microRNA-338-3p functions as a tumor suppressor in human non‑small‑cell lung carcinoma and targets Ras-related protein 14.

microRNAs (miRNAs) have been demonstrated to be important gene regulators with critical roles in diverse biological processes, including tumorigenesis. Accumulating evidence suggests that miR‑338-3p exerts a tumor suppressor role and is downregulated in tumors, including gastric cancer and colorectal carcinoma. However, the role of miR‑338-3p in lung cancer, particularly non‑small‑cell lung carcinoma (NSCLC), has remained elusive. In the present study, the expression levels of miR‑338-3p in NSCLC tissues were compared with those of matched normal tissues by use of polymerase chain reaction analysis. miR-338-3p was shown to be downregulated in NSCLC tissues, and the expression levels of miR‑338‑3p were significantly correlated with NSCLC cancer differentiation, pathological stage and lymph‑node metastasis. Ectopic miR-338-3p expression significantly suppressed the in vitro proliferation and colony formation of NSCLC cells and enhanced apoptosis. Of note, ectopic miR‑338-3p expression significantly inhibited Ras‑related protein 14 (RAB14) mRNA and protein expression, and reduced luciferase reporter activity containing the RAB14 3'-untranslated region through the first binding site. These findings suggested that miR‑338-3p regulated the survival of NSCLC cells partially through the downregulation of RAB14. Therefore, targeting the miR‑338-3p/RAB14 interaction may serve as a novel therapeutic application to treat NSCLC patients.