Distinct spatial expression patterns of AP-2alpha and AP-2gamma in non-neoplastic human breast and breast cancer

Although transcription factors AP- 2alpha and AP- 2gamma have been implicated in the control of estrogen receptor ( ER) and ErbB- 2, their impact for breast cancer is still controversial. To better understand the role of AP- 2 proteins in mammary neoplasia, the analysis of their spatial expression pattern in normal breast and breast cancer is required. A total of 51 specimens of female breast cancer patients and a tissue microarray containing 93 additional female breast cancer cases were immunohistochemically stained for AP- 2alpha, AP-2gamma, ER and ErbB- 2. In 70 cases of the tissue microarray, survival data comprising a period of up to 30 years were present. In non- neoplastic breast tissue, AP- 2alpha was expressed in the inner glandular cell layer while AP- 2gamma was expressed in the outer myoepithelial cell layer. Ductal carcinoma in situ revealed strongly AP- 2alpha- positive tumor cells surrounded by a layer of AP- 2gamma- positive myoepithelial cells. In invasive carcinoma, expression of AP- 2alpha and AP- 2gamma was variable. High expression of ER and AP-2alpha showed better survival rates than low expression of these markers. AP- 2gamma expression had no effect on survival. These results for the first time reveal a distinct spatial expression pattern of AP- 2alpha and AP- 2gamma in normal breast and in ductal carcinoma in situ with specific AP- 2gamma expression in myoepithelium. High ER and AP- 2alpha expression in invasive breast cancer showed favorable survival rates. Therefore, AP- 2alpha expression seems to be associated with better prognosis of breast cancer. AP- 2gamma expression has no influence on survival reflecting that myoepithelial cells are not involved in the neoplastic process.