Metronomic topotecan impedes tumor growth of MYCN-amplified neuroblastoma cells in vitro and in vivo by therapy induced senescence

Oncotarget. 2016 Jan 19;7(3):3571-86. doi: 10.18632/oncotarget.6527.


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.

Keywords: MYCN-amplified neuroblastoma; NFKB1; metronomic; senescence-associated-secretory-phenotype; topotecan.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Blotting, Western
  • Cell Cycle / drug effects
  • Cell Proliferation / drug effects
  • Cellular Senescence / drug effects*
  • Female
  • Fluorescent Antibody Technique
  • Gene Amplification*
  • Humans
  • In Vitro Techniques
  • Mice
  • N-Myc Proto-Oncogene Protein / genetics*
  • Neuroblastoma / genetics
  • Neuroblastoma / pathology
  • Neuroblastoma / prevention & control*
  • RNA, Messenger / genetics
  • Real-Time Polymerase Chain Reaction
  • Reverse Transcriptase Polymerase Chain Reaction
  • Topoisomerase I Inhibitors / pharmacology*
  • Topotecan / pharmacology*
  • Tumor Cells, Cultured
  • Xenograft Model Antitumor Assays


  • MYCN protein, human
  • N-Myc Proto-Oncogene Protein
  • RNA, Messenger
  • Topoisomerase I Inhibitors
  • Topotecan