Project description:Inappropriate activation of developmental pathways is a well-recognized tumor-promoting mechanism. Here we show that overexpression of the homeoprotein Six1, normally a developmentally restricted transcriptional regulator, increases Transforming Growth Factor-beta (TGF-beta) signaling in mammary carcinoma cells and induces an epithelial to mesenchymal transition (EMT) that is in part dependent on its ability to increase TGF-beta signaling. TGF-beta signaling and EMT have been implicated in metastatic dissemination of carcinoma. Using spontaneous and experimental metastasis mouse models, we demonstrate that Six1 overexpression promotes breast cancer metastasis. In addition, we show that, like its induction of EMT, Six1-induced experimental metastasis is dependent on its ability to activate TGF-beta signaling. Importantly, in human breast cancers Six1 significantly correlates with nuclear Smad3, and thus increased TGF-beta signaling. Further, breast cancer patients whose tumors overexpress Six1 have a shortened time to relapse and metastasis, and an overall decrease in survival. Finally, we show that the effects of Six1 on tumor progression likely extend beyond breast cancer, since its overexpression correlates with adverse outcomes in numerous other cancers, including brain, cervical, prostate, colon, kidney, and liver, amongst others. Our findings argue that Six1, acting through TGF-beta signaling and EMT, is a powerful and global promoter of cancer metastasis.
Project description:BRMS1L (breast cancer metastasis suppressor 1 like,BRMS1-like) is a component of the SIN3A-HDAC corepressor complex that suppresses target gene transcription. Here, we show that reduced BRMS1L in breast cancer tissues is associated with tumor metastasis and poor patient survival. Functionally, BRMS1L inhibits migration and invasion of breast cancer cells by inhibiting epithelial-mesenchymal transition (EMT). These effects are mediated by epigenetic silencing of FZD10, a receptor for Wnt signaling, by facilitating the recruitment of HDAC1 to its promoter and enhancing histone H3K9 deacetylation. Consequently, BRMS1L-induced FZD10 silencing inhibits aberrant activation of WNT3-FZD10--catenin signaling. Furthermore, BRMS1L is a target of miR-106b and miR-106b upregulation leads to BRMS1L reduction in breast cancer cells. RNAi-mediated silencing of BRMS1L expression promotes metastasis of breast cancer xenografts in immunocompromised mice, while ectopic BRMS1L expression inhibits metastasis. Therefore, BRMS1L provides an epigenetic regulation of Wnt signaling in breast cancer cells and acts as a breast cancer metastasis suppressor. Ther transfection analysis used here were further desxribed in Chang Gong, eta al.2013. miR-106b expression determines the proliferation paradox of TGF-β in breast cancer cells. Oncogene. 2013
Project description:Epithelial-to-mesenchymal transition (EMT) plays a crucial role in metastasis, which is the leading cause of death in breast cancer patients. We show that Cdc42 GTPase-activating protein (CdGAP) promotes tumor formation and metastasis to lungs in the HER2-positive (HER2+) murine breast cancer model. CdGAP facilitates intravasation, extravasation, and growth at metastatic sites. CdGAP depletion in HER2+ murine primary tumors mediates crosstalk with a Dlc1-RhoA pathway and is associated with a transforming growth factor-β (TGF-β)-induced EMT transcriptional signature. To further delineate the molecular mechanisms underlying the pro-migratory role of CdGAP in breast cancer cells, we searched for CdGAP interactors by performing a proteomic analysis using HEK293 cells overexpressing GFP-CdGAP. We found that CdGAP interacts with the adaptor Talin to modulate focal adhesion dynamics and integrin activation. Moreover, HER2+ breast cancer patients with high CdGAP mRNA expression combined with a high TGF-β-EMT signature are more likely to present lymph node invasion. Our results suggest CdGAP as a candidate therapeutic target for HER2+ metastatic breast cancer by inhibiting TGF-β and Integrin/Talin signaling pathways.
Project description:BRMS1L (breast cancer metastasis suppressor 1 likeM-oM-<M-^LBRMS1-like) is a component of the SIN3A-HDAC corepressor complex that suppresses target gene transcription. Here, we show that reduced BRMS1L in breast cancer tissues is associated with tumor metastasis and poor patient survival. Functionally, BRMS1L inhibits migration and invasion of breast cancer cells by inhibiting epithelial-mesenchymal transition (EMT). These effects are mediated by epigenetic silencing of FZD10, a receptor for Wnt signaling, by facilitating the recruitment of HDAC1 to its promoter and enhancing histone H3K9 deacetylation. Consequently, BRMS1L-induced FZD10 silencing inhibits aberrant activation of WNT3-FZD10-M-oM-^AM-"-catenin signaling. Furthermore, BRMS1L is a target of miR-106b and miR-106b upregulation leads to BRMS1L reduction in breast cancer cells. RNAi-mediated silencing of BRMS1L expression promotes metastasis of breast cancer xenografts in immunocompromised mice, while ectopic BRMS1L expression inhibits metastasis. Therefore, BRMS1L provides an epigenetic regulation of Wnt signaling in breast cancer cells and acts as a breast cancer metastasis suppressor. Ther transfection analysis used here were further desxribed in Chang Gong, eta al.2013. miR-106b expression determines the proliferation paradox of TGF-M-NM-2 in breast cancer cells. Oncogene. 2013 A two chip study using total RNA recovered from MDA-MB-231 breast cancer cells transfected with negative control vector or vector overexpressing BRMS1L for 24 hours. Each chip measures the expression 45033 genes were collected from the authoritative data source including NCBI.
Project description:Protein deacetylase SIRT7 is significantly downregulated in lung metastases of human patient and mouse tissues, and predicted metastasis-free survival. To explore the roles of SIRT7 in breast cancer, we analysed the gene expressions in breast cancer BT549 cells with SIRT7 knockdown or not.
Project description:TGF-beta is one of the key cytokines implicated in various disease processes including cancer. TGF-beta inhibits growth and promotes apoptosis in normal epithelial cells and in contrast, acts as a pro-tumour cytokine by promoting tumour angiogenesis, immune-escape and metastasis. The effect of TGF-beta on the regulation of gene expression is cell-type specific. In order to identify TGF-beta regulated genes in different cell-types, we followed the expression profiling approach. Keywords: cell type specific response to TGF-beta
Project description:Analysis of transcriptome post hypoxia and TGF-β treatment in breast cancer In order to explore the role of TGF-β signaling in mediating the alternative splicing program in breast cancer, we profiled the pre-mRNA splicing and mRNA gene expression upon hypoxia and TGF-β treatment using Human Transcriptome Array 2.0.
Project description:Purpose: Tumor metastasis is the main cause of death from breast cancer patients and cell migration plays a critical role in metastasis. Recent studies have shown long non-coding RNAs (lncRNAs) play an essential role in the initiation and progression of cancer. In the present study, the role of a LncRNA, Rho GTPase Activating Protein 5- Antisense 1 (ARHGAP5-AS1) in breast cancer was investigated. Methods: RNA sequencing was performed to find out dysregulated LncRNAs in MDA-MB-231-LM2 cells. Transwell migration assays and F-actin staining were utilized to estimate cell migration ability. RNA pulldown assays and RNA immunoprecipitation were used to prove the interaction between ARHGAP5-AS1 and SMAD7. Western blot and immunofluorescence imaging were used to examine the protein levels. Dual luciferase reporter assays were performed to evaluate the activation of TGF-β signaling. Results: Compared to MDA-MB-231 cells, the expression of LncRNA ARHGAP5-AS1 (NR_027263) was significantly suppressed in its highly metastatic subtype MDA-MB-231-LM2 cells. Functional study showed ARHGAP5-AS1 could inhibit cell migration via suppression of stress fibers in breast cancer cell lines. Afterwards, SMAD7 was further identified to interact with ARHGAP5-AS1 by its PY motif and thus its ubiquitination and degradation was blocked due to reduced interaction with E3 ligase SMURF1 and SMURF2. Moreover, ARHGAP5-AS1 could inhibit TGF-β signaling pathway due to its inhibitory role on SMAD7. Conclusion: Overall, these findings demonstrate that ARHGAP5-AS1 inhibits breast cancer cell migration and could serve as a novel biomarker for breast cancer metastasis and a potent target for the treatment in the future.
Project description:The activation of RIG-I-like receptor (RLR) signaling in cancer cells is widely recognized as a critical cancer therapy method. The expected mechanism of RLR ligand-mediated cancer therapy involves the promotion of cancer cell death and strong induction of interferon (IFN)-β that affects the tumor microenvironment. We have recently shown that activation of RLR signaling in triple-negative breast cancer cells (TNBC) attenuates TGF-β signaling, which partly contributes to the promotion of cancer cell pyroptosis. However, the consequences of suppression of TGF-β signaling by RLR ligands with respect to IFN-β-mediated tumor suppression are not well characterized. This study showed that cytosolic induction of a typical RLR ligand polyI:C in cancer cells produces significant levels of IFN-β, which inhibits the growth of the surrounding cancer cells. In addition, IFN-β-induced cell cycle arrest in surrounding cancer cells was inhibited by the expression of constitutively active Smad3 (caSmad3). caSmad3 suppresses IFN-β expression through the alleviation of IRF3 binding to the canonical target genes, as suggested by ChIP-seq analysis. Based on these findings, a new facet of the pro-tumorigenic function of TGF-β that suppresses IFN-β expression is suggested when exploiting RLR-mediated cancer treatment in TNBC.