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Open Access Research article

High nuclear expression levels of histone-modifying enzymes LSD1, HDAC2 and SIRT1 in tumor cells correlate with decreased survival and increased relapse in breast cancer patients

Remco S Derr1, Anneke Q van Hoesel1, Anne Benard1, Inès J Goossens-Beumer1, Anita Sajet1, N Geeske Dekker-Ensink1, Esther M de Kruijf1, Esther Bastiaannet1, Vincent THBM Smit2, Cornelis JH van de Velde1 and Peter JK Kuppen1*

Author Affiliations

1 Department of Surgery, K6-R, Leiden University Medical Center (LUMC), P.O. Box 9600, 2300 RC Leiden, The Netherlands

2 Department of Pathology, LUMC, Leiden, The Netherlands

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BMC Cancer 2014, 14:604  doi:10.1186/1471-2407-14-604

Published: 20 August 2014

Abstract

Background

Breast cancer is a heterogeneous disease with a highly variable clinical outcome in which both genetic and epigenetic changes have critical roles. We investigated tumor expression levels of histone-modifying enzymes LSD1, HDAC2 and SIRT1 in relation with patient survival and tumor relapse in a retrospective cohort of 460 breast cancer patients. Additionally, we correlated expression levels with tumor differentiation and tumor cell proliferation.

Methods

Immunohistochemical staining for LSD1, HDAC2 and SIRT1 was performed on tissue microarrays of tumor and corresponding normal formalin-fixed paraffin-embedded tissues from breast cancer patients. Median nuclear expression levels in tumor tissues were used to divide the patients into low and high expression categories. In combined expression analyses, patients were divided into four subgroups: 1, all enzymes below-median; 2, one enzyme above-median; 3, two enzymes above-median; 4, all three enzymes above-median. The Cox proportional hazard model was used for univariate and multivariate survival analyses. The Pearson Chi-square method was used to assess correlation of combined expression levels with tumor cell proliferation and tumor differentiation.

Results

Expression of LSD1 and SIRT1, but not of HDAC2, was significantly increased in tumor tissues compared to their normal counterparts (both p < 0.001). Multivariate survival analyses identified SIRT1 as independent prognostic factor for relapse-free survival (RFS) with a hazard ratio (HR) of 1.34 (95% CI = 1.04-1.74, p = 0.02). For overall survival (OS), no significant differences were found when the individual enzymes were analyzed. Analyses of combined expression levels of the three histone-modifying enzymes correlated with OS (p = 0.03) and RFS (p = 0.006) with a HR of respectively 1.49 (95% CI = 1.07-2.08) and 1.68 (95% CI = 1.16-2.44) in multivariate analyses and were also related to tumor differentiation (p < 0.001) and tumor cell proliferation (p = 0.002).

Conclusions

When the combined expression levels were analyzed, high expression of LSD1, HDAC2 and SIRT1 showed shorter patient survival time and shorter time to tumor relapse and correlated with poor tumor differentiation and a high level of tumor cell proliferation. Expression of these histone-modifying enzymes might therefore be involved in breast cancer pathogenesis.

Keywords:
Biomarkers; Breast cancer; Clinical outcome; Epigenetics; HDAC2; Histone-modifying enzymes; LSD1; SIRT1