Diagnostic relevance of overexpressed Nanog gene in early lung cancers.

Currently, no target molecules have been identified that enable the diagnosis of lung cancer with high sensitivity and specificity, especially in the early clinical stages of cancer. Recently, Nanog has been reported to play an important role in the self-renewal and regeneration of ES cells by maintaining these cells in the undifferentiated state and by accelerating cell proliferation. Here, we compared the degree of Nanog mRNA expression in lung cancer tissues with that in non-cancerous tissues. Nanog mRNA was detected in 84.8% (39/46) of lung cancer tissues. The sensitivity and specificity of this diagnostic technique was 80.4 and 93.3%, respectively, as estimated using the cut-off obtained from the analysis of the receiver operating characteristic curve. Further, comparison of paired cancerous and non-cancerous tissues from the same patient revealed elevated Nanog mRNA levels in all patients. No obvious correlations were detected between the clinicopathological factors and Nanog mRNA expression; however, Nanog mRNA was expressed at high levels even in the early clinical stages of the cancer. In addition, the transduction of Nanog siRNA in lung carcinoma cells resulted in growth inhibition. These results suggest that Nanog mRNA might be a new tool to support the diagnosis of lung cancers, irrespective of the clinical stage.