The interaction of telomere DNA G-quadruplex with three bis-benzyltetrahydroisoquinoline alkaloids.
Telomeres are important multifunctional nucleoprotein structures located at the ends of eukaryotic chromosomes. Telomerase regulates telomere elongation, and its activity is associated with tumorigenesis. Because the activity of telomerase can be inhibited by G-quadruplex (G4) formation (a four-stranded DNA with stacks of G-quartets formed by four guanines in a planar structure), the role of G4 in cancer therapy has attracted many research interests. We studied the effects of three natural alkaloids-tetrandrine, fangchinoline, and berbamine-on the stability and formation of telomere DNA G4 with circular dichroism melting spectroscopy (melting-CD), variable temperature ultraviolet (melting-UV), proton nuclear magnetic resonance spectroscopy ((1)H NMR), and molecular docking, and examined the relationships among the alkaloid structure and their activities. We further investigated their cytotoxicity with the 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT) and flow cytometry (FCM). The results demonstrated that alkaloids increased G4 stability and induced its formation, which added structure diversity of G4-ligands. The results showed that -OH at R(1), -OCH(3) at R(2), and [Formula: see text] at R(3) had higher stability than other substituent groups for these alkaloids. We also found a transition of antiparallel to parallel G4 as the temperature increased. The result indicated the possible advantage of parallel G4 in adversity. In addition, the alkaloids demonstrated a moderate cytotoxicity and proved to be cell cycle blocker in the G(1) phase. These alkaloids have revealed promising potentials to be the agents for antitumor therapy.
Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, Beijing Key Laboratory of Gene Engineering Drugs & Biological Technology College of Life Science, Beijing Normal University, Beijing, People's Republic of China.
Xiaohui
X
Ji
Jiejun
J
Chen
Hongxia
H
Sun
Huaxi
H
Zhou
Junfeng
J
Xiang
An
A
Peng
Yalin
Y
Tang
Changqi
C
Zhao
D000470:Alkaloids / Q000008:administration & dosage / Q000032:analysis* / Q000737:chemistry*; D044182:Benzylisoquinolines / Q000008:administration & dosage / Q000032:analysis / Q000737:chemistry; D059447:Cell Cycle Checkpoints / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects*; D002478:Cells, Cultured; D004847:Epithelial Cells; D054856:G-Quadruplexes / Q000187:drug effects*; D006801:Humans; D015394:Molecular Structure; D016615:Telomere / Q000737:chemistry*
D000470:Alkaloids; D044182:Benzylisoquinolines; C009438:tetrandrine; C060802:fangchinoline; C027870:berbamine