Correlation of expression of BP1, a homeobox gene, with estrogen receptor status in breast cancer

Abstract

DCIS = ductal carcinoma in situ; ER = estrogen receptor; HB = homeobox; HD = homeodomain; PR = progesterone receptor; RT-PCR = reverse transcription polymerase chain reaction. (Print ISSN 1465-5411; Online ISSN 1465-542X). This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL. Breast Cancer Research Vol 5 No 4 Fu et al. Research article Correlation of expression of BP1, a homeobox gene, with estrogen receptor status in breast cancer AbstractBackground: 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.

BP1, a homeoprotein, is significantly expressed in prostate adenocarcinoma and is concordant with prostatic intraepithelial neoplasia

“…Current and published work suggests a role for BP1 in carcinogenesis and progression. Based on previous work 4,5 and the present results in prostate cancer, it appears that BP1 is involved in the carcinogenic sequence as it appears to be expressed in 46% of ductal carcinomas in situ of the breast and all the examples of PIN identified in prostate cancer sections. Moreover, BP1 appears to be involved in cellular proliferation and in altering or blocking the pathway of programmed cell death (apoptosis).…”

“…This study demonstrates that the frequency and intensity of BP1 expression, as measured by immunohistochemical reactivity, increases within PIN and prostatic carcinoma relative to benign acinar glands and that the extent and intensity of the 4,5 Analogous to breast cancers, BP1 immunoreactivity was not present in normal prostatic tissue, but demonstrated diffuse and strong immunoreactivity within neoplastic cells of PIN and invasive adenocarcinoma.…”

“…3 Our studies in breast cancer have demonstrated that BP1 expression was present in 80% of infiltrating duct carcinomas and relatively absent in matched normal controls. 4,5 We have also shown that BP1 expression was significantly higher in cancers that were estrogen receptor negative relative to estrogen receptor positive breast tumors and in African Americans than in Caucasians. 4 BP1 demonstrates significant expression in breast cancers with a relative aggressive phenotype, namely, estrogen receptor negative and inflammatory breast cancers, and consequently, we may propose several analogies that may be relevant to prostate cancers.…”

“…4,5 We have also shown that BP1 expression was significantly higher in cancers that were estrogen receptor negative relative to estrogen receptor positive breast tumors and in African Americans than in Caucasians. 4 BP1 demonstrates significant expression in breast cancers with a relative aggressive phenotype, namely, estrogen receptor negative and inflammatory breast cancers, and consequently, we may propose several analogies that may be relevant to prostate cancers. Invasive cancers are believed to result from a progressive, multi-step process initiated and driven by a sequential accumulation of genetic and biochemical abnormalities.…”

BP1, a Potential Biomarker for Breast Cancer Prognosis

“…In earlier study in which semiquantitative reverse transcription polymerase chain reaction (RT-PCR) was performed to evaluate BP1 expression, BP1 was active in 80% of invasive ductal breast tumors, where 100% of ER-negative tumors were BP1 positive, compared with 73% of ER-positive tumors (p = 0.03) [33]. BP1 expression may also be associated with race: 89% of the tumors of African-American women expressed BP1 while 57% of Caucasian women showed BP1 positivity (p = 0.04).…”