# Project 2: The role of the DNA damage response in clonal competition following genotoxic stress

> **NIH NIH P01** · BAYLOR COLLEGE OF MEDICINE · 2024 · $435,122

## Abstract

Project Summary/Abstract
The overall goal of Project 2 is to determine how mutations in the DNA damage response (DDR) pathway interact
with genotoxic stressors to cause clonal hematopoiesis (CH) and malignant transformation. CH is associated
with ~20 recurrently-mutated genes and an 11-fold increase in risk of hematologic malignancies. Among the
genes commonly mutated in CH are PPM1D, TP53, ATM, CHEK2, and SRCAP, all of which are involved in
DDR. This finding raises the possibility that DNA damage exerts a selective pressure allowing DDR-mutant
hematopoietic stem and progenitor cells (HSPCs) to clonally expand, causing CH. Indeed, we have shown that
murine HSPCs carrying a CH-associated Ppm1d mutation gain competitive advantage over wild-type HSPCs
after cisplatin treatment. To compare the effects of CH-associated mutations in promoting clonal expansion upon
genotoxic stressors, we created a novel CH mouse model in which five CH mutant HSPCs were co-transplanted
with wild-type HSPCs and treated recipient mice with cisplatin (termed 5x mosaic model). We found that Ppm1d
and Trp53 mutant cells outcompeted other CH mutants, such as Dnmt3a and Tet2, supporting the concept that
genotoxic stressors specifically select for DDR-mutant cells. In Project 2, we will test the hypothesis that
mutations in the DDR confer a selective advantage to HSPCs exposed to DNA damaging agents, such as
chemotherapies or cigarette smoke, which is associated with a replication error mutational signature. In Aim 1,
we will use the 5x mosaic strategy with mutations in the five common DDR genes mentioned above. We will
expose these mice to chemotherapies or cigarette smoke and determine whether particular exposures favor
specific mutant HSPCs. Although DDR mutations are found frequently in CH, they are less common in malignant
clones, raising a question as to how DDR-mutant CH promotes hematologic malignancies. Here, we will use our
novel 5x model to examine whether DDR-mutant HSPCs promote hematologic malignancies in a cell extrinsic
manner, such as by generating an environment favorable to transformed cells. Finally, in Aim 3 we will determine
whether interventions targeting apoptosis, inflammation, or oxidative stress mitigate CH and its risk of
transformation to hematologic malignancy. This Project is highly integrated with other Projects, as it will
differentiate the effects of genotoxic stressors from other causes of inflammation by comparing data with Project
1, and it will share technical innovations with Project 1. With these models, we will be able to iteratively validate
the stressor-mutation interactions found in humans in Project 3. Results from Project 2 will provide novel insights
into how DDR mutations allow HSPCs to expand following exposure to the genotoxic stressors chemotherapy
and cigarette smoke. These mechanistic studies may reveal potential interventions against CH and, importantly,
malignant transformation. This Project will use Core A for single-cell ...

## Key facts

- **NIH application ID:** 10833502
- **Project number:** 5P01CA265748-03
- **Recipient organization:** BAYLOR COLLEGE OF MEDICINE
- **Principal Investigator:** Daisuke Nakada
- **Activity code:** P01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $435,122
- **Award type:** 5
- **Project period:** 2022-04-08 → 2027-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10833502

## Citation

> US National Institutes of Health, RePORTER application 10833502, Project 2: The role of the DNA damage response in clonal competition following genotoxic stress (5P01CA265748-03). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10833502. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*