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RNA Biol. 2018;15(11):1420-1432. doi: 10.1080/15476286.2018.1539607. Epub 2018 Nov 18.

Luteolin inhibits Musashi1 binding to RNA and disrupts cancer phenotypes in glioblastoma cells.

Author information

1
a Greehey Children's Cancer Research Institute , University of Texas Health Science Center , San Antonio , TX , USA.
2
b Xiangya School of Medicine , Central South University , Hunan , China.
3
c Center for Innovative Drug Discovery , University of Texas Health Science Center , San Antonio , TX , USA.
4
d Department of Biochemistry and Structural Biology , University of Texas Health Science Center , San Antonio , TX , USA.
5
e Division of Basic Research , National Institute of Cancer (INCan) , Mexico City , Mexico.
6
f Department of Stem Cell Biology and Regenerative Medicine , Cleveland Clinic , Cleveland , OH , USA.
7
g Department of Cell Systems and Anatomy , University of Texas Health Science Center , San Antonio , TX , USA.

Abstract

RNA binding proteins have emerged as critical oncogenic factors and potential targets in cancer therapy. In this study, we evaluated Musashi1 (Msi1) targeting as a strategy to treat glioblastoma (GBM); the most aggressive brain tumor type. Msi1 expression levels are often high in GBMs and other tumor types and correlate with poor clinical outcome. Moreover, Msi1 has been implicated in chemo- and radio-resistance. Msi1 modulates a range of cancer relevant processes and pathways and regulates the expression of stem cell markers and oncogenic factors via mRNA translation/stability. To identify Msi1 inhibitors capable of blocking its RNA binding function, we performed a ~ 25,000 compound fluorescence polarization screen. NMR and LSPR were used to confirm direct interaction between Msi1 and luteolin, the leading compound. Luteolin displayed strong interaction with Msi1 RNA binding domain 1 (RBD1). As a likely consequence of this interaction, we observed via western and luciferase assays that luteolin treatment diminished Msi1 positive impact on the expression of pro-oncogenic target genes. We tested the effect of luteolin treatment on GBM cells and showed that it reduced proliferation, cell viability, colony formation, migration and invasion of U251 and U343 GBM cells. Luteolin also decreased the proliferation of patient-derived glioma initiating cells (GICs) and tumor-organoids but did not affect normal astrocytes. Finally, we demonstrated the value of combined treatments with luteolin and olaparib (PARP inhibitor) or ionizing radiation (IR). Our results show that luteolin functions as an inhibitor of Msi1 and demonstrates its potential use in GBM therapy.

KEYWORDS:

Musashi1; RNA binding protein; cancer therapy; glioblastoma; luteolin

PMID:
30362859
PMCID:
PMC6284574
[Available on 2019-11-18]
DOI:
10.1080/15476286.2018.1539607
[Indexed for MEDLINE]

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