[Study on reversing mechanism of multidrug resistance of K562/A02 cell line by carnosic acid].
OBJECTIVE
To investigate the effects of carnosic acid (CA) on reversal of the multidrug resistance (MDR) of human leukemia cell line K562/A02 and its mechanism.


METHODS
MTT assay was used to determine the sensitivity of K562/A02 cells to adriamycin (ADM) pre-and post-treated with CA. Flow cytometry (FCM) and laser scanning confocal microscopy (LSCM) were used to measure intracellular fluorescence intensity and concentration of ADM respectively. The expression level of mdr1 was detected by semi-quantitative RT-PCR. P-glycoprotein (P-gp) expression was detected by FCM and Western blot.


RESULTS
CA decreased IC(50) of ADM in K562/A02 cells from 16.31 µg/mL to 1.35 µg/mL, being a 12.08-fold decrease. The intracellular ADM fluorescence intensity of K562/A02 was increased from 17.05 to 60.53 after treated with CA (P < 0.01). In living K562/A02 cells, after treated with CA, the diffuse distribution of intracellular ADM was recovered in both nuclear and cytoplasm, and the concentration of intracellular ADM increased from 4.93µg/mL to 15.43µg/mL. RT-PCR assay showed that CA inhibited the expressions of mdr1 mRNA in K562/A02 cells (P < 0.01). Mean fluorescence intensity of P-gp detected by FCM in CA-treated K562/A02 was decreased to 22.80 as compared with that in untreated K562/A02 cells (44.40, P < 0.05).


CONCLUSIONS
CA can reverse the MDR of K562/A02 cells in vitro. The mechanism may be associated with down-regulation of mdr1 and inhibition of P-gp function.
Department of Hematology, Qilu Hospital, Shandong University, Jinan 250012, China.
Xiao-Ning
XN
Yu
Hao
H
Li
Xue-Liang
XL
Chen
Xiang-Xin
XX
Li
Ran
R
Wang
Fang
F
Gao
D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D006801:Humans; D020014:K562 Cells
D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D004317:Doxorubicin