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Biological and clinical significance of PARP1 protein expression in breast cancer

Green, Andrew R.; Caracappa, Daniela; Benhasouna, Ahmed A.; Alshareeda, Alaa; Nolan, Christopher C.; Macmillan, R. Douglas; Madhusudan, Srinivasan; Ellis, Ian O.; Rakha, Emad A.

Biological and clinical significance of PARP1 protein expression in breast cancer Thumbnail


Daniela Caracappa

Ahmed A. Benhasouna

Alaa Alshareeda

Christopher C. Nolan

R. Douglas Macmillan

Professor of Breast Cancer Pathology


Poly(ADP-ribose) polymerase-1 (PARP1) is a key facilitator of DNA repair. PARP inhibitors have gained recent attention as promising therapeutic agents for the treatment of solid tumours including breast cancer (BC). However, the biological and clinical significance of PARP1 expression in BC and its role in DNA-damage response (DDR) remain to be defined. We investigated the expression of PARP1 expression, cleaved (PARP1c) and non-cleaved (PAR1nc) forms, in a large and well-characterised cohort of clinically annotated stage I–III operable BCs (n = 1,269) and 43 BRCA1-mutated BCs using immunohistochemistry. PARP1 expression was correlated to clinicopathological variables, outcome and expression of other key DNA repair proteins (BRCA1, RAD51, Ku70/80, PIASγ and CHK1). Expression of PARP1 was exclusively nuclear. 49 and 85 % of sporadic BC showed expression PARP1nc and PARP1c, respectively. In BRCA1-mutated tumours, PARP1nc/PARP1c was highly expressed (95 and 79 %, respectively). PARP1nc expression was positively associated with premenopausal younger age patients, larger size and higher tumour grade. PARP1 was positively associated with DDR-proteins; RAD51, BRCA1, CHK1 and PIASγ (p < 0.001). Negative association was found between PARP1nc and Ki67. PARP1c was associated with ER (p < 0.001). Different associations between PARP1 and DDR-proteins were observed when stratified based on ER/BRCA1 status. PARP1 was not an independent predictor of outcome in sporadic or BRCA1-mutated BC. Our results demonstrate a potential biological role for PARP1c and PARP1nc in DNA repair in BC based on the significant association with other key DNA damage repair proteins. These associations were not restricted to ER-negative or triple-negative subgroup.


Green, A. R., Caracappa, D., Benhasouna, A. A., Alshareeda, A., Nolan, C. C., Macmillan, R. D., …Rakha, E. A. (2015). Biological and clinical significance of PARP1 protein expression in breast cancer. Breast Cancer Research and Treatment, 149(2), 353-362.

Journal Article Type Article
Acceptance Date Dec 2, 2014
Online Publication Date Dec 21, 2014
Publication Date 2015-01
Deposit Date Oct 17, 2018
Publicly Available Date Oct 17, 2018
Journal Breast Cancer Research and Treatment
Print ISSN 0167-6806
Electronic ISSN 1573-7217
Publisher Springer Verlag
Peer Reviewed Peer Reviewed
Volume 149
Issue 2
Pages 353-362
Keywords Cancer Research; Oncology
Public URL
Publisher URL
Contract Date Oct 17, 2018