The Role of NGX6 Gene on Apoptosis of Human Colon Cancer

The novel gene NGX6 is solated by tumor laboratory of Central South University on studying nasopharyngeal carcinoma. NGX6 protein includes two transmemberane regions. There are an EGF-like domain signature and three potential N-glycosylation sites in the extracellular domain of it. The short cytoplasm contains a tyrosine residue that is a potential phsophorylation site by tyrosine kinase. Previous study on NGX6 showed: NGX6 was found down-regulated in colorectal carcinomas, and expression of NGX6 was down-regulated in, the tumors with metastasis and related to the clinic stages by using the in suit hybridization and tissue array techniques. Transfection of NGX6 into colorectal carcinomas cells can induce the reversion of some malignant phenotypes (data obtained from cell cycle, cell growth rate curve, soft agar colony formation, nude mice injection analysis, et al), the changes of gene/protein expression profiles and the down-regulation of expression of phosphor-EGFR. Based on these studies, in an attempt to identify the function of NGX6-induced-apoptosis, the following experiments were designed. The NGX6-transfected HT-29 cell line was used as the test, empty-vector- transfected HT-29 cell line and untransfected HT-29 cell line were used as the control. The effect of NGX6 on apoptosis was detected by FCM cells were double- stained by PI/Annexin-V; the express of NF-kappa B was detected by EMSA. There is no difference of apoptosis between NGX6 transfected colon carcinoma cell and NGX6 untransfected colon carcinoma cell when cells are cultivated in vitro. But apoptosis level of NGX6 transfected colon carcinoma cell of xenograft tumor in nude mice is higher than that of NGX6 untransfected colon carcinoma cell. And the express of NF-kappa B is inhibited in NGX6 transfected colon carcinoma cell groups. These experiments showed NGX6 gene can induce apoptosis of colon cancer and inhibit The express of NF-kappa B.