Inhibiting β-Catenin by β-Carboline-Type MDM2 Inhibitor for Pancreatic Cancer Therapy

• Main Authors: Jiang-Jiang Qin (Author), Wei Wang (Author), Xin Li (Author), Hemantkumar Deokar (Author), John K. Buolamwini (Author), Ruiwen Zhang (Author)
• Format: Book
• Published: Frontiers Media S.A., 2018-01-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 1663-9812; 10.3389/fphar.2018.00005
• Keywords: β-carboline; β-catenin; MDM2; p53; pancreatic cancer; protein degradation; Therapeutics. Pharmacology; RM1-950
• Source: Frontiers in Pharmacology, Vol 9 (2018)

The β-catenin and MDM2 oncoproteins are overexpressed and constitutively activated in human pancreatic cancer and contribute to its initiation, progression, and metastasis. The Wnt/β-catenin signaling pathway strongly interacts with the MDM2-p53 signaling pathway, accelerating the tumorigenesis and its development. Therefore, therapies inhibiting both β-catenin and MDM2 are suggested to be ideal treatments for patients with advanced pancreatic cancer. We have recently identified a novel class of β-carboline compounds as the specific and potent MDM2 inhibitors, including a lead compound SP141. In the present study, we utilized SP141 as an exemplary β-carboline compound to characterize β-catenin as a molecular target of the β-carboline compounds and to demonstrate an important role of β-catenin in the anticancer activity of β-carboline. We found that the silencing of either β-catenin or MDM2 largely reduced the anticancer activity of SP141 while the double silencing of both genes almost completely blocked SP141's activity. SP141 directly bound to β-catenin and inhibited its expression and activity in pancreatic cancer cells in vitro and in vivo. The inhibitory effects of SP141 on β-catenin were mediated by the ubiquitin-proteasome system in an MDM2-independent manner. In conclusion, these results suggest that SP141 exerts its anticancer activity by dually inhibiting β-catenin and MDM2. We envision that β-carboline derivatives can be developed as promising dual inhibitors of β-catenin and MDM2 for the treatment of advanced pancreatic cancer.