Oral Presentation Advances in Neuroblastoma Research Congress 2016

Long term, continuous exposure to panobinostat induces terminal differentiation and long term survival in the TH-NMYC neuroblastoma mouse model (#48)

Kelly Waldeck 1 , Carleen Cullinane 1 , Kerry Ardley 1 , Jake Shortt 2 3 4 , Ben Martin 2 , Richard Tothill 1 , Jason Li 2 , Ricky W Johnstone 2 3 , Grant A McArthur 3 5 6 , Rod J Hicks 1 3 , Paul J Wood 1 7 8
  1. Translational Research Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
  2. Gene Regulation Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
  3. Sir Peter MacCallum Department of Oncology, University Of Melbourne, Melbourne, Victoria, Australia
  4. School of Clinical Sciences at Monash Health, Monash University, Clayton, Victoria, Australia
  5. Molecular Oncology Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
  6. Department of Medicine, St. Vincents Hospital, Melbourne, Victoria, Australia
  7. Department of Paediatrics, Monash University, Clayton, Victoria, Australia
  8. Childrens Cancer Centre, Monash Health, Clayton, Victoria, Australia

Background/Aims: Deregulated acetylation of histones plays a key role in the pathogenesis of hematological as well as solid tumors by changing the chromatin structure and consequently altering transcription of genes involved in cell cycle control, differentiation and apoptosis. The aim of this study was to investigate the impact of panobinostat dosing on the TH-NMYC mouse model for neuroblastoma, with emphasis on apoptosis, NMYC expression and differentiation.

 

Methods: Homozygous TH-MYCN transgenic mice underwent abdominal ultrasounds (US) until neuroblastomas of 50mm3- 200 mm3 were detected. Mice were randomized to receive panobinostat, daily for 3 or 9 weeks, or vehicle. Tumour volume was monitored by serial US. Upon tumor development, or at 100 days following cessation of panobinostat, tumors were harvested for immunohistochemical (IHC) analysis of differentiation markers. For short-term experiments, tumors were harvested after 24hr for western blot and IHC analysis of markers of apoptosis and HDAC inhibition. RNA-seq analysis was performed on tumors harvested at baseline and at 24hr post panobinostat treatment. Gene set enrichment, and pathway analysis was then performed to investigate changes in the expression of genes associated with apoptosis, differentiation and NMYC expression.

 

Results: Treatment with panobinostat significantly improved survival with 3 weeks of treatment increasing mean survival from 7 to 68 days (p<0.0001), while 9 weeks of panobinostat treatment resulted in 88.9% of mice alive 100 days post withdrawal of drug (p<0.0001 compared to 3 week and vehicle groups). Panobinostat induced rapid tumour regression and significant caspase-dependent apoptosis. Panobinostat also induced differentiation of neuroblastomas into benign ganglioneuromas as evidenced by H&E and IHC analysis of the differentiation markers S100, NSE and SSTR2. Correspondingly tumors had reduced expression of NMYC. RNA-seq confirmed tumors up-regulated gene pathways associated with apoptosis and differentiation, and down-regulation of NMYC associated pathways. 

 

Conclusions: Treatment of TH-NMYC mice with panobinostat significantly improved survival and reduced tumour burden, supporting the further evaluation of panobinostat as a treatment option for high-risk neuroblastoma patients.