Abstract: Objective To investigate the expression levels of Kruppel-like factor （KLF） 4 and KLF5 and the relationship between their expressions and clinicopathological characteristics in breast invasive ductal carcinoma.
Methods Thirty cases of surgical removal of breast cancer tissue diagnosed with invasive ductal carcinoma by postoperative paraffin pathology and 10 cases of normal breast tissue adjacent to carcinoma were collected from March 2012 to October 2012 in the Affiliated Hospital of Hebei University. The immunohistochemical staining was performed to detect KLF4 and KLF5 levels in invasive ductal carcinoma or adjacent normal breast tissues. The correlation between their expressions and clinicopathological characteristics were analyzed. Results Immunohistochemical results showed both of KLF4 and KLF5 mainly expressed in the nucleus. The KLF4 expression level in invasive ductal carcinoma was significantly lower than that in adjacent normal breast tissues （6.7％ vs. 70.0％, P＜0.05）. The KLF5 expression level in invasive ductal carcinoma was significantly higher than that in adjacent normal breast tissues （90.0％ vs. 30.0％, P＜0.05）. The positive expression rates of KLF4 and KLF5 were not significantly associated with patients age， menopausal status， histological grade， lymph node metastasis, ER and PR expression levels （P＞0.05）. The KLF5 expression level in breast cancer was correlated with HER2 expression level （P＜0.05）. Moreover， no correlation was found between KLF4 and KLF5 expression in invasive ductal carcinoma（r=-0.356, P=0.053）. Conclusion The KLF4 expression level decreases and KLF5 expression level increases in invasive ductal carcinoma， suggesting their important roles of KLFs in breast cancer.