# Novel Targets in Cancer Chemotherapy: Chemical Biology of Guanine Alkylation

> **NIH NIH P01** · VANDERBILT UNIVERSITY · 2021 · $1,435,785

## Abstract

DNA alkylating agents, including nitrogen mustards (NM) such as cyclophosphamide (CPA), remain in
heavy use as anti-cancer agents. They are employed in adjuvant chemotherapy regimens, such as the
AC (anthracycline-CPA) therapy frequently administered to breast cancer patients. The primary site of
alkylation in DNA is the N7-guanine position. This Program focuses upon chemistry and biology that
happens after N7-dG alkylation: the NM N7-alkylated guanines undergo interstrand cross-link formation
(ICL), base-induced ring-opening, yielding stable alkyl-formamidopyrimidine (N5-substituted-Fapy)
lesions, and depurination, yielding apurinic (AP) sites. These types of complex DNA damage are may
contribute substantially to the mechanisms of action of NM agents, including cytoxicity. Knowledge of the
spectrum of complex DNA damage created by NM agents during therapy and the biological processing
of this damage is critical for the design of effective treatment regimens. We have shown that the
anthracyline antibiotic doxorubicin (Adriamycin), a component of AC therapy, forms covalent conjugates
with AP sites, a previously unrecognized activity for this drug. Thus, AP sites formed as a consequence
of NM treatment or as base excision repair (BER) intermediates provide targets for adjuvant therapies
designed to increase cytotoxicity. Complex DNA damage arising from rearrangement of N7-dG alkylation
sites has until now been understudied, in part, due to an inability to rigorously prepare DNAs containing
such damage for biological, biochemical, and structural studies. Insights gained from our Program will
yield fundamental and applied understanding of complex DNA damage arising from DNA alkylation and
its detection in cellular DNA, innovative syntheses for the production and characterization of DNAs
containing site-specific complex damage, structural understanding of how complex damage and AP site
conjugation products alters DNA structure, and modulates repair and replication, effective design of
anthracycline analogs targeted to AP sites, new biomarkers and analytical methods with which to monitor
real time therapeutic efficacy in patients undergoing chemotherapy, and improved adjuvant therapy
regimens designed to maximize cytotoxic response in cancer vs normal cells.

## Key facts

- **NIH application ID:** 10220861
- **Project number:** 5P01CA160032-29
- **Recipient organization:** VANDERBILT UNIVERSITY
- **Principal Investigator:** Michael P Stone
- **Activity code:** P01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $1,435,785
- **Award type:** 5
- **Project period:** 1997-08-01 → 2023-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10220861

## Citation

> US National Institutes of Health, RePORTER application 10220861, Novel Targets in Cancer Chemotherapy: Chemical Biology of Guanine Alkylation (5P01CA160032-29). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10220861. Licensed CC0.

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