TY - JOUR
T1 - DNA double strand break repair in human bladder cancer is error prone and involves microhomology-associated end-joining
AU - Bentley, Johanne
AU - Diggle, Christine P.
AU - Harnden, Patricia
AU - Knowles, Margaret A.
AU - Kiltie, Anne E.
N1 - Funding Information:
We would like to acknowledge Jo Robinson and Sei Chung Sak for the bladder tumour tissue collection. Tissue culture of NHU cell lines was performed following advice from Eva Pitt. We would like to thank Professor Stephen West for a critical reading of this manuscript. This work was funded by Cancer Research UK.
PY - 2004
Y1 - 2004
N2 - In human cells DNA double strand breaks (DSBs) can be repaired by the non-homologous end-joining (NHEJ) pathway. In a background of NHEJ deficiency, DSBs with mismatched ends can be joined by an error-prone mechanism involving joining between regions of nucleotide microhomology. The majority of joins formed from a DSB with partially incompatible 3′ overhangs by cell-free extracts from human glioblastoma (MO59K) and urothelial (NHU) cell lines were accurate and produced by the overlap/fill-in of mismatched termini by NHEJ. However, repair of DSBs by extracts using tissue from four high-grade bladder carcinomas resulted in no accurate join formation. Junctions were formed by the non-random deletion of terminal nucleotides and showed a preference for annealing at a microhomology of 8 nt buried within the DNA substrate; this process was not dependent on functional Ku70, DNA-PK or XRCC4. Junctions were repaired in the same manner in M059K extracts in which accurate NHEJ was inactivated by inhibition of Ku70 or DNA-PKcs. These data indicate that bladder tumour extracts are unable to perform accurate NHEJ such that error-prone joining predominates. Therefore, in high-grade tumours mismatched DSBs are repaired by a highly mutagenic, microhomology-mediated, alternative end-joining pathway, a process that may contribute to genomic instability observed in bladder cancer.
AB - In human cells DNA double strand breaks (DSBs) can be repaired by the non-homologous end-joining (NHEJ) pathway. In a background of NHEJ deficiency, DSBs with mismatched ends can be joined by an error-prone mechanism involving joining between regions of nucleotide microhomology. The majority of joins formed from a DSB with partially incompatible 3′ overhangs by cell-free extracts from human glioblastoma (MO59K) and urothelial (NHU) cell lines were accurate and produced by the overlap/fill-in of mismatched termini by NHEJ. However, repair of DSBs by extracts using tissue from four high-grade bladder carcinomas resulted in no accurate join formation. Junctions were formed by the non-random deletion of terminal nucleotides and showed a preference for annealing at a microhomology of 8 nt buried within the DNA substrate; this process was not dependent on functional Ku70, DNA-PK or XRCC4. Junctions were repaired in the same manner in M059K extracts in which accurate NHEJ was inactivated by inhibition of Ku70 or DNA-PKcs. These data indicate that bladder tumour extracts are unable to perform accurate NHEJ such that error-prone joining predominates. Therefore, in high-grade tumours mismatched DSBs are repaired by a highly mutagenic, microhomology-mediated, alternative end-joining pathway, a process that may contribute to genomic instability observed in bladder cancer.
UR - http://www.scopus.com/inward/record.url?scp=5144225797&partnerID=8YFLogxK
U2 - 10.1093/nar/gkh842
DO - 10.1093/nar/gkh842
M3 - Article
C2 - 15466592
AN - SCOPUS:5144225797
VL - 32
SP - 5249
EP - 5259
JO - Nucleic Acids Research
JF - Nucleic Acids Research
SN - 0305-1048
IS - 17
ER -
