ABSTRACT
The expression of human epidermal growth factor receptor 2 (HER2), serine-threonine kinase (Akt), 4E-binding protein (4EBP1), phophorylated ribosomal protein S6 kinasel (p70S6Kl) and ribosomal protein S6 ( S6) were detected with immunohistochemistry in 48 cases of human breast cancer. Tumors high-expressing HER2 showed higher Akt expression as compared to tumors with negative HER2 (P < 0. 01). Levels of Akt were correlated with the downstream molecules 4EBP1 ( P < 0. 01) and p70S6K ( P < 0. 05 ). 4EBP1 was mainly expressed in poorly differentiated tumors (P <0. 01) and correlated with tumor size ( P < 0. 05) , lymph node metastasis ( P < 0. 01) and locoregional recurrences ( P < 0. 01). Results suggest that 4EBPl may be the main factor in PI-phosphoinositide-3-kinase (PI3K)-Akt-mammalian targot of rapanycin signal transduction pathways, which is associated with grade of malignancy and prognosis of breast cancer.