Search

Gall bladder cancer (GBC) is an aggressive and most common malignancy of biliary tract lacking effective treatment due to unavailability of suitable biomarkers and therapeutics. SMAD4 is an essential mediator of transforming growth factor-β pathway involved in various cellular processes like growth, differentiation and apoptosis and also recognized as therapeutic target for GBC and other gastrointestinal tract cancers. In the present study, 3D structure of SMAD4 mutants was optimized through molecular dynamics simulation (MDS) along with wildtype. Furthermore, binding site of protein was predicted through hybrid approach and structural based virtual screening against two drug libraries was performed followed by docking. MDS of top docking score protein-ligand complexes were carried, and binding free energy was rescored. Two potential inhibitors, namely ZINC2098840 and ZINC8789167, were screened that displayed higher binding affinity towards mutant proteins compared with wildtype and both hydrophilic as well as hydrophobic interactions play a crucial role during protein-ligand binding. Current study identified novel and potent inhibitors of SMAD4 mutant that could be used as a drug candidate for the development of personalized medicine for gall bladder and other associated cancers., (© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Osteoporosis is a metabolic disorder characterized by low bone mass and deteriorated microarchitecture, with an increased risk of fracture. Some miRNAs have been confirmed as potential modulators of osteoblast differentiation to maintain bone mass. Our miRNA sequencing results showed that miR-664-3p was significantly down-regulated during the osteogenic differentiation of the preosteoblast MC3T3-E1 cells. However, whether miR-664-3p has an impact on bone homeostasis remains unknown. In this study, we identified overexpression of miR-664-3p inhibited the osteoblast activity and matrix mineralization in vitro. Osteoblastic miR-664-3p transgenic mice exhibited reduced bone mass due to suppressed osteoblast function. Target prediction analysis and experimental validation confirmed Smad4 and Osterix (Osx) are the direct targets of miR-664-3p. Furthermore, specific inhibition of miR-664-3p by subperiosteal injection with miR-664-3p antagomir protected against ovariectomy-induced bone loss. In addition, miR-664-3p expression was markedly higher in the serum from patients with osteoporosis compared to that from normal subjects. Taken together, this study revealed that miR-664-3p suppressed osteogenesis and bone formation via targeting Smad4 and Osx. It also highlights the potential of miR-664-3p as a novel diagnostic and therapeutic target for osteoporotic patients., (© 2021 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.)

Bone morphogenetic proteins (BMPs) secreted by a variety of cell types are known to play essential roles in cell differentiation and matrix formation in the bone, cartilage, muscle, blood vessel, and neuronal tissue. BMPs activate intracellular effectors via C-terminal phosphorylation of Smad1, Smad5, and Smad9, which relay the signaling by forming a complex with Smad4 and translocate to the nucleus for transcriptional activation. Smad6 inhibits BMP signaling through diverse mechanisms operative at the membrane, cytosolic, and nuclear levels. However, the mechanistic underpinnings of Smad6 functional diversity remain unclear. Here, using a biochemical approach and cell differentiation systems, we report a cytosolic mechanism of action for Smad6 that requires arginine methylation at arginine 81 (R81) and functions through association with Smad1 and interference with the formation of Smad1-Smad4 complexes. By mutating the methylated arginine residue, R81, and by silencing the expression of protein arginine methyltransferase 1, we show that protein arginine methyltransferase 1 catalyzes R81 methylation of Smad6 upon BMP treatment, R81 methylation subsequently facilitates Smad6 interaction with the phosphorylated active Smad1, and R81 methylation facilitates Smad6-mediated interruption of Smad1-Smad4 complex formation and nuclear translocation. Furthermore, Smad6 WT but not the methylation-deficient R81A mutant inhibited BMP-responsive transcription, attenuated BMP-mediated osteogenic differentiation, and antagonized BMP-mediated inhibition of cell invasion. Taken together, our results suggest that R81 methylation plays an essential role in Smad6-mediated inhibition of BMP responses., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: Daphne mucronata Royle grown in Iran has shown anticancer activities against different cancer cell lines. Therefore, within this study, we investigate the phytochemical pattern of this plant., Method: Phytochemical investigation was done using standard column chromatography system: The structures were recognized by the interpretation of one and two-dimensional nuclear magnetic resonance (NMR) spectra and the help of High-Resolution Electrospray Ionization Mass spectroscopy (HR-ESIMS) and Infrared spectroscopy (IR) data. Stereochemistry was determined using 2D and 3D NOESY, and comparison of coupling constant values with literature. The absolute configuration was determined and confirmed using specific rotation and electronic circular dichroism experiments. Cytotoxicity was done against HeLa cells by standard MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Luciferase assay was used to check if the compounds can inhibit the activation of cancer-related signaling pathways. Molecular docking simulation was done for biological activity evaluation and to examine the interaction of the ligand with each of the proteins., Results: A new sesquiterpenoid, 4,11(12)-guiadiene-1-ol-3-one (4), together with eight specialized metabolites, betulinic acid (1), coniferyl aldehyde (2), oleanolic acid (3), daphnetoxin (5), apigenin (7), syringin (8), and genkwanol A (9) were isolated and reported for the first time from the shoots of the plant. Compound 4 as an undescribed compound was submitted for cytotoxicity assay and showed moderate activity with the IC 50 value of 51.3 ± 4.2 μM against HeLa cancer cells. It showed selective inhibition of Interleukin-6 mediated signal transducer and activator of transcription 3 pathway (STAT-3/ IL-6), and Smad protein / transforming growth factor beta (TGF-β) transcription factors when screened through an array of cancer signaling pathways. Molecular docking confirmed biological tests and showed the interaction with STAT3 and Smad proteins., Conclusion: An undescribed sesquiterpenoid: 4,11(12)-guiadiene-1-ol-3-one in addition to eight known compounds were isolated. The new sesquiterpene was evaluated for the luciferase assay on 14 main cancer-related signaling pathways and showed selective inhibition of STAT3/IL6, and Smad/ TGF-β transcription factors. Molecular docking simulation showed more interactions with STAT3 than Smad, which confirms better interaction of compound 4 with STAT3 than Smad proteins. Graphical abstract.

As a specific pearl mussel in China, Hyriopsis cumingii has enormous economic value. However, the organism damage caused by pearl insertion is immeasurable. TGF-β/Smad signal transduction pathways are involved in all phases of wound healing. We have previously reported on two cytoplasmic signal transduction factors, Smad3 and Smad5 in mussel H. cumingii (named HcSmads), suggesting their involvements in wound healing. Here, Smad4 was cloned and described. The full length cDNA of HcSmad4 was 2543 bp encoded 515 amino acids. Deduced HcSmad4 protein possessed conserved MH1 and MH2 domains, nuclear location signals (NLS), nuclear exput signals (NES) and Smad activation domain (SAD). Transcripts of Smad3, 4 and 5 were constitutively expressed in all detected tissues, at highest levels in muscles. Furthermore, HcSmad4 mRNA levels were significantly increased at incision site post wounding, and expression of downstream target genes of Smad4, such as HcMMP1, HcMMP19, HcTIMP1 and HcTIMP2 were upregulated to a certain extent. Whatever knocked down HcSmad3/4 or treated by specific inhibitors of Smad 3 (SIS3), expression levels of these genes displayed a significantly downregulated tendency compared with the wound group. In addition, histological evaluation suggested that Smad3 knockdown or SIS3 treatment was accelerated wound healing, and then Smad4 knockdown delayed the process of wound healing in mussels. These data implicate that Smad3/4 play an important role in tissue repair in mollusks., Competing Interests: Declaration of competing interest We declare that we have no conflict of interest., (Copyright © 2019. Published by Elsevier Ltd.)

As an important post-transcriptional regulatory machinery mediated by ∼21nt short-interfering double-stranded RNA (siRNA), RNA interference (RNAi) is a powerful tool to delineate gene functions and develop therapeutics. However, effective RNAi-mediated silencing requires multiple siRNAs for given genes, a time-consuming process to accomplish. Here, we developed a user-friendly system for single-vector-based multiplex siRNA expression by exploiting the unique feature of restriction endonuclease BstXI. Specifically, we engineered a BstXI-based shotgun cloning (BSG) system, which consists of three entry vectors with siRNA expression units (SiEUs) flanked with distinct BstXI sites, and a retroviral destination vector for shotgun SiEU assembly. For proof-of-principle studies, we constructed multiplex siRNA vectors silencing β-catenin and/or Smad4 and assessed their functionalities in mesenchymal stem cells (MSCs). Pooled siRNA cassettes were effectively inserted into respective entry vectors in one-step, and shotgun seamless assembly of pooled BstXI-digested SiEU fragments into a retroviral destination vector followed. We found these multiplex siRNAs effectively silenced β-catenin and/or Smad4, and inhibited Wnt3A- or BMP9-specific reporters and downstream target expression in MSCs. Furthermore, multiplex silencing of β-catenin and/or Smad4 diminished Wnt3A and/or BMP9-induced osteogenic differentiation. Collectively, the BSG system is a user-friendly technology for single-vector-based multiplex siRNA expression to study gene functions and develop experimental therapeutics.

Background: Hereditary hemorrhagic telangiectasia (HHT) is an inherited vascular disorder that causes arteriovenous malformations (AVMs). Mutations in the genes encoding Endoglin ( ENG) and activin-receptor-like kinase 1 ( AVCRL1 encoding ALK1) cause HHT type 1 and 2, respectively. Mutations in the SMAD4 gene are present in families with juvenile polyposis-HHT syndrome that involves AVMs. SMAD4 is a downstream effector of transforming growth factor-β (TGFβ)/bone morphogenetic protein (BMP) family ligands that signal via activin-like kinase receptors (ALKs). Ligand-neutralizing antibodies or inducible, endothelial-specific Alk1 deletion induce AVMs in mouse models as a result of increased PI3K (phosphatidylinositol 3-kinase)/AKT (protein kinase B) signaling. Here we addressed if SMAD4 was required for BMP9-ALK1 effects on PI3K/AKT pathway activation., Methods: The authors generated tamoxifen-inducible, postnatal, endothelial-specific Smad4 mutant mice ( Smad4 iΔEC )., Results: We found that loss of endothelial Smad4 resulted in AVM formation and lethality. AVMs formed in regions with high blood flow in developing retinas and other tissues. Mechanistically, BMP9 signaling antagonized flow-induced AKT activation in an ALK1- and SMAD4-dependent manner. Smad4 iΔEC endothelial cells in AVMs displayed increased PI3K/AKT signaling, and pharmacological PI3K inhibitors or endothelial Akt1 deletion both rescued AVM formation in Smad4 iΔEC mice. BMP9-induced SMAD4 inhibited casein kinase 2 ( CK2) transcription, in turn limiting PTEN phosphorylation and AKT activation. Consequently, CK2 inhibition prevented AVM formation in Smad4 iΔEC mice., Conclusions: Our study reveals SMAD4 as an essential effector of BMP9-10/ALK1 signaling that affects AVM pathogenesis via regulation of CK2 expression and PI3K/AKT1 activation.

MicroRNA (miRNA) is a sort of endogenous ~20-25 nt non-coding RNAs, and it can regulate a variety of biological events. We found the miR-378 may involve in regulating the muscle development of sheep during our previous research. However, the molecular mechanism of miR-378 regulating myoblast proliferation is still unclear. In this research, we predicted that BMP2 (Bone morphogenetic protein 2) was the target gene of miR-378 and the BMP-Smad signal pathway that BMP2 participated in playing an important role in the muscle development. Therefore, we tried to determine whether miR-378 influence myoblast proliferation of sheep through the BMP-Smad signal pathway. The results indicated that inhibit BMP-Smad signal pathway by interfering Smad4 to promote proliferation of sheep myoblasts; promote BMP-Smad signal pathway by interfering Smad7 to inhibit proliferation of sheep myoblasts; over-expression miR-378 promotes BMP-Smad signal pathway and myoblast proliferation in sheep; interfering miR-378 inhibits BMP-Smad signal pathway and myoblast proliferation in sheep. However, when both of which functioned at the myoblast, miR-378 could not fully depend on BMP-Smad signal pathway to regulate myoblast proliferation. In sum, both miR-378 and BMP-Smad can influence the proliferation of myoblast, but miR-378 does not target the 3' UTR of sheep BMP2., (Copyright © 2018. Published by Elsevier B.V.)

Epithelial-mesenchymal transition (EMT) is a key initial step in metastasis for malignant cancer cells to obtain invasive and motile properties. Inhibiting EMT has become a new strategy for cancer therapy. In our previous in vivo study, Nemopilema nomurai jellyfish venom (NnV) -treated HepG2 xenograft mice group showed that E-cadherin expression was strongly detected compared with non-treated groups. Therefore, this study aimed to determine whether NnV could inhibit the invasive and migratory abilities of HepG2 human hepatocellular carcinoma cells and to examine its effect on EMT. Our results revealed that transforming growth factor (TGF)-β1 induced cell morphological changes and downregulated E-cadherin and β-catenin expression, but upregulated N-cadherin and vimentin expression through the Smad and NF-κB pathways in HepG2 cells. Treatment of TGF-β1-stimulated HepG2 cells with NnV reversed the EMT-related marker expression, thereby inhibiting cell migration and invasion. NnV also significantly suppressed the activation of p-Smad3, Smad4, and p-NF-κB in a dose-dependent manner. These data indicated that NnV can significantly suppress cell migration and invasion by inhibiting EMT in HepG2 cells, and therefore might be a promising target for hepatocellular carcinoma therapeutics.

Background/aims: TGF-β1 is beneficial during early liver disease but is tumor-progressive during late stages especially for hepatocellular carcinoma (HCC). Thus, exploring the underlying mechanisms may provide information about a potentially therapeutic role of TGF-β1 in HCC., Methods: Western blot and real-time quantitative PCR were used to quantify FGFR4 expression in HCC cell lines and a normal liver cell line. After constructing the best silencing FGFR4 expression vector, migration and invasiveness of TGF-β1 in HCC was studied in vitro and in vivo. Western blot was used to study the mechanism of TGF-β1 induction on FGFR4 expression with various inhibitors., Results: HepG2 cell lines had the most FGFR4 expression, and data show that silencing FGFR4 suppressed cell proliferation, invasion and migration in HCC induced by TGF-β1 in vitro and in vivo. Moreover, TGF-β1 induced FGFR4 expression through the ERK pathway., Conclusion: Promoting FGFR4 expression via the ERK pathway, TGF-β1 contributes to HCC invasion and metastasis., (© 2018 The Author(s). Published by S. Karger AG, Basel.)

Colorectal cancer (CRC) is one of the most common malignant tumors of the digestive tract, and threatens the survival and health of patients with CRC. Chemotherapy remains one of the main therapeutic approaches for patients with CRC; however, drug resistance limits the long‑term use. CRC cells with multi‑drug resistance (MDR) exhibit increased survival times and metastatic potential, which may lead to the recurrence and metastasis of CRC. In addition, MDR is one of the major causes of chemotherapy failure in clinical treatment. Hedyotis diffusa Willd (HDW) has been used in the treatment of inflammation‑associated diseases and malignant tumors, including CRC. The authors previously demonstrated that HDW could reverse MDR in CRC cells; however, its underlying mechanism, particularly in MDR‑associated metastasis, remains to be elucidated. In the present study, the drug‑resistant CRC cell line HCT‑8/5‑fluorouracil (5‑FU) was used to investigate the effect of HDW on the growth and metastasis of cancer cells. Cell viability was assessed using the MTT assay. Cell adhesion potential was evaluated using adhesion experiments. Cell migration was assessed using wound healing and Transwell assays. The mRNA and protein expression levels of crucial factors in the transforming growth factor‑β (TGF‑β) signaling pathway, including TGF‑β, Mothers against decapentaplegic homolog 4 (SMAD4), neural (N)‑cadherin, and epithelial (E)‑cadherin, were analyzed using the reverse transcription‑semi‑quantitative polymerase chain reaction and western blotting, respectively. The results demonstrated that the HCT‑8/5‑FU cell line was more resistant to 5‑FU and thus can be used as the resistant cell model. HDW was able to inhibit the viability, and adhesive, migratory and invasion potential of the HCT‑8/5‑FU cells. In addition, HDW was able to downregulate the expression of TGF‑β, SMAD4 and N‑cadherin, and upregulate E‑cadherin, at the gene and protein level. In conclusion, the results demonstrated that HDW may suppress the metastasis of 5‑FU‑resistant CRC cells via regulation of the TGF‑β signaling pathway, which was also considered to be one of the underlying mechanisms of its anti‑CRC effect.

MicroRNA-124 (miR-124) has been shown to be downregulated in glioma; however, its biological functions in glioma are not yet fully understood. The aim of this study was to examine the Smad4‑dependent effects of miR‑124 on C6 glioma cell proliferation. In this study, the level of miR‑124 was found to be enhanced in C6 cells upon transfection with miR‑124 mimics, and the mechanisms of action of miR‑124 in C6 cells were investigated by reverse transcriptase-quantitative polymerase chain reaction, MTT assay, western blot analysis and luciferase reporter assays in vitro. The results revealed that miR‑124 expression was significantly lower in the C6 cells than in either normal rat brain tissue or astrocytes. Upon the overexpression of miR‑124, the proliferation of the C6 cells decreased and Smad4 expression was significantly suppressed. Smad4 was identified as a direct target of miR‑124 through luciferase reporter assays. Furthermore, miR‑124 was found to modulate signal transducer and activator of transcription 3 (Stat3) by downregulating Smad4 expression. Using small interfering RNA targeting Smad4 mRNA, we also confirmed that miR‑124 downregulated c‑Myc by modulating Smad4 expression. In addition, caspase‑3 expression was induced by miR‑124 overexpression, but not via Smad4 downregulation. On the whole, our results demonstrate that miR‑124 upregulation inhibits the growth of C6 glioma cells by targeting Smad4 directly. These findings may be clinically useful for the development of therapeutic strategies directed toward miR‑124 function in patients with glioma.

Polycystic ovary syndrome is a common endocrine disorder and a major cause of anovulatory sterility in women at reproductive age. Most patients with polycystic ovary syndrome have hyperandrogenism, caused by excess androgen synthesis. Bone morphogenetic protein 4 (BMP4) is an essential regulator of embryonic development and organ formation, and recent studies have also shown that BMP4 may be involved in female steroidogenesis process. However, the effect of BMP4 on hyperandrogenism remains unknown. Here, using a female mouse model of hyperandrogenism, we found that ovarian BMP4 levels were significantly decreased in hyperandrogenism. Elevated androgens inhibited BMP4 expression via activation of androgen receptors. Moreover, BMP4 treatment suppressed androgen synthesis in theca cells and promoted estrogen production in granulosa cells by regulating the expression of steroidogenic enzymes, including CYP11A , HSD3B2 , CYP17A1 , and CYP19A1 Consistently, knockdown of BMP4 augmented androgen levels and inhibited estrogen levels. Mechanistically, Smad signaling rather than the p38 MAPK pathway regulated androgen and estrogen formation, thereby mediating the effect of BMP4. Of note, BMP4-transgenic mice were protected against hyperandrogenism. Our observations clarify a vital role of BMP4 in controlling sex hormone levels and offer new insights into intervention for managing hyperandrogenism by targeting the BMP4-Smad signaling pathway., (© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.)

Understanding cancer stem cell (CSC) maintenance pathways is critical for the development of CSC-targeting therapy. Here, we investigated the functional role of the cyclin D1-dependent activation of Smad2/3 and Smad4 in hepatocellular carcinoma (HCC) CSCs and in HCC primary tumors. Cyclin D1 sphere-derived xenograft tumor models were employed to evaluate the therapeutic effects of a Smad inhibitor in combination with chemotherapy. Cyclin D1 overexpression confers stemness properties by enhancing single sphere formation, enhancing the CD90+ and EpCAM+ population, increasing stemness gene expression, and increasing chemoresistance. Cyclin D1 interacts with and activates Smad2/3 and Smad4 to result in cyclin D1-Smad2/3-Smad4 signaling-regulated liver CSC self-renewal. The cyclin D1-dependent activation of Smad2/3 and Smad4 is also found in HCC patients and predicts disease progression. A Smad inhibitor impaired cyclin D1-Smad-mediated self-renewal, resulting in the chemosensitization. Thus, pretreatment with a Smad inhibitor followed by chemotherapy not only successfully suppressed tumor growth but also eliminated 57% of the tumors in a cyclin D1 sphere-derived xenograft model. Together, The cyclin D1-mediated activation of Smad2/3 and Smad4 is an important regulatory mechanism in liver CSC self-renewal and stemness. Accordingly, a Smad inhibitor induced CSC differentiation and consequently significant chemosensitization, which could be an effective strategy to target CSCs.

Magnolol is a pharmacological biphenolic compound extracted from Chinese herb Magnolia officinalis, which displays anti-inflammatory and antioxidant effects. This study was aimed at exploring the potential effect of magnolol on immune-related liver fibrosis. Herein, BALB/c mice were injected with concanavalin A (ConA, 8 mg/kg/week) up to 6 weeks to establish hepatic fibrosis, and magnolol (10, 20, 30 mg/kg/day) was given to these mice orally throughout the whole experiment. We found that magnolol preserved liver function and attenuated liver fibrotic injury in vivo. In response to ConA stimulation, the CD4 + T cells preferred to polarizing towards CD4 + T helper 17 (Th17) cells in liver. Magnolol was observed to inhibit Th17 cell differentiation in ConA-treated liver in addition to suppressing interleukin (IL)-17A generation. Hepatic stellate cells were activated in fibrotic liver as demonstrated by increased alpha smooth muscle actin (α-SMA) and desmin. More transforming growth factor (TGF)-β1 and activin A were secreted into the serum. Magnolol suppressed this abnormal HSC activation. Furthermore, the phosphorylation of Smad3 in its linker area (Thr179, Ser 204/208/213) was inhibited by magnolol. In vitro, the recombinant IL-17A plus TGF-β1 or activin A induced activation of human LX2 HSCs and promoted their collagen production. Smad3/Smad4 signalling pathway was activated in LX2 cells exposed to the fibrotic stimuli, as illustrated by the up-regulated phospho-Smad3 and the enhanced interaction between Smad3 and Smad4. These alterations were suppressed by magnolol. Collectively, our study reveals a novel antifibrotic effect of magnolol on Th17 cell-mediated fibrosis., (© 2017 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).)

The mechanisms that regulate miR-574-3p expression in cells remain elusive. In the present study, we used real-time PCR assay to demonstrate TGF-β1-induced miR-574-3p upregulation in AGS cells, which was inhibited by TGF-β receptor I inhibitor SB431542. We used a computer search to identify Smad binding sites upstream of the miR-574-3p precursor sequence. We demonstrated that silencing Smad4, but not Smad2 or Smad3, significantly inhibited the TGF-β1-induced miR-574-3p upregulation in AGS cells. Furthermore, TGF-β1 significantly increased the activity of a dual-luciferase reporter that contains the Smad binding sites upstream of the miR-574 precursor sequence. Silencing Smad4 significantly inhibited the TGF-β1-induced increase in the activity of the reporter in AGS cells. ChIP assay showed that Smad4 directly bound to the promoter of miR-574-3p. MiR-574-3p inhibition was effective in eliminating the inhibition of AGS cell proliferation induced by TGF-β1, suggesting that TGF-β1 inducing upregulation of miR-574-3p is functionally significant., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The TGF-β/Smad signaling pathway plays important roles in cancer cell proliferation, apoptosis, differentiation, angiogenesis and epithelial-mesenchymal transition (EMT), which is the key event in the early stages of cancer metastasis and enhances the capability of cell migration and invasion. Smad4 acts as the only Co-Smad of TGF/Smad signaling pathway and plays the key role in TGF-β-mediated EMT. Nevertheless, the mRNA regulation mechanisms of Smad4 in human non-small cell lung cancer (NSCLC) remains largely unclear. Computational algorithms predicted that the 3'-UTR of Smad4 is a target of miR‑205. Here, we validated that miR‑205 could directly bind to 3'-UTR of Smad4 by luciferase assays. Moreover, we investigated the functional roles of miR‑205 and its molecular link to Smad4 in lung cancer cells. In this study, we confirmed that overexpression of miR‑205 suppressed the expression of Smad4, in turn, weakened the TGF-β/Smad signaling pathway and inhibited TGF-β/Smad4-induced EMT, invasion and migration ultimately. Furthermore, this study shows that miR‑205 can serve as a promising therapeutic target of highly aggressive NSCLC.

Background: Tumor metastasis is one of the leading causes of poor prognosis for colorectal cancer (CRC) patients. Loss of Smad4 contributes to aggression process in many human cancers. However, the underlying precise mechanism of aberrant Smad4 expression in CRC development is still little known., Results: miR-20a-5p negatively regulated Smad4 by directly targeting its 3'UTR in human colorectal cancer cells. miR-20a-5p not only promoted CRC cells aggression capacity in vitro and liver metastasis in vivo, but also promoted the epithelial-to-mesenchymal transition process by downregulating Smad4 expression. In addition, tissue microarray analysis obtained from 544 CRC patients' clinical characters showed that miR-20a-5p was upregulated in human CRC tissues, especially in the tissues with metastasis. High level of miR-20a-5p predicted poor prognosis in CRC patients., Methods: Five miRNA target prediction programs were applied to identify potential miRNA(s) that target(s) Smad4 in CRC. Luciferase reporter assay and transfection technique were used to validate the correlation between miR-20a-5p and Smad4 in CRC. Wound healing, transwell and tumorigenesis assays were used to explore the function of miR-20a-5p and Smad4 in CRC progression in vitro and in vivo. The association between miR-20a-5p expression and the prognosis of CRC patients was evaluated by Kaplan-Meier analysis and multivariate cox proportional hazard analyses based on tissue microarray data., Conclusions: miR-20a-5p, as an onco-miRNA, promoted the invasion and metastasis ability by suppressing Smad4 expression in CRC cells, and high miR-20a-5p predicted poor prognosis for CRC patients, providing a novel and promising therapeutic target in human colorectal cancer., Competing Interests: The authors declare no conflicts of interest.

As a key mediator of the transforming growth factor-beta (TGF-β) signaling pathway, which plays a pivotal role in regulating mammalian reproductive performance, Sma- and Mad-related protein 4 (SMAD4) is closely associated with the development of ovarian follicular. However, current knowledge of the genome-wide view on the role of SMAD4 gene in mammalian follicular granulosa cells (GCs) is still largely unknown. In the present study, RNA-Seq was performed to investigate the effects of SMAD4 knockdown by RNA interference (SMAD4-siRNA) in porcine follicular GCs. A total of 1025 differentially expressed genes (DEGs), including 530 upregulated genes and 495 downregulated genes, were identified in SMAD4-siRNA treated GCs compared with that treated with NC-siRNA. Furthermore, functional enrichment analysis indicated that upregulated DEGs in SMAD4-siRNA treated cells were mainly enriched in cell-cycle related processes, interferon signaling pathway, and immune system process, while downregulated DEGs in SMAD4-siRNA treated cells were mainly involved in extracellular matrix organization/disassembly, pathogenesis, and cell adhesion. In particular, cell cycle and TGF-β signaling pathway were discovered as the canonical pathways changed under SMAD4-silencing. Taken together, our data reveals SMAD4 knockdown alters the expression of numerous genes involved in key biological processes of the development of follicular GCs and provides a novel global clue of the role of SMAD4 gene in porcine follicular GCs, thus improving our understanding of regulatory mechanisms of SMAD4 gene in follicular development., (© 2016 Society for Reproduction and Fertility.)

One approach to identifying cancer-specific vulnerabilities and therapeutic targets is to profile genetic dependencies in cancer cell lines. Here, we describe data from a series of siRNA screens that identify the kinase genetic dependencies in 117 cancer cell lines from ten cancer types. By integrating the siRNA screen data with molecular profiling data, including exome sequencing data, we show how vulnerabilities/genetic dependencies that are associated with mutations in specific cancer driver genes can be identified. By integrating additional data sets into this analysis, including protein-protein interaction data, we also demonstrate that the genetic dependencies associated with many cancer driver genes form dense connections on functional interaction networks. We demonstrate the utility of this resource by using it to predict the drug sensitivity of genetically or histologically defined subsets of tumor cell lines, including an increased sensitivity of osteosarcoma cell lines to FGFR inhibitors and SMAD4 mutant tumor cells to mitotic inhibitors., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

Despite extensive research on osteoblast differentiation and proliferation in mesenchymal stem cells (MSCs), the accurate mechanism remains to be further elucidated. MicroRNAs have been reported to be key regulators of osteoblast differentiation and proliferation. Here, we found that miR-144-3p is down-regulated during osteoblast differentiation of C3H10T1/2 cells. Overexpression of miR-144-3p inhibited osteogenic differentiation, whereas inhibition of miR-144-3p reversed this process. Furthermore, miR-144-3p inhibited the proliferation of C3H10T1/2 cells by arresting cells at the G0/G1 phase. Results from bioinformatics analysis, luciferase assay and western blotting demonstrated that miR-144-3p directly targeted Smad4. Additionally, Smad4 knockdown blocks the effects of miR-144-3p inhibitor. Therefore, we conclude that miR-144-3p negatively regulates osteogenic differentiation and proliferation of C3H10T1/2 cells by targeting Smad4., (© 2016 Federation of European Biochemical Societies.)

Purposes: The epithelial-mesenchymal transition (EMT) plays an important role in cancer metastasis. Previous studies have reported that valproic acid (VPA) suppresses prostate carcinoma (PCa) cell metastasis and down-regulates SMAD4 protein levels, which is the key molecule in TGF-β-induced EMT. However, the correlation between VPA and the EMT in PCa remains uncertain., Methods: Markers of the EMT in PCa cells and xenografts were molecularly assessed after VPA treatment. The expression and mono-ubiquitination of SMAD4 were also analyzed. After transfection with plasmids that express SMAD4 or short hairpin RNA for SMAD4 down-regulation, markers of EMT were examined to confirm whether VPA inhibits the EMT of PCa cells through the suppression of SMAD4., Results: VPA induced the increase in E-cadherin (p < 0.05), and the decrease in N-cadherin (p < 0.05) and Vimentin (p < 0.05), in PCa cells and xenografts. SMAD4 mRNA and protein levels were repressed by VPA (p < 0.05), whereas the level of mono-ubiquitinated SMAD4 was increased (p < 0.05). SMAD4 knockdown significantly increased E-cadherin expression in PC3 cells, but SMAD4 over-expression abolished the VPA-mediated EMT-inhibitory effect., Conclusions: VPA inhibits the EMT in PCa cells via the inhibition of SMAD4 expression and the mono-ubiquitination of SMAD4. VPA could serve as a promising agent in PCa treatment, with new strategies based on its diverse effects on posttranscriptional regulation.

Doxorubicin (Dox) is a commonly used chemotherapeutic drug in human colon cancer. However, it becomes increasingly ineffective with tumor progression, the underlying mechanism of which remains to be elucidated. Emerging evidence has led to the identification of an association between chemoresistance and the acquisition of epithelial-mesenchymal transition (EMT) in cancer. However, it remains to be elucidated whether this process is involved in the development of resistance to Dox in colon cancer. In HCT116 human colon cancer cells treated with Dox (50 nmol/l), EMT was induced, and transforming growth factor (TGF)β signaling and multi-drug resistant plasma membrane glycoprotein levels were significantly increased. By contrast, silencing of Smad4, using stable RNA interference, inhibited TGFβ signaling, reversed the process of EMT and markedly increased the sensitivity of HCT116 cells to Dox. The results of the present study suggested that the combination of Dox with the downregulation of TGFβ signaling may be a potential novel therapeutic strategy with which to overcome chemoresistance during colon cancer chemotherapy.

Diabetic nephropathy is characterized by diffuse mesangial matrix expansion and is largely dependent on the TGF-β/Smad signaling pathway. Smad4 is required for TGF-β signaling; however, its regulation has not been well characterized in diabetic kidney disease. Here, we report that high glucose is sufficient to stimulate nuclear translocation of Smad4 in mesangial cells and that stimulation of the major energy sensor AMP-activated protein kinase (AMPK) has a potent effect to block Smad4 nuclear translocation. Activation of AMPK by 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) inhibited high glucose-induced and TGF-β stimulation of nuclear Smad4. To identify which of the catalytic α-subunits may be involved, small interfering (si) RNA-based inhibition of AMPK α1- or α2-subunit was employed. Inhibition of either subunit reduced overall AMPK activity and contributed to Smad4 nuclear accumulation. In an animal model of early diabetic kidney disease, induction of diabetes was found to markedly stimulate Smad4 protein levels and enhance nuclear accumulation. AMPK activation with AICAR completely prevented the upregulation of Smad4 and reduced mesangial matrix accumulation. We conclude that stimulation of Smad4 in cell culture and in in vivo models of early diabetic kidney disease is dependent on AMPK.

Cervical cancer is the major cause of cancer related deaths in women, especially in developing countries and Human Papilloma Virus infection in conjunction with multiple deregulated signaling pathways leads to cervical carcinogenesis. TGF-β signaling in later stages of cancer is known to induce epithelial to mesenchymal transition promoting tumor growth. Phytochemicals, curcumin and emodin, are effective as chemopreventive and chemotherapeutic compounds against several cancers including cervical cancer. The main objective of this work was to study the effect of curcumin and emodin on TGF-β signaling pathway and its functional relevance to growth, migration and invasion in two cervical cancer cell lines, SiHa and HeLa. Since TGF-β and Wnt/β-catenin signaling pathways are known to cross talk having common downstream targets, we analyzed the effect of TGF-β on β-catenin (an important player in Wnt/β-catenin signaling) and also studied whether curcumin and emodin modulate them. We observed that curcumin and emodin effectively down regulate TGF-β signaling pathway by decreasing the expression of TGF-β Receptor II, P-Smad3 and Smad4, and also counterbalance the tumorigenic effects of TGF-β by inhibiting the TGF-β-induced migration and invasion. Expression of downstream effectors of TGF-β signaling pathway, cyclinD1, p21 and Pin1, was inhibited along with the down regulation of key mesenchymal markers (Snail and Slug) upon curcumin and emodin treatment. Curcumin and emodin were also found to synergistically inhibit cell population and migration in SiHa and HeLa cells. Moreover, we found that TGF-β activates Wnt/β-catenin signaling pathway in HeLa cells, and curcumin and emodin down regulate the pathway by inhibiting β-catenin. Taken together our data provide a mechanistic basis for the use of curcumin and emodin in the treatment of cervical cancer.

Clinical studies showed that renal expression and serum levels of nerve growth factor (NGF) are increased in renal diseases characterized by progressive fibrosis, a pathologic process in which TGF-β1 mediates most of the key events leading to tubular epithelial-mesenchymal transition (EMT). However, the pathogenic role of high NGF levels has not yet been elucidated. In this study, we found that in tubular renal cells, HK-2, NGF transcriptionally up-regulated TGF-β1 expression and secretion and enhanced cell motility by activating EMT markers via its receptors, TrkA and p75(NTR). Interestingly, we observed that TGF-β1-SMAD pathway activation and the up-regulation of EMT markers NGF-induced were both prevented when knockdown of TGF-β1 gene occurred and that the pretreatment with an antibody anti-NGF reversed the nuclear translocation of pSMAD3/SMAD4 complex. Collectively, our results demonstrated that NGF promotes renal fibrosis via TGF-β1-signaling activation, suggesting that in kidney diseases high NGF serum levels could contribute to worsen renal fibrosis.

Background: Although few microRNAs (miRNAs) have been involved in the regulation of post-ischemic cardiac fibrosis, the exact effect and underlying mechanism of miRNAs in cardiac fibrosis remains unclear. Here, we sought to investigate whether microRNA-34 (miR-34) plays a role in the pathogenic development of myocardial fibrosis., Methods: The myocardial infarction (MI) mice model was induced and cardiac fibroblasts were cultured. Histological analyses, quantitative real-time polymerase chain reaction and Western blotting analysis were used., Results: We found that the miR-34 cluster, especially miR-34a, was upregulated in the MI heart. In vivo, inhibition of miR-34a reduces the severity of experimental cardiac fibrosis in mice. TGF-β1 increased miR-34a expression in cardiac fibroblasts. Overexpressing miR-34a levels increased the profibrogenic activity of TGF-β1 in cardiac fibroblast, whereas inhibition miR-34a levels weakened the activity. Finally, we showed that miR-34a's underlying mechanism during cardiac fibrosis occurs through the targeting of Smad4 expression., Conclusions: Our findings provide evidence that miR-34a plays a critical role in the progression of cardiac tissue fibrosis by directly targeting Smad4, which suggests that miR-34a may be new marker for cardiac fibrosis progression and that inhibition of miR-34a may be a promising strategy in the treatment of cardiac fibrosis.

Transforming growth factor beta (TGFbeta) superfamily signaling controls various aspects of female fertility. However, the functional roles of the TGFbeta-superfamily cognate signal transduction pathway components (e.g., SMAD2/3, SMAD4, SMAD1/5/8) in early embryonic development are not completely understood. We have previously demonstrated pronounced embryotrophic actions of the TGFbeta superfamily member-binding protein, follistatin, on oocyte competence in cattle. Given that SMAD4 is a common SMAD required for both SMAD2/3- and SMAD1/5/8-signaling pathways, the objectives of the present studies were to determine the temporal expression and functional role of SMAD4 in bovine early embryogenesis and whether embryotrophic actions of follistatin are SMAD4 dependent. SMAD4 mRNA is increased in bovine oocytes during meiotic maturation, is maximal in 2-cell stage embryos, remains elevated through the 8-cell stage, and is decreased and remains low through the blastocyst stage. Ablation of SMAD4 via small interfering RNA microinjection of zygotes reduced proportions of embryos cleaving early and development to the 8- to 16-cell and blastocyst stages. Stimulatory effects of follistatin on early cleavage, but not on development to 8- to 16-cell and blastocyst stages, were observed in SMAD4-depleted embryos. Therefore, results suggest SMAD4 is obligatory for early embryonic development in cattle, and embryotrophic actions of follistatin on development to 8- to 16-cell and blastocyst stages are SMAD4 dependent., (© 2014 by the Society for the Study of Reproduction, Inc.)

Thyroid transcription factor-1 (TTF-1, also known as NKX2-1) is a tissue-specific transcription factor in lung epithelial cells. Although TTF-1 inhibits the epithelial-to-mesenchymal transition induced by transforming growth factor-β (TGF-β) in lung adenocarcinoma cells, the mechanism through which TTF-1 inhibits the functions of TGF-β is unknown. Here we show that TTF-1 disrupts the nuclear Smad3-Smad4 complex without affecting the nuclear localization of phospho-Smad3. Genome-wide analysis by chromatin immunoprecipitation followed by sequencing revealed that TTF-1 colocalizes with Smad3 on chromatin and alters Smad3-binding patterns throughout the genome, while TTF-1 generally inhibits Smad4 binding to chromatin. Moreover, Smad3 binds to chromatin together with TTF-1, but not with Smad4, at some Smad3-binding regions when TGF-β signaling is absent, and knockdown of Smad4 expression does not attenuate Smad3 binding in these regions. Thus, TTF-1 may compete with Smad4 for interaction with Smad3, and in the presence of TTF-1, Smad3 regulates the transcription of certain genes independently of Smad4. These findings provide a new model of regulation of TGF-β-Smad signaling by TTF-1.

Previous studies have shown that disruption of the bone morphogenetic protein (BMP) signaling pathway is an important cause of intestinal cancer in human and animal models. Thus, the purpose of this study was to construct a Balb/C model of colorectal polyps. Pregnant mice at 9.5 days gestation were injected via the tail vein with the pSES-Si BMP4 plasmid bearing a fluorochrome (DsRed) reporter, in order to silence the BMP4 gene in the first generation (F1); this group of mice was named the pSES-BMP4 group Intestinal fluorescence was detected at 1-, 4- and 8-week‑old F1 mice, and reverse transcription-polymerase chain reaction (RT-PCR) and western-blotting assays were used to determine changes in the expression of BMP4. A dissecting microscope and hematoxylin and eosin (H&E) staining were used to observe the cell morphology and appearance of the polyps. DsRed fluorescence was observed in the intestines of 1-week-old F1 mice of the pSES-BMP4 group. BMP4 expression at the mRNA and protein level was reduced in 1-, 4- and 8-week-old F1 mice (P<0.05). However, the level of Smad4 mRNA was only reduced in 8-week-old F1 mice (P<0.05). Multiple hyperplasic polyps emerged in the colon and rectum of the intestines of 4-week-old F1 mice in the pSES-BMP4 group. The size of colorectal polyps increased at 8 weeks, when vessels and polyp pedicles became apparent. In conclusion, silencing of the BMP4 gene using transplacental RNAi injection can induce formation of colorectal polyps in mice.

Emerging evidence has demonstrated that chronic ethanol exposure induces iron overload, enhancing ethanol-mediated liver damage. The purpose of this study was to explore the effects of the naturally occurring compound quercetin on ethanol-induced iron overload and liver damage, focusing on the signaling pathway of the iron regulatory hormone hepcidin. Adult male C57BL/6J mice were pair-fed with isocaloric-Lieber De Carli diets containing ethanol (accounting for 30% of total calories) and/or carbonyl iron (0.2%) and treated with quecertin (100 mg/kg body weight) for 15 weeks. Mouse primary hepatocytes were incubated with ethanol (100 mM) and quercetin (100 μM) for 24 h. Mice exposed to either ethanol or iron presented significant fatty infiltration and iron deposition in the liver; these symptoms were exacerbated in mice cotreated with ethanol and iron. Quercetin attenuated the abnormity induced by ethanol and/or iron. Ethanol suppressed BMP6 and intranuclear SMAD4 as well as decreased hepcidin expression. These effects were partially alleviated by quercetin supplementation in mice and hepatocytes. Importantly, ethanol caused suppression of SMAD4 binding to the HAMP promoter and of hepcidin messenger RNA expression. These effects were exacerbated by anti-BMP6 antibody and partially alleviated by quercetin or human recombinant BMP6 in cultured hepatocytes. In contrast, co-treatment with iron and ethanol, especially exposure of iron alone, activated BMP6/SMAD4 pathway and up-regulated hepcidin expression, which was also normalized by quercetin in vivo. Quercetin prevented ethanol-induced hepatic iron overload different from what carbonyl iron diet elicited in the mechanism, by regulating hepcidin expression via the BMP6/SMAD4 signaling pathway., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The transforming growth factor beta (TGF-β) pathway plays key roles in development and cancer. TGF-β signaling converges on the Smad2 and Smad3 effectors, which can either cooperate or antagonize to regulate their transcriptional targets. Here we performed in vivo and in silico experiments to study how such cooperativity and antagonism might function during neurogenesis. In vivo electroporation experiments in the chick embryo neural tube show that Smad2 and Smad3 cooperate to promote neurogenesis, as well as the transcription of Smad3-specific targets. Knockdown of Smad2 enhances neurogenesis and the transcription of Smad3-specific targets. A mathematical model of the TGF-β pathway fits the experimental results and predicts that the proportions of the three different trimeric complexes formed dictates the transcriptional responses of the R-Smad proteins. As such, Smad2 targets are activated solely by the Smad2-Smad2-Smad4 complex, whereas Smad3 targets are activated both by Smad2-Smad3-Smad4 and Smad3-Smad3-Smad4 trimers. We have modeled the Smad responses onto arbitrary genes and propose that this mechanism might be extended to additional activities of TGF-β in development and disease.

The epithelial-to-mesenchymal transition (EMT) is important for the development of cancer metastases and organ fibrosis, conditions prevalent in aging. Because sirtuins affect the pathology of aging, we tested the effect of SirT1 on EMT. Reduced SIRT1 levels in HMLER breast cancer cells led to increased metastases in nude mice, and the loss of SIRT1 in kidney tubular epithelial cells exacerbated injury-induced kidney fibrosis. SIRT1 reduces EMT in cancer and fibrosis by deacetylating Smad4 and repressing the effect of TGF-β signaling on MMP7, a Smad4 target gene. Consequently, less E-cadherin is cleaved from the cell surface and β-catenin remains bound to E-cadherin at the cell-cell junctions. Our findings suggest that the SIRT1/Smad4/β-catenin axis may be a target for diseases driven by EMT., (Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.)

Bone morphogenetic proteins (BMPs) are known to play an important role in melanoma development and progression. However, the downstream targets of BMPs have not been investigated thus far. Therefore, we treated melanoma cell lines with the Smad-specific BMP inhibitor Dorsomorphin and performed a cDNA microarray. We identified death inducer-obliterator 1 (Dido1) as a BMP-specific Smad-regulated target gene, which was confirmed by qRT-PCR, immunofluorescence staining and electrophoretic mobility shift assay experiments. An analysis of Dido1 expression revealed an upregulation of Dido1 levels in melanoma cell lines and tissues compared with normal melanocytes. Colony-formation assays showed that siDido1-transfected cells formed significantly smaller colonies when grown in soft agar compared with control cells. In addition, fluorescence-activated cell sorting and western blot experiments revealed that transfection of melanoma cells with Dido1 small interfering RNAs led to an upregulation of apoptosis. Furthermore, cell migratory and invasive potentials were strongly reduced in siDido1-transfected cells compared with control cells. Finally, we demonstrated that Dido1 induces the expression of Integrin αV, thereby promoting the attachment, migration, invasion and apoptosis resistance of melanoma cells.

Vascular endothelial growth factor (VEGF) plays an important role in many disease states, including ischemia, chronic and acute inflammation, and pathologies associated with angiogenesis such as tumors and wounds. A number of factors regulate VEGF promoter activity and VEGF expression such as four and a half LIM domains 1 (FHL1) and Smad4. FHL1 belongs to a family of LIM-only proteins that regulate gene transcription, cell proliferation, differentiation and apoptosis. Smad4 is a tumor suppressor gene, initially identified as deleted in pancreatic carcinoma locus 4 (DPC4). The aim of this study was to determine whether FHL1 and Smad4 inhibited VEGF signaling. HepG2 cells were transfected with the VEGF-Luc reporter, Smad4 and FHL1 or Smad4 and FHL1 siRNA. Results showed that the overexpression of FHL1 and Smad4 synergistically inhibited the promoter activity, mRNA expression and secretion of VEGF, whereas knockdown of endogenous Smad4 and FHL1 had opposite effects. Moreover, the reduction of endogenous Smad4 eliminated FHL1-mediated inhibition of the VEGF promoter activity. In conclusion, a cooperative regulation of VEGF signaling by FHL1 and Smad4 was evidenced, which may provide a novel regulation mechanism underlying cancer development and progression.

Transforming growth factor β (TGFβ) is widely recognised as an important factor that regulates many steps of normal mammary gland (MG) development, including branching morphogenesis, functional differentiation and involution. Tif1γ has previously been reported to temporally and spatially control TGFβ signalling during early vertebrate development by exerting negative effects over SMAD4 availability. To evaluate the contribution of Tif1 γ to MG development, we developed a Cre/LoxP system to specifically invalidate the Tif1g gene in mammary epithelial cells in vivo. Tif1g-null mammary gland development appeared to be normal and no defects were observed during the lifespan of virgin mice. However, a lactation defect was observed in mammary glands of Tif1g-null mice. We demonstrate that Tif1 γ is essential for the terminal differentiation of alveolar epithelial cells at the end of pregnancy and to ensure lactation. Tif1 γ appears to play a crucial role in the crosstalk between TGFβ and prolactin pathways by negatively regulating both PRL receptor expression and STAT5 phosphorylation, thereby impairing the subsequent transactivation of PRL target genes. Using HC11 cells as a model, we demonstrate that the effects of Tif1g knockdown on lactation depend on both SMAD4 and TGFβ. Interestingly, we found that the Tif1γ expression pattern in mammary epithelial cells is almost symmetrically opposite to that described for TGFβ. We propose that Tif1γ contributes to the repression of TGFβ activity during late pregnancy and prevents lactation by inhibiting SMAD4.

Crosstalk of signaling pathways is critical during metazoan development and adult tissue homeostasis. Even though the transforming growth factor-beta (TGFβ) transduction cascade is rather simple, in vivo responsiveness to TGFβ ligands is tightly regulated at several steps. As such, TGFβ represents a paradigm for how the activity of one signaling system is modulated by others. Here, we report an unsuspected regulatory step involving Dishevelled (Dvl) and Par1b (also known as MARK2). Dvl and Par1b cooperate to enable TGFβ/bone morphogenetic protein (BMP) signaling in Xenopus mesoderm development and TGFβ responsiveness in mammalian cells. Mechanistically, the assembly of the Par1b/Dvl3/Smad4 complex is fostered by Wnt5a. The association of Smad4 to Dvl/Par1 prevents its inhibitory ubiquitination by ectodermin (also known as transcriptional intermediary factor 1 gamma or tripartite motif protein 33). We propose that this crosstalk is relevant to coordinate TGFβ responses with Wnt-noncanonical and polarity pathways.

The transforming growth factor-β (TGF-β) signalling pathway participates in various biological processes. Dysregulation of Smad4, a central cellular transducer of TGF-β signalling, is implicated in a wide range of human diseases and developmental disorders. However, the mechanisms underlying Smad4 dysregulation are not fully understood. Using a functional screening approach based on luciferase reporter assays, we identified 39 microRNAs (miRNAs) as potential regulators of Smad4 from an expression library of 388 human miRNAs. The screening was supported by bioinformatic analysis, as 24 of 39 identified miRNAs were also predicted to target Smad4. MiR-199a, one of the identified miRNAs, was inversely correlated with Smad4 expression in various human cancer cell lines and gastric cancer tissues, and repressed Smad4 expression and blocked canonical TGF-β transcriptional responses in cell lines. These effects were dependent on the presence of a conserved, but not perfect seed paired, miR-199a-binding site in the Smad4 3'-untranslated region (UTR). Overexpression of miR-199a significantly inhibited the ability of TGF-β to induce gastric cancer cell growth arrest and apoptosis in vitro, and promoted anchorage-independent growth in soft agar, suggesting that miR-199a plays an oncogenic role in human gastric tumourigenesis. In conclusion, our functional screening uncovers multiple miRNAs that regulate the cellular responsiveness to TGF-β signalling and reveals important roles of miR-199a in gastric cancer by directly targeting Smad4.

Introduction: miR-146a is one of the first identified miRNAs expressed differentially in osteoarthritis (OA) cartilage. However, the role it plays in OA pathogenesis is not clear. The aim of this study is to identify a molecular target of miR-146a, thereby elucidating its function in chondrocytes during OA pathogenesis., Methods: Primary chondrocytes from Sprague-Dawley rats were treated with IL-1β before the expression levels of miR-146a, Smad4 and vascular endothelial growth factor (VEGF) were quantified by real-time PCR and/or western blotting. The effect of miR-146a on cellular response to transforming growth factor (TGF)-β1 was quantified by a luciferase reporter harboring TGF-β1 responsive elements and by extracellular signal-regulated kinase assay. The effect of miR-146a on apoptosis was quantified by the TUNEL assay. OA pathogenesis was surgically induced with joint instability in rats, evaluated by histopathological analysis with safranin O staining, and the expression levels of miR-146a, Smad4, and VEGF were quantified using real-time PCR and/or immunohistochemistry., Results: IL-1β treatment of chondrocytes increased the expression levels of miR-146a and VEGF and decreased the levels of Smad4 in a time-dependent manner. miR-146a upregulated VEGF expression and downregulated Smad4 expression in chondrocytes, while a miR-146a inhibitor acted in a converse manner. Smad4, a common mediator of the TGF-β pathway, is identified as a direct target of miR-146a by harboring a miR-146a binding sequence in the 3'-UTR region of its mRNA. Mutation of the binding sequence significantly relieved the inhibition of the Smad4 reporter activity by miR-146a. Furthermore, miR-146a upregulation of VEGF is mediated by Smad4. Expression of miR-146a led to a reduction of cellular responsiveness to TGF-β and an increase of apoptosis rate in chondrocytes. In vivo, cartilage from surgically induced OA rats displayed higher levels of miR-146a and VEGF compared with the sham group. In contrast, Smad4 expression level was lower in the OA group than the sham group., Conclusion: IL-1β responsive miR-146a is overexpressed in an experimentally induced OA model, accompanied by upregulation of VEGF and downregulation of Smad4 in vivo. miR-146a may contribute to OA pathogenesis by increasing VEGF levels and by impairing the TGF-β signaling pathway through targeted inhibition of Smad4 in cartilage.

Elongation and elevation of palatal shelves, mainly caused by proliferation and extra-cellular matrix synthesis of palatal mesenchymal cells (PMCs), are essential for normal palatal development. Transforming growth factor beta (TGFB) pathway could induce proliferation inhibition and collagen synthesis in PMCs. Recent studies found that miRNA-17-92 (miR-17-92) cluster, including miR-17, miR-18a, miR-19a, miR-20a, miR-19b, and miR-92a, expressed in the 1st bronchial arch of mouse embryos during the period of palatal shelf elongation and elevation, and directly targeted TGFB pathway in cancer cell lines. Whether miR-17-92 cluster expresses and targets TGFB pathway in PMCs has not yet been studied. Using quantitative real-time RT-PCR, we found that miR-17-92 expressed in PMCs and decreased from embryonic day (E) 12 to E14 in palatal shelves. MTT assay and Western blot showed that miR-17-92 inhibited TGFB1 induced proliferation inhibition and collagen synthesis in PMCs by decreasing TGFBR2, SMAD2, and SMAD4 protein level. Further luciferase assay showed that miR-17 and miR-20a directly targeted 3′UTR of TGFBR2, and that miR-18a directly targeted 3′UTR of SMAD2 and SMAD4. We thus conclude that miR-17-92 cluster could inhibit TGFB pathway induced proliferation inhibition and collagen synthesis in PMCs by directly targeting TGFBR2, SMAD2, and SMAD4., (© 2011 Wiley Periodicals, Inc.)

The aim of this study was to determine whether the suppression of Smad4 by short hairpin RNA (shRNA) regulates the proliferation and invasion of colorectal carcinoma HCT116 cells and Id2 expression. The Smad4‑shRNA expression vectors were constructed and stably transfected to HCT116 cells. The expression of mRNA and protein of Smad4 and Id2 was detected using reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting. Cellular proliferation inhibitory activity was determined by methyl thiazolyl tetrazolium (MTT) assay. Transwell assay was used to detect the effect of the inhibition of Smad4-shRNA on migration and invasion. The Smad4-shRNA vector, which inhibited Smad4 expression, was constructed and successfully transfected to HCT116 cells. The levels of mRNA and protein expression of Smad4 were markedly decreased following transfection of shRNA compared with the control groups (P<0.05). The abilities of proliferation, migration and invasion were increased following transfection of shRNA (P<0.05). The expression of Id2 was increased following transfection of shRNA (P<0.05). For the Smad4-down-regulated HCT116 cells, treated with or without BMP7 (25 ng/ml), no difference was found. shRNA-mediated silencing of Smad4 was able to enhance the abilities of proliferation, migration and invasion in the HCT116 cell line. Therefore, Smad4 may act as a tumor-suppressor gene in colorectal carcinoma.

Cyclooxygenase (COX)-2 is a key regulatory enzyme in the production of prostaglandins (PG) during various physiological processes. Mechanisms of COX-2 regulation in human endometrial stromal cells (human endometrial stromal cells) are not fully understood. In this study, we investigate the role of TGF-β in the regulation of COX-2 in human uterine stromal cells. Each TGF-β isoform decreases COX-2 protein level in human uterine stromal cells in Smad2/3-dependent manner. The decrease in COX-2 is accompanied by a decrease in PG synthesis. Knockdown of Smad4 using specific small interfering RNA prevents the decrease in COX-2 protein, confirming that Smad pathway is implicated in the regulation of COX-2 expression in human endometrial stromal cells. Pretreatment with 26S proteasome inhibitor, MG132, significantly restores COX-2 protein and PG synthesis, indicating that COX-2 undergoes proteasomal degradation in the presence of TGF-β. In addition, each TGF-β isoform up-regulates endoplasmic reticulum (ER)-mannosidase I (ERManI) implying that COX-2 degradation is mediated through ER-associated degradation pathway in these cells. Furthermore, inhibition of ERManI activity using the mannosidase inhibitor (kifunensine), or small interfering RNA-mediated knockdown of ERManI, prevents TGF-β-induced COX-2 degradation. Taken together, these studies suggest that TGF-β promotes COX-2 degradation in a Smad-dependent manner by up-regulating the expression of ERManI and thereby enhancing ER-associated degradation and proteasomal degradation pathways.

DPC4 (deleted in pancreatic cancer 4)/Smad4 is an essential factor in transforming growth factor (TGF)-β signaling and is also known as a frequently mutated tumor suppressor gene in human pancreatic and colon cancer. However, considering the fact that TGF-β can contribute to cancer progression through transcriptional target genes, such as Snail, MMPs, and epithelial-mesenchymal transition (EMT)-related genes, loss of Smad4 in human cancer would be required for obtaining the TGF-β signaling-independent advantage, which should be essential for cancer cell survival. Here, we provide the evidences about novel role of Smad4, serum-deprivation-induced apoptosis. Elimination of serum can obviously increase the Smad4 expression and induces the cell death by p53-independent PUMA induction. Instead, Smad4-deficient cells show the resistance to serum starvation. Induced Smad4 suppresses the PAK1, which promotes the PUMA destabilization. We also found that Siah-1 and pVHL are involved in PAK1 destabilization and PUMA stabilization. In fact, Smad4-expressed cancer tissues not only show the elevated expression of PAK1, but also support our hypothesis that Smad4 induces PUMA-mediated cell death through PAK1 suppression. Our results strongly suggest that loss of Smad4 renders the resistance to serum-deprivation-induced cell death, which is the TGF-β-independent tumor suppressive role of Smad4.

Background: Wilms' tumor suppressor gene (WT1) is essential for normal podocyte function, and transforming growth factor (TGF)-beta contributes to focal segmental glomerulosclerosis (FSGS). We aimed to address whether TGF-beta affects WT1 expression in podocytes., Methods: A human podocyte cell line treated with TGF-beta1 and kidneys in Alb/TGF-beta1-transgenic mice were analyzed for WT1 expression., Results: In cultured podocytes, TGF-beta1 reduced WT1 protein expression determined by western blotting beginning at 8 h and decreased WT1 messenger RNA (mRNA) expression measured by quantitative reverse transcription-polymerase chain reaction beginning at 3 h. Knockdown of Smad4 by small hairpin (sh) RNA partially rescued the TGF-beta1-induced reduction of both WT1 protein and mRNA expressions in the cultured podocytes. TGF-beta1 did not alter luciferase activity of the reporter construct for a human WT1 promoter but reduced that for a human WT1 5' enhancer construct, suggesting that TGF-beta1 may regulate WT1 expression by altering the 5' enhancer activity. In the transgenic mice, WT1 protein expression in podocytes was decreased at 1 and 3 weeks of age, while glomeruloclerosis developed after 3 weeks., Conclusion: TGF-beta1 reduces WT1 expression in cultured human podocytes and podocytes in mice before overt glomerulosclerosis begins. The effects are at least partially Smad4 dependent. Our findings identify a novel pathway linking TGF-beta1 to podocyte injury and FSGS. The WT1 reduction may be a useful marker for early podocyte injury.

Background: Proteinase-activated receptor 2 (PAR2) is a G-protein-coupled receptor that is activated by several serine proteases. PAR2 activation in endometriotic stromal cells (ESCs) has been implicated in the development of endometriosis but the regulatory mechanism of PAR2 expression in ESC is unknown. Our objective was to study the mechanism by which PAR2 expression may be regulated in endometriotic lesions., Methods: Primary cultures of ESCs were treated with transforming growth factor-β (TGF-β) 1, tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), and the expression of PAR2 was examined by real-time quantitative PCR. ESCs pretreated with or without TGF-β1 were treated with PAR2 agonist peptide (PAR2AP) and the secretion of the pro-endometriotic cytokine, IL-6, was measured using a specific enzyme-linked immunosorbent assay. Effects of TGF-β type 1 inhibitor, SB431542, and PAR2 small interfering RNA (siRNA) on the TGF-β1 stimulation of PAR2 gene expression and PAR2AP-induced IL-6 secretion were also evaluated. To study intracellular signaling, effects of inhibitors of mitogen-activated protein kinases (MAPKs) and phosphoinositide 3-kinase (PI3K) and of Smad4 siRNA on the TGF-β1-induced PAR2 gene expression were studied., Results: Only TGF-β1, but neither TNF-α nor IL-1β, increased gene expression of PAR2. Activation of PAR2 with PAR2AP increased the secretion of IL-6 from ESCs. As expected, TGF-β1 pretreatment dose-dependently enhanced the PAR2AP-induced increase in IL-6 secretion from ESCs. Treatment of ESCs with the TGF-β type 1 inhibitor, SB431542, inhibited both TGF-β1-stimulation of PAR2 gene expression and PAR2AP-induced IL-6 secretion. Transfection of ESCs with PAR2 siRNA produced a similar inhibition of IL-6 secretion. The TGF-β1-induced increase in PAR2 gene expression was repressed by inhibition of p38 MAPK, p42/44 MAPK or PI3K, but not by knockdown of Smad4 expression., Conclusions: In view of significant roles of PAR2 and IL-6 in endometriosis, the TGF-β1-induced increase in PAR2 expression may be an elaborate mechanism that augments the progression of the disease.

S100A8 and its dimerization partner S100A9 are emerging as important chemokines in cancer. We previously reported that Smad4-negative pancreatic tumors contain fewer stromal S100A8-positive monocytes than their Smad4-positive counterparts. Here, we studied S100A8/A9-expressing cells in colorectal tumors relating their presence to clinicopathological parameters and Smad4 status. Two-dimensional gel electrophoresis (n = 12) revealed variation in the levels of S100A8 protein in colorectal cancer tumors, whereas immunohistochemical analysis (n = 313) showed variation in the numbers of stromal S100A8-positive and S100A9-positive cells. Loss of Smad4 expression was observed in 42/304 (14%) colorectal tumors and was associated with reduced numbers of S100A8-positive (P = 0.03) but not S100A9-positive stromal cells (P = 0.26). High S100A9 cell counts were associated with large tumor sizes (P = 0.0006) and poor differentiation grade (P = 0.036). However, neither S100A8 nor S100A9 cell counts predicted poor survival, except for patients with Smad4-negative tumors (P = 0.02). To address the impact of environmental S100A8/A9 chemokines on tumor cells, we examined the effects of exogenously added S100A8 and S100A9 proteins on cellular migration and proliferation of colorectal and pancreatic cancer cells. S100A8 and S100A9 enhanced migration and proliferation in Smad4-positive and Smad4-negative cancer cells. However, transient depletion of Smad4 resulted in loss of responsiveness to exogenous S100A8, but not S100A9. S100A8 and S100A9 activated Smad4 signaling as evidenced by phosphorylation of Smad2/3; blockade of the receptor for the advanced glycation end products inhibited this response. In conclusion, Smad4 loss alters the tumor's interaction with stromal myeloid cells and the tumor cells' response to the stromal chemokine, S100A8.

Pancreatic ductal adenocarcinoma (PDAC) represents the eighth frequent solid tumor and fourth leading cause of cancer death. Because current treatments against PDAC are still unsatisfactory, new anticancer strategies are required, including oncolytic viruses. Among these, autonomous parvoviruses (PV), like MVMp (minute virus of mice) and H-1PV are being explored as candidates for cancer gene therapy. Human PDAC cell lines were identified to display various susceptibilities to an infection with H-1PV. The correlation between the integrity of the transcription factor SMAD4, mutated in 50% of all PDAC, and H-1PV permissiveness was particularly striking. Indeed, mutation or deletion of SMAD4 dramatically reduced the activity of the P4 promoter and, consequently, the accumulation of the pivotal NS1 protein. By means of DNA affinity immunoblotting, novel binding sites for SMAD4 and c-JUN transcription factors could be identified in the P4 promoter of H-1PV. The overexpression of wild-type SMAD4 in deficient cell lines (AsPC-1, Capan-1) stimulated the activity of the P4 promoter, whereas interference of endogenous SMAD4 function with a dominant-negative mutant decreased the viral promoter activity in wild-type SMAD4-expressing cells (Panc-1, MiaPaCa-2) reducing progeny virus production. In conclusion, the importance of members of the SMAD family for H-1PV early promoter P4 activity should guide us to select SMAD4-positive PDACs, which may be possible targets for an H-1PV-based cancer therapy.

Epithelial-mesenchymal-transition (EMT) in response to TGFβ contributes to normal development, wound healing and tumor progression. The present study provides evidence for a critical role of β5-integrin in the TGFβ-induced EMT and the tumorigenic potential of carcinoma cells. We show that the αvβ-integrin subunits are upregulated during the TGFβ-induced EMT and this response requires Smad transcription factors. Depletion of αv-integrin by siRNA blocked the EMT response whereas knock-down of β1-integrin had no effect. Importantly, depletion of β5-integrin blocked the TGFβ-induced EMT impairing adhesion to cell-matrix and integrin signaling, but did not change expression of E-cadherin and TGFβ-target genes. Accordingly, the EMT process and integrin signaling were blocked by cRGD peptide interfering with cell-matrix adhesion or by inhibition of focal adhesion kinase, indicating the importance of β5-integrin-mediated adhesions in EMT. Finally, depletion of β5-integrin significantly reduced invasiveness of breast carcinoma cells. Thus, the β5-integrin adhesions contribute to the TGFβ-induced EMT and the tumorigenic potential of carcinoma cells.

Heterotopic ossification of muscles, tendons and ligaments are a common problem affecting patient with trauma or received elective surgery. But the existing preventive or therapeutic methods all have disadvantages. Runt-related protein 2 (Runx2) and Smad4 are two regulators that have important roles in the differentiation of osteoblast. In this study, we attempted to examine the effect of Runx2 and Smad4 on the development of heterotopic ossification in vitro. We constructed non-virus-containing small interference RNAs (siRNAs) against Runx2 and Smad4 and tested it with reverse transcriptase-PCR and western blot. We then analyzed the independent effect of Runx2- and Smad4-specific siRNAs and their cooperative effect on the formation of heterotopic ossification induced by trauma in rats. The effects were measured with computed tomography scanning, hematoxylin and eosin staining and immunohistochemistry. We found that the Runx2- and Smad4-specific siRNAs inhibited the expression of Runx2 and Smad4 at the level of messenger RNA and protein. Runx2 and Smad4 independently inhibited the formation of heterotopic ossification. Moreover, their co-expression significantly enhanced the inhibition of heterotopic ossification compared with the independent effect. We suggest that gene therapy to inhibit Runx2 and Smad4 by RNAi could be a powerful approach to prevent or treat heterotopic ossification.

TGF-beta plays an important role in regulating cell differentiation and proliferation in human cancers such as colorectal cancer. Id-1 has been identified as a marker in colorectal cancer progression. The aim of this study was to investigate the role of TGF-beta in regulating Id-1 in LoVo cells. siRNA was used to silence smad2, smad3, and p38 MAPK gene expression in Lovo cells. Interference efficiency and the role of TGF-beta on Id-1 expression were analyzed using a luciferase reporter assay, RT-PCR, and Western blotting. Cell viability was determined using the MTT assay. In this study, we demonstrated that TGF-beta1 downregulated Id-1 protein expression in LoVo cells. Smad2 and smad3 siRNA inhibited TGF-beta1-induced 4xSBE luciferase reporter activity. p38 MAPK siRNA inhibited TGF-beta1-induced 3xAP-1 luciferase reporter activity. However, the suppression of Id-1 by TGF-beta1 was recovered by smad3 siRNA but not smad2 or p38 MAPK siRNA. Moreover, TGF-beta1 stimulated cellular proliferation and p21(Waf1) protein expression, which might be mediated by suppressing Id-1 expression. In conclusion, this study demonstrated that TGF-beta1 suppressed Id-1 expression in a smad3-dependent manner in LoVo cells using RNAi technology. These results provide new insight into the mechanisms of TGF-beta function in colorectal cancer cells., ((c) 2009 Wiley-Liss, Inc.)