Related Experiment Video
Updated: Oct 19, 2025
Intracellular Phosphoflow Cytometry of Acute Myeloid Leukemia Patient-Derived Xenotransplants
Published on: June 6, 2025
ASXL1 mutations are associated with distinct epigenomic alterations that lead to sensitivity to venetoclax and
Nora E Rahmani1,2, Nandini Ramachandra1, Srabani Sahu1
1Department of Oncology, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY, USA.
Abstract:
The BCL2-inhibitor, Venetoclax (VEN), has shown significant anti-leukemic efficacy in combination with the DNMT-inhibitor, Azacytidine (AZA). To explore the mechanisms underlying the selective sensitivity of mutant leukemia cells to VEN and AZA, we used cell-based isogenic models containing a common leukemia-associated mutation in the epigenetic regulator ASXL1. KBM5 cells with CRISPR/Cas9-mediated correction of the ASXL1G710X mutation showed reduced leukemic growth, increased myeloid differentiation, and decreased HOXA and BCL2 gene expression in vitro compared to uncorrected KBM5 cells. Increased expression of the anti-apoptotic gene, BCL2, was also observed in bone marrow CD34+ cells from ASXL1 mutant MDS patients compared to CD34+ cells from wild-type MDS cases. ATAC-sequencing demonstrated open chromatin at the BCL2 promoter in the ASXL1 mutant KBM5 cells. BH3 profiling demonstrated increased dependence of mutant cells on BCL2. Upon treatment with VEN, mutant cells demonstrated increased growth inhibition. In addition, genome-wide methylome analysis of primary MDS samples and isogenic cell lines demonstrated increased gene-body methylation in ASXL1 mutant cells, with consequently increased sensitivity to AZA. These data mechanistically link the common leukemia-associated mutation ASXL1 to enhanced sensitivity to VEN and AZA via epigenetic upregulation of BCL2 expression and widespread alterations in DNA methylation.
Insights
The ASXL1 mutation in leukemia increases sensitivity to Venetoclax and Azacitidine by upregulating BCL2 expression and altering DNA methylation, offering new therapeutic insights.
Area of Science:
- Hematology
- Molecular Biology
- Epigenetics
Background:
- Venetoclax (VEN) and Azacitidine (AZA) are effective in treating leukemia.
- The ASXL1 mutation is common in leukemia and influences treatment response.
- Understanding mechanisms of drug sensitivity in mutant leukemia is crucial.
Purpose of the Study:
- To investigate the mechanisms behind selective sensitivity of ASXL1-mutant leukemia cells to VEN and AZA.
- To explore the role of ASXL1 mutations in BCL2 expression and DNA methylation.
- To link ASXL1 mutations to epigenetic alterations and drug response.
Main Methods:
- Utilized isogenic cell models with CRISPR/Cas9-corrected ASXL1 mutations.
- Performed gene expression analysis, ATAC-sequencing, BH3 profiling, and methylome analysis.
- Analyzed primary bone marrow samples from MDS patients with and without ASXL1 mutations.
Main Results:
- ASXL1 mutation correction reduced leukemic growth and BCL2 expression.
- ASXL1 mutant cells showed increased BCL2 expression, open BCL2 promoter chromatin, and BCL2 dependence.
- Mutant cells exhibited increased sensitivity to VEN and AZA, linked to gene-body methylation.
- ASXL1 mutant MDS patient cells showed higher BCL2 expression than wild-type.
Conclusions:
- ASXL1 mutations mechanistically enhance sensitivity to VEN and AZA.
- Epigenetic upregulation of BCL2 expression is a key mechanism.
- Widespread DNA methylation alterations in ASXL1 mutant cells contribute to drug sensitivity.
Related Concept Videos
01:37Epigenetic Regulation
X-chromosome...
01:33Pleiotropy
03:17Inheritance of Chromatin Structures
03:18Non-LTR Retrotransposons
02:23Abnormal Proliferation
02:50Combination Therapies and Personalized Medicine
The combination of the drug acetazolamide and sulforaphane is a good example of combination therapy to treat cancer. The cells in the interior of a large tumor often die due to the hypoxic and...