Effects Of MiR-155Inhibitor On Biological Characteristics In Human Osteosarcoma Cell Line SOSP-9607

Background:As the most common primary malignant bone tumor in children and adolescents,osteosarcoma(OS), which arises mostly in distal femur, proximal tibia and proximalhumerus, is locally aggressive and tends to produce early metastases. For more than halfosteosarcoma originating around the knee, they harm the function of our body badly.Despite the emergence of a new comprehensive treatment program including limb salvagesurgery combined with chemotherapy in OS, but its five-year survival is still65-70%.During the past20years, no further improvement has been made in OS, and recurrenceand metastases have always been the problems that have not been resolved. Given thecurrent status, we urgently need to find new promising treatments for OS.As a class of non-coding small RNAs with regulatory functions in eukaryotic cells,microRNAs （miRNAs） regulate gene expression at the post-transcriptional level. Dysregulations of miRNAs are reported in various tumors, and are closely related totumor progression. Depending on the role of miRNAs in cancer, they have been artificiallydivided into “oncogene” and “tumor suppressor”. As a member of miRNAs family,miR-155is found over-expression in many tumors, and over-expression of miR-155actsas “oncogene” in the progression of these tumors. When our laboratory cloned miRNAs inOS cell line SOSP-9607, we found the existence of miR-155, which also indicated thepotential effect of miR-155in OS.Objective:To observe the effect of miR-155inhibitor on OS cell line SOSP-9607cellproliferation、invasion、migration、cycle and apoptosis.Methods:1.Experiments are divided into three groups: experimental group、negative controlgroup and blank control group, and experimental group is transfected with miR-155inhibitor to inhibit the functions of miR-155.2.MTT and CCK-8assays are carried out to detect OD values of24,48,72,and96hours, and then to figure out growth curve of three groups.3.Using Transwell assays to observe abilities of invasion and migration of threegroups.4.Using flow cytometry to detect the alterations of cell cycle and apoptosis in threegroups.Results:1.The results of MTT and CCK-8assays showed that there was no significant difference between two control groups in cell proliferation, and relative to control groups,experimental group showed significant decrease in cell proliferation（P<0.01）.2.Transwell results showed that there was no significant difference between twocontrol groups in cell invasion and migration, and relative to control groups, experimentalgroup showed significant decrease in cell invasion and migration（P<0.05）.3.Flow cytometry results indicated that compared with control groups, theexperimental group showed significantly higher percentage of cells in G0/G1phase, whilecell ratios of S and G2phase were significantly lower, and the distributions of cell ratio inthree phases were no significantly different between two control groups.4. Flow cytometry results indicated that compared with negative control group（1.2±0.3）%and blank control group（1.1±0.2）%, the cell apoptosis rate of experimentalgroup（8.5±0.4）%was significantly higher, while there were no significant differencebetween two control groups in cell apoptosis rate.Conclution:After inhibiting the functions of miR-155by transfection of miR-155inhibitor, somesignificant effects are shown in biological characteristics of OS cells including cellproliferation, invasion, migration, cycle and apoptosis.