BReast CAncer susceptibility gene 2 deficiency exacerbates oxidized LDL-induced DNA damage and endothelial apoptosis

Shweta Singh; Hien Nguyen; David Michels; Hannah Bazinet; Pratiek N Matkar; Zongyi Liu; Lilian Esene; Mohamed Adam; Antoinette Bugyei-Twum; Elizabeth Mebrahtu; Jameela Joseph; Mehroz Ehsan; Hao H Chen; Mohammad Qadura; Krishna K Singh

doi:10.14814/phy2.14481

BReast CAncer susceptibility gene 2 deficiency exacerbates oxidized LDL-induced DNA damage and endothelial apoptosis

Physiol Rep. 2020 Jul;8(13):e14481. doi: 10.14814/phy2.14481.

Authors

Shweta Singh¹, Hien Nguyen^{1

2}, David Michels¹, Hannah Bazinet¹, Pratiek N Matkar^{3

4}, Zongyi Liu¹, Lilian Esene¹, Mohamed Adam^{3

4}, Antoinette Bugyei-Twum^{3

4}, Elizabeth Mebrahtu¹, Jameela Joseph^{1

5}, Mehroz Ehsan¹, Hao H Chen^{3

4}, Mohammad Qadura^{4

6

7}, Krishna K Singh^{1

2

4

6

7

8}

Affiliations

¹ Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada.
² Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada.
³ Division of Cardiology, Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, ON, Canada.
⁴ Institute of Medical Science, University of Toronto, Toronto, ON, Canada.
⁵ Department of Biology, University of Western Ontario, London, ON, Canada.
⁶ Vascular Surgery, Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, ON, Canada.
⁷ Department of Surgery, University of Toronto, Toronto, ON, Canada.
⁸ Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada.

Abstract

Mutations in the tumor suppressor gene BRCA2 (BReast CAncer susceptibility gene 2) predispose carriers to breast, ovarian, and other cancers. In response to DNA damage, BRCA2 participates in homology-directed DNA damage repair to maintain genome stability. Genome-wide association studies have identified an association between BRCA2 single nucleotide polymorphisms and plasma-lipid levels and lipid deregulation in humans. To date, DNA damage, apoptosis, and lipid deregulation are recognized as central pathways for endothelial dysfunction and atherosclerosis; however, the role of BRCA2 in endothelial dysfunction remains to be elucidated. To determine the role of BRCA2 in endothelial dysfunction, BRCA2 was silenced in human umbilical vein endothelial cells (ECs) and assessed for markers of DNA damage, apoptosis, and endothelial function following oxidized low-density lipoprotein (oxLDL) treatment. OxLDL was found to induce significant reactive oxygen species (ROS) production in BRCA2-silenced ECs. This increase in ROS production was associated with exacerbated DNA damage evidenced by increased expression and activation of DNA double-stranded break (DSB) marker γH2AX and reduced RAD51-foci formation-an essential regulator of DSB repair. Increased DSBs were associated with enhanced expression and activation of pro-apoptotic p53 and significant apoptosis in oxLDL-treated BRCA2-silenced ECs. Loss of BRCA2 in ECs was further associated with oxLDL-induced impaired tube-forming potential and eNOS expression. Collectively, the data reveals, for the first time, a novel role of BRCA2 as a regulator of EC survival and function in the setting of oxLDL treatment in vitro. Additionally, the data provide important clues regarding the potential susceptibility of BRCA2 mutation carriers to endothelial dysfunction, atherosclerosis, and other cardiovascular diseases.

Keywords: BRCA2; DNA damage; endothelial cell; endothelial dysfunction; oxidative stress.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Apoptosis*
BRCA2 Protein / deficiency
BRCA2 Protein / genetics*
DNA Breaks, Double-Stranded*
Human Umbilical Vein Endothelial Cells / metabolism*
Humans
Lipoproteins, LDL / metabolism*
Lipoproteins, LDL / toxicity
Male
Mice
Nitric Oxide Synthase Type III / genetics
Nitric Oxide Synthase Type III / metabolism
Reactive Oxygen Species / metabolism

Substances

BRCA2 Protein
BRCA2 protein, human
Lipoproteins, LDL
Reactive Oxygen Species
oxidized low density lipoprotein
Nitric Oxide Synthase Type III

Grants and funding

FRN # 153216/CIHR/Canada