ICG-001 Epigenetic Reader Do inhibitor Suppresses Wnt/β-Catenin Signaling in Leukemic Models
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Phosphatase of regenerating liver-3 (PRL-3) functions as an oncogenic dual-specificity phosphatase frequently overexpressed in acute myeloid leukemia (AML). Elevated PRL-3 expression correlates with adverse clinical outcomes and therapeutic resistance. Loss-of-function genetic screening identified a critical vulnerability in PRL-3 overexpressing leukemic cells: a synthetic lethal interaction connecting the AKT/mTOR and Wnt/β-catenin signaling cascades. Aberrant activation of these pathways maintains leukemic stem cell populations and drives chemoresistance.
Canonical Wnt signaling depends on the stabilization and nuclear translocation of β-catenin. Inside the nucleus, β-catenin binds TCF/LEF transcription factors to recruit transcriptional coactivators. The choice between CREB-binding protein (CBP) and p300 determines the cellular response. Binding to CBP initiates transcription of genes that favor proliferation and stem cell maintenance. Conversely, interaction with p300 initiates cell differentiation pathways. In high-PRL-3 AML cells, signaling through both AKT/mTOR and Wnt/β-catenin pathways is heightened, creating an obligatory dependency on dual survival signals.
Pharmacological interception of this axis requires selective disruption of β-catenin recruitment to CBP. The small molecule ICG-001 competes specifically with β-catenin for binding to the N-terminus of CBP. Crucially, ICG-001 does not disrupt β-catenin binding to p300, maintaining structural specificity. Examination of the CREB-binding protein target profiles reveals that selective target engagement downregulates key anti-apoptotic outputs like Survivin without inducing global transcriptional toxicity.
Simultaneous inhibition of AKT/mTOR signaling using the dual PI3K/mTOR inhibitor VS-5584 collapse this parallel survival pathway. Dual blockade disrupts translational regulation via mTOR while simultaneously silencing Wnt/β-catenin transcriptional activation. Under tested in vitro assay conditions, combining VS-5584 with ICG-001 yields robust synthetic lethality. Single-agent inhibition of either cascade proves insufficient to overcome the compensatory survival signals present in high-PRL-3 AML cell lines and primary patient blasts. Co-inhibition forces cells into apoptotic pathways characterized by rapid caspase-3/7 activation, PARP cleavage, and marked loss of mitochondrial membrane potential.
Pharmacological Characterization and Synthetic Lethal Profiling
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ICG-001 inhibits Wnt/β-catenin transcription by selectively competing with β-catenin for binding to CREB-binding protein (CBP), preventing the expression of downstream survival genes such as Survivin. In high-PRL-3 acute myeloid leukemia, parallel signaling through the AKT/mTOR pathway maintains cell survival. Combining ICG-001 with dual PI3K/mTOR inhibition using VS-5584 induces synthetic lethality. Dual inhibition leads to caspase-3/7 activation, PARP cleavage, reduction of p-AKT, and regression of leukemic burden in xenograft models.
PRL-3 Overexpression Defines Sensitivity to Combined Pathway Inhibition
Stratification of acute myeloid leukemia models by PRL-3 expression status revealed distinct pharmacodynamic responses. High-PRL-3 AML cell lines demonstrated high sensitivity to co-treatment with VS-5584 and the ICG-001 Epigenetic Reader Do inhibitor. Cellular proliferation dropped sharply following dual application. Synergistic growth inhibition occurred at nanomolar to low micromolar concentrations. In contrast, low-PRL-3 cell lines exhibited negligible synergistic responses under identical experimental conditions. The observed therapeutic window depends directly on baseline PRL-3 level. This differential sensitivity emphasizes the necessity of biomarker-driven stratification when deploying combination regimens targeting PI3K/mTOR and Wnt/β-catenin pathways.
Apoptotic Signaling Cascades and Target Protein Attenuation
Biochemical profiling demonstrated rapid downregulation of essential survival effectors upon combined treatment. Phosphorylation of AKT at Ser473 was strongly suppressed by VS-5584. Concurrently, application of the ICG-001 Epigenetic Reader Do inhibitor reduced total Survivin expression. Downstream phosphorylation ceased within hours of exposure. Downregulated Survivin expression preceded the enzymatic cleavage of caspase-3, caspase-7, and PARP. Apoptotic induction proceeded in a concentration-dependent manner. Synthetic lethality was confirmed by formal combination index analyses across multiple primary patient blast samples. Intercepting both translational and transcriptional nodes effectively disabled compensatory survival networks.
Reduction of Leukemic Burden in Murine Xenografts
In vivo efficacy was verified using human high-PRL-3 AML xenograft models. Administration of the combination regimen led to significant reduction of leukemic blast burden in the bone marrow and spleen. Survival analysis demonstrated prolonged overall survival in treated mice compared to monotherapy or vehicle control groups. Bone marrow cellularity showed selective clearance of human leukemic engraftment while preserving host hematopoiesis within tolerable limits. Minimal synergistic benefit occurred in low-PRL-3 murine models, confirming biomarker dependency in vivo. These empirical observations highlight the viability of concurrent AKT/mTOR and Wnt/β-catenin targeting in specific AML cohorts.