High-Throughput\nComputer Screen Aids Discovery of\nMethotrexate as miR-20b Inhibitor to Suppress Nonsmall Cell Lung Cancer\nProgression

MicroRNAs (miRNAs) play a significant role in tumor progression,\nand regulating miRNA expression with small molecules may offer a new\napproach to cancer therapy. Among them, miRNA-20b has been found to\nbe dysregulated in several cancers, including nonsmall cell lung cancer\n(NSCLC). Herein, an in silico high-throughput computer screen was\nconducted to identify small molecules that downregulate miR-20b using\nthe three-dimensional structure of the Dicer binding site on pre-miR-20b.\nAmong 1058 small molecule compounds, Methotrexate (MTX), was discovered\nto be a potential miR-20b-specific inhibitor, which has been found\nto suppress miR-20b by specifically blocking Dicer processing in p53\nwild-type A549 NSCLC cells but not in H1299 cells with p53 depletion.\nMTX effectively inhibited the proliferation, survival, migration,\nand invasion of A549 cells in a dose-dependent manner. Furthermore,\nthe treatment of MTX up-regulated the expression of miR-20b target\ngenes PTEN, STAT3, and HIF1α. Notably, MTX also significantly\ninhibited tumor growth in a mouse xenograft tumor model of NSCLC,\nwith no observed tissue toxicity. Our findings indicate that MTX may\nhave a novel role as an established drug in p53 wild-type NSCLC tumor\ntherapy by down-regulating miR-20b expression. These findings are\nexpected to provide preclinical evidence for miR-20b-targeting NSCLC\ntherapeutic strategies.