell line, PC-3. Expression of these proteins in PC-3 cells resulted in intracellular accumulation. Western blot analysis revealed a lack of Triton-insoluble, plaque-assembled connexins. In contrast to LNCaP cells, connexins could not be cell surface-biotinylated and did not reside in the cell surface derived endocytic vesicles, in PC-3 cells, suggesting impaired trafficking to the cell surface. Intracellular accumulation of connexins was observed in several androgen-independent prostate cancer cell lines. Transient expression of a-catenin facilitated the trafficking of both connexins to the cell surface and induced gap junction assembly. Our results suggest that impaired trafficking, and not the inability to form gap junctions, is the major cause of communication deficiency in human prostate cancer cell lines.