Sputum MicroRNA Profiling: A Novel Approach for the Early Detection of Non-Small Cell Lung Cancer

Purpose: MicroRNAs (miRNAs) post-transcriptionally regulate hundreds of gene targets involved in tumorigenesis thereby controlling vital biological processes, including cellular proliferation, differentiation and apoptosis. MiRNA profiling is an emerging tool for the potential early detection of a variety of malignancies. This study was conducyed to assess the feasibility and methodological robustness of quantifying sputum miRNAs, employing quantitative real-time polymerase chain reaction (RT-qPCR) and cluster analysis on an optimized miRNA profile as a novel approach for the early detection of non-small cell lung cancer (NSCLC). Methods: The relative expressions of 11 miRNAs in sputum (miR-21, miR-145, miR-155, miR-205, miR-210, miR-92, miR-17-5p, miR-143, miR-182, miR-372, and let-7a) in addition to U6 were retrospectively assessed in four NSCLC-positive and four negative controls. Subsequently, a set of five miRNAs (miR-21, miR-143, miR-155, miR-210, miR-372) was selected because of degree of relatedness observed in the cluster analysis and tested in the same sputum sample set. The five optimized miRNAs accurately clustered these eight retrospective patients into NSCLC positive cases and negative controls. The five miRNA panel was then prospectively quantified in the sputum of 30 study patients (24 NSCLC cases and six negative controls) in a double-blind fashion to validate a five miRNA panel using hierarchical cluster analysis. Results: The optimized five miRNA panel detected NSCLC (83.3% sensitivity and 100% specificity) in 30 prospectively accrued study patients. Conclusion: Sputum miRNA profiling using cluster analysis is a promising approach for the early detection of non-small cell lung cancer. Further investigation using this approach is warranted