HES1-mediated down-regulation of miR-138 sustains NOTCH1 activation and promotes proliferation and invasion in renal cell carcinoma

Shuangjie Liu, Lei Dou, Miao Miao, Xiaojun Man, Baojun Wei, Zhaowei Jiang, Yongze Ouyang, Toshinori Ozaki, Meng Yu, Yuyan Zhu

Although the aberrant activation of NOTCH1 pathway causes a malignant progression of renal cell carcinoma (RCC), the precise molecular mechanisms behind the potential action of pro-oncogenic NOTCH1/HES1 axis remain elusive. Here, we examined the role of tumor suppressive miR-138-2 in the regulation of NOTCH1-HES1-mediated promotion of RCC. This study employed bioinformatics, xenotransplant mouse models, ChIP assay, luciferase reporter assay, functional experiments, real-time PCR and Western blot analysis to explore the mechanisms of miR-138-2 in the regulation of NOTCH1-HES1-mediated promotion of RCC, and further explored miR-138-2-containing combination treatment strategies. There existed a positive correlation between down-regulation of miR-138 and the aberrant augmentation of NOTCH1/HES1 regulatory axis. Mechanistically, HES1 directly bound to miR-138-2 promoter region and thereby attenuated the transcription of miR-138-5p as well as miR-138-2-3p. Further analysis revealed that miR-138-5p as well as miR-138-2-3p synergistically impairs pro-oncogenic NOTCH1 pathway through the direct targeting of APH1A, MAML1 and NOTCH1. Collectively, our current study strongly suggests that miR-138-2 acts as a novel epigenetic regulator of pro-oncogenic NOTCH1 pathway, and that the potential feedback regulatory loop composed of HES1, miR-138-2 and NOTCH1 contributes to the malignant development of RCC. From the clinical point of view, this feedback regulatory loop might be a promising therapeutic target to treat the patients with RCC.