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Analysis of DNA Double-strand Break (DSB) Repair in Mammalian Cells
13:10

Analysis of DNA Double-strand Break (DSB) Repair in Mammalian Cells

Published on: September 9, 2010

Deficient double-strand break repair in oral squamous cell carcinoma cell lines

Maryam Jessri1, Andrew J Dalley1, Camile S Farah1,2

  • 1Oral Oncology Research Program, UQ Centre for Clinical Research, The University of Queensland, Herston, Qld, Australia.

Journal of Oral Pathology & Medicine : Official Publication of the International Association of Oral Pathologists and the American Academy of Oral Pathology
|April 7, 2017
PubMed
Abstract

Insights

Oral cancer cells show impaired DNA double-strand break (DSB) repair, suggesting genetic defects contribute to oral squamous cell carcinoma (OSCC) development. This defective repair system in neoplastic cells hinders their ability to maintain genomic integrity.

Area of Science:

  • Oncology
  • Genetics
  • Molecular Biology

Background:

  • Approximately 20% of oral squamous cell carcinoma (OSCC) cases lack clear environmental causes, indicating a role for genetic factors.
  • DNA double-strand breaks (DSBs) threaten genomic integrity, and their inefficient repair can accelerate somatic mutations during tumorigenesis.
  • DSBs are critical in the development of OSCC.

Purpose of the Study:

  • To investigate the kinetics and efficiency of DNA double-strand break (DSB) repair in oral cell lines across different stages of oral tumorigenesis.
  • To compare the DSB repair capacity between normal, dysplastic, and oral squamous cell carcinoma (OSCC) cell lines.

Main Methods:

  • Induced DSBs in oral cell lines (normal, dysplastic, OSCC) using hydrogen peroxide and camptothecin.
  • Quantified DSB repair kinetics indirectly by counting gamma histone 2Ax (γH2Ax) foci.
  • Confirmed DSB levels and repair dynamics using Western blot analysis of γH2Ax, Nbs1, and ATM expression.

Main Results:

  • Neoplastic (OSCC) cell lines exhibited the slowest DNA double-strand break (DSB) repair rates and lowest maximal DSB numbers compared to normal and dysplastic cells.
  • Gamma histone 2Ax (γH2Ax) foci kinetics, as observed via immunofluorescence, were corroborated by Western blot analysis.
  • ATM and Nbs1 expression levels showed minimal changes, though ATM levels slightly increased in normal cells post-treatment.

Conclusions:

  • Oral cell lines display varying efficiencies in DNA double-strand break (DSB) repair pathways.
  • Neoplastic cell lines possess the most compromised DSB repair systems, contributing to genomic instability in oral squamous cell carcinoma (OSCC).
Keywords:
double strand break repairdysplasiaoral squamous cell carcinomaγH2Ax

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