Poster Presentation Advances in Neuroblastoma Research Congress 2016

Stathmin mediates neuroblastoma metastasis in a tubulin-independent manner via RhoA/ROCK signalling and enhanced transendothelial migration (#360)

Maria Kavallaris 1 2 , Christopher M Fife 1 , Sharon M Sagnella 1 , Frances L Byrne 3 , Yvonne YC Yeap 4 , Dominic CH Ng 4 , Tom P Davis 5 , Joshua A McCarroll 1 2
  1. Children's Cancer Institute Australia, Randwick, NSW, Australia
  2. Australian Centre for Nanomedicine, Randwick, NSW, Australia
  3. Biotechnology and Biomolecular Sciences, UNSW Australia, Sydney, NSW
  4. School of Biomedical Science, University of Queensland, Brisbane, QLD
  5. ARC Centre for Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Vic

Neuroblastoma patients frequently present with aggressive metastatic disease and the 5-year survival rates for these children remains poor. Metastasis involves remodelling of the microtubule and actin cytoskeletons. The microtubule destabilizing protein, stathmin, has recently been shown to mediate neuroblastoma metastasis1, and we sought to investigate how stathmin contributes to the metastatic process and potential mechanism(s) by which it exerts these effects. Stathmin suppression significantly reduced neuroblastoma cell invasion of embedded 3D tumour spheroids into an extracellular matrix. Furthermore, stathmin was shown to play an important role in transendothelial migration in two independent neuroblastoma cell lines in vitro. Stathmin’s role in transendothelial migration in neuroblastoma cells was mediated by ROCK signalling, a key regulator of cell migration. Suppression of stathmin expression in neuroblastoma cells significantly increased the activation of the key upstream regulator of ROCK, RhoA small GTPase, suggesting that stathmin regulates this key cytoskeletal signalling pathway. To establish whether the effects on migration was tubulin dependent or independent we re-expressed either wild-type or a phospho-mimetic stathmin mutant (4E) that is defective in tubulin-binding in the stathmin shRNA-expressing cells.  Notably, re-expression of either wild-type or a phospho-mimetic stathmin mutant restored cell migration and transendothelial migration back to control levels indicating that stathmin may regulate these processes independent of its role in tubulin binding. Furthermore, effects of stathmin suppression on in vivo transendothelial migration of neuroblastoma significantly reduced whole body, lung, kidney and liver metastases in a tail-vein delivery experimental metastases mouse model. In conclusion, stathmin plays a role in neuroblastoma via regulation of RhoA/ROCK signalling which in turn affects cell migration, invasion, transendothelial migration and consequently, metastasis. These findings highlight the importance of stathmin to the metastatic process and its potential as a therapeutic target for the treatment of neuroblastoma.

1          Byrne FA,  et al. Oncogene 2014; 33: 882-890.