中文摘要：

候选抑瘤基因NGX6具有抑制结肠癌增殖和转移的作用,研究表明其为表皮生长因子受体（epidermal growth factor receptor,EGFR）的负性调控因子,并可下调JNK通路中重要分子MADD（MAP-kinase activating death domain）的表达,其抑瘤机制是否与抑制EGFR介导的JNK信号通路的活性有关？在已建立的转染NGX6的细胞模型基础上,借助蛋白质印迹（Western blot）和免疫组化方法在细胞和组织水平检测NGX6转染前后EGFR/K-ras/JNK/c-Jun/cyclin D1信号通路中重要蛋白质的表达.结果表明,NGX6转染后结肠癌细胞HT-29在裸鼠体内成瘤明显受抑,差异有统计学意义.Western blot结果显示,在结肠癌细胞中NGX6可明显下调EGFR、K-ras、p-JNK、c-Jun和cyclin D1的表达;进一步采用Western blot和免疫组化法验证NGX6在体内对上述关键分子表达的影响,发现NGX6可抑制裸鼠移植瘤组织中EGFR、K-ras、p-JNK、c-Jun和cyclin D1的表达,与体外结果一致.上述研究表明,NGX6在结肠癌中主要通过抑制EGFR介导的JNK通路的活性而发挥其抑瘤作用,该研究为深入探讨NGX6的机制提供了重要的实验依据.

英文摘要：

Previous studies indicated that NGX6, an EGFR negative regulating gene, can reverse the malignant phenotype of the colon cancer and down-regulate the expression of MADD（MAP-kinase activating death domain） which is an essential protein in the JNK pathway. All these results implied that whether NGX6 inhibits tumor growth by inactivating the EGFR-mediated JNK pathway？ Western blot and immunohistochemistry were performed to detect the expression of EGFR, K-ras, p-JNK, c-Jun and cyclin D1 in the colon caner cell line and in the tissue ofxenografts in nude mice, aiming at deciphering the effects of NGX6 on EGFR/K-ras/JNK/c-Jun/cyclin D1 pathway both in vitro and in vivo. The results showed that NGX6 re-expression considerably suppressed the growth of xenografts in the nude mice. Data from Western blot revealed that NGX6 significantly down-regulated the expression of EGFR, K-ras, p-JNK, c-Jun and cyclin D1 in the colon cancer cells. And the further analysis by immunohistochemistry and Western blot in vivo indicated that NGX6 decreased the expression of EGFR, K-ras, p-JNK, c-Jun and cyclin D1 in the xenografts in nude mice, which were consistent with in vitro observations. Such evidences suggest that the major mechanism ofNGX6 in colon cancer is negatively regulating EGFR-mediated JNK pathway, laying the experimental basis for further elucidating the mechanism ofNGX6 gene.