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Updated: Aug 21, 2025
In Vivo Inhibition of MicroRNA to Decrease Tumor Growth in Mice
Published on: August 23, 2019
Optimized thyroid transcription factor-1 core promoter-driven microRNA-7 expression effectively inhibits the growth
Shipeng Chen1,2, Lian Guan1,2, Xu Zhao1,2
1Special Key Laboratory of Gene Detection and Therapy & Base for Talents in Biotherapy of Guizhou Province, Zunyi 563000, China.
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 TTF-1 promoter), and verified the binding efficiency of NF-1 on the TTF-1 promoter by electrophoretic mobility shift assay (EMSA). As expected, the TTF-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, TTF-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.
Insights
Optimizing the thyroid transcription factor-1 (TTF-1) promoter enhances microRNA-7 (miR-7) expression, effectively inhibiting non-small-cell lung cancer (NSCLC) growth and metastasis with improved safety. This advances targeted gene therapy for lung cancer.
Area of Science:
- Molecular Biology
- Oncology
- Gene Therapy
Background:
- Targeted gene therapy using microRNA-7 (miR-7) driven by the thyroid transcription factor-1 (TTF-1) promoter shows promise for lung cancer treatment.
- Previous studies indicated that while effective, the intervention efficiency of TTF-1 promoter-driven miR-7 requires further improvement for clinical application.
Purpose of the Study:
- To identify and optimize the core promoter of TTF-1 to enhance its efficiency in driving miR-7 expression for non-small-cell lung cancer (NSCLC) therapy.
- To investigate the role of nuclear factor-1 (NF-1) in regulating the TTF-1 promoter activity and its impact on miR-7 expression and cancer cell growth.
Main Methods:
- 5' deletion assay to identify the TTF-1 core promoter region (-1299 bp to -871 bp).
- Electrophoretic mobility shift assay (EMSA) to confirm NF-1 binding to the optimized TTF-1 promoter.
- In vitro and in vivo studies using NSCLC cell lines and a murine xenograft model to assess tumor growth inhibition and metastasis.
Main Results:
- Nuclear factor-1 (NF-1) was identified as a key transcription factor activating the TTF-1 core promoter, directly influencing miR-7 expression.
- An optimized TTF-1 promoter with enhanced NF-1 binding sites significantly increased miR-7 expression, leading to potent inhibition of NSCLC cell growth and metastasis.
- The optimized promoter reduced the activity of the NADH dehydrogenase (ubiquinone) 1α subcomplex 4 (NDUFA4)/protein kinase B (Akt) pathway and showed no significant toxicity in major organs.
Conclusions:
- The optimized TTF-1 promoter provides a more effective platform for miR-7 delivery in NSCLC gene therapy.
- This approach offers a promising strategy for developing novel microRNA-based targeted therapies for clinical lung cancer treatment with enhanced efficacy and safety.
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