Basic Investigations EXPRESSION OF GAP JUNCTION PROTEIN Cx43 IN CULTURED HUMAN NORMAL AND MALIGNANT LUNG CELLS

Gap junctional intercellular communicationexchange of small molecules and ions between contiguous cells through membranous gap junctional channelsis essential for growth control and tissue homecotasis. This work concerns the functional expression of gap junction protein connexin 43 (Cx43) in normal human lung cells and the changes in lung carcinoma cells. By. using Northern blot hybridization analysis and Cx43 immunocytochemical methods, it was otherved that cultured normal human embryonic lung cells expressed a high level of Cx43 in both mRNA and protein levels.The Cx43 immunofluorescence was localized at cell membrane regions corresponding to the location of gap junctions. These normal lung cells were competent of intercellular communication function as detected by Lucifer yellow dye transfer. In contrast to normal celis, Cx43 mRNA and protein was not detectable in the carcinoma PG cell line. These tumor cells were defective of intercellular communication function. These results demonstrate that Cx43 is expressed in normal cultured human embryonic lung cells but not in lung tumor cells. The lack of intercellular communication in the lung tumor cell line correlates with dysfunctional intercellular communication. The suggestive role of Cx as a tumor suppersor gene is discussed.

间隙连接蛋白Cx43在人胚肺和肺癌细胞表达的研究

细胞与细胞之间通过细胞膜上的间隙连接通道交换小分子和离子进行细胞间通讯，对细胞增殖分化调控和机体内环境稳定有重要作用。用间隙连接蛋白Ｃｘ４３ｃＤＮＡ探针Ｎｏｒｔｈｅｒｎ印迹杂交，Ｃｘ４３抗体免疫荧光染色和罗氏黄荧光染料传输方法检查，正常人胚肺细胞的Ｃｘ４３在ｍＲＮＡ和蛋白水平有高表达，Ｃｘ４３蛋白免疫荧光分布在间隙连接的部位，细胞间隙连接通讯功能明显。与正常相反，人肺癌ＰＧ系细胞Ｃｋ４３无论在ｍＲＮＡ或蛋白质水平都无表达，细胞通讯功能缺陷。结果表明Ｃｘ４３在培养的人胚肺细胞有功能性表达。人肺癌ＰＧ细胞通讯功能缺陷与Ｃｘ４３基因转录抑制有关。对Ｃｘ基因的抑癌基因性质进行讨论。