Project description:Deregulation of the transforming growth factor-? (TGF?) signaling pathway in epithelial ovarian cancer has been reported, but the precise mechanism underlying disrupted TGF? signaling in the disease remains unclear. We performed chromatin immunoprecipitation followed by sequencing (ChIP-seq) to investigate genome-wide screening of TGF?-induced SMAD4 binding in epithelial ovarian cancer. Following TGF? stimulation of the A2780 epithelial ovarian cancer cell line, we identified 2,362 SMAD4 binding loci and 318 differentially expressed SMAD4 target genes. Comprehensive examination of SMAD4-bound loci, revealed four distinct binding patterns: 1) Basal; 2) Shift; 3) Stimulated Only; 4) Unstimulated Only. SMAD4-bound loci were primarily classified as either Stimulated only (74%) or Shift (25%), indicating that TGF?-stimulation alters SMAD4 binding patterns in epithelial ovarian cancer cells compared to normal epithelial cells. Furthermore, based on gene regulatory network analysis, we determined that the TGF?-induced SMAD4-dependent regulatory network was strikingly different in ovarian cancer compared to normal cells. Importantly, the TGF?/SMAD4 target genes identified in the A2780 epithelial ovarian cancer cell line were predictive of patient survival, based on in silico mining of publically available patient data bases. In conclusion, our data highlight the utility of next generation sequencing technology to identify genome-wide SMAD4 target genes in epithelial ovarian cancer. The results link aberrant TGF?/SMAD signaling to ovarian tumorigenesis. Furthermore, the identified SMAD4 binding loci, combined with gene expression profiling and in silico data mining of patient cohorts, may provide a powerful approach to determine potential gene signatures with biological and future translational research in ovarian and other cancers. ChIP-Seq: 1 control lane. 4 unstimulated lanes 4 stimulated lanes Gene expression: 3 technical replicates each of SMAD4 stimulated and SMAD4 unstimulated cells
Project description:Lung cancer remains the leading cause of cancer death. Genome sequencing of lung tumors from patients with Squamous Cell Carcinoma has identified SMAD4 to be frequently mutated. Here we used a novel mouse model to determine the molecular mechanisms regulated by loss of Smad4 which lead to lung cancer progression. Mice with ablation of Pten and Smad4 in airway epithelium developed metastatic adenosquamous tumors. Comparative transcriptomic and in vivo cistromic analyses determined that loss of PTEN and SMAD4 resulted in activation of the ELF3 and the ErbB2 pathway due to decreased ERRFI1M-bM-^@M-^Ys expression, a negative regulator of ERBB2 in mice and human cells. The combinatorial inhibition of ErbB2 and Akt signaling attenuated tumor progression and cell invasion, respectively. Expression profiles analysis of human lung tumors substantiated the importance of the ErbB2/Akt/ELF3 signaling pathway as both prognostic biomarkers and therapeutic drug targets for treating lung cancer. Examination of genome-wide SMAD4 binding in 7-month-old Ptend/d mouse lung.
Project description:The transforming growth factor ? (TGF-?) signaling protein SMAD4 is lost in 60% of PDAC, and this has been associated with poorer prognosis. We expressed SMAD4 in human PDAC cell lines BxPC3, by selection of stable clones containing an inducible SMAD4 Tet-ON construct. After 24h of SMAD4 expression, TGF-? signaling-dependent G1-arrest was observed in BxPC3 cells with an increase in the G1-phase fraction from 48.9% to 71.5%. Microarray analysis of gene expression at 8h, 24h, and 48h after SMAD4 expression characterized the regulatory impact of SMAD4 expression in a SMAD4-null PDAC cell line and identified novel targets of TGF-? signaling. We used BxPC3 cells infected by pINDCUER-SMAD4-Puro virus. After 24h, 1µg/ml doxycycline was added to experimental wells. We profiled the gene expression after 8hr, 24hr and 48hr treatment with doxycycline as well as control at 8hr.
Project description:Background: Patients with small intestinal neuroendocrine tumors (SINETs) frequently present with lymph node and liver metastases at the time of diagnosis, but the molecular changes that lead to the progression of these tumors are largely unknown. Sequencing studies have only identified recurrent point mutations in a single gene, CDKN1B, with heterozygous mutations in less than 10% of all tumors. Although SINETs are genetically stable tumors with a low frequency of point mutations and indels, they often harbor recurrent hemizygous copy number alterations (CNAs) yet the functional implications of these CNA are unclear. Methods: Utilizing comparative genomic hybridization (CGH) arrays we analyzed the CNA profile of 131 SINETs from 117 patients. Two tumor suppressor genes and corresponding proteins i.e. SMAD4, and CDKN1B, were further characterized using a tissue microarray (TMA) with 846 SINETs. Immunohistochemistry (IHC) was used to quantify protein expression in TMA samples and this was correlated with chromosome number evaluated with fluorescent in-situ hybridization (FISH). Intestinal tissue from a Smad4+/- mouse model was used to detect entero-endocrine cell hyperplasia with IHC. Results: Analyzing the CGH arrays we found loss of chromosome 18q and SMAD4 in 71% of SINETs and that focal loss of chromosome 12 affecting the CDKN1B was present in 9.4% of SINETs. No homozygous loss of chromosome 18 was detected. Hemizygous loss of SMAD4, but not CDKN1B, significantly correlated with reduced protein levels but hemizygous loss of SMAD4 did not induce entero-endocrine cell hyperplasia in the Smad4+/- mouse model. Conclusions: Hemizygous loss of chromosome 18q and the SMAD4 gene is the most common genetic event in SINETs and our results suggests that this could influence SMAD4 protein expression. Although SMAD4 haploinsufficiency alone did not induce tumor initiation, loss of chromosome 18 could represent an evolutionary advantage in SINETs explaining the high prevalence of this aberration. Functional consequences of reduced SMAD4 protein levels could hypothetically be a potential mechanism as to why loss of chromosome 18 appears to be clonally selected in SINETs.
Project description:We evaluated the role of TTF-1/NKX2-1 on Smad3 and Smad4 binding in lung cancer cell lines. Smad3 binding sites in A549 cells and Smad3, Smad4, and TTF-1/NKX2-1 binding sites in H441 cells were determined by ChIP-seq.
Project description:TGF-beta/Smads signaling plays important roles in vascular integrity. To identify potential Smad4 target genes in brain endothelial cells that control cerebrovascular integrity, the microarray assay was performed to compare the gene expression profiles of bEnd3 transfected with Smad4-siRNA and control-siRNA. bEnd3 cells were infected by Smad4-siRNA or control-siRNA retrovirus particles produced by PLAT-E packaging cells and selected by puromycin. The specific and control RNAi cells were used for RNA extraction and hybridization on Affymetrix microarrays. Two independent infections were performed and samples were pooled in order to obtain representative populations.
Project description:Mutations of SMAD family member 4 (Smad4) gene caused Hereditary Hemorrhagic Telangiectasia (HHT). It was believed that bleeding disorders were caused by arteriovenous malformation in this syndrome. Although several studies indicated dysfunction of platelets from HHT patient, the role(s) of smad4 in platelet function has not been examined. In this study, using megakaryocyte/platelet-specific Smad4-deficient mice, we investigated the physiological function of Smad4 in platelet activation and the underlying mechanism. Microarray data demonstrated that the level of mRNA for multiple genes changed in Smad4 deficient platelet. For microarray analysis, total mRNA was extracted from washed platelets from Smad4f/f or Smad4M-bM-^HM-^R/M-bM-^HM-^R mice (for each group, n=6). mRNA was labeled and hybridized to Affymetrix Mouse Genome 430 2.0 chips according to manufacturer's instructions (Affymetrix).
Project description:In differentiated mouse ESCs, most of the nodal/activin responsive genes are dependent on both Smad4 and Trim33, some are solely dependent on Smad4, and some are dependent on Trim33. Ebs at Day2.5 from WT, Smad4 null, and Trim33 knock-down ESCs, were treated with activin or SB 431542 for 2 h.