Long noncoding RNA AFAP1-AS1 promotes tumor progression and invasion by regulating the miR-2110/Sp1 axis in triple-negative breast cancer

Xiaohui Zhang,Yuntao Li,Sheng Zhang,Yidong Zhou,Songjie Shen,Yan Lin,Qiang Sun,Feng Mao,Fangyuan Li

doi:10.1038/s41419-021-03917-z

Abstract

Long noncoding ribonucleic acids (LncRNAs) have been found to be involved in the proliferation, apoptosis, invasion, migration, and other pathological processes of triple-negative breast cancer (TNBC). Expression of the lncRNA actin filament-associated protein 1 antisense RNA1 (AFAP1-AS1) has been found to be significantly higher in TNBC than in other subtypes or in normal tissue samples, but the specific mechanism by which AFAP1-AS1 affects the occurrence and development of TNBC is yet to be revealed. In this study, we used Cell Counting Kit-8 (CCK-8), colony formation, wound healing migration, Transwell invasion, and nude mouse xenograft assays to confirm the role of AFAP1-AS1 in the proliferation, migration of TNBC cells in vitro and in vivo. In addition, we performed bioinformatics analyses, reverse transcriptase quantitative polymerase chain reaction (RT-qPCR), western blot (WB), and dual-luciferase reporter assays (dual-LRA) to confirm interaction among AFAP1-AS1, micro-RNA 2110 (miR-2110), and Sp1 transcription factor (Sp1). We found that silencing AFAP1-AS1 and Sp1 or upregulating miR-2110 suppressed the proliferation, migration, and invasion of MDA–MB-231 and MDA–MB-468 cells in vitro as well as tumor growth in vivo. Mechanistically, the dual-LRA highlighted that miR-2110 was an inhibitory target of AFAP1-AS1, and that AFAP1-AS1 functioned as a miR-2110 sponge to increase Sp1 expression. AFAP1-AS1 silencing led to a reduction in Sp1 mRNA and protein levels, which could be reversed by joint transfection with miR-2110 inhibitor. Our findings demonstrated that AFAP1-AS1 could modulate the progression of breast cancer cells and affect tumorigenesis in mice by acting as a miR-2110 sponge, resulting in regulation of Sp1 expression. Therefore, AFAP1-AS1 could play a pivotal role in the treatment of TNBC.

Highlights

Breast cancer (BC) is one of the most common cancers among women worldwide
Double luciferase reporter qPCR) results showed that AFAP1-AS1 was significantly upregu- assays were carried out via transfecting MDA–MB-231 lated in three triple-negative breast cancer (TNBC) cell lines
Compared with that of mutant plasmid, In addition, we verified the level of AFAP1-AS1 expression in luciferase reporter activity was significantly decreased by miR

Summary

Introduction

Data showed that BC accounted for 24.5% of newly diagnosed cancer cases and was the cause of 15.5% of cancer deaths in women during 2020 [1]. It is urgent to further understand the molecular mechanism of TNBC tumor progression, and to develop experimental targets with potential clinical application, as well as to formulate more effective clinical treatment strategies and improve the prognoses of patients [2]. Of such experimental targets, RNA-based cancer treatment methods have gradually moved from concept to reality. Noncoding RNAs (ncRNAs) block mRNA function by inhibiting its transcription and binding to proteins, which exerts clinically therapeutic effects on tumors [3, 4]

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Conclusion