Plasma LUNX mRNA, a non-invasive specific biomarker for diagnosis and prognostic prediction of non-small cell lung cancer.

Lung cancer is the most common cancer worldwide. However, no specific biomarker has been found in diagnosis and evaluation of therapeutic efficacy for lung cancer. The human lung-specific X protein gene (LUNX) was recently identified with a feature of lung tissue specificity. We applied the fluorescent quantitative polymerase chain reaction method to examine LUNX mRNA in plasma and peripheral blood mononuclear cells (PBMC) in patients with non-small cell lung cancer (NSCLC), benign lung diseases, extrapulmonary tumors, and healthy subjects. The results showed that LUNX mRNA in both of plasma and PBMC were significantly higher in lung cancer patients compared to other groups. In plasma, there were higher sensitivity and negative predictive value of LUNX mRNA than in PBMC. Patients with III~IV stages of lung cancer had more LUNX mRNA in plasma than the early stage of lung cancer sufferers. After a period of therapy, significant reductions of plasma LUNX mRNA in patients with I and II stages of lung cancer were found. Levels of plasma LUNX mRNA in patients who had succeeded to respond to therapy decreased compared to prior treatment. On the other hand, the post-treatment level was obviously increased in patients that had failed to respond to therapy. Patients with negative plasma LUNX mRNA after therapy displayed a favorable prognosis and survival rate. These preliminary data suggested that cell-free LUNX mRNA in plasma as a non-invasive biomarker, is superior to peripheral intracellular LUNX mRNA, and plays a critical role in specific diagnosis and prognostic prediction of non-small cell lung cancer.