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Journal of Zhejiang University SCIENCE B
ISSN 1673-1581(Print), 1862-1783(Online), Monthly
2022 Vol.23 No.11 P.915-930
Optimized thyroid transcription factor-1 core promoter-driven microRNA-7 expression effectively inhibits the growth of human non-small-cell lung cancer cells
Abstract: Targeted gene therapy has become a promising approach for lung cancer treatment. In our previous work, we reported that the targeted expression of microRNA-7 (miR-7) operated by thyroid transcription factor-1 (TTF-1) promoter inhibited the growth of human lung cancer cells in vitro and in vivo; however, the intervention efficiency needed to be further improved. In this study, we identified the core promoter of TTF-1 (from -1299 bp to -871 bp) by 5' deletion assay and screened out the putative transcription factors nuclear factor-1 (NF-1) and activator protein-1 (AP-1). Further analysis revealed that the expression level of NF-1, but not AP-1, was positively connected with the activation of TTF-1 core promoter in human non-small-cell lung cancer (NSCLC) cells. Moreover, the silencing of NF-1 could reduce the expression level of miR-7 operated by TTF-1 core promoter. Of note, we optimized four distinct sequences to form additional NF-1-binding sites (TGGCA) in the sequence of TTF-1 core promoter (termed as optTTF-1 promoter), and verified the binding efficiency of NF-1 on the optTTF-1 promoter by electrophoretic mobility shift assay (EMSA). As expected, the optTTF-1 promoter could more effectively drive miR-7 expression and inhibit the growth of human NSCLC cells in vitro, accompanied by a reduced transduction of NADH dehydrogenase (ubiquinone) 1α subcomplex 4 (NDUFA4)/protein kinase B (Akt) pathway. Consistently, optTTF-1 promoter-driven miR-7 expression could also effectively abrogate the growth and metastasis of tumor cells in a murine xenograft model of human NSCLC. Finally, no significant changes were detected in the biological indicators or the histology of some important tissues and organs, including heart, liver, and spleen. On the whole, our study revealed that the optimized TTF-1 promoter could more effectively operate miR-7 to influence the growth of human NSCLC cells, providing a new basis for the development of microRNA-based targeting gene therapy against clinical lung cancer.
Key words: Lung cancer; Thyroid transcription factor-1 (TTF-1); Promoter; MicroRNA-7 (miR-7); Nuclear factor-1 (NF-1)
1贵州省基因检测与治疗特色重点实验室暨贵州省生物治疗人才基地，中国遵义市，563000
2遵义医科大学免疫学教研室，中国遵义市，563000
3遵义医科大学医学物理系，中国遵义市，563000
4遵义医科大学生理学教研室，中国遵义市，563000
概要：靶向基因治疗是一种很有前景的肺癌治疗方法。在前期工作中，我们报道了由甲状腺转录因子-1（TTF-1）启动子调控微小RNA-7（miR-7）的靶向表达可在体外和体内抑制人肺癌细胞的生长，但干预效率有待进一步提高。在本研究中，我们通过5’缺失分析鉴定了TTF-1的核心启动子（从−1299 bp到−871 bp），并筛选出潜在的结合转录因子核因子-1（NF-1）和激活蛋白-1（AP-1）。进一步分析的结果表明：NF-1的表达水平，而非AP-1的表达水平，与人非小细胞肺癌（NSCLC）细胞中TTF-1核心启动子的活性呈正相关。此外，NF-1的沉默可以降低由TTF-1核心启动子调控的miR-7的表达。重要的是，我们在TTF-1核心启动子的序列上优化了四个不同的序列（称为optTTF-1启动子）以形成额外的NF-1结合位点（TGGCA），并通过电泳迁移率实验（EMSA）分析验证了NF-1对optTTF-1启动子的结合效率。通进一步研究，结果显示optTTF-1启动子可更有效地驱动miR-7表达并在体外抑制人NSCLC细胞的生长，同时减少Ⅰ型辅酶脱氢酶1α亚复合物4（NDUFA4）/蛋白激酶B（Akt）通路转导。optTTF-1启动子驱动的miR-7表达同样也可有效地抑制人NSCLC异种移植模型中肿瘤细胞的体内生长和转移。最后，模型动物的心脏、肝脏和脾脏等重要组织和器官的生物学指标和组织学未见明显变化。总之，本研究揭示了优化的TTF-1启动子可更有效地调控miR-7表达来抑制人NSCLC细胞的生长，为开发基于miRNA的靶向基因治疗临床肺癌提供了新的实验基础。
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DOI:
10.1631/jzus.B2200116
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On-line Access:
2022-11-15
Received:
2022-03-08
Revision Accepted:
2022-07-22
Crosschecked:
2022-11-16