Amino Acid Stress Response Genes Promote L-Asparaginase Resistance in Pediatric Acute Lymphoblastic Leukemia
Authors: Ferguson Daniel , McCorkle J. Robert , Dong Qian , Bonten Erik , Yang Wenjian , Bergeron Brennan P. , Autry Robert J , Diedrich Jonathan , Gocho Yoshihiro , Bajpai Richa , Crews Kristine R. , Pruett-Miller Shondra M. , Roberts Kathryn G , Stock Wendy , Mullighan Charles G. , Inaba Hiroto , Jeha Sima , Pui Ching-Hon , Yang Jun J. , Relling Mary V. , Evans William E. , Savic Daniel 
Published: November 2021

Abstract

Understanding the genomic and epigenetic mechanisms of drug resistance in pediatric acute lymphoblastic leukemia (ALL) is critical for further improvements in treatment outcome. The role of transcriptomic response in conferring resistance to l-asparaginase (LASP) is poorly understood, beyond asparagine synthetase (ASNS). We defined reproducible LASP response genes in LASP resistant and sensitive ALL cell lines (n = 7) as well as primary leukemia samples from newly diagnosed patients. We identified 2219 response genes (absolute log 2FC &gt; 1.5, FDR p-value &lt;0.05) with ~16.5% being reproduced in more than one cell line. Defining target genes of the amino acid stress response related transcription factor ATF4 in ALL cell lines using ChIP-seq revealed 25% of genes that changed expression after LASP treatment were direct targets of the ATF4 transcription factor. A total of 17,117 significantly differentially bound ATF4 sites were identified (FDR p-value &lt;0.01) and 97.8% of these sites displayed an increase in ATF4 binding following LASP treatment. SLC7A11 was found to be a response gene in cell lines and patient samples as well as a direct target of ATF4. SLC7A11 was also one of only 2.4% of response genes with basal level gene expression that also correlated with LASP ex vivo resistance in primary leukemia cells from 212 newly diagnosed children enrolled on St. Jude Total Therapy 16. Experiments using chemical inhibition of SLC7A11 with sulfasalazine, gene overexpression, and partial gene knockout recapitulated LASP resistance or sensitivity in ALL cell lines. These findings show the importance of assessing changes in gene expression following treatment with an antileukemic agent for its association with drug resistance and highlights that many response genes may not differ in their basal expression in drug resistant leukemia cells.

Disclosures
Stock: Pfizer: Consultancy, Honoraria, Research Funding; amgen: Honoraria; agios: Honoraria; jazz: Honoraria; kura: Honoraria; kite: Honoraria; morphosys: Honoraria; servier: Honoraria; syndax: Consultancy, Honoraria; Pluristeem: Consultancy, Honoraria. Mullighan: Amgen: Current equity holder in publicly-traded company; Illumina: Membership on an entity's Board of Directors or advisory committees; AbbVie: Research Funding; Pfizer: Research Funding. Pui: Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; Novartis: Other: Data Monitoring Committee. Evans: Princess Máxima Center for Pediatric Oncology, Scientific Advisory Board, Chair: Membership on an entity's Board of Directors or advisory committees; BioSkryb, Inc.: Membership on an entity's Board of Directors or advisory committees; St. Jude Children's Research Hospital, Emeritus Member (began Jan 2021): Ended employment in the past 24 months.