Expression patterns and prognostic value of Bag-1 and Bcl-2 in breast cancer

Yasmine Nadler¹ , Robert L Camp² , Jennifer M Giltnane² , Christopher Moeder² , David L Rimm² , Harriet M Kluger¹ and Yuval Kluger³

¹Department of Medicine, Yale University School of Medicine, New Haven, CT 06520, USA

²Department of Pathology, Yale University School of Medicine, New Haven, CT 06520, USA

³Department of Cell Biology, New York University School of Medicine, 540 First Avenue, 3rd Floor, New York, NY 10016, USA

author email corresponding author email

Breast Cancer Research 2008, 10:R35doi:10.1186/bcr1998


Published:	23 April 2008

Abstract

Introduction

Bcl-2 antanogene-1 (Bag-1) binds the anti-apoptotic mediator Bcl-2, and enhances its activity. Bcl-2 and Bag-1 are associated with chemotherapy resistance in cancer cells. Drugs that target Bcl-2 are currently in clinical development. The purpose of the present study was to examine expression patterns of Bag-1 in a large cohort of breast tumors and to assess the association with Bcl-2, estrogen receptor, progesterone receptor and Her2/neu, and other clinical/pathological variables.

Methods

Tissue microarrays containing primary specimens from 638 patients with 10-year follow-up were employed, and the expression of Bag-1, Bcl-2, estrogen receptor, progesterone receptor and Her2/neu was assessed using our automated quantitative analysis method. We used cytokeratin to define pixels as breast cancer (tumor mask) within the array spot, and we measured biomarker expression within the mask using Cy5 conjugated antibodies.

Results

High Bcl-2 expression was associated with improved survival in the entire cohort and in the node-positive subset (P = 0.008 and P = 0.002, respectively). High Bag-1 expression was associated with improved survival in the node-positive subset (P = 0.006). On multivariable analysis, neither Bcl-2 nor Bag-1 retained their independence as prognostic markers. Strong associations were found between Bag-1, Bcl-2, estrogen receptor and progesterone receptor.

Conclusion

Bag-1 and Bcl-2 expression in breast tumors is associated with improved outcome and steroid receptor positivity. Evaluation of Bcl-2 and Bag-1 expression in breast cancer may identify a subset of patients with a favorable prognosis, who might not benefit from chemotherapy or who might benefit from Bcl-2 targeting agents in addition to antihormonal therapy.