Ezrin interacts with the tumor suppressor CHL1 and promotes neuronal differentiation of human neuroblastoma.

Marzia Ognibene,Annalisa Pezzolo,Salvatore V Pizzo

doi:10.1371/journal.pone.0244069

Abstract

In a previous study, we demonstrated that CHL1, the neuronal cell adhesion molecule close homolog of L1, acts as a tumor suppressor in human neuroblastoma (NB), a still highly lethal childhood malignancy, influencing its differentiation and proliferation degree. Here we found that ezrin, one of the ERM (ezrin, radixin, moesin) proteins involved in cytoskeleton organization, strongly interacts with CHL1. The low expression of EZRIN, as well as the low expression of CHL1 and of the neuronal differentiation marker MAP2, correlates with poor outcome in NB patients. Knock-down of ezrin in HTLA-230 cell line induces neurite retraction, enhances cell proliferation and migration, and triggers anchorage-independent growth, with effects very similar to those already obtained by CHL1 silencing. Furthermore, lack of ezrin inhibits the expression of MAP2 and of the oncosuppressor molecule p53, whereas it enhances MAPK activation, all typical features of tumor aggressiveness. As already described, CHL1 overexpression in IMR-32 cell line provokes an opposite trend, but the co-silencing of ezrin reduces these effects, confirming the hypothesis that CHL1 acts in close connection with ezrin. Overall, our data show that ezrin reinforces the differentiating and oncosuppressive functions of CHL1, identifying this ERM protein as a new targetable molecule for NB therapy.

Highlights

Neuroblastoma (NB) is a rare, neural-crest derived pediatric solid tumor
We investigated the correlation between EZRIN gene expression and NB patients’ survival, considering all the disease stages defined by the International NB Staging System (INSS) [15], consulting SEQC dataset [16] from R2 Genomics Analysis and Visualization Platform
We analyzed gene expression of the neuronal differentiation marker MAP2 (Microtubule-associated protein-2) [17], whose in vitro protein levels we had already observed to be directly proportional to CHL1 expression [4]

Summary

Introduction

Neuroblastoma (NB) is a rare, neural-crest derived pediatric solid tumor. It takes origin from precursor cells of the sympathetic nervous system, preferentially develops in the adrenal medulla, and is likely to spread to other organs [1, 2]. NB patients are classified into low-, intermediate-, and high-risk categories according to the presence of clinical and biological parameters (such as age at diagnosis, MYCN amplification, recurrent segmental chromosomal aberrations, diploid DNA index, and poorly differentiated or undifferentiated histology) for therapeutic stratification [3]. We previously described how CHL1 (close homolog of L1), a neuronal cell adhesion molecule, acts as a tumor suppressor in human NB, leading to cell differentiation and to reduced tumor growth in a preclinical mouse model [4].

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Results

Conclusion