title: Cytotoxicity and cell death mechanisms induced by the polyamine-vectorized anti-cancer drug F14512 targeting topoisomerase II.
abstract: The polyamines transport system (PTS) is usually enhanced in cancer cells and can be exploited to deliver anticancer drugs. The spermine-conjugated epipodophyllotoxin derivative F14512 is a topoisomerase II poison that exploits the PTS to target preferentially tumor cells. F14512 has been characterized as a potent anticancer drug candidate and is currently in phase 1 clinical trials. Here we have analyzed the mechanisms of cell death induced by F14512, compared to the parent drug etoposide lacking the polyamine tail. F14512 proved to be >30-fold more cytotoxic than etoposide against A549 non-small cell lung cancer cells and triggers less but unrecoverable DNA damages. The cytotoxic action of F14512 is extremely rapid (within 3 h) and does not lead to a marked accumulation in the S-phase of the cell cycle, unlike etoposide. Interestingly, A549 cells treated with F14512 were less prone to undergo apoptosis (neither caspases-dependent nor caspases-independent pathways) or autophagy but preferentially entered into senescence. Drug-induced senescence was characterized qualitatively and quantitatively by an increased β-galactosidase activity, both by cytochemical staining and by flow cytometry. A morphological analysis by electron microscopy revealed the presence of numerous multi-lamellar and vesicular bodies and large electron-lucent (methuosis-like) vacuoles in F14512-treated cell samples. The mechanism of drug-induced cell death is thus distinct for F14512 compared to etoposide, and this difference may account for their distinct pharmacological profiles and the markedly superior activity of F14512 in vivo. This study suggests that senescence markers should be considered as potential pharmacodynamic biomarkers of F14512 antitumor activity.
authors.affiliation: Centre de Recherche en Oncologie Expérimentale, Institut de Recherche Pierre Fabre, Centre de Recherche et Développement, 3 Avenue Hubert Curien, BP 13562, 31035 Toulouse cedex 1, France. viviane.brel@pierre-fabre.com
authors.forename: Viviane
authors.initials: V
authors.lastname: Brel
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Annereau
authors.forename: Stéphane
authors.initials: S
authors.lastname: Vispé
authors.forename: Anna
authors.initials: A
authors.lastname: Kruczynski
authors.forename: Christian
authors.initials: C
authors.lastname: Bailly
authors.forename: Nicolas
authors.initials: N
authors.lastname: Guilbaud
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects; D002453:Cell Cycle; D045744:Cell Line, Tumor; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D005047:Etoposide / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D015394:Molecular Structure; D011034:Podophyllotoxin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D011073:Polyamines / Q000378:metabolism*; D059005:Topoisomerase II Inhibitors / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; C534191:F14512; D011073:Polyamines; D059005:Topoisomerase II Inhibitors; D005047:Etoposide; D004250:DNA Topoisomerases, Type II; D011034:Podophyllotoxin