Theranostics 2021; 11(8):3540-3551. doi:10.7150/thno.51885

Research Paper

Aldehyde dehydrogenase inhibitors promote DNA damage in ovarian cancer and synergize with ATM/ATR inhibitors

Edward Grimley1*, Alexander J. Cole1*, Thong T. Luong2, Stacy C. McGonigal1, Sarah Sinno1, Dongli Yang1, Kara A. Bernstein2, Ronald J. Buckanovich1,3✉

1. Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, UPMC Hillman Cancer Center and the Magee-Womens Research Institute, University of Pittsburgh, Pittsburgh, PA, USA.
2. Dept of Microbiology and Molecular. Genetics, University of Pittsburgh School of Medicine, UPMC Hillman Cancer Center, Pittsburgh, PA, USA.
3. Department of Internal Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
*Contributed equally to the manuscript

This is an open access article distributed under the terms of the Creative Commons Attribution License ( See for full terms and conditions.
Grimley E, Cole AJ, Luong TT, McGonigal SC, Sinno S, Yang D, Bernstein KA, Buckanovich RJ. Aldehyde dehydrogenase inhibitors promote DNA damage in ovarian cancer and synergize with ATM/ATR inhibitors. Theranostics 2021; 11(8):3540-3551. doi:10.7150/thno.51885. Available from

File import instruction


Rationale: Aldehyde dehydrogenase (ALDH) enzymes are often upregulated in cancer cells and associated with therapeutic resistance. ALDH enzymes protect cells by metabolizing toxic aldehydes which can induce DNA double stand breaks (DSB). We recently identified a novel ALDH1A family inhibitor (ALDHi), 673A. We hypothesized that 673A, via inhibition of ALDH1A family members, could induce intracellular accumulation of genotoxic aldehydes to cause DSB and that ALDHi could synergize with inhibitors of the ATM and ATR, proteins which direct DSB repair.

Methods: We used immunofluorescence to directly assess levels of the aldehyde 4-hydroxynonenal and comet assays to evaluate DSB. Western blot was used to evaluate activation of the DNA damage response pathways. Cell counts were performed in the presence of 673A and additional aldehydes or aldehyde scavengers. ALDH inhibition results were confirmed using ALDH1A3 CRISPR knockout. Synergy between 673A and ATM or ATR inhibitors was evaluated using the Chou-Talalay method and confirmed in vivo using cell line xenograft tumor studies.

Results: The ALDHi 673A cellular accumulation of toxic aldehydes which induce DNA double strand breaks. This is exacerbated by addition of exogenous aldehydes such as vitamin-A (retinaldehyde) and ameliorated by aldehyde scavengers such as metformin and hydralazine. Importantly, ALDH1A3 knockout cells demonstrated increased sensitivity to ATM/ATR inhibitors. And, ALDHi synergized with inhibitors of ATM and ATR, master regulators of the DSB DNA damage response, both in vitro and in vivo. This synergy was evident in homologous recombination (HR) proficient cell lines.

Conclusions: ALDHi can be used to induce DNA DSB in cancer cells and synergize with inhibitors the ATM/ATR pathway. Our data suggest a novel therapeutic approach to target HR proficient ovarian cancer cells.

Keywords: aldehyde dehydrogenase, DNA damage, Ovarian cancer, ATM, ATR