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Clinicopathological significance of human apurinic/apyrimidinic endonuclease 1 (APE1) expression in oestrogen-receptor-positive breast cancer

Abdel-Fatah, Tarek M. A.; Perry, Christina; Moseley, Paul; Johnson, Kerstie; Arora, Arvind; Chan, Stephen; Ellis, Ian O.; Madhusudan, Srinivasan


Tarek M. A. Abdel-Fatah

Christina Perry

Paul Moseley

Kerstie Johnson

Arvind Arora

Stephen Chan


Oestrogen metabolites can induce oxidative DNA base damage and generate potentially mutagenic apurinic sites (AP sites) in the genomic DNA. If unrepaired, mutagenic AP sites could drive breast cancer pathogenesis and aggressive phenotypes. Human apurinic/apyrimidinic endonuclease 1 (APE1) is a key DNA base excision repair (BER) protein and essential for processing AP sites generated either directly by oestrogen metabolites or during BER of oxidative base damage. Our hypothesis is that altered APE1 expression may be associated with aggressive tumour biology and impact upon clinical outcomes in breast cancer. In the current study, we have investigated APE1 protein expression in a large cohort of breast cancers (n = 1285) and correlated to clinicopathological features and survival outcomes. Low APE1 protein expression was associated with high histological grade (p < 0.000001), high mitotic index (p < 0.000001), glandular de-differentiation (p < 0.000001), pleomorphism (p = 0.003), absence of hormonal receptors (ER?/PgR?/AR?) (p < 0.0001) and presence of triple negative phenotype (p = 0.001). Low APE1 protein expression was associated with loss of BRCA1, low XRCC1, low FEN1, low SMUG1 and low pol ? (ps < 0.0001). High MIB1 (p = 0.048), bcl-2 negativity (p < 0.0001) and low TOP2A (p < 0.0001) were likely in low APE1 tumours. In the ER-positive sub-group, specifically, low APE1 remains significantly associated with high histological grade, high mitotic index, glandular de-differentiation (ps < 0.00001) and poor breast cancer specific survival (p = 0.007). In the ER-positive cohort that received adjuvant endocrine therapy, low APE1 protein expression is associated with poor survival (p = 0.006). In multivariate analysis, low APE1 remains independently associated with poor survival in ER-positive tumours (p = 0.048). We conclude that low APE1 expression may have prognostic and predictive significance in ER-positive breast cancers.


Abdel-Fatah, T. M. A., Perry, C., Moseley, P., Johnson, K., Arora, A., Chan, S., …Madhusudan, S. (2014). Clinicopathological significance of human apurinic/apyrimidinic endonuclease 1 (APE1) expression in oestrogen-receptor-positive breast cancer. Breast Cancer Research and Treatment, 143(3), 411-421.

Journal Article Type Article
Acceptance Date Dec 20, 2013
Online Publication Date Jan 1, 2014
Publication Date Feb 28, 2014
Deposit Date Dec 6, 2018
Journal Breast Cancer Research and Treatment
Print ISSN 0167-6806
Electronic ISSN 1573-7217
Publisher BMC
Peer Reviewed Peer Reviewed
Volume 143
Issue 3
Pages 411-421
Public URL
Publisher URL