title: 5k, a novel β-O-demethyl-epipodophyllotoxin analogue, inhibits the proliferation of cancer cells in vitro and in vivo via the induction of G2 arrest and apoptosis.
abstract: Etoposide (VP-16), a topoisomerase II (Topo II) inhibitor, has been widely used to treat malignancies. Its clinical application, however, has been hindered by the rise of acquired multidrug resistance (MDR). Here, we report that 4β-{[4-(pyrrolidin-1-ylmethyl)phenyl]amino}-4'-O-Demethyl-4-Epipodophyllotoxin (5k), a novel β-O-demethyl-epipodophyllotoxin analogue, possesses higher antitumor activity than its parent compound (VP-16) in a panel of various human tumor cell lines. More importantly, it was also effective against MDR cells both in vitro and in vivo. Using a KB/VCR MDR tumor xenograft model that overexpresses P-gp, 5k (2.5 mg/kg) exhibited a 2.4-fold higher growth inhibition rate versus VP-16 (5 mg/kg). In contrast, 5k and VP-16 displayed similar antitumor activities in a KB tumor xenograft model. Molecular and cellular mechanism studies revealed that 5k targeted Topo II by trapping DNA-Topo II cleavage complexes that could directly cause DNA damage. There were two distinct cellular responses to DNA damage elicited by the treatment with 5k: at low concentrations (20-80 nM), mitotic entry was arrested through the suppression of the activity of Cyclin B1/Cdc 2 complexes via the ATM/ATR signaling pathway; at high concentrations (1.25-5.00 μM), 5k-induced apoptotic signaling was mediated by the mitochondrial death pathways. Collectively, these data demonstrate the potential value of 5k as an antitumor drug candidate that should be further developed.
authors.affiliation: Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Room 113, Building of College of Pharmaceutical Sciences, Zijin'gang campus, Hangzhou, People's Republic of China.
authors.forename: Danqing
authors.initials: D
authors.lastname: Xu
authors.forename: Ji
authors.initials: J
authors.lastname: Cao
authors.forename: Shijing
authors.initials: S
authors.lastname: Qian
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.forename: Chunqi
authors.initials: C
authors.lastname: Hu
authors.forename: Qinjie
authors.initials: Q
authors.lastname: Weng
authors.forename: Jianshu
authors.initials: J
authors.lastname: Lou
authors.forename: Difeng
authors.initials: D
authors.lastname: Zhu
authors.forename: Hong
authors.initials: H
authors.lastname: Zhu
authors.forename: Yongzhou
authors.initials: Y
authors.lastname: Hu
authors.forename: Qiaojun
authors.initials: Q
authors.lastname: He
authors.forename: Bo
authors.initials: B
authors.lastname: Yang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002110:Caffeine / Q000494:pharmacology; D020169:Caspases / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004249:DNA Damage; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004273:DNA, Neoplasm / Q000378:metabolism; D004354:Drug Screening Assays, Antitumor; D005260:Female; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects*; D017405:Herpes Simplex Virus Protein Vmw65 / Q000494:pharmacology; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009369:Neoplasms / Q000201:enzymology / Q000473:pathology*; D011034:Podophyllotoxin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D059005:Topoisomerase II Inhibitors / Q000494:pharmacology
chemical_list: C568782:4-((4-(pyrrolidin-1-ylmethyl)phenyl)amino)-4'-O-demethyl-4-epipodophyllotoxin; D018797:Cell Cycle Proteins; D004273:DNA, Neoplasm; D017405:Herpes Simplex Virus Protein Vmw65; D019253:Proto-Oncogene Proteins c-bcl-2; D059005:Topoisomerase II Inhibitors; D002110:Caffeine; D020169:Caspases; D004250:DNA Topoisomerases, Type II; D011034:Podophyllotoxin