The SRSF1/circATP5B/miR-185-5p/HOXB5 feedback loop regulates the proliferation of glioma stem cells via the IL6-mediated JAK2/STAT3 signaling pathway.

Junshuang Zhao,Zhitao Jing,Guoqing Zhang,Hao Li,Lian Chen,Jinkun Xu,Yang Jiang,Jinpeng Zhou,Haiying Zhang

doi:10.1186/s13046-021-01931-9

Abstract

BackgroundGlioma is the most common and malignant tumor of central nervous system. The tumor initiation, self-renewal, and multi-lineage differentiation abilities of glioma stem cells (GSCs) are responsible for glioma proliferation and recurrence. Although circular RNAs (circRNAs) play vital roles in the progression of glioma, the detailed mechanisms remain unknown.MethodsqRT-PCR, western blotting, immunohistochemistry, and bioinformatic analysis were performed to detect the expression of circATP5B, miR-185-5p, HOXB5, and SRSF1. Patient-derived GSCs were established, and MTS, EDU, neurosphere formation, and limiting dilution assays were used to detect the proliferation of GSCs. RNA-binding protein immunoprecipitation, RNA pull-down, luciferase reporter assays, and chromatin immunoprecipitation assays were used to detect these molecules’ regulation mechanisms.ResultsWe found circATP5B expression was significantly upregulated in GSCs and promoted the proliferation of GSCs. Mechanistically, circATP5B acted as miR-185-5p sponge to upregulate HOXB5 expression. HOXB5 was overexpressed in glioma and transcriptionally regulated IL6 expression and promoted the proliferation of GSCs via JAK2/STAT3 signaling. Moreover, RNA binding protein SRSF1 could bind to and promote circATP5B expression and regulate the proliferation of GSCs, while HOXB5 also transcriptionally regulated SRSF1 expression.ConclusionsOur study identified the SRSF1/circATP5B/miR-185-5p/HOXB5 feedback loop in GSCs. This provides an effective biomarker for glioma diagnosis and prognostic evaluation.

Highlights

Glioma is the most common and malignant tumor of central nervous system
The stem cell markers of GSCs were detected by immunofluorescence staining of CD133 (#ab216323, Abcam Technology, Cambridge, UK) and nestin antibodies (#ab105389, Abcam), and the multi-lineage differentiation capacity of GSCs was detected by immunofluorescence staining of GFAP (#ab7260, Abcam) and βIII tubulin (#ab18207, Abcam). Real-Time Quantitative Reverse Transcription PCR (qRT-PCR) was performed to detect the expression of circATP5B in glioma stem cells with different times of passage to ensure the stability of circATP5B expression in GSCs
CircATP5B upregulation in glioma correlates with poor patient survival We first performed qRT-PCR on both glioma specimens and adjacent brain tissues, the results showed that the relative expression of circATP5B in glioma was higher than that in adjacent brain tissues (Fig. 1a)

Summary

Introduction

Glioma is the most common and malignant tumor of central nervous system. The tumor initiation, self-renewal, and multi-lineage differentiation abilities of glioma stem cells (GSCs) are responsible for glioma proliferation and recurrence. Circular RNAs (circRNAs) play vital roles in the progression of glioma, the detailed mechanisms remain unknown. Glioma is the most common and malignant tumor among central nervous system cancers and is associated with poor prognosis in patients [1, 2]. Glioma stem cells (GSCs) have been reported to be responsible for glioma and glioblastoma proliferation, therapeutic resistance, and recurrence due to their abilities in tumor initiation, self-renewal, and multi-lineage differentiation [4]. CircRNAs were proven to be involved in the cell proliferation, migration, invasion, apoptosis, and autophagy of several cancers [7,8,9,10,11]. Several circRNAs have been reported to be involved in the biological functions of glioma, little is known about the function or molecular mechanisms of the novel circRNA, circATP5B, in glioma

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