Bortezomib potentiates antitumor activity of Mitoxantrone through dampening Wnt/β-catenin signaling pathway in prostate cancel cells

Background: Bortezomib (BZM), alone or in combination with other chemotherapies, has displayed strong anticancer effects in several cancers. The efficacy of the combination of BZM and mitoxantrone (MTX) in treating prostate cancer remains unknown. Methods: Anticancer effects of combination of BZM and MTX were determined by apoptosis and proliferation assay in vivo and in vitro. Expression of β-catenin and its target genes were characterized by western blot and Real-time PCR. Results: BZM significantly enhanced MTX-induced antiproliferation in vivo and in vitro. Mice administered a combination of BZM and MTX displayed attenuated tumor growth and prolonged survival. BZM significantly attenuated MTX-induced apoptosis. Moreover, the combination of BZM and MTX contributed to inhibition of the Wnt/β-catenin signaling pathway compared to monotherapy. Conclusions: This study demonstrates that BZM enhances MTX-induced anti-tumor effects by inhibiting the Wnt/β-catenin signaling pathway in prostate cancer cells.