Runx2 silencing sensitized human renal cell carcinoma cells to ABT-737 apoptosis

Abstract

The prognostic value of Runt-related transcription factor 2 (Runx2) and its involvement in cell growth and motility have been reported in patients diagnosed with renal cell carcinoma (RCC). Since Runx2 may have the potential to be a target for the purpose of antitumor intervention, there is an urgent need to gain insight into its oncogenic properties. Using human 786-O, Caki-1 and ACHN RCC cells as models, the silencing of cellular Runx2 expression brought about a reduction in cyclin D1 and β-catenin expression, cell growth and migration without any significant cell death. Runx2-silenced cells turned into apoptosis vulnerable in the presence of ABT-737, a BH3 mimetic Bcl-2 inhibitor. Data from biochemical and molecular studies have revealed a positive correlation between Runx2 expression and Akt phosphorylation, Mcl-1 expression, and fibronectin expression. Results of genetic silencing studies have indicated the potential involvement of Mcl-1 and fibronectin in the decision of RCC cell ABT-737 resistance and sensitivity. The regulatory roles of the PI3K/Akt axis in the expression of Mcl-1 and fibronectin were suggested by means of the results taken from experiments involving pharmacological study of the PI3K/Akt. Since overexpression and prognostic roles of Runx2, activated Akt, Mcl-1, fibronectin, cyclin D1, and β-catenin have been revealed in RCC, it is important to explore the precise mechanisms underlying Runx2 oncogenic effects. Although the linking details between Runx2 and PI3K/Akt have yet to be identified, our findings suggest that Mcl-1 and fibronectin are downstream effectors of Runx2 via a regulatory axis of the PI3K/Akt and their promotion of cell growth, migration, and ABT-737 resistance in RCC cells.