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Supplementary Figure Legends from The BRCA1-Δ11q Alternative Splice Isoform Bypasses Germline Mutations and Promotes Therapeutic Resistance to PARP Inhibition and Cisplatin

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posted on 2023-03-31, 00:23 authored by Yifan Wang, Andrea J. Bernhardy, Cristina Cruz, John J. Krais, Joseph Nacson, Emmanuelle Nicolas, Suraj Peri, Hanneke van der Gulden, Ingrid van der Heijden, Shane W. O'Brien, Yong Zhang, Maribel I. Harrell, Shawn F. Johnson, Francisco J. Candido Dos Reis, Paul D. P. Pharoah, Beth Karlan, Charlie Gourley, Diether Lambrechts, Georgia Chenevix-Trench, Håkan Olsson, Javier J. Benitez, Mark H. Greene, Martin Gore, Robert Nussbaum, Siegal Sadetzki, Simon A. Gayther, Susanne K. Kjaer, Alan D. D'Andrea, Geoffrey I. Shapiro, David L. Wiest, Denise C. Connolly, Mary B. Daly, Elizabeth M. Swisher, Peter Bouwman, Jos Jonkers, Judith Balmaña, Violeta Serra, Neil Johnson

Legend for Supplementary Figures S1-S6.

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NIH

FCCC

Susan G. Komen

Wendy Feuer Ovarian Cancer Research

Salut Carlos III

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ARTICLE ABSTRACT

Breast and ovarian cancer patients harboring BRCA1/2 germline mutations have clinically benefitted from therapy with PARP inhibitor (PARPi) or platinum compounds, but acquired resistance limits clinical impact. In this study, we investigated the impact of mutations on BRCA1 isoform expression and therapeutic response. Cancer cell lines and tumors harboring mutations in exon 11 of BRCA1 express a BRCA1-Δ11q splice variant lacking the majority of exon 11. The introduction of frameshift mutations to exon 11 resulted in nonsense-mediated mRNA decay of full-length, but not the BRCA1-Δ11q isoform. CRISPR/Cas9 gene editing as well as overexpression experiments revealed that the BRCA1-Δ11q protein was capable of promoting partial PARPi and cisplatin resistance relative to full-length BRCA1, both in vitro and in vivo. Furthermore, spliceosome inhibitors reduced BRCA1-Δ11q levels and sensitized cells carrying exon 11 mutations to PARPi treatment. Taken together, our results provided evidence that cancer cells employ a strategy to remove deleterious germline BRCA1 mutations through alternative mRNA splicing, giving rise to isoforms that retain residual activity and contribute to therapeutic resistance. Cancer Res; 76(9); 2778–90. ©2016 AACR.

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    Cancer Research

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    Keywords

    Drug MechanismsCellular responses to anticancer drugsOncogenes & Tumor SuppressorsBRCA family

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