Expression of DNA double-strand break repair proteins ATM and BRCA1 predicts survival in colorectal cancer.
OBJECTIVE
The double-strand break (DSB) is the major DNA lesion leading to chromosomal aberrations and faithful repair is crucial for maintaining genomic instability. Very little is known about the expression of DNA DSB repair proteins in colorectal cancer. To address this issue, we examined the expression pattern of DSB repair key proteins ATM, BRCA1, BRCA2, Ku70, and Ku80 and their putative role in patients survival in a large series of colorectal cancer.


METHODS
342 sporadic colorectal cancer were subjected to immunohistochemistry by using specific antibodies for the various proteins investigated. Staining results were compared with clinicopathologic data, patient survival, as well as expression of mismatch repair proteins MLH1 and MSH2.


RESULTS
The expression pattern of both ATM and BRCA1 predicted survival in all colorectal cancer patients as well as in the small subgroup of patients that received adjuvant therapy. Low expression of ATM and BRCA1 was associated with loss of MLH1 or MSH2 expression.


CONCLUSIONS
This is the first study to show a relationship between the expression of DNA DSB repair proteins ATM and BRCA1 and survival in colorectal cancer patients. Studies in tumors from large randomized trials are now necessary to validate our pilot data and establish the clinical usefulness of the immunohistochemical assay in predicting response to a particular adjuvant therapy regimen. Furthermore, our results indicate a possible link between expression of DNA mismatch repair and DNA DSB repair proteins in sporadic colorectal cancer, which warrants further investigation.
Academic Unit of Pathology, University of Leeds, UK.
Heike
H
Grabsch
Mit
M
Dattani
Lisa
L
Barker
Nicola
N
Maughan
Karen
K
Maude
Olaf
O
Hansen
Helmut E
HE
Gabbert
Phil
P
Quirke
Wolfram
W
Mueller
D048868:Adaptor Proteins, Signal Transducing; D000230:Adenocarcinoma / Q000378:metabolism / Q000401:mortality / Q000556:secondary; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D034961:Antigens, Nuclear / Q000378:metabolism; D001260:Ataxia Telangiectasia / Q000378:metabolism; D064007:Ataxia Telangiectasia Mutated Proteins; D019313:BRCA1 Protein / Q000378:metabolism*; D024682:BRCA2 Protein / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism*; D049109:Cell Proliferation; D017024:Chemotherapy, Adjuvant; D003106:Colon / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000378:metabolism / Q000401:mortality / Q000473:pathology; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D000072200:Ku Autoantigen; D008297:Male; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein / Q000378:metabolism; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D009687:Nuclear Proteins / Q000378:metabolism; D010865:Pilot Projects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D015996:Survival Rate; D025521:Tumor Suppressor Proteins / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D034961:Antigens, Nuclear; D019313:BRCA1 Protein; D024682:BRCA2 Protein; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen