Prognostic significance of monocarboxylate transporter 4 expression in patients with colorectal cancer.

Cancer cells generally have a high rate of glycolysis and produce larger quantities of lactate as compared to the surrounding normal cells. Monocarboxylate transporter 4 (MCT4) is one of the proton pumps exchanging the lactate through the plasma membrane. The prognostic significance of MCT4 expression has not been evaluated in patients with colorectal cancer (CRC). Surgical specimens from 105 CRC patients were immunohistochemically stained using a polyclonal anti-MCT4 antibody. The relationships among the MCT4 expression, clinicopathological factors and prognosis were evaluated. A total of 53 (50.5%) of the 105 patients with CRC were determined to have tumors positive for MCT4 expression. The expression of MCT4 significantly correlated with the tumor size, depth of invasion, lymph node metastasis, distant metastasis and TNM staging. The survival rate of the patients who were positive for MCT4 expression was significantly lower than that of patients with negative MCT4 expression. Positive MCT4 expression was a significantly poor prognostic factor, as determined by both univariate and multivariate analyses. Therefore, positive MCT4 expression appears to be a useful marker for tumor progression and prognosis in patients with CRC.