Involvement of dual‐strand of the miR‐144 duplex and their targets in the pathogenesis of lung squamous cell carcinoma

The prognosis of patients with advanced‐stage lung squamous cell carcinoma (LUSQ) is poor, and effective treatment protocols are limited. Our continuous analyses of antitumor microRNAs (miRNAs) and their oncogenic targets have revealed novel oncogenic pathways in LUSQ. Analyses of our original miRNA expression signatures indicated that both strands of miR‐144 (miR‐144‐5p, the passenger strand; miR‐144‐3p, the guide strand) showed decreased expression in cancer tissues. Additionally, low expression of miR‐144‐5p significantly predicted a poor prognosis in patients with LUSQ by The Cancer Genome Atlas database analyses (overall survival, P = 0.026; disease‐free survival, P = 0.023). Functional assays revealed that ectopic expression of miR‐144‐5p and miR‐144‐3p significantly blocked the malignant abilities of LUSQ cells, eg, cancer cell proliferation, migration, and invasion. In LUSQ cells, 13 and 15 genes were identified as possible oncogenic targets that might be regulated by miR‐144‐5p and miR‐144‐3p, respectively. Among these targets, we identified 3 genes (SLC44A5, MARCKS, and NCS1) that might be regulated by both strands of miR‐144. Interestingly, high expression of NCS1 predicted a significantly poorer prognosis in patients with LUSQ (overall survival, P = 0.013; disease‐free survival, P = 0.048). By multivariate analysis, NCS1 expression was found to be an independent prognostic factor for patients with LUSQ patients. Overexpression of NCS1 was detected in LUSQ clinical specimens, and its aberrant expression enhanced malignant transformation of LUSQ cells. Our approach, involving identification of antitumor miRNAs and their targets, will contribute to improving our understanding of the molecular pathogenesis of LUSQ.