miRNA-197 and miRNA-184 are associated with brain metastasis in EGFR-mutant lung cancers

Introduction: The prognostic value of EGFR mutation in lung cancer patients with brain metastases is uncertain and therapeutic efficacy with EGFR TKI is limited. Looking for biomarkers closely related with early tumor changes and brain metastases in non-small cell lung cancer is warranted. MicroRNAs (miRNAs) are frequently deregulated in lung cancer. The objective of this study was to investigate whether some miRNAs are related with brain metastasis risk in EGFR-mutant non-small cell lung cancer patients. Materials and methods: miRNA quantification was retrospectively performed in formalin-fixed, extracranial paraffin-embedded adenocarcinoma tumor tissue available from 17 human samples of advanced non-small cell lung cancer patients. Samples were classified as brain metastasis group (5 EGFR-mutant patients with initial BM, EGFRm-BM+; and 6 EGFR wild-type patients with initial BM) and the control group (6 EGFR-mutant NSCLC patients without BM). The RNA obtained was preamplified and retro-transcribed, and the miRNA was quantified with the TaqMan OpenArray Human MiRNA Panel in the QuantStudio™ 12 K Flex Real-Time PCR system. Results: miRNA-197 and miRNA-184 showed a significant higher expression in EGFRm-BM+ group than in the control group (p = 0.017 and p = 0.01, for miRNA-197 and miRNA-184, respectively), with a trend toward overexpression in BM group compared with the control group (p = 0.08 and p = 0.065, for miRNA-197 and miRNA-184, respectively), without differences in expression in BM group according to EGFR mutational status (EGFR wild type vs. EGFR-mutant: p = 0.175 and p = 0.117, for miRNA-197, miRNA-184 respectively). Conclusions: miRNA-197 and miRNA-184 are overexpressed in EGFR-mutant patients with BM and they might be a new biomarker for stratifying the risk of BM in this subpopulation.