Effect of RNA-binding protein MSI2 deficiency on progression in triple-negative breast cancer via stabilizing TP53INP1.

Abstract

e12555 Background: The RNA-binding protein Musashi-2 (MSI2) has been implicated in the tumorigenesis and tumor progression of human cancers. This study investigated the clinical significance of MSI2 and the potential molecular mechanisms involved in triple-negative breast cancer (TNBC) progression. Methods: The Illumina sequencing platform was used to analyze the mRNA transcriptome in TNBC vs. normal tissues, while quantitative reverse transcription–polymerase chain reaction and immunohistochemistry validated MSI2 expression in breast cancer tissues and the effects of MSI2 on TNBC cells were assayed in vitro and in viv o. RNA immunoprecipitation (RIP) DNA and RNA sequencing was performed to identify the potential MSI2-targeted mRNAs. RIP and luciferase analyses were used to confirm the mRNA targets of MSI2. Results: MSI2 expression was significantly downregulated in TNBC vs. normal tissues and was associated with a poor overall survival of patients. MSI2 overexpression in vitro and in vivo inhibited TNBC cell proliferation and invasion as well as the extracellular signal-regulated kinase 1/2 (ERK1/2) activity. Molecularly, MSI2 expression promoted the stability of TP53INP1 mRNA by its interaction with the TP53INP1 mRNA 3ʹ-untranslated region. Furthermore, knockdown of TP53INP1 expression was able to reverse MSI2-induced suppression of TNBC cell invasion, whereas ectopic expression of TP53INP1 and inhibition of the ERK1/2 activity blocked MSI2 knockdown-induced TNBC cell invasion. Conclusions: The current study demonstrated that downregulated MSI2 expression was associated with TNBC progression and a poor prognosis and that MSI2 expression inhibited TNBC proliferation and invasion by induction of TP53INP1 stability and inhibition of ERK1/2 activity.