Radiat Oncol J.  2022 Mar;40(1):66-78. 10.3857/roj.2021.00689.

PA1 cells containing a truncated DNA polymerase β protein are more sensitive to gamma radiation

• Patra A
• Nag A
• Chakraborty A
• Bhattacharyya N

• KMID: 2527630
• DOI: http://doi.org/10.3857/roj.2021.00689

Abstract

Purpose
DNA polymerase β (Polβ) acts in the base excision repair (BER) pathway. Mutations in DNA polymerase β (Polβ) are associated with different cancers. A variant of Polβ with a 97 amino acid deletion (PolβΔ), in heterozygous conditions with wild-type Polβ, was identified in sporadic ovarian tumor samples. This study aims to evaluate the gamma radiation sensitivity of PolβΔ for possible target therapy in ovarian cancer treatment.
Materials and Methods
PolβΔ cDNA was cloned in a GFP vector and transfected in PA1 cells. Stable cells (PA1PolβΔ) were treated with 60Co sourced gamma-ray (0–15 Gy) to investigate their radiation sensitivity. The affinity of PolβΔ with DNA evaluated by DNA protein in silico docking experiments. Result: The result showed a statistically significant (p < 0.05) higher sensitivity towards radiation at different doses (0–15 Gy) and time-point (48–72 hours) for PA1PolβΔ cells in comparison with normal PA1 cells. Ten Gy of gamma radiation was found to be the optimal dose. Significantly more PA1PolβΔ cells were killed at this dose than PA1 cells after 48 hours of treatment via an apoptotic pathway. The in silico docking experiments revealed that PolβΔ has more substantial binding potential towards the dsDNA than wild-type Polβ, suggesting a possible failure of BER pathway that results in cell death.
Conclusion
Our study showed that the PA1PolβΔ cells were more susceptible than PA1 cells to gamma radiation. In the future, the potentiality of ionizing radiation to treat this type of cancer will be checked in animal models.

Keyword

DNA polymerase β; Base excision repair; Ovarian cancer; Radiation therapy; Docking