Increasing BP1 expression correlates with progression and invasion of male breast and prostate tumors
Department of Gynecologic and Breast Pathology, Armed Forces Institute of Pathology and George Washington University Medical Center, Washington, DC, United States
AIM: BP1 is a member of the homeobox gene superfamily of transcription factors that are essential for early development. Our recent studies, however, had revealed that the BP1 gene was activated in 80% of female breast infiltrating ductal carcinoma (IDC), while was silent in the adjacent normal cells and in a vast majority of normal controls (Fu et al. Breast Cancer Research 5:82-87, 2003). BP1 expression was significantly higher in estrogen receptor (ER) negative than in ER positive tumors, 100% versus 73%, (p = 0.03), and in African American than in Caucasian women, 89% versus 57%, (p = 0.04), suggesting that BP1 expression is subject to the influences of the race and ER status. This study attempts to elucidate the expression profile of BP1 in male breast and prostate tumor cells, which are regulated mainly by androgen, to assess whether the expression of BP1 is also subject to influences of hormone types and sex. METHODS: Sections of male breast (n=20) and prostate (n=16) tumors with simultaneous normal, non-invasive, and invasive components, along with reduction mammoplasties (n=34) were immunostained with a polyclonal antibody to BP1 utilizing the ABC method. The frequency and pattern of BP1 immunostaining among cases and among cell types were semi-quantitatively compared. RESULTS: Almost all (>95%) the cells in reduction mammoplasties were devoid of distinct BP1 immunostaining. Distinct BP1 immunostaining was seen in a subset of epithelial cells in both male breast and prostate tissues. The frequency of BP1 expression and the number of BP1 positive cells in both breast and prostate tumors appeared to be linearly increased with the advance of the tumor stages. In tissues contained simultaneous normal, non-invasive, and invasive components, the invasive cells generally displayed the highest intensity of BP1 staining, followed by the non-invasive tumor cells. These findings are comparable to those seen in female breast tumors (Berg et al. Unpublished data). CONCLUSIONS: These findings suggest that BP1 might be an important bio-molecule that is required by multiple types of tumor cells for activation and/or sustainment of invasion.
Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Nice, France; February 7 - 10, 2004; in poster session 892 (Susceptibility genes).