Interdependent genotoxic mechanisms of monomethylarsonous acid

Role of ROS-induced DNA damage and poly(ADP-ribose) polymerase-1 inhibition in the malignant transformation of urothelial cells

Shawn M. Wnek, Christopher L. Kuhlman, Jeannie M. Camarillo, Matthew K. Medeiros, Ke J. Liu, Serrine Lau, A Jay Gandolfi

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Exposure of human bladder urothelial cells (UROtsa) to 50nM of the arsenic metabolite, monomethylarsonous acid (MMA III), for 12weeks results in irreversible malignant transformation. The ability of continuous, low-level MMA III exposure to cause an increase in genotoxic potential by inhibiting repair processes necessary to maintain genomic stability is unknown. Following genomic insult within cellular systems poly(ADP-ribose) polymerase-1 (PARP-1), a zinc finger protein, is rapidly activated and recruited to sites of DNA strand breaks. When UROtsa cells are continuously exposed to 50nM MMA III, PARP-1 activity does not increase despite the increase in MMA III-induced DNA single-strand breaks through 12weeks of exposure. When UROtsa cells are removed from continuous MMA III exposure (2weeks), PARP-1 activity increases coinciding with a subsequent decrease in DNA damage levels. Paradoxically, PARP-1 mRNA expression and protein levels are elevated in the presence of continuous MMA III indicating a possible mechanism to compensate for the inhibition of PARP-1 activity in the presence of MMA III. The zinc finger domains of PARP-1 contain vicinal sulfhydryl groups which may act as a potential site for MMA III to bind, displace zinc ion, and render PARP-1 inactive. Mass spectrometry analysis demonstrates the ability of MMA III to bind a synthetic peptide representing the zinc-finger domain of PARP-1, and displace zinc from the peptide in a dose-dependent manner. In the presence of continuous MMA III exposure, continuous 4-week zinc supplementation restored PARP-1 activity levels and reduced the genotoxicity associated with MMA III. Zinc supplementation did not produce an overall increase in PARP-1 protein levels, decrease the levels of MMA III-induced reactive oxygen species, or alter Cu-Zn superoxide dismutase levels. Overall, these results present two potential interdependent mechanisms in which MMA III may increase the susceptibility of UROtsa cells to genotoxic insult and/or malignant transformation: elevated levels of MMA III-induced DNA damage through the production of reactive oxygen species, and the direct MMA III-induced inhibition of PARP-1.

Original languageEnglish (US)
Pages (from-to)1-13
Number of pages13
JournalToxicology and Applied Pharmacology
Volume257
Issue number1
DOIs
StatePublished - Nov 15 2011

Fingerprint

Poly(ADP-ribose) Polymerases
DNA Damage
Cells
DNA
Zinc
Zinc Fingers
monomethylarsonous acid
Poly (ADP-Ribose) Polymerase-1
Reactive Oxygen Species
Single-Stranded DNA Breaks
Peptides
Proteins
DNA Breaks
Genomic Instability
Arsenic
Metabolites

Keywords

  • Arsenic
  • Bladder cancer
  • Genotoxicity
  • Monomethylarsonous acid
  • Poly(ADP-ribose) polymerase-1
  • UROtsa

ASJC Scopus subject areas

  • Pharmacology
  • Toxicology

Cite this

Interdependent genotoxic mechanisms of monomethylarsonous acid : Role of ROS-induced DNA damage and poly(ADP-ribose) polymerase-1 inhibition in the malignant transformation of urothelial cells. / Wnek, Shawn M.; Kuhlman, Christopher L.; Camarillo, Jeannie M.; Medeiros, Matthew K.; Liu, Ke J.; Lau, Serrine; Gandolfi, A Jay.

In: Toxicology and Applied Pharmacology, Vol. 257, No. 1, 15.11.2011, p. 1-13.

Research output: Contribution to journalArticle

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