Serum lemur tyrosine kinase 3 expression in colorectal cancer patients predicts cancer progression and prognosis.

Lemur tyrosine kinase-3 (LMTK3) is a member of the families of serine-threonine-tyrosine kinases, which has been suggested to be a possible target and marker of breast cancer. However, its definitive physiopathological function in colorectal cancer (CRC) is poorly understood at present. The aim of this study was to determine the expression levels of preoperative-soluble LMTK3 (sLMTK3) in patients' blood with CRC and to subsequently evaluate whether or not its level in serum can be used to predict cancer progression and prognosis. The expression levels of sLMTK3 were measured by sandwich enzyme-linked immunosorbent assay in blood specimens from 60 patients with CRC and 53 healthy volunteers. As a result, we found that the mean concentration of sKMTK3 in CRC patients was significantly higher than that in healthy volunteers (P = 0.012). The expression levels of sLMTK3 were significantly correlated with histological subtype, depth of tumor invasion, and tumor-node-metastasis (TNM) classification (P = 0.038, 0.021, and 0.049, respectively), but not with sex, age, tumor location, tumor size, or lymph node metastasis. Additionally, Kaplan-Meier survival curves showed that patients with high levels of sLMTK3 had a poorer overall survival rate when compared with those of patients with low levels of sLMTK3 (P = 0.041). Moreover, multivariate analysis demonstrated that sLMTK3 expression and TNM stage were independent prognostic factors for CRC patients (P = 0.047 and 0.008, respectively). These results suggest that serum LMTK3 could be a valuable biomarker for predicting the progression and prognosis of patients with CRC.