OBJECTIVEThe 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).

METHODSWe 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.

RESULTSWe 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.

CONCLUSIONThe plasma concentration of OLC1 protein is significantly elevated in NSCLC patients. OLC1 may be as a potential cancer biomarker applied in clinical diagnosis.