Lu Xu-jing, Xu Wen-lin, Luo Wen-juan, Wang Fa-chun, Chen Qiao-yun
Department of Hematology, the Affiliated People's Hospital of Jiangsu University, Zhenjiang 212002, China.
Zhonghua Xue Ye Xue Za Zhi. 2008 Jul;29(7):468-71.
To investigate the effect of tetrandrine (TTD) on doxorubicin-induced mdr1 gene expression and its mechanism.
MTT assay was used to detect the cytotoxicity of TTD to K562 cells. K562 cells were treated with doxorubicin alone or 0.6 microg/ml doxorubicin combined with various concentrations of TTD. RT-PCR was used to detect the mRNA expression of mdr1 and NF-kappa B. Flow cytometry was used to assay the expression of P-glycoprotein (P-gp). Intracellular rhodamine 123 (Rho123) retention assay was applied to test the P-gp function.
After treatment with 0.6 microg/ml doxorubicin for 24 hours, the expressions of mdr1 mRNA, NF-kappa B mRNA and P-gp in K562 cells were increased from 0.171 +/- 0.012, 0.783 +/- 0.090, 7.85 +/- 0.15 to 0.428 +/- 0.012, 1.075 +/- 0.047 and 73.68 +/- 1.84, respectively. The intracellular Rho123 retention was decreased from 711.9 +/- 63.6 to 347.8 +/- 60.6, indicating up-regulation of P-gp function (P<0.05). Pretreatment of K562 cells with 2.0 microg/ml TTD for 24 hours and then incubated for another 24 h with doxorubicin, the expressions of mdr1 mRNA, NF-kappa B mRNA, P-gp and up-regulation of P-gp function induced by doxorubicin were prevented in K562 cells (0.148 +/- 0.006, 0.627 +/- 0.098, 7.18 +/- 0.38 and 799.7 +/- 45.8, respectively P<0.05). But 0.5 microg/ml and 1.0 microg/ml TTD had little effect.
TTD inhibits the expression of mdr1 mRNA, P-gp and up-regulated P-gp function induced by doxorubicin in a dose dependent manner. The mechanism of this effect may be down-regulation of NF-kappa B by TTD.
研究粉防己碱（TTD）对阿霉素诱导的mdr1基因表达的影响及其机制。
采用MTT法检测TTD对K562细胞的细胞毒性。K562细胞分别单独用阿霉素处理或用0.6μg/ml阿霉素与不同浓度的TTD联合处理。采用RT-PCR法检测mdr1和NF-κB的mRNA表达。采用流式细胞术检测P-糖蛋白（P-gp）的表达。应用细胞内罗丹明123（Rho123）保留试验检测P-gp功能。
用0.6μg/ml阿霉素处理24小时后，K562细胞中mdr1 mRNA、NF-κB mRNA和P-gp的表达分别从0.171±0.012、0.783±0.090、7.85±0.15增加到0.428±0.012、1.075±0.047和73.68±1.84。细胞内Rho123保留率从711.9±63.6降至347.8±60.6，表明P-gp功能上调（P<0.05）。用2.0μg/ml TTD预处理K562细胞24小时，然后再用阿霉素孵育24小时，可抑制K562细胞中阿霉素诱导的mdr1 mRNA、NF-κB mRNA、P-gp表达及P-gp功能上调（分别为0.148±0.006、0.627±0.098、7.18±0.38和799.7±45.8，P<0.05）。但0.5μg/ml和1.0μg/ml TTD作用不明显。
TTD以剂量依赖性方式抑制阿霉素诱导的mdr1 mRNA、P-gp表达及P-gp功能上调。其作用机制可能是TTD下调NF-κB。
