Electrophilic fatty acids impair RAD51 function and potentiate the effects of DNA-damaging agents on growth of triple-negative breast cells
Year: 2018
Type: article
Abstract: Homologous recombination (HR)-directed DNA double-strand break (DSB) repair enables template-directed DNA repair to maintain genomic stability. RAD51 recombinase (RAD51) is a critical component of HR and facilitates DNA strand exchange in DSB repair. We report here that treating triple-negative breast cancer (TNBC) cells with the fatty acid nitroalkene 10-nitro-octadec-9-enoic acid (OA-NO2) in combination with the antineoplastic DNA-damaging agents doxorubicin, cisplatin, olaparib, and γ-irradiation (IR) enhances the antiproliferative effects of these agents. OA-NO2 inhibited IR-induced RAD51 foci formation and enhanced H2A histone family member X (H2AX) phosphorylation in TNBC cells. Analyses of fluorescent DSB reporter activity with both static-flow cytometry and kinetic live-cell studies enabling temporal resolution of recombination revealed that OA-NO2 inhibits HR and not nonhomologous end joining (NHEJ). OA-NO2 alkylated Cys-319 in RAD51, and this alkylation depended on the Michael acceptor properties of OA-NO2 because nonnitrated and saturated nonelectrophilic analogs of OA-NO2, octadecanoic acid and 10-nitro-octadecanoic acid, did not react with Cys-319. Of note, OA-NO2 alkylation of RAD51 inhibited its binding to ssDNA. RAD51 Cys-319 resides within the SH3-binding site of ABL proto-oncogene 1, nonreceptor tyrosine kinase (ABL1), so we investigated the effect of OA-NO2–mediated Cys-319 alkylation on ABL1 binding and found that OA-NO2 inhibits RAD51–ABL1 complex formation both in vitro and in cell-based immunoprecipitation assays. The inhibition of the RAD51–ABL1 complex also suppressed downstream RAD51 Tyr-315 phosphorylation. In conclusion, RAD51 Cys-319 is a functionally significant site for adduction of soft electrophiles such as OA-NO2 and suggests further investigation of lipid electrophile–based combinational therapies for TNBC.
Source: Journal of Biological Chemistry
Language: English
Topic: DNA Repair Mechanisms
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
Funders: Memorial Sloan-Kettering Cancer Center, University of Pittsburgh, National Institutes of Health, National Heart, Lung, and Blood Institute, National Cancer Institute, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute of Biomedical Imaging and Bioengineering
Awards: G1210492913, G1342907914, G2004171525, G2100644281, G26910683, G453899893, G6271261405, G741073515, The Role of Peroxiredoxin1 & Reactive Oxygen Species in Breast Tumor Initiation, G9000010196, G9000016435, G9000028255, G9000052216, G9000144677, G9000162265, G9000180647, G9000193878, G9000205533, G9000261293, G956229831
OpenAlex ID: W2902711034