The Inhibitory Effects Of Genistein On The Expression Of HIF-1α And MDR1 In CoCl₂ Induced K562 Cells

Objectives:To examine the mechanism of genistein(gen) reversing MDR, we investigated the effect of gen on the expression of hypoxia inducible factor-1α(HIF-1α) and multidrug resistance (MDR1) in human leukemia cell line K562,under the hypoxia condition simulated by cobalt chloride (CoCl₂).Subject:Human leukemia cell line:K562 .Methods:The hypoxia condition was simulated by CoCl₂. For all experimental procedures, approximately 106 cells were seeded in 25 cm2 flasks containing 5 ml of medium. The dose-effect and time-effect groups were prepared as follows: the former were exposed to 0, 50, 100 and 150μmol/L of CoCl₂ for 72h, the latter were detected at 0, 24, 48 and 72h while treated with CoCl₂ 100μmol/L. The gen treated samples were divided into five groups:â‘ normal control;â‘¡CoCl₂ 150μmol/L;â‘¢CoCl₂ 150μmol/L / gen 50μmol/L;â‘£CoCl₂ 150μmol/L / gen 100μmol/L;⑤CoCl₂ 150μmol/L / gen 200μmol/L.The HIF-1αand MDR1/ P-gp were detected by RT-PCR and Western Blot.Results:1. As the dose and time exposed to CoCl₂ increased, the expression of HIF-1αmRNA in K562 cell remained the similar level (P>0.05), while the HIF-1αprotein expression increased markedly (P<0.01).2. Although no bands for MDR1 mRNA and P-gp were observed under normoxic conditions in K562 cells, the expression of MDR1 mRNA and P-gp increased significantly with the increases of dose and time treated with CoCl₂ (P<0.01). 3. Gen significantly inhibited the expression of HIF-1αprotein and MDR1/ P-gp induced by CoCl₂ in a dose-dependent manner (P<0.01) while the HIF-1αmRNA expression was not affected by treatment of gen (P>0.05). Moreover,the dosage of gen was significantly negatively correlated with expression of HIF-1αprotein and MDR1/ P-gp (γ2 =-0.947, -0.992 and -0.938 respectively, P<0.01). And the expression of HIF-1αprotein was significantly positively correlated with the expression of MDR1/P-gp(γ2 = 0.935 and 0.942 respectively,P<0.01)Conclusions:1. These results show that CoCl₂ dose- and time-dependently induced the HIF-1αprotein expression; HIF-1αmRNA was constantly expressed regardless of normoxic conditions or in the presence of cobalt ion under normoxic conditions.2. These results show that CoCl₂ induced MDR1/P-gp expression in a time- and dose-dependent manner.3. Gen inhibited the expression of HIF-1αprotein and MDR1/ P-gp in a dose-dependent manner while the HIF-1αmRNA expression was not affected by treatment of gen.4. Gen may suppress the expression of MDR1/ P-gp via down-regulation of HIF-1αprotein.