# Targets of Reactive Lipid Species regulating DNA damage response and cell senescence

> **NIH NIH R01** · UNIVERSITY OF CHICAGO · 2020 · $370,575

## Abstract

Abstract
 Oxidative stress, ionizing radiation and chemotherapy agents including topoisomerase II (Top2) poisons
such as etoposide can all promote therapy-induced senescence. The current paradigm is that DNA damage
signaling is the common determinant of cellular senescence, whether induced by telomere erosion or
chromosomal double strand breaks. However, our recent studies have implicated lipid peroxidation and
resulting production of reactive lipid species (RLS) as key mediators of this pathway. This proposed work will
examine Top2 as the critical target of RLS that promotes accelerated senescence. Here, we will apply
biochemical and molecular tools to examine Top2 cysteine thiols as potential sites for modification by RLS
such as 4-hydroxynonenal (4-HNE). We will determine if RLS modifications induce formation of the stable
Top2-DNA cleaved complex (Top2cc), resulting in DNA double strand breaks and cellular senescence. To
directly test whether DNA damage is indeed sufficient for senescence, we will apply Cas9 and promiscuous
gRNAs as a source of "pure" double strand breaks. Further, combining Cas9-directed damage with RLS will
provide a test of whether the two signals act in the same or distinct pathways. We will also pursue proteome-
wide analysis of potential targets of RLS beyond Top2 that may regulate senescence. We will extend the work
to evaluate the role of RLS in Top2 poisoning in vivo, using syngeneic tumors in mice. We will also use genetic
depletion of senescent tumor cells formed after etoposide or radiation as a means to evaluate the relevance of
therapy-induced senescence to tumor response to genotoxic therapy. This work may establish a new
mechanism of action for etoposide and related chemotherapy agents as indirect topoisomerase poisons and
pro-senescent drugs, with potential for impacts on their clinical use, both alone and in combination with other
agents.

## Key facts

- **NIH application ID:** 9944508
- **Project number:** 5R01CA217182-04
- **Recipient organization:** UNIVERSITY OF CHICAGO
- **Principal Investigator:** Stephen J. Kron
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $370,575
- **Award type:** 5
- **Project period:** 2017-07-01 → 2022-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9944508

## Citation

> US National Institutes of Health, RePORTER application 9944508, Targets of Reactive Lipid Species regulating DNA damage response and cell senescence (5R01CA217182-04). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9944508. Licensed CC0.

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