Wnt signaling promotes oncogenic transformation by inhibiting c-Myc–induced apoptosis

Z You, D Saims, S Chen, Z Zhang… - The Journal of cell …, 2002 - rupress.org
Z You, D Saims, S Chen, Z Zhang, DC Guttridge, K Guan, OA MacDougald, AMC Brown
The Journal of cell biology, 2002rupress.org
Aberrant activation of the Wnt/β-catenin signaling pathway is associated with numerous
human cancers and often correlates with the overexpression or amplification of the c-myc
oncogene. Paradoxical to the cellular transformation potential of c-Myc is its ability to also
induce apoptosis. Using an inducible c-MycER expression system, we found that Wnt/β-
catenin signaling suppressed apoptosis by inhibiting c-Myc–induced release of cytochrome
c and caspase activation. Both cyclooxygenase 2 and WISP-1 were identified as effectors of …
Aberrant activation of the Wnt/β-catenin signaling pathway is associated with numerous human cancers and often correlates with the overexpression or amplification of the c-myc oncogene. Paradoxical to the cellular transformation potential of c-Myc is its ability to also induce apoptosis. Using an inducible c-MycER expression system, we found that Wnt/β-catenin signaling suppressed apoptosis by inhibiting c-Myc–induced release of cytochrome c and caspase activation. Both cyclooxygenase 2 and WISP-1 were identified as effectors of the Wnt-mediated antiapoptotic signal. Soft agar assays showed that neither c-Myc nor Wnt-1 alone was sufficient to induce cellular transformation, but that Wnt and c-Myc coordinated in inducing transformation. Furthermore, coexpression of Wnt-1 and c-Myc induced high-frequency and rapid tumor growth in nude mice. Extensive apoptotic bodies were characteristic of c-Myc–induced tumors, but not tumors induced by coactivation of c-Myc and Wnt-1, indicating that the antiapoptotic function of Wnt-1 plays a critical role in the synergetic action between c-Myc and Wnt-1. These results elucidate the molecular mechanisms by which Wnt/β-catenin inhibits apoptosis and provide new insight into Wnt signaling-mediated oncogenesis.
rupress.org