4-Aminobiphenyl-hemoglobin adducts and risk of smoking-related disease in never smokers and former smokers in the European Prospective Investigation into Cancer and Nutrition prospective study.

The aim of this study was to evaluate whether biomarkers of environmental tobacco smoke exposure [i.e., 4-aminobiphenyl-hemoglobin (4-ABP-Hb) adducts] were predictive of the risk of tobacco-related cancers and diseases. We did a case-control study nested within the European Prospective Investigation into Cancer and Nutrition, involving 190 controls and 149 cases (incident cancer of the lung, bladder, pharynx, larynx, oral cavity, leukemias, and chronic obstructive pulmonary disease or emphysema deaths). All individuals were never smokers or ex smokers for >10 years. 4-ABP-Hb adducts were analyzed in peripheral blood collected before the onset of the disease (median, 7 years). Overall, 4-ABP-Hb adducts were higher, although not statistically significantly so, in cases (as a whole) than controls. In the control population, high fruit and vegetable consumption significantly lowered the frequency of detectable adducts (Fisher's exact test, P = 0.025). Restricting the analysis to women, 4-ABP-Hb adducts were higher in cases than controls (Mann-Whitney P = 0.036) and the odds ratio (OR) for the presence/absence of adducts was 2.42 [95% confidence interval (95% CI), 1.18-4.98]. Moreover, the association of adducts with the individual cancer types was stronger in women than in the whole study population, although statistically significant only for leukemias (OR, 2.77; 95% CI, 1.06-7.20). The results provide some evidence that women may be more susceptible to environmental tobacco smoke, as suggested by their higher adduct levels. The most important finding of this prospective study is that, at least in women, 4-ABP-Hb adducts may help identify subjects at high risk of cancers related to environmental tobacco smoke exposure.

Eicosapentaenoic acid inhibits endothelial cell migration in vitro.

BACKGROUND: As n-3 Polyunsaturated Fatty Acids exert a beneficial action on the cardiovascular system, it is important to investigate their effects on endothelial cell responses that (like migration) contribute to repairing vascular lesions. METHODS: To this purpose, using functional and morphological in vitro assays, we have examined the effect of n-3 Polyunsaturated Fatty Acids on the migration of endothelial cells. RESULTS: We report here that incubation of endothelial cells with n-3 Polyunsaturated Fatty Acids impaired cell migration into a wound, triggered peripheral distribution of focal adhesions and caused partial disassembly of actin filaments. We also found that eicosapentaenoic acid and docosahexaenoic acid exerted similar effects on the focal adhesions, but that eicosapentaenoic acid was sufficient for inhibiting cell migration. CONCLUSIONS: Given the importance of endothelial cell migration in the repair of vascular injuries, these in vitro findings call for in vivo evaluation of vascular repair in response to different dietary ratios of eicosapentaenoic to docosahexaenoic acid.

Opposite effects of tumor necrosis factor and soluble fibronectin on junctional adhesion molecule-A in endothelial cells.

Junctional adhesion molecule-A (JAM-A) regulates key inflammatory responses, such as edema formation and leukocyte transmigration. Although it has been reported that the inflammatory cytokine tumor necrosis factor (TNF) causes the disassembly of JAM-A from the intercellular junctions, the mechanism has not been elucidated fully. Here, we report that TNF enhances the solubility of JAM-A in Triton X-100 and increases the amount of Triton-soluble JAM-A dimers at the cell surface but does not change the total levels of cellular JAM-A. Thus we hypothesized that TNF causes the redistribution of JAM-A from the junctions to the cell surface and that junction disassembly is sufficient to account for JAM-A redistribution. Intriguingly, however, even after complete disassembly of the junctions (with EDTA and trypsin), higher levels of JAM-A are detectable at the cell surface (by FACS analysis) in cells that had been previously incubated in the presence of TNF than in its absence. Thus we propose that TNF causes not only the disassembly of JAM-A from the junctions and its subsequent redistribution to the cell surface but also its dispersal in such a way that JAM-A becomes more easily accessible to the antibodies used for FACS analysis. Finally, we evaluated whether soluble fibronectin might attenuate the effects of TNF on JAM-A, as some inflammatory conditions are associated with the depletion of plasma fibronectin. We found that fibronectin reduces the effect of TNF on the disassembly of JAM-A, but not on its dispersal, thus further stressing that disassembly and dispersal can be functionally dissociated.

Expression of junctional adhesion molecule-A prevents spontaneous and random motility.

Junctional adhesion molecule-A (JAM-A) is a cell-surface glycoprotein that localizes to intercellular junctions and associates with intracellular proteins via PSD95-Dlg-ZO1-binding residues. To define the functional consequences of JAM-A expression, we have produced endothelial cells from JAM-A-deficient mice. We report here that the absence of JAM-A enhanced spontaneous and random motility. In turn, the enhanced motility of JAM-A-negative cells was abrogated either on transfection of exogenous JAM-A or on treatment with inhibitors of glycogen synthase kinase-3beta (GSK-3beta). In addition, in JAM-A-positive cells, motility was enhanced on inactivation of protein kinase Czeta (PKCzeta), which is an inhibitor of GSK-3beta. Although these findings suggested that JAM-A might inhibit GSK-3beta, we found that expression per se of JAM-A did not change the levels of inactive GSK-3beta. Thus, JAM-A expression may regulate effectors of motility that are also downstream of the PKCzeta/GSK-3beta axis. In support of this view, we found that JAM-A absence increased the number of actin-containing protrusions, reduced the stability of microtubules and impaired the formation of focal adhesions. Notably, all the functional consequences of JAM-A absence were reversed either on treatment with GSK-3beta inhibitors or on transfection of full-length JAM-A, but not on transfection of a JAM-A deletion mutant devoid of the PSD95-Dlg-ZO1-binding residues. Thus, by regulating cytoskeletal and adhesive structures, JAM-A expression prevents cell motility, probably in a PSD95-Dlg-ZO1-dependent manner.