Poster Presentation 6th Australian Health and Medical Research Congress 2012

VEGF expression in colorectal tumours with microsatellite instability and its association with BRAF mutation status (#307)

Suja Pillai 1 , Vinod Gopalan 1 , Kristina Balaba 1 , Sze Yan Chen 1 , Ali Salajegheh 1 , Melissa Y-Y Leung 1 , Robert A Smith 1 , Alfred K-Y Lam 1
  1. School of Medicine and Griffith Health Institute, Griffith University, Gold Coast, Queensland, Australia

Colorectal cancers with microsatellite instability (MSI) follow a specific pathway to angiogenesis. Previous studies have reported low frequency of VEGF expression in MSI high (MSI-H) tumours and in turn explain the reasons for reduced aggressiveness and better prognosis in MSI-H colorectal tumours. Also, BRAF mediated activation of specific signaling pathways plays a vital role in the enhancement of VEGF expression in human cancers. In this study we aimed to screen VEGF-A protein expression in MSI-H colorectal tumours with regard to BRAF mutation status. Thirty six MSI-H colorectal cancers were recruited and BRAF mutation (V600E+) status was assessed for all the cases. Among these cases 31 were positive for BRAF mutation and 5 colorectal cancers were negative for the BRAF mutation (wild type). Immunohistochemistry was performed to assess the expression of VEGF-A protein in these colorectal cancers. Both intensity and percentages of the VEGF protein staining were evaluated. All colorectal cancers showed positive staining for VEGF-A protein. In addition, VEGF-A protein did not show any change in its expression (either by intensity or percentage) in MSI-H with different BRAF mutation status. To conclude, this is the first study reporting the status of VEGF expression in MSI-H colorectal tumours with respect to BRAF mutation status. These results suggest that BRAF wild type MSI-H colorectal tumours may have VEGF activity similar to that of BRAF mutated MSI-H tumours.