Epigenetic inactivation of microRNA-34b/c predicts poor disease-free survival in early-stage lung adenocarcinoma

A MicroRNA cluster at 14q32 drives aggressive lung adenocarcinoma

PURPOSE

To determine whether different subtypes of lung adenocarcinoma (AC) have distinct microRNA (miRNA) expression profiles, and to identify miRNAs associated with aggressive subgroups of resected lung AC.

EXPERIMENTAL DESIGN

miRNA expression profile analysis was performed in 91 resected lung AC and 10 matched nonmalignant lung tissues using a PCR-based array. An independent cohort of 60 lung ACs was used for validating by quantitative PCR the top 3 prognostic miRNAs. Gene-expression data from 51 miRNA profiled tumors was used for determining transcript-specific miRNA correlations and gene-enrichment pathway analysis.

RESULTS

Unsupervised hierarchical clustering of 356 miRNAs identified 3 major clusters of lung AC correlated with stage (P = 0.023), tumor differentiation (P < 0.003), and IASLC histologic subtype of lung AC (P < 0.005). Patients classified in cluster 3 had worse survival as compared with the other clusters. Eleven of 22 miRNAs associated with poor survival were encoded in a large miRNA cluster at 14q32. The top 3 prognostic 14q32 miRNAs (miR-411, miR-370, and miR-376a) were validated in an independent cohort of 60 lung AC. A significant association with cell migration and cell adhesion was found by integrating gene-expression data with miR-411, miR-370, and miR-376a expression. miR-411 knockdown significantly reduced cell migration in lung AC cell lines and this miRNA was overexpressed in tumors from patients who relapsed systemically.

CONCLUSIONS

Different morphologic subtypes of lung AC have distinct miRNA expression profiles, and 3 miRNAs encoded at 14q32 (miR-411, miR-370, and miR-376a) were associated with poor survival after lung AC resection.