Inhibition of miR‑18a‑3p reduces proliferation of mesothelioma cells and sensitizes them to cisplatin

: Malignant pleural mesothelioma is a notorious human malignancy. Despite combination chemotherapy with cisplatin and pemetrexed, the majority of patients with advanced malignant pleural mesothelioma have a poor prognosis. MicroRNAs (miRNAs/miRs) are short non-coding RNAs that regulate various biological processes by binding to the 3'-untranslated region of target gene mRNAs and suppressing their expression. Since abnormal expression patterns of miRNAs are a common feature in human malignancies, a number of them have been researched as potential therapeutic targets. Our previous study demonstrated that microRNA-18a (miR-18a) is upregulated in mesothelioma cell lines compared with in non-neoplastic mesothelial tissues, but its function remains unclear. In the present study, miRNA inhibitor was transfected into mesothelioma cell lines and then analyzed various cellular functions. Mesothelioma cells transfected with the miR-18a inhibitor exhibited lower proliferation and migration rates compared with cells transfected with a negative control inhibitor in proliferation and wound scratch assays, respectively. Additionally, the present study revealed that downregulation of miR-18a increased mesothelioma cell apoptosis. In a chemosensitivity assay, transfection of the miR-18a inhibitor significantly increased the sensitivity of mesothelioma cells to cisplatin but not to pemetrexed. Therefore, miR-18a may be a potential therapeutic target for mesothelioma resistant to cisplatin.