A COMPARISON OF DNA DAMAGE PROBES IN TWO HMEC LINES WITH X-IRRADIATION

In this study, we investigated γH2AXser139 and 53BP1ser25, DNA damage pathway markers, to observe responses to radiation insult. Two Human Mammary Epithelial Cell (HMEC) lines were utilized to research the role of immortalization in DNA damage marker expression, HMEC HMT-3522 (S1) with an infi nite lifespan, and a subtype of HMEC 184 (184V) with a fi nite lifespan. Cells were irradiated with 50cGy X-rays, fi xed with 4% paraformaldehyde after 1 hour repair at 37°C, and processed through immunofl uorescence. Cells were visualized with a fl uorescent microscope and images were digitally captured using Image-Pro Plus software. The 184V irradiated cells exhibited a more positive punctate response within the nucleus for both DNA damage markers compared to the S1 irradiated cells. The dose and time course will be expanded in future studies to augment the preliminary data from this research. It is important to understand whether the process of transformation to immortalization compromises the DNA damage sensor and repair process proteins of HMECs in order to understand what is “normal” and to evaluate the usefulness of cell lines as experimental models