The General Practitioner and the Psychiatrist

Abstract

Background/Aim: Distinguishing between primary and metastatic adenocarcinomas in the lung may sometimes be difficult by conventional histopathological methods. In addition, novel biomarkers are needed for the more accurate subtyping of primary lung carcinomas. Materials and Methods: MicroRNA microarrays were performed on 26 primary lung adenocarcinomas, 3 squamous cell carcinomas, 6 small cell lung cancers (SCLCs), and 2 colorectal cancer metastases in the lung. Results: Forty-four microRNAs differentially expressed between three histological subtypes at p<10⁻⁶ predicted histology with 100% accuracy in 100 randomly drawn datasets. Prominent among differentially expressed genes were miR-375, miR-217 and miR-216a, which were found overexpressed in SCLC compared to lung adenocarcinomas. Lung adenocarcinomas overexpressed miR-29b-1, miR-375, miR-2110, miR-29c-star, 199b-5p, and 146b-3p and underexpressed miR-617, miR-205-star, and miR-1246 compared to squamous cell carcinomas. In primary vs. metastatic lung adenocarcinomas, miR-552 and miR-592 were differentially expressed at p<10⁻⁶; the level of expression of miR-552 in colorectal cancer metastases was 39-times higher and that of miR-592 was six-times higher. Furthermore, microRNA profiles of primary colorectal cancer in our database indicated that these two microRNAs were overexpressed in primary colorectal cancer relative to primary lung adenocarcinomas. Conclusion: MicroRNA profiles predict the histology of primary lung carcinomas, and differentiate between primary lung adenocarcinomas and colorectal cancer metastases.