DNA methylation changes in cells regrowing after fractioned ionizing radiation.

Area of Science:

• Molecular Biology
• Cancer Research
• Epigenetics

Background:

• Repeated exposure to ionizing radiation (IR) can induce adaptive responses.
• While DNA methylation changes are known for drug stress, their role in fractionated IR is unclear.

Purpose of the Study:

• Investigate DNA methylation alterations in MCF7 breast cancer cells following fractionated ionizing radiation (FIR).
• Identify specific genes affected by FIR-induced DNA methylation changes.

Main Methods:

• MCF7 cells were exposed to fractionated IR (2 Gy/fraction, 5 times/week) at total doses of 10 and 20 Gy.
• Methyl-CpG immunoprecipitation (MCIp) followed by CpG island microarray analysis was used to profile methylation.
• Time-of-flight mass spectrometry confirmed methylation changes in specific genes.

Main Results:

• FIR induced DNA methylation changes in CpG islands 48 hours after treatment.
• Cells treated with 10 Gy FIR regrew after 14 days, showing radioresistance.
• Differential methylation was confirmed for CpG units associated with FOXC1 and TRAPPC9.

Conclusions:

• Regrowth of MCF7 cells after 10 Gy FIR is linked to locus-specific DNA methylation alterations.
• These findings highlight the role of epigenetics in cellular adaptation to fractionated ionizing radiation.