Transforming growth factor-beta1 inhibits the growth of primary adult rat hepatocyte cultures by increasing cAMP levels

We investigated the mechanisms of transforming growth factor-beta1 (TGF-beta1) inhibition on transforming growth factor-alpha (TGF-alpha)-induced DNA synthesis and proliferation in primary cultures of adult rat hepatocytes. TGF-alpha (1.0 ng/ml) produced a 4.2-fold elevation of DNA synthesis during 3 h of culture and a 1. 2-fold increase in nucleus number (proliferation) during 4 h of culture. TGF-beta1 dose dependently inhibited the TGF-alpha-induced hepatocyte DNA synthesis and proliferation: half-maximal inhibition occurred at a TGF-beta1 concentration of 0.08 ng/ml. The inhibitory effects of 1.0 ng/ml TGF-beta1 were almost completely reversed by adenylate cyclase inhibitors, 2,4-dideoxyadenosine (10(-6) M), and somatostatin (3 x 10(-7) M), or by a specific inhibitor of protein kinase A, H-89 (N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride; 10(-7) M). In addition, while TGF-alpha did not affect the basal cellular adenosine 3',5'-monophosphate (cAMP) levels, TGF-beta1 was found to produce dose-dependent increases in cellular cAMP levels. The cAMP-elevating effects of TGF-beta1 were also reversed by 2,4-dideoxyadenosine (10(-6) M), and somatostatin (3 x 10(-7) M), but not by H-89 (10(-7) M). The present results suggest that the specific mechanisms involved in the growth inhibitory effect of TGF-beta1 on TGF-alpha-induced hepatocyte DNA synthesis and proliferation are via stimulation of adenylate cyclase, which increases intracellular cAMP and subsequently activates protein kinase A.     

Transforming growth factor-beta 1-induced collagen production in cultures of cardiac fibroblasts is the result of the appearance of myofibroblasts

Transforming growth factor-beta 1 (TGF-beta 1), which appears in high concentrations in fibrotic cardiac tissue, is a potent inductor of tissue collagen deposition and of the differentiation of fibroblasts to myofibroblasts. It is accepted that TGF-beta 1 is a potent stimulator of collagen secretion by fibroblasts. The aim of the present study was to determine which type of cells, fibroblasts and/or myofibroblasts are stimulated, in terms of collagen production, by TGF-beta 1. Therefore, using cultures of second-passage rat cardiac fibroblasts, we investigated the dose- (0.003-15 ng/ml) and time-dependence (2-48 h) of the TGF-beta 1-induced effects on collagen production and on the appearance of myofibroblasts, as estimated by the presence of alpha-smooth muscle actin (alpha-SMA; a marker of myofibroblasts). The reversibility of the TGF-beta 1-stimulated effects was also studied. The dose- and time-dependent stimulation of collagen production was closely associated with the induction of alpha-SMA. TGF-beta 1 did not change the cell phenotype or increase collagen production in rat cardiac fibroblasts cultures after a long incubation (24-28 h) at low concentrations (< 1 ng/ml), or after a short incubation (2-4 h) at high concentrations (1-15 ng/ml). However, after a long incubation at high concentrations, TGF-beta 1 changed the cell phenotype and increased collagen production in these cultures through the differentiation of fibroblasts to myofibroblasts. A maximal increase of collagen production (two-fold, p < 0.001) was observed after incubation of fibroblasts with 15 ng/ml TGF-beta 1 for 48 h. Under these conditions, alpha-SMA was increased by 3.5-fold (p < 0.001) and second-passage cultures of fibroblasts and their offspring in the next passage consisted mainly of myofibroblasts. The stimulation of collagen by 15 ng/ml TGF-beta 1 for 48 h was irreversible. In fact, additional incubation of these second-passage TGF-beta 1-stimulated cultures without TGF-beta 1 for 2 days did not decrease the high activity of collagen production. Moreover, the third-passage offspring of these TGF-beta 1-stimulated fibroblasts cultured without TGF-beta 1 also showed a higher production of collagen compared with control fibroblasts. Furthermore, the increased collagen production in the third-passage fibroblast offspring of the second-passage TGF-beta 1-stimulated fibroblasts could not be further stimulated by TGF-beta 1. Thus, the activity of collagen production in TGF-beta 1-stimulated cultures and in their next passage offspring is not sensitive to TGF-beta 1. Our data suggest that TGF-beta 1-stimulated collagen production in cultures of adult rat cardiac ventricular fibroblasts cannot be explained by a direct stimulation of collagen production, either in fibroblasts or in myofibroblasts. Instead, TGF-beta 1 induces differentiation of fibroblasts to myofibroblasts, the latter having a higher activity for collagen production than the former.     

Transforming growth factor-beta 1 does not relate to hypertension in pre-eclampsia

1. Pre-eclampsia is a human disease of pregnancy characterized by high blood pressure, proteinuria and end-organ damage, if severe. Pre-eclampsia is thought to be related to changes in early placental development, with the formation of a shallower than normal placental bed. 2. Transforming growth factor (TGF)-beta1 is a multifunctional fibrogenic growth factor involved in immune regulation that is elevated in some populations with a high risk of hypertensive end-organ disease related to increases in endothelin release. Transforming growth factor-beta1 is also an important factor in placental implantation. Alterations in TGF-beta1 may be related to abnormal placental development in early pregnancy and, thus, are a candidate for the development of hypertension in pre-eclampsia. 3. The aim of the present study was to examine the placental distribution and serum concentration of TGF-beta1 in patients with pre-eclampsia compared with normal pregnancy. 4. Patients with pre-eclampsia (n = 12) were compared with patients with normal pregnancy (n = 14). Transforming growth factor-beta1 was determined by TGF-beta1 Max ELISA (Promega, Madsion, WI, USA) after serum dilution (1/150) and acid activation. Placental distribution was determined by immunostaining with TGF-beta1 (Santa Cruz, Santa Cruz, CA, USA; 20 ng/mL) and the villi and decidual trophoblast were scored for intensity and extent of staining. 5. Patients with pre-eclampsia had a mean gestational age of 36 weeks, whereas those with a normal pregnancy had a mean gestational age of 39.0 +/- 0.4 weeks. There was no difference in TGF-beta1 concentration between the two groups (mean (+/-SEM) 27.1 +/- 1.0 vs 26.4 +/- 0.7 pg/mL for normal pregnancy and pre-eclampsia, respectively; P = 0.73, Mann-Whitney U-test). There was no correlation between systolic or diastolic blood pressure and TGF-beta1 concentration (regression analysis P = 0.4 and 0.2). Immunostaining was absent in the villous trophoblast cells and endovascular and extravillous trophoblast of term placentas. 6. Although TGF-beta1 is present in trophoblast cells in early pregnancy during placental development, TGF-beta1 concentrations were not increased in the placenta at term in pre-eclampsia and there was no correlation between blood pressure and serum TGF-beta1, suggesting that TGF-beta1 does not play a role in the development of late gestation pre-eclampsia and hypertension.     

白果内酯刺激大鼠星形胶质细胞GDNF和VEGF表达(英文)

目的:观察白果内酯对大鼠星形胶质细胞GDNF和VEGF表达的影响。方法:应用半定量PCR了解大鼠星形胶质细胞分别经不同浓度白果内酯(0,5,15,50,100μmol·L~(-1))作用12、24和48h后细胞内GDNF和VEGF mRNA的变化,同时应用免疫组化了解经50μmol·L~(-1)作用24h后细胞内GDNF和VEGF蛋白的变化。结果:大鼠星形胶质细胞经50μmol·L~(-1)白果内酯作用12h后,细胞内GDNF和VEGF mRNA水平开始显著增高,经50μmol·L~(-1)作用24h后细胞胞浆内可见明显的VEGF和GDNF蛋白表达。结论:白果内酯可能通过诱导星形胶质细胞GDNF和VEGF的表达对神经细胞起保护作用。     

Enhanced expression of contractile endothelin ET(B) receptors in rat coronary artery after organ culture

Endothelin-1 is a potent vasoconstrictor mediating its effects via two receptor subtypes, the endothelin type A (ET(A)) preferentially situated on smooth muscle cells, mediating vasoconstriction and endothelin type B (ET(B)) mainly located on endothelial cells, mediating vasodilatation. In cardiovascular disease and in organ culture in vitro, endothelin ET(B) receptors are up-regulated on smooth muscle cells. The objectives of the present study were to characterise the endothelin receptor-induced vasoconstriction and quantify the endothelin receptor mRNA levels and immunoreactivity in fresh and cultured rat coronary arteries. We demonstrate that endothelin-1 induces strong and equal concentration-dependent contractions in fresh and cultured segments from the left anterior descending coronary artery. Sarafotoxin 6c, an endothelin ET(B) receptor agonist, had negligible effect in fresh arteries but produced significant vasoconstriction after organ culture. The endothelin ET(B) receptor mRNA level and the receptor protein immunoreactivity were increased, whereas the level of endothelin ET(A) receptor mRNA was down-regulated but not its receptor protein immunoreactivity after organ culture. Pharmacological inhibition of endothelium-derived dilatory mediators did not influence endothelin ET(A) or ET(B) receptor-mediated vasoconstriction in fresh segments. In cultured arteries, inhibition of endothelial vasodilators potentiated the effect of sarafotoxin 6c. In conclusion, endothelin ET(B) receptor stimulation in cultured coronary arteries elicits vasoconstriction. This is likely not related to endothelial dysfunction with putative loss of its vasodilator components, but rather explained by the up-regulation of contractile endothelin ET(B) receptors on smooth muscle cells.     

Transforming growth factor-beta1 upregulation is independent of angiotensin in paraquat-induced lung fibrosis

Transforming growth factor-beta1 (TGF-beta1) contributes to the fibrosis of injured organs. Angiotensin II (Ang II) is an inducer of TGF-beta1 in cells of the heart and kidneys, and the regulation of TGF-beta1 by Ang II has not yet been confirmed in lung tissue. We evaluated the role of TGF-beta1 and its relationship with Ang II in paraquat-induced lung fibrosis. Adult male Sprague-Dawley rats were treated intraperitoneally with paraquat (20mg/kg) or saline in the control group. On days 1, 3, 7, and 21 after paraquat treatment, TGF-beta1 and collagen gene expressions, TGF-beta1 protein, angiotensin-converting enzyme (ACE) activity, Ang II, and hydroxyproline contents were measured in lung tissue. Lung TGF-beta1 mRNA expression progressively increased and reached a peak on day 7 after paraquat treatment. Increases in TGF-beta1 mRNA expression and TGF-beta1 levels preceded the onset of increased collagen I mRNA expression and hydroxyproline contents. c-myc mRNA expressions were inversely correlated with TGF-beta1 protein levels in paraquat-treated lungs. Lung ACE activity decreased after paraquat administration and the decrement was maximal on day 7. Lung Ang II concentrations immediately decreased after paraquat administration and the values were not related to TGF-beta1 levels. We conclude that TGF-beta1 is upregulated and contribute to the paraquat-induced lung fibrosis and this effect is independent of the renin-angiotensin system.     

Glucose-mediated transforming growth factor-beta1 release in human mesothelial cells is endothelin independent

Glucose and mechanical forces have been shown to be potent stimuli for mesothelial endothelin-1 release promoting profibrotic processes during peritoneal dialysis. We studied the osmolarity-induced and physical stress-induced effects on transforming growth factor-beta1 (TGF-beta1) release in human peritoneal mesothelial cells (HPMC), and analyzed whether a combined endothelin-A/endothelin-B receptor antagonist is able to mitigate HPMC TGF-beta1 release. D-Glucose and glycerol were used to analyze the impact of osmolarity on HPMC TGF-beta1 release. A cellular model of non-laminar fluid shear stress and cellular stretch was used to analyze the effects of physical forces. To neutralize the endothelin effects, a combined endothelin-A/endothelin-B receptor antagonist (LU 302 872) was chosen. Glucose, but not glycerol, increased mesothelial TGF-beta1 release in a concentration-dependent and time-dependent manner (P < 0.05 versus controls). Mechanical forces alone had no effect on mesothelial TGF-beta release. Combining fluid shear stress with high glucose medium led to a 30% increase (P = 0.019), and cellular stretch to a 34% increase (P = 0.075) in TGF-beta release compared with glucose stress alone. The combined endothelin-A/endothelin-B receptor antagonist had no impact on the mesothelial TGF-beta release. In conclusion, HPMC TGF-beta1 release by glucose and mechanical stress seems not to be related to the activity of the peritoneal endothelin system - at least in our in vitro model.     

Cell-specific regulation of human aryl hydrocarbon receptor expression by transforming growth factor-beta(1)

Previous studies showed that TGF-beta down-regulates aryl hydrocarbon (AhR) expression in human lung carcinoma cells A549. Here we analyzed the molecular mechanisms by which TGF-beta modulates AhR expression. A 5799-nucleotide 5'-flanking region of human AhR gene was isolated. Transient transfection studies of full-length (hAhRP) and deletion promoter constructs indicate the requirement of a cis-regulatory element encompassing -1980 to -1892 for full constitutive activity. Basal hAhRP activity occurs in a cell-specific manner; human hepatoma HepG2 cells possess a 10-fold higher activity compared with A549 cells. TGF-beta exerts cell-specific effects on hAhRP activity. Treatment of cells with 100 pM TGF-beta leads to a 50% inhibition in A549 and a 3-fold induction in HepG2 cells. Deletion mutagenesis identified a TGF-beta-responsive sequence containing a functional conserved Smad-binding element. Transient overexpression of Smad 2, 3, and 4 indicates that these signal transducers modulate hAhRP activity. The down-regulation of AhR by TGF-beta is modulated by 5'-TG-3'-interacting factor (TGIF). Transient overexpression of TGIF in MDA-MB231 and HepG2 cells led to inhibition of hAhRP activity and a similar decrease of AhR mRNA expression. Our findings indicate that Smad proteins are involved in the cell-specific regulation of AhR expression by TGF-beta.     

The inhibitory effects of aqueous extract of Magnolia officinalis on human mesangial cell proliferation by regulation of platelet-derived growth factor-BB and transforming growth factor-beta1 expression

Mesangial cell (MC) proliferation, mediated by platelet-derived growth factor (PDGF)-BB, transforming growth factor (TGF)-beta1, and cyclin-dependent kinases (CDK), is the common feature of glomerulosclerosis. Magnolia officinalis, stem bark of Machilus thunbergii S., has multiple pharmacological effects. In this study, we investigated the influence of aqueous extract of Magnolia officinalis on MC proliferation, DNA synthesis, and expression of PDGF-BB, TGF-beta1, CDK1, CDK2, and CDK4 in fetal bovine serum (FBS)-activated human MC. Magnolia officinalis inhibited the MC proliferation, DNA synthesis, and the expression of PDGF-BB, CDK1, and CDK2 gene and CDK1, CDK2, and TGF-beta1 protein. These results suggest that the inhibitory effect of Magnolia officinalis on MC proliferation may be mediated by regulation of PDGF-BB and TGF-beta1expressions and by modulation of CDK1 and CDK2 expression.     

PKC and MAPK signalling pathways regulate vascular endothelin receptor expression

Up-regulation of vascular endothelin type A (ET(A)) and type B (ET(B)) receptors are implicated in the pathogenesis of cardiovascular disease. Culture of arteries has been shown to induce similar receptor alterations and has therefore been suggested as a suitable method for in detail delineation of the regulation of endothelin receptors. We hypothesize that protein kinase C (PKC) and mitogen-activated kinases (MAPK) are involved in the regulation of endothelin receptors. Porcine coronary arteries were studied before and after 24 h of culture, using in vitro pharmacology, real-time PCR and immunofluorescence techniques. Sarafotoxin 6c and endothelin ET-1 were used to examine the endothelin ET(A) and ET(B) receptor effects. The involvement of PKC and MAPK in the receptor regulation was examined by culture in the presence of antagonists. Organ culture resulted in increased sarafotoxin 6c and endothelin-1 contractions, endothelin ET(A) and ET(B) receptor immunofluorescence staining intensities and endothelin ET(B), but not ET(A), receptor mRNA levels. The general PKC inhibitors, bisindolylmaleimide I (10 microM) or Ro-32-0432 (10 microM), inhibited these effects. Also, the increase in sarafotoxin 6c contraction, endothelin ET(B) receptor and mRNA levels and endothelin ET(A) and ET(B) immunofluorescence staining intensities were inhibited by MAPK inhibitors for extracellular signal related kinases 1 and 2 (ERK1/2), PD98059 (10 microM), C-jun terminal kinase (JNK), SP600125 (10 microM), but not by p38 MAPK, SB203580 (10 microM). In conclusion, PKC and MAPK seem to be involved in the regulation of endothelin receptor expression in porcine coronary arteries. Inhibiting these intracellular signal transduction pathways may provide a future therapeutic target for hindering the development of vascular endothelin receptor changes in cardiovascular disease.     

Altered expression of basement membrane-related molecules in rat brain pericyte, endothelial, and astrocyte cell lines after transforming growth factor-beta1 treatment

The basement membrane at the blood-brain barrier (BBB) plays important roles in maintaining the structure and function of capillary vessels. The BBB is constructed from endothelial cells, astrocytes and pericytes, but their interactions in the formation or maintenance of basement membrane have not been established. Transforming growth factor-beta1 (TGF-beta1) is known to increase fibronectin in brain capillary basement membrane with deposition of beta-amyloid. We previously reported that the mRNA level of alpha-smooth muscle actin in a brain capillary pericyte cell line TR-PCT1 was increased by treatment with TGF-beta1. In this study, expression of mRNAs encoding basement membrane-related molecules in TR-PCT1, a rat endothelial cell line TR-BBB13, and a type 2 astrocyte cell line TR-AST4 was evaluated by RT-PCR. The effects of TGF-beta1 on expression of basement membrane-related genes in these cell lines were also examined. Fibronectin, MMP-9, tPA, TIMP-1, and PAI-l in TR-PCT1 were higher than in TR-BBB13 and TR-AST4. In TR-PCT1 treated with TGF-beta1, collagen type IV, PAI-1, and MMP-9 were increased, and TIMP-2 was reduced. The change in PAI-1 mRNA was faster than those in MMP-9, TIMP-2, collagen type IV mRNAs. These results suggest that pericytes may be key cells in the maintenance of the basement membrane at the BBB.     

Transforming growth factor-beta: a molecular target for the future therapy of glioblastoma

The median survival of patients with glioblastoma treated by surgery, radiotherapy and chemotherapy is in the range of 12 months. These limits in the efficacy of current treatment modalities call for the development of novel therapeutic approaches targeting the specific biological features of this type of cancer. Glioblastomas are a rich source of immunosuppressive molecules which may interfere with immune recognition and rejection as well as clinical strategies of active immunotherapy. The most prominent glioblastoma-associated immunosuppressant is the cytokine, transforming growth factor (TGF)-beta, a multifunctional cytokine which not only interferes with multiple steps of afferent and efferent immune responses, but also stimulates migration, invasion and angiogenesis. The complex regulation of TGF-beta bioavailability includes its synthesis as a proprotein, proteolytic processing by furin-like proteases, assembly in a latent complex, and finally liberation from latency by multiple effector mechanisms, a process collectively referred to as activation. Several in vitro paradigms and rodent glioma models have been used to demonstrate that the antagonism of TGF-beta holds promise for the treatment of glioblastoma, employing antisense strategies, inhibition of pro-TGF-beta processing, scavenging TGF-beta by decorin, or blocking TGF-beta activity by specific TGF-beta receptor (TGF-betaR) I kinase antagonists. Moreover, the local application of TGF-beta(2) antisense oligonucleotides is currently evaluated in a randomized clinical trial for recurrent malignant glioma. In summary, we propose that TGF-beta-antagonistic treatment strategies are among the most promising of the current innovative approaches for glioblastoma, particularly in conjunction with novel approaches of cellular immunotherapy and vaccination.     

乙醇抑制原代大鼠星形细胞神经营养因子的基因表达

为了阐明乙醇中毒对神经系统损害的机理 ,用0 .5- 5.0 g· L-1浓度的乙醇处理原代培养的 CD新生大鼠大脑皮层星形细胞 ,用反转录 PCR和Northern印迹杂交方法同时测定神经营养因子( NGF)的基因表达水平 .结果显示 0 .5g·L-1乙醇在染毒 2 4 h后 ,NGF m RNA水平开始降低 ,5.0 g· L-1在染毒 48或 72 h后 ,NGF m RNA水平与对照组比较降低了 50 % - 58% .结果表明 ,乙醇中毒在体外可降低新生大鼠星形细胞 NGF m RNA的生成 ,这种作用可干扰神经元与胶质细胞间的正常交互作用并可能与胚胎发育期乙醇接触导致的神经病理改变有关 .     

Transforming growth factor-β1 gene polymorphisms associated with chronic obstructive pulmonary disease in Chinese population

AIM: To determine the frequencies of polymorphism and haplotype in the transforming growth factor-beta 1 (TGF-beta1) gene promoter in the Chinese population and to investigate the susceptibility of this population to chronic obstructive pulmonary disease (COPD). METHODS: The target fragments of the TGF-beta1 gene promoter were amplified and analyzed by polymerase chain reaction-restriction fragment length polymorphism technique in 84 COPD patients and 97 age- and sex-matched healthy controls. The test for Hardy-Weinberg equilibrium was performed using HWE program of the LINKUTIL package and statistical analysis was carried out with the SPSS statistical package. An expectation maximization algorithm was used for the pairwise linkage disequilibrium test and haplotype analysis. RESULTS: More carriers of the -800A allele, or fewer carriers of the -509T allele, were detected in the COPD patients compared with the non-symptomatic control subjects [for the -800A allele, 29.8% vs 14.4%, respectively, Chi2=6.257, degrees of freedom (df)=1, P=0.012; for the -509T allele, 27.3% vs 44.3%, respectively, Chi2=5.582, df=1, P=0.018]. The prevalence of the -800A allele was significantly higher in the COPD patients than in control subjects (P=0.009), whereas the frequency of the -509T allele was significantly higher in control subjects than in the COPD patients (P=0.008). In addition, this distribution tendency for the -800A or -509T allele was similar in heavy smokers (smoking history >20 pack years); (number of packs of cigarettes per day multiplied by the number of years of smoking) Chi2=7.235, P=0.007, and Chi2=5.636, P=0.018, respectively). The linkage disequilibrium was found between -800 G-A and -509 C-T (D>0.60, P<0.0001), and the frequency of the AC haplotype, consisting of the least common base at -800 and the most common base at -509, was significantly higher in patients with COPD than in controls (0.056 vs 0.021, P<0.05). CONCLUSIONS: The single nucleotide polymorphism (SNP) in the TGF-beta1 gene promoter might be associated with COPD, and the -800A/-509C haplotype is possibly one of the susceptibility factors for COPD.     

Alkaloid production by leaf organ, root organ and cell suspension cultures of Cinchona ledgeriana

The alkaloids produced by leaf organ, root organ and root suspensions of two varieties of Cinchona ledgeriana have been determined quantitatively by HPLC. In contrast to previous findings, the root organs and root suspensions yielded quinine and quinidine. The root cells release alkaloids into the suspension medium.     

Transforming growth factor-beta1 stimulates heme oxygenase-1 expression via the PI3K/Akt and NF-kappaB pathways in human lung epithelial cells

A previous report showed that transforming growth factor-β1 (TGF-β1) can induce heme oxygenase-1 (HO-1) expression, attenuate cellular injury, and maintain tissue homeostasis. In this study, we investigated the involvement of phosphoinositide-3-OH-kinase (PI3K)/Akt and the nuclear factor-κB (NF-κB) signaling pathway in TGF-β1-induced HO-1 expression in human lung epithelial cells (A549). Treatment of A549 cells with TGF-β1 caused HO-1 to be expressed in a concentration- and time-dependent manner. Treatment of A549 cells with LY 294002 (2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one, a PI3K inhibitor), an Akt inhibitor, and the dominant negative mutant of Akt (Akt DN) inhibited TGF-β1-induced HO-1 expression and HO-1-luciferase activity. Stimulation of cells with TGF-β1 caused an increase in Akt phosphorylation in a time-dependent manner, which was inhibited by wortmannin and LY 294002 (PI3K inhibitors). In addition, treatment of A549 cells with Bay 117082 ((E)-3-[4-methylphenylsulfonyl]-2-propenenitrile, an IκB phosphorylation inhibitor), pyrrolidine dithiocarbamate (PDTC, an NF-κB inhibitor), and the dominant negative mutant of IκB (IκBM) inhibited TGF-β1-induced HO-1 expression and HO-1-luciferase activity. Treatment of A549 cells with TGF-β1-induced IκB kinase /β (IKK/β) phosphorylation, IκB phosphorylation, IκB degradation, p65 Ser536 phosphorylation, and κB-luciferase activity. The TGF-β1-mediated increases in IKK/β phosphorylation, p65 Ser536 phosphorylation, and κB-luciferase activity were inhibited by LY 294002, an Akt inhibitor, and Akt DN. Taken together, these results suggest that the PI3K/Akt dependent IKK/β/NF-κB signaling pathway plays an important role in TGF-β1-induced HO-1 expression in A549 cells.