Bond S L, Bechberger J F, Khoo N K, Naus C C
Department of Anatomy, University of Western Ontario, London, Canada.
Cell Growth Differ. 1994 Feb;5(2):179-86.
C6 glioma cells do not express the gap junction protein connexin32 or its corresponding mRNA. Very low levels of connexin43 protein and mRNA, as well as weak intercellular coupling, have been detected. Studies investigating the role of gap junctions in cell proliferation and tumorigenesis have shown that C6 cells transfected with connexin43 have increased levels of intercellular coupling and reduced cell growth (D. Zhu et al., Proc. Natl. Acad. Sci. USA, 88:1883-1887, 1991). To determine whether this growth inhibition is observed with other connexins, a full-length cDNA for connexin32 was used to transfect C6 cells. A number of transfected clones, expressing various levels of connexin32 mRNA, were obtained. Further analysis of several of these clones has shown that they have a corresponding increase in both the amount of connexin32 immunoreactivity and intercellular coupling. Thus, transfection of the C6 glioma cell line with connexin32, a gene which is normally expressed in the rat brain but not in C6 cells, produces both a functional mRNA and protein. Growth of the transfected clones was reduced in vivo. In vitro, growth of the various clones was not correlated to either levels of connexin32 expression or intercellular coupling. This is in contrast to findings in the previous study, in which cell growth was reduced in response to connexin43 expression both in vivo and in vitro in the transfected cells. These clones provide a unique system to study the role of gap junctions in cell proliferation and other tumor characteristics.
C6胶质瘤细胞不表达缝隙连接蛋白连接蛋白32或其相应的mRNA。已检测到连接蛋白43蛋白和mRNA的水平非常低，以及微弱的细胞间偶联。研究缝隙连接在细胞增殖和肿瘤发生中的作用表明，用连接蛋白43转染的C6细胞细胞间偶联水平增加，细胞生长减少（D.朱等人，《美国国家科学院院刊》，88:1883 - 1887,1991）。为了确定用其他连接蛋白是否也能观察到这种生长抑制作用，使用连接蛋白32的全长cDNA转染C6细胞。获得了一些表达不同水平连接蛋白32 mRNA的转染克隆。对其中几个克隆的进一步分析表明，它们在连接蛋白32免疫反应性的量和细胞间偶联方面都相应增加。因此，用连接蛋白32转染C6胶质瘤细胞系，该基因通常在大鼠脑中表达但不在C6细胞中表达，可产生功能性的mRNA和蛋白质。转染克隆在体内的生长减少。在体外，各种克隆的生长与连接蛋白32的表达水平或细胞间偶联均无相关性。这与先前研究的结果相反，在先前的研究中，转染细胞在体内和体外对连接蛋白43表达的反应均表现为细胞生长减少。这些克隆提供了一个独特的系统来研究缝隙连接在细胞增殖和其他肿瘤特性中的作用。
