Regulation of sarcomagenesis by the empty spiracles homeobox genes EMX1 and EMX2

Manuel Pedro Jimenez-García,Amancio Carnero,Antonio Lucena-Cacace,Daniel Otero-Albiol

doi:10.1038/s41419-021-03801-w

Abstract

The EMX (Empty Spiracles Homeobox) genes EMX1 and EMX2 are two homeodomain gene members of the EMX family of transcription factors involved in the regulation of various biological processes, such as cell proliferation, migration, and differentiation, during brain development and neural crest migration. They play a role in the specification of positional identity, the proliferation of neural stem cells, and the differentiation of certain neuronal cell phenotypes. In general, they act as transcription factors in early embryogenesis and neuroembryogenesis from metazoans to higher vertebrates. The EMX1 and EMX2’s potential as tumor suppressor genes has been suggested in some cancers. Our work showed that EMX1/EMX2 act as tumor suppressors in sarcomas by repressing the activity of stem cell regulatory genes (OCT4, SOX2, KLF4, MYC, NANOG, NES, and PROM1). EMX protein downregulation, therefore, induced the malignance and stemness of cells both in vitro and in vivo. In murine knockout (KO) models lacking Emx genes, 3MC-induced sarcomas were more aggressive and infiltrative, had a greater capacity for tumor self-renewal, and had higher stem cell gene expression and nestin expression than those in wild-type models. These results showing that EMX genes acted as stemness regulators were reproduced in different subtypes of sarcoma. Therefore, it is possible that the EMX genes could have a generalized behavior regulating proliferation of neural crest-derived progenitors. Together, these results indicate that the EMX1 and EMX2 genes negatively regulate these tumor-altering populations or cancer stem cells, acting as tumor suppressors in sarcoma.

Highlights

Sarcomas are a type of tumor affecting a low percentage of the population and are malign and commonly highly aggressive
EMX represses tumorigenic properties in sarcoma To explore the role of EMX, we first selected three different low-passage sarcoma cell lines from different tissues of origin; two sarcoma lines expressed low levels of EMX1 and EMX2 (Supplementary Fig. S1), as models to study the effects of EMX overexpression: AA and AW
Oct[4], Sox[2], Klf[4], and Myc mRNA levels in the mice with a functional allele of Emx(+/−) and especially in the null Emx(−/−), with higher levels in the induced sarcoma compared to the control muscle tissue (Fig. 7). These results indicate that the reduction of Emx1/Emx[2] allows the expression of genes related to the properties of stem cells (Nanog, Nes, Oct[4], Sox[2], Klf[4], and Myc), confirming this overexpression in the case of induced sarcomas and in the null murine models of both genes

Summary

Introduction

Sarcomas are a type of tumor affecting a low percentage of the population and are malign and commonly highly aggressive. The EMX1/EMX2 proteins are members of the EMX family of transcription factors, primarily confined to the developing brain, where they play a role in the specification of positional identity, the proliferation of neural stem cells, and the differentiation of certain neuronal cell phenotypes[17]. These genes are involved in establishing the regional pattern of the anterior brain, directly intervening in neural precursors. The overexpression of the Emx[2] gene in ANSCs has an antiproliferative effect but does not influence a particular differentiation pathway

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Results

Conclusion