Objective: To investigate the MEK and ERK expression and their relationship with clinicopathological parameters in human breast carcinoma, and the effect of preoperative chemotherapy on MEK and ERK protein expression.
Methods: Samples were obtained from 56 patients with breast carcinoma and 8 patients with benign tumors. Sixteen of the 56 patients received preoperative chemotherapy. Western blot and immunohistochemistry were used to measure the expression of MEK1, MEK2 and ERK1, ERK2 protein.
Results: MEK2 and ERK1, ERK2 protein levels were increased in breast carcinoma tissue compared with those in adjacent normal tissues (t = 7.244, 5.959, 3.735, P < 0.01) and benign tumors (t = 2.206, P < 0.05). The levels of MEK1 were decreased. The expression of MEK2 protein in ER negative patients was higher than that in ER positive ones. MEK2 protein levels were lower in patients who received preoperative chemotherapy than in those who did not.
Conclusion: Overexpression of MEK-ERK may play an important role in the development of human breast carcinoma. MEK and ERK protein expressions are inhibited by preoperative chemotherapy.