Activation of RAS/MAPK pathway confers MCL-1 mediated acquired resistance to BCL-2 inhibitor venetoclax in acute myeloid leukemia

Qi Zhang,Ce Shi,Yulia Jitkova,Cassandra L Ramage ,Lei Han ,Priyanka Vijay,Tianyu Cai,Aaron D Schimmer ,Yingchang Mi,Jeremy Ryan ,Connie C Weng,Relja Popovic,Sergej Konoplev ,Jing Wang,Charles Lu,Courtney D Dinardo,Yanan Jia ,Bridget Riley‐Gillis ,Carlos E Bueso‐Ramos ,Vivian Ruvolo ,Sujana Ghosh,Shannon Sweeney ,Wencai Ma,Alessia Lodi,Rongqing Pan,Anthony Letaï ,Saravanan Ganesan,Stephen E Kurtz ,Helen Ma,Shaun Grosskurth ,Natalia Baran,Venkata Lokesh Battula ,Stefano Tiziani,Michael Andreeff,Haijiao Zhang,R Eric Davis ,Kenneth Dunner,Joel D Leverson ,Rose Ann Padua,Jeffery W Tyner,Marina Konopleva

doi:10.1038/s41392-021-00870-3

Abstract

Despite high initial response rates, acute myeloid leukemia (AML) treated with the BCL-2–selective inhibitor venetoclax (VEN) alone or in combinations commonly acquires resistance. We performed gene/protein expression, metabolomic and methylation analyses of isogenic AML cell lines sensitive or resistant to VEN, and identified the activation of RAS/MAPK pathway, leading to increased stability and higher levels of MCL-1 protein, as a major acquired mechanism of VEN resistance. MCL-1 sustained survival and maintained mitochondrial respiration in VEN-RE cells, which had impaired electron transport chain (ETC) complex II activity, and MCL-1 silencing or pharmacologic inhibition restored VEN sensitivity. In support of the importance of RAS/MAPK activation, we found by single-cell DNA sequencing rapid clonal selection of RAS-mutated clones in AML patients treated with VEN-containing regimens. In summary, these findings establish RAS/MAPK/MCL-1 and mitochondrial fitness as key survival mechanisms of VEN-RE AML and provide the rationale for combinatorial strategies effectively targeting these pathways.

Highlights

Acute myeloid leukemia (AML) is the most common type of adult leukemia
Genomes of VEN-RE AML cells show extensive differential methylation, and hypomethylating agent (HMA) partially reverse VEN resistance We first established in vitro acquired resistance models in 3 AML cell lines that were initially sensitive to VEN (OCI-AML2, MV-4-11, and MOLM-13)
In this study, we investigated the mechanisms of acquired resistance to VEN in AML by generating multiple isogenic pairs of parental and VEN-RE cell lines through exposure to escalating

Summary

Introduction

With chemotherapy and hematopoietic stem cell transplantation, only approximately 30% of patients with nonacute-promyelocytic leukemia (APL) forms of AML survive for more than 5 years. BCL-2 family proteins are key regulators of the mitochondrial pathway of apoptosis through regulation of outer mitochondrial membrane integrity. In response to cell death signals, the proapoptotic (“BH3-only”) BCL-2 family members (such as BIM, PUMA, and BID) are released from antiapoptotic members (such as BCL-2, MCL-1) and activate the death effectors BAX and BAK. Activated BAX and BAK oligomerize and form pores in the mitochondrial outer membrane. This process, known as mitochondrial outer membrane permeabilization, releases cytochrome c into the cytosol, which in turn activates caspase cascade that leads to apoptosis. Several studies have reported intrinsic resistance to VEN, including overexpression of antiapoptotic BCL-2 family members other than BCL-2,5 acquired mutations in the BCL-2 binding groove found in chronic lymphocytic leukemia (CLL),[6] amplifications of BCL2,2,6,7 and alterations in the mitochondria structure and metabolic changes.[8]

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Results

Conclusion