Interplay between membrane lipid peroxidation, transglutaminase activity, and cyclooxygenase 2 expression in the tissue adjoining to breast cancer.

Breast cancer, a leading cause of cancer related deaths worldwide, is one of the most common neoplasms in women. The increased generation of reactive oxygen species (ROS) in breast lesion is critically involved in the mutagenic processes that drive to breast carcinoma initiation and progression. To date, the molecular events occurring in the tissue adjoin the cancer lesion have not been elucidated. Here, we investigated the role of excess ROS generation during human breast carcinogenesis by evaluating oxidative stress biomarkers, tissue transglutaminase (t-TGase) activity, and expression levels of ubiquitin and cyclooxygenase-2 (COX-2) in the normal tissue adjoin to fibroadenoma (nFA), atypical ductal hyperplasia (nADH), and invasive ductal carcinoma (nIDC) from 45 breast cancer patients. We found that lipid peroxidation and nitric oxide production significantly increased in nIDC respect to nFA and nADH (P < 0.005) whereas the 4-hydroxy-2-nonenal (HNE) protein-adducts increased only in nADH (P < 0.005). The increased lipid damage observed in nIDC correlates with estrogen receptor exposure in IDC (R(2) = 0.89). Moreover, nIDC and invasive ductal carcinoma (IDC) showed a 10-fold higher t-TGase activity compared to nFA and nADH. Contrary, COX-2 expression levels significantly decreased nIDC and IDC respect to the nFA and nADH (P < 0.001). The analysis of the free ubiquitin expression revealed equal levels in nADH and nIDC samples whereas high molecular weight-ubiquitin conjugate increased about fivefold only in nIDC (P < 0.01 vs. nADH). These novel findings reveal an interplay between membrane lipid peroxidation, t-TGase activity, and COX-2 expression levels in the tissue adjoining to neoplastic lesion during breast cancer progression.