Growth on HNE modified collagen induce Nrf2 in breast cancer stem cells

Oxidative stress is an important factor in carcinogenesis. In addition, radiotherapy, chemotherapy and inflammation increase oxidative stress in tumors. Lipid peroxidation end product, a reactive aldehyde 4-hydroxy-2-nonenal (HNE), is considered to be second messenger of oxidative stress. HNE modifies the metabolism of cancer cells by interacting with proteins, lipids and DNA. Along with oxidative stress, cancer stem cells have been recognized as the crucial factor in cancer malignancy and are considered responsible for metastasis occurrence, therapy resistance and, finally, recurrence of the disease. For these reasons we examined the effect of HNE induced oxidative stress and HNE modulation of the extracellular matrix on cancer stem cells metabolism, proliferation and their antioxidative mechanisms. Collagen was used as a representative protein of extracellular matrix and was modified with HNE. Cells were plated on native and HNE-modified collagen as well as polystyrene surface and were additionally treated with HNE every second day. Afterwards, we determined viability and proliferation with MTT and 3HT test. Antioxidant cell capacity was assessed by glutathione and catalase assay. Dot-blot analysis was performed in order to quantify Nrf2 and HNE histidine conjugates. We confirmed specificity of dot-blot findings by performing western blot analysis of Nrf2. The results suggest that the aggressive cancer stem cell phenotype is enhanced during chronic oxidative stress. Extracellular matrix alterations resulting from oxidative stress may cause an adaptation of cancer stem cells, enabling them to survive increased oxidative stress.