[OLC1 protein levels in plasma of patients with non-small cell lung cancer and its clinical application].

OBJECTIVE: The aim of this study was to detect the plasma concentration of OLC1 (overexpressed in lung cancer 1) protein as a potential cancer biomarker, and evaluating its clinical application value in the diagnosis of non-small cell lung cancer (NSCLC). METHODS: We prepared OLC1 antibody with OLC1 full length protein, in 5-6-week old Bal B/c mice. Each mouse was immunized four times at a dose of 15-30 µg antigen protein, and the interval between two consecutive immunizations was two weeks. Antibody screening was made by ELISA and Western blot, and a double antibody sandwich ELISA kit was developed. We used this established ELISA kit to detect the plasma concentration of OLC1 protein in 281 NSCLC patients and 92 gender- and age-matched healthy controls. Area under the receiver operating characteristic curve (AUC) was used to evaluate the detection efficacy of OLC1. RESULTS: We obtained 11 OLC1 monoclonal antibodies and successfully established the ELISA kit to detect the plasma concentration of OLC1 with a detection range from 1.95 ng/ml to 62.50 ng/ml. OLC1 concentration in the case group (124.69 ng/ml) was significantly higher than that in the control group (67.07 ng/ml, P < 0.001). In the scenario of distinguishing NSCLC from control group, AUC result was 0.69. When the cut-off was set at 67.72 ng/ml, the sensitivity and specificity was 84.4% and 51.1%, respectively. In term of distinguishing early lung cancer (IA) from normal controls, the AUC, sensitivity and specificity were 0.68, 77.8% and 54.4%, respectively. CONCLUSION: The plasma concentration of OLC1 protein is significantly elevated in NSCLC patients. OLC1 may be as a potential cancer biomarker applied in clinical diagnosis.