iASPP Is an Antioxidative Factor and Drives Cancer Growth and Drug Resistance by Competing with Nrf2 for Keap1 Binding

Cancer Cell. 2017 Nov 13;32(5):561-573.e6. doi: 10.1016/j.ccell.2017.09.008. Epub 2017 Oct 12.

Abstract

Reactive oxygen species (ROS) have emerged as important signaling molecules that play crucial roles in carcinogenesis and cytotoxic responses. Nrf2 is the master regulator of ROS balance. Thus, uncovering mechanisms of Nrf2 regulation is important for the development of alternative treatment strategies for cancers. Here, we demonstrate that iASPP, a known p53 inhibitor, lowers ROS independently of p53. Mechanistically, iASPP competes with Nrf2 for Keap1 binding via a DLT motif, leading to decreased Nrf2 ubiquitination and increased Nrf2 accumulation, nuclear translocation, and antioxidative transactivation. This iASPP-Keap1-Nrf2 axis promotes cancer growth and drug resistance both in vitro and in vivo. Thus, iASPP is an antioxidative factor and represents a promising target to improve cancer treatment, regardless of p53 status.

Keywords: Keap1; Nrf2; ROS; cancer growth; chemoresistance; iASPP; renal cell carcinoma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antioxidants / metabolism
  • Blotting, Western
  • Cell Line, Tumor
  • Cell Proliferation*
  • Drug Resistance, Neoplasm*
  • HCT116 Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Kelch-Like ECH-Associated Protein 1 / genetics
  • Kelch-Like ECH-Associated Protein 1 / metabolism*
  • NF-E2-Related Factor 2 / genetics
  • NF-E2-Related Factor 2 / metabolism*
  • Neoplasms / genetics
  • Neoplasms / metabolism
  • Neoplasms / pathology
  • Protein Binding
  • RNA Interference
  • Reactive Oxygen Species / metabolism
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism

Substances

  • Antioxidants
  • Intracellular Signaling Peptides and Proteins
  • KEAP1 protein, human
  • Kelch-Like ECH-Associated Protein 1
  • NF-E2-Related Factor 2
  • NFE2L2 protein, human
  • PPP1R13L protein, human
  • Reactive Oxygen Species
  • Repressor Proteins
  • Tumor Suppressor Protein p53