Partial Reduction in BRCA1 Gene Dose Modulates DNA Replication Stress Level and Thereby Contributes to Sensitivity or Resistance

TY - JOUR

T1 - Partial Reduction in BRCA1 Gene Dose Modulates DNA Replication Stress Level and Thereby Contributes to Sensitivity or Resistance

AU - Classen, Sandra

AU - Rahlf, Elena

AU - Jungwirth, Johannes

AU - Albers, Nina

AU - Hebestreit, Luca Philipp

AU - Zielinski, Alexandra

AU - Poole, Lena

AU - Groth, Marco

AU - Koch, Philipp

AU - Liehr, Thomas

AU - Kankel, Stefanie

AU - Cordes, Nils

AU - Petersen, Cordula

AU - Rothkamm, Kai

AU - Pospiech, Helmut

AU - Borgmann, Kerstin

N1 - E Rahlf, N Albers und LP Hebestreit bitte als interne Autoren mit Affiliation "Klinik für Strahlentherapie" eintragen.

PY - 2022/11/1

Y1 - 2022/11/1

N2 - BRCA1 is a well-known breast cancer risk gene, involved in DNA damage repair via homologous recombination (HR) and replication fork protection. Therapy resistance was linked to loss and amplification of the BRCA1 gene causing inferior survival of breast cancer patients. Most studies have focused on the analysis of complete loss or mutations in functional domains of BRCA1. How mutations in non-functional domains contribute to resistance mechanisms remains elusive and was the focus of this study. Therefore, clones of the breast cancer cell line MCF7 with indels in BRCA1 exon 9 and 14 were generated using CRISPR/Cas9. Clones with successful introduced BRCA1 mutations were evaluated regarding their capacity to perform HR, how they handle DNA replication stress (RS), and the consequences on the sensitivity to MMC, PARP1 inhibition, and ionizing radiation. Unexpectedly, BRCA1 mutations resulted in both increased sensitivity and resistance to exogenous DNA damage, despite a reduction of HR capacity in all clones. Resistance was associated with improved DNA double-strand break repair and reduction in replication stress (RS). Lower RS was accompanied by increased activation and interaction of proteins essential for the S phase-specific DNA damage response consisting of HR proteins, FANCD2, and CHK1.

AB - BRCA1 is a well-known breast cancer risk gene, involved in DNA damage repair via homologous recombination (HR) and replication fork protection. Therapy resistance was linked to loss and amplification of the BRCA1 gene causing inferior survival of breast cancer patients. Most studies have focused on the analysis of complete loss or mutations in functional domains of BRCA1. How mutations in non-functional domains contribute to resistance mechanisms remains elusive and was the focus of this study. Therefore, clones of the breast cancer cell line MCF7 with indels in BRCA1 exon 9 and 14 were generated using CRISPR/Cas9. Clones with successful introduced BRCA1 mutations were evaluated regarding their capacity to perform HR, how they handle DNA replication stress (RS), and the consequences on the sensitivity to MMC, PARP1 inhibition, and ionizing radiation. Unexpectedly, BRCA1 mutations resulted in both increased sensitivity and resistance to exogenous DNA damage, despite a reduction of HR capacity in all clones. Resistance was associated with improved DNA double-strand break repair and reduction in replication stress (RS). Lower RS was accompanied by increased activation and interaction of proteins essential for the S phase-specific DNA damage response consisting of HR proteins, FANCD2, and CHK1.

KW - Humans

KW - Female

KW - Genes, BRCA1

KW - Cell Line, Tumor

KW - BRCA1 Protein/genetics

KW - Homologous Recombination

KW - DNA Repair/genetics

KW - DNA Replication

KW - DNA Damage

KW - Breast Neoplasms/genetics

U2 - 10.3390/ijms232113363

DO - 10.3390/ijms232113363

M3 - SCORING: Journal article

C2 - 36362151

VL - 23

JO - INT J MOL SCI

JF - INT J MOL SCI

SN - 1661-6596

IS - 21

M1 - 13363

ER -