Abstract 6552: ZEB1-AS1 lncRNA prevents ZEB1 suppression and leads to tumor progression in undifferentiated AML subtype
Authors: Percio Stefano , Magliulo Daniela , Martini Silvia , Pasquali Sandro , Bernardi Rosa 
Published: April 2023

The zinc finger E-box binding homeobox 1 (ZEB1) transcription factor is a master regulator of the epithelial to mesenchymal transition (EMT). In solid tumors, its overexpression induces EMT, which activates cellular motility and is also associated with the maintenance of stem cell properties, driving tumor progression and metastasis. A double-negative feed-forward loop circuit has been described where, to promote EMT, ZEB1 suppresses the expression of miR-200 family members, which in turn inhibits its activity. Albeit recent evidence highlighted the existence of EMT processes also in hematological malignancies, the role of ZEB1 is not completely defined yet. Hence, this study aims to characterize ZEB1 behavior in acute myeloid leukemia (AML). To this purpose, we retrieved and analyzed RNA-Seq data from public repositories to evaluate the expression levels of the main EMT master regulator genes in normal and malignant hematopoietic cells. We observed a heterogeneous expression of these genes among AML morphological subtypes (from M0 to M5) defined by the French-American-British (FAB) classification system. Specifically, TWIST1 has the highest expression value in M3 and ZEB2 in M5, as already observed in published studies, while ZEB1 has the highest expression in M0, which significantly decreases until M5. To evaluate the ZEB1 transcriptional program, we performed a gene set enrichment analysis of hallmark signatures based on gene-wise correlation with ZEB1 among FABs that revealed the up-regulation of EMT in the M0 subtype. Moreover, the highest value of correlation was found between ZEB1 and its antisense lncRNA (ZEB1-AS1). This trait emerged as peculiar to AML both with respect to other cancer types and normal hematopoietic cells. Since ZEB1 orchestrates its transcriptional program by inhibiting the activity of specific miRNAs, we selected putative candidates that may take part in this circuit in AML by calculating their bimodality distribution, which reflects the toggle switch behavior typical of the double-negative feed-forward loop. We identified miR-425-5p, which was coherently down-regulated in M0 with respect to other FABs, and miR-151-3p which was surprisingly up-regulated. Specifically, the simultaneous up-regulation in the M0 subtype of miR-151-3p and its target ZEB1 is inconsistent with the toggle switch behavior of the circuit. Thus, we hypothesized that miR-151-3p is not able to inhibit ZEB1 expression in M0 due to the presence of ZEB1-AS1, which is supposed to disrupt the circuit mechanism protecting ZEB1 from miRNA-mediated inhibition. This hypothesis is also supported by the fact that all target genes of miR-151-3p were significantly up-regulated. A better comprehension of this regulatory circuit could allow identifying aberrant epigenetic mechanisms during leukemic development and discriminating of the different AML subtypes.

Citation Format: Stefano Percio, Daniela Magliulo, Silvia Martini, Sandro Pasquali, Rosa Bernardi. ZEB1-AS1 lncRNA prevents ZEB1 suppression and leads to tumor progression in undifferentiated AML subtype. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6552.