Design, synthesis of 4,5-diazafluorene derivatives and their anticancer activity via targeting telomeric DNA G-quadruplex

• Published in: European journal of medicinal chemistry 2019-09, Vol.178, p.484-499
• Main Authors: Zhou, Kang, Liu, Jiachun, Xiong, Xuqiong, Cheng, Mei, Hu, Xiaolin, Narva, Suresh, Zhao, Xiaoyin, Wu, Yanling, Zhang, Wen
• Format: Article
• Language: English
• Subjects: 4,5-Diazafluorene; Antiproliferative activity; Cancer cells; Telomerase activity; Telomeric G-quadruplex
• ISSN: 0223-5234; 1768-3254
• DOI: 10.1016/j.ejmech.2019.06.012

In our work, 19 novel 4,5-diazafluorene derivatives (11a-d, 12a-d, 13a-d, 14a-c, 15c, 16a-c) bearing a 1,3-disubstituted pyrazol/thioxothiazolidinone or thioxothiazolidinone-oxadiazole moieties were designed, synthesized, preliminarily explored for their antitumor activities and in vitro mechanism. All compounds showed different values of antiproliferative activity against A549, AGS, HepG2 and MCF-7 cell lines through CCK-8. Especially, the compound 14c exhibited the strongest activity and best selectivity against A549 cells with an IC50 1.13 μM and an SI value of 7.01 relative to MRC-5 cells, which was better than cisplatin (SI = 1.80) as a positive control. Experimental results at extracellular level demonstrated that compounds 14a-c could strongly interact with the G-quadruplex(es) formed in a 26 nt telomeric G-rich DNA, in particular, the 14c exhibits quite strong binding affinity with an association equilibrium constant (KA) of 7.04(±0.16) × 107 M−1 and more than 1000-fold specificity to G4-DNA over ds-DNA and Mut-DNA at the compound/G4-DNA ratio of 1:1. Further trap assay ascertained that compounds 14a-c owned strong inhibitory ability of telomerase activity in A549 cells, suggesting that these compounds have great possibility to target telomeric G-quadruplexes and consequently indirectly inhibit the telomerase activity. In addition, it is worthy of note that the remarkable inhibitory effects of 14a-c on the mobility of tested cancer cells were observed by wound healing assays. Furthermore, molecular docking and UV–Vis spectral results unclose the rationale for the interaction of compounds with such G-quadruplex(es). These results indicate that the growth and metastasis inhibition of cancer cells mediated by these 4,5-diazafluorene derivatives possibly result from their interaction with telomeric G-quadruplexes, suggesting that 4,5-diazafluorene derivatives, especially 14c, possess potential as anticancer drugs. This kind of 4,5-diazafluorene derivatives with an extended planar aromatic system can interact with the telomeric G-quadruplexes, inhibit the telomerase activity and consequently cancer cells proliferation. [Display omitted] •19 novel 4,5-diazafluorene derivatives were synthesized.•14c showed strongest inhibitory activity with an IC50 of 1.13 μM against A549 cells.•The compounds could stabilize telomeric G4-DNA’s and inhibit telomerase activity.