Cigarette smoke-induced DNA damage and repair detected by the comet assay in HPV-transformed cervical cells

  • Authors:
    • Afsoon Moktar
    • Srivani Ravoori
    • Manicka V. Vadhanam
    • C. Gary Gairola
    • Ramesh C. Gupta
  • View Affiliations

  • Published online on: December 1, 2009     https://doi.org/10.3892/ijo_00000447
  • Pages: 1297-1304
Metrics: Total Views: 0 (Spandidos Publications: | PMC Statistics: )
Total PDF Downloads: 0 (Spandidos Publications: | PMC Statistics: )


Abstract

Human papillomavirus (HPV) is the causative factor in the development and progression of cervical cancers in >97% of the cases, although insufficient. Epidemiological studies suggest an elevated risk of cervical cancer for cigarette smokers; therefore, we examined cigarette smoke-induced DNA damage and repair in HPV16-transformed human ectocervical cells (ECT1/E6 E7). Cells were treated with cigarette smoke condensate (CSC) for 72 h to assess the formation of single- and double-strand DNA breaks, measured by alkaline and neutral single cell gel electrophoresis assays, respectively. The mean tail length of cells with single-strand breaks was increased by 1.8-, 2.7- and 3.7-fold (p<0.001) after treatment with 4, 8 and 12 µg/ml CSC, respectively. The tail length with double-strand breaks was also increased dose-dependently. These results were further supported by measurement of the mean tail moment: the increase in both single- and double-strand breaks were much more pronounced with increasing concentration of CSC, by up to 23.5-fold (p<0.0001 for both assays). To examine the DNA repair, cells were treated with CSC for 72 h, followed by CSC withdrawal and re-incubation of the cells with fresh medium for 24, 48, or 72 h. Both single- and double-strand DNA breaks were removed during the initial 24 h but no further removal of the damage was observed. Up to 80% of residual single- and double-strand DNA breaks (p<0.05) were found to persist at all CSC concentrations examined. Ellagic acid, a known antioxidant and free-radical scavenger, was found to significantly inhibit DNA breaks induced by CSC. Thus, free radicals may be a plausible source of CSC-induced DNA damage. These data show that CSC-mediated DNA strand breaks are highly persistent, and suggest that persistence of cigarette smoke-associated DNA damage in the presence of HPV infection may lead to increased mutations in cervical cells and ultimately higher cancer risk.

Related Articles

Journal Cover

December 2009
Volume 35 Issue 6

Print ISSN: 1019-6439
Online ISSN:1791-2423

Sign up for eToc alerts

Recommend to Library

Copy and paste a formatted citation
x
Spandidos Publications style
Moktar A, Ravoori S, Vadhanam MV, Gairola CG and Gupta RC: Cigarette smoke-induced DNA damage and repair detected by the comet assay in HPV-transformed cervical cells. Int J Oncol 35: 1297-1304, 2009.
APA
Moktar, A., Ravoori, S., Vadhanam, M.V., Gairola, C.G., & Gupta, R.C. (2009). Cigarette smoke-induced DNA damage and repair detected by the comet assay in HPV-transformed cervical cells. International Journal of Oncology, 35, 1297-1304. https://doi.org/10.3892/ijo_00000447
MLA
Moktar, A., Ravoori, S., Vadhanam, M. V., Gairola, C. G., Gupta, R. C."Cigarette smoke-induced DNA damage and repair detected by the comet assay in HPV-transformed cervical cells". International Journal of Oncology 35.6 (2009): 1297-1304.
Chicago
Moktar, A., Ravoori, S., Vadhanam, M. V., Gairola, C. G., Gupta, R. C."Cigarette smoke-induced DNA damage and repair detected by the comet assay in HPV-transformed cervical cells". International Journal of Oncology 35, no. 6 (2009): 1297-1304. https://doi.org/10.3892/ijo_00000447