Poster Presentation 28th Lorne Cancer Conference 2016

Effects of EphB4 Receptor Expression on Colorectal Cancer Cell Behaviour, Tumour Growth and Vascularisation (#173)

Elif Kadife 1 2 , Thomas, M.B. Ware 3 , Rodney, B. Luwor 3 , Steven, T.F. Chan 2 4 , Kulmira Nurgali 1 2 , Paul, V. Senior 2 4
  1. Centre for Chronic Disease, College of Health and Biomedicine, Victoria University, Melbourne, VIC, Australia
  2. Western Centre for Health Research and Education, Sunshine Hospital, Melbourne, VIC, Australia
  3. Department of Surgery, The University of Melbourne, The Royal Melbourne Hospital, Parkville, VIC, Australia
  4. North West Academic Centre, The University of Melbourne, Melbourne, VIC, Australia

Colorectal cancer (CRC) is one of the most common causes of cancer related deaths worldwide. Molecular targets are being investigated in order to improve the efficacy of current treatments and reduce CRC recurrence rates in patients. Increased expression of the tryrosine kinase receptor EphB4 receptor occurs in several cancer types and targeting this receptor has shown to be beneficial. However, studies on the role of EphB4 receptor in CRC have yielded contradictory results.

The aim of this study was to investigate the influence of EphB4 expression levels on CRC cell behaviour and its contribution to tumour growth and vascularisation. SW480 and LIM2405 human CRC cell lines were transfected with EphB4 expression vectors. CRISPR-Cas9 was used to knock out EphB4 expression in HT29 CRC cell line. Modified clones were compared to empty vector and wild-type controls. Proliferation and migration assays were conducted in vitro and subcutaneous xenografts of CRC were analysed in vivo.

EphB4 expression enhanced migratory abilities of SW480, LIM2405 and HT29 CRC cell lines. Only the LIM2405 cell line showed a significant effect on proliferation in vitro where EphB4 expression increased cell growth.

Subcutaneous xenograft tumours derived from high EphB4 expressing SW480 cells had more extensive vascularisation and less central necrosis than seen in those derived from wild-type and empty vector SW480 cells. Tumours derived from high EphB4 expressing cells yielded homogenous masses densely packed with human cancer cells that containing less mouse-derived stroma. The composition of tumours derived from high EphB4 expressing cells suggest limited cellular intermingling between cancer cells and surrounding tissue, similar to that seen in EphB2 expressing CRC, where interaction with stromally expressed ephrinB1 ligand restricts cell migration. Thus EphB4 expression could constrain local invasion, however, the presence of more highly developed vasculature within the tumours may increase the propensity to metastasize through blood vessels.