Expression of phosphorylated MEK2 (Thr394) in colorectal cancer and its clinical implication

AIM:To analyze the phosphorylation of Thr394 residue of mitogen extracellular kinase 2 (MEK2) protein in human colorectal tissues and its clinical significance. METHODS:Formalin-fixed, paraffin-embedded human colorectal tissue specimens were immunostained with the antibody against p-MEK2 (Thr394). The expression levels of p-MEK2 in normal mucosa (n=24), adenoma (n=24) and adenocarcinoma (n=96) of colorectum were compared. Another group of colorectal adenocarcinoma samples (n=417) was used to analyze the expression of p-MEK2 (Thr394) and its relationship with clinicopathological parameters and overall survival. RESULTS:The expression level of p-MEK2 (Thr394) in normal mucosa was 100%, in colorectal adenomas was 66.7% and in colorectal adenocarcinoma was 198%, showing the tendency of decrement and statistically significant differences. No significant correlation between the expression level of p-MEK2 (Thr394) and the clinicopathological parameters including sex, age, body mass index, differentiation degree, T stage, N stage, TNM stage, hepatic metastasis and mutation of K-ras was observed. Moreover, Kaplan-Meier analysis showed that the expression level of p-MEK2 (Thr394) and the prognosis of colorectal cancer had no significant correlation. CONCLUSION: Reduction of p-MEK2 (Thr394) expression occurs during colorectal tumorigenesis. The phosphorylation of Thr394 residue in MEK2 may play an important role in the development of colorectal cancer.