Biological influence of Ca/P ratio on calcium phosphate coatings by sol-gel processing.

The objective of this work has been to develop low temperature sol-gel glass coatings to modify the substrate surface and to evaluate their bioactivity and biocompatibility. Glasses, based on SiO2·CaO·P2O5, were synthesized by the sol-gel technique using tetraethyl orthosilicate, calcium nitrate tetrahydrate and triethyl phosphate as precursors of SiO2, CaO and P2O5, respectively. Those materials, still in the sol phase, have been used to coat substrates by means of the dip-coating technique. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) has been used for characterize coatings and a microstructural analysis has been obtained using scanning electron microscopy (SEM). The potential applications of the coatings in the biomedical field were evaluated by bioactivity and biocompatibility tests. The coated substrate was immersed in simulated body fluid (SBF) for 21days and the hydroxyapatite deposition on its surface was subsequently evaluated via SEM-EDXS analysis, as an index of bone-bonding capability. In order to study the cell behavior and response to our silica based materials, prepared via the sol-gel method, with various Ca/P ratio and coating substrate, we have used the human osteoblast-like U2OS cell line.

Oxidative stress and ERK1/2 phosphorylation as predictors of outcome in hepatocellular carcinoma patients treated with sorafenib plus octreotide LAR.

We reported a relevant activity of the combination between sorafenib and octreotide long-acting release (LAR) in advanced hepatocellular carcinoma (HCC) patients. In this work, we have studied if oxidative stress in both serum and peripheral blood mononuclear cells (PBMC) and pERK activation status in PBMC could be predictive of response. In the 20 responsive patients, the decrease of reactive oxygen species levels was already detectable after 10 days (T10) from the beginning of sorafenib administration, and this effect was enhanced by the combined treatment with sorafenib+octreotide LAR (T21). This effect correlated with the modulation of superoxide dismutase (SOD) activity (physiological scavenger of O(2-)) and of serum nitric oxide (NO) levels. Sorafenib alone induced an increase of about 40% of NO levels and of about two-fold of SOD activity in responsive patients, and both effects were significantly potentiated by the combined treatment. We found a gradual reduction of Erk1/2 activity, as evaluated by cytofluorimetric analysis, in 15 responsive patients reaching about 50% maximal decrease at T21. On the other hand, in 17 resistant patients, Erk1/2 activity was about 80% increased at T21. The determination of both the oxidative stress status and pERK activity in PBMC has high value in the prediction of response to sorafenib+octreotide therapy in HCC patients.

[Evaluation in vitro of the cardiotoxic effects of 5-fluorouracil for the prevention of cardiovascular damage in health workers occupationally exposed]. / Valutazione in vitro degli effetti cardiotossici da 5-fluorouracile per la prevenzione dei danni cardiovascolari negli operatori sanitari professionalmente esposti.

The occupational exposure to antineoplastic drugs in health care workers determines a risk of absorption through inhalation of vapors or skin contact with drops. Even if many data confirm the cardiotoxicity of anthracyclines, is not clear the evidence of cytotoxicity of 5-Fluorouracil, thoug in a percent of patients receiving this chemotherapy, there is the presence of heart pain, aspecific ECG disorders and induction of coronary disease. This experimental study wants to analyze on the H9c2 cardiomyocyte cell model the effects of 5-Fluorouracil, commonly used in hospital realities of the South Italy, for the prevention of the possible cardiovascular damage in workers occupationally exposed.

Adenylate cyclase/cAMP pathway downmodulation counteracts apoptosis induced by IFN-alpha in human epidermoid cancer cells.

We have reported previously that interferon-alpha (IFN-alpha) induces apoptosis that is counteracted by an epidermal growth factor (EGF) --> Ras --> extracellular signal-regulated kinase (ERK)-dependent survival response in human epidermoid cancer KB cells. We have studied the effects of the cytokine on the cAMP-dependent pathway in these cells. A decrease in the intracellular cAMP levels was recorded in KB cells treated with IFN-alpha, whereas forskolin induced an increase in the production of cAMP that was reduced in the presence of IFN-alpha, suggesting a reduction in the activity of adenylate cyclase (AC) induced by IFN-alpha. These effects were paralleled by significant change in the expression of some AC catalytic subunit(s) and by reduction in the activity of protein kinase A (PKA). 8-Br-cAMP completely antagonized the reduction of PKA activity induced by IFN-alpha, whereas PKA inhibitor KT5720 enhanced the reduction of the enzyme activity induced by IFN-alpha. We have found that IFN-alpha induced a decrease in cAMP response element binding protein (CREB) phosphorylation without changes in its total expression. The concomitant treatment with IFN-alpha and 8-Br-cAMP potentiated and KT5720 counteracted apoptosis induced by IFN-alpha alone. In conclusion, these data suggest that the decrease in AC/cAMP pathway activity is a survival response to the apoptosis induced by IFN-alpha. Therefore, this pathway could represent a target to enhance the antitumor activity of IFN-alpha.

Differentiation of H9c2 cardiomyoblasts: The role of adenylate cyclase system.

The adenylate cyclase (AC)/cAMP/cAMP-dependent protein kinase pathway controls many biological phenomena. The molecular mechanisms by which cAMP induces alternative commitment towards differentiation or proliferation are not still completely known. The differentiation of myoblast cell lines into myocytes/myotubes represents a well-established model of skeletal muscle differentiation. We analyzed the AC/cAMP pathway during terminal differentiation of H9c2 myoblasts. When cultured in low-serum containing medium, H9c2 myoblasts exit the cell cycle and differentiate into myocytes/myotubes. A key step of this process is the expression of myogenin, an essential transcription factor for the terminal differentiation into myocytes. During this phenomenon we observed a decrease in both cAMP levels and AC activity, which suggests a functional negative role of cAMP on the differentiation process of H9c2 cells. 8-Br-cAMP and other cAMP-elevating agents, such as forskolin, IBMX, and isoproterenol, negatively affected skeletal muscle differentiation of H9c2 myoblasts. Both AC activity down-regulation and intracellular cAMP reduction were accompanied by significant variations in the levels of membrane proteins belonging to the AC system (AC catalytic subunit, G(alphai-1), G(alphas)). The functional relationship between intracellular cAMP content and protein levels of AC system is discussed.

Treatment of v-Ki-ras-transformed SVC1 cells with low retinoic acid induces malignancy reversion associated with ras p21 down-regulation.

The effect of nontoxic, low concentrations (10(-8) M) of retinoic acid (RA) for a relatively long time (28 days) on a Kirsten ras-virus transformed cell line (Ki-SVC1), derived from the rat seminal vesicle epithelium, was investigated. In these experimental conditions, the cell treatment with RA induced a decrease of the proliferation rate, apoptosis and a marked reduction of both anchorage-independent growth and tumorigenicity. These biological responses were either preceded or associated with important changes in adenylate cyclase/protein kinase C signaling pathways, the activation of important apoptosis-linked genes and a marked decrease of the v-Ki-ras p21 protein. The significance of these findings is discussed.

UBPY: a growth-regulated human ubiquitin isopeptidase.

The ubiquitin pathway has been implicated in the regulation of the abundance of proteins that control cell growth and proliferation. We have identified and characterized a novel human ubiquitin isopeptidase, UBPY, which both as a recombinant protein and upon immunoprecipitation from cell extracts is able to cleave linear or isopeptide-linked ubiquitin chains. UBPY accumulates upon growth stimulation of starved human fibroblasts, and its levels decrease in response to growth arrest induced by cell-cell contact. Inhibition of UBPY accumulation by antisense plasmid microinjection prevents fibroblasts from entering S-phase in response to serum stimulation. By increasing or decreasing the cellular abundance of UBPY or by overexpressing a catalytic site mutant, we detect substantial changes in the total pattern of protein ubiquitination, which correlate stringently with cell proliferation. Our results suggest that UBPY plays a role in regulating the overall function of the ubiquitin-proteasome pathway. Affecting the function of a specific UBP in vivo could provide novel tools for controlling mammalian cell proliferation.

ras oncogene-induced transformation of a rat seminal vesicle epithelial cell line produces a marked increase of adenylate cyclase and protein kinase C activities.

Cells transformed by Kirsten murine sarcoma virus (Ki-MSV) have basal adenylate cyclase activity (AC) higher than control cells and comparable level of forskolin-stimulated AC activity. Moreover, a higher protein kinase C (PKC) activity was found to be present in the transformed cells. The molecular mechanism underlying the increase of AC activity was investigated. Our findings strongly suggest that this biochemical event is due to a marked decrease of the alpha i negative control of the enzyme, even though the alpha i of transformed cells appears to possess fully functional domains interacting with both the effector enzyme and the agonist-activated receptor.