Atractylodinol prevents pulmonary fibrosis through inhibiting TGF-β receptor 1 recycling by stabilizing vimentin

Pirfenidone and nintedanib are only anti-pulmonary fibrosis (PF) drugs approved by the FDA. However, they are not target specific, and unable to modify the disease status. Therefore, it is still desirable to discover more effective agents against PF. Vimentin (VIM) plays key roles in tissue regeneration and wound healing, but its molecular mechanism remains unknown. In this work, we demonstrated that atractylodinol (ATD) significantly inhibits TGF-β1-induced epithelial-mesenchymal transition and fibroblast-to-myofibroblast transition in vitro. ATD also reduces bleomycin-induced lung injury and fibrosis in mice models. Mechanistically, ATD inhibited TGF-β receptor I recycling by binding to VIM (KD = 454 nM) and inducing the formation of filamentous aggregates. In conclusion, we proved that ATD (derived from Atractylodes lancea) modified PF by targeting VIM and inhibiting the TGF-β/Smad signaling pathway. Therefore, VIM is a druggable target and ATD is a proper drug candidate against PF. We prove a novel VIM function that TGF-β receptor I recycling. These findings paved the way to develop new targeted therapeutics against PF.

TGF-β Type II Receptor Punt Suppresses Antimicrobial Peptide Expression and Influences Development in Tribolium castaneum

The transforming growth factor-β (TGF-β) superfamily in insects regulated various physiological events, including immune response, growth and development, and metamorphosis. This complex network of signaling pathways involves conserved cell-surface receptors and signaling co-receptors that allow for precisely coordinated cellular events. However, the roles of TGF-β receptors, particularly the type II receptor Punt, in mediating the innate immunity in insects remains unclear. In this study, we used the red flour beetle, Tribolium castaneum, as a model species to investigate the role of TGF-β type II receptor Punt in mediating antimicrobial peptide (AMP) expression. Developmental and tissue-specific transcript profiles revealed Punt was constitutively expressed throughout development, with the highest transcript level in 1-day female pupae and the lowest transcript level in 18-day larvae. Tissue specific expression profiles showed the highest transcript level of Punt was observed in the Malpighian tubule and ovary in 18-day larvae and 1-day female adults, respectively, suggesting Punt might have distinct functions in larvae and adults. Further results indicated that Punt RNAi in the 18-day larvae led to increased transcript level of AMP genes through transcription factor Relish, leading to inhibition of Escherichia coli proliferation. Knockdown of Punt in larvae also led to splitting of adult elytra and abnormal compound eyes. Furthermore, knockdown of Punt during the female pupal stage resulted in increased transcript levels of AMP genes, as well as abnormal ovary, reduced fecundity, and failure of eggs to hatch. This study deepens our understanding of the biological significance of Punt in insect TGF-β signaling and lays the groundwork for further research of its role in insect immune response, development, and reproduction.

Therapeutic Effect of Polymeric Nanomicelles Formulation of LY2157299-Galunisertib on CCl4-Induced Liver Fibrosis in Rats

Hepatic fibrosis (HF) is a major cause of liver-related disorders and together with cancer-associated fibroblasts can favor liver cancer development by modulating the tumor microenvironment. Advanced HF, characterized by an excess of extracellular matrix (ECM), is mediated by TGF- β1, that activates hepatic stellate cells (HSCs) and fibroblasts. A TGF-β1 receptor inhibitor, LY2157299 or Galunisertib (GLY), has shown promising results against chronic liver progression in animal models, and we show that it can be further improved by enhancing GLYs bioavailability through encapsulation in polymeric polygalacturonic-polyacrylic acid nanomicelles (GLY-NMs). GLY-NMs reduced HF in an in vivo rat model of liver fibrosis induced by intraperitoneal injection of CCl₄ as shown by the morphological, biochemical, and molecular biology parameters of normal and fibrotic livers. Moreover, GLY-NM was able to induce recovery from HF better than free GLY. Indeed, the encapsulated drug reduces collagen deposition, hepatic stellate cells (HSCs) activation, prevents fatty degeneration and restores the correct lobular architecture of the liver as well as normalizes the serum parameters and expression of the genes involved in the onset of HF. In summary, GLY-NM improved the pharmacological activity of the free TGF- β1 inhibitor in the in vivo HF treatment and thus is a candidate as a novel therapeutic strategy.

The TGF-β Receptor Gene Saxophone Influences Larval-Pupal-Adult Development in Tribolium castaneum

The transforming growth factor-β (TGF-β) superfamily encodes a large group of proteins, including TGF-β isoforms, bone morphogenetic proteins and activins that act through conserved cell-surface receptors and signaling co-receptors. TGF-β signaling in insects controls physiological events, including growth, development, diapause, caste determination and metamorphosis. In this study, we used the red flour beetle, Tribolium castaneum, as a model species to investigate the role of the type I TGF-β receptor, saxophone (Sax), in mediating development. Developmental and tissue-specific expression profiles indicated Sax is constitutively expressed during development with lower expression in 19- and 20-day (6th instar) larvae. RNAi knockdown of Sax in 19-day larvae prolonged developmental duration from larvae to pupae and significantly decreased pupation and adult eclosion in a dose-dependent manner. At 50 ng dsSax/larva, Sax knockdown led to an 84.4% pupation rate and 46.3% adult emergence rate. At 100 ng and 200 ng dsSax/larva, pupation was down to 75.6% and 50%, respectively, with 0% adult emergence following treatments with both doses. These phenotypes were similar to those following knockdowns of 20-hydroxyecdysone (20E) receptor genes, ecdysone receptor (EcR) or ultraspiracle protein (USP). Expression of 20E biosynthesis genes disembodied and spookier, 20E receptor genes EcR and USP, and 20E downstream genes BrC and E75, were suppressed after the Sax knockdown. Topical application of 20E on larvae treated with dsSax partially rescued the dsSax-driven defects. We can infer that the TGF-β receptor gene Sax influences larval-pupal-adult development via 20E signaling in T. castaneum.

Connective Tissue Disorders and Cardiovascular Complications: The Indomitable Role of Transforming Growth Factor-β Signaling

Marfan Syndrome (MFS) and Loeys-Dietz Syndrome (LDS) represent heritable connective tissue disorders that segregate with a similar pattern of cardiovascular defects (thoracic aortic aneurysm, mitral valve prolapse/regurgitation, and aortic dilatation with regurgitation). This pattern of cardiovascular defects appears to be expressed along a spectrum of severity in many heritable connective tissue disorders and raises suspicion of a relationship between the normal development of connective tissues and the cardiovascular system. With overwhelming evidence of the involvement of aberrant Transforming Growth Factor-beta (TGF-β) signaling in MFS and LDS, this signaling pathway may represent the common link in the relationship between connective tissue disorders and their associated cardiovascular complications. To further explore this hypothetical link, this chapter will review the TGF-β signaling pathway, the heritable connective tissue syndromes related to aberrant TGF-β signaling, and will discuss the pathogenic contribution of TGF-β to these syndromes with a primary focus on the cardiovascular system.

Pathophysiology and Pathogenesis of Marfan Syndrome

Marfan syndrome (MFS) is a systemic connective tissue disorder that is inherited in an autosomal dominant pattern with variable penetrance. While clinically this disease manifests in many different ways, the most life-threatening manifestations are related to cardiovascular complications including mitral valve prolapse, aortic insufficiency, dilatation of the aortic root, and aortic dissection. In the past 30 years, research efforts have not only identified the genetic locus responsible but have begun to elucidate the molecular pathogenesis underlying this disorder, allowing for the development of seemingly rational therapeutic strategies for treating affected individuals. In spite of these advancements, the cardiovascular complications still remain as the most life-threatening clinical manifestations. The present chapter will focus on the pathophysiology and clinical treatment of Marfan syndrome, providing an updated overview of the recent advancements in molecular genetics research and clinical trials, with an emphasis on how this information can focus future efforts toward finding betters ways to detect, diagnose, and treat this devastating condition.

Integrin β1 Promotes Pancreatic Tumor Growth by Upregulating Kindlin-2 and TGF-β Receptor-2

The tumor microenvironment plays a critical role in defining the growth and malignancy of solid tumors. Extracellular matrix (ECM) proteins such as collagen, vitronectin, and fibronectin are major components of the tumor microenvironment. Tumor growth-promoting reciprocal interaction between ECM and cytoplasmic proteins is regulated by the cell surface receptors called integrins. This study investigated the mechanism by which integrin β1 promotes pancreatic tumor growth. In MIA PaCa-2 pancreatic cancer cell line, the loss of integrin β1 protein reduced the ability of cells to proliferate in a 3D matrix and compromised the ability to form a focal adhesion complex. Decreased expression of integrin α5 was observed in KO cells, which resulted in impaired cell spreading and adhesion on vitronectin and fibronectin. Reduced expression of the integrin-associated protein, kindlin-2 was also recorded. The downregulation of kindlin-2 decreased the phosphorylation of Smad2/3 by reducing the expression of TGF-β receptor 2. These results unravel a new mechanism of integrin β1 in tumor growth by modifying the expression of kindlin-2 and TGF-β receptor 2 signaling.

4D-QSAR models applied to the study of TGF- β1 receptor inhibitors

BACKGROUND

The quantitative structure-activity relationship is an analysis method that can be applied for designing new molecules. In 1997, Hopfinger and coworkers developed the 4D-QSAR methodology aiming to eliminate the question of which conformation to use in a QSAR study. In this work, the 4D-QSAR methodology was used to quantitatively determine the influence of structural descriptors on the activity of aryl pyrimidine derivatives as inhibitors of the TGF-β1 receptor. The members of the TGF-β subfamily are interesting molecular targets, since they play an important function in the growth and development of cell cellular including proliferation, apoptosis, differentiation, epithelial-mesenchymal transition (EMT), and migration. In late stages, TGF-β exerts tumor-promoting effects, increasing tumor invasiveness, and metastasis. Therefore, TGF-β is an attractive target for cancer therapy.

OBJECTIVE

The major goal of the current research is to develop 4D-QSAR models aiming to propose new structures of aryl pyrimidine derivatives.

MATERIALS AND METHODS

Molecular dynamics simulation was carried out to generate the conformational ensemble profile of a data set with aryl pyrimidine derivatives. The conformations were overlaid into a three-dimensional cubic box, according to the three-ordered atom alignment. The occupation of the grid cells by the interaction of pharmacophore elements provides the grid cell occupancy descriptors (GCOD), the dependent variables used to build the 4D-QSAR models. The best models were validated (internal and external validation) using several statistical parameters. Docking molecular studies were performed to better understand the binding mode of pyrimidine derivatives inside the TGF-β active site.

RESULTS

The 4D-QSAR model presented seven descriptors and acceptable statistical parameters (R2 = 0.89, q2 = 0.68, R2pred = 0.65, r2m = 0.55, R2P = 0.68 and R2rand = 0.21) besides pharmacophores groups important for the activity of these compounds. The molecular docking studies helped to understand the pharmacophoric groups and proposed substituents that increase the potency of aryl pyrimidine derivatives.

CONCLUSION

The best QSAR model showed adequate statistical parameters that ensure their fitness, robustness, and predictivity. Structural modifications were assessed, and five new structures were proposed as candidates for a drug for cancer treatment.

FUT8 and Protein Core Fucosylation in Tumours: From Diagnosis to Treatment

Glycosylation changes are key molecular events in tumorigenesis, progression and glycosyltransferases play a vital role in the this process. FUT8 belongs to the fucosyltransferase family and is the key enzyme involved in N-glycan core fucosylation. FUT8 and/or core fucosylated proteins are frequently upregulated in liver, lung, colorectal, pancreas, prostate,breast, oral cavity, oesophagus, and thyroid tumours, diffuse large B-cell lymphoma, ependymoma, medulloblastoma and glioblastoma multiforme and downregulated in gastric cancer. They can be used as markers of cancer diagnosis, occurrence, progression and prognosis. Core fucosylated EGFR, TGFBR, E-cadherin, PD1/PD-L1 and α3β1 integrin are potential targets for tumour therapy. In addition, IGg1 antibody defucosylation can improve antibody affinity, which is another aspect of FUT8 that could be applied to tumour therapy.

Enhanced Intestinal TGF-β/SMAD-Dependent Signaling in Simian Immunodeficiency Virus Infected Rhesus Macaques

Transforming growth factor-β signaling (TGF-β) maintains a balanced physiological function including cell growth, differentiation, and proliferation and regulation of immune system by modulating either SMAD2/3 and SMAD7 (SMAD-dependent) or SMAD-independent signaling pathways under normal conditions. Increased production of TGF-β promotes immunosuppression in Human Immunodeficiency Virus (HIV)/Simian Immunodeficiency Virus (SIV) infection. However, the cellular source and downstream events of increased TGF-β production that attributes to its pathological manifestations remain unknown. Here, we have shown increased production of TGF-β in a majority of intestinal CD3⁻CD20⁻CD68⁺ cells from acute and chronically SIV infected rhesus macaques, which negatively correlated with the frequency of jejunum CD4⁺ T cells. No significant changes in intestinal TGF-β receptor II expression were observed but increased production of the pSMAD2/3 protein and SMAD3 gene expression in jejunum tissues that were accompanied by a downregulation of SMAD7 protein and gene expression. Enhanced TGF-β production by intestinal CD3⁻CD20⁻CD68⁺ cells and increased TGF-β/SMAD-dependent signaling might be due to a disruption of a negative feedback loop mediated by SMAD7. This suggests that SIV infection impacts the SMAD-dependent signaling pathway of TGF-β and provides a potential framework for further study to understand the role of viral factor(s) in modulating TGF-β production and downregulating SMAD7 expression in SIV. Regulation of mucosal TGF-β expression by therapeutic TGF-β blockers may help to create effective antiviral mucosal immune responses.

Identification and functional analysis of transforming growth factor-β type III receptor (TβR3) from Scylla paramamosain: The first evidence of TβR3 involved in development and innate immunity in invertebrates

Transforming growth factor-β type III receptor (TβR3), as a co-receptor of TGF-β superfamily, plays critical roles in development and growth as well as some disease pathogeneses by presenting ligands to other receptors in vertebrates. However, the identification and functional characterization of TβR3 had not been reported yet in invertebrates. In the present study, TβR3 was first identified and characterized in mud crab Scylla paramamosain. The obtained cDNA length of SpTβR3 was 2, 424 bp with a 1, 854 bp open reading frame, which encoded a putative peptide of 617 amino acids containing a typical transmembrane region and a Zona pellucida (ZP) domain. Real-time PCR results showed that SpTβR3 was predominantly expressed at early embryonic development stage and early postmolt stage, suggesting its participation in development and growth. We report, for the first time in invertebrates, the challenge of both Vibro alginolyticus and Poly (I:C) could alter the expression patterns of SpTβR3. Notably, the expression levels of SpIKK, two NF-κB members (SpRelish and SpDorsal), and five antimicrobial peptide genes (SpCrustin and SpALF1-4) were significantly suppressed when SpTβR3 was interfered in vivo. Secondly, the overexpression of SpTβR3 in vitro could activate NF-κB signaling through the dual-luciferase reporter assays. Furthermore, the bacterial clearance assay after SpTβR3 was silenced in vivo highlighted the potential of SpTβR3 in activating the innate immune responses. These results implied the involvement of SpTβR3 in the innate immune responses by regulating the NF-κB pathway. This study first indicated that TβR3 was present in invertebrate, and it participated in not only the development and growth but also the innate immunity of S. paramamosain. It also provided new insights into the origin or evolution of TGF-β receptors in crustacean species and even in invertebrates.

Oridonin inhibits 4T1 tumor growth by suppressing Treg differentiation via TGF-β receptor

The Chinese herbal medicine oridonin has potent anti-inflammatory and antitumor activities. In addition, oridonin treatment effectively suppresses breast cancer growth. However, the underlying mechanisms are poorly defined. Here, we reported that oridonin decreased Treg differentiation in vitro and in vivo. Oridonin inhibition of Treg differentiation was dependent on decreasing TGF-β receptor expression. Oridonin attenuated Tregs' immunosuppressive ability; thus, oridonin did not inhibit CD8⁺ T cell proliferation very well in vitro. Oridonin greatly delayed the progression of 4T1 tumors in vivo. In addition, oridonin combined with anti-PD-1 activated a robust antitumor immune response and suppressed 4T1 tumor growth. Therefore, our results indicate that oridonin inhibits TNBC growth by modulating Treg differentiation, which provides new directions for the clinical treatment of TNBC.

Development of small molecule inhibitors targeting TGF-β ligand and receptor: Structures, mechanism, preclinical studies and clinical usage

Transforming growth factor-β (TGF-β) is a member of a superfamily of pleiotropic proteins that regulate multiple cellular processes such as growth, development and differentiation. Following binding to type I and II TGF-β serine/threonine kinase receptors, TGF-β activates downstream signaling cascades involving both SMAD-dependent and -independent pathways. Aberrant TGF-β signaling is associated with a variety of diseases, such as fibrosis, cardiovascular disease and cancer. Hence, the TGF-β signaling pathway is recognized as a potential drug target. Various organic molecules have been designed and developed as TGF-β signaling pathway inhibitors and they function by either down-regulating the expression of TGF-β or by inhibiting the kinase activities of the TGF-β receptors. In this review, we discuss the current status of research regarding organic molecules as TGF-β inhibitors, focusing on the biological functions and the binding poses of compounds that are in the market or in the clinical or pre-clinical phases of development.

Graphene Oxide Promotes Cancer Metastasis through Associating with Plasma Membrane To Promote TGF-β Signaling-Dependent Epithelial-Mesenchymal Transition

Nanomedicines are being developed to treat diverse diseases; however, inadvertent or unintended health effects have to be considered, especially for those targeting cancers. For cancers, occurrence of metastasis hints an advanced phase of cancer progression, and nanomedicines per se should be evaluated for their effects on existing metastatic tumors and triggering metastases. Graphene-based 2D nanomaterials, such as graphene oxide (GO), due to its unique characteristics, have been extensively studied for biomedical applications including cancer therapy. However, the potential effect of GO on metastasis has not been determined yet. Herein, we found that low-dose GO could induce significant morphological and structural changes of the cellular membrane within cancer cells, suggesting an epithelial-mesenchymal transition (EMT), with enhanced invasion/migration and the alterations of representative EMT indicators in GO-treated cells. These changes resulted in enhanced lung metastasis of cancer cells in various metastasis models. The mechanistic investigations unveiled that GO increased the protein levels of the TGF-β receptor, leading to a constitutively activated TGF-β-Smad2/3 signaling pathway that drives the EMT. Collectively, our findings enhance the understanding of the unintended side and detrimental effects of GO nanosheets in increasing the progression of metastatic tumors. Thus, the likelihood of pro-EMT effects upon low-dose GO exposure should be considered when developing GO nanomedicines.

Suppression of TGF-β and IL-10 receptors on self-differentiated dendritic cells by short-hairpin RNAs enhanced activation of effector T-cells against cholangiocarcinoma cells

Cholangiocarcinoma (CCA) is an aggressive tumor that is associated with high rates of recurrence and mortality. This is due, in part, to the fact that CCA cells and their microenvironment secrete immunosuppressive cytokines, transforming growth factor-β (TGF-β) and interleukin-10 (IL-10), that inhibit dendritic cell (DC) functions, which, in turn, results in the decreased anti-tumor activity of T-cells. We hypothesized that the TGF-β receptor and IL-10 blockade on dendritic cells would improve DC function, thereby allowing improved activation of T cells against CCA cells. To test our hypothesis, we generated self-differentiated DCs (SD-DCs) via transduction of human peripheral blood monocytes with lentivirus expressing IL-4 and GM-CSF. SD-DCs were transduced with a second lentivirus containing short-hairpin RNAs (shRNAs) to knock-down TGF-βRII and IL-10RA mRNAs. Immunoblot confirmed the reduced expression levels of TGF-β and IL-10 receptors in both SD-DCs that were transduced with a single and/or combination of lentiviruses containing shRNAs. SD-DCs were thereafter pulsed with tumor antigens extracted from CCA cell lines in an effort to activate DC function. MHC class II (HLA-DR) and co-stimulatory molecules (CD40 and CD86) on SD-DCs were upregulated to levels comparable to those on DCs generated by the conventional method. Suppression of TGF-β and IL-10 receptors on SD-DCs influenced the effector T-cells to produce IFN-γ, which enhanced their ability to kill CCA cells. The preparation of adoptive effector T-cells holds the potential of becoming a novel therapy for cellular immunotherapy in CCA.

RepSox, a small molecule inhibitor of the TGFβ receptor, induces brown adipogenesis and browning of white adipocytes

Unlike white adipose tissue (WAT), brown adipose tissue (BAT) is mainly responsible for energy expenditure via thermogenesis by uncoupling the respiratory chain. Promoting the differentiation of brown fat precursor cells and the browning of white fat have become a research hotspot for the treatment of obesity and associated metabolic diseases. Several secreted factors and a number of small molecules have been found to promote brown adipogenesis. Here we report that a single small-molecule compound, RepSox, is sufficient to induce adipogenesis from mouse embryonic fibroblasts (MEFs) in fibroblast culture medium. RepSox is an inhibitor of the transforming growth factor-beta receptor I (TGF-β-RI), other inhibitors of TGF-β pathway such as SB431542, LY2157299, A83-01, and Tranilast are also effective in inducing adipogenesis from MEFs. These adipocytes express brown adipocyte-specific transcription factors and thermogenesis genes, and contain a large number of mitochondria and have a high level of mitochondrial respiratory activity. More interestingly, RepSox has also been found to promote the differentiation of the brown fat precursor cells and induce browning of the white fat precursor cells. These findings suggest that inhibitors of TGF-β signaling pathway might be developed as new therapeutics for obesity and type 2 diabetes.

Conditional knockout of TGF-βRII /Smad2 signals protects against acute renal injury by alleviating cell necroptosis, apoptosis and inflammation

Rationale: TGF-β/Smad signaling is the central mediator for renal fibrosis, however, its functional role in acute kidney injury (AKI) is not fully understood. We previously showed Smad2 protects against renal fibrosis by limiting Smad3 signaling, but details on its role in acute phase are unclear. Recent evidence showed that TGF-β/Smad3 may be involved in the pathogenesis of AKI, so we hypothesized that Smad2 may play certain roles in AKI due to its potential effect on programmed cell death.

Methods: We established a cisplatin-induced AKI mouse model with TGF-β type II receptor or Smad2 specifically deleted from renal tubular epithelial cells (TECs). We also created stable in vitro models with either Smad2 knockdown or overexpression in human HK2 cells. Importantly, we evaluated whether Smad2 could serve as a therapeutic target in both cisplatin- and ischemic/reperfusion (I/R)-induced AKI mouse models by silencing Smad2 in vivo.

Results: Results show that disruption of TGF-β type II receptor suppressed Smad2/3 activation and attenuated renal injury in cisplatin nephropathy. Furthermore, we found that conditional knockout of downstream Smad2 in TECs protected against loss of renal function, and alleviated p53-mediated cell apoptosis, RIPK-mediated necroptosis and p65 NF-κB-driven renal inflammation in cisplatin nephropathy. This was further confirmed in cisplatin-treated Smad2 knockdown and overexpression HK2 cells. Additionally, lentivirus-mediated Smad2 knockdown protected against renal injury and inflammation while restoring renal function in established nephrotoxic and ischemic AKI models.

Conclusions: These findings show that unlike its protective role in renal fibrosis, Smad2 promoted AKI by inducing programmed cell death and inflammation. This may offer a novel therapeutic target for acute kidney injury.

TNAP limits TGF-β-dependent cardiac and skeletal muscle fibrosis by inactivating the SMAD2/3 transcription factors

Fibrosis is associated with almost all forms of chronic cardiac and skeletal muscle diseases. The accumulation of extracellular matrix impairs the contractility of muscle cells contributing to organ failure. Transforming growth factor β (TGF-β) plays a pivotal role in fibrosis, activating pro-fibrotic gene programmes via phosphorylation of SMAD2/3 transcription factors. However, the mechanisms that control de-phosphorylation of SMAD2 and SMAD3 (SMAD2/3) have remained poorly characterized. Here, we show that tissue non-specific alkaline phosphatase (TNAP, also known as ALPL) is highly upregulated in hypertrophic hearts and in dystrophic skeletal muscles, and that the abrogation of TGF-β signalling in TNAP-positive cells reduces vascular and interstitial fibrosis. We show that TNAP colocalizes and interacts with SMAD2. The TNAP inhibitor MLS-0038949 increases SMAD2/3 phosphorylation, while TNAP overexpression reduces SMAD2/3 phosphorylation and the expression of downstream fibrotic genes. Overall our data demonstrate that TNAP negatively regulates TGF-β signalling and likely represents a mechanism to limit fibrosis.

GDF15 induced apoptosis and cytotoxicity in A549 cells depends on TGFBR2 expression

GDF15 plays a paradoxical role during carcinogenesis; it inhibits tumour growth in the early stages and promotes tumour cell proliferation in the late stages of cancer. Besides, GDF15 can induce apoptosis in some cancer cells including A549 but not in some others. Moreover, as a potential receptor for GDF15, TGFBR2 is inactivated during carcinogenesis in many types of cancers, and it is not present in cells with no GDF15 induced apoptosis. Thus, we tested whether GDF15 overexpression and/or TGFBR2 silencing can affect the GDF15 induced apoptosis in A549 cells. The full and mature forms of GDF15 were cloned and overexpressed in A549 cells. The TGFBR2 was silenced using specific siRNA and confirmed by real-time PCR. Results indicated that overexpression of full and mature forms of GDF15 as well as TGFBR2 knocked down reduced A549 cell viability in 24 and 48 hours. Flow cytometric analysis of annexin V/PI indicated induction of apoptosis in A549 cells by overexpression of GDF15 or silencing TGFBR2. Interestingly, the silencing of TGFBR2 inhibited the GDF15 induced cytotoxicity and apoptosis in A549 cells. Overexpression of GDF15 activated caspase-9 and caspase-3 and inhibited ERK1/2 and p38 phosphorylation in A549 cells. TGFBR2 knocked down inhibited GDF15 effects on caspases, ERK1/2, and p38MAPK activation. Our results indicated that the effect of GDF15 on apoptosis and activation of MAPK in A549 cells depends on TGFBR2 expression. These findings may point to mechanisms in which GDF15 exerts dual effect during carcinogenesis with regard to TGFBR2 expression. SIGNIFICANCE OF THE STUDY: GDF15 plays a tumour suppressor or promotor roles during carcinogenesis. The expression of GDF15 induced cytotoxicity, apoptosis, and inhibition of MAPK in A549 cells. All these effects were blocked by silencing TGFBR2 expression. These findings may point to mechanisms in which GDF15 exerts dual effect during carcinogenesis with regard to TGFBR2 expression.

POH1 contributes to hyperactivation of TGF-β signaling and facilitates hepatocellular carcinoma metastasis through deubiquitinating TGF-β receptors and caveolin-1

Background

Hyper-activation of TGF-β signaling is critically involved in progression of hepatocellular carcinoma (HCC). However, the events that contribute to the dysregulation of TGF-β pathway in HCC, especially at the post-translational level, are not well understood.

Methods

Associations of deubiquitinase POH1 with TGF-β signaling activity and the outcomes of HCC patients were examined by data mining of online HCC datasets, immunohistochemistry analyses using human HCC specimens, spearman correlation and survival analyses. The effects of POH1 on the ubiquitination and stability of the TGF-β receptors (TGFBR1 and TGFBR2) and the activation of downstream effectors were tested by western blotting. Primary mouse liver tissues from polyinosinic:polycytidylic acid (poly I:C)- treated Mx-Cre+, poh1^f/f mice and control mice were used to detect the TGF-β receptors. The metastatic-related capabilities of HCC cells were studied in vitro and in mice.

Findings

Here we show that POH1 is a critical regulator of TGF-β signaling and promotes tumor metastasis. Integrative analyses of HCC subgroups classified with unsupervised transcriptome clustering of the TGF-β response, metastatic potential and outcomes, reveal that POH1 expression positively correlates with activities of TGF-β signaling in tumors and with malignant disease progression. Functionally, POH1 intensifies TGF-β signaling delivery and, as a consequence, promotes HCC cell metastatic properties both in vitro and in vivo. The expression of the TGF-β receptors was severely downregulated in POH1-deficient mouse hepatocytes. Mechanistically, POH1 deubiquitinates the TGF-β receptors and CAV1, therefore negatively regulates lysosome pathway-mediated turnover of TGF-β receptors.

Conclusion

Our study highlights the pathological significance of aberrantly expressed POH1 in TGF-β signaling hyperactivation and aggressive progression in HCC.

Identification and functional analysis of transforming growth factor-β type I receptor (TβR1) from Scylla paramamosain: The first evidence of TβR1 involved in development and innate immunity in crustaceans

The transforming growth factor-β (TGF-β) receptor-mediated TGF-β signaling cascade plays important roles in diverse cellular processes, including cell proliferation, differentiation, growth, apoptosis and inflammation in vertebrates. In the present study, the type I TGF-β receptor (TβR1) was firstly identified and characterized in mud crab Scylla paramamosain. The full-length cDNA of SpTβR1 was 1, 986 bp with a 1, 608 bp open reading frame, which encoded a putative protein of 535 amino acids including a typical transmembrane region, a conserved glycine-serine (GS) motif and a S_TKc domain (Serine/Threonine protein kinases, catalytic domain). Real-time PCR analysis showed that SpTβR1 was predominantly expressed at early embryonic development stage and was highly expressed at postmolt stages during molt cycle, suggesting its participation in development and growth. Moreover, the expression levels of SpTβR1 in hepatopancreas and hemocytes were positively induced after the challenges of Vibro alginolyticus and Poly (I:C), indicating the involvement of SpTβR1 in responding to both bacterial and viral infections. The in vivo RNA interference assays demonstrated that the expression levels of two NF-κB members (SpRelish and SpDorsal) and six antimicrobial peptide (AMP) genes (SpCrustin and SpALF2-6) were significantly suppressed when the SpTβR1 was silenced. Additionally, the expression levels of SpTβR1, SpRelish, SpDorsal and AMPs were consistently down-regulated or up-regulated when the primary cultured hemocytes were treated with TβR1 antagonist or agonist for 24 h. These results indicated that TβR1 not only contributed to the crabs' development and growth but also played vital role in the innate immunity of S. paramamosain, and it also provided new insights into the origin or evolution of TGF-β receptors in crustacean species and even in invertebrates.

Computational investigation of TGF-β receptor inhibitors for treatment of idiopathic pulmonary fibrosis: Field-based QSAR model and molecular dynamics simulation

The discovery of drugs relevant to transforming growth factor β (TGF-β) receptor inhibitors have been considered as a considerable challenge during therapy idiopathic pulmonary fibrosis diseases. For the first time, herein we illustrate a field-based quantitative structure-activity relationship (QSAR) model and molecular dynamics (MD) simulations for novel 7-substituted-pyrazolo [4, 3-b] pyridine derivatives with biological activity for the TGF-β receptor, with an attempt of elucidating the 3D structural features that are essential for the activity. Results demonstrate that the field-based model (Q² = 0.548, R²_training = 0.840, R²_test = 0.750) are acceptable with good predictive capabilities. In addition, MD studies were also carried out on the training set with the aim of exploring their binding modes in the active pocket of TGF-β receptor, resulting in some of the crucial structural fragments which are responsible for inhibitory activity. Therefore, we summarized the following features required for TGF-β receptor inhibition: electronegative in region1, bulky groups in region2 and smaller groups in region3. Based on the model and related information, we hope the above information provides an important insight for understanding the interactions of the inhibitors and TGF-β receptor, which may be useful in discovering novel potent inhibitors.

FUT8 promotes breast cancer cell invasiveness by remodeling TGF-β receptor core fucosylation

BACKGROUND

Core fucosylation (addition of fucose in α-1,6-linkage to core N-acetylglucosamine of N-glycans) catalyzed by fucosyltransferase 8 (FUT8) is critical for signaling receptors involved in many physiological and pathological processes such as cell growth, adhesion, and tumor metastasis. Transforming growth factor-β (TGF-β)-induced epithelial-mesenchymal transition (EMT) regulates the invasion and metastasis of breast tumors. However, whether receptor core fucosylation affects TGF-β signaling during breast cancer progression remains largely unknown.

METHOD

In this study, gene expression profiling and western blot were used to validate the EMT-associated expression of FUT8. Lentivirus-mediated gain-of-function study, short hairpin RNA (shRNA) or CRISPR/Cas9-mediated loss-of-function studies and pharmacological inhibition of FUT8 were used to elucidate the molecular function of FUT8 during TGF-β-induced EMT in breast carcinoma cells. In addition, lectin blot, luciferase assay, and in vitro ligand binding assay were employed to demonstrate the involvement of FUT8 in the TGF-β1 signaling pathway. The role of FUT8 in breast cancer migration, invasion, and metastasis was confirmed using an in vitro transwell assay and mammary fat pad xenograft in vivo tumor model.

RESULTS

Gene expression profiling analysis revealed that FUT8 is upregulated in TGF-β-induced EMT; the process was associated with the migratory and invasive abilities of several breast carcinoma cell lines. Gain-of-function and loss-of-function studies demonstrated that FUT8 overexpression stimulated the EMT process, whereas FUT8 knockdown suppressed the invasiveness of highly aggressive breast carcinoma cells. Furthermore, TGF-β receptor complexes might be core fucosylated by FUT8 to facilitate TGF-β binding and enhance downstream signaling. Importantly, FUT8 inhibition suppressed the invasive ability of highly metastatic breast cancer cells and impaired their lung metastasis.

CONCLUSIONS

Our results reveal a positive feedback mechanism of FUT8-mediated receptor core fucosylation that promotes TGF-β signaling and EMT, thus stimulating breast cancer cell invasion and metastasis.

N-glycans of growth factor receptors: their role in receptor function and disease implications

Numerous signal-transduction-related molecules are secreted proteins or membrane proteins, and the mechanism by which these molecules are regulated by glycan chains is a very important issue for developing an understanding of the cellular events that transpire. This review covers the functional regulation of epidermal growth factor receptor (EGFR), ErbB3 and the transforming growth factor β (TGF-β) receptor by N-glycans. This review shows that the N-glycans play important roles in regulating protein conformation and interactions with carbohydrate recognition molecules. These results point to the possibility of a novel strategy for controlling cell signalling and developing novel glycan-based therapeutics.

The prognostic importance of TGF-β, TGF-β receptor, and fascin in childhood solid tumors

Fascin plays a role in tumor metastasis under the influence of TGF-β, each potentiating the effect of the other. We retrospectively investigated whether there was a prognostic relationship between TGF-β and fascin, and disease stage, local recurrence, metastasis tendency, and response to treatment. Twelve neuroblastomas, 17 osteosarcomas, 14 Ewing's sarcomas, 15 rhabdomyosarcoma cases, and 8 rare solid tumors were included. Serum TGF-β levels were high at the time of diagnosis in all groups (p = .015) and decreased significantly during remission (p = .008). Serum TGF-β values in the relapse period rarely reached high levels at the time of diagnosis and even stayed under the control group values (p = .017). When TGF-β receptor expression in tumor tissues was evaluated, the association of TGF-β receptor positivity with metastatic disease and advanced stage was striking. We found that 88% of rhabdomyosarcoma cases with alveolar histopathology expressed the TGF-β receptor, and the association between TGF-β receptor positivity and alveolar histopathology seemed to be a negative prognostic marker. When fascin levels were evaluated in childhood solid tumor tissue, the risk of relapse increased when the fascin total score at diagnosis was >4. This is one of the few studies including prognostic markers such as serum TGF-β, tissue TGF-β, TGF-β receptor, and fascin in pediatric solid tumors. Considering the poor prognosis of advanced stage pediatric solid tumors and the need for biomarkers to predict which patient might need more intensive therapy or warrant closer follow-up afterward, we think that TGF-β, TGF-β receptor, and fascin expression have an important prognostic role.

Phase I study of PF-03446962, a fully human monoclonal antibody against activin receptor-like kinase-1, in patients with hepatocellular carcinoma

BACKGROUND

This expansion cohort of a multicenter, dose-escalation, phase I study (NCT00557856) evaluated safety, tolerability, antitumor activity, pharmacokinetics, and pharmacodynamic effects of the anti-activin receptor-like kinase-1 (ALK-1) monoclonal antibody PF-03446962 in advanced hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

Patients with HCC and disease progression after prior antiangiogenic therapy or intolerance to treatment received PF-03446962 7 mg/kg intravenously biweekly, as recommended in the dose-escalation part of the study.

RESULTS

Twenty-four patients received PF-03446962. The most frequent treatment-related adverse events (AEs) were thrombocytopenia (33.3%), asthenia (29.2), and chills (16.7%). Two patients experienced treatment-related telangiectasia, suggesting an in vivo knockout of ALK-1 function through ALK-1 pathway inhibition. Overall, treatment-related grade 3-4 AEs were reported in eight patients (33.3%). Treatment-related grade 3-4 thrombocytopenia was noted in four patients. No complete or partial responses were reported. Twelve (50%) patients achieved stable disease, which lasted ≥12 weeks in seven (29.2%) patients. The median time to progression was 3 months. Biomarker analyses showed higher mean tumor expression of c-tumor mesenchymal-epithelial transition factor and higher mean serum levels of bone morphogenetic protein-9 in patients with disease control (DC) for ≥12 weeks versus patients with disease progression. Conversely, lower mean serum transforming growth factor-β and vascular endothelial growth factor receptor-3 levels were detected in patients with DC versus patients with progression.

CONCLUSIONS

The observed safety, tolerability, pharmacokinetic profile, and clinical activity support further evaluation of PF-03446962 in patients with HCC and other solid malignancies, as single agent or in combination with other antiangiogenic, chemotherapeutic, or immunotherapeutic agents.

TRIAL REGISTRATION NUMBER

NCT00557856.

Disease-associated glycans on cell surface proteins

Most of membrane molecules including cell surface receptors and secreted proteins including ligands are glycoproteins and glycolipids. Therefore, identifying the functional significance of glycans is crucial for developing an understanding of cell signaling and subsequent physiological and pathological cellular events. In particular, the function of N-glycans associated with cell surface receptors has been extensively studied since they are directly involved in controlling cellular functions. In this review, we focus on the roles of glycosyltransferases that are involved in the modification of N-glycans and their target proteins such as epidermal growth factor receptor (EGFR), ErbB3, transforming growth factor β (TGF-β) receptor, T-cell receptors (TCR), β-site APP cleaving enzyme (BACE1), glucose transporter 2 (GLUT2), E-cadherin, and α5β1 integrin in relation to diseases and epithelial-mesenchymal transition (EMT) process. Above of those proteins are subjected to being modified by several glycosyltransferases such as N-acetylglucosaminyltransferase III (GnT-III), N-acetylglucosaminyltransferase IV (GnT-IV), N-acetylglucosaminyltransferase V (GnT-V), α2,6 sialyltransferase 1 (ST6GAL1), and α1,6 fucosyltransferase (Fut8), which are typical N-glycan branching enzymes and play pivotal roles in regulating the function of cell surface receptors in pathological cell signaling.

Endoglin overexpression mediates gastric cancer peritoneal dissemination by inducing mesothelial cell senescence

Peritoneal dissemination (PD), which is highly frequent in gastric cancer (GC) patients, is the main cause of death in advanced GC. Senescence of human peritoneal mesothelial cells (HPMC) may contribute to GC peritoneal dissemination (GCPD). In this study of 126 patients, we investigated the association between Endoglin expression in GC peritoneum and the clinicopathological features. The prognosis of patients was evaluated according to Endoglin and ID1 expression. In vitro, GC cell (GCC)-HPMC coculture was established. Endoglin and ID1 expression was evaluated by Western blot. Cell cycle and HPMC senescence were analyzed after harvesting HPMC from the coculture. GCC adhesion and invasion to HPMC were also assayed. Our results showed that positive staining of Endoglin (38%) was associated with a higher TNM stage and higher incidence of GCPD (both P < .05). Kaplan-Meier analysis showed that the patients who were Endoglin positive had a shorter survival time compared with Endoglin-negative patients (P = .02). Using the HPMC and GCC adherence and invasion assay, we demonstrated that transforming growth factor beta 1 (TGF-β)1-induced HPMC senescence was attenuated by silencing the Endoglin expression, which also prevented GCC attachment and invasion. Our study indicated a positive correlation between Endoglin overexpression and GCPD. Up-regulated Endoglin expression induced HPMC senescence via TGF-β1 pathway. The findings suggest that Endoglin-induced HPMC senescence may contribute to peritoneal dissemination of GCCs.

Posttranslational Modifications of TGF-β Receptors

TGF-β is a prototype of the TGF-β cytokine superfamily and exerts multiple regulatory effects on cell activities. It signals through two types of membrane-bound serine/threonine kinase receptors. Upon TGF-β binding, the type II receptor TβRII recruits the type I receptor TβRI and form a functional heterocomplex. TβRII trans-phosphorylates the GS region of TβRI, thus triggering its kinase activity. Activated TβRI proceeds to activate downstream Smad2/3. Signal intensity and duration through the availability, activity and destiny of TGF-β receptors are finely controlled by multiple posttranslational modifications such as phosphorylation, ubiquitination, and neddylation. This chapter introduces methods for examination of these modifications of TGF-β receptors.

Galangin suppresses HepG2 cell proliferation by activating the TGF-β receptor/Smad pathway

Galangin can suppress hepatocellular carcinoma (HCC) cell proliferation. In this study, we demonstrated that galangin induced autophagy by activating the transforming growth factor (TGF)-β receptor/Smad pathway and increased TGF-β receptor I (RI), TGF-βRII, Smad1, Smad2, Smad3 and Smad4 levels but decreased Smad6 and Smad7 levels. Autophagy induced by galangin appears to depend on the TGF-β receptor/Smad signalling pathway because the down-regulation of Smad4 by siRNA or inhibition of TGF-β receptor activation by LY2109761 blocked galangin-induced autophagy. The down-regulation of Beclin1, autophagy-related gene (ATG) 16L, ATG12 and ATG3 restored HepG2 cell proliferation and prevented galangin-induced apoptosis. Our findings indicate a novel mechanism for galangin-induced autophagy via activation of the TGF-β receptor/Smad pathway. The induction of autophagy thus reflects the anti-proliferation effect of galangin on HCC cells.

Functional role of TGF-β receptors during palatal fusion in vitro

OBJECTIVE

Reported expression patterns for TGF-β receptors (TβR-I, -II, and -III) during palatogenesis suggest that they play essential roles in the mechanisms leading to palatal fusion. The purpose of this study was to compare the functions of the three TβRs during palatal fusion.

METHODS

Using organ culture of mouse palatal shelves, expression levels of TβR-I, -II, and -III were suppressed by transfecting the siRNAs siTβR-I, -II, and -III, respectively. Phosphorylation of SMAD2 was examined as an indicator of downstream signalling via each TβR. Linkage between TGF-β signalling and critical events in palatal fusion led to the use of, MMP-13 expression as an outcome measure for the function of the TGF-β receptors.

RESULTS

The siRNA treatment decreased the expression level of each receptor by more than 85%. When treated with either siTβR-I or -II, palatal shelves at E13+72 h were not fused, with complete clefting in the anterior and posterior regions. The middle palatal region following treatment with either siTβR-I or -II had fusion from one-half or one-third of the palatal region. Treatment with siTβR-III resulted in a persistent midline seam of medial edge epithelium (MEE) in the anterior region with islands of persistent MEE in the middle and posterior regions of the midline. Treatment with all three siTβRs altered the pattern of SMAD2 phosphorylation. Palatal shelf cultures treated with siTβR-I or -II, but not -III, showed altered MMP-13 expression levels.

CONCLUSION

The ability to identify and recover MEE and palatal mesenchymal cells during palatal fusion will aid in the evaluation of the different mechanistic events regulated by each TβR during palatogenesis.

Targeting the TGF-β receptor with kinase inhibitors for scleroderma therapy

Scleroderma (systemic sclerosis) is a connective tissue disease that affects various organ systems; the treatment of scleroderma is still difficult and remains a challenge to the clinician. Recently, kinase inhibitors have shown great potential against fibrotic diseases and, specifically, the transforming growth factor-β receptor (TGF-βR) was found as a new and promising target for scleroderma therapy. In the current study, we propose that the large pool of existing kinase inhibitors could be exploited for inhibiting the TGF-βR to suppress scleroderma. In this respect, we developed a modeling protocol to systematically profile the inhibitory activities of 169 commercially available kinase inhibitors against the TGF-βR, from which five promising candidates were selected and tested using a standard kinase assay protocol. Consequently, two molecular entities, namely the PKB inhibitor MK-2206 and the mTOR C1/C2 inhibitor AZD8055, showed high potency when bound to the TGF-βR, with IC50 values of 97 and 86 nM, respectively, which are close to those of the recently developed TGF-βR selective inhibitors SB525334 and LY2157299 (IC50 = 14.3 and 56 nM, respectively). We also performed atomistic molecular dynamics simulations and post-molecular mechanics/Poisson-Boltzmann surface area analyses to dissect the structural basis and energetic properties of intermolecular interactions between the TGF-βR kinase domain and these potent compounds, highlighting intensive nonbonded networks across the tightly packed interface of non-cognate TGF-βR-inhibitor complexes.

TGF-β-induced expression of IGFBP-3 regulates IGF1R signaling in human osteosarcoma cells

Signaling pathways initiated by transforming growth factor-β (TGF-β) and insulin-like growth factors (IGFs) are important in osteosarcoma cell growth. We have investigated a role for endogenous IGF binding protein-3 (IGFBP-3) in mediating cross-talk between TGF-β receptor and type I IGF receptor (IGF1R) signaling pathways in MG-63 osteosarcoma cells. TGF-β1 indirectly activated the Ras/Raf/MAPK pathway and induced the expression of IGFBP-3, an important regulator of IGF1R activity. IGFBP-3 attenuated TGF-β1 activation of ERK1/2 and Akt in MG-63 cells, and inhibited TGF-β1-induced cell cycle progression and proliferation. This effect of IGFBP-3 was blocked by inhibiting IGF1R signaling. TGF-β1 phosphorylated Smad2 on the non-receptor substrate sites (Ser245/250/255). Blocking the TGF-β1-induced expression of IGFBP-3 enhanced pSmad2(Ser245/250/255) and increased its nuclear accumulation. These results suggest an important role for TGF-β1 in osteosarcoma cell growth, with the induction of IGFBP-3 by TGF-β1 serving in a negative-feedback loop to control cell growth by preventing activation of the IGF1R.