Protein carbonylation is an irreversible modification to the side chain of amino acid residues induced by severe oxidative stress. Reactive oxygen species (ROS) are constantly produced under normal as well as stress-induced conditions, and play a role in both cancer progression and cancer suppression. Tumor tissue are known to have higher ROS levels compared to surrounding healthy tissue but ROS-induced specific protein carbonylation and its unique role in cancer progression/suppression are poorly understood. In this study we compared the relative total and specific protein carbonylation in flash frozen human breast cancer and matched adjacent normal tissue using ELISA, two-color western blot, mass spectrometry, and immunoprecipitation approaches. To understand antioxidant capacity in tumor tissue, we analyzed superoxide dismutase (SOD) for its antioxidant activity and protein level. Our results indicate that tumor tissue has greater total protein carbonylation, lower SOD activity, lower SOD protein levels, and elevated levels of autophagy compared to matched adjacent healthy tissue. We also identified three specific proteins that showed higher level of carbonylation selectively in tumor tissue compared to adjacent normal tissue. Our findings were further confirmed using the immortalized MDA-MB-231 breast cancer cell line and MCF-12A noncancerous normal human epithelial breast cell. Identification of selectively carbonylated proteins in cancer tissue, and understanding their specific role in cancer progression may promote the development of targeted therapeutic approaches to mitigate or enhance oxidative damage of such proteins selectively in tumor tissue.

Citation Format: Baikuntha P. Aryal, Ashutosh Rao. Oxidative stress and selective protein carbonylation in human breast cancer tissue [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5486. doi:10.1158/1538-7445.AM2017-5486