The aim of this study was to determine whether different histologic subtypes of lung adenocarcinoma have distinct microRNA (miR) expression profiles and to identify miRs associated with aggressive subgroups of surgically-resected lung adenocarcinoma (AC). We profiled the miR expression of 91 surgically-resected lung adenocarcinomas and 10 matched nonmalignant lung tissues using TaqMan OpenArray Human microRNA panel. The top 3 prognostic miRs (miR-411, miR-370 and miR-376a) were validated by quantitative PCR in an independent cohort of 60 lung AC. To determine potential underlying biological processes associated with selected miRs, we used Affymetrix U133A gene expression microarray data from 51 miR profiled lung AC tumors. Two lung AC cells (SK-LU-1 and NCI-H2228) overexpressing miR-411 were transfected with miRCURY LNA microRNA power inhibitors for miR-411 or non-target using Lipofectamine RNAimax and plated into Boyden chambers for assessing cell migration. No significant differences in clinical characteristics were observed among the training (n=91) and the test set (n=60). Patients' characteristics: 45% male; 86% smokers; 52% stage I, 25% stage II, 19% stage III and 3% stage IV; 26% adjuvant treatment. Unsupervised hierarchical clustering of 356 expressed miRs identified 3 major clusters of lung AC that correlated with stage (P = 0.023), tumor differentiation (P < 0.003) and histological type of lung AC based on IASLC-based classification (P < 0.005). Cluster 1 was enriched in lepidic and mucinous invasive AC while cluster 3 included the most solid AC. Patients classified in cluster 3 had a shorter median overall survival (16.8 months) as compared to the other clusters (60 months for cluster 1 and 2, Log-rank P = 0.002). We identified 22 miRs significantly overexpressed in cluster 3 and associated with poor survival. Strikingly, 11 out of 22 were structurally associated by their genomic location on the long arm of chromosome 14 (14q32). The top prognostic miRs encoded at 14q32.2 (miR-370) and 14q32.31 (miR-411 and miR-376a) were validated by qPCR in an independent cohort of 60 lung AC. In the multivariate analysis, higher levels of these 3 miRs had significantly worse overall survival (HR = 3.12, 95% CI 1.32 - 7.34, P = 0.009) after adjusting by age, gender and stage. Gene Ontology enrichment analysis based on genes significantly correlated with miR-411, miR-370 and miR-376a expression revealed an association with cell migration and cell adhesion. MiR-411 knockdown significantly reduced cell migration (P < 0.05) in 2 lung AC cells. This study demonstrated that different histological types of lung AC have distinct miRNA expression profiles. We identified and validated 3 prognostic miRNAs (miR-411, miR-370 and miR-376a) which are encoded at 14q32. These miRNAs associated with aggressive subtypes of lung adenocarcinoma may have potential to be actionable targets in the future.

Citation Format: Ernest Nadal, Jules Lin, Rishindra M. Reddy, Nithya Ramnath, Mark B. Orringer, Andrew C. Chang, David G. Beer, Guoan Chen. MicroRNAs encoded at the 14q32 cluster are associated with poor outcome in lung adenocarcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1494. doi:10.1158/1538-7445.AM2014-1494