Mir-218-2 Promotes Gliomas Growth, Metastasis And Drug Resistance By Targeting CDC27

Objective: Gliomas has posed a growing challenge for public health problem to elucidate its underlying molecular mechanisms. MicroRNAs (miRNAs) are endogenous, small non-coding RNAs molecules of approximately 20-23 nucleotides. After transcription, cleavage and biologically modification with the help of series of RNA polymerases,the single strand RNA is incorporated into the RNA-induced silencing complex (RISC), the cytoplasmic effector machine for miRNA. With the complementary binding to the target miRNA within RISC at the mRNA 3' untranslated region, the post-transcriptional RNA silencing induces mRNA cleavage, translational inhibition, or mRNA decay. Recent study has proved Mir-218 as an anti-oncogene. Mir-218 is the intronic miRNA encoded by two different slit genes, thus Mir-218-1 and Mir-218-2 are located within an intron of slit2 and slit3 respectively. Mir-218 has been reported highly downregulated in some tumor tissues and participate in several tumor progression pathologies. Nevertheless, the expression between Mir-218-1 and Mir-218-2 as well as their functional significances in gliomas remain largely unknown,nevertheless the specific function of Mir-218-1 and Mir-218-2 has not yet been illustrated. In this passage, we detective the expression and funtion of Mir-218-1 and Mir-218-2 in gliomas. These findings have thrown new light on the potential application of Mir-218-2 in glioma treatment.Methods: Quantitive PCR was used to measure the expression of Mir - 218-1 and Mir - 218-2 in glioma tissues and cell lines. Cell lines that express or knockout Mir-218-2 stablely were built with virus infection. Fluorescence observation and quantitative PCR were used for detection the infectious rates. Transwell Chambers, scratches essay were used to detect the cell migration and invasion ability. F-actin staining was to observe cytoskeleton. CCK-8 cell proliferation curve, the current detection of cell cycle and soft AGAR gel experiment were to observe the proliferation of cells. CCK 8 cells toxicity test and flow measurement of ROS were used to test the drug sensitivity. Western Blotting and Rescue experiments flinally verified the molecular changes of downstream pathway.Results: Mir-218-2 was highly overexpressed in gliomas while Mir-218-1 was downregulated. Further study showed that Mir-218-2 was positively correlated with the growth, metastasis and drug resistance in gliomas. Inhibition of Mir-218-2 suppressed glioma cell proliferation, invasion and migration in vitro as well as tumor growth in vivo. Nevertheless, the overexpression of Mir-218-2 had an opposite effect conversely. In addition, upregulation of Mir-218-2 increased drug resistance of glioma cells to P-lapachone,a selective DNA topoisomerase I inhibitor in cancer therapy. Cell division cycle 27(CDC27), as the downstream target of Mir-218-2, is involved in the regulation of glioma cell behaviors.Overexpression of CDC27 counteracted the function of Mir-218-2 in glioma cells.Conclusions: Mir-218-1 was low expressed in gliomas while Mir-218-2 was highly expressed. Mir-218-2 promoted glioma cells migration, invasion and proliferation. Overexpression of Mir-218-2 decreased the sensitivity to ?-lap in glioma cells. CDC27 was the downstream target of Mir-218-2.