Lung adenocarcinoma microRNA-31 expression levels to predict lymph node metastasis and patient survival.

Abstract

7573 Background: In this study we performed genome-wide microRNA-seqencing (miRNA-seq) in lung adenocacinoma (ADC) patient samples and used bioinformatic analyses to identify novel and annotated microRNAs that are differentially expressed between patients with and patients without lymph node metastasis, as well as examining their potential prognostic value. Methods: Sixty four frozen tissue specimens from lung ADC patients collected between 2003 and 2012 were obtained through the OSUCCC Tissue Procurement Shared Resource, approved by internal review board (IRB). Total RNA samples were processed and loaded on the Applied Biosystems SOLiD 4 sequencing system for data acquisition. 249 patients from the TCGA lung ADC cohort were used for results validation. Human lung ADC cell lines H23 and H1573 were used for in vitro functional assays. Results: We identified several microRNAs that were associated with the presence of lymph node metastasis in primary lung adenocarcinoma tissues using genome-wide miRNA-seq. We confirmed miR-31 to be up-regulated in lung ADC tissues from patients with lymph node metastasis in a separate patient cohort (p=0.009, t-test), and to be expressed higher in ADC tissues than in matched normal adjacent lung tissues (p<0.0001, paired t-test). MiR-31 was then validated as a marker for lymphnode metastasis in an external validation cohort of 233 lung ADC cases of the TCGA that did not have distant metastasis (p=0.031, t-test). In vitro functional assays showed that miR-31 upregulation increases cell migration, invasion, and proliferation. In addition, overexpression of mir-31 increased the expression of markers of epithelial-mesenchymal transition (EMT) and associated with activated ERK1/2 signaling. MiR-31 was a significant predictor of survival in a multivariate Cox regression model even when controlling for tumor stage. In silico analysis showed that low expression of miR-31 was associated with excellent survival for T2N0 patients. Conclusions: In summary, we applied microRNA-seq to study microRNomes in lung ADC tissue samples for the first time and identified a microRNA that could predict the presence of lymph node metastasis and survival outcomes in lung ADC patients.