Open AccessBiological Effects of Passive Versus Active Scanning Proton Beams on Human Lung Epithelial Cells
Author(s) -
Daila S. Gridley,
Michael J. Pecaut,
Xiao Wen Mao,
Andrew Wroe,
Xian Luo-Owen
Publication year - 2015
Publication title -
technology in cancer research and treatment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.754
H-Index - 63
eISSN - 1533-0346
pISSN - 1533-0338
DOI - 10.7785/tcrt.2012.500392
Subject(s) - bragg peak , proton therapy , nuclear medicine , microbiology and biotechnology , chemistry , proton , biology , medicine , physics , quantum mechanics
The goal was to characterize differences in cell response after exposure to active beam scanning (ABS) protons compared to a passive delivery system. Human lung epithelial (HLE) cells were evaluated at various locations along the proton depth dose profile. The dose delivered at the Bragg peak position was essentially identical (∼4 Gy) with the two techniques, but depth dose data showed that ABS resulted in lower doses at entry and more rapid drop-off after the peak. Average dose rates for the passive and ABS beams were 1.1 Gy/min and 5.1 Gy/min, respectively; instantaneous dose rates were 19.2 Gy/min and 2,300 Gy/min (to a 0.5 × 0.5 mm 2 voxel). Analysis of DNA synthesis was based on 3 H-TdR incorporation. Quantitative real-time polymerase chain reaction (RT-PCR) was done to determine expression of genes related to p53 signaling and DNA damage; a total of 152 genes were assessed. Spectral karyotyping and analyses of the Golgi apparatus and cytokines produced by the HLE cells were also performed. At or near the Bragg peak position, ABS protons resulted in a greater decrease in DNA synthesis compared to passively delivered protons. Genes with >2-fold change (P 2-fold difference with ABS protons: BRCA1, BRCA2, CDC25A, CDC25C, CCNB2, CDK1, DMC1, DNMT1, E2F1, EXO1, FEN1, GADD45A, GTSE1, IL-6, JUN, KRAS, MDM4, PRC1, PTTG1, RAD51, RPA1, TNF, WT1, XRCC2, XRCC3 and XRCC6BP1. Spectral karyotyping revealed numerous differences in chromosomal abnormalities between the two delivery systems, especially at or near the Bragg peak. Percentage of cells staining for the Golgi apparatus was low after exposure to passive and active proton beams. Studies such as this are needed to ensure patient safety and make modifications in ABS delivery, if necessary.