Role Of Smad3 Research Articles

Role of Smad4 from ocular surface ectoderm in retinal vasculature development.

To investigate how signals from lens regulate retinal vascular development and neovascularization. Le-Cre transgenic mouse line was employed to inactivate Smad4 in the surface ectoderm selectively. Standard histological and whole-mount retina staining were employed to reveal morphological changes of retinal vasculature in Smad4 defective eye. cDNA microarray and subsequent analyses were conducted to investigate the molecular mechanism underlying the vascular phenotype. Quantitative polymerase chain reaction (qPCR) was carried out to verify the microarrays results. We found that inactivation of Smad4 specifically on surface ectoderm leads to a variety of retinal vasculature anomalies. Microarray analyses and qPCR revealed that Sema3c, Sema3e, Nrp1, Tie1, Sox7, Sox17, and Sox18 are significantly affected in the knockout retinas at different developmental stages, suggesting that ocular surface ectoderm-derived Smad4 can signal to the retina and regulates various angiogenic signaling in the retina. Our data suggest that the cross-talk between ocular surface ectoderm and retina is important for retinal vasculature development, and Smad4 regulates various signaling associated with sprouting angiogenesis, vascular remodeling and maturation in the retina of mice.

SMAD4 Y353C promotes the progression of PDAC

BackgroundSMAD4 is frequently inactivated and associated with a poor prognosis in pancreatic ductal adenocarcinoma (PDAC). Abnormal SMAD4 expression also plays an important role in the malignant progression of PDAC.MethodsWe investigated SMAD4 status in PDAC by immunohistochemical methods to explore the relationships between SMAD4 expression and clinicopathological features and then detected SMAD4 mutations by Sanger sequencing in 95 patients with PDAC to identify new mutation sites in PDAC. We further evaluated the effects of a missense mutation, Y353C, in the SMAD4 MH2 domain, on cell proliferation and migration in vitro.ResultsImmunohistochemistry showed that the expression of SMAD4 in PDAC carcinoma tissue was significantly lower than that in normal pancreatic tissue, and negative SMAD4 expression was closely related to tumour diameter, staging, lymph node metastasis and differentiation. Sanger sequencing analysis showed that the rate of SMAD4 mutation was 11.8% in 85 PDAC cases, and the novel SMAD4 Y353C missense mutation identified in this study promoted cell migration and invasion without affecting cell proliferation in vitro. Furthermore, SMAD4 Y353C resulted in reduced expression of E-cadherin and increased expression of Vimentin compared with wild-type SMAD4 overexpression.ConclusionThis study supports the key role of SMAD4 as a tumour suppressor gene in PDAC and shows that SMAD4 Y353C is associated with poor progression of PDAC.

Airway Epithelial Genomic Signatures in Steroid-Resistant COPD; Role for SMAD3 in Vascular Remodeling in Pulmonary Hypertension; Regulation of Lung Endothelial Cell Function by VEGFR3.

Airway Epithelial Genomic Signatures in Steroid-Resistant COPD; Role for SMAD3 in Vascular Remodeling in Pulmonary Hypertension; Regulation of Lung Endothelial Cell Function by VEGFR3.

Increased Smad3 and reduced Smad2 levels mediate the functional switch of TGF-β from growth suppressor to growth and metastasis promoter through TMEPAI/PMEPA1 in triple negative breast cancer.

Screening of several TNBC cell lines showed altered Smad2 and Smad3 protein levels compared to normal mammary epithelial cells, suggesting the possibility that it could play an important role in the escape of cancer cells from TGF-β mediated growth inhibition. To assess the functional relevance of these endogenous molecules, Smad2 or Smad3 expression was knocked down individually and assessed their effects on pro-oncogenic properties of TGF-β. Smad3 deficiency reduced growth and invasion capacity of breast cancer cells in comparison to Smad2 which had no effect. Smad3 deficiency was also found to be associated with a reduction in the expressions of TMEPAI/PMEPA1 and EMT inducing transcription factors, E-Cadherin and increased expression of cell cycle inhibitors and Vimentin. On the other hand, Smad2 deficiency had opposite effect on these regulators. Interestingly, the decreased growth, invasion and associated gene expressions were largely reversed by overexpressing TMEPAI in Smad3 knockdown cells, suggesting that Smad3-TMEPAI axis may be involved in subverting growth suppressive effects of TGF-β into growth promotion. Similarly, altered levels of Smad proteins and TMEPAI were also noted in primary TNBC tumor tissues. Analysis of the existing databases provided additional support in terms of TMEPAI and Smad2 expression impacting the survival of TNBC patients. Taken together, our data demonstrate a novel role for Smad3 in cancer transformation and cancer progression through TMEPAI and further suggest that selective targeting of TGF-β-Smad3-TMEPAI axis may be beneficial in triple negative breast cancer therapy and prevention.

Expression of miR-15b-5p, miR-21-5p, and SMAD7 in Lung Tissue of Sulfur Mustard-exposed Individuals with Long-term Pulmonary Complications.

Sulfur mustard (SM)-exposed individuals develop late pulmonary complications, which are associated with chronic inflammation and fibrotic changes in the lung tissue. MicroRNAs are known to act as important regulators of inflammatory responses, including inflammation and fibrosis-related cytokine signaling. In this study, we investigated the expression miR-15b-5p and miR-21-5p, two regulators of TGF-β signaling, as well as their target molecule, SMAD7, in lung tissues from SM-exposed and control individuals. Total RNA was extracted from formalin-fixed paraffin-embedded (FFPE) lung tissue biopsies obtained during surgery from SM-exposed (n=20) or control (n=20) cases. Quality of the extracted RNA was evaluated by an Agilent Bioanalyzer and RNA was quantified using a NanoDrop. MiR-21-5p, miR-15b-5p and SMAD7 expression levels were measured by real-time RT-PCR. miR-21-5p expression levels were significantly decreased (2.7 fold) in the lung tissues from SM-exposed individuals compared with tissues obtained from the control group (p=0.02). There were no significant differences in miR-15b-5p expression levels between the two groups (p=0.94). Interestingly, SMAD7 expression levels were significantly higher (5.8 fold) in SM-exposed individuals' lung tissues compared with the control group (p=0.045). Our data indicate that exposure to sulfur mustard affects the expression of miR-21-5p as well as its target, SMAD7, in lung tissues many years after exposure. Considering the role of SMAD7 in the regulation of TGF-β signaling, these changes might point to a potential mechanism by which SM-exposure regulates inflammatory/fibrotic alterations in lung tissue.

Enhancement of gemcitabine cytotoxicity in pancreatic adenocarcinoma through controlled release of nitric oxide.

Gemcitabine (GEM) is the first-line treatment for pancreatic adenocarcinoma (PAC) yet chemoresistance is common. Nitric oxide (NO) is the predominant species responsible for the cytotoxic action of macrophages against cancer cells yet localized delivery is difficult given the short half-life. We sought to study the effect of locally delivered NO on GEM mediated PAC cytotoxicity and the potential role of SMAD4 in this effect. We hypothesized that NO would enhance the cytotoxicity of GEM in a SMAD4 dependent manner. NO-Silica nanoparticles (NO-Si) were synthesized via a co-condensation of tetraethoxysilane with aminoalkoxysilane under high-pressure nitrous oxide. NO release was measured using chemiluminescence. A SMAD4 negative PAC cell line (SMAD4-) was made using retroviral knockdown of Panc1 PAC cells. Panc1 and SMAD4- cells were treated with gemcitabine (100nm (hi) to 30μm (lo)), 30mg NOSi particles, or both (NOSihi or NOSilo) and cell viability assessed. NoSi reduced cell viability by 25.99% in Panc1 and 24.38% in SMAD4-. When combined with gemcitabine, further reductions were seen in a dose dependent manner for both cell lines. We have demonstrated the in-vitro dose dependent cytotoxic effects of NOSi. When combined with GEM there is a synergistic effect resulting in improved cytotoxicity seen in both Panc1 and SMAD4- PAC cells with a differential pattern of cell death seen at high concentrations of NO. These findings suggest not only that NO is useful chemosensitizing agent but that SMAD4- may play a role in its synergism with GEM.

Smad3 Suppresses Epithelial Cell Migration and Proliferation via the Clock Gene Dec1, Which Negatively Regulates the Expression of Clock Genes Dec2 and Per1

Smad3 has circadian expression; however, whether Smad3 affects the expression of clock genes is poorly understood. Here, we investigated the regulatory mechanisms between Smad3 and the clock genes Dec1, Dec2, and Per1. In Smad3 knockout mice, the amplitude of locomotor activity was decreased, and Dec1 expression was decreased in the suprachiasmatic nucleus, liver, kidney, and tongue compared with control mice. Conversely, Dec2 and Per1 expression was increased compared with that of control mice. In Smad3 knockout mice, immunohistochemical staining revealed that Dec1 expression decreased, whereas Dec2 and Per1 expression increased in the endothelial cells of the kidney and liver. In NIH3T3 cells, Smad3 overexpression increased Dec1 expression, but decreased Dec2 and Per1 expression. In a wound-healing experiment that used Smad3 knockout mice, Dec1 expression decreased in the basal cells of squamous epithelium, promoting wound healing of the mucosa. Finally, the migration and proliferation of Smad3 knockdown squamous carcinoma cells was suppressed by Dec1 overexpression but was promoted by Dec2 overexpression. Dec1 overexpression decreased E-cadherin and proliferating cell nuclear antigen expression, whereas these expression levels were increased by Dec2 overexpression. These results suggest Smad3 is relevant to circadian rhythm and regulates cell migration and proliferation through Dec1, Dec2, and Per1 expression.

Smad4 and epithelial-mesenchymal transition proteins in colorectal carcinoma: an immunohistochemical study.

Epithelial-mesenchymal transition (EMT) plays an important role in cancer metastasis. During EMT, tumor cells acquire the capacity to migrate and invade the stroma. Activation of the transforming growth factor-b (TGF-b) signaling pathway is of major importance for the initiation of EMT. Smad4, an essential protein of this pathway, is known to complex with multiple transcription factors (e.g. Snail-1, Slug, Twist-1), in various types of cancer, promoting the repression or activation of target genes. The role of Smad4 in colorectal cancer (CRC) is not straightforward so far. In the present study forty eight resected CRC tumor specimens were immunohistochemically examined in order to assess the expression of Smad4 and its association with E-cadherin, Snail-1, Slug, Twist-1 protein expression and with various pathological parameters. Smad4 was found to be positively correlated with Snail-1, Slug and Twist-1 expression (p < 0.001). On the other hand it was negatively correlated with the expression of E-cadherin (p < 0.001). Furthermore, lymphatic invasion could be clearly associated with Smad4 expression, a finding complying with the metastatic ability of EMT cells. In conclusion, Smad4 could be considered as a central component of EMT transition in human colorectal cancer that combines with transcriptional factors to reduce E-cadherin and alter the expression of the epithelial phenotype.

The role of SMAD3 in the genetic predisposition to papillary thyroid carcinoma.

To identify and characterize the functional variants, regulatory gene networks, and potential binding targets of SMAD3 in the 15q22 thyroid cancer risk locus. We performed linkage disequilibrium (LD) and haplotype analyses to fine map the 15q22 locus. Luciferase reporter assays were applied to evaluate the regulatory effects of the candidate variants. Knockdown by small interfering RNA, microarray analysis, chromatin immunoprecipitation (ChIP) and quantitative real-time polymerase chain reaction assays were performed to reveal the regulatory gene network and identify its binding targets. We report a 25.6-kb haplotype within SMAD3 containing numerous single-nucleotide polymorphisms (SNPs) in high LD. SNPs rs17293632 and rs4562997 were identified as functional variants of SMAD3 by luciferase assays within the LD region. These variants regulate SMAD3 transcription in an allele-specific manner through enhancer elements in introns of SMAD3. Knockdown of SMAD3 in thyroid cancer cell lines revealed its regulatory gene network including two upregulated genes, SPRY4 and SPRY4-IT1. Sequence analysis and ChIP assays validated the actual binding of SMAD3 protein to multiple SMAD binding element sites in the region upstream of SPRY4. Our data provide a functional annotation of the 15q22 thyroid cancer risk locus.

Sumoylation of SMAD 4 ameliorates the oxidative stress-induced apoptosis in osteoblasts

Oxidative stress-induced mitochondrial function and cell apoptosis to osteoblasts, plays a critical role in the pathophysiology of osteoporosis. However, mechanisms underlying such process remain not yet clear. We aims in this study to investigate a possible role of SMAD (the mothers against decapentaplegic homolog 4 (SMAD4) in the oxidative stress-induced apoptosis, in homo sapiens osteoblast hFOB1.19 cells. Results demonstrated that the treatment with more than 100μM H2O2 significantly downregulated the cellular viability, whereas markedly induced apoptosis in hFOB1.19 cells. The SMAD4 was markedly reduced in both mRNA and protein levels in the H2O2 -treated hFOB1.19 cells, along with the reduction of Small ubiquitin-related modifier 1 (SUMO 1) and SUMO 2/3. The immunoprecipitation assay confirmed indicated the interaction between SUMO 1 (or SUMO 2/3) and SMAD4. Moreover, the SMAD4 overexpression markedly ameliorated the H2O2-resulted viability reduction and apoptosis induction in hFOB1.19 cells. Interestingly, such amelioration was blocked by the knockdown of SUMO 2/3. Taken together, we conclued that SMAD4 inhibits the H2O2-induced apoptosis in osteoblast hFOB1.19 cells; such inhibition might depend on the SUMOylation by SUMO 2/3. It implies a promising role of SMAD4 in oxidative stress-promoted damage to osteoblasts.

The role of ERK and Smad2 signal pathways in the alternatively activated macrophages induced by TGF-β1 and high-ambient glucose

Macrophages can be alternatively activated by TGF-β1 and high-ambient glucose, in which the role of Smad2 and the crosstalk between ERK and Smad2 pathways are not fully understood. The activation of ERK and Smad2 pathways and the expression of arginase-1 were detected by Western blot. The role of Smad2 and the relationship between ERK and Smad2 pathways were investigated by using biochemical inhibitors. The protein of arginase-1 was significantly overexpressed in RAW264.7 cells stimulated by TGF-β1 and high-ambient glucose, which can be partially blocked by not only U0126 (ERK inhibitor) but also SB431542 (Smad2 inhibitor). Furthermore, simply inhibiting one pathway had no effect on the other pathway. In conclusion, both ERK and Smad2 signal pathways are involved in the activation of macrophages induced by TGF-β1 and high-ambient glucose, while there is no crosstalk shown in the process.

MA 19.07 Does Loss of Smad7 Lead to Increased Aggressiveness of Malignant Pleural Mesothelioma?

Malignant pleural mesothelioma (MPM) is characterized by aggressive growth, limited therapeutic options and rapid recurrence following treatment. A better understanding of biological factors underlying MPM aggressiveness offers the chance to improve therapeutic strategies. Growth factors of the TGF-beta superfamily including TGF-beta itself, activins and BMPs have been repeatedly linked to MPM growth. In the current study, we focus on the role of Smad7, a key intracellular antagonist of TGF-beta and activin signaling, in MPM.

Role of Smad3 and p38 Signalling in Cigarette Smoke-induced CFTR and BK dysfunction in Primary Human Bronchial Airway Epithelial Cells

Mucociliary clearance (MCC) is a major airway host defence system that is impaired in patients with smoking-associated chronic bronchitis. This dysfunction is partially related to a decrease of airway surface liquid (ASL) volume that is in part regulated by apically expressed cystic fibrosis transmembrane conductance regulator (CFTR) and large-conductance, Ca2+-activated, and voltage dependent K+ (BK) channels. Here, data from human bronchial epithelial cells (HBEC) confirm that cigarette smoke not only downregulates CFTR activity but also inhibits BK channel function, thereby causing ASL depletion. Inhibition of signalling pathways involved in cigarette smoke-induced channel dysfunction reveals that CFTR activity is downregulated via Smad3 signalling whereas BK activity is decreased via the p38 cascade. In addition, pre-treatment with pirfenidone, a drug presently used to inhibit TGF-β signalling in idiopathic pulmonary fibrosis, ameliorated BK dysfunction and ASL volume loss. Taken together, our results highlight the importance of not only CFTR but also BK channel function in maintaining ASL homeostasis and emphasize the possibility that pirfenidone could be employed as a novel therapeutic regimen to help improve MCC in smoking-related chronic bronchitis.

SMAD4 Loss Is Associated with Cetuximab Resistance and Induction of MAPK/JNK Activation in Head and Neck Cancer Cells.

Purpose: We previously demonstrated an association between decreased SMAD4 expression and cetuximab resistance in head and neck squamous cell carcinoma (HNSCC). The purpose of this study was to further elucidate the clinical relevance of SMAD4 loss in HNSCC.Experimental Design: SMAD4 expression was assessed by IHC in 130 newly diagnosed and 43 patients with recurrent HNSCC. Correlative statistical analysis with clinicopathologic data was also performed. OncoFinder, a bioinformatics tool, was used to analyze molecular signaling in TCGA tumors with low or high SMAD4 mRNA levels. The role of SMAD4 was investigated by shRNA knockdown and gene reconstitution of HPV-negative HNSCC cell lines in vitro and in vivoResults: Our analysis revealed that SMAD4 loss was associated with an aggressive, HPV-negative, cetuximab-resistant phenotype. We found a signature of prosurvival and antiapoptotic pathways that were commonly dysregulated in SMAD4-low cases derived from TCGA-HNSCC dataset and an independent oral cavity squamous cell carcinoma (OSCC) cohort obtained from GEO. We show that SMAD4 depletion in an HNSCC cell line induces cetuximab resistance and results in worse survival in an orthotopic mouse model in vivo We implicate JNK and MAPK activation as mediators of cetuximab resistance and provide the foundation for the concomitant EGFR and JNK/MAPK inhibition as a potential strategy for overcoming cetuximab resistance in HNSCCs with SMAD4 loss.Conclusions: Our study demonstrates that loss of SMAD4 expression is a signature characterizing the cetuximab-resistant phenotype and suggests that SMAD4 expression may be a determinant of sensitivity/resistance to EGFR/MAPK or EGFR/JNK inhibition in HPV-negative HNSCC tumors. Clin Cancer Res; 23(17); 5162-75. ©2017 AACR.

Abstract 98: Canonical TGF-β1 Signaling in Cardiomyocytes is Essential to Maintain Basal Cardiac Function

The role of canonical transforming growth factor-β (TGF-β) pathway is well recognized in fibroblast biology and fibrosis in diseased hearts. However, its role in cardiomyocyte (CM) biology is not clear. SMAD4 is the central intracellular mediator of canonical TGF-β signaling. Herein, we investigate the role of SMAD4 in CM-biology and cardiac pathophysiology. SMAD4 homozygous floxed ( SMAD4 fl/fl ) and heterozygous floxed ( SMAD4 fl/- ) mice were crossed with α-myosin heavy chain (Mer-Cre-Mer) to create conditional CM-specific SMAD4-KO ( SMAD4 fl/fl Cre +/- ) and SMAD4 haploinsufficiency ( SMAD4 fl/- Cre +/- ), respectively. At 10 Wks of age, mice were subjected to well established tamoxifen diet protocol for 2 Wks. Echocardiographic analysis at 4 Wks post-tamoxifen treatment reveals that CM-specific loss of SMAD4 leads to dilatative ventricular remodeling as reflected by significantly increased LVIDs. This dilatative remodeling was associated with severe ventricular dysfunction as reflected by significantly reduced ejection fraction (EF) and fractional shortening (FS). Both HW/BW and LW/BW were significantly elevated in SMAD4 KO mice, suggesting pathological hypertrophy and heart failure in KOs. Analysis of Masson trichrome stained heart sections reveals a marked increase in fibrosis in the KO hearts. Q-PCR analysis showed the re-expression of fetal gene program (ANP, BNP), further confirming pathological remodeling in the KO hearts. As the heart functions of heterozygous mice and littermate controls were comparable at baseline, we stress them with TAC surgery. Consistent with KO findings, at 4 Wks post-TAC, heterozygous mice demonstrated characteristic heart failure phenotype. Taken together, these findings suggest that SMAD4 is required to maintain basal cardiac function and to prevent adverse ventricular remodeling in a pressure-overloaded heart.

Abstract 1958: Opposing roles of Smad2 and Smad3 in the regulation of growth and invasion of TNBC through TMEPAI

Abstract The dependency of triple negative breast cancers (TNBC) on TGF-β signaling activity for their growth and metastasis is well documented. Breast tumors develop resistance to TGF-β-induced growth inhibition, which helps in tumor progression. Additionally, TGF-β is enriched in the tumor microenvironment and is a key inducer of epithelial to mesenchymal transition (EMT) in breast cancer. In an effort to understand the mechanisms by which TGF-β induces breast tumorigenesis, we sought to identify the relative individual contributions of Smad2 and Smad3 in mediating cancer cell growth and metastasis by TGF-β. Screening of several TNBC cell lines showed increased Smad3/Smad2 expression ratio compared to normal mammary epithelial cells, which suggested breast cancer cells may escape TGF-β mediated cell cycle arrest by altering their relative expressions of Smad3 and Smad2. Since overexpression of R-Smads may not always accurately reflect the functional status of the endogenous molecules, we individually knocked down each R-Smad and tested its effect on pro-oncogenic behavior of TGF-β. Although Smad2 deficiency has no effect on breast cancer cell behavior, Smad3 deficiency reduced growth and invasion capacity of breast cancer cells. Interestingly, while Smad3 deficiency was associated with reduced TMEPAI/PMEPA1 and EMT gene expressions and increased expression of cell cycle inhibitors, Smad2 deficiency had opposite effect on these regulators. Moreover, the decreased growth, invasion and associated gene expressions were largely reversed by overexpressing TMEPAI in Smad3 knockdown cells, suggesting that Smad3-TMEPAI axis may be involved in subverting growth suppressive effects of TGF-β into growth promotion. Compared to control and Smad2 deficient cells, Smad3 deficient cells had markedly elevated PTEN protein levels and suppressed Akt phosphorylation both under basal conditions and TGF-β stimulation. We identified that Smad3 but not Smad2 plays an important role in stimulating TMEPAI expression, growth and EMT in triple negative breast cancer cells by promoting TGF-β dependent non-canonical signaling by decreasing the cellular content of PTEN and p27 in a TMEPAI dependent manner. Taken together, the results demonstrate a novel role for Smad3 in cancer transformation and cancer progression through TMEPAI. Current therapeutic strategies are aiming at antagonizing the whole TGF-β signaling thereby completely blocking both Smad2 and Smad3 signaling pathways. Selective targeting of TGF-β-Smad3-TMEPAI axis may be more beneficial in triple negative breast cancer therapy and prevention. Citation Format: Prajjal K. Singha, Srilakshmi Pandeswara, Manjeri A. Venkatachalam, Pothana Saikumar. Opposing roles of Smad2 and Smad3 in the regulation of growth and invasion of TNBC through TMEPAI [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1958. doi:10.1158/1538-7445.AM2017-1958

Abstract 2255: SMAD4 loss is associated with poor prognosis in Middle Eastern colorectal cancer

Abstract Background: Colorectal cancer (CRC) is major cause of morbidity and mortality in cancer patients worldwide and it ranks as the most common cancer in males and the third most common among females in Saudi Arabia. Alteration in TGF-β pathway has been reported in many cancers. So In search for new molecular targets we analyzed the role of SMAD4, critical TGF-β pathway mediator, in Saudi colorectal cancers Methods: 426 CRC cases were analyzed for SMAD4 mutations by targeted capture sequencing and protein expression status by immunohistochemistry in a tissue microarray format. Results were analyzed for association with any clinico-pathological parameters and for prognostic significance. Results: SMAD4 mutations were detected in 11.9 %( 50/418) cases of Saudi colorectal cancers. CRC with SMAD4 mutations were significantly associated with NRAS mutations (p=0.0481). SMAD4 complete loss of expression by immunohistochemistry was seen in 12.8% (52/404) cases and this loss was associated with young age (p=0.0236) and inversely with MSI-high tumors (p=0.0005). SMAD4 expression loss by immunohistochemistry and mutation were significantly associated with each other (p=0.0028). In the multivariate analysis using the Cox proportional hazard model SMAD4 expression loss was an independent marker of poor prognosis (p=0.0119) Conclusion: SMAD4 alteration was found to be associated with a poor overall survival in the Saudi colorectal cancer patients. With the advent of targeted anticancer therapy, this study confirms the findings of other investigators and highlights a potential target which can be exploited to improve the survival of CRC patients in the Kingdom of Saudi Arabia Citation Format: Maqbool Ahmed, Abdul K. Siraj, Tariq Masoodi, Rong Bu, Fouad Al-Dayel, Khawla S. Al-Kuraya. SMAD4 loss is associated with poor prognosis in Middle Eastern colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2255. doi:10.1158/1538-7445.AM2017-2255

The role of Smad7 in pancreatic fibroblasts in modulating cerulein-induced pancreatic fibrosis

The role of Smad7 in pancreatic fibroblasts in modulating cerulein-induced pancreatic fibrosis

Smad4 expression and chemosensitivity in non-small cell lung cancer.

e20550 Background: Smad4 is a tumor suppressor that transduces transforming growth factor beta signaling and regulates genomic stability. We previously found that reduced Smad4 expression was associated with increased DNA damage in both human NSCLC and murine NSCLC models and that reduced Smad4 expression inhibits DNA repair and increases sensitivity to DNA topoisomerase inhibitors. In this study, we assessed the association between reduced Smad4 expression and DNA topoisomerase inhibitor sensitivity in human NSCLC as well as the relationship between Smad4 mutation and homozygous deletion and molecular alterations in other DNA repair molecules. Methods: After IRB approval, we retrospectively identified NSCLC patients who received etoposide or gemcitabine and had an evaluable tumor on CT scan at the University of Colorado Hospital between 2004 to 2014. Chemotherapeutic response was quantified by RECIST criteria, while Smad4 expression was assessed by immunohistochemistry (IHC) and quantified on a 0-300 scale. The relationship between Smad4 mutation and other DNA repair molecule alterations was assessed using TCGA data via cBioPortal. Results: Of the 21 evaluable patients, 19/21 received gemcitabine or etoposide for advanced (stage 3 or 4) disease and 10/21 received these agents with concurrent radiation therapy. Reduced Smad4 expression (IHC score &lt; 100) occurred in 8/21 patients and was associated with non-significant trend (p = 0.18, fisher exact test) toward responsiveness to gemcitabine or etoposide. TCGA data analysis revealed that while Smad4 mutation or homozygous loss was not associated with reduced survival, Smad4 alterations were mutually exclusive to defects in DNA repair molecules. Conclusions: Reduced Smad4 expression may be a biomarker for responsiveness to treatment with chemotherapeutic drugs that inhibit DNA topoisomerase, though this study was underpowered to detect this. That Smad4 signaling alterations are mutually exclusive with alterations in other DNA repair machinery is consistent with a role of Smad4 in regulating DNA repair.

Smad4 Inhibits VEGF-A and VEGF-C Expressions via Enhancing Smad3 Phosphorylation in Colon Cancer.

Smad4 is a critical factor in the TGF-β pathway and is involved in tumor progression and metastasis, but the role of Smad4 in colon cancer cells is unclear. The aim of this study is to explore the effect and the underlying mechanism of Smad4 on the growth, migration and apoptosis of colon cancer cells as well as vascular endothelial growth factor (VEGF)-A and VEGF-C secreted by these cells. In this study, we showed that Smad4, VEGF-A, and VEGF-C are independent prognostic factors of colon cancer, and Smad4 expression was negatively correlated with VEGF-A and -C in samples. We found that Smad4 mRNA and protein levels in colon cancer cells, particularly in HCT-116 cells, were significantly lower than those in the human intestinal epithelial cell line (HIEC). Smad4 overexpression promoted tumor cell apoptosis, inhibited VEGF-A and -C expression in vitro and in vivo, but had no effect on cell proliferation and migration. Tail vein injection of the virus inhibited xenograft growth in nude mice. Importantly, we also demonstrated that Smad4 could increase the phosphorylation level of Smad3, but not Smad2, which may be one of the mechanisms underlying these effects of Smad4 in colon cancer. Therefore, Smad4 may be a new target for the treatment of colon cancer. Anat Rec, 300:1560-1569, 2017. © 2017 Wiley Periodicals, Inc.