[Effect of tetrandrine on the doxorubicin-induced expression of mdr1 gene in K562 cells].
OBJECTIVE
To investigate the effect of tetrandrine (TTD) on doxorubicin-induced mdr1 gene expression and its mechanism.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Lu
Xu-jing
XJ
Department of Hematology, the Affiliated People's Hospital of Jiangsu University, Zhenjiang 212002, China.
Xu
Wen-lin
WL
Luo
Wen-juan
WJ
Wang
Fa-chun
FC
Chen
Qiao-yun
QY
D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism*; D044182:Benzylisoquinolines / Q000494:pharmacology*; D004317:Doxorubicin / Q000494:pharmacology; D006801:Humans; D020014:K562 Cells; D016328:NF-kappa B / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects
C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D044182:Benzylisoquinolines; D016328:NF-kappa B; D012333:RNA, Messenger; C009438:tetrandrine; D004317:Doxorubicin