Abstract. Electrical signals elicited by integrin interaction with ECM components and theft role in neurite outgrowth were studied in two clones (N1 and N7) isolated from 41A3 murine neuroblastoma cell line. Although the two clones similarly adhered to fibronectin (FN) and vitroncctin O/N), this adhesion induced neurite outgrowth in NI but not in N7 cells. Patch clamp recordings in whole cell configuration showed that, upon adhesion to FN or VN but not to platelet factor 4 (PF4), NI cells undergo a marked (---20 mV) hyperpolarization of the resting potential (Vr, t) that occurred within the first 20 min after cell contact with ECM, and persisted for •1 h before reverting to the time zero values. This hyperpolarization was totally absent in N7 cells. A detailed analysis of the molecular mechanisms involved in N1 and N7 cell adhesion to ECM substrata was performed by using antibodies raised against the FN receptor and synthetic peptides variously competing with the FN or VN binding to integrin receptors (GRGDSP and GRGESP). Antibodies, as well as GRGDSP, abolished adhesion of N1 and N7 clones to FN and VN, revealing a similar implication of integrins in the adhesion of these clones to the ECM proteins. However, these anti-adhesive treatments, while ineffective on V,~, of N7 cells, abolished in N1 cells the FN-or VN-induced hyperpolarization and neurite outgrowth, that appeared therefore strictly associated and integrin-mediated phenomena. The nature of this association was deepened through a comparative analysis of the integrin profiles and the ion channels of N1 and N7 cells. The integrin immunoprecipitation profile resulted very similarly in the two clones, with only minor differences concerning the aV containing complexes. Both clones possessed Ca 2+ and K + delayed rectifier (KDR) channels, while only N1 cells were endowed with inward rectifier K + (Kit) channels. The latter governed the Vr~, and, unlike KDR channels, were blocked by Ba 2+ and Cs +. By moving patched cells in contact with FN-coated beads, it was shown that Km channel activation was responsible for the FN-mediated hyperpolarization of V,~. Treatment with Pertuxis toxin (PTX) abolished this hyperpolarization and neurite outgrowth, indicating that a G protein is interposed between integrins and Km channels and that the activation of these channels is required for neuritogenesis. In fact, the block of Km channels by Cs ÷ abolished both hyperpolarization and neurite outgrowth, provided that the cation was supplied during the first two hours after N1 cell contact with FN. This Cs+-sensitive commitment time for neuritogenesis coincided with the time length of the FNinduced hyperpolarization.

During the 2002-2003 austral summer field season, aerosol samples were collected at a coastal (Terra Nova Bay--Northern Victoria Land) and an inland site (Dome C--East Antarctic Plateau). The sampling was carried out by stacked filter units made up of two filters at different porosity (5.0 and 0.4 microm at Terra Nova Bay and 3.0 and 0.4 microm at Dome C), able to roughly separate a coarse from a fine fraction. At Dome C, a further investigation on aerosol size distribution was performed by an inertial impactor able to collect aerosol particles on 8 size classes (from 10 to 0.4 microm). Atomic Force Microscopy was applied to the filter collecting the finer fraction in both sites in order to assess the real cut-off value of the filter sandwich apparatus and to reconstruct the volume size distribution. At the employed flow conditions, the real cut-off value was revealed to be about one third with respect to the filter nominal porosity in both stations. The size distribution plots showed a bimodal distribution with a mode centered around 0.22 microm in both the sites and a second broader mode which is centered between 0.3 microm and 1.2 microm diameter at Terra Nova Bay and shifted toward higher values (centred around 1.0 microm diameter) at Dome C. Each filter was analysed for the main and trace ionic components allowing evaluation of the contributions of primary and secondary aerosol sources at the two sites as a function of the particle size class. The coastal site is mainly affected by primary and secondary marine inputs: the sea spray contribution (Na+, Mg2+, Cl- and ssSO4(2-)) is dominant (77% w/w) in the coarse fraction whereas the biogenic source (methanesulfonate and nssSO4(2-)) prevails (67.5% w/w) in the fine fraction. In this fraction a significant contribution (15.5% w/w) is provided by ammonium likely to be related to surrounding penguin colonies. Dome C atmosphere is characterised by fine particles arising from secondary sources and long-range transport processes. The main component in the fine and coarse fractions at Dome C is sulfate whose nssSO4(2-) represents the 99.5% and the 92.3%(w/w) in fine and coarse fraction, respectively. The observed agreement between nssSO4(2-) and methanesulfonate temporal profiles in the fine fraction demonstrates that biogenic emissions dominate the inland background aerosol. Results from the sampling by the 8-stage impactor at Dome C are presented here: chloride and nitrate are mainly deposited on the 10-2.1 microm stages while the highest sulfate concentration was found in the submicrometric fraction which turned out to be the most acidic. Such a distribution is able to prevent nitrate and chloride re-emission as gaseous HCl and HNO3 in the 10-2.1 microm stages, arising from the exchange reaction between chloride and nitrate salts and sulfuric acid. Moreover, the concentration peak observed for nitrate in coarser fractions is probably related also to the formation of hygroscopic NH4NO3 particles and nitrate adsorption on sea salt particles.

The biological significance of the almost constant presence of macrophages in the tumoral microenvironment is an issue debated by several authors. The major difficulty in understanding the role played by tumor-associated macrophages (TAMs) in tumor progression is due to the contrasting effects of TAMs found in different studies. In addition, there is a limited information on which of the many biological activities expressed by TAMs are critical in inducing stimulatory or inhibitory effect on tumor growth. The aim of our study was: (a) to explore to what extent cyclo-oxygenase-2 (COX-2) in TAMs associated with human melanoma is expressed at different stages of tumor progression; and (b) to explore whether COX-2 expression in TAMs is stimulated by melanoma cells. In order to answer this question, we determined COX-2 positive TAMs associated with cutaneous melanocytic nevi, in situ, invasive and metastatic melanoma. In addition, we investigated whether COX-2 is expressed in peritoneal thioglycollate-elicited macrophages after co-cultivation with murine B16 melanoma cells. We found that COX-2-positive TAMs, as revealed by immunohistochemical analysis, were rare in common nevi and "dysplastic nevi", but present in a high percentage in in situ and thin melanoma. COX-2-positive TAMs were also found in more advanced tumors and metastatic melanoma, although at a significantly lower percentage in these latter. The in vitro protocol revealed that COX-2 was expressed in peritoneal macrophages upon contact with B16 murine melanoma cells, but not with normal murine fibroblasts. On the whole, the results of in vivo and in vitro studies suggest that COX-2 expressed in TAMs appears to act as an effective biomarker of melanoma progression, and melanoma cells themselves might stimulate COX-2 in macrophages.

The aim of this study was to investigate whether tumor cells as well as tumor-associated macrophages (TAMs) contribute to the generation of protease activities essential to tumor cell invasiveness, such as matrix metalloproteinase 2 and 9 (MMP-2 and MMP-9), and the urokinase-type plasminogen activator (uPA) and uPA receptor (uPAR). We found that the enhanced invasiveness through Matrigel-coated filters of B16 murine melanoma cells stimulated with IFNc was associated with an higher expression of uPAR and MMP-9 in these cells. Moreover, treatment with anti-MMP-9 or anti-uPAR monoclonal antibodies abrogated the increase of invasiveness in IFNcstimulated melanoma cells, suggesting a cooperation of uPA system and MMP-9 in cytokine-stimulated invasiveness. Invasiveness through Matrigel was also enhanced in B16 melanoma cells exposed to a medium conditioned by TAMs, represented in our experimental model by thioglycollate-elicited macrophages co-cultivated with melanoma cells. Macrophages isolated from these co-cultures were found to express higher levels of uPAR and MMP-9 compared to macrophage cultures alone, and the pro-invasive activity of the co-culture-conditioned medium was abrogated by anti-MMP-9 monoclonal antibodies, but not anti-uPAR monoclonal antibodies. Furthermore, the enhanced uPAR and MMP-9 expression in macrophages cocultivated with tumor cells seems a rather specific phenomenon, generated through a cell-to-cell contact mechanism. On the whole, our data point to a cooperation between tumor cells and macrophages elicited by tumor cells themselves in generating key enzymes essential in the promotion of tumor invasiveness, such as uPAR and MMP-9.Keywords Murine melanoma cells Á Macrophages Á Cell invasiveness Á Matrix metalloproteinase 2 (MMP-2) and 9 (MMP-9) Á Urokinase-type plasminogen activator (uPA) and uPA receptor (uPAR)

An enhanced apoptosis and a reduced angiogenesis are associated with the inhibition of lung colonisation in animals fed an n-3 polyunsaturated fatty acid-rich diet injected with a highly metastatic murine melanoma line Antonella Mannini, Nadja Kerstin, Lido Calorini, Gabriele Mugnai and Salvatore Ruggieri* Both epidemiological and experimental studies indicate that dietary n-3 PUFA inhibit carcinogenesis and tumour growth. Metastatic diffusion has also been found to be affected in animals fed diets containing purified n-3 PUFA or fish oil. In the present study, we investigated whether the metastatic diffusion of a highly metastatic variant (F10-SR cells) isolated from the B16 melanoma F10 line was affected by feeding host animals a diet containing 5 % fish oil. In these animals, compared with those fed a diet containing 5 % maize oil, there was a reduced number of metastatic pulmonary colonies. The immunohistochemical analysis of appropriate markers revealed that the antimetastatic effect of dietary n-3 PUFA was not related to a reduction of proliferation, but rather to an enhanced apoptotic activity. The reduction of von Willebrand factor immunoreactivity found in pulmonary colonies of F10-SR cells grown in fish oil-fed animals indicates that a decrease of angiogenesis contributes to the antimetastatic effect of dietary n-3 PUFA. This conclusion stands in spite of the higher expression of vascular endothelial growth factor observed in pulmonary colonies grown in fish oil-fed animals.