INVOLVEMENT OF THE REDOX POTENTIAL IN DEVELOPMENT OF RESISTANCE TO TREATMENT IN BREAST CANCER

This paper aims to identify a potential mechanism of tumour resistance to chemotherapy treatment due to the drug transport. In this study only breast cancer patients were included. Depending on the response to chemotherapy and progression of disease, the patients were divided into two groups: patients with resistance to chemotherapy (group 1) and patients with response to chemotherapy (group 2). Proteins involved in redox reactions (e.g., ceruloplasmin), the thiol (-SH) groups from albumin, and nitrogen oxide (NO) resulted from protein oxidative attack were determined by biochemical assays. The results show that copper-oxidase activity of ceruloplasmin increases in cancer patients compared to normal values reported in literature (i.e., 80-120 IU). Increased levels of free thiols in patients included in the group 1 are on average higher with 12.4 % as compared to group 2. The serum NO concentration has shown values above the normal range (7-14) mu mol/l. We conclude that hypoxic stress proteins and redox potential modifications may induce resistance to chemotherapeutic agents.