垂体肿瘤转化基因1表达下调对骨肉瘤细胞增殖、细胞周期和细胞侵袭能力的影响及其分子机制

Impact of PTTG1 downregulation on cell proliferation, cell cycle and cell invasion of osteosarcoma and related molecular mechanisms

目的 利用垂体肿瘤转化基因1（PTTG1） siRNA下调骨肉瘤细胞中PTTG1的表达,研究其表达下调对骨肉瘤细胞增殖、细胞周期和细胞侵袭能力的影响,并探讨其可能的分子机制.方法 采用Western blot检测3株骨肉瘤细胞（MG-63、SaOS-2和U2OS）和1株成骨细胞hFOB1.19中PTTG1蛋白的表达.用对照和PTTG1 siRNA转染骨肉瘤U2OS细胞,采用Western blot检测转染前后PTTG1蛋白的表达水平,分别利用细胞增殖与活性检测试剂盒、流式细胞术和Boyden小室检测PTTG1 siRNA对骨肉瘤U2OS细胞增殖、细胞周期和侵袭能力的影响,采用Western blot检测不同处理的U2OS细胞中Akt的活化状态及其下游靶基因的表达.结果 3株骨肉瘤细胞MG-63、SaOS-2和U2OS中PTTG1蛋白表达均高于成骨细胞hFOB1.19,其中U2OS中表达较高.PTTG1 siRNA能显著下调骨肉瘤U2OS细胞中PTTG1蛋白的表达,抑制U2OS细胞的增殖、改变细胞周期分布并降低侵袭能力.此外,PTTG1表达下调能抑制骨肉瘤细胞中p-Akt（S473和T308）、基质金属蛋白酶（MMP-2）和MMP-9的表达,提高p21和上皮性钙黏蛋白（E-cadherin）的表达.结论 PTTG1可能与骨肉瘤的发生发展关系密切,有望为骨肉瘤分子靶向治疗提供新策略.

Objective To downregulate the expression of pituitary tumor transforming gene 1 （PTTG1） in osteosarcoma （OS） cells by siRNA technology and to investigate related biological impact on cell proliferation,cell cycle and cell invasion of OS.Methods Three OS cell lines and osteoblast hFOB1.19 cell line were used in this study.Control siRNA and PTTG1 siRNA were employed to transfect OS U2OS cells,and PTTG1 protein level was detected by Western blot after the transfection.Effects of PTTG1 siRNA on cell proliferation,cell cycle and cell invasion were investigated by CCK-8,flow cytometry and Boyden chamber,respectively.Finally,activity of Akt and its downstream target gene expression were analyzed by Western blot in U2OS cells upon various treatments.Results Expression of PTTG1 protein in 3 OS cells （MG-63,SaOS-2 and U2OS） was significantly higher than that in osteoblast hFOB1.19,among which U2OS cells displayed the highest level.PTTG1 siRNA markedly downregulated the expression of PTTG1 protein in U2OS cells,leading to obvious inhibition of cell proliferation,altered cell cycle distribution and reduced ability of invasion of U2OS cells.Moreover,downregulation of PTTG1 reduced the expression of p-Akt （S473 and T308）,MMP-2 and MMP-9 proteins,along with enhanced expression of p21 and E-cadherin proteins.Conclusions PTTG1 may be tightly linked to the development of OS and therefore may serve as a novel target for precision therapy of OS.