[Exploration of relationship between the expression level of DNA polymerase beta and 60Co gamma-ray radiosensitivity]

Sichuan Da Xue Xue Bao Yi Xue Ban. 2011 Nov;42(6):745-50.
[Article in Chinese]


Objective: To explore the relationship between the expression level of DNA polymerase beta (pol beta) and 60Co gamma-ray radiosensitivity and provide a basis on improving the efficiency of radiotherapy theoretically.

Methods: pol beta wild-type cells (pol beta +/+), pol beta null cells (pol beta -/-) and pol beta overexpressed cells (polp beta oe) were applied as a model system. The radiosensitivity of 60Co gamma-ray on the cell was detected by MTT assay and clone formation assay. The DCFH-DA fluorescent probe was used to examine the cellular ROS after 60Co gamma-rays radiation.

Results: MTT assay showed that after radiation by 60Co gamma-rays followed with 72 h incubation, the cell viabilities in the three kinds of cells decreased significantly with a dose-response relationship (r-/+ = -0.976, r-/- = -0.977, r(oe) = -0.982, P<0.05). In addition, the viability of pol beta -/- cell was lower than those of other two kinds of cells at the same dose (P<0.05). Likewise, the colony number and colony formation rate in all tested cells also decreased after exposure to 60Co gamma-rays. The ROS level in the three kinds of cells was enhanced after treatment with 60Co gamma-ray, and the ROS level in pol beta -/- cells was much higher than that in the other two kinds of cells (P<0.05).

Conclusion: Cell death caused by 60Co gamma-ray may associated with the DNA oxidative damage mediated by ROS; Overexpression of pol beta could protect against oxidative DNA damage, thus the cell apoptosis/death, thereby leading to reducing the radiosensitivity of 60Co gamma-rays, while null of DNA pol beta could increase radiosensitivity of 60Co gamma-rays by compromising the DNA repair.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Cobalt Radioisotopes / pharmacology*
  • DNA Damage / radiation effects*
  • DNA Polymerase beta / genetics
  • DNA Polymerase beta / metabolism*
  • Dose-Response Relationship, Radiation
  • Embryo, Mammalian
  • Fibroblasts / cytology
  • Fibroblasts / enzymology
  • Fibroblasts / radiation effects*
  • Gamma Rays
  • Mice
  • Radiation Tolerance / genetics*
  • Reactive Oxygen Species / metabolism


  • Cobalt Radioisotopes
  • Reactive Oxygen Species
  • DNA Polymerase beta