Abstract 3552: YAP-TEAD2 binding mediates therapy resistance in RAS-driven neuroblastoma
Authors: Shim Jenny , Ho Andrew , Jonus Hunter C. , Pilgrim Adeiye A. , Barwick Benjamin G. , Tang Tracy T. , Boise Lawrence H. , Goldsmith Kelly C. 
Published: April 2023

Abstract
Background/Objectives: Despite intensive multimodal therapy, greater than 50% of children with high-risk neuroblastoma (HR NB) relapse with incurable disease. Next generation sequencing of primary HR NB tumors identified an increase in activating mutations in the RAS/RAF/MAPK pathway. Moreover, gene set enrichment analyses showed a significant decrease in expression of genes suppressed by the Yes-Associated Protein (YAP) at relapse, suggesting increased YAP transcriptional repression. YAP binds with TEAD family transcription factors to regulate gene expression. We have shown that YAP promotes chemotherapy and MEK inhibitor resistance in RAS-mutated NB tumors in vivo by suppressing the expression of Harakiri (HRK), a BH3-only pro-apoptotic protein activated in response to tumor environmental stress such as serum starvation. Our overall objective is to elucidate how YAP represses HRK and tumor suppressor genes globally, and to enhance MEK inhibitor potency by combining MEK inhibition with agents that inhibit YAP or induce HRK to restore the tumor environmental stress response and apoptosis in RAS-mutated NB.
Design/Methods: We used publicly available databases to identify TEAD binding sites on the HRK gene locus in NB. To assess the global state of methylation, we treated NB cells, SK-N-AS (NRASQ61K mutation, MYCN non-amplified) and NLF (NF1 deletion, MYCN amplified), with demethylating agent azacitidine and evaluated HRK expression. To identify the specific TEAD (1-4) binding partner to YAP, we performed siRNA and co-immunoprecipitation studies. We further tested novel YAP-TEAD small molecule inhibitors with varying TEAD1-4 inhibition specificity in SK-N-AS and NLF cells in vitro.
Results: We observed that TEAD binds near cis-regulatory regions on the HRK gene locus in NB. We found that HRK expression is restored when SK-N-AS and NLF cells are treated with azacitidine despite YAP expression increasing. We also identified TEAD2 as the specific binding partner to YAP in NB and found that TEAD2 is necessary for HRK regulation. Novel YAP-TEAD small molecule inhibitors affect NB cell viability under serum-deprived conditions in vitro, especially the inhibitor with highest specificity against TEAD2, and affect YAP-TEAD downstream targets.
Conclusions: YAP-TEAD2 binding is essential for HRK regulation in RAS-mutated NB and thus is a logical therapeutic target to restore therapy response. Further studies are ongoing to test YAP-TEAD small molecule inhibitors in combination with MEK inhibitors and in vivo.
Citation Format: Jenny Shim, Andrew Ho, Hunter C. Jonus, Adeiye A. Pilgrim, Benjamin G. Barwick, Tracy T. Tang, Lawrence H. Boise, Kelly C. Goldsmith. YAP-TEAD2 binding mediates therapy resistance in RAS-driven neuroblastoma. [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 3552.