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

Leuk Lymphoma. 2018 Jan;59(1):162-170. doi: 10.1080/10428194.2017.1312368. Epub 2017 Apr 10.

Abstract

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.

Keywords: WT1; caspase-3; cleavage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Apoptosis* / drug effects
  • Apoptosis* / genetics
  • Caspase 3 / metabolism*
  • Cell Line, Tumor
  • Gene Expression Regulation, Leukemic
  • Humans
  • Leukemia / metabolism*
  • Proteolysis
  • Recombinant Fusion Proteins
  • Transcription, Genetic
  • WT1 Proteins / chemistry
  • WT1 Proteins / genetics
  • WT1 Proteins / metabolism*

Substances

  • Recombinant Fusion Proteins
  • WT1 Proteins
  • Caspase 3