Reduced ligation during DNA base excision repair supported by BRCA2 mutant cells

Abstract

The brest cancer predisposing genes BRCA1 and BRCA2 appear to be involved in DNA repair. In particular, the sensitivity of BRCA2-de®cient mouse embryonic ®broblasts to ionizing radiation and the demonstrated interaction of the BRCA2 protein with Rad51, a major factor in recombinational repair, indicate that BRCA2 is important for double strand break repair. The human BRCA2-de®cient human cell line Capan-1, whilst being sensitive to ionizing radiation, is also sensitive to the alkylating agent methymethanesulfonate. The major lesions induced by this agent are methylated bases which are removed primarily by the base excision repair (BER) pathway. We have investigated the e ciency of BER in Capan-1 cells by an in vitro assay in which plasmid substrates containing a single lesion are repaired by mammalian cell extracts. In comparison to the control cell lines BxPC-3, T24 and MCF7, Capan-1 cells exhibited a reduced rate of DNA ligation during both the single-nucleotide insertion and PCNA-dependent pathways of BER. The reduced rate of DNA ligation exhibited by Capan-1 cell extracts was complemented by addition of bacteriophage T4 DNA ligase or human DNA ligase III. BRCA2-mutant Capan-1 cells may possess reduced DNA ligase activity during BER.

The Application of Artificial Intelligence to Microarray Data: Identification of a Novel Gene Signature to Identify Bladder Cancer Progression

“…ARHE (also 'Rho family GTPase 3' (RND3)) is a Rho signal transduction member with roles in many cellular processes (cytoskeleton organization, membrane trafficking, cell growth and apoptosis) [29], whose loss is reported in prostate cancer. Deranged DNA repair is represented by BRCA2 and LIG3 [30].Whilst neither is directly linked with bladder carcinogenesis, it is possible that loss of both is required for carcinogenic alteration. BRCA2-deficient cells have reduced DNA ligation capacity which can be reversed by LIG3 administration [30].…”

“…Deranged DNA repair is represented by BRCA2 and LIG3 [30].Whilst neither is directly linked with bladder carcinogenesis, it is possible that loss of both is required for carcinogenic alteration. BRCA2-deficient cells have reduced DNA ligation capacity which can be reversed by LIG3 administration [30].…”

BRCA2 Regulates Homologous Recombination in Response to DNA Damage: Implications for Genome Stability and Carcinogenesis

“…However, in the absence of DSBs, BRCA1/2 may regulate homologous recombination at stalled replication forks to allow DNA damage repair by other simple error-free mechanisms, including mismatch repair, nucleotide excision repair (NER), base excision repair (BER), or replication fork regression. BRCA1/2-deficient cells exhibit reduced DNA ligase activity during BER and a defect in NER (37,43). Brca2 has been shown to stabilize replication forks; in its absence, the forks collapse into DSBs after being stalled at SSBs by hydroxyurea treatment (32).…”

p53 mutated in the transactivation domain retains regulatory functions in homology-directed double-strand break repair

“…In yeast, base excision repair and recombination show overlapping specificities for the removal of certain types of DNA damage, as indicated by the hyper-recombinogenic phenotype after the disruption of base-excision repair genes (Doetsch et al, 2001). Vice versa, cells without the DSB repair factor BRCA2 perform baseexcision repair at a reduced rate (Bogliolo et al, 2000). Therefore, direct and indirect links between polymerase b and recombination seem to exist and may alternatively explain, why, with extrachromosomal substrates, we observed a minor defect in recombination downregulation by p53 (22,23).…”