Fibroadenoma (FA) and phyllodes tumor (PT) are stromal tumors of breast and are histologically similar. There are no established differences in tumorigenesis and oncogene expression among them. Ras homolog enriched in brain (RHEB) plays an important role in cell growth and cell-cycle control, histone deacetylase 1 (HDAC1) is an important factor in breast tumor progression and prognosis, and WEE1 homolog (WEE1) functions as a tumor suppressor. No studies on the expressional differences of these proteins in FA and PT have been reported to date.
The expression of these proteins in FA, PT, and normal breast was compared. We used 102 cases of FA and 25 cases of benign PT.
In epithelial cells, the expression of RHEB, HDAC1, and WEE1 was lowest in PT, higher in FA, and most enhanced in normal breast. In addition, the expression of RHEB and HDAC1 was higher in the stromal cells of PT than in FA and normal breast.
Both epithelial and stromal cells of FA and PT express these proteins, which indicates that epithelial cells play an important role in the development of stromal tumors. In addition, the expressional differences of these proteins may be associated with the tumorigenesis of breast stromal tumors.
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Histone deacetylase 1 (HDAC1) is associated with the expression and function of estrogen receptors and the proliferation of tumor cells, and has been considered a very important factor in breast tumor progression and prognosis. Several studies have reported an association between HDAC1 expression and poorer prognosis in cancers including breast cancer, with a few exceptions. However, because of the dearth of studies on HDAC1 expression in breast cancer, its significance for breast cancer prognosis has not been well defined. Therefore, we examined HDAC1 expression in invasive ductal carcinoma (IDC), the most common breast cancer, and investigated its potential prognostic significance.
We used 203 IDC tissue samples. Immunohistochemical stains for HDAC1 and real-time polymerase chain reaction for HDAC1 mRNA were performed and the results were compared to generally well-established prognostic factors in breast cancer and patient survival rates.
HDAC1 expression was significantly reduced in proportion to higher histologic grade, higher nuclear pleomorphism score, and higher mitotic counts, and with lower estrogen receptor expression. Furthermore, it was significantly associated with the survival rate.
HDAC1 expression is a good prognostic indicator in IDC.
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