Requirement of the transcription factor YB-1 for maintaining the stemness of cancer stem cells and reverting differentiated cancer cells into cancer stem cells

Fan Yang,Xiaobo Zhang,Yu Lu,Pei Cui

doi:10.1186/s13287-019-1360-4

Abstract

BackgroundCancer stem cells always express high levels of stemness-associated transcription factors to maintain their features. However, the regulatory mechanism of the stemness of cancer stem cells mediated by transcription factors has not been extensively explored.MethodsThe YB-1 gene in cancer stem cells was knocked out by the CRISPR/Cas9 system. The YB-1 knockout cancer stem cells were transfected with a vector expressing YB-1 to rescue YB-1, and then the cell proliferation, cell cycle, apoptosis, and stemness, as well as tumorigenesis in nude mice, were assessed to examine the effect of YB-1 in cancer stem cells. The target genes of YB-1 were confirmed by CHIP-seq. The totipotency or pluripotency of differentiated cancer stem cells were detected by tumorsphere formation assay and quantitative real-time PCR.ResultsThe deletion of YB-1 gene inhibited the proliferation of breast cancer stem cells and melanoma stem cells, leading to cell cycle arrest and apoptosis, and induced irreversible differentiation of cancer stem cells. The tumorigenicity ability of YB-1-deleted cancer stem cells was significantly reduced in vitro and in vivo. The results of ChIP-seq showed that YB-1 maintained the stemness of cancer stem cells by promoting the expressions of stemness-associated genes (FZD-1, p21, GLP-1, GINS1, and Notch2). Furthermore, simultaneous expressions of YB-1 and the other four (SOX2, POU3F2, OCT-4, and OLIG1) or five (SOX2, SALL2, OCT-4, POU3F2, and Bmi-1) transcription factors in YB-1 knockout cancer stem cells restored the stemness of YB-1 knockout cancer stem cells.ConclusionsOur study indicated that YB-1 was required for maintaining the stemness of cancer stem cells and reverting the differentiated tumor cells into cancer stem cells.

Highlights

Cancers composed of a heterogeneous population of cells that differ in morphology, gene expression, proliferative capacity, and invasiveness [1]
Generation of YB-1 knockout cancer stem cells using the CRISPR/Cas9 system To evaluate the role of YB-1 in cancer stem cells, the YB1 gene was knocked out in melanoma stem cells (MDAMB-435) and breast cancer stem cells (MCF-7) using the CRISPR/Cas9 system
There was no cleaved band for control cells (Fig. 1b). These results indicated that the YB-1 guide RNA (gRNA) was introduced into the genome of cancer stem cells

Summary

Introduction

Cancers composed of a heterogeneous population of cells that differ in morphology, gene expression, proliferative capacity, and invasiveness [1]. Previous studies have demonstrated that cancer stem cells are associated with treatment failure and tumor relapse in cancer [9]. Cancer stem cells maintain distinctive transcriptional programs that reflect their lineage and differentiation stage [13]. These transcriptional programs are driven by transcription factors via interactions with gene promoters [13]. Cancer stem cells are reported to exhibit specific high expression of some transcription factors [16]. Cancer stem cells always express high levels of stemness-associated transcription factors to maintain their features. The regulatory mechanism of the stemness of cancer stem cells mediated by transcription factors has not been extensively explored

Methods

Results

Discussion

Conclusion