Differences in DNA Repair Capacity, Cell Death and Transcriptional Response after Irradiation between a Radiosensitive and a Radioresistant Cell Line.

Maria Gomolka,Joan-Francesc Barquinero,Mireia Borràs-Fresneda,Ute Rössler,Leonardo Barrios,Gemma Armengol,Sabine Hornhardt

doi:10.1038/srep27043

Abstract

Normal tissue toxicity after radiotherapy shows variability between patients, indicating inter-individual differences in radiosensitivity. Genetic variation probably contributes to these differences. The aim of the present study was to determine if two cell lines, one radiosensitive (RS) and another radioresistant (RR), showed differences in DNA repair capacity, cell viability, cell cycle progression and, in turn, if this response could be characterised by a differential gene expression profile at different post-irradiation times. After irradiation, the RS cell line showed a slower rate of γ-H2AX foci disappearance, a higher frequency of incomplete chromosomal aberrations, a reduced cell viability and a longer disturbance of the cell cycle when compared to the RR cell line. Moreover, a greater and prolonged transcriptional response after irradiation was induced in the RS cell line. Functional analysis showed that 24 h after irradiation genes involved in “DNA damage response”, “direct p53 effectors” and apoptosis were still differentially up-regulated in the RS cell line but not in the RR cell line. The two cell lines showed different response to IR and can be distinguished with cell-based assays and differential gene expression analysis. The results emphasise the importance to identify biomarkers of radiosensitivity for tailoring individualized radiotherapy protocols.

Highlights

Several promising biomarkers of cellular radiosensitivity have been tested, there is not enough evidence of their utility in clinical practice[9]
The aim of the present study was to determine if these differences could be related to DNA repair capacity, cell cycle progression or cell death and, in turn, if this response could be characterised by a differential gene expression profile at different post-irradiation times
After irradiation, a slower rate of γ-H2AX foci disappearance, a higher frequency of incomplete chromosome elements, a reduced cell viability and a higher cell cycle disturbance were observed in the RS cell line in comparison with the RR cell line

Summary

Introduction

Several promising biomarkers of cellular radiosensitivity have been tested, there is not enough evidence of their utility in clinical practice[9]. DNA damage markers, those related with DNA double-strand breaks (DSBs), have been analysed and a certain level of association between cellular radiosensitivity tested in vitro and normal tissue reactions after radiotherapy has been observed[10,11,12,13,14,15]. On this basis, increased chromosomal aberration yields in peripheral blood lymphocytes and cell lines have been linked to radiosensitivity following in vitro ionising radiation (IR)[16,17]. The aim of the present study was to determine if these differences could be related to DNA repair capacity, cell cycle progression or cell death and, in turn, if this response could be characterised by a differential gene expression profile at different post-irradiation times

Objectives

Methods

Results

Conclusion