AbstractHuman telomerase reverse tr

Abstract

Human telomerase reverse transcriptase (hTERT) is upregulated in most cancer cell types as well in immortalized cells. The underlying mechanism for such upregulation, however, remains largely unknown. We report here that bile acids under acidified media increase hTERT expression via c-myc activation in primary human gastric cancer cell lines. Human gastric cancer MKN28, MGC803 and SGC7901 cells were treated with 100 µM deoxycholic acid (DCA) or chenodeoxycholic acid (CDCA) with or without acidified media in the presence or absence of the c-myc inhibitor 10058-F4 for 24 h. hTERT and c-myc protein levels were determined by western blot analysis. hTERT and c-myc mRNA levels were determined by RT-PCR. The promoter activities of hTERT and c-myc transcription were determined using promoter reporter luciferase assays for both. Telomerase enzyme activity was analyzed by stretch PCR. hTERT mRNA and protein levels were significantly increased by bile acids in acidified media and were accompanied with enhanced telomerase activity. No changes were found at a pH of 7.0 or with acidified media alone. Similarly, the mRNA and protein levels of c-myc were also increased by bile acids in acidified media but not at a pH of 7.0 or with acidified media alone. Importantly, pharmacologic inhibition of c-myc using 10058-F4 prevented hTERT induction by DCA or CDCA in gastric cancer cells under acidic conditions. Bile acids (DCA and CDCA) under acidic conditions increased hTERT expression in human gastric cancer cells by activation of c-myc transcription. This suggests that acidified bile acids may promote tumorigenesis and affect cell ageing via telomerase activation.

結果 (中文) 1:

摘要Human telomerase reverse transcriptase (hTERT) is upregulated in most cancer cell types as well in immortalized cells. The underlying mechanism for such upregulation, however, remains largely unknown. We report here that bile acids under acidified media increase hTERT expression via c-myc activation in primary human gastric cancer cell lines. Human gastric cancer MKN28, MGC803 and SGC7901 cells were treated with 100 µM deoxycholic acid (DCA) or chenodeoxycholic acid (CDCA) with or without acidified media in the presence or absence of the c-myc inhibitor 10058-F4 for 24 h. hTERT and c-myc protein levels were determined by western blot analysis. hTERT and c-myc mRNA levels were determined by RT-PCR. The promoter activities of hTERT and c-myc transcription were determined using promoter reporter luciferase assays for both. Telomerase enzyme activity was analyzed by stretch PCR. hTERT mRNA and protein levels were significantly increased by bile acids in acidified media and were accompanied with enhanced telomerase activity. No changes were found at a pH of 7.0 or with acidified media alone. Similarly, the mRNA and protein levels of c-myc were also increased by bile acids in acidified media but not at a pH of 7.0 or with acidified media alone. Importantly, pharmacologic inhibition of c-myc using 10058-F4 prevented hTERT induction by DCA or CDCA in gastric cancer cells under acidic conditions. Bile acids (DCA and CDCA) under acidic conditions increased hTERT expression in human gastric cancer cells by activation of c-myc transcription. This suggests that acidified bile acids may promote tumorigenesis and affect cell ageing via telomerase activation.

結果 (中文) 3:

摘要

人端粒酶逆转录酶（hTERT）的表达在大多数癌症细胞类型以及在永生化细胞。这种上调的基本机制，但是，仍然在很大程度上是未知的。我们在这里报告，胆汁酸在酸性介质中通过增加hTERT的表达在原发性胃癌细胞c-myc活化。人胃癌MKN28，MGC803和SGC7901细胞在100µm脱氧胆酸（DCA）治疗或鹅去氧胆酸（CDCA）或无酸性介质中c-myc抑制剂10058-F4的存在或不存在24小时hTERT及c-myc蛋白印迹法测定蛋白质含量。hTERT和c-myc基因的RT-PCR检测mRNA的表达水平。启动子活性，hTERT和c-myc基因的启动子荧光素酶检测使用记者都确定了转录。通过拉伸聚合酶链反应分析端粒酶的活性。hTERT mRNA和蛋白水平均明显增加胆汁酸在酸性介质和带有增强端粒酶活性。在pH为7或酸化媒体单独无明显变化。同样，和c-myc的表达水平也增加了胆汁酸在酸性介质而不是在pH为7或酸化媒体单独。重要的是，应用10058-F4阻止hTERT诱导DCA或CDCA胃癌细胞在酸性条件下药物抑制c-myc。胆汁酸（DCA，CDCA）在酸性条件下增加hTERT的表达在胃癌细胞中c-myc的转录激活的。这表明，酸化胆汁酸可促进肿瘤的形成和通过激活端粒酶影响细胞老化。