Poster Presentation Australian Society for Medical Research Annual Scientific Meeting 2016

In-vitro and in-vivo confirmation of oncogenic properties of GAEC1 in colon cancer (#108)

S M Riajul Wahab 1 , Vinod Gopalan 1 , Md Farhadul Islam 1 , Alfred Lam 1
  1. Griffith University, Southport, Gold Coast, QLD, Australia

Introduction: GAEC1 (Gene amplified in esophageal cancer 1) is previously reported to have oncogenic properties in esophageal squamous cell carcinoma. In our previous work we have reported frequent amplification and overexpression of GAEC1 in colorectal cancer tissues. In this study, we aimed to investigate the oncogenic property of GAEC1 and the underlying cellular and molecular mechanism in colon cancer cells by in-vitro and in-vivo experiments.

Method: Transient knockdown of GAEC1 with a siRNA was performed and various downstream assays were performed such as migration, clonogenic and apoptotic assays. Flow cytometry was used for cell cycle analysis and cell proliferation assay has been done using cell counting kit-8. Western blot and immunofluorescence analysis was used to determine the expression of different downstream proteins. To perform tumor xenograft assay, the severely combined immunodeficient (SCID) mice (4 groups, 6 in each group) were injected subcutaneously with GAEC1 shRNA and control shRNA transfected (stable) SW480 and SW48 colon cancer cells.

Result: Knockdown of GAEC-1 significantly reduced the clonogenic and migration capacity of colon cancer cells. Knockdown of GAEC1 increased the apoptosis and led to the G2/M phase arrest of colon cancer cells. Furthermore, downregulation of GAEC1 in SW480 and SW48 colon cancer cells reduced the anti-apoptotic protein Bcl-2, KRAS oncoprotein and increased the p53 tumor suppressor protein. In addition, our in-vivo data demonstrate that loss of GAEC1 inhibits the tumor formation in xenograft model.

Conclusion: Absence of tumor formation in xenograft model in-vivo and suppression of various growth assays in-vitro followed by GAEC1 knockdown confirms its oncogenic roles in colon cancer cells.