Clinical research of gene therapy against digestive tract cancers by using ras suppressor mutant.

我们之前的研究表明，引入显性负H-ras突变体N116Y，在体外抑制各种类型癌细胞的生长。在本研究中，我们利用病毒载体测试了N116Y对人胰腺癌和食管癌细胞生长的抑制作用。我们将N116Y逆转录病毒表达载体pZIP-NI16Y转染到8株K-ras突变的人胰腺癌细胞系中。胰腺癌细胞系的生长受到强烈抑制，表达n116y的克隆扩散减弱，丧失了不依赖锚定的生长能力。此外，它们在体内无致瘤性。感染Nl16Y腺病毒（AdCMV-N116Y）可抑制所有食管癌细胞系的体外生长。在AdCMV-N116Y病毒感染的细胞中，进入S期的进程被明显阻断，EGF刺激后没有显示Erk2的激活。最重要的是，将AdCMV-N116Y直接注射到裸鼠食管肿瘤中，可以明显抑制肿瘤的生长。这些观察结果表明，N116Y通过抑制Erk2的激活，在体外和体内抑制人胰腺癌和食管癌细胞的生长，N116Y是基因治疗人胰腺癌和食管癌的潜在候选基因。

Our previous studies demonstrated that introduction of a dominant negative H-ras mutant, N116Y,inhibits the growth of various types of cancer cells in vitro. In this study, we testedthe efficacy of N116Y in blocking the growth of human pancreatic and esophageal cancer cells using viral vectors.We transfected an retrovirus-expression vector of N116Y,pZIP-NI16Y,into eight human pancreatic cancer cell lines with K-ras mutations. The growth of the pancreatic cancer cell lines was strongly inhibited, and the N116Y-expressing clones became less spread and lost their anchorage-independent growth ability. Furthermore, they were non-tumorigenic in vivo. Infection with Nl16Y adenovirus (AdCMV-N116Y) inhibitedthe in vitro growth of all esophageal cancer cell lines studied. In the AdCMV-N116Y virus-infected cells, progression into S phase was clearly blocked, and did not show the activation of Erk2 after EGF stimulation. Most importantly, direct injection of AdCMV-N116Y into the esophageal tumors in nude mice suppressed their growth significantly.These observations suggest that N116Y suppresses growth of human pancreatic and esophageal cancer cells in vitro and in vivo through the inhibition of Erk2 activation, and that N116Y is a potential candidate gene for gene therapy against human pancreatic and esophageal cancers.