Salvicine functions as novel topoisomerase II poison by binding to ATP pocket.
Salvicine, a structurally modified diterpenoid quinone derived from Salvia prionitis, is a nonintercalative topoisomerase II (topo II) poison. The compound possesses potent in vitro and in vivo antitumor activity with a broad spectrum of anti-multidrug resistance activity and is currently in phase II clinical trials. To elucidate the distinct antitumor properties of salvicine and obtain valuable structural information of salvicine-topo II interactions, we characterized the effects of salvicine on human topo IIalpha (htopo IIalpha), including possible binding sites and molecular interactions. The enzymatic assays disclosed that salvicine mainly inhibits the catalytic activity with weak DNA cleavage action, in contrast to the classic topo II poison etoposide (VP16). Molecular modeling studies predicted that salvicine binds to the ATP pocket in the ATPase domain and superimposes on the phosphate and ribose groups. In a surface plasmon resonance binding assay, salvicine exhibited higher affinity for the ATPase domain of htopo IIalpha than ATP and ADP. Competitive inhibition tests demonstrated that ATP competitively and dose-dependently blocked the interactions between salvicine and ATPase domain of htopo IIalpha. The data illustrate that salvicine shares a common binding site with ATP and functions as an ATP competitor. To our knowledge, this is the first report to identify an ATP-binding pocket as the structural binding motif for a nonintercalative eukaryotic topo II poison. These findings collectively support the potential value of an ATP competitor of htopo IIalpha in tumor chemotherapy.
Hu
Chao-Xin
CX
Division of Antitumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, PR China.
Zuo
Zhi-Li
ZL
Xiong
Bing
B
Ma
Jin-Gui
JG
Geng
Mei-Yu
MY
Lin
Li-Ping
LP
Jiang
Hua-Liang
HL
Ding
Jian
J
D000251:Adenosine Triphosphatases / Q000302:isolation & purification / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000951:Antigens, Neoplasm / Q000737:chemistry / Q000378:metabolism*; D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D001665:Binding Sites; D002384:Catalysis; D004247:DNA / Q000737:chemistry; D004250:DNA Topoisomerases, Type II / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006868:Hydrolysis; D008958:Models, Molecular; D009285:Naphthoquinones / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D009690:Nucleic Acid Conformation; D017434:Protein Structure, Tertiary; D059005:Topoisomerase II Inhibitors
D000951:Antigens, Neoplasm; D000972:Antineoplastic Agents, Phytogenic; D004268:DNA-Binding Proteins; D009285:Naphthoquinones; D059005:Topoisomerase II Inhibitors; C122096:salvicine; D000255:Adenosine Triphosphate; D004247:DNA; D000251:Adenosine Triphosphatases; D004250:DNA Topoisomerases, Type II