Small-Molecule Inhibitor of AF9/Enl-DOT1L/AF4/AFF4 Interactions Suppresses Malignant Gene Expression and Tumor Grow

Authors

Fangrui Wu
Shenyou Nie
Yuan Yao
Tong Huo
Xin Li
Xiaowei Wu
Jidong Zhao
Yi-Lun Lin
Yinjie Zhang
Qianxing Mo
Yongcheng Song

Publication Date

1-1-2021

Journal

Theranostics

DOI

10.7150/thno.56737

PMID

34373735

PMCID

PMC8344022

PubMedCentral® Posted Date

7-13-2021

PubMedCentral® Full Text Version

Post-print

Published Open-Access

yes

Keywords

Animals, Antineoplastic Agents, Gene Expression, Histone-Lysine N-Methyltransferase, Leukemia, Myeloid, Acute, Mice, Oncogene Proteins, Fusion, Oncogenes, Protein Interaction Domains and Motifs, Transcriptional Elongation Factors, MLL-rearranged leukemia, Super elongation complexes, Protein-protein interaction, Small-molecule inhibitor, Cancer therapeutics

Abstract

Chromosome translocations involving mixed lineage leukemia (MLL) gene cause acute leukemia with a poor prognosis. MLL is frequently fused with transcription cofactors AF4 (~35%), AF9 (25%) or its paralog ENL (10%). The AHD domain of AF9/ENL binds to AF4, its paralog AFF4, or histone-H3 lysine-79 (H3K79) methyltransferase DOT1L. Formation of AF9/ENL/AF4/AFF4-containing super elongation complexes (SEC) and the catalytic activity of DOT1L are essential for MLL-rearranged leukemia. Protein-protein interactions (PPI) between AF9/ENL and DOT1L/AF4/AFF4 are therefore a potential drug target.

Methods: Compound screening followed by medicinal chemistry was used to find inhibitors of such PPIs, which were examined for their biological activities against MLL-rearranged leukemia and other cancer cells.

Results: Compound-1 was identified to be a novel small-molecule inhibitor of the AF9/ENL-DOT1L/AF4/AFF4 interaction with IC50s of 0.9-3.5 µM. Pharmacological inhibition of the PPIs significantly reduced SEC and DOT1L-mediated H3K79 methylation in the leukemia cells. Gene profiling shows compound-1 significantly suppressed the gene signatures related to onco-MLL, DOT1L, HoxA9 and Myc. It selectively inhibited proliferation of onco-MLL- or Myc-driven cancer cells and induced cell differentiation and apoptosis. Compound-1 exhibited strong antitumor activity in a mouse model of MLL-rearranged leukemia.

Conclusions: The AF9/ENL-DOT1L/AF4/AFF4 interactions are validated to be an anticancer target and compound-1 is a useful in vivo probe for biological studies as well as a pharmacological lead for further drug development.

Comments

Associated Data