Plastic Surgery Research Council
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BIOCHEMISTRY OF DAMAGE AND REPAIR IN BREAST CANCER RECONSTRUCTION FOLLOWING RADIOTHERAPY
Presenter: Justin R Hubenak, BS
Co-Authors: OConnor C; Kronowitz SJ
MD Anderson

Background: The benefits of radiotherapy (RT) for cancer have been well documented for many years. However, even with targeted radiation delivery, many patients treated with radiation develop adverse effects and experience compromised wound healing. There is wide interpatient variation in adverse effects, and the underlying causes of this variation are not well defined.

Methods: Samples were collected from inpatients undergoing mastectomy surgery. Some patients received RT followed by tissue expander and flap reconstruction, while others received reconstructive surgery without RT. Patient samples were frozen in liquid nitrogen for protein extraction and immunofluorescence (IF) staining, while additional samples were fixed in formalin and paraffin embedded for immunohistochemistry (IHC) analysis. DNA damage protein expression was visualized histologically and quantified with ELISA and western blot by probing for proteins including PARP, H2AX, p53, Caspase-3 and others.

Results: DNA damage protein expression was found in patient samples with and without RT and at different stages of treatment. Within patient samples positive for H2AX expression, higher levels of non-phosphorylated PARP was also found. Patient samples following flap reconstruction show improved overall recovery with lower levels of DNA damage and apoptosis protein expression.

Conclusions: RT-induced increases in reactive oxide species in irradiated cells may signal healthy cells, causing them to enter alternate pathways affecting wound repair and leading to inflammation, fibrosis, and ultimately cell death by inhibiting DNA repair mechanisms. RT has a detectable effect on ?-H2AX and PARP levels that varies from patient to patient, possibly due to differences in patient DNA damage responses. Patients undergoing flap reconstruction showed generally lower levels of DNA damage repair protein expression even after RT, supporting the idea that secondary effects of RT can have far reaching effects on patient recovery.


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