E75/NR1D2 Drives Malignant Tumor Progression by Integrating Hippo and Notch pathway

In order to investigate the molecular mechanisms underlying the transformation from benign tumors to malignant tumors, we profiled the transcriptomes of both benign (Scirb-/-/Wts-/-) and malignant (RasV12/Scrib-/-) drosophila tumors, in which ecdysone-induced protein 75B (Eip75B) was identified responsible for this transformation process. Since Eip75B was found functional as a transcription factor that can be activated by the nuclear receptor complex formed by the ecdysone receptor (EcR) and its partner molecule, ultraspiracle (USP), a CUT&Tag and RNA-seq combined analysis was performed by overexpressing Flag tagged Eip75B (E75-Flag) in drosophila wing disc. Results indicated the capacity of Eip75B on the binding and regulation of Hippo signaling pathway and Notch signaling pathway. These findings were validated by overexpressing Eip75B in benign tumors, where Hippo and Notch signaling target genes were found dramatically increasing their expression levels and the malignant progression of tumors were genetically relied on these two signaling pathways. Therefore, to further illustrate how Eip75B orchestrates Hippo and Notch signaling pathway to induce the transformation of benign tumors. Dozens of CUT&Tag experiments and transcriptome profiling of drosophila eye disc tumors were conducted, where a total of 175 genes were found newly bound and up-regulated when Eip75B participated in the tumors expressing Notch active form (Nact)and Myc tagged yki protein (yki-Myc). These 175 newly identified genes were then subjected to functional annotation, and Toll and Imd signaling core transcription factor Dif was indicated the downstream effector of all. Furthermore, the oncogenic function of Eip75B was found to be conserved within glioblastoma, where knocking down its mammalian homologue NR1D2 was found able to inhibit glioblastoma stem cell growth.