Activation of aminoflavone (NSC 686288) by a sulfotransferase is required for the antiproliferative effect of the drug and for induction of histone gamma-H2AX.
Aminoflavone (AF) is entering clinical trials. We recently reported that AF induces DNA-protein cross-links (DPC) and gamma-H2AX in MCF-7 human breast cancer cells. To elucidate the mechanism of action of AF and provide biomarkers indicative of AF activity, we correlated AF activity profile (GI(50)) with gene expression patterns in the NCI-60 cell lines. Sulfotransferases (SULT) showed the highest positive correlation coefficients among approximately 14,000 probe sets analyzed (r = 0.537, P < 0.001). Stable transfection of SULT1A1 into AF-resistant MDA-MB-231 cells sensitized these cells to AF. AF produced DPCs, gamma-H2AX foci, and S-phase arrest in the SULT1A1-transfected but not in the parent MDA-MB-231 cells. Conversely, cells in which SULT1A1 was knocked down by small interfering RNA failed to induce gamma-H2AX. Inhibition of SULTs and cytochrome P450 (CYP) enzymes by natural flavonoids blocked the antiproliferative activity of AF and the formation of AF-DNA adducts. AF also induces SULT1A1 and CYP expression in MCF-7 cells, suggesting the existence of an aryl hydrocarbon receptor-mediated positive feedback for AF activation by CYP and SULT1A1. Metabolism studies showed that AF can be oxidized by CYP at two amino groups to form N-hydroxyl metabolites that are substrates for bioactivation by SULTs. We propose that both N-sulfoxy-groups can be further converted to nitrenium ions that form adducts with DNA and proteins. The results reported here show the importance of SULT1A1 and CYP for AF activation and anticancer activity. They also suggest using SULT1A1 and gamma-H2AX as biomarkers for prediction of AF activity during patient selection and monitoring of clinical trials.
Meng
Ling-hua
LH
Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA.
Shankavaram
Uma
U
Chen
Chi
C
Agama
Keli
K
Fu
Hai-qing
HQ
Gonzalez
Frank J
FJ
Weinstein
John
J
Pommier
Yves
Y
D000230:Adenocarcinoma / Q000201:enzymology / Q000473:pathology; D001189:Aryl Hydrocarbon Hydroxylases; D015239:Arylsulfotransferase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D001711:Biotransformation; D001943:Breast Neoplasms / Q000201:enzymology / Q000473:pathology; D045744:Cell Line, Tumor / Q000187:drug effects / Q000201:enzymology; D003432:Cross-Linking Reagents / Q000493:pharmacokinetics* / Q000494:pharmacology; D019363:Cytochrome P-450 CYP1A1 / Q000096:biosynthesis / Q000235:genetics; D065633:Cytochrome P-450 CYP1B1; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000235:genetics; D018736:DNA Adducts; D004273:DNA, Neoplasm / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D025461:Feedback, Physiological; D005260:Female; D005419:Flavonoids / Q000493:pharmacokinetics* / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006657:Histones / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D008862:Microsomes, Liver / Q000201:enzymology; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics; D009369:Neoplasms / Q000201:enzymology / Q000473:pathology; D011355:Prodrugs / Q000493:pharmacokinetics* / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000494:pharmacology; D018336:Receptors, Aryl Hydrocarbon / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000502:physiology
D003432:Cross-Linking Reagents; D018736:DNA Adducts; D004273:DNA, Neoplasm; D005419:Flavonoids; C468783:H2AX protein, human; D006657:Histones; D009363:Neoplasm Proteins; D011355:Prodrugs; D034741:RNA, Small Interfering; D018336:Receptors, Aryl Hydrocarbon; D011993:Recombinant Fusion Proteins; C413760:aminoflavone; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D019363:Cytochrome P-450 CYP1A1; D065633:Cytochrome P-450 CYP1B1; D015239:Arylsulfotransferase; C117544:SULT1A1 protein, human