# The Role of CHAF1B in Maintaining Malignant Leukemia Stem Cells

> **NIH NIH R00** · CINCINNATI CHILDRENS HOSP MED CTR · 2020 · $249,000

## Abstract

PROJECT SUMMARY
 Children with Down syndrome (DS) are at substantial risk of developing acute leukemia, which suggests
that there are leukemia promoting genes on chromosome 21. Chromatin Assembly Factor 1B (CHAF1B), which
resides in the DS critical region, is a member of the heterotrimeric CAF1 chromatin assembly complex that is
responsible for depositing H3/H4 heterodimers at the replication fork during S-phase. CHAF1B levels are
elevated in DS-AML patient samples, as well as non-DS AML cell lines and primary AML samples when
compared to healthy samples. While elevated expression is associated with poor prognosis in most tumors, the
mechanism by which CHAF1B promotes leukemogenesis is unknown. My preliminary data show that CHAF1B
directly binds discrete regions of chromatin associated with promoters and enhancers of myeloid differentiation
genes. Deletion of Chaf1b in myeloid leukemia cells results in replacement of CHAF1B on the chromatin with
the pro-differentiation transcription factors including CEBPA and the subsequent activation of a myeloid
differentiation transcriptional program. Therefore, I propose that CHAF1B is required to maintain the
undifferentiated state of MLL-AF9 leukemic cells through a role as a transcriptional regulator. In this proposal, I
will study the mechanism of CHAF1B-dependent maintenance of leukemic stem cells. The central hypothesis is
CHAF1B maintains the undifferentiated state of myeloid leukemic cells by competing for chromatin occupancy
with transcription factors at the promoters and enhancers of differentiation genes. This competition leads to
reduced expression of these genes and the resulting maintenance of the leukemic blast phenotype.
 In Aim 1, I will explore the mechanism of how the different domains of the CHAF1B protein contribute to
maintaining the undifferentiated state of myeloid leukemic cells. Then, in Aim 2, I will establish CHAF1B as a
therapeutic target in AML (including DS-AML) by determining its contribution to the progression of hematologic
tumors in vivo and primary human patient samples in vitro. My ultimate goal is to use the information gained
during the K99/R00 award to develop novel small molecule compounds that can block CHAF1B function and
control AML tumors in vivo by differentiation. My career goal is to become an independent investigator and leader
in the field of chromatin assembly and its effects on hematopoietic malignancies with the ultimate goal of
developing new therapeutic strategies to treat leukemia. During the mentored K99 phase, my main technical
goal is to become proficient at analysis of large-scale NGS data sets and basic proteomics. The impact of the
K99 phase will be enhanced by my collaborations with Dr. Scott Armstrong at Dana Farber Cancer Center at
Harvard University and Dr. Yubin Ge at Wayne State University, by allowing me to expand my training outside
my home institution of Northwestern University. Dr. John Crispino and my advisory team will guide me through...

## Key facts

- **NIH application ID:** 10076236
- **Project number:** 4R00CA230314-02
- **Recipient organization:** CINCINNATI CHILDRENS HOSP MED CTR
- **Principal Investigator:** Andrew Volk
- **Activity code:** R00 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $249,000
- **Award type:** 4N
- **Project period:** 2020-06-01 → 2023-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10076236

## Citation

> US National Institutes of Health, RePORTER application 10076236, The Role of CHAF1B in Maintaining Malignant Leukemia Stem Cells (4R00CA230314-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10076236. Licensed CC0.

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