Genes & Nutrition

, Volume 7, Issue 2, pp 139–154

Zinc deficiency or excess within the physiological range increases genome instability and cytotoxicity, respectively, in human oral keratinocyte cells

  • Razinah Sharif
  • Philip Thomas
  • Peter Zalewski
  • Michael Fenech
Research Paper

DOI: 10.1007/s12263-011-0248-4

Cite this article as:
Sharif, R., Thomas, P., Zalewski, P. et al. Genes Nutr (2012) 7: 139. doi:10.1007/s12263-011-0248-4

Abstract

Zinc (Zn) is an essential component of Zn-finger proteins and acts as a cofactor for enzymes required for cellular metabolism and in the maintenance of DNA integrity. The study investigated the genotoxic and cytotoxic effects of Zn deficiency or excess in a primary human oral keratinocyte cell line and determined the optimal concentration of two Zn compounds (Zn Sulphate (ZnSO4) and Zn Carnosine (ZnC)) to minimise DNA damage. Zn-deficient medium (0 μM) was produced using Chelex treatment, and the two Zn compounds ZnSO4 and ZnC were tested at concentrations of 0.0, 0.4, 4.0, 16.0, 32.0 and 100.0 μM. Cell viability was decreased in Zn-depleted cells (0 μM) as well as at 32 μM and 100 μM for both Zn compounds (P < 0.0001) as measured via the MTT assay. DNA strand breaks, as measured by the comet assay, were found to be increased in Zn-depleted cells compared with the other treatment groups (P < 0.05). The Cytokinesis Block Micronucleus Cytome assay showed a significant increase in the frequency of both apoptotic and necrotic cells under Zn-deficient conditions (P < 0.05). Furthermore, elevated frequencies of micronuclei (MNi), nucleoplasmic bridges (NPBs) and nuclear buds (NBuds) were observed at 0 and 0.4 μM Zn, whereas these biomarkers were minimised for both Zn compounds at 4 and 16 μM Zn (P < 0.05), suggesting these concentrations are optimal to maintain genome stability. Expression of PARP, p53 and OGG1 measured by western blotting was increased in Zn-depleted cells indicating that DNA repair mechanisms are activated. These results suggest that maintaining Zn concentrations within the range of 4–16 μM is essential for DNA damage prevention in cultured human oral keratinocytes.

Keywords

Zinc Cytotoxicity DNA damage Genomic stability Human oral keratinocytes Micronuclei 

Abbreviations

HOK

Human oral keratinocytes

CBMN-Cyt

Cytokinesis block micronucleus cytome assay

MTT

(3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)

MNi

Micronuclei

NPBs

Nucleoplasmic bridges

NBuds

Nuclear buds

Zn

Zinc

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Razinah Sharif
    • 1
    • 2
    • 3
  • Philip Thomas
    • 1
  • Peter Zalewski
    • 2
  • Michael Fenech
    • 1
  1. 1.CSIRO Food and Nutritional SciencesAdelaideAustralia
  2. 2.School of Medicine, Faculty of Health SciencesUniversity of AdelaideAdelaideAustralia
  3. 3.Program of Nutrition, School of Healthcare Sciences, Faculty of Health SciencesUniversiti Kebangsaan MalaysiaKuala LumpurMalaysia

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