title: BRCA1/2 mutation analysis in 41 ovarian cell lines reveals only one functionally deleterious BRCA1 mutation.
abstract: Mutations in BRCA1/2 increase the risk of developing breast and ovarian cancer. Germline BRCA1/2 mutations occur in 8.6-13.7% of unselected epithelial ovarian cancers, somatic mutations are also frequent. BRCA1/2 mutated or dysfunctional cells may be sensitive to PARP inhibition by synthetic lethality. The aim of this study is to comprehensively characterise the BRCA1/2 status of a large panel of ovarian cancer cell lines available to the research community to assist in biomarker studies of novel drugs and in particular of PARP inhibitors. The BRCA1/2 genes were sequenced in 41 ovarian cell lines, mRNA expression of BRCA1/2 and gene methylation status of BRCA1 was also examined. The cytotoxicity of PARP inhibitors olaparib and veliparib was examined in 20 cell lines. The cell line SNU-251 has a deleterious BRCA1 mutation at 5564G > A, and is the only deleterious BRCA1/2 mutant in the panel. Two cell lines (UPN-251 and PEO1) had deleterious mutations as well as additional reversion mutations that restored the protein functionality. Heterozygous mutations in BRCA1/2 were relatively common, found in 14.6% of cell lines. BRCA1 was methylated in two cell lines (OVCAR8, A1847) and there was a corresponding decrease in gene expression. The BRCA1 methylated cell lines were more sensitive to PARP inhibition than wild-type cells. The SNU-251 deleterious mutant was more sensitive to PARP inhibition, but only in a long-term exposure to correct for its slow growth rate. Cell lines derived from metastatic disease are significantly more resistant to veliparib (2.0 fold p = 0.03) compared to those derived from primary tumours. Resistance to olaparib and veliparib was correlated Pearsons-R 0.5393, p = 0.0311. The incidence of BRCA1/2 deleterious mutations 1/41 cell lines derived from 33 different patients (3.0%) is much lower than the population incidence. The reversion mutations and high frequency of heterozygous mutations suggest that there is a selective pressure against BRCA1/2 in cell culture similar to the selective pressure seen in the clinic after treatment with chemotherapy. PARP inhibitors may be useful in patients with BRCA1 deleterious mutations or gene methylation.
authors: Department of Histopathology, St James' Hospital and Trinity College Dublin, Dublin 8, Ireland. stordalb@tcd.ie
authors: Britta
authors: B
authors: Stordal
authors: Kirsten
authors: K
authors: Timms
authors: Angela
authors: A
authors: Farrelly
authors: Danielle
authors: D
authors: Gallagher
authors: Steven
authors: S
authors: Busschots
authors: Mickaël
authors: M
authors: Renaud
authors: Julien
authors: J
authors: Thery
authors: Deborah
authors: D
authors: Williams
authors: Jennifer
authors: J
authors: Potter
authors: Thanh
authors: T
authors: Tran
authors: Greg
authors: G
authors: Korpanty
authors: Mattia
authors: M
authors: Cremona
authors: Mark
authors: M
authors: Carey
authors: Jie
authors: J
authors: Li
authors: Yang
authors: Y
authors: Li
authors: Ozlem
authors: O
authors: Aslan
authors: John J
authors: JJ
authors: O'Leary
authors: Gordon B
authors: GB
authors: Mills
authors: Bryan T
authors: BT
authors: Hennessy
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D019313:BRCA1 Protein / Q000235:genetics*; D024682:BRCA2 Protein / Q000235:genetics*; D001483:Base Sequence; D045744:Cell Line, Tumor; D019175:DNA Methylation; D004252:DNA Mutational Analysis; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D019656:Loss of Heterozygosity; D009154:Mutation; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D010053:Ovary / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D000067856:Poly(ADP-ribose) Polymerase Inhibitors
chemical_list: D000970:Antineoplastic Agents; D019313:BRCA1 Protein; D024682:BRCA2 Protein; D000067856:Poly(ADP-ribose) Polymerase Inhibitors