Objective: To investigate the expression of extracellular signal-regulated kinase (ERK) and its relationship with clinicopathological characteristics of breast cancer as well as the effect of preoperative chemotherapy on ERK expression.
Methods: Expression of ERK-1 and ERK-2 protein was examined by Western blot in the breast cancer and normal breast (control) tissue of 48 patients, of whom 8 had received preoperative chemotherapy of 5'-deoxy-5-fluorouridine (5'-DFUR), with distribution of ERKs protein detected by immunohistochemical method.
Results: Expression of ERK-1 and ERK-2 protein was increased in tumor specimen as compared with control tissue (P < 0.01). A positive correlation was observed between ERK-1 and ERK-2 (r = 0.457, P < 0.01). Protein level of ERK-1 and ERK-2 was higher in stage III patients than in stage I and stage II patients (P < 0.05). Expression of both ERK-1 and ERK-2 in the carcinoma tissue was decreased in patients who had received preoperative chemotherapy of 5'-DFUR. ERK-1 and ERK-2 proteins were mainly located in the cytoplasm.
Conclusion: The hyperexpression of ERK may play an important role in the initiation and development of human breast cancer. Preoperative chemotherapy of 5'-DFUR is able to partially inhibit ERK expression.