目的：探讨FOXO3a 在缺氧诱导骨肉瘤细胞顺铂（cisplatin，DDP）耐药中的作用。方法：利用RT-PCR和Western blotting方法检测人骨肉瘤细胞U-2OS在常氧及缺氧条件下FOXO3a 的表达水平，Western blotting 检测转染FOXO3a-siRNA 和HIF-1α-siRNA 对细胞内FOXO3a 和HIF-1α 表达的影响，CCK-8 和Annexin V/PI 染色法检测FOXO3a 在缺氧诱导骨肉瘤细胞DDP耐药中的作用。结果：缺氧可使人骨肉瘤细胞U-2OS中FOXO3a mRNA和蛋白表达升高（均P<0.05）。FOXO3a 的表达受HIF-1α调控，与正常细胞组和转染阴性序列HIF-1α-NC组相比，HIF-1α-siRNA 组FOXO3a 蛋白表达量均显著降低[(0.38±0.03) vs (0.89±0.08)，(0.91±0.07)，均P<0.01]。在缺氧条件下，FOXO3a-siRNA 可降低U-2OS 细胞对DDP 的耐受性[(38.50±2.83)% vs (61.75±5.73)%，P<0.01]，增加DDP诱导的U-2OS细胞凋亡[(73.41±6.13)% vs (32.38±2.23)%, (55.89±4.46)%，均P<0.05]。结论：缺氧通过HIF-1α 依赖的方式诱导骨肉瘤细胞内FOXO3a 表达，从而增强瘤细胞对DPP的耐药性。

Objective:To investigate the role of FOXO3a in hypoxia-induced cisplatin (DDP) resistance in osteosarcoma cells. Methods:The FOXO3a expression was detected by RT-PCR and Western blotting in osteosarcoma U-2OS cell line under normoxia and hypoxia conditions. The effects of HIF-1α-siRNA and FOXO3a-siRNA on the expressions of HIF-1αand FOXO3a were detected by Western blotting. CCK-8 and Annexin V/PI assays were used to detect the function of FOXO3a in hypoxia-induced DDP resistance of U-20S cells. Results: Hypoxia could significantly increase the mRNA and protein levels of FOXO3a in U-2OS cells (All P<0.05). The expression of FOXO3a was regulated by HIF-1α; compared with control group and HIF-1α -NC group, the FOX03a protein expression was significantly down-regulated in HIF-1α-siRNA group [(0.38±0.03) vs (0.89±0.08)，(0.91±0.07), all P<0.01]. Under hypoxia condition,FOXO3a-siRNA could decrease the tolerance of U-2OS cells to DDP [(38.50±2.83)% vs (61.75±5.73)%, P<0.01], and increase DDP-induced apoptosis of U-2OS cells [(73.41±6.13)% vs (32.38±2.23)%, (55.89±4.46)%, All P<0.05]. Conclusions: Hypoxia significantly enhanced DDP-resistance of U-2OS cells by increasing FOXO3a expression in a HIF-1-dependent manner.