Terahertz (THz) photons don't have sufficient energy to break apart the bonds that bind DNA in a cell's nucleus. But theoretical research suggests that picosecond THz pulses may amplify the natural vibrations of hydrogen bonds that bind DNA strands, and thus create openings between the strands. Now, new research has looked to discover whether this destabilization is sufficient to cause breaks.1
In their study, Canadian researchers at the University of Alberta (Edmonton, AB) and the University of Lethbridge (Lethbridge, AB) exposed laboratory-grown human skin tissue to intense THz pulses and found signs of DNA damage through a chemical marker called phosphorylated H2AX.
|Confocal fluorescence images of tissue sample cross-sections show the incidence of γH2AX foci (localized green spots). Blue spots indicate cell nuclei. γH2AX-harboring cells (markers for double strand breaks in DNA) inside cell nuclei appear as blue-green spots. Panels from left to right show representative images for control (CT), low THz pulse energy (0.1 μJ), high THz pulse energy (1.0 μJ), and UVA-exposed tissues. (Image courtesy of Biomedical Optics Express)|
Once DNA breaks occur, they can eventually lead to tumors if unrepaired. So it is interesting that simultaneously, the researchers noticed that the pulses triggered an increase in the levels of multiple tumor suppressor and cell-cycle regulatory proteins that facilitate DNA repair. This, they say, may suggest that DNA damage in human skin arising from such intense THz exposure could be quickly repaired, and the risk of carcinogenesis minimized.
The researchers hope to explore the potential therapeutic effects of intense THz radiation exposure to see if directed treatment with such pulses can become a new tool to fight cancer.
1. L. V. Titova et al., Biomed. Opt. Exp., 4, 559–568 (2013).