SPOP is essential for DNA-protein cross-link repair in prostate cancer cells: SPOP-dependent removal of topoisomerase 2A from the topoisomerase 2A-DNA cleavage complex

Mol Biol Cell. 2020 Mar 15;31(6):478-490. doi: 10.1091/mbc.E19-08-0456. Epub 2020 Jan 22.

Abstract

SPOP, speckle-type POZ protein is a substrate adaptor protein of the Cullin-3/RING ubiquitin E3 complex. The spop gene is the most commonly point mutated in human primary prostate cancers, but the pathological contribution of the SPOP mutations remains unclear. In this study, we investigated several known factors that are critical in the DNA--protein cross-link repair process. The depletion of SPOP or overexpression of a prostate cancer-associated SPOP mutant, F133V, in androgen receptor-positive prostate cancer cells increased the amount of topoisomerase 2A (TOP2A) in the nuclei together with the increased amount of γH2AX, an indication of DNA breaks. Tyrosyl-DNA phosphodiesterases (TDPs) and an endo/exonuclease MRE11 are enzymes that liberate TOP2A from the TOP2A-DNA cleavage complex, and thus is essential for the completion of the DNA repair process. We found that the amount of TDP1 and TDP2 was decreased in SPOP-depleted cells, and that of TDP2 and MRE11 was decreased in F133V-overexpressing cells. These results suggest that the F133V mutant exerts dominant-negative and gain-of-function effects in down-regulation of TDP2 and MRE11, respectively. We conclude that SPOP is involved in the DNA-protein cross-link repair process through the elimination of TOP2A from the TOP2A cleavage complex, which may contribute to the genome stability.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Death / drug effects
  • Cell Nucleus / drug effects
  • Cell Nucleus / metabolism
  • DNA Cleavage*
  • DNA Replication / drug effects
  • DNA Topoisomerases, Type II / metabolism*
  • DNA, Neoplasm / metabolism*
  • Etoposide / pharmacology
  • Histones / metabolism
  • Humans
  • Hydroxyurea / pharmacology
  • Male
  • Models, Biological
  • Mutation / genetics
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Poly-ADP-Ribose Binding Proteins / metabolism*
  • Prostatic Neoplasms / metabolism*
  • Prostatic Neoplasms / pathology
  • Receptors, Androgen / metabolism
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Topoisomerase Inhibitors / pharmacology

Substances

  • DNA, Neoplasm
  • H2AX protein, human
  • Histones
  • Nuclear Proteins
  • Poly-ADP-Ribose Binding Proteins
  • Receptors, Androgen
  • Repressor Proteins
  • SPOP protein, human
  • Topoisomerase Inhibitors
  • Etoposide
  • DNA Topoisomerases, Type II
  • TOP2A protein, human
  • Hydroxyurea