Structure-activity relationships (SAR) in the aurone pharmacophore identified heterocyclic variants of the (Z)-2-benzylidene-6-hydroxybenzofuran-3(2H)-one scaffold that possessed low nanomolar in vitro potency in cell proliferation assays using various cancer cell lines, in vivo potency in prostate cancer PC-3 xenograft and zebrafish models, selectivity for the colchicine-binding site on tubulin, and absence of appreciable toxicity. Among the leading, biologically active analogs were (Z)-2-((2-((1-ethyl-5-methoxy-1H-indol-3-yl)methylene)-3-oxo-2,3-dihydrobenzofuran-6-yl)oxy)acetonitrile (5a) and (Z)-6-((2,6-dichlorobenzyl)oxy)-2-(pyridin-4-ylmethylene)benzofuran-3(2H)-one (5b) that inhibited in vitro PC-3 prostate cancer cell proliferation with IC50 values below 100 nM. A xenograft study in nude mice using 10 mg/kg of 5a had no effect on mice weight, and aurone 5a did not inhibit, as desired, the human ether-à-go-go-related (hERG) potassium channel. Cell cycle arrest data, comparisons of the inhibition of cancer cell proliferation by aurones and known antineoplastic agents, and in vitro inhibition of tubulin polymerization indicated that aurone 5a disrupted tubulin dynamics. Based on molecular docking and confirmed by liquid chromatography-electrospray ionization-tandem mass spectrometry studies, aurone 5a targets the colchicine-binding site on tubulin. In addition to solid tumors, aurones 5a and 5b strongly inhibited in vitro a panel of human leukemia cancer cell lines and the in vivo myc-induced T cell acute lymphoblastic leukemia (T-ALL) in a zebrafish model.
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C.L. and D.S.W. were supported by NIH R01 CA172379. D.S.W. was also supported by the Office of the Dean of the College of Medicine, the Markey Cancer Center, and the Center for Pharmaceutical Research and Innovation (CPRI) in the College of Pharmacy, NIH R21 CA205108 (to J. Mohler), Department of Defense Idea Development Award PC150326P2, and NIH P20 RR020171 from the National Institute of General Medical Sciences (to L. Hersh). The authors also thank the University of Kentucky Proteomics Core mass spectrometric measurements using a LTQ-Orbitrap mass spectrometer that was acquired by NIH grant S10 RR029127 to Professor H. Zhu. This research was also supported by the Flow Cytometry and Cell Sorting Shared Resource Facility of the University of Kentucky Markey Cancer Center (P30CA177558).
The data related to this manuscript during the current study are available from the corresponding authors on reasonable request.
Supplementary information accompanies this paper at https://doi.org/10.1038/s41598-019-42917-0.
Xie, Yanqi; Kril, Liliia M.; Yu, Tianxin; Zhang, Wen; Frasinyuk, Mykhaylo S.; Bondarenko, Svitlana P.; Kondratyuk, Kostyantyn M.; Hausman, Elizabeth; Martin, Zachary M.; Wyrebek, Przemyslaw P.; Liu, Xifu; Deaciuc, Agripina G.; Dwoskin, Linda P.; Chen, Jing; Zhu, Haining; Zhan, Chang-Guo; Sviripa, Vitaliy M.; Blackburn, Jessica S.; Watt, David S.; and Liu, Chunming, "Semisynthetic Aurones Inhibit Tubulin Polymerization at the Colchicine-Binding Site and Repress PC-3 Tumor Xenografts in Nude Mice and Myc-Induced T-ALL in Zebrafish" (2019). Molecular and Cellular Biochemistry Faculty Publications. 169.