【摘要】 目的:研究bHLH家族基因中c-myc和mad1对人端粒酶逆转录酶(hTERT)启动子的转录调节。方法:采用脂质体DOTAP转染法将装载有虫荧光素酶基因的野生型hTERT启动子(Tw)和突变型hTERT启动子(Td)质粒,与含c-myc或mad1基因的质粒,以不同方式组合分别转染至膀胱癌T24细胞、EJ细胞、猴肾母COS-7细胞和人成纤维细胞,培养48h后检测各组虫荧光素酶活性。结果:在膀胱癌T24和EJ细胞中,Tw组转录活性显著高于对照组,亦高于Td组。在T24和EJ细胞中,c-myc可呈剂量依赖地上调Tw的转录活性,但负性调节Td转录;而mad1负性调节Tw转录,但上调Td的转录活性。c-myc和mad1联合可下调膀胱癌细胞Tw的转录。结论:c-myc和mad1可对hTERT启动子进行转录调节,并且高度依赖于bHLH家族基因的接合位点E-box的序列保守性。更多还原

【Abstract】 AIM: To investigate the transcription regulation of the promoter of human telomerase reverse transcriptase (hTERT) by transcription factors c-myc and [STBX]mad1. METHODS: The various plasmids including wild type hTERT (Tw) or mutant type hTERT (Td) which both harboring luciferase gene, the expression plasmids of c-myc and [STBX]mad1, and their control vectors were constructed. The plasmids were co-trans fected into bladder cancer cell lines T24, EJ and control cells COS-7 or fibrocytes by DOTAP liposome in various combining manner, respectively. The reporter gene luciferase activities in various groups were measured 48 h after transfection. RESULTS: The luciferase activities in T24 and EJ cells treated with Tw were much higher than that in COS-7 and fibrocytes cells treated with Tw, as well as higher than that in T24 and EJ cells treated with Td, respectively. In bladder cancer T24 and EJ cells, transcription factor c-myc and [STBX]mad1 positively and negatively regulated Tw expression in a dose-dependent manner. However, the effects of c-myc and [STBX]mad1 on Td were completely opposite to Tw. Combined with c-myc and [STBX]mad1, down-regulation of Tw expression was observed. CONCLUSION: c-myc and [STBX]mad1 regulates the transcriptional activity of hTERT promoter in bladder cancer cells, and the effects might highly depend on the conservative E-box sequence CACGTG.更多还原