Growth suppression of human breast carcinoma stem cells by lipid peroxidation product 4-hydroxy-2-nonenal and hydroxyl radical-modified collagen.

Breast cancer is a leading cause of mortality and morbidity in women, mostly due to high metastatic capacity of mammary carcinoma cells. It has been revealed recently that metastases of breast cancer comprise a fraction of specific stem-like cells, denoted as cancer stem cells (CSCs). Breast CSCs, expressing specific surface markers CD44(+)CD24(-/low)ESA(+) usually disseminate in the bone marrow, being able to spread further and cause late metastases. The fundamental factor influencing the growth of CSCs is the microenvironment, especially the interaction of CSCs with extracellular matrix (ECM). The structure and function of ECM proteins, such as the dominating ECM protein collagen, is influenced not only by cancer cells but also by various cancer treatments. Since surgery, radio and chemotherapy are associated with oxidative stress we analyzed the growth of breast cancer CD44(+)CD24(-/low)ESA(+) cell line SUM159 cultured on collagen matrix in vitro, using either native collagen or the one modified by hydroxyl radical. While native collagen supported the growth of CSCs, oxidatively modified one was not supportive. The SUM159 cell cultures were further exposed to a supraphysiological (35 microM) dose of the major bioactive lipid peroxidation product 4-hydroxynonenal (HNE), a well known as 'second messenger of free radicals', which has a strong affinity to bind to proteins and acts as a cytotoxic or as growth regulating signaling molecule. Native collagen, but not oxidised, abolished cytotoxicity of HNE, while oxidized collagen did not reduce cytotoxicity of HNE at all. These preliminary findings indicate that beside direct cytotoxic effects of anticancer therapies consequential oxidative stress and lipid peroxidation modify the microenvironment of CSCs influencing oxidative homeostasis that could additionally act against cancer.

Interactions of oxidatively modified calf skin collagen with platelets and phagocytes.

OBJECTIVES: The effects of non-modified and oxidatively modified calf skin collagen type I on platelet aggregation and the oxidative burst of phagocytes were examined in the framework of a general hypothesis that collagen, platelets and phagocytes cooperate to modulate the oxidative burst of phagocytes and the extent of oxidative stress. MATERIALS AND METHODS: Calf skin collagen type I was subjected to oxidative modification by hydrogen peroxide or hydroxyl radical. Thermal denaturation of collagen was performed in a spectrophotometer equipped with a temperature gradient device. The aggregation of isolated human platelets obtained after differential centrifugation was measured using a dual-channel aggregometer. The production of reactive oxygen species by human whole blood phagocytes was evaluated by luminol-enhanced chemiluminescence. RESULTS: Oxidative modification of collagen samples was characterized by a decrease in denaturation transition temperature. Oxidatively modified samples showed a modified SDS-PAGE pattern, evidencing a significant destruction of the collagen. All oxidatively modified collagen samples, independent of the oxidation treatment applied, lost their platelet-aggregating and phagocyte oxidative burst-inducing activity. CONCLUSION: The results suggest that reactive oxygen species were able to modify collagen. On the other hand, oxidatively modified collagen lost its activating properties towards platelets and phagocytes.