Molecular Modeling of Single- and Double-Hydrocarbon-Stapled Coiled-Coil Inhibitors against Bcr-Abl: Toward a Treatment Strategy for CML

J Phys Chem B. 2024 Jul 11;128(27):6476-6491. doi: 10.1021/acs.jpcb.4c02699. Epub 2024 Jul 1.

Abstract

The chimeric oncoprotein Bcr-Abl is the causative agent of virtually all chronic myeloid leukemias and a subset of acute lymphoblastic leukemias. As a result of the so-called Philadelphia chromosome translocation t(9;22), Bcr-Abl manifests as a constitutively active tyrosine kinase, which promotes leukemogenesis by activation of cell cycle signaling pathways. Constitutive and oncogenic activation is mediated by an N-terminal coiled-coil oligomerization domain in Bcr (Bcr-CC), presenting a therapeutic target for inhibition of Bcr-Abl activity toward the treatment of Bcr-Abl+ leukemias. Previously, we demonstrated that a rationally designed Bcr-CC mutant, CCmut3, exerts a dominant negative effect upon Bcr-Abl activity by preferential oligomerization with Bcr-CC. Moreover, we have shown that conjugation to a leukemia-specific cell-penetrating peptide (CPP-CCmut3) improves intracellular delivery and activity. However, our full-length CPP-CCmut3 construct (81 aa) is encumbered by an intrinsically high degree of conformational variability and susceptibility to proteolytic degradation relative to traditional small-molecule therapeutics. Here, we iterate a new generation of CCmut3 inhibitors against Bcr-CC-mediated Bcr-Abl assembly designed to address these constraints through incorporation of all-hydrocarbon staples spanning i and i + 7 positions in α-helix 2 (CPP-CCmut3-st). We utilize computational modeling and biomolecular simulation to evaluate single- and double-stapled CCmut3 candidates in silico for dynamics and binding energetics. We further model a truncated system characterized by the deletion of α-helix 1 and the flexible loop linker, which are known to impart high conformational variability. To study the impact of the N-terminal cyclic CPP toward model stability and inhibitor activity, we also model the full-length and truncated systems devoid of the CPP, with a cyclized CPP, and with an open-configuration CPP, for a total of six systems that comprise our library. From this library, we present lead-stapled peptide candidates to be synthesized and evaluated experimentally as our next iteration of inhibitors against Bcr-Abl.

MeSH terms

  • Antineoplastic Agents / chemistry
  • Antineoplastic Agents / pharmacology
  • Cell-Penetrating Peptides / chemistry
  • Cell-Penetrating Peptides / metabolism
  • Cell-Penetrating Peptides / pharmacology
  • Fusion Proteins, bcr-abl* / antagonists & inhibitors
  • Fusion Proteins, bcr-abl* / chemistry
  • Fusion Proteins, bcr-abl* / metabolism
  • Humans
  • Leukemia, Myelogenous, Chronic, BCR-ABL Positive* / drug therapy
  • Leukemia, Myelogenous, Chronic, BCR-ABL Positive* / metabolism
  • Models, Molecular
  • Molecular Dynamics Simulation
  • Protein Kinase Inhibitors / chemistry
  • Protein Kinase Inhibitors / metabolism
  • Protein Kinase Inhibitors / pharmacology

Substances

  • Fusion Proteins, bcr-abl
  • Protein Kinase Inhibitors
  • Antineoplastic Agents
  • Cell-Penetrating Peptides