Small molecule nitroalkenes inhibit RAD51-mediated homologous recombination and amplify triple-negative breast cancer cell killing by DNA-directed therapies.

Hong, L.; Braden, d. C.; Zhao, Y.; Skoko, J. J.; Chang, F.; Woodcock, S. R.; Uvale, C.; Casey, A.; Wood, K.; Salavatore, S.; Alp, A.; Harkness, T.; Fagunloye, A.; Razzaghi, M.; Straub, A. C.; Spies, M.; Brown, D. D.; LEE, A. V.; Schopfer, F. J.; Freeman, B. A.; Carola, C. A.

doi:10.1101/2023.08.11.552990

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bioRxiv · 10.1101/2023.08.11.552990

Small molecule nitroalkenes inhibit RAD51-mediated homologous recombination and amplify triple-negative breast cancer cell killing by DNA-directed therapies.

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Abstract

Nitro fatty acids (NO2-FAs) are endogenously generated lipid signaling mediators from metabolic and inflammatory reactions between conjugated diene fatty acids and nitric oxide or nitrite-derived reactive species. NO2-FAs undergo reversible Michael addition with hyperreactive protein cysteine thiolates to induce posttranslational protein modifications that can impact protein function. Herein, we report a novel mechanism of action of natural and non-natural nitroalkenes structurally similar to (E) 10-nitro-octadec-9-enoic acid (CP-6), recently de-risked by preclinical Investigational New Drug-enabling studies and Phase 1 and Phase 2 clinical trials and found to induce DNA damage in a TNBC xenograft by inhibiting homologous-recombination (HR)-mediated repair of DNA double-strand breaks (DSB). CP-6 specifically targets Cys319, essential in RAD51-controlled HR-mediated DNA DSB repair in cells. A nitroalkene library screen identified two structurally different nitroalkenes, a non-natural fatty acid [(E) 8-nitro- nonadec-7-enoic acid (CP-8)] and a dicarboxylate ester [dimethyl (E)nitro-oct-4-enedioate (CP- 23)] superior to CP-6 in TNBC cells killing, synergism with three different inhibitors of the poly ADP-ribose polymerase (PARP) and {gamma}-IR. CP-8 and CP-23 effectively inhibited {gamma}-IR-induced RAD51 foci formation and HR in a GFP-reported assay but did not affect benign human epithelial cells or cell cycle phases. In vivo, CP-8 and CP-23s efficacies diverged as only CP-8 showed promising anticancer activities alone and combined with the PARP inhibitor talazoparib in an HR-proficient TNBC mouse model. As preliminary preclinical toxicology analysis also suggests CP-8 as safe, our data endorse CP-8 as a novel anticancer molecule for treating cancers sensitive to homologous recombination-mediated DNA repair inhibitors. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=172 SRC="FIGDIR/small/552990v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@1dcec56org.highwire.dtl.DTLVardef@1202a09org.highwire.dtl.DTLVardef@a7e7b6org.highwire.dtl.DTLVardef@15d8925_HPS_FORMAT_FIGEXP M_FIG C_FIG

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Hong, L., Braden, d. C., Zhao, Y., Skoko, J. J., Chang, F., Woodcock, S. R., Uvale, C., Casey, A., Wood, K., Salavatore, S., Alp, A., Harkness, T., Fagunloye, A., Razzaghi, M., Straub, A. C., Spies, M., Brown, D. D., LEE, A. V., Schopfer, F. J., Freeman, B. A., Carola, C. A.. 2023-08-14. Small molecule nitroalkenes inhibit RAD51-mediated homologous recombination and amplify triple-negative breast cancer cell killing by DNA-directed therapies.. https://doi.org/10.1101/2023.08.11.552990

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