title: Metronomic topotecan impedes tumor growth of MYCN-amplified neuroblastoma cells in vitro and in vivo by therapy induced senescence.
abstract: Poor prognosis and frequent relapses are major challenges for patients with high-risk neuroblastoma (NB), especially when tumors show MYCN amplification. High-dose chemotherapy triggers apoptosis, necrosis and senescence, a cellular stress response leading to permanent proliferative arrest and a typical senescence-associated secretome (SASP). SASP components reinforce growth-arrest and act immune-stimulatory, while others are tumor-promoting. We evaluated whether metronomic, i.e. long-term, repetitive low-dose, drug treatment induces senescence in vitro and in vivo. And importantly, by using the secretome as a discriminator for beneficial versus adverse effects of senescence, drugs with a tumor-inhibiting SASP were identified.We demonstrate that metronomic application of chemotherapeutic drugs induces therapy-induced senescence, characterized by cell cycle arrest, p21(WAF/CIP1) up-regulation and DNA double-strand breaks selectively in MYCN-amplified NB. Low-dose topotecan (TPT) was identified as an inducer of a favorable SASP while lacking NFKB1/p50 activation. In contrast, Bromo-deoxy-uridine induced senescent NB-cells secret a tumor-promoting SASP in a NFKB1/p50-dependent manner. Importantly, TPT-treated senescent tumor cells act growth-inhibitory in a dose-dependent manner on non-senescent tumor cells and MYCN expression is significantly reduced in vitro and in vivo. Furthermore, in a mouse xenotransplant-model for MYCN-amplified NB metronomic TPT leads to senescence selectively in tumor cells, complete or partial remission, prolonged survival and a favorable SASP.This new mode-of-action of metronomic TPT treatment, i.e. promoting a tumor-inhibiting type of senescence in MYCN-amplified tumors, is clinically relevant as metronomic regimens are increasingly implemented in therapy protocols of various cancer entities and are considered as a feasible maintenance treatment option with moderate adverse event profiles.
authors.affiliation: CCRI, Chlidren's Cancer Research Institute, Vienna, Austria.
authors.forename: Sabine
authors.initials: S
authors.lastname: Taschner-Mandl
authors.affiliation: CCRI, Chlidren's Cancer Research Institute, Vienna, Austria.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Schwarz
authors.affiliation: CCRI, Chlidren's Cancer Research Institute, Vienna, Austria.
authors.forename: Johanna
authors.initials: J
authors.lastname: Blaha
authors.affiliation: CCRI, Chlidren's Cancer Research Institute, Vienna, Austria.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Kauer
authors.affiliation: CCRI, Chlidren's Cancer Research Institute, Vienna, Austria.
authors.forename: Florian
authors.initials: F
authors.lastname: Kromp
authors.affiliation: CCRI, Chlidren's Cancer Research Institute, Vienna, Austria.
authors.forename: Nelli
authors.initials: N
authors.lastname: Frank
authors.affiliation: CCRI, Chlidren's Cancer Research Institute, Vienna, Austria.
authors.forename: Fikret
authors.initials: F
authors.lastname: Rifatbegovic
authors.affiliation: CCRI, Chlidren's Cancer Research Institute, Vienna, Austria.
authors.forename: Tamara
authors.initials: T
authors.lastname: Weiss
authors.affiliation: CCRI, Chlidren's Cancer Research Institute, Vienna, Austria.|Department of Pediatrics, Medical University of Vienna, Vienna, Austria.
authors.forename: Ruth
authors.initials: R
authors.lastname: Ladenstein
authors.affiliation: Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Hohenegger
authors.affiliation: CCRI, Chlidren's Cancer Research Institute, Vienna, Austria.
authors.forename: Inge M
authors.initials: IM
authors.lastname: Ambros
authors.affiliation: CCRI, Chlidren's Cancer Research Institute, Vienna, Austria.|Department of Pediatrics, Medical University of Vienna, Vienna, Austria.
authors.forename: Peter F
authors.initials: PF
authors.lastname: Ambros
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D016922:Cellular Senescence / Q000187:drug effects*; D005260:Female; D005455:Fluorescent Antibody Technique; D005784:Gene Amplification; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D000071447:N-Myc Proto-Oncogene Protein / Q000235:genetics*; D009447:Neuroblastoma / Q000235:genetics / Q000473:pathology / Q000517:prevention & control*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D059004:Topoisomerase I Inhibitors / Q000494:pharmacology*; D019772:Topotecan / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: C459801:MYCN protein, human; D000071447:N-Myc Proto-Oncogene Protein; D012333:RNA, Messenger; D059004:Topoisomerase I Inhibitors; D019772:Topotecan
keywords: MYCN-amplified neuroblastoma; NFKB1; metronomic; senescence-associated-secretory-phenotype; topotecan