Upregulated expression of miR-421 is associated with poor prognosis in non-small-cell lung cancer

Yunxia Li,1 Xiaomei Cui,2 Yongdeng Li,3 Tingting Zhang,4 Shuyun Li5 1Department of Clinical Laboratory, Shouguang People’s Hospital, Shandong 262700, China; 2Department of Neurosurgery, Shouguang People’s Hospital, Shandong 262700, China; 3Department of Joint Surgery, Shouguang People’s Hospital, Shandong 262700, China; 4Hemodialysis Room, Shouguang People’s Hospital, Shandong 262700, China; 5Coronary Care Unit, Shouguang People’s Hospital, Shandong 262700, China Background: Non-small-cell lung cancer (NSCLC) represents the most frequent subtype of lung cancer. MicroRNAs (miRNAs) have attracted a lot of attention with regard to their clinical significance and crucial biological functions in various human cancers. This study aimed to investigate the prognostic significance of microRNA-421 (miR-421) and its correlation with tumor progression in NSCLC. Materials and methods: Expression levels of miR-421 in both serum and tissue samples were measured by quantitative real-time polymerase chain reaction (qRT-PCR). The prognostic value of miR-421 was evaluated using Kaplan–Meier survival analysis and Cox regression assay. To explore the functional role of miR-421 during NSCLC progression, cell experiments were carried out. Results: Expression of serum and tissue miR-421 was upregulated in the NSCLC patients compared with the normal controls (all P<0.001), and the expression showed a significant correlation between the serum samples and tissues (R=0.475, P<0.001). The increased miR-421 expression was associated with positive lymph-node metastasis and advanced TNM stage (all P<0.05). Moreover, patients with high miR-421 expression had poor overall survival compared with those with low expression (log-rank P=0.007). The overexpression of miR-421 proved to be an independent prognostic factor for NSCLC (HR=1.991, 95% CI=1.046–3.791, P=0.036). According to the cell experiments, the proliferation, migration and invasion of NSCLC cells were suppressed by knockdown of miR-421. Conclusion: Overexpression of miR-421 serves as a prognostic biomarker and may be involved in the promotion of tumor progression in NSCLC. Keywords: miR-421, prognosis, progression, non-small-cell lung cance