WT1 protein is cleaved by caspase-3 in apoptotic leukemic cells

• Published in: Leukemia & lymphoma Vol. 59; no. 1; pp. 162 - 170
• Main Authors: Ruan, Jichen, Gao, Shenmeng, Yang, Junjun, Li, Haiying, Huang, He, Zheng, Xiaoqun
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 02-01-2018
• Subjects: Amino Acid Sequence; Apoptosis - drug effects; Apoptosis - genetics; Caspase 3 - metabolism; caspase-3; Cell Line, Tumor; cleavage; Gene Expression Regulation, Leukemic; Humans; Leukemia - metabolism; Proteolysis; Recombinant Fusion Proteins; Transcription, Genetic; WT1; WT1 Proteins - chemistry; WT1 Proteins - genetics; WT1 Proteins - metabolism; WT1; cleavage; caspase-3
• ISSN: 1042-8194; 1029-2403
• DOI: 10.1080/10428194.2017.1312368

The aberrant overexpression of Wilms' tumor-1 gene (WT1) plays an important role in blast cell survival and resistance to chemotherapy in acute myeloid leukemia (AML). Here, we found in chemotherapeutic drug etoposide-induced apoptosis, WT1 protein was cleaved into smaller fragment by caspase-3 in leukemic cells. The cleavage was blocked by pan-caspase inhibitor and special caspase-3 inhibitor, suggesting that caspase-3 might cleave WT1 protein. Furthermore, recombinant active caspase-3 cleaved the Flag-WT1 and GST-WT1 proteins in vitro. However, site-directed mutagenesis analyses failed to identify caspase-3-targeted sites in WT1 protein, indicating that caspase-3 cleaved uncommon sites but not classical motifs (DXXD) and non-classical motifs (XXXD). Finally, Eto decreased c-Myc and Bcl-2 expression via reducing the binding of WT1 to the promoter and Eto-induced apoptosis was partially prevented by overexpression of WT1. Collectively, we identify a new substrate for caspase-3 and shed new light on understanding the complicated biology of WT1 in leukemia.