Koffler L, Roshong S, Kyu Park I, Cesen-Cummings K, Thompson D C, Dwyer-Nield L D, Rice P, Mamay C, Malkinson A M, Ruch R J
Department of Pathology, Medical College of Ohio, Toledo, Ohio 43699, USA.
J Cell Biochem. 2000 Sep 7;79(3):347-54. doi: 10.1002/1097-4644(20001201)79:3<347::aid-jcb10>3.0.co;2-2.
Gap junctional intercellular communication (GJIC) and connexin expression are frequently decreased in neoplasia and may contribute to defective growth control and loss of differentiated functions. GJIC, in E9 mouse lung carcinoma cells and WB-aB1 neoplastic rat liver epithelial cells, was elevated by forced expression of the gap junction proteins, connexin43 (Cx43) and connexin32 (Cx32), respectively. Transfection of Cx43 into E9 cells increased fluorescent dye-coupling in the transfected clones, E9-2 and E9-3, to levels comparable to the nontransformed sibling cell line, E10, from which E9 cells originated. Transduction of Cx32 into WB-aB1 cells also increased dye-coupling in the clone, WB-a/32-10, to a level that was comparable to the nontransformed sibling cell line, WB-F344. The cell cycle distribution was also affected as a result of forced connexin expression. The percentage of cells in G(1)-phase increased and the percentage in S-phase decreased in E9-2 and WB-a/32-10 cells as compared to E9 and WB-aB1 cells. Concomitantly, these cells exhibited changes in G(1)-phase cell cycle regulators. E9-2 and WB-a/32-10 cells expressed significantly less cyclin D1 and more p27(kip-1) protein than E9 and WB-aB1 cells. Other growth-related properties (expression of platelet-derived growth factor receptor-beta, epidermal growth factor receptor, protein kinase C-alpha, protein kinase A regulatory subunit-Ialpha, and production of nitric oxide in response to a cocktail of pro-inflammatory cytokines) were minimally altered or unaffected. Thus, enhancement of connexin expression and GJIC in neoplastic mouse lung and rat liver epithelial cells restored G(1) growth control. This was associated with decreased expression of cyclin D1 and increased expression of p27(kip-1), but not with changes in other growth-related functions.
间隙连接细胞间通讯（GJIC）和连接蛋白表达在肿瘤形成过程中常常降低，这可能导致生长控制缺陷和分化功能丧失。在E9小鼠肺癌细胞和WB-aB1肿瘤大鼠肝上皮细胞中，分别通过强制表达间隙连接蛋白连接蛋白43（Cx43）和连接蛋白32（Cx32），使GJIC得到增强。将Cx43转染到E9细胞中，可使转染克隆E9-2和E9-3中的荧光染料偶联增加到与E9细胞起源的未转化同系细胞系E10相当的水平。将Cx32转导到WB-aB1细胞中，也可使克隆WB-a/32-10中的染料偶联增加到与未转化同系细胞系WB-F344相当的水平。强制表达连接蛋白还会影响细胞周期分布。与E9和WB-aB1细胞相比，E9-2和WB-a/32-10细胞中G1期细胞的百分比增加，S期细胞的百分比降低。同时，这些细胞在G1期细胞周期调节因子方面表现出变化。与E9和WB-aB1细胞相比，E9-2和WB-a/32-10细胞中细胞周期蛋白D1的表达明显减少，而p27（kip-1）蛋白的表达更多。其他与生长相关的特性（血小板衍生生长因子受体-β、表皮生长因子受体、蛋白激酶C-α、蛋白激酶A调节亚基-Iα的表达以及对促炎细胞因子混合物的一氧化氮产生）仅有轻微改变或未受影响。因此，在肿瘤性小鼠肺和大鼠肝上皮细胞中增强连接蛋白表达和GJIC可恢复G1期生长控制。这与细胞周期蛋白D1表达降低和p27（kip-1）表达增加有关，但与其他生长相关功能的变化无关。
