Proton Beams Inhibit Proliferation of Breast Cancer Cells by Altering DNA Methylation Status

Area of Science:

• Oncology
• Epigenetics
• Radiation Biology

Background:

• Proton beam therapy is increasingly used for various cancers.
• The impact of proton beams on cancer cell epigenetics, specifically DNA methylation, remains largely unexplored.

Purpose of the Study:

• To investigate the effects of proton beam radiation on DNA methylation patterns in breast cancer cell lines.
• To explore the correlation between proton beam-induced epigenetic alterations and changes in gene expression and cell proliferation.

Main Methods:

• Utilized pyrosequencing to analyze DNA methylation of the LINE1 gene in MCF-10A and MCF-7 cells.
• Performed genome-wide methylation analysis on MCF-7 cells.
• Assessed cell proliferation using colony formation and cell proliferation assays.
• Quantified the expression levels of selected genes post-proton beam treatment.

Main Results:

• Proton beam treatment led to significant hypermethylation at specific CpG sites in both MCF-10A and MCF-7 cell lines.
• Genome-wide analysis in MCF-7 cells revealed networks associated with developmental, hereditary, and metabolic disorders.
• A notable decrease in cell proliferation was observed in proton beam-treated cells.
• Expression of genes like MDH2, STYXL1, CPE, FAM91A1, and GPR37 changed significantly, correlating with methylation level shifts.

Conclusions:

• Proton beam therapy induces significant epigenetic modifications, primarily DNA methylation changes, in breast cancer cells.
• These methylation alterations are linked to decreased cell proliferation and altered gene expression.
• The findings provide an epigenetic foundation for understanding proton beam therapy's mechanism of action in cancer management.