GAP JUNCTIONAL COMMUNICATION AND TRANSFORMATION

缝隙连接是在接触区域形成的质膜结构。 相邻单元格之间。交界处由数百到数千人组成 每个蛋白质颗粒都包含一个微小的(1.5-2 nm)孔 连接相邻细胞的细胞质。通过这些渠道流动 小(小于1,000 Da)离子和分子。这种化学交通是 被称为缝隙连接细胞间通讯(GJIC)及其 人们对其功能知之甚少。许多间接证据导致了 提示GJIC的丢失以某种方式促进了细胞的生长 以及转化表型的表达。GJIC被禁止-由 某些致癌物质、生长促进剂和转化，但增强了 通过抗癌药物、生长抑制剂、分化剂和 在转化的表型逆转之后。在现在 在这项提议中，这一假设将以直接的方式得到解决。GJIC 将在未转化的细胞中被特别抑制，方法是防止 缝隙连接通道形成蛋白的转基因表达 用反义DNA。这些细胞的生长速度和对 转型将是量化的，应该得到加强。GJIC还将 在转化的细胞中通过转染腺病毒 含缝隙连接蛋白基因的细胞。这些细胞的致瘤性 将是坚定的，它们应该不会那么容易致癌。此外， GJIC抑制剂DDT促进生长和发育的能力 将对转型进行评估。激活RAS的机制 将测定癌基因表达和DDT降低GJIC。这些 研究将提供直接证据支持或反对GJIC在 细胞转化，可能提示临床应用的可能性 旨在增强GJIC的抗肿瘤治疗。

Gap junctions are plasma membrane structures formed at regions of contact between adjacent cells. The junctions consist of hundreds to thousands of proteinaceous particles that each contain a tiny (1.5-2 nm) pore linking the cytoplasm of the adjacent cells. Through these channels flow small (less than 1,000 Da) ions and molecules. This chemical traffic is known as gap junctional intercellular communication (GJIC) and its functions are poorly understood. Much indirect evidence has led to the suggestion that the loss of GJIC in some way facilitates cellular growth and expression of the transformed phenotype. GJIC is inhibited-by certain carcinogens, growth enhancers, and transformation but is enhanced by anticarcinogens, growth inhibitors, differentiating agents, and following reversal of the transformed phenotype. In the present proposal, this hypothesis will be addressed in a direct manner. GJIC will be specifically inhibited in nontransformed cells by preventing the expression of the gap junction channel-forming protein by transfection with antisense DNA. The growth rate and sensitivity of these cells to transformation will be quantified and should be enhanced. GJIC will also be specifically increased in transformed cells by transfection of the cells with gap junction protein cDNA. The tumorigenicity of these cells will be determined and they should be less tumorigenic. In addition, the ability of DDT, an inhibitor of GJIC, to enhance growth and transformation will be assessed. The mechanisms by which activated ras oncogene expression and DDT reduce GJIC will be determined. These studies will provide direct evidence for or against a role of GJIC in cellular transformation and may suggest the possible use of clinical antitumor therapies designed to enhance GJIC.