The reversal effects of 3-bromopyruvate on multidrug resistance in vitro and in vivo derived from human breast MCF-7/ADR cells.
OBJECTIVE
P-glycoprotein mediated efflux is one of the main mechanisms for multidrug resistance in cancers, and 3-Bromopyruvate acts as a promising multidrug resistance reversal compound in our study. To test the ability of 3-Bromopyruvate to overcome P-glycoprotein-mediated multidrug resistance and to explore its mechanisms of multidrug resistance reversal in MCF-7/ADR cells, we evaluate the in vitro and in vivo modulatory activity of this compound.


METHODS
The in vitro and in vivo activity was determined using the MTT assay and human breast cancer xenograft models. The gene and protein expression of P-glycoprotein were determined using real-time polymerase chain reaction and the Western blotting technique, respectively. ABCB-1 bioactivity was tested by fluorescence microscopy, multi-mode microplate reader, and flow cytometry. The intracellular levels of ATP, HK-II, and ATPase activity were based on an assay kit according to the manufacturer's instructions.


RESULTS
3-Bromopyruvate treatment led to marked decreases in the IC50 values of selected chemotherapeutic drugs [e.g., doxorubicin (283 folds), paclitaxel (85 folds), daunorubicin (201 folds), and epirubicin (171 folds)] in MCF-7/ADR cells. 3-Bromopyruvate was found also to potentiate significantly the antitumor activity of epirubicin against MCF-7/ADR xenografts. The intracellular level of ATP decreased 44%, 46% in the presence of 12.5.25 µM 3-Bromopyruvate, whereas the accumulation of rhodamine 123 and epirubicin (two typical P-glycoprotein substrates) in cells was significantly increased. Furthermore, we found that the mRNA and the total protein level of P-glycoprotein were slightly altered by 3-Bromopyruvate. Moreover, the ATPase activity was significantly inhibited when 3-Bromopyruvate was applied.


CONCLUSIONS
We demonstrated that 3-Bromopyruvate can reverse P-glycoprotein-mediated efflux in MCF-7/ADR cells. Multidrug resistance reversal by 3-Bromopyruvate occurred through at least three approaches, namely, a decrease in the intracellular level of ATP and HK-II bioactivity, the inhibition of ATPase activity, and the slight decrease in P-glycoprotein expression in MCF-7/ADR cells.
Department of Clinical Pharmacology, College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China.
Long
L
Wu
Department of Clinical Pharmacology, College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China.
Jun
J
Xu
Department of Clinical Pharmacology, College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China.
Weiqi
W
Yuan
Division of Pharmaceutics, College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China.
Baojian
B
Wu
School of Pharmaceutical Sciences, Sun Yat-sen University, Guang Zhou 510275, P. R. China.
Hao
H
Wang
Department of Clinical Pharmacology, College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China.
Guangquan
G
Liu
Department of Clinical Pharmacology, College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China.
Xiaoxiong
X
Wang
School of Pharmaceutical Sciences, Sun Yat-sen University, Guang Zhou 510275, P. R. China.
Jun
J
Du
Department of Clinical Pharmacology, College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China.
Shaohui
S
Cai
D018435:ATP Binding Cassette Transporter, Subfamily B / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000401:mortality; D045744:Cell Line, Tumor; D018432:Drug Resistance, Multiple / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011773:Pyruvates / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays
C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D009363:Neoplasm Proteins; D011773:Pyruvates; C017092:bromopyruvate