circCTIC1 promotes the self-renewal of colon TICs through BPTF-dependent c-Myc expression.

Colon tumor is a conman tumor in the world. There are various kinds of cells in colon tumor bulk, and only a small population can initiate tumor efficiently and termed as tumor-initiating cells (TICs). With self-renewal and differentiation capacities, colon TICs drive colon tumorigenesis, metastasis and relapse. However, the molecular mechanisms of colon TICs self-renewal are elusive. Here, we found that circular RNA (circCTIC1) was highly expressed in colon tumor and colon TICs. circCTIC1 knockdown impaired the self-renewal of colon TICs, and its overexpression played an opposite role. circCTIC1 promoted the expression of c-Myc and drove the self-renewal of colon TIC through c-Myc-dependent manner. circCTIC1 interacted with nuclear remodeling factor (NURF) complex, recruited NURF complex onto c-Myc promoter and finally drove the transcriptional initiation of c-Myc. Altogether, circCTIC1 drove the self-renewal of colon TICs through bromodomain PHD finger transcription factor (BPTF)-mediated c-Myc expression.