Background and purpose: MicroRNA(miRNA) is a class of small non-coding RNA playing an important regulatory role in many tumors. This study investigated which miRNA might negatively regulate the expression of Aurora-B in osteosarcoma cells

and to lay the foundation for the further investigation of the effort and regulation of Aurora-B in osteosarcoma malignant phenotype. Methods: Bioinformatics prediction software (http://www.targetscan.org) and luciferase assays were used to investigate which miRNA might target to modulate the Aurora-B. Real-time fluorescent quantitative polymerase chain reaction (RTFQ-PCR) and Western blot assay were used to further verify which miRNA could negative regulate the expression of Aurora-B gene. Results: Bioinformatics prediction showed let-7 family have the possibility to modulate the expression of Aurora-B; Luciferase assays showed that Aurora-B might be the target gene of let-7a/b/c/d/e/f/g/i; RTFQ-PCR and Western blot analysis testified that both the expression levels of Aurora-B mRNA and Aurora-B protein were significantly decreased in Let-7a/g/i up-regulated U2-OS and HOS cells

compared to the cells in the negative control group; but in Let-7b/c/d/e/f up-regulated U2-OS and HOS cells

the expression levels of Aurora-B mRNA and Aurora-B protein have no significant difference

compared to the cells in the negative control group. Conclusion: Let-7a/g/i may downregulate the expression of Aurora-B in human osteosarcoma cells.