| The novel gene NGX6 is isolated by tumor laboratory of Central South University on studying nasopharyngeal carcinoma. NGX6 gene is located on the chromosome 9p21-22. The full-length of NGX6 cDNA is 2134 bp, encoding a polypeptide of 338 amino acids with a predicated molecular weight of 37 kDa. 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:in normal nasopharyngeal epithelial tissues, NGX6 was expressed in high level, while in very low level or undetectable in nasopharyngeal carcinoma biopsies and cell line. NGX6 also be 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 nasopharyngeal and 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. NGX6 protein mostly is located on cell membrane by using a GFP-NGX6 fusion protein.NGX6 contains a tyrosine residue that indicate NGX6 maybe influence the cellular signal transduction. And NGX6 contains an EGF-like domain that indicate NGX6 maybe antagonist or work in coordination with proteins with the same construction.Based on these studies, in an attempt to identify the function of NGX6, we designed the experiments:1. 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 in angiogenesis was detected by The CAM experiment and animal model. The CAM experiment and animal model showed the NGX6 gene can inhibite angiogenesis. And the express of VEGF was detected by RT-PCR, that showed the expression of VEGF was down-regulated by NGX6 gene. And there are metastasis in lung of mice were confirmed by hematoxylin-eosin staining Both in PcDNA3.1(+)/HT-29 group and HT-29 group, but there is no found in pcDNA3.1(+)/NGX6/HT-29 group. The NGX6 gene inhibited the metastasis of colon cancer.2. The effect of NGX6 on Apoptosis was detected by FCM cells were double-stained by PI/Annexin-V. There is no difference of Apoptosis between NGX6 transfected colon carcinoma cells and NGX6 untransfected colon carcinoma cell when cells are cultivated in vitro. But apoptosis level of NGX6 transfected colon carcinoma cells of xenograft tumor in nude mice is higher than that of NGX6 untransfected colon carcinoma cells. The NGX6-transfected HT-29 cell line with 5-Fu was used as the test, HT-29 cell line with 5-Fu and PDTC was used as the control. NGX6 gene obviously enhanced the effects of anti-proliferation and inducing apoptosis of 5-Fu. The express of NF-kB was detected by EMSA. And the express of NF-κB is inhibited in NGX6 transfected colon carcinoma cell groups. These experiments showed NGX6 gene can induce apoptosis of colon cancer and inhibit the expression of NF-κB.These experiments showed NGX6 gene can inhibite the expression of VEGF and NF-κB. And They also showed that NGX6 gene enhanced the effects of inducing apoptosis and anti-proliferation of colon carcinoma. But it needs more experiments to collect more evidences to understand the exact biological function of NGX6 and its role in the carcinoma.
|
PDF Full Text Request