Cigarette smoke condensate-induced oxidative DNA damage and its removal in human cervical cancer cells

Int J Oncol. 2011 Oct;39(4):941-7. doi: 10.3892/ijo.2011.1106. Epub 2011 Jun 29.

Abstract

Exposure to cigarette smoke is well documented to increase oxidative stress and could account for higher risk of cervical cancer in smokers. Cervical pre-cancerous lesions that are initiated by human papillomavirus (HPV) infection generally regress in the absence of known risk factors such as smoking. 8-oxodeoxyguanosine (8-oxodG) is a highly mutagenic oxidative DNA lesion that is formed by the oxidation of deoxyguanosine. In the present study, we examined: a) the effect of cigarette smoke condensate (CSC) on 8-oxodG formation in and its removal from HPV-transfected (ECT1/E6 E7), HPV-positive (CaSki) and HPV-negative (C33A) human cervical cancer cells, and b) the cell cycle progression and apoptosis in CSC-treated ECT1/E6 E7 cells. CSC induced 8-oxodG in a dose- (p=0.03) and time (p=0.002)-dependent fashion in ECT1/E6 E7 cells as determined by flow cytometry. A 2.4-fold higher level of 8-oxodG was observed in HPV-positive compared with HPV-negative cells. However, 8-oxodG lesions were almost completely removed 72 h post-exposure in all cell lines as determined by ImageStream analysis. This observation correlates with the 2- and 5-fold increase in the p53 levels in ECT1/E6 E7 and CaSki cells with no significant change in C33A cells. We conclude that: a) cigarette smoke constituents induce oxidative stress with higher burden in HPV-positive cervical cancer cells and b) the significant increase observed in p53 levels in wild-type cervical cells (ECT1/E6 E7 and CaSki) may be attributed to the p53-dependent DNA repair pathway while a p53-independent pathway in C33A cells cannot be ruled out.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 8-Hydroxy-2'-Deoxyguanosine
  • Apoptosis / genetics
  • Cell Cycle / genetics
  • Cell Line, Transformed
  • Cell Line, Tumor
  • Cell Transformation, Viral
  • DNA Damage*
  • DNA Repair / genetics
  • Deoxyguanosine / analogs & derivatives
  • Deoxyguanosine / biosynthesis
  • Female
  • Genes, p53 / genetics
  • Human papillomavirus 16 / physiology
  • Humans
  • Nicotiana*
  • Oxidative Stress / genetics*
  • Papillomavirus Infections / complications
  • Papillomavirus Infections / metabolism
  • Risk Factors
  • Smoke / adverse effects*
  • Uterine Cervical Neoplasms / etiology*
  • Uterine Cervical Neoplasms / genetics
  • Uterine Cervical Neoplasms / pathology
  • Uterine Cervical Neoplasms / virology

Substances

  • Smoke
  • 8-Hydroxy-2'-Deoxyguanosine
  • Deoxyguanosine