白血病细胞株K562中HIF1-α的表达及其对下游基因的影响

The expression of Hypoxia-Inducible Factor-1α and its functional activities in leukemia cell line K562

目的探讨白血病细胞株K562中低氧诱导因子1-α(HIF-1α)表达的增加对下游靶基因的影响及意义。方法氯化钴(CoCl_2)做化学缺氧诱导剂,加入K562细胞培养基,分别培养0、4、8、16 h。Real-Time RT-PCR及Western印迹法分别检测HIF-1αmRNA和蛋白水平的表达。Real-Time RT-PCR检测不同时间HIF-1α下游靶基因VEGF、MDR1/MDR3、survivin、Bcl-2、Caspase-3、Bax等的表达。分析HIF-1α表达的变化对下游基因转录活性的影响和意义。结果随着CoCl_2作用时间的增加,K562细胞HIF-1αmRNA水平表达略有增加,但变化不大(P>0.05),蛋白水平增加明显。下游VEGF、MDR1/MDR3、survivin、Bcl-2转录活性增加(P<0.05),而Bax、Caspase-3表达先增加后减少。结论 CoCl_2主要增加K562细胞株HIF-1α蛋白的表达。HIF-1α蛋白使VEGF、MDR1/MDR3、survivin、Bcl-2等促肿瘤存活基因的转录活性增加,而最终减少了Caspase-3、Bax等促肿瘤细胞凋亡基因的表达。因此,HIF-1α可能是调控白血病进展的关键调节因子。

Objective To study the relationship between the expression of HIF-1αand its target genes in chronic myeloid leukemia cell line K562. Methods COC12 was used as the chemical inducer to mimic hypoxia environment. K562 cells were cultured with COC12 for 0, 4, 8 and 16 h respectively, and recorded as H0h, H4h, H8h and H16h groups. Real-Time RT-PCR and Western blot technique were applied to test the expression of HIF-1α mRNA and protein. The target genes including VEGF, MDRl/MDR3,survivin,Bcl-2,Caspase-3,Bax genes and followed by the analysis of the relationship between HIF-1α expression and target genes controlled by HIF-1α were estimated by Real-Time RT-PCR. Results Among H0h, H4h, H8h, and Hl6h groups, levels of HIF-1α mRNA remained the same（P〉0.05）, whereas its protein increased evidently. The transcriptional activities of VEGF,MDR1/ MDR3 ,survivin,Bcl-2 mRNA were elevated（P〈0.01）,whereas Caspase-3,Bax genes increased in H0h and H4h groups, but decreased in HSh and H16h groups（P〈0.01）.Conclusion CoCl2 chiefly enhances the expression of HIF-1α protein in K562 cells. The genes regulated by HIF-1α are markedly changed in mRNA levels influencing greatly on survive or apoptosis of leukemia cell line K562. HIF-1α protein may be the important factor on leukemia development.