[ABSTRACT]AIM:ToinvestigatetheroleoftinyantisensenucleicacidagainstmiR-155(tinyantimiR-155, t-antimiR-155) in multiple myeloma cells .METHODS:According to the seed sequence of miR-155, t-antimiR-155 was designed and synthesized .t-antimiR-155 was transfected by Lipofectamine TM 2000 into RPMI-8266 cells.The cells were di-vided into t-antimiR-155 group, scrambled control (SCR) group and blank control group .The growth-inhibitory potencies were measured by MTT assay .The ability of cell colony formation was detected by cell colony formation assay .The cell ap-optosis was assessed by flow cytometry with annexin V /PI double staining .RESULTS: The best concentration and time were 0.4 μmol/L and 48 h, respectively.The cell colony forming experiment showed that the circumstances of forming cell community in t-antimiR-155 group was weaker than that in SCR group , and the colony formation inhibitory rate of former was significant higher than the latter .Compared with SCR group , the cell apoptosis in t-antimiR-155 group significantly in-creased.CONCLUSION: The t-antimiR-155 inhibits the progression of multiple myeloma cells by interfering with miR-155.miR-155 may serve as a potential target in gene therapy for treating multiple myeloma .