Modulation of P-glycoprotein activity by the substituted quinoxalinone compound QA3 in adriamycin-resistant K562/A02 cells.
QA3 is a derivative of the substituted 1,3-dimethyl-1H-quinoxalin-2-ones, which are compounds that may selectively antagonize P-glycoprotein (P-gp) in multidrug resistance (MDR) cancer cells. Our previous work identified QA3 as a candidate compound for reversing MDR in cancer cells. In the present study, we found that QA3 significantly decreases the intracellular level of ATP, stimulates ATPase activity in membrane microsomes and decreases protein kinase C (PKC) activity. These results indicated that QA3 inhibits P-gp activity by blocking ATP hydrolysis and ATP regeneration. Furthermore, QA3 triggered and increased adriamycin-induced K562/A02 cell apoptosis as evidenced by Annexin V-FITC plus PI staining.Western blot analysis showed that the levels of cleaved caspase-9 and cleaved caspase-3 proteins increased, and similarly, the levels of procaspase-9 and procaspase-3 decreased after QA3 treatment. Consequently, poly ADP-ribose polymerase (PARP) activity increased as evidenced by the presence of the PARP cleavage product in K562/A02 cells. QA3 also enhanced the potency of adriamycin against K562/A02 cells as demonstrated by increased apoptosis and activation of caspase-9,-3 and PARP. These data support the observation that P-gp activity is inhibited after QA3 treatment. Moreover, these results indicate that QA3 is a novel MDR reversal agent with potent inhibitory action against P-gp MDR cancer cells.
Department of Pharmacology, School of Pharmaceutical Sciences, Shandong University, Jinan, China.
Li-Rui
LR
Sun
Julia Li
JL
Zhong
Shu-Xiang
SX
Cui
Xun
X
Li
Stephen Geoffrey
SG
Ward
Yan-Qiu
YQ
Shi
Xiao-Fan
XF
Zhang
Yan-Na
YN
Cheng
Jian-Jun
JJ
Gao
Xian-Jun
XJ
Qu
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors*; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000032:analysis; D017209:Apoptosis / Q000187:drug effects; D020169:Caspases / Q000502:physiology; D004317:Doxorubicin / Q000494:pharmacology*; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D006801:Humans; D020014:K562 Cells; D011493:Protein Kinase C / Q000378:metabolism; D011810:Quinoxalines / Q000494:pharmacology
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D011810:Quinoxalines; D004317:Doxorubicin; D000255:Adenosine Triphosphate; D011493:Protein Kinase C; D020169:Caspases; D000251:Adenosine Triphosphatases