NDRG2 Sensitizes Myeloid Leukemia to Arsenic Trioxide via GSK3β-NDRG2-PP2A Complex Formation

Area of Science:

• Oncology
• Molecular Biology
• Biochemistry

Background:

• N-Myc downstream-regulated gene 2 (NDRG2) is recognized as a tumor suppressor with anti-metastatic and anti-proliferative properties.
• The precise role of NDRG2 in modulating anticancer drug sensitivity and its underlying molecular mechanisms remain incompletely understood.

Purpose of the Study:

• To elucidate the mechanism by which NDRG2 influences sensitization to arsenic trioxide (As2O3) in the U937 cell line.
• To investigate the role of NDRG2 in the degradation of Mcl-1 and activation of glycogen synthase kinase 3β (GSK3β) in response to As2O3.

Main Methods:

• Overexpression of NDRG2 in U937 cells (U937-NDRG2) and comparison with mock control cells (U937-Mock).
• Assessment of As2O3 sensitivity, Mcl-1 degradation, and GSK3β phosphorylation status.
• Investigation of the interaction between NDRG2, GSK3β, and protein phosphatase 2A (PP2A) using a C-terminal deletion mutant of NDRG2.

Main Results:

• U937-NDRG2 cells exhibited significantly higher sensitivity to As2O3 compared to U937-Mock cells.
• NDRG2 overexpression led to Mcl-1 degradation via GSK3β activation, evidenced by reduced inhibitory phosphorylation of GSK3β at S9.
• NDRG2 facilitated the interaction between GSK3β and PP2A, promoting GSK3β dephosphorylation by PP2A. A mutant NDRG2 lacking PP2A interaction failed to induce these effects.

Conclusions:

• NDRG2 functions as an adaptor protein that bridges GSK3β and PP2A.
• NDRG2-mediated dephosphorylation of GSK3β by PP2A activates GSK3β, enhancing As2O3 sensitivity in U937 cells.
• These findings reveal a novel mechanism for NDRG2 in modulating drug response and offer potential therapeutic insights.