Research article
Correlation of expression of BP1, a homeobox gene, with estrogen receptor status in breast cancer
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* Corresponding author: Patricia E Berg bcmpeb@gwumc.edu
1 Department of Biochemistry and Molecular Biology, The George Washington University Medical Center, Washington, DC, USA
2 Department of Pathology, The George Washington University Medical Center, Washington, DC, USA
3 Department of Medicine, The George Washington University Medical Center, Washington, DC, USA
4 Greenebaum Cancer Center, University of Maryland Medical School, Baltimore, Maryland, USA
5 Department of Epidemiology and Biostatistics, The George Washington University Medical Center, Washington, DC, USA
6 Department of Biochemistry and Molecular Biology, Howard University College of Medicine, Washington, DC, USA
7 Research Center for Genetic Medicine, Children's National Medical Center, Washington, DC, USA
Breast Cancer Res 2003, 5:R82-R87 doi:10.1186/bcr602
Published: 22 April 2003Abstract
Background
BP1 is a novel homeobox gene cloned in our laboratory. Our previous studies in leukemia demonstrated that BP1 has oncogenic properties, including as a modulator of cell survival. Here BP1 expression was examined in breast cancer, and the relationship between BP1 expression and clinicopathological data was determined.
Methods
Total RNA was isolated from cell lines, tumors, and matched normal adjacent tissue or tissue from autopsy. Reverse transcription polymerase chain reaction was performed to evaluate BP1 expression. Statistical analysis was accomplished with SAS.
Results
Analysis of 46 invasive ductal breast tumors demonstrated BP1 expression in 80% of them, compared with a lack of expression in six normal breast tissues and low-level expression in one normal breast tissue. Remarkably, 100% of tumors that were negative for the estrogen receptor (ER) were BP1-positive, whereas 73% of ER-positive tumors expressed BP1 (P = 0.03). BP1 expression was also associated with race: 89% of the tumors of African American women were BP1-positive, whereas 57% of those from Caucasian women expressed BP1 (P = 0.04). However, there was no significant difference in BP1 expression between grades I, II, and III tumors. Interestingly, BP1 mRNA expression was correlated with the ability of malignant cell lines to cause breast cancer in mice.
Conclusion
Because BP1 is expressed abnormally in breast tumors, it could provide a useful target for therapy, particularly in patients with ER-negative tumors. The frequent expression of BP1 in all tumor grades suggests that activation of BP1 is an early event.