Characterization of human telomerase reverse transcriptase promoter methylation and transcription factor binding in differentiated thyroid cancer cell lines
Characterization of human telomerase reverse transcriptase promoter methylation and transcription factor binding in differentiated thyroid cancer cell lines
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DOI：
10.1002/gcc.22735
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发表时间：
2019-08-01
影响因子：
3.7
通讯作者：
Zeiger, Martha A.
中科院分区：
文献类型：
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作者：
Avin, Brittany A.;Wang, Yongchun;Zeiger, Martha A.
端粒酶逆转录酶 (TERT) 激活可以使细胞永生化，从而在癌症发展中发挥重要作用。 TERT 调节是多方面的，其启动子甲基化通过改变转录因子结合来控制表达。我们通过靶向亚硫酸氢盐测序、ChIP-qPCR 和 qRT-PCR 表征了五种分化甲状腺癌 (DTC) 细胞系和六种正常甲状腺组织样本中的 TERT 启动子甲基化、转录因子结合和 TERT 表达水平。 DTC 细胞系表达不同水平的 TERT，并表现出与其他端粒酶阳性癌细胞系中观察到的模式相似的 TERT 启动子甲基化模式。紧邻转录起始位点的最小启动子是低甲基化的，而更上游的部分则显示出密集的甲基化。相比之下，正常甲状腺组织中的 TERT 启动子大部分未甲基化，且 TERT 表达量最低。转录因子结合也受 TERT 突变状态的影响。 E-26 (ETS) 因子 GABPA 仅在 TERT 突变型 DTC 细胞中表现出 TERT 结合，并且还观察到最小启动子处的等位基因特异性甲基化模式，这可能表明最小启动子处的等位基因特异性因子招募。此外，我们还确定了高甲基化上游区域中激活剂 MYC 和 GSC 的结合位点，指出其在 TERT 调节中可能的重要性。总体而言，TERT 表达和端粒酶活性取决于多种调控机制的相互作用，包括 TERT 启动子甲基化、突变状态和转录因子的招募。这项工作探讨了这些调节机制之间的相互作用，并深入了解人类癌症中活性端粒酶的细胞控制。
Telomerase reverse transcriptase (TERT) activation plays an important role in cancer development by enabling the immortalization of cells. TERT regulation is multifaceted, and its promoter methylation has been implicated in controlling expression through alteration in transcription factor binding. We have characterized TERT promoter methylation, transcription factor binding, and TERT expression levels in five differentiated thyroid cancer (DTC) cell lines and six normal thyroid tissue samples by targeted bisulfite sequencing, ChIP-qPCR, and qRT-PCR. DTC cell lines express varying levels of TERT and exhibit TERT promoter methylation patterns similar to patterns seen in other telomerase positive cancer cell lines. The minimal promoter immediately surrounding the transcription start site is hypomethylated, while further upstream portions show dense methylation. In contrast, the TERT promoter in normal thyroid tissue is largely unmethylated throughout and expresses TERT minimally. Transcription factor binding is also affected by TERT mutation status. The E-twenty-six (ETS) factor GABPA exhibits TERT binding in the TERT mutant DTC cells only, and allele-specific methylation patterns at the minimal promoter were observed as well, which may indicate allele-specific factor recruitment at the minimal promoter. Furthermore, we identified binding sites for activators MYC and GSC in the hypermethylated upstream region, pointing to its possible importance in TERT regulation. Overall, TERT expression and telomerase activity depend on the interplay of multiple regulatory mechanisms including TERT promoter methylation, mutation status, and recruitment of transcription factors. This work explores of the interplay between these regulatory mechanisms and offers insight into cellular control of active telomerase in human cancer.