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Purpose: To Explore biological functions and preliminary molecular mechanisms of TY04 target multiple myeloma (MM) cell.Methods: MM cell lines were cultured and treated with aptamer TY04.The proliferation of MM cell lines was detected by cell counting kit-8 assay.Flow-cytometry was used to analyze cell cycle,apoptosis and the binding ability of TY04 with MM.1S cell.Binding affinity for MM.lS cells was further studied by flow cytometry after the unselected ssDNA library and TY04 were incubated with MM.1S cells at 4 ℃ and 37 ℃,respectively.The level of CDK1,cyclin B1 and γ-tubulin was measured by mean fluorescence intensity (MFI) using flow cytometry.Result: TY04 inhibited the growth of several MM cell lines.Because the MM.1S cell line was the most sensitive to TY04 among these cell lines,it was selected as a model to further explore the detailed action of TY04 on MM.The result showed that TY04 decreased the survival of MM.1S cells in a dose-dependent manner.The concentration of TY04 needed to inhibit 50% of the growth (IC50) of MM.1S cells was 3.89 μM.The unselected ssDNA library (Lib) did not exhibit the significant inhibitory effect on the growth of MM.1S cells.By using fluorescence microscopy,we found that fluorescence intensity of the cells incubated with TY04 increased compared with the ssDNA library (Lib) and TY04 bound to MM.1S cells with the same efficiency at either 4 or 37 ℃.Binding affinity results measured by flow cytometry showed MM.1S cells incubated with increasing concentrations (0,25,125,and 500 nM,respectively) of TY04,the fluorescence intensity correspondingly increased.Furthermore,by using fluorescence microscopy it was confirmed that TY04 bound to the surface of MM.1S cells at both 4 and 37 ℃.TY04 partly lost its recognition ability when MM.1S cells were briefly treated with trypsin and proteinase K before incubation with TY04,indicating that cell surface membrane proteins must constitute some of the target molecules recognized by TY04.We found that exposure of MM.1S to a growth-suppressive concentration of TY04 (4 μM) for 96 h induced a marked accumulation of cells in G2/M phase and resulted in the accumulation of binucleated cells.In addition,treating MM.1S cells with TY04,we observed an increase in MFI of CDK1 and cyclin B 1,respectively.In addition,TY04 also caused a decrease in the expression of γ-tubulin.Conclusion: The aptamer TY04 bound to MM cells and inhibited the growth via cell cycle arrest in mitosis.Upregulation of CDK 1 and cyclin B 1 expression and downregulation of γ-tubulin expression were involved in TY04-induced cell cycle arrest.Considering the unique advantages of aptamers,TY04 shows great potential as drug candidate to treat MM.