Interplay and cooperation between GLI2 and master transcription factors promote progression of esophageal squamous cell carcinoma.

Abstract

The establishment of gene expression programs that drive cell identity is governed by tightly regulated transcription factors (TFs) that engage in auto- and cross-regulation in a feedforward manner, forming core regulatory circuitries (CRCs). Here, we identify and validate an important interconnected CRC formed by three master TFs-GLI2, TP63, and RUNX1-in esophageal squamous cell carcinoma (ESCC). Furthermore, master TFs co-bind to their own and each other's super-enhancers, forming an interconnected auto-regulatory loop. Mechanistically, these master TFs occupy the majority of ESCC super-enhancers and cooperatively orchestrate the ESCC transcription program. Functionally, GLI2, a master TF, is essential for ESCC viability, migration, invasion, and the growth of xenograft tumors. Moreover, the overexpression of GLI2 is significantly associated with shorter overall survival of patients with ESCC. Downstream, this CRC apparatus coordinately regulates gene expression networks in ESCC, controlling important cancer-promoting pathways, including Hedgehog, glycolysis, and epidermal growth factor receptor signaling pathways. Together, these findings offer significant mechanistic insights into the transcriptional dysregulation in ESCC and recognize GLI2 as a potential therapeutic target and prognostic marker for ESCC. More importantly, CRC-downstream genes and signaling pathways may contain potential therapeutic targets for this malignancy.