Effects of imatinib and 5-bromotetrandrine on the reversal of multidrug resistance of the K562/A02 cell line.
OBJECTIVE
Research has shown that 5-bromotetrandrine (BrTet) can effectively reverse multidrug resistance (MDR). Imatinib plays an important role in cell proliferation. This study explored the efficacy of the combination of imatinib and BrTet on reversing MDR of tumor cells and its mechanism.


METHODS
Cytoxicity was assessed by MTT assay. Apoptosis of K562/A02 cells was analyzed by flow cytometry. The expressions of mdr1 mRNA and P-glycoprotein (P-gp) were detected using reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis.


RESULTS
After 48 h of treatment with 0.0625 micromol/L imatinib, 0.5 micromol/L BrTet, or both, the 50% inhibition concentration (IC50) of daunorubicin (DNR) for the K562/A02 cells were 5.69 mg/L, 5.41 mg/L, and 2.19 mg/L, respectively. The gray-scale values of mdr1 mRNA expression in the K562/A02 cells were 0.65+/-0.02, 0.64+/-0.01, and 0.25+/-0.03, respectively. The expression levels of P-gp were 0.74+/-0.02, 0.52+/-0.02, and 0.29+/-0.02, respectively. All decreased significantly in the K562/A02 cells treated with both imatinib and BrTet compared to cells treated with imatinib and BrTet alone (P<0.05). The apoptosis rates of the K562/A02 cells increased without a significant difference after treatment with DNR, imatinib, or BrTet (P>0.05), while increased significantly after treatment with DNR combined with imatinib, BrTet, or both (P<0.05).


CONCLUSIONS
The MDR of K562/A02 cells may be partially reversed by imatinib or BrTet, and the mechanism may be related to the downregulation of mdr1 mRNA and P-gp expression and the upregulation of the rate of apoptosis in K562/A02 cells. Imatinib combined with BrTet showed a synergistic effect on K562/A02 cells.
Department of Hematology, Zhongda Hospital, Medical College, Southeast University, Nanjing, Jiangsu 210009, PR China. cba8888@hotmail.com
Bao-An
BA
Chen
Xue-Yun
XY
Shan
Jian
J
Chen
Guo-Hua
GH
Xia
Wen-Lin
WL
Xu
Michael
M
Schmit
D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism*; D000903:Antibiotics, Antineoplastic / Q000493:pharmacokinetics / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001549:Benzamides; D044182:Benzylisoquinolines / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D003630:Daunorubicin / Q000493:pharmacokinetics / Q000494:pharmacology; D015536:Down-Regulation; D018432:Drug Resistance, Multiple / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004357:Drug Synergism; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D000068877:Imatinib Mesylate; D020014:K562 Cells / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism
C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D000970:Antineoplastic Agents; D001549:Benzamides; D044182:Benzylisoquinolines; D010879:Piperazines; D011743:Pyrimidines; D012333:RNA, Messenger; C514835:bromotetrandrine; D000068877:Imatinib Mesylate; D003630:Daunorubicin