中文摘要：

背景与目的 MicroRNA145（miRNA145）是microRNA家族中的重要一员,已被证实在多种肿瘤细胞中呈现低表达,并认为miRNA 145作为一种抑癌基因可以影响肿瘤细胞的生长和侵袭能力,但其在骨肉瘤中的作用未见相关报道.该研究旨在探讨miRNA145对骨肉瘤细胞增殖、细胞周期以及凋亡的影响.方法 用脂质体法将miRNA145真核表达质粒瞬时转染入人骨肉瘤细胞（MG63）,实验设置空白对照组、空载体转染组和miRNA145质粒转染组3组,转染后荧光显微镜下观察转染效率,实时定量RT-PCR检测各组细胞miRNA145的表达,MTT增殖实验检测各组细胞的增殖情况,流式细胞仪检测各组细胞周期及细胞凋亡率.结果 转染后miRNA145质粒转染组细胞增殖速度明显下降,细胞周期停止在G1期之前,凋亡率增高,差异有统计学意义（P〈0.05）.结论 miRNA145可以有效地抑制骨肉瘤细胞的增殖,促进细胞凋亡.

英文摘要：

Background and purpose： MicroRNA145 （miRNA145）, an important member in the family of miRNAs, is under-expressed in several types of tumors and acts as a tumor suppressor. The role and probable pathway of miRNA145 in osteosarcoma carcinogenesis is still unknown. Our previous study was to investigate the effects of miRNA145 on proliferation and apoptosis of osteosarcoma cells （MG63）. Methods： MG63 cells were randomly allocated into 3 groups： blank group, empty vector transfected group and miRNA145 expression plasmid transfected group. Under the induction of LipofectamineTM 2000, the recombinant was transfected into MG63. After transfection, transfection efficiency was observed by GFP. MiRNA145 expression level was detected by real-time quantitative RT- PCR. Cell proliferation was detected by MTT proliferation assay. Cell cycle and apoptosis were detected by flow cytometry. Results： Compared with negative control, miRNA145 expression were up-regulated by 277% （P〈0.01）. Meanwhile, cell proliferation, cycle and apoptosis of osteosarcoma cells were all significantly inhibited （P〈0.01）. Conclusion： miRNA145 can dramatically inhibit proliferation and apoptosis ofosteosarcoma cells.