Human ucMSCs seeded in a decellularized kidney scaffold attenuate renal fibrosis by reducing epithelial-mesenchymal transition via the TGF-ß/Smad signaling pathway.

BACKGROUND: Renal fibrosis occurs largely through epithelial-mesenchymal transition (EMT). This study explored the beneficial effects of a human umbilical cord mesenchymal stem cell-loaded decellularized kidney scaffold (ucMSC-DKS) on renal fibrosis in a rodent model of post-transplantation renal failure, and the underlying mechanism. METHODS: Rat-derived DKSs were examined after preparation, and then recellularized with human ucMSCs to prepare cell-loaded patches. A rat model of renal failure was established after subtotal nephrectomy (STN). The cell patches were transplanted to remnant kidneys. Changes in renal function, histology, EMT, and proteins related to the transforming growth factor-ß (TGF-ß)/Smad signaling pathway in the remnant kidneys were examined 8 weeks after surgery, compared with non-cell patch controls. RESULTS: The DKSs were acellular and porous, with rich cytokine and major extracellular matrix components. The ucMSCs were distributed uniformly in the DKSs. Renal function was improved, renal fibrosis and EMT were reduced, and the TGF-ß/Smad signaling pathway was inhibited compared with controls at 8 weeks after ucMSC-DKS patch transplantation. CONCLUSIONS: The ucMSC-DKS restores renal function and reduces fibrosis by reducing EMT via the TGF-ß/Smad signaling pathway in rats that have undergone STN. It provides an alternative for renal fibrosis treatment.

The BMP-SMAD pathway mediates the impaired hepatic iron metabolism associated with the ERFE-A260S variant.

The erythroferrone (ERFE) is the erythroid regulator of hepatic iron metabolism by suppressing the expression of hepcidin. Congenital dyserythropoietic anemia type II (CDAII) is an inherited hyporegenerative anemia due to biallelic mutations in the SEC23B gene. Patients with CDAII exhibit marked clinical variability, even among individuals sharing the same pathogenic variants. The ERFE expression in CDAII is increased and related to abnormal erythropoiesis. We identified a recurrent low-frequency variant, A260S, in the ERFE gene in 12.5% of CDAII patients with a severe phenotype. We demonstrated that the ERFE-A260S variant leads to increased levels of ERFE, with subsequently marked impairment of iron regulation pathways at the hepatic level. Functional characterization of ERFE-A260S in the hepatic cell system demonstrated its modifier role in iron overload by impairing the BMP/SMAD pathway. We herein described for the first time an ERFE polymorphism as a genetic modifier variant. This was with a mild effect on disease expression, under a multifactorial-like model, in a condition of iron-loading anemia due to ineffective erythropoiesis.

Glial cell line-derived neurotrophic factor (GDNF) mediates hepatic stellate cell activation via ALK5/Smad signalling.

OBJECTIVE: Although glial cell line-derived neurotrophic factor (GDNF) is a member of the transforming growth factor-ß superfamily, its function in liver fibrosis has rarely been studied. Here, we investigated the role of GDNF in hepatic stellate cell (HSC) activation and liver fibrosis in humans and mice. DESIGN: GDNF expression was examined in liver biopsies and sera from patients with liver fibrosis. The functional role of GDNF in liver fibrosis was examined in mice with adenoviral delivery of the GDNF gene, GDNF sgRNA CRISPR/Cas9 and the administration of GDNF-blocking antibodies. GDNF was examined on HSC activation using human and mouse primary HSCs. The binding of activin receptor-like kinase 5 (ALK5) to GDNF was determined using surface plasmon resonance (SPR), molecular docking, mutagenesis and co-immunoprecipitation. RESULTS: GDNF mRNA and protein levels are significantly upregulated in patients with stage F4 fibrosis. Serum GDNF content correlates positively with α-smooth muscle actin (α-SMA) and Col1A1 mRNA in human fibrotic livers. Mice with overexpressed GDNF display aggravated liver fibrosis, while mice with silenced GDNF expression or signalling inhibition by GDNF-blocking antibodies have reduced fibrosis and HSC activation. GDNF is confined mainly to HSCs and contributes to HSC activation through ALK5 at His39 and Asp76 and through downstream signalling via Smad2/3, but not through GDNF family receptor alpha-1 (GFRα1). GDNF, ALK5 and α-SMA colocalise in human and mouse HSCs, as demonstrated by confocal microscopy. CONCLUSIONS: GDNF promotes HSC activation and liver fibrosis through ALK5/Smad signalling. Inhibition of GDNF could be a novel therapeutic strategy to combat liver fibrosis.

SUMO protease SENP1 acts as a ceRNA for TGFBR2 and thus activates TGFBR2/Smad signaling responsible for LPS-induced sepsis.

This study aims to explore the roles and related mechanisms of SUMO protease SENP1 in sepsis. Here, RNA-sequencing assay showed that SENP1 was significantly increased in human umbilical vein endothelial cells (HUVECs) with LPS treatment. Gene set enrichment analysis (GSEA) of RNA-sequencing dataset revealed that a positive enrichment of inflammation signatures was observed in HUVECs with SENP1 3'UTR overexpression. Further functional annotation analysis revealed that SENP1 3'UTR overexpression was positively correlated with TGFBR2 signaling pathway. Mechanistically, TGFBR2 was identified as a ceRNA (competing endogenous RNA) target of SENP1 and the downstream effectors Smad2/3 were also overexpressed in HUVECs with SENP1 3'UTR overexpression. Injection of SENP1 siRNA following LPS treatment attenuated LPS-induced sepsis, evidenced by the downregulation of IL-2 and TNF-α secretion and prolonged the overall survival of septic mice. Consistent results were obtained in vitro. Additionally, TGFBR2 overexpression partially abrogated SENP1 siRNA-mediated inhibition on LPS-induced sepsis. Thus, these results suggest that SENP1 promotes sepsis via activating the TGFBR2 signaling.

BMP-7/Smad expression in dedifferentiated Schwann cells during axonal regeneration and upregulation of endogenous BMP-7 following administration of PTH (1-34).

PURPOSE:: To determine the expression and distribution of bone morphogenetic protein (BMP)-7 and related molecules during peripheral nerve regeneration and to assess whether administration of parathyroid hormone (PTH) drug (1-34) potentiates the intrinsic upregulation of BMP-7/Smad signaling. METHODS:: The rat sciatic nerves were crushed with an aneurysm clip resulting in axonal degeneration. In the normal nerve, and at 1, 2, 4, and 8 weeks after injury, BMP-7, BMP receptors, p-Smad 1/5/8, and Noggin, the endogenous BMP antagonist, were evaluated. Additionally, the distribution of BMP-7 was assessed by fluorescent double immunostaining. In vitro studies were also performed to examine the effect of BMP-7 and PTH (1-34) administration on rat Schwann cells (SCs). RESULTS:: Aneurysm clip made reliable animal model of the nerve injury with recovery at 8 weeks after the injury. BMP-7/Smad protein and mRNA were significantly upregulated on axon-SCs units at 1 week after injury, and this upregulated expression was maintained for 4 weeks. Besides, significant upregulation of Noggin's expression was observed on axon-SCs units at 2 weeks after injury. Moreover, fluorescent double immunostaining showed co-localization between expression of BMP-7 and p75NTR during axonal regeneration. In the in vitro study, administration of BMP-7 induced significant proliferation of SCs. Application of PTH (1-34) upregulated BMP-7 on SCs. DISCUSSION/CONCLUSION:: BMPs were reported to be involved in protection and recovery after injury as well as in neurogenesis. Our current study showed that BMP/Smad signaling molecules were upregulated on dedifferentiated SCs after peripheral nerve injury and that administration of BMP-7 increased SC viability in vitro. These results suggested that axonal regeneration could be induced via upregulation of endogenous BMP-7 on SCs by PTH (1-34) administration.

MiR-181a promotes epithelial to mesenchymal transition of prostate cancer cells by targeting TGIF2.

OBJECTIVE: Prostate cancer is the most commonly diagnosed cancer, and metastatic prostate cancer often leads to poor outcomes for patients. During the metastasis processes, cancer cells acquire a migratory and invasive phenotype. Epithelial to mesenchymal transition (EMT) has been implicated in multiple processes of prostate cancer development including migration, chemoresistance, and carcinogenesis. PATIENTS AND METHODS: Expressions of miR-181a in prostate tumor samples and cancer cells were measured by qRT-PCR. Epithelial or mesenchymal markers were detected by Western blot. Nuclear translocation of Smad 2/3 was measured by immunostaining of prostate cancer cells. RESULTS: In this study, we report an oncogenic role of microRNA-181a in prostate cancer cells and patients. MiR-181a is upregulated in metastatic prostate tumor samples compared with primary prostate tumors. Interestingly, we found that overexpression of miR-181a promotes prostate cancer cell migration and invasion. Moreover, we observed that overexpression of miR-181a contributes to an epithelial to mesenchymal transition phenotype in prostate cancer cells: the epithelial marker, E-cadherin was downregulated, and mesenchymal markers, N-cadherin, vimentin, and snail were upregulated. Consistently, the phosphorylation of Smad 2/3 and the nuclear localization of Smad 2/3 were increased by miR-181a expression. We identified that TGIF2 - a repressor of the Smad pathway - is a direct target of miR-181a in prostate cancer cells. Importantly, restoration of TGIF2 in miR-181a overexpressing prostate cancer cells inhibited the Smad pathway and EMT processes. CONCLUSIONS: This research identifies a molecular mechanism for microRNA-mediated cancer metastasis and improvement novel therapeutic avenue for metastatic prostate cancer patient treatments.

The GSK3ß inhibitor BIS I reverts YAP-dependent EMT signature in PDAC cell lines by decreasing SMADs expression level.

The Yes-associated protein, YAP, is a transcriptional co-activator, mediating the Epithelial to Mesenchymal Transition program in pancreatic ductal adenocarcinoma (PDAC). With the aim to identify compounds that can specifically modulate YAP functionality in PDAC cell lines, we performed a small scale, drug-based screening experiment using YAP cell localization as the read-out. We identified erlotinib as an inducer of YAP cytoplasmic localization, an inhibitor of the TEA luciferase reporter system and the expression of the bona fide YAP target gene, Connective Tissue Growth Factor CTGF. On the other hand, BIS I, an inhibitor of PKCδ and GSK3ß, caused YAP accumulation into the nucleus. Activation of ß-catenin reporter and interfering experiments show that inhibition of the PKCδ/GSK3ß pathway triggers YAP nuclear accumulation inducing YAP/TEAD transcriptional response. Inhibition of GSK3ß by BIS I reduced the expression levels of SMADs protein and reduced YAP contribution to EMT. Notably, BIS I reduced proliferation, migration and clonogenicity of PDAC cells in vitro, phenocopying YAP genetic down-regulation. As shown by chromatin immunoprecipitation experiments and YAP over-expressing rescue experiments, BIS I reverted YAP-dependent EMT program by modulating the expression of the YAP target genes E-cadherin, vimentin, CTGF and of the newly identified target, CD133. In conclusion, we identified two different molecules, erlotinib and BIS I, modulating YAP functionality although via different mechanisms of action, with the second one specifically inhibiting the YAP-dependent EMT program in PDAC cell lines.

Bergenin ameliorates diabetic nephropathy in rats via suppressing renal inflammation and TGF-ß1-Smads pathway.

CONTEXT: Diabetic nephropathy (DN) is a serious complication of diabetes. Bergenin (BEG) was previously confirmed to be effective in treating type 2 diabetes in rats. OBJECTIVE: The objective of this study was to investigate the effects of BEG on renal function in diabetic rats, and meanwhile explore the molecular mechanism. METHODS: DN was induced in rats by a single intraperitoneal injection of streptozotocin. The renal function was evaluated by serum creatinine (SCr), blood urea nitrogen (BUN), urinary albumin and renal histopathology. The proliferation of mesangial cells (MCs) was assayed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H tetrazolium bromide. The production of inflammatory cytokines was detected by ELISA kits, and the levels of Smads were measured by western blotting. RESULTS AND CONCLUSION: In DN rats, there were significantly increased levels of SCr, BUN, urinary albumin, plasma glucose and renal index. The histological changes in diabetic kidney revealed noteworthy focal mesangial matrix expansion. In vitro experiment, high glucose markedly promoted MCs proliferation. However, treatment with BEG obviously normalized these functional parameters, improved diabetic histological changes in vivo and inhibited MCs' proliferation in vitro. Moreover, the levels of tumor necrosis factor-alpha, interleukin-1 (IL-1) and IL-6 in BEG-treated renal tissue and MCs were both reduced. Finally, it showed that BEG markedly reduced transforming growth factor-ß1 (TGF-ß1) production, down-regulated p-Smad2/3 expression and promoted Smad7 expression both in vivo and in vitro. In conclusion, BEG exerts the effective protective role against kidney injuries of diabetic rat, in which the underlying mechanisms are associated with reducing renal inflammation and blocking TGF-ß1-Smads pathway.

Aluminum trichloride inhibits osteoblast mineralization via TGF-ß1/Smad signaling pathway.

Osteoporosis is a major global public health problem. Aluminum (Al) exposure inhibits osteoblast mineralization and induces osteoporosis. However, the exact mechanism is not fully understood. The transforming growth factor ß1 (TGF-ß1)/Smad pathway is a major signaling cascade in regulating osteoblast mineralization. To investigate whether TGF-ß1/Smad signaling pathway was involved in the Al-induced inhibition of osteoblast mineralization, osteoblasts were cultured and exposed to different concentrations of aluminum trichloride (AlCl3) (containing 0, 0.01, 0.02 and 0.04 mg/mL Al(3+)) for 24 h. We found that mineralized matrix nodules, mRNA expressions of alkaline phosphatase (ALP), type I collagen (Col I), TGF-ß1, TGF-ß type I receptor, TGF-ß type II receptor and Smad4, protein expressions of TGF-ß1 and p-Smad2/3, Smad2/3/4 trimeric complex were all decreased, whereas the mRNA expressions of Smad7 were increased in the AlCl3-treated groups compared with those in control. In conclusion, these results indicated that AlCl3 inhibited osteoblast mineralization via TGF-ß1/Smad signaling pathway in rat osteoblasts. Our findings could provide novel insights into the mechanisms of action of AlCl3 in osteoporosis.

BMP4 inhibits myogenic differentiation of bone marrow-derived mesenchymal stromal cells in mdx mice.

BACKGROUND AIMS: Bone marrow-derived mesenchymal stromal cells (BMSCs) are a promising therapeutic option for treating Duchenne muscular dystrophy (DMD). Myogenic differentiation occurs in the skeletal muscle of the mdx mouse (a mouse model of DMD) after BMSC transplantation. The transcription factor bone morphogenic protein 4 (BMP4) plays a crucial role in growth regulation, differentiation and survival of many cell types, including BMSCs. We treated BMSCs with BMP4 or the BMP antagonist noggin to examine the effects of BMP signaling on the myogenic potential of BMSCs in mdx mice. METHODS: We added BMP4 or noggin to cultured BMSCs under myogenic differentiation conditions. We then injected BMP4- or noggin-treated BMSCs into the muscles of mdx mice to determine their myogenic potential. RESULTS: We found that the expression levels of desmin and myosin heavy chain decreased after treating BMSCs with BMP4, whereas the expression levels of phosphorylated Smad, a downstream target of BMP4, were higher in these BMSCs than in the controls. Mdx mouse muscles injected with BMSCs pretreated with BMP4 showed decreased dystrophin expression and increased phosphorylated Smad levels compared with muscles injected with non-treated BMSCs. The opposite effects were seen after pretreatment with noggin, as expected. CONCLUSIONS: Our results identified BMP/Smad signaling as an essential negative regulator of promyogenic BMSC activity; inhibition of this pathway improved the efficiency of BMSC myogenic differentiation, which suggests that this pathway might serve as a target to regulate BMSC function for better myogenic differentiation during treatment of DMD and degenerative skeletal muscle diseases.

Ski prevents TGF-ß-induced EMT and cell invasion by repressing SMAD-dependent signaling in non-small cell lung cancer.

Epithelial-mesenchymal transition (EMT) is a key event in cancer metastasis, which confers cancer cells with increased motility and invasiveness, and EMT is characterized by loss of epithelial marker E-cadherin and gain of mesenchymal marker N-cadherin. Transforming growth factor-ß (TGF-ß) signaling is a crucial inducer of EMT in various types of cancer. Ski is an important negative regulator of TGF-ß signaling, which interacts with SMADs to repress TGF-ß signaling activity. Although there is accumulating evidence that Ski functions as a promoter or suppressor in human types of cancer, the molecular mechanisms by which Ski affects TGF-ß-induced EMT and invasion in non-small cell lung cancer (NSCLC) are not largely elucidated. In the present study, we investigated the mechanistic role of Ski in NSCLC metastasis. Ski was significantly reduced in metastatic NSCLC cells or tissues when compared with non-metastatic NSCLC cells or tissues. Moreover, following TGF-ß stimulation Ski-silenced A549 cells had more significant features of EMT and a higher invasive activity when compared with A549 cells overexpressing Ski. Mechanistically, Ski-silenced and overexpressed A549 cells showed an increase and a reduction in the SMAD3 phosphorylation level, respectively. This was supported by plasminogen activator inhibitor-1 (PAI-1) promoter activity obtained in Ski-silenced and overexpressed A549 cells. However, after treatment of SIS3 (inhibitor of SMAD3 phosphorylation) followed by TGF-ß1 stimulation, we did not observe any effect of Ski on TGF-ß-induced EMT, and invasion in Ski-silenced and overexpressed A549 cells. In conclusion, our findings suggest that Ski represses TGF-ß-induced EMT and invasion by inhibiting SMAD-dependent signaling in NSCLC.

Elemene, the essential oil of Curcuma wenyujin, inhibits osteogenic differentiation in ankylosing spondylitis.

OBJECTIVE: To explore the effects of Elemene, the essential oil of Curcuma wenyujin, on Bone morphogenetic protein/drosophila mothers against decapentaplegic proteins (BMP/SMADs) signal pathway in ankylosing spondylitis (AS) fibroblasts. METHODS: Hip joint capsules were obtained from AS patients (n=10) receiving total hip replacement. Healthy hip joint capsules from patients with hip fracture (n=10) receiving surgery were included as a control. Primary fibroblast cell lines were established from these tissue samples. Fibroblasts were incubated with Elemene for 48 hours. The protein expression was detected by Western blot. The mRNA expression was detected by real-time fluorescent quantitative polymerase chain reaction (PCR). RESULTS: The results showed that the expression of proteins including SMAD1, pSMAD1, SMAD4 and Runt-related transcription factor 2 (RUNX2), and mRNA of RUNX2, which were over-expressed in AS fibroblasts were decreased in the AS fibroblasts cultured in medium with Elemene. CONCLUSIONS: Ele could have a hand in anti-osteogenic differentiation of AS fibroblasts by inhibiting the BMP/SMADs signal pathway and subsequently blocking expression of ossification marker genes RUNX2 that initiate the osteogenic differentiation.

MAPK inhibitors differently modulate TGF-ß/Smad signaling in HepG2 cells.

The aim of this study was to investigate the mitogen-activated protein kinase (MAPK) pathway, which crosstalk with TGF-ß/Smad signaling via linker phosphorylation of Smad2/3 to promote hepatocarcinogenesis. After DEN-induced hepatocellular carcinoma (HCC) in rats showed increased phosphorylation of JNK1/2, p38, and ERK1/2, we next antagonized TGF-ß1-induced phosphorylation of JNK1/2, p38, ERK1/2, Smad2/3 signaling in HepG2 cells using SP600125, SB203580, and PD98059, respectively. Cell proliferation and invasion were assessed by MTT assay and transwell invasion chambers, respectively. Smad2/3, Smad4, and Smad7 expressions and PAI-1 messenger RNA (mRNA) transcription were measured by using immuno-precipitation/immuno-blotting and real-time RT-PCR, respectively. All the MAPK-specific inhibitors suppressed cell invasion, while all but PD98059 suppressed cell proliferation. Both SP600125 and SB203580 blocked pSmad2C/L and oncogenic pSmad3L. PD98059 blocked pSmad2L but had no effect on elevated pSmad2C and oncogenic pSmad3L. All but PD98059 blocked Smad2/3/4 complex formation and restored Smad7 expression, while all the three MAPK-Specific inhibitors repressed PAI-1 mRNA transcription. Both SP600125 and SB203580 inhibited HepG2 cells' proliferation and invasion by blocking oncogenic pSmad3L and Smad2/3/4 complex formation. PD98059 repressed PAI-1 mRNA by an unknown mechanism.

Conditionally immortalized human pancreatic stellate cell lines demonstrate enhanced proliferation and migration in response to IGF-I.

Pancreatic stellate cells (PSCs) play a key role in the dense desmoplastic stroma associated with pancreatic ductal adenocarcinoma. Studies on human PSCs have been minimal due to difficulty in maintaining primary PSC in culture. We have generated the first conditionally immortalized human non-tumor (NPSC) and tumor-derived (TPSC) pancreatic stellate cells via transformation with the temperature-sensitive SV40 large T antigen and human telomerase (hTERT). These cells proliferate at 33°C. After transfer to 37°C, the SV40LT is switched off and the cells regain their primary PSC phenotype and growth characteristics. NPSC contained cytoplasmic vitamin A-storing lipid droplets, while both NPSC and TPSC expressed the characteristic markers αSMA, vimentin, desmin and GFAP. Proteome array analysis revealed that of the 55 evaluated proteins, 27 (49%) were upregulated ≥3-fold in TPSC compared to NPSC, including uPA, pentraxin-3, endoglin and endothelin-1. Two insulin-like growth factor binding proteins (IGFBPs) were inversely expressed. Although discordant IGFBP-2 and IGFBP-3 levels, IGF-I was found to stimulate proliferation of both NPSC and TPSC. Both basal and IGF-I stimulated motility was significantly enhanced in TPSC compared to NPSC. In conclusion, these cells provide a unique resource that will facilitate further study of the active stroma compartment associated with pancreatic cancer.

PKCε is a negative regulator of PVAT-derived vessel formation.

RATIONALE: Vessel formation is a crucial event in tissue repair after injury. Thus, one assumption of innovative therapeutic approaches is the understanding of its molecular mechanisms. Notwithstanding our knowledge of the role of Protein Kinase C epsilon (PKCε) in cardio-protection and vascular restenosis, its role in vessel progenitor differentiation remains elusive. OBJECTIVE: Given the availability of PKCε pharmacological modulators already tested in clinical trials, the specific aim of this study is to unravel the role of PKCε in vessel progenitor differentiation, with implications in vascular pathology and vasculogenesis. METHODS AND RESULTS: Mouse Peri-Vascular Adipose Tissue (PVAT) was used as source of mesenchymal vessel progenitors. VEGF-induced differentiation of PVAT cells down-regulates both PKCε and p-PAK1 protein expression levels. PKCε overexpression and activation: i) reduced the expression levels of SMA and PECAM in endothelial differentiation of PVAT cells; ii) completely abrogated tubules formation in collagen gel assays; iii) increased the expression of p-PAK1. CONCLUSION: PKCε negatively interferes with vessel progenitor differentiation via interaction with PAK-1.

Effect of Smad pathway activation on podocyte cell cycle regulation: an immunohistochemical evaluation.

BACKGROUND: Mature podocytes are in cell cycle arrest and their inability to proliferate successfully is a consequence of negative cell-cycle regulators' expression, such as p57. Phosphorylated smad2/smad3 (pSmad2/3) is an intracellular heteromeric mediator of transforming growth factor beta (TGF-ß) signals and, together with co-activators such as P300, regulates gene transcription, including cell cycle regulator proteins. METHODS: In order to investigate Smad pathway activation and podocyte cell cycle regulation in glomerular injury, we studied the glomerular immunohistochemical expression of p57, pSmad2/3 and P300 in samples from 67 patients with various types of glomerulonephritis (GN) and 10 normal kidney tissue specimens. RESULTS: pSmad2/3 and p300 expression were found significantly increased in all glomerular cell types in both proliferative and nonproliferative GN, while a significant reduction in p57-positive podocytes was observed when compared to controls. Staining for p57 was found to inversely correlate to pSmad2/3 suggesting that glomerular Smad pathway activation is related to down-regulation of p57 expression in proliferative glomerulonephritis. To our knowledge, this is the first study that indicates a relation between the TGF-beta/Smad signalling pathway and the cell cycle regulatory protein p57 in human GN. CONCLUSION: The increased pSmad2/3 staining together with the reduced p57 expression found in biopsy specimens with intense interstitial inflammation, indicate a possible relation between interstitial inflammation, glomerular Smad pathway activation and podocyte cell-cycle deregulation.

Gremlin activates the Smad pathway linked to epithelial mesenchymal transdifferentiation in cultured tubular epithelial cells.

Gremlin is a developmental gene upregulated in human chronic kidney disease and in renal cells in response to transforming growth factor-ß (TGF-ß). Epithelial mesenchymal transition (EMT) is one process involved in renal fibrosis. In tubular epithelial cells we have recently described that Gremlin induces EMT and acts as a downstream TGF-ß mediator. Our aim was to investigate whether Gremlin participates in EMT by the regulation of the Smad pathway. Stimulation of human tubular epithelial cells (HK2) with Gremlin caused an early activation of the Smad signaling pathway (Smad 2/3 phosphorylation, nuclear translocation, and Smad-dependent gene transcription). The blockade of TGF-ß, by a neutralizing antibody against active TGF-ß, did not modify Gremlin-induced early Smad activation. These data show that Gremlin directly, by a TGF-ß independent process, activates the Smad pathway. In tubular epithelial cells long-term incubation with Gremlin increased TGF-ß production and caused a sustained Smad activation and a phenotype conversion into myofibroblasts-like cells. Smad 7 overexpression, which blocks Smad 2/3 activation, diminished EMT changes observed in Gremlin-transfected tubuloepithelial cells. TGF-ß neutralization also diminished Gremlin-induced EMT changes. In conclusion, we propose that Gremlin could participate in renal fibrosis by inducing EMT in tubular epithelial cells through activation of Smad pathway and induction of TGF-ß.

Aberrant methylation and decreased expression of the TGF-ß/Smad target gene FBXO32 in esophageal squamous cell carcinoma.

BACKGROUND: F-box protein 32 (FBXO32) (also known as atrogin-1), a member of the F-box protein family, has recently been identified as a transforming growth factor beta (TGF-ß)/Smad target gene involved in regulating cell survival, and it may be transcriptionally silenced by epigenetic mechanisms in some kinds of carcinomas, yet its role in esophageal squamous cell carcinoma (ESCC) has not been defined. METHODS: The role of FBXO32 in ESCC and the correlation of FBXO32 methylation with a series of pathologic parameters were studied in a large cohort of patients with ESCC. RESULTS: Decreased messenger RNA (mRNA) expression and protein expression of FBXO32 were observed in esophageal cancer cell lines, and the silencing of FBXO32 could be reversed by treatment with 5-aza-2'-deoxycytidine or trichostatin A in the TE13 cell line. In addition, aberrant methylation of FBXO32 and histone deacetylation was capable of suppressing FBXO32 mRNA and protein expression in TE13 cells. Decreased mRNA and protein expression of FBXO32 was observed in ESCC tumor tissues and was associated with FBXO32 promoter methylation status. A positive correlation between FBXO32 and phosphorylated SMAD family members 2 and 3 expression and Smad4 protein expression also was observed in clinical specimens. FBXO32 methylation status and protein expression were independently associated with survival in patients with ESCC. CONCLUSIONS: FBXO32 may be a functional tumor suppressor. Its inactivation through promoter methylation could play an important role in ESCC carcinogenesis, and reactivation of the FBXO32 gene may have therapeutic potential and might be used as a prognostic marker for patients with ESCC.

The effect of ultraviolet radiation on the transforming growth factor beta 1/Smads pathway and p53 in actinic keratosis and normal skin.

Ultraviolet (UV) radiation is considered to be essential for the progression of actinic keratosis (AK) to squamous cell carcinoma (SCC); however, the mechanisms have not been fully elucidated. To understand this process, the effects of UV radiation on the transforming growth factor beta 1 (TGFß1)/Smads pathway and p53 in normal skin and AK were studied. Normal human skin and AK tissues were cultured and divided into the following four groups according to the UV radiation dose: 0 (control group), 5, 10, and 20 J/cm2. The tissues were radiated for four consecutive days; 24 h after radiation, the tissues were collected for investigation. Compared with the control group, greater proliferative inhibition and apoptosis were induced by UV radiation in normal skin than AK. The expression of TGFß1, Smad7, and p53 was increased in AK and normal skin, while the level of TßRII was decreased. Smad2 was reduced in AK only. The expressions of TßRI, Smad3, and Smad4 were not significantly changed. The results demonstrated that although p53 was induced, suppression of the TGFß1/Smads pathway by UV radiation might contribute to the progression of AK to SCC.

VEGF induces TGF-ß1 expression and myofibroblast transformation after glaucoma surgery.

Subconjunctival fibrosis at the surgical site determines the outcome of glaucoma surgery. Myofibroblast transformation has a significant role in fibrosis, and vascular endothelial growth factor (VEGF) is reported to trigger myofibroblast transformation by inducing transforming growth factor (TGF)-ß1. In the present study, we used IHC, Western blot analysis, enzyme-linked immunosorbent assay, and electron microscopy to determine the contribution of VEGF to myofibroblast transformation in subconjunctival fibrosis after glaucoma surgery. A rabbit trabeculectomy model was generated, and VEGF stimulation or VEGF inhibition was performed during surgery. VEGF stimulation induced TGF-ß1 expression in a dose-dependent manner. Down-regulation of epithelial markers (E-cadherin and ß-catenin) and up-regulation of mesenchymal marker (α-smooth muscle actin) were observed in the subconjunctival layers after trabeculectomy with VEGF stimulation. Up-regulations of Smad and Snail, which play a central role in myofibroblast transformation, were observed in the conjunctival and subconjunctival layers at the site of trabeculectomy. Electron microscopy revealed changes of the conjunctival epithelial cells, especially the presence of myofilaments and increased rough endoplasmic reticulum in the cytoplasm. Myofibroblast transformation was activated by VEGF stimulation and decreased by VEGF inhibition. These findings suggest that VEGF potentially affected the TGF-ß1/Smad/Snail pathway, thereby triggering myofibroblast transformation. Therapeutic approaches modulating VEGF may control myofibroblast transformation and reduce subconjunctival fibrosis after glaucoma surgery.