Background and objectives: Midkine (MK) mRNA was highly expressed in various human cancer tissues and cells. The present study aimed to investigate whether MK mRNA level in peripheral blood mononuclear cells (PBMC) could serve as a diagnostic biomarker for patients having primary non-small cell lung cancer (NSCLC).
Methods: MK mRNA level in PBMC from 87 patients with primary NSCLC, 35 patients with lung benign lesion (LEL), and 30 healthy volunteers was analyzed by real-time quantitative RT-PCR. The levels of serum carcinoembryonic antigen, carbohydrate antigen 125 (CA125), and neuron-specific enolase were detected by chemiluminescent microparticle enzyme immunoassay.
Results: PBMC MK mRNA level was significantly higher in patients with primary NSCLC than that in other groups (P < 0.001), while there was no significant difference between LEL patients and healthy volunteers (P > 0.05). Higher MK mRNA level was correlated with clinical stages (P = 0.026), differentiation (P = 0.025), and lymph node metastasis (P = 0.022) of NSCLC. Using a cutoff of 0.0063, the sensitivity and specificity of MK mRNA levels to differentiate between patients with NSCLC and patients with LEL were 57.47 and 93.33 %,and it were 56.32 and 93.33 % for patients with NSCLC and healthy volunteers, respectively. Furthermore, multivariate analysis indicated that PBMC MK mRNA level above the cutoff value presented a chance of 11-fold higher for NSCLC occurrence.
Conclusions: MK mRNA level in PBMC may be a potential non-invasive molecular marker for the diagnosis of primary NSCLC.