Helén Andersson

Low levels of the air pollutant 1-nitropyrene induce DNA damage, increased levels of reactive oxygen species and endoplasmic reticulum stress in human endothelial cells

Both epidemiological and experimental studies suggest that exposure to high levels of air pollution is a risk factor associated with cardiovascular disease. Traffic emission is a major source of exposure to persistent air pollutants such as nitrated polycyclic aromatic hydrocarbons (nitro-PAHs). 1-Nitropyrene (1-NP), one of the most abundant nitro-PAHs in diesel exhausts, was selected as a model nitro-PAH for the present study. The aim of the study was to investigate the effects of 1-NP in human umbilical vein endothelial cells (HUVECs) and the metabolic pathways involved. The nitroreductase inhibitor dicoumarol and the coplanar aryl hydrocarbon receptor (AhR) ligand PCB 126 were used to modulate the metabolism of 1-NP. The results revealed that low levels (< or =10microM) of 1-NP induced DNA damage, increased levels of reactive oxygen species (ROS) and increased protein expression of the endoplasmic reticulum (ER) stress chaperone GRP78. A decrease in cell viability was only observed following exposure to a higher level of 1-NP (15microM). Inhibition of nitroreductive metabolism by dicoumarol attenuated the induction of DNA damage, intracellular ROS levels and GRP78 expression. This suggests that the effects of 1-NP on HUVEC were mediated by metabolites mainly formed at nitroreduction. Our findings suggest that the human blood vessel endothelium is a sensitive target tissue for the major nitro-PAH constituent in diesel exhaust.

Tamoxifen-induced adduct formation and cell stress in human endometrial glands.

The beneficial effects of tamoxifen in the prevention and treatment of breast cancer are compromised by an increased risk of endometrial polyps, hyperplasia, and cancer. Tamoxifen is metabolized to an array of metabolites with estrogenic effects but also to reactive intermediates that may form protein and DNA adducts. The aim of this study was to investigate cellular [3H]tamoxifen adduct formation by light microscopic autoradiography and cell stress by immunohistochemical analysis of glucose-regulating protein 78 (GRP78), nuclear factor κB (NF-κB), and caspase 3 in human endometrial explants after short-term incubation with tamoxifen. The cellular expression of tamoxifen-metabolizing enzymes in human endometrial biopsy samples was also determined by immunohistochemistry. The results showed selective [3H]tamoxifen adduct formation in glandular and surface epithelia after incubation with a nontoxic concentration of [3H]tamoxifen (6 nM). There was also a selective expression of the endoplasmic reticulum stress chaperone GRP78 and activated caspase 3 at these sites after incubation with cytotoxic concentrations of tamoxifen (10–100 μM). The cell stress was preferentially observed in samples from women in the proliferative menstrual phase. No treatment-related expression of NF-κB was observed. Constitutive expression of the tamoxifen-metabolizing enzymes CYP1B1, CYP2A6, CYP2B6, CYP2C8/9/19, CYP2D6, and SULT2A1 in glandular and surface epithelia was shown, but there was a large interindividual variation. The colocalization of [3H]tamoxifen adducts, expression of GRP78, caspase 3, and tamoxifen-metabolizing enzymes in human glandular and surface epithelia suggest a local bioactivation of tamoxifen at these sites and that epithelial cells are early target sites for tamoxifen-induced cell stress.

Tamoxifen modulates cell migration and expression of angiogenesis-related genes in human endometrial endothelial cells.

The selective estrogen receptor modulator tamoxifen is used for the prevention and treatment of breast cancer. The adverse effects of tamoxifen include vaginal endometrial bleeding, endometrial hyperplasia, and cancer, conditions associated with angiogenesis. The aim of this study was to examine the effects of tamoxifen on cell migration and angiogenesis-related gene expression in human endometrial endothelial cells (HEECs). The regulatory effects of tamoxifen on endometrial stromal cells and HEECs were also examined. HEECs and stromal cells were isolated and grown in monocultures or co-cultures, and incubated with 0.1 to 100 μmol/L tamoxifen for 48 hours. Quantitative PCR demonstrated that tamoxifen decreased the mRNA expression of vascular endothelial growth factor-A (VEGF-A) and increased the mRNA expression of VEGF receptor-1 and placental growth factor (PLGF) in HEECs. Tamoxifens effects on VEGF-A were inhibited when HEECs were co-cultured with stromal cells. In addition, tamoxifen reduced VEGF-induced HEEC migration. The tamoxifen-metabolizing enzymes CYP1A1 and CYP1B1 were detected by immunohistochemistry in and around endometrial blood vessels and by quantitative PCR in HEECs. Our data suggest that tamoxifen changes the regulation of angiogenesis in the endometrium, likely by reducing angiogenic activity. The results also indicate that endometrial stromal cells regulate some of tamoxifens effects in HEECs, and the presence of tamoxifen-metabolizing enzymes suggests tamoxifen bioactivation in the endometrial vasculature in vivo. These findings may help to elucidate the mechanism of the bleeding disturbances associated with tamoxifen treatment.

‘My little wild fever-struck brother’: human and animal subjectivity in Hélène Cixous’ Algeria

ABSTRACT This article examines the place of human and animal subjectivity in two autobiographically informed texts by Hélène Cixous. It takes her view on the word ‘human’ and the figure of Fips, the dog of the Cixous family, as a point of departure. By thinking through this figure, I argue, Cixous analyses the dehumanizing logic of colonialism and anti-Semitism in Algeria and develops her own response to such kinds of political evils, arguing for human relationality and animal corporeality. The article shows that Cixous’ meeting with Fips creates a stigma that, belatedly, breaks through the barrier between herself and the dog; the reopening of the wound takes place in a poetical writing that reveals an intense ‘animal humanity’ formed by communal suffering, finiteness, and love. The lesson Cixous learns from the memory of Fips the dog is how to become ‘better human’. This becoming is also an assault on the false humanism of the colonial project and on racialized social exclusion.