Integrating DNA methylation and microRNA biomarkers in sputum for lung cancer detection

Abstract

Background: Abnormal microRNA (miRNA) expressions and promoter methylation of genes detected in sputum may provide biomarkers for non-small lung cancer (NSCLC). Here, we evaluate the individual and combined analysis of the two classes of sputum molecular biomarkers for NSCLC detection.

Results: We analyze expression of 3 miRNAs (miR-21, miR-31, and miR-210) and methylation of 3 genes (RASSF1A, PRDM14, and 3OST2), which were previously identified as potential biomarkers for NSCLC, in sputum of a set of 117 stage I NSCLC patients and 174 cancer-free smokers. The results are validated in a different set of 144 stage I NSCLC patients and 171 controls. The panel of 3 miRNA biomarkers has 81.5 % sensitivity and 85.9 % specificity; the panel of 3 methylation biomarkers displays 82.9 % sensitivity and 76.4 % specificity for NSCLC detection. Integrated analysis of 2 miRNAs (miR-31 and miR-210) and 2 genes (RASSF1A and 3OST2) yields higher sensitivity (87.3 %) and specificity (90.3 %) compared with the individual panels of the biomarkers (P < 0.05). Combined analysis of all the 3 miRNAs and 3 genes does not have performance superior to that of the panel of 2 miRNAs and 2 genes (P > 0.05). The performance of combined use of the two classes of biomarkers was confirmed in the validation set.

Conclusions: The integration of two different classes of biomarkers synergistically improves both the sensitivity and the specificity for the early detection of NSCLC.

Keywords: DNA methylation; Diagnosis; Lung cancer; MicroRNA; Sputum.

Fig. 1

Combined analysis of miRNA and DNA methylation biomarkers in sputum has a synergistic effect for lung cancer detection. a ROC curve of a panel of 3 miRNA biomarkers (miR-21, miR-31, and miR-210) shows an AUC of 0.89 for differentiating NSCLC patients from smokers with benign pulmonary nodules in terms of sensitivity and specificity. b A panel of 3 DNA methylation biomarkers (RASSF1A, 3OST2, and PRDM14) creates an AUC of 0.79 for distinguishing NSCLC patients from the cancer-free smokers. c The integration of 2 miRNAs (miR-31 and miR-210) and 2 TSGs (RASSF1A and 3OST2) yields 0.93 AUC, which is statistically higher than that of the panel of 3 miRNA biomarkers and the panel of 3 methylation biomarkers (P < 0.05)