Small-molecule inhibitor of AF9/ENL-DOT1L/AF4/AFF4 interactions suppresses malignant gene expression and tumor growth.

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.

• Authors: Fangrui Wu, Shenyou Nie, Yuan Yao, Tong Huo, Xin Li, Xiaowei Wu, Jidong Zhao, Yi-Lun Lin, Yinjie Zhang, Qianxing Mo, Yongcheng Song
• Journal: Theranostics (Theranostics) Vol. 11 Issue 17 Pg. 8172-8184 ( 2021) ISSN: 1838-7640 [Electronic] Australia
• PMID: 34373735 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: © The author(s).

Chemical References

• AFF4 protein, human
• Antineoplastic Agents
• Oncogene Proteins, Fusion
• Transcriptional Elongation Factors
• DOT1L protein, human
• Dot1l protein, mouse
• Histone-Lysine N-Methyltransferase

Topics

• Animals
• Antineoplastic Agents (pharmacology)
• Gene Expression (drug effects)
• Histone-Lysine N-Methyltransferase (chemistry, drug effects, genetics)
• Leukemia, Myeloid, Acute (drug therapy, genetics)
• Mice
• Oncogene Proteins, Fusion (chemistry, drug effects, genetics)
• Oncogenes (drug effects)
• Protein Interaction Domains and Motifs
• Transcriptional Elongation Factors (chemistry, drug effects, genetics)