Opposite effects of bone morphogenetic protein-2 and transforming growth factor-beta1 on osteoblast differentiation.

Several members of the transforming growth factor-beta (TGF-beta) superfamily have been demonstrated to play regulatory roles in osteoblast differentiation and maturation, but the mechanisms by which they act on different cells at different developmental stages remain largely unknown. We studied the effects of TGF-beta1 and bone morphogenetic protein-2 (BMP-2) on the differentiation/maturation of osteoblasts using the murine cell lines MC3T3-E1 and C3H10T1/2. BMP-2 induced or enhanced the expression of the osteoblast differentiation markers alkaline phosphatase (ALP) and osteocalcin (OC) in both cells. In contrast, TGF-beta1 was not only unable to induce these markers, but it dramatically inhibited BMP-2-mediated OC gene expression and ALP activity. In addition, TGF-beta1 inhibited the ability of BMP-2 to induce MC3T3-E1 mineralization. TGF-beta1 did not sensibly modify the increase of Osf2/Cbfa1 gene expression mediated by BMP-2, thus demonstrating that the inhibitory effect of TGF-beta1 on osteoblast differentiation/maturation mediated by BMP-2 was independent of Osf2/Cbfa1 gene expression. Finally, it is shown that TGF-beta1 does not affect BMP-2-induced Smad1 transcriptional activity in the mesenchymal pluripotent cells studied herein. Our data indicate that in vitro BMP-2 and TGF-beta1 exert opposite effects on osteoblast differentiation and maturation.

Inhibition of carcinogen induced c-Ha-ras and c-fos proto-oncogenes expression by dietary curcumin.

BACKGROUND: We investigated the chemopreventive action of dietary curcumin on 7,12-dimethylbenz(a)anthracene (DMBA)-initiated and 12,0-tetradecanoylphorbol-13-acetate (TPA)-promoted skin tumor formation in Swiss albino mice. Curcumin, a yellow coloring matter isolated from roots of Curcuma longa Linn, is a phenolic compound possessing antioxidant, free radical scavenger, and antiinflammatory properties. It has been shown by previously reported work that TPA-induced skin tumors were inhibited by topical application of curcumin, and curcumin has been shown to inhibit a variety of biological activities of TPA. Topical application of curcumin was reported to inhibit TPA-induced c-fos, c-jun and c-myc gene expression in mouse skin. This paper reports the effects of orally administered curcumin, which was consumed as a dietary component at concentrations of 0.2 % or 1 %, in ad libitum feeding. RESULTS: Animals in which tumors had been initiated with DMBA and promoted with TPA experienced significantly fewer tumors and less tumor volume if they ingested either 0.2% or 1% curcumin diets. Also, the dietary consumption of curcumin resulted in a significantly decreased expression of ras and fos proto-oncogenes in the tumorous skin, as measured by enhanced chemiluminesence Western blotting detection system (Amersham). CONCLUSIONS: Whereas earlier work demonstrated that topical application of curcumin to mouse skin inhibited TPA-induced expression of c-fos, c-jun and c-myc oncogenes, our results are the first to show that orally consumed curcumin significantly inhibited DMBA- and TPA-induced ras and fos gene expression in mouse skin.

Inhibitory effect of dietary curcumin on skin carcinogenesis in mice.

Laboratory animal model studies have suggested that curcumin may play an important role in inhibiting the process of carcinogenesis. Curcumin, the yellow pigment that is obtained from rhizomes of the plant Curcuma longa Linn (Family Zingiberaceae), is commonly used as a spice and food coloring agent. The present study was designed to investigate the chemopreventive action of dietary curcumin on 7,12-dimethylbenz[a]anthracene (DMBA)-initiated and 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted skin tumor formation in male Swiss ablino mice. At 6 weeks of age, groups of animals were fed the standard (modified AIN-76 A) diet or a diet containing 1% curcumin. At 8 weeks of age, all animals, except those in the vehicle (acetone)-treated groups, received 100 microg of DMBA dissolved in 100 microl of acetone in a single application to the skin of the back. From 1 week after DMBA application, tumor promoter (2.5 microg of TPA dissolved in 100 microl of acetone) was applied to the same areas on mouse skin twice a week for 26 weeks. All groups continued on their respective dietary regimen until the termination of the experiment. The results indicate that dietary administration of curcumin significantly inhibited the number of tumors per mouse (P < 0.05) and the tumor volume (P < 0.01). The percentage of tumor-bearing mice tended to be lower in the mice on the curcumin diet than those on the standard diet. There was no difference in growth between mice of the standard and 1% curcumin groups. The results indicate the safety and the anti-carcinogenic effect of curcumin in mice.

HR 720, a novel angiotensin receptor antagonist inhibits the angiotensin II-induced trophic effects, fibronectin release and fibronectin-EIIIA+ expression in rat aortic vascular smooth muscle cells in vitro.

The aim of this study was to evaluate the direct trophic effects of angiotensin II (AII) on rat vascular smooth muscle cells obtained from a single cellular isolate. Cell volume, protein synthesis, fibronectin (FN) release and FN-EIIIA+ mRNA isoform expression were analyzed in parallel. The effects of HR 720, a novel AT1 angiotensin receptor antagonist with some AT2 receptor affinity, were compared with those of selective AT1 antagonist EXP 3174. Both HR 720 and EXP 3174 inhibited in a concentration-dependent manner the maximum increase in cell volume induced by 10(-9) M Sar1-All (IC50 = 0.49 x 10(-9) M and 0.79 x 10(-9) M, respectively). Maximum [3H]leucine incorporation was also achieved at 10(-9) M All. HR 720 blocked the increase in protein synthesis with potency similar to EXP 3174; the respective IC50 values were 1.04 x 10(-9) M and 1.36 x 10(-9) M. All dose-dependently increased FN release, which was also equally inhibited by about 50% with both compounds at 10(-6) M. Furthermore, All enhanced FN-EIIIA+ mRNA in rat vascular smooth muscle cells (VSMC), which indicated a modulation of FN isoform expression which was inhibited by angiotensin II antagonists. In conclusion, All induced parallel and concentration-dependent increases in cell volume, protein synthesis, FN release and FN-EIIIA+ mRNA expression in vascular smooth muscle cells. These effects appeared to be essentially mediated by AT1 receptor stimulation as indicated by the equal inhibitory effects of HR 720 and EXP 3174.

Effects of subchronic treatment with trandolapril and enalapril on cardiovascular morphologic alterations in the aged spontaneously hypertensive rat with heart failure.

The effects of a 3-month treatment period with the angiotensin-converting enzyme (ACE) inhibitors trandolapril (0.3 mg/kg/day, p.o.) and enalapril (10 mg/kg/day, p.o.) on hemodynamics, cardiac hypertrophy, and vascular structures were examined in old spontaneously hypertensive rats (SHRs) (24 months at the end of treatment) presenting with congestive heart failure. During the course of treatment, the mortality rate was lower in the two treated groups than in the control group. At the end of treatment, serum ACE activity was inhibited by 63 and 33% by trandolapril and enalapril, respectively, but the decrease in blood pressure they induced was not significant. The atrial natriuretic factor(ANF) plasma levels and cyclic GMP urine excretion were about 10-fold and 3-fold higher, respectively, in old SHRs than in old Wistar rats. These values were markedly decreased by both ACE inhibitors. The ventricular hypertrophy was greatly decreased by both compounds (-24% by trandolapril and -26% by enalapril). In the aorta, the media hypertrophy was significantly decreased and nuclear density increased to a similar extent by both ACE inhibitors. In the mesenteric artery, trandolapril treatment induced a complete regression of the media hypertrophy and a marked decrease in extracellular matrix surface. In addition, the collagen network appeared less dissociated in the treated animals. Similarly the nuclear density was increased and the surface of cell nuclei was decreased by trandolapril. Enalapril appeared much less potent on these parameters. These data demonstrate that treatment with trandolapril of aged SHRs presenting with heart failure results in an increase in survival of the animals and a marked regression of cardiac and vascular hypertrophy.(ABSTRACT TRUNCATED AT 250 WORDS)

Analogy between fibrinogen and casein. Effect of an undecapeptide isolated from kappa-casein on platelet function.

A large number of similarities have previously been noted between the blood and milk clotting phenomena [Jollès, P. (1975) Mol. Cell. Biochem. 7, 73-85; Jollès, P. & Henschen, A. (1982) Trends Biochem. Sci. 7, 325-328]: some analogous features have also been found between fibrinogen and kappa-casein. In this connection, the effect of a natural and a synthetic peptide derived from kappa-casein on platelet function was studied: the undecapeptide Met-Ala-Ile-Pro-Pro-Lys-Lys-Asn-Gln-Asp-Lys (residues 106----116 of cow kappa-casein) inhibited both aggregation of ADP-treated platelets and binding of 125I-fibrinogen to ADP-treated platelets: its behaviour was similar to that of the structurally related C-terminal dodecapeptide of human fibrinogen gamma-chain.

Importance of the interaction between plasminogen and fibrin for plasminogen activation by tissue-type plasminogen activator.

The potentiating effect of fibrin monomer on plasminogen activation by tissue-type plasminogen activator is much more important with lys-plasminogen than with mini-plasminogen (which lacks the high affinity lysine-binding site important for binding to fibrin). Furthermore, this potentiating effect is totally abolished when lys-plasminogen is eluted from fibrin by the addition of 1 mM epsilon-amino caproic acid. Binding does however not seem to be the only condition required since it was found that fragment D is a much stronger potentiator of the activation of plasminogen by tissue-type plasminogen activator than fragment E although plasminogen binds to both fragment D and fragment E. Furthermore, fragment E has the same effect on the activation of lys-and mini-plasminogen by tissue-type plasminogen activator. Therefore, it is suggested that binding of plasminogen to fibrin involves a conformational change in the plasminogen molecule, facilitating its activation by tissue-type plasminogen activator.

Interactions of platelets with standard heparin and low molecular weight fractions.

The availability of fibrinogen receptors on platelets after ADP stimulation, was investigated in order to analyze platelet hyperaggregability induced by heparin. Unfractionated heparin increased the binding of fibrinogen on ADP-treated platelets. The results varied according to both the donor platelets and the kind of heparin preparation used. Beef lung heparin was more active than porcine intestinal mucosa heparin (P less than 0.001). Low molecular weight (LMW) heparin fractions however did not significantly increase the binding of fibrinogen to ADP-treated platelets. The effect of standard heparin and LMW heparin on the aggregation of normal platelets induced by the addition of plasma from patients with heparin-induced immune thrombocytopenia was also studied. Concerning heparin-induced immune thrombocytopenia we have shown that the plasma cofactor present in some patient plasma may induce platelet aggregation both in the presence of standard-heparin and in the presence of LMW heparin fractions. Therefore, one has to be careful when replacing standard heparin by LMW heparin or heparinoids since each patient may react differently.