c-MYC overexpression overrides TAK1 dependency in efficient tumorigenicity of AKT-transformed cells

• TAK1 inhibition attenuates the tumor growth of the AKT-transformed cells in vivo.
• TAK1 regulates the tumorigenicity of AKT-transformed cells involving FADD-independent mechanisms in vivo.
• TAK1 inhibition decreases anchorage-independent cell growth of AKT-transformed cells.
• TAK1 dependence for efficient tumorigenesis of AKT-transformed cells is alleviated by c-Myc overexpression.

Transforming growth factor activated kinase 1 (TAK1) provides prosurvival signals in various types of cells, and emerging evidence indicates that targeting TAK1 is a promising means to eliminate certain types of cancer cells. Here, we show that TAK1 is required for efficient tumorigenicity of AKT-transformed cells. TAK1 inhibition accelerates cell apoptosis of AKT-transformed cells in anchorage-independent cell growth accompanying by the downregulation of Mcl-1 and Bcl-2 expression. On the contrary, the tumorigenicity of c-Myc-transformed cells is not significantly affected by TAK1 inhibition. Moreover, AKT-transformed cells with c-Myc overexpression tolerate TAK1 inhibition in anchorage-independent growth and tumorigenicity in vivo. Together, our results provide evidence that TAK1-dependency in the tumorigenicity of AKT-transformed cells can be alleviated by c-Myc overexpression. These findings suggest that dual-targeting TAK1 and c-Myc might be a rational therapeutic strategy for treatment of certain types of cancer.