Riccardin D, a macrocyclic bisbibenzy, inhibits human breast cancer growth through the suppression of telomerase activity.
Riccardin D, a liverwort-derived naturally occurring macrocyclic bisbibenzyl, has been found to exert anticancer effects in multiple cancer cell types. In this study, we investigated the effect and mechanism of Riccardin D on human breast cancer. Experiments were performed on human breast cancer MCF-7 and MDA-MB-231 cells. The antitumour effects of Riccardin D were assessed by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay and human breast cancer xenografts mice model. TRAPeze(®) XL Telomerase Detection assay was used for the detection of telomerase activity. γ-H2 AX foci formation was tested for the induction of DNA damage response. Cell cycle distribution was analysed by flow cytometry, and cell apoptosis was determined by annexin V-FITC/PI staining, terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) assay and Western blotting. Riccardin D effectively inhibited the growth of MCF-7 and MDA-MB-231 cells in vitro. And Riccardin D also effectively delayed the growth of MCF-7 and MDA-MB-231-luc-D3H2LN xenografts without significant loss of body-weight. Further analysis suggested that Riccardin D's effects may arise from its suppression of telomerase activity, which led to telomere dysfunction. Telomerase inhibition and telomere dysfunction could activate the canonical ataxia telangiectasia-mutated (ATM) kinase-mediated DNA damage response, as shown by elevated expression of γ-H2 AX, p-ATM and p-Chk2. This is finally followed by the induction of cell cycle arrest and apoptosis, as shown by the increase of TUNEL-stained cells, caspase activation, PARP cleavage and the increase of bax/bcl-2 ratio. Moreover, Riccardin D induced p53-proficient MCF-7 cells to arrest in G1 phase and p53-deficient MDA-MB-231 cells to arrest in G2/M phase. Overall, these results demonstrate that Riccardin D may inhibit human breast cancer growth through suppression of telomerase activity.
Department of Pharmacology, Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, Jinan, China.
Cui-Cui
CC
Sun
Hui-Min
HM
Xu
Yi
Y
Yuan
Zu-Hua
ZH
Gao
Hong-Xiang
HX
Lou
Xian-Jun
XJ
Qu
D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000627:therapeutic use*; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000188:drug therapy*; D045744:Cell Line, Tumor; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D020287:In Situ Nick-End Labeling; D061986:MCF-7 Cells / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D010647:Phenyl Ethers / Q000627:therapeutic use*; D060888:Real-Time Polymerase Chain Reaction; D013267:Stilbenes / Q000627:therapeutic use*; D019098:Telomerase / Q000037:antagonists & inhibitors*
D000972:Antineoplastic Agents, Phytogenic; D010647:Phenyl Ethers; D013267:Stilbenes; C547185:riccardin D; D019098:Telomerase