5'isomiR-183-5p|+2 elicits tumor suppressor activity in a negative feedback loop with E2F1

© 2022. The Author(s)..

BACKGROUND: MicroRNAs (miRNAs) and isomiRs play important roles in tumorigenesis as essential regulators of gene expression. 5'isomiRs exhibit a shifted seed sequence compared to the canonical miRNA, resulting in different target spectra and thereby extending the phenotypic impact of the respective common pre-miRNA. However, for most miRNAs, expression and function of 5'isomiRs have not been studied in detail yet. Therefore, this study aims to investigate the functions of miRNAs and their 5'isomiRs.

METHODS: The expression of 5'isomiRs was assessed in The Cancer Genome Atlas (TCGA) breast cancer patient dataset. Phenotypic effects of miR-183 overexpression in triple-negative breast cancer (TNBC) cell lines were investigated in vitro and in vivo by quantifying migration, proliferation, tumor growth and metastasis. Direct targeting of E2F1 by miR-183-5p|+2 was validated with a 3'UTR luciferase assay and linked to the phenotypes of isomiR overexpression.

RESULTS: TCGA breast cancer patient data indicated that three variants of miR-183-5p are highly expressed and upregulated, namely miR-183-5p|0, miR-183-5p|+1 and miR-183-5p|+2. However, TNBC cell lines displayed reduced proliferation and invasion upon overexpression of pre-miR-183. While invasion was reduced individually by all three isomiRs, proliferation and cell cycle progression were specifically inhibited by overexpression of miR-183-5p|+2. Proteomic analysis revealed reduced expression of E2F target genes upon overexpression of this isomiR, which could be attributed to direct targeting of E2F1, specifically by miR-183-5p|+2. Knockdown of E2F1 partially phenocopied the effect of miR-183-5p|+2 overexpression on cell proliferation and cell cycle. Gene set enrichment analysis of TCGA and METABRIC patient data indicated that the activity of E2F strongly correlated with the expression of miR-183-5p, suggesting transcriptional regulation of the miRNA by a factor of the E2F family. Indeed, in vitro, expression of miR-183-5p was regulated by E2F1. Hence, miR-183-5p|+2 directly targeting E2F1 appears to be part of a negative feedback loop potentially fine-tuning its activity.

CONCLUSIONS: This study demonstrates that 5'isomiRs originating from the same arm of the same pre-miRNA (i.e. pre-miR-183-5p) may exhibit different functions and thereby collectively contribute to the same phenotype. Here, one of three isomiRs was shown to counteract expression of the pre-miRNA by negatively regulating a transcriptional activator (i.e. E2F1). We speculate that this might be part of a regulatory mechanism to prevent uncontrolled cell proliferation, which is disabled during cancer progression.

Medienart:

E-Artikel

Erscheinungsjahr:

2022

Erschienen:

2022

Enthalten in:

Zur Gesamtaufnahme - volume:41

Enthalten in:

Journal of experimental & clinical cancer research : CR - 41(2022), 1 vom: 02. Juni, Seite 190

Sprache:

Englisch

Beteiligte Personen:

Li, Xiaoya [VerfasserIn]
Michels, Birgitta Elisabeth [VerfasserIn]
Tosun, Oyku Ece [VerfasserIn]
Jung, Janine [VerfasserIn]
Kappes, Jolane [VerfasserIn]
Ibing, Susanne [VerfasserIn]
Nataraj, Nishanth Belugali [VerfasserIn]
Sahay, Shashwat [VerfasserIn]
Schneider, Martin [VerfasserIn]
Wörner, Angelika [VerfasserIn]
Becki, Corinna [VerfasserIn]
Ishaque, Naveed [VerfasserIn]
Feuerbach, Lars [VerfasserIn]
Heßling, Bernd [VerfasserIn]
Helm, Dominic [VerfasserIn]
Will, Rainer [VerfasserIn]
Yarden, Yosef [VerfasserIn]
Müller-Decker, Karin [VerfasserIn]
Wiemann, Stefan [VerfasserIn]
Körner, Cindy [VerfasserIn]

Links:

Volltext

Themen:

Cell cycle
E2F1
E2F1 Transcription Factor
E2F1 protein, human
IsomiRs
Journal Article
MiR-183-5p
MicroRNAs
Triple-negative breast cancer

Anmerkungen:

Date Completed 06.06.2022

Date Revised 16.07.2022

published: Electronic

Citation Status MEDLINE

doi:

10.1186/s13046-022-02380-8

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM341772879