Fig. 1: Characterization of BRCA1 in SNU-251 cells.

a MDA-MB-231, MDA-MB-436 and SNU-251 cells were cultured in the presence of vehicle (V) or 1 µM rucaparib (R) for 5 days, followed by Annexin staining and flow cytometry. ***p < 0.001, *p < 0.05 compared to vehicle. b Cells were maintained in the presence of vehicle or 1 µM rucaparib and counted every 5 days. Cell growth is expressed as a percentage of vehicle-treated cells. c MDA-MB-231, MDA-MB-436, SNU-251 parental (P), SNU-251-RR cells were seeded at decreasing densities in the presence of either vehicle, 100 nM rucaparib, 100 nM olaparib, or 100 nM niraparib and colonies counted 2-week post-seeding. Cell survival is expressed as a percentage of vehicle-treated cells. ***p < 0.001, **p < 0.01, compared to MDA-MB-231. See Supplementary Fig. 1b for representative plates as well as γ-irradiation (IR) and cisplatin treatments. d MDA-MB-231 (231), MDA-MB-436 (436), SNU-251 parental (P), SNU-251-RR (RR) cells were examined for BRCA1 protein expression using N- or C-terminal-specific antibodies by Western blot. e MDA-MB-231 (231), SNU-251-RR (SNU) cells were assessed for BRCA1 expression using N- or C-terminal-specific antibodies by Western blot. Ectopic full-length BRCA1 (FL) and BRCA1-Δexons-16–24 (Δ16) cDNA expressing MDA-MB-436 cells were used as comparators for BRCA1 isoform molecular weights. f BRCA1 was immunoprecipitated from MDA-MB-231 and SNU-251-RR cells and subject to mass spectrometry. BRCA1 exons are shown and aligned with peptides that were detected (yellow). Peptides encoded by exon 15 and intron 15 were detected in SNU-251-RR cells and are shown below. g MDA-MB-231 (231), SNU-251 parental (P), SNU-251-RR (RR), MDA-MB-436 (436), HCC1937 (1937) cells were assessed for BRCA1 mRNA expression by RT-PCR with the indicated forward and reverse primer locations. h BRCA1 intron 15 and exons 18–19 specific mRNA expression was examined by quantitative (q)RT-PCR. ***p < 0.001 compared to SNU-251 parental cells. Data are the mean ± standard deviation (SD) of n = 3 biological replicates. Statistical significance was assessed by unpaired, two-tailed t tests.